2013-09-05
2013년 이동 및 무선통신 단기강좌 3GPP LTE(-A): Part II MAC & Network
2013. 8. 22. Jae-Hyun Kim [email protected]
Wireless Internet aNd Network Engineering Research Lab. http://winner.ajou.ac.kr School of Electrical and Computer Engineering Ajou University, Korea
Contents
Introduction
Network Architecture
User Plane Protocol
Control Plane Protocol
LTE-Advanced Features
Release 12 Issues
Summary
2
1 2013-09-05
Introduction
3
Release of 3GPP specifications
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
GSM/GPRS/EDGE enhancements
Release 99 - W-CDMA
Release 4 – TDD
Release 5 – HSDPA, IMS
Release 6 – HSUPA, MBMS, IMS+
Release 7 – HSPA+(MIMO, HOM etc.)
Release 8 – LTE, SAE ITU-R M.1457 IMT-2000 Recommendations Release 9 Small LTE/SAE enhancement
Release 10 LTE-Advanced
Release 11 – Interconnection
Release 12
WCDMA WCDMA LTE LTE 최초 상용화 국내 상용화 최초 상용화 국내 상용화 4
2 2013-09-05
3GPP Standards
Version Released Information
Release 98 1998 This and earlier releases specify pre-3G GSM networks
Release 99 2000 Q1 Specified the first UMTS 3G networks, incorporating a CDMA air interface
Release 4 2001 Q2 added features including an all-IP Core Network
Release 5 2002 Q1 Introduced IMS and HSDPA Integrated operation with Wireless LAN networks and adds HSUPA, MBMS, enhancements to IMS such Release 6 2004 Q4 as Push to Talk over Cellular (PoC),GAN (Generic Access Network) Focuses on decreasing latency, improvements to QoS and real-time applications such as VoIP. This speci fication also focus on HSPA+(High Speed Packet Access Evolution), SIM high-speed protocol and contact Release 7 2007 Q4 less front-end interface (Near Field Communication enabling operators to deliver contactless services lik e Mobile Payments), EDGE Evolution. Frozen LTE, All-IP Network (SAE). Release 8 constitutes a refactoring of UMTS as an entirely IP based fourth-g Release 8 Dec. 2008 eneration network. Frozen Release 9 SAES Enhancements, WiMaX and LTE/UMTS Interoperability Dec. 2009 Frozen LTE Advanced fulfilling IMT Advanced 4G requirements. Backwards compatible with release 8 (LTE). Release 10 Mar. 2011 Multi-Cell HSDPA (4 carriers). Frozen Sep. 2012 / Advanced IP Interconnection of Services. Service layer interconnection between national operators/ Release 11 Some works are carriers as well as third party application providers still in progress Stage 1 frozen Release 12 Mar. 2013 / (Content still open (as of October 2012).) In progress
5
Network Architecture
6
3 2013-09-05
Evolution of Network Architecture
7
Evolution Path of Core Network
E-UTRAN(Evolved Universal Terrestrial Radio Access Network)
S1
X2
• NB : NodeB • eNB : E-UTRAN NodeB • RNC : Radio Network Controller • aGW : Access Gateway • SGSN : Serving GPRS Support Node • MME : Mobility Management Entity • GGSN : Gateway GPRS Support Node • UPE : User Plane Entity 8
4 2013-09-05
UMTS Architecture(Release-5)
3G Core Network (CN) External Network Radio Access Network (RAN) (UTRAN) R-SGW SS7 CSCF
HSS Cx Mg RNC CSCF MGCF T-SGW HLR Mr MRF Node B Iur Gr Mc SS7 Gi Iub Iu Gn Gi PCM RNC SGSN GGSN MGW PSTN
Gi(IP) Internet RNC : Radio Network Controller SS7 : Signal System No.7 SGSN : Serving GPRS Support Node R-SGW : Roaming Signaling Gateway GGSN : Gateway GPRS Support Node T-SGW : Transport Signaling Gateway CSCF : Call State Control Function MGCF : Media Gateway Control Function MRF : Multimedia Resource Function 9
Overall Architectural Overview
EPS (Evolved Packet System) network elements
Interface for data plane Interface for control plane
E-UTRAN Evolved Packet Core (EPC)
E-SMLC: Evolved Serving Mobile Location Centre HSS: Home Subscriber Server GMLC: Gateway Mobile Location Centre PCRF: Policy Control and Charging Rules Function
10 . 3GPP TS 36.300 V11.6.0 “E-UTRA and E-UTRAN; Overall description”, June, 2013
5 2013-09-05
Core Network Elements
Network Elements Features
. Policy control decision making PCRF . Controlling the flow-based charging functionalities in the PCEF (Policy Control (Policy Control and Enforcement Function) which resides in the P-GW Charging Rules Function) • QoS authorization (QoS class identifier and bit rates)
. Contains users’ SAE subscription data such as EPS-subscribed QoS profile HSS and any access restrictions for roaming (Home Subscriber Server) . Information about the PDNs to which the user can connect . Identity of the MME to which the user is currently attached or registered
. Manage the overall coordination and scheduling of resources required to find E-SMLC the location of a UE attached to E-UTRAN (Evolved Serving Mobile . Calculate the final location of UE based on the estimates it receives Location Centre) . Estimate the UE speed and the achieved accuracy
. Contain functionalities required to support location services GMLC . Send positioning requests to the MME and receives the final location estimates (Gateway Mobile Location Centre)
11
Core Network Elements
Network Elements Features . IP address allocation for the UE P-GW (PDN Gateway) . QoS enforcement and flow-based charging according to the PCRF
. All user IP packets are transferred through the S-GW . LMA (Local Mobility Anchor) when the UE moves between eNode-Bs . Retains the information about the bearers when the UE is in idle state . Temporarily buffers downlink data while the MME initiates paging of the UE to S-GW (Serving re-establish the bearers Gateway) . Collecting information for charging (the volume of data sent/rcvd) . Mobility anchor for inter-working with GPRS and UMTS
. Process the signaling between the UE and the CN (Core Network) (NAS: Non- Access Stratum) . Bearer & Connection management MME • Establishment, maintenance and release of the bearers (Mobility Management Entity) • Establishment of the connection and security between the network and UE
12
6 2013-09-05
Access Network
Overall architecture E-UTRAN consists of eNBs eNBs are interconnected with each other by X2 interface eNBs are connected by means of S1 interface to the EPC S1 interface supports a many-to-many relation between MMEs/S-GW and eNBs
1
S
S
S
1 1
S
1 S 5 S
1 1 S
S X 1 2 2 1 X S
13 . 3GPP TS 36.300 V11.6.0 “E-UTRA and E-UTRAN; Overall description”, June, 2013
Access Network
The eNB hosts following functions RRM (Radio Resource Management) Radio Bearer Control Radio Admission Control Connection Mobility Control Dynamic allocation of resources to UEs (scheduling)
Processing user plane data IP header compression and encryption of user data stream AS security Selection of an MME at UE attachment when no routing to an MME can be determined from the information provided by the UE Forwarding of user plane data towards S-GW
Measurement and measurement reporting configuration for mobility and scheduling
Scheduling and transmission of control messages from the MME paging messages broadcast information PWS (Public Warning System) messages
CSG (Closed Subscriber Group) handling
Transport level packet marking in the uplink (ex. Setting the DSCP (DiffServ Code Point)
14 . 3GPP TS 36.300 V11.6.0 “E-UTRA and E-UTRAN; Overall description”, June, 2013
7 2013-09-05
Interfaces
X2 and S1 user plane aspect IP packet for a UE is encapsulated and tunneled using GTP-U (GPRS Tunneling Protocol – User Plane) Local transport protocol is UDP • No flow control, No error control X2 and S1 control plane aspect S1AP (S1 Application Protocol) is used to transport the signaling message between eNode-B and the MME Local transport protocol is SCTP • Guarantees delivery of signaling messages • Support multiple SAE bearers
S1-AP S1-AP
SCTP SCTP
IP IP
L2 L2
L1 Access Layer
S1-MME HeNB MME User plane for S1-U interface Control plane for S1-MME Interface . SCTP : Stream Control Transmission Protocol 15 . 3GPP TS 36.300 V11.6.0 “E-UTRA and E-UTRAN; Overall description”, June, 2013
EPS Bearer Service Architecture
EPS bearer / E-RAB is established when the UE connects to a PDN Default bearer remains established throughout the lifetime of the PDN connection Dedicated bearer Any additional EPS bearer/E-RAB that is established to the same PDN is referred to as a dedicated bearer.
E-UTRAN EPC Internet
UE eNB S-GW P-GW Peer Entity
End-to-end Service
EPS Bearer External Bearer
E-RAB S5/S8 Bearer
Radio Bearer S1 Bearer
RadioS1 S5/S8 Gi 16 . 3GPP TS 36.300 V11.6.0 “E-UTRA and E-UTRAN; Overall description”, June, 2013
8 2013-09-05
QoS and EPS Bearers
Multiple applications have different QoS requirements Different bearers are set up within EPS each being associated with a QoS GBR bearers Permanent allocation of dedicated transmission resources ex) VoIP Non-GBR bearers Do not guarantee any particular bit rate ex) web browsing, FTP transfer Each bearer has an associated QCI, and an ARP Priority and packet delay budget RLC mode, scheduling policy, queue management and rate shaping policy
17 GBR : Minimum Guaranteed Bit Rate QCI: QoS Class Identifier ARP: Allocation and Retention Priority
Standardized QCI for LTE
QCI Reso Packet Packet Prior (QoS Class urce Delay Error Loss Example Services ity Identifier) Type Budget Rate
1 2 100ms 10-2 Conversational Voice
2 4 150ms 10-3 Conversational Video (Live Streaming) GBR 3 3 50ms 10-3 Real Time Gaming
4 5 300ms 10-6 Non-Conversational Video (Buffered Streaming) 5 1 100ms 10-6 IMS Signaling Video (Buffered Streaming), 6 6 300ms 10-6 TCP-based (e.g., www, e-mail, chat, ftp, p2p file sharing, progressive video, etc.)
Non- 7 GBR 7 100ms 10-3 Voice, Video (Live Streaming)Interactive Gaming
8 8 Video (Buffered Streaming), 300ms 10-6 TCP-based (e.g., www, e-mail, chat, ftp, p2p file sharing, 9 9 progressive video, etc.) 18 . 3GPP TS 23.203 v12.1.0, “Policy and charging control architecture,” Jun. 2013.
9 2013-09-05
User Plane Protocol Packet Data Convergence Protocol Radio Link Control Medium Access Control
19
Overview
PDCP layer Process RRC messages in the control plane and IP messages in the user plane Header compression Security reordering and retransmission during handover
RLC layer Segmentation and reassembly ARQ Reordering for HARQ
MAC layer Multiplexing of data from different radio bearer Achieve QoS for each radio bearer Report the eNodeB to the buffer size for uplink PDCP : Packet Data Convergence Protocol RLC: Radio Link Control MAC: Medium Access Control HARQ : Hybrid Automatic Repeat Request QoS : Quality of Service 20
10 2013-09-05
PDCP overview
Functions Header compression/ decompression of user plane data
Security Ciphering and deciphering for user plane and control plane data Integrity protection and verification for control plane data
Handover support In-sequence delivery and reordering of upper layer PDUs at handover Lossless handover for user plane data mapped on RLC Acknowledge Mode (AM)
Discard for timeout user plane data * 3GPP TS 36.323 v11.2.0: “Evolved Universal Terrestrial Radio Access (E-UTRA); Packet Data Convergence Protocol (PDCP) specification”(Release 11), April, 2013 21
Header Compression
Robust Header Compression (ROHC) Introduced RFC3095 and RFC 4815 Increase channel efficiency by reducing overhead Robust at unreliable link Three different mode : Unidirectional mode(U-mode), Bidirectional Optimistic mode(O-mode), and Bidirectional Reliable mode(R-mode) Compression example VoIP (in the active period) • payload 5,11~32 bytes ([email protected]~12.2kbps)+ header 40/60 bytes (RTP 12+UDP 8+IPv4 20/IPv6 40) payload 32 bytes + header 4~6 bytes
Sender Receiver Payload RTP UDP IP IP RTP UDP Payload
RoHC Context RoHC Context Compressor Compressor De-Compressor De-Compressor Compressed Header Payload H Framing/Error Detection Framing/Error Detection
Wireless Link 22 . acticom mobile networks, http://www.acticom.de/en/
11 2013-09-05
Header Compression
Header Fields Classification 0 15 31 Ver* ToS< Flow ID** Type Description Next Length” Header* Hop Limit< Inferred” They are never sent and they can IPv6 Source Address** be known by other component in the header Destination Address** Static* Send only once, their values Source Port** Destination Port** UDP never change during the stream Length” Checksum< Ver^ P* E* CCnt< M< P.Type< Sequence Number<
Static- Send only once, they give the Timestamp< def** definition of the stream Source Synchronization Indentification(SSRC)** RTP Source Contribution Identification (1st)< Static- They are never sent and their known^ values are known Contributing source (CSRC)< Changing< Header fields with a changing Source Contribution Identification (last)< value. The change can be periodic or randomly. They are Application Data always send 23
Header Compression
Header Fields Classification
Type Description Inferred” They are never sent and they can be known by other component in the header Static* Send only once, their values never change during the stream
Static- Send only once, they give the def** definition of the stream 1 byte ROHC header Static- They are never sent and their 3~5 bytes known^ values are known Static Info Changing< Header fields with a changing value. The change can be periodic or randomly. They are Application Data always send 24
12 2013-09-05
Header Compression
ROHC compression with U,O,R operation mode
25
Security
LTE security distribution NAS security Carried out for NAS messages / between UE and MME NAS messages are integrity protected and ciphered with extra NAS security header AS security (PDCP) Carried out for RRC and user plane data / between UE and eNB RRC messages are integrity protected and ciphered U-plane data is only ciphered
26 . 3GLTEINFO, http://www.3glteinfo.com/lte-security-architecture-20110325/
13 2013-09-05
Security
Ciphering Prevent unauthorized user from seeing the content of communication For control plane (RRC) data and user plane data PDCP Control PDUs (ROHC feedback and PDCP status reports) are not ciphered Integrity protection Used to detect whether a text is tampered during delivery Control plane (RRC) data For RN, User plane data 32-bit Message Authentication Code for Integrity (MAC-I)
27
Discard of Data Packets
To prevent excessive delay and queuing in the transmitter Discard Timer Related to buffer/delay management Defines maximum wait time Process When a PDCP SDU is received from upper layer, discard timer for the SDU is started When a discard timer expires, either the PDCP SDU is discarded or indication is sent to lower layer
28
14 2013-09-05
PDCP PDU format
PDCP Data PDU User plane PDCP Data PDU Long PDCP SN (12bits) (DRBs mapped on RLC AM or UM) Short PDCP SN (7bits) (DRBs mapped on RLC UM) Integrity protection for RN user plane (DRBs mapped on RLC AM or RLC UM) Extended PDCP SN (15 bits) (DRBs mapped on RLC AM) Control plane PDCP Data PDU For control plane SRBs D/C SN or Type MAC-I Data O SN (7,12, 15 bits) Δ PDCP Control PDU (DRB) Data XSN (5 bits)O Interspersed ROHC feedback packet (SRB) DRBs mapped on RLC AM or RLC UM ROHC OTypeX Status report feedback Status DRBs mapped on RLC AM OTypeX Report
* 3GPP TS 36.323 v11.2.0: “Evolved Universal Terrestrial Radio Access (E-UTRA); Packet Data Convergence Protocol (PDCP) specification”(Release 11), April, 2013 29
PDCP PDU format
PDCP Data PDU
15 2013-09-05
PDCP PDU format
PDCP Control PDU
User Plane Protocol Packet Data Convergence Protocol Radio Link Control Medium Access Control
32
16 2013-09-05
RLC Overview
Radio Link Control(RLC) Located between RRC/PDCP and MAC Error correction through ARQ Segmentation/Concatenation/Reassembly of RLC SDUs 3 transfer modes TM (Transfer Mode) • Only used for RRC messages which do not need RLC configuration • through BCCH, DL/UL CCCH and PCCH UM (Unacknowledged Mode) • Utilized by delay-sensitive and error-tolerant real-time applications • through DL/UL DTCH, MCCH or MTCH AM (Acknowledged Mode) • Utilized by error-sensitive and delay-tolerant non-real-time applications • through DL/UL DCCH or DL/UL DTCH
SDU: Service Data Unit BCCH: Broadcast Control Channel CCCH: Common Control Channel PCCH: Paging Control Channel DTCH: Dedicated Traffic Channel MCCH: Multicast Control Channel MTCH: Multicast Traffic Channel DCCH: Dedicated Control Channel 33
TM RLC entity
Features No segmentation/ No concatenation No RLC headers Deliver TMD PDUs Only for RRC messages which do not need RLC configuration SI messages Paging messages RRC messages which are sent when no SRBs other than SRB0
< Model of TM RLC entity > BCCH : Broadcast Control Channel PCCH : Paging Control Channel SRB: Signaling Radio Bearer 34 CCCH : Common Control Channel SI: System Information TMD: Transparent Mode Data
17 2013-09-05
UM RLC entity
Features Segment or concatenate RLC SDUs Add or remove RLC headers Reorder received RLC PDUs Reassembly of RLC SDUs Used by delay-sensitive and error-tolerant real-time applications VoIP, MBMS
concatenation
< Model of UM RLC entity > DTCH : Dedicated Traffic Channel MCCH : Multicast Control Channel SDU: Service Data Unit MTCH : Multicast Traffic Channel MBMS: Multimedia Broadcast/Multicast Service 35 UMD: Unacknowledged Mode Data
UM data transfer
36 < Example of PDU loss detection with HARQ reordering >
18 2013-09-05
AM RLC entity
Features Similar function of UM RLC entity Support ARQ (Stop and Wait) Detect the loss of AMD PDU and request retransmission to peer Deliver AMD PDU, AMD PDU segment and STATUS PDU Used by error-sensitive and delay-tolerant non-real-time applications Interactive/background type services: Web-browsing, file downloading
< Model of AM RLC entity >
37 ARQ: Automatic Repeat reQuest
AM data transfer
Retransmission and resegmentation Status reports from receiving side ACK/NACK RLC data PDU is stored in retransmission buffer Resegment the original RLC PDU into smaller PDU segments
< Example of RLC re-segmentation > 38
19 2013-09-05
Data flow through L2 protocol stack
A. Larmo et al., "The LTE link-layer design," Communications Magazine, IEEE , April 2009. 39
User Plane Protocol Packet Data Convergence Protocol Radio Link Control Medium Access Control
40
20 2013-09-05
MAC overview
Functions Channel Mapping Building MAC PDU Random access Scheduling Power saving by Discontinuous Reception(DRX) Error correction through HARQ Multiplexing / Demultiplexing Transport Format Selection Priority handling Logical Channel prioritization
Logical channel name Type Acronym Transport channel name Direction Acronym Broadcast Control Channel Control BCCH Broadcast Channel Downlink BCH Paging Control Channel Control PCCH Downlink Shared Channel Downlink DL-SCH Common Control Channel Control CCCH Paging Channel Downlink PCH Dedicated Control Channel Control DCCH Multicast Channel Downlink MCH Multicast Control Channel Control MCCH Uplink Shared Channel Uplink UL-SCH Dedicated Traffic Channel Traffic DTCH Random Access Channel Uplink RACH Multicast Traffic Channel Traffic MTCH • 3GPP TS 36.300 V11.5.0, "E-UTRA and E-UTRAN; Overall description; Stage 2(Release 11)", Mar, 2013. • 3GPP TS 36.300 V11.6.0, “E-UTRA and E-UTRAN; Overall description”, June, 2013. 41
Channel Mapping in LTE
42
21 2013-09-05
Downlink Channel Mapping(MAC-PHY)
MAC
PHY
•PxxCH : Physical xx Channel •PDCCH(Physical Downlink Control Channel) •PHICH(Physical HARQ Indicator Channel) 43
Uplink Channel Mapping(MAC-PHY)
MAC
PHY
44 •PUCCH(Physical Uplink Control Channel)
22 2013-09-05
Logical Channels
Control Channel Description
Broadcast Control Channel . Broadcasting system control information (BCCH) Paging Control Channel . Transfers paging information and system information change notifications (PCCH) . Used for paging when the network does not know the location cell of the UE. Common Control Channel . Transmitting control information between UEs and network (CCCH) . For UEs having no RRC connection with the network. Multicast Control Channel . A point-to-multipoint downlink channel (MCCH) . Transmitting MBMS control information from the network to the UE, for one or several MTCHs . Only used by UEs that receive or are interested to receive MBMS. Dedicated Control Channel . A point-to-point bi-directional channel (DCCH) . Transmits dedicated control information between a UE and the network . Used by UEs having an RRC connection.
Traffic Channels Description
Dedicated Traffic Channel (DTCH) . A point-to-point channel, dedicated to one UE . Transfer of user information . Exists in both uplink and downlink. Multicast Traffic Channel (MTCH) . A point-to-multipoint downlink channel for transmitting traffic data from the network to the UE . Only used by UEs that receive MBMS 45
Transport Channels
Downlink Channels Description Broadcast CHannel (BCH) . Transport the parts of the SI Downlink Shared CHannel . Transport downlink user data or control messages (DL-SCH) . Transport remaining parts of the SI that are not transported via the BCH Paging CHannel (PCH) . Transport paging information . Inform UEs about updates of the SI and PWS messages Multicast CHannel (MCH) . Transport MBMS user data or control messages that require MBSFN combining
Uplink Channels Description Uplink Shared Channel . Transport uplink user data or control messages (UL-SCH) Random Access Channel . Access to the network when the UE does not have (RACH) accurate uplink timing synchronization or UE does not have any allocated uplink transmission resource
46
23 2013-09-05
LTE Radio Frame Structure
Type 1 : for FDD Radio frame(10ms) = 10 subframes(1ms) = 20 slots(0.5ms) 10 subframes for downlink, 10 subframes for uplink Uplink and downlink transmissions are separated in the frequency domain Data is split into TTI blocks of T=1ms (one subframe)
47
LTE Downlink Subframe Structure (for Type 1) 1 Slot Consists 7 symbols
Resource Block 1 slot X 12 subcarriers =84 REs BPSK(1/2): 42bits 64QAM(3/4): 378bits
Resource Element Amount of data in a symbol in a subcarrier BPSK(1/2): 0.5bits 64QAM(3/4): 4.5bits
48
24 2013-09-05
LTE Radio Frame Structure
Type 2 : for TDD radio frame(10ms) = 2 half-frames(5ms) = 8 subframes(1ms) + 2 special subframes (DwPTS, GP, UpPTS) Subframe 1 always consists special fields, although subframe 6 is by configuration One radio frame =10 ms • DwPTS : Downlink Pilot Time Slot One half frame =5 ms • GP : Guard Period • UpPTS : Uplink Pilot Time Slot
1 ms
# 0 # 2 # 3 # 4 # 5 # 7 # 8 # 9
DwPTSGP UpPTS DwPTSGP UpPTS
Uplink(U)/Downlink(D)/Special frame(S) Allocation Switch-poi Subframe number Configu nt periodi ration 0 123456789 city 05 msDSUUUDSUUU 15 msDSUUDDSUUD 25 msDSUDDDSUDD 310 msDSUUUDDDDD 410 msDSUUDDDDDD 510 msDSUDDDDDDD49 65 msDSUUUDSUUD
Building MAC PDU(MAC PDU Format)
MAC PDU = MAC Header + MAC Payload MAC subheader Logical Channel ID (LCID), Length(L) field MAC control element Used for MAC-level peer-to-peer signaling Buffer status report / UE’s available power headroom in uplink/ DRX command, etc. Headerless MAC PDU MAC PDU constructed without header Use it when MAC PDU is used to transport data from the PCCH or BCCH PCCH or BCCH : one-to-one corresponding between MAC SDU and MAC PDU
50
25 2013-09-05
Random Access(RA) Procedure
Purpose RA is performed when UE didn’t assigned resource for data transmission
Contention based Perform when eNB doesn’t know the presence of UE or UE have data to transmit while UE lost timing information Examples • Initial access from RRC_IDLE • RRC Connection Re-establishment procedure • UL data arrival during RRC_CONNECTED requiring random access procedure »E.g. when UL synchronisation status is "non-synchronised" or there are no PUCCH resources for SR available
Non-contention based Perform when eNB know the incoming of UE or eNB have data to transmit while UE lost timing information Examples • Handover • For positioning purpose during RRC_CONNECTED requiring RA • DL data arrival during RRC_CONNECTED requiring random access procedure »E.g. when UL synchronisation status is “non-synchronised”
51
Random Access Procedure - Contention based(1) (0) Selection of preamble : select a preamble in preamble groups
Preambles for contention based access Preambles for (2 groups, select a group by message size) contention-free access
Total 64 preambles(spreading codes) in each cell (1) Preamble Transmission on RACH • Set transmission power : according to DL estimation on RSRP • Power ramping : increase transmission power by number of retrials
(2) RA Response (PDCCH tagged with RA-RNTI + PDSCH) • Send response for a UE if single preamble is detected • This message includes UL resource grant, timing alignment information for sending third message • Assign a temporary ID for UE(TC-RNTI) • No RA Response for UE Backoff Back to Selection of preamble • RSRP : Reference Signal Received Power •TC-RNTI : Temporary Cell Radio Network Temporary Identifier • RA-RNTI : Random Access Radio Network Temporary Identifier 52
26 2013-09-05
Random Access Procedure - Contention based(2)
(3) First PUSCH TX – Includes TC/C-RNTI
• Conveys actual random access procedure message • If multiple UEs selected same RACH and preamble in (1), collision occurs • No collision eNB detects one C-RNTI and get message from PUSCH
(4) Contention Resolution on DL • UE considers as success, and TC-RNTI is promoted to C-RNTI • If (3) is collided No arrival of Contention Resolution for UE Backoff Back to Selection of preamble
53
Random Access Procedure - Non-Contention based
(0) RA Preamble Assignment • eNB assigns to UE a non-contention Random Access Preamble before RA(ex> before handover)
(1) RA Preamble • Transmits non-contention RA Preamble
(2) RA Response • Conveys at least timing alignment information and initial UL grant for handover, timing alignment information for DL data arrival, RA- preamble identifier
54
27 2013-09-05
Data Transmission after RA - Downlink Scheduling(1) Dynamic Scheduling Signal and transmit data without periodicity Signaling is required at each transmission
Signaling for dynamic scheduled data
•PDCCH(Physical Downlink Control Channel) •DL-SCH(Downlink Shared Channel) 55
Data Transmission after RA - Downlink Scheduling(2) Semi-persistent scheduling Schedule periodical transmission Only the one signaling at first transmission is required Reduce signaling overhead Scheduling periodicity is configured by RRC
Signaling for semi-persistent data No additional signalling for semi- (example : period = 4) persistent scheduled data
56
28 2013-09-05
Data Transmission after RA - Uplink Scheduling Procedure eNodeB notifies the TX slot which can be used by UE for uplink transmission UE sends data through UL-SCH and activates HARQ process HARQ mechanism : Stop-and-Wait eNodeB signals transmission result by HARQ ACK/NACK to UE For NACK, eNodeB schedule for retransmission through PDCCH
• Example for N=4 : UE/eNB response after 4 subframe Subframe
•PDCCH(Physical Downlink Control Channel) •UL-SCH(Uplink Shared Channel) •PHICH(Physical HARQ Indicator Channel) 57
Wireless Packet Scheduling Algorithm • Additional Slides Features of Scheduling Algorithms for Wireless Network Each user experience different transmission speed Channel environment differ by randomly through time Bursty error occurs User’s channel capacity changes by fading Require to estimate channel environment
58
29 2013-09-05
Signaling for Resource Allocation • Additional Slides For resource allocation, eNodeB requires… Channel Quality Information(frequency specific) Traffic information(volume and priority, queue status
Signaling tradeoff Data rate ↔ Overhead
CQI measurement DL : through the feedback of CQIs by UEs UL : by Sounding Reference Signals(SRS) transmitted by UE to estimate ch. quality Frequency of the CQI reports is configurable Reduce overhead ↔ Accuracy
Information about queue status DL : directly available at eNB UL : specific reporting mechanism
59
Scheduling Algorithms • Additional Slides Opportunistic algorithm / High Rate User First (HRUF) Simplest algorithm considering wireless channel Optimizing the total throughput Assign resources to user with best CQI Fairness problem occurs If the an user with best channel continuously generates traffic, then other users cannot be assigned wireless resource Other users cannot transmit their traffic Fairness and QoS are not assured
maxi (t )
i ()t : Maximum transmission rate of user i
60
30 2013-09-05
Scheduling Algorithms • Additional Slides Fair algorithms Minimize UE latency Ex. Min-Max : Maximizes the minimum allocated rate
max min{i (t )} i Total Throughput reduced
61
Scheduling Algorithms • Additional Slides Proportional Fair Share Scheduling (PFSS) Algorithm Maximize Throughput with some degree of fairness Algorithm Basically, schedule UE when its instantaneous channel quality is high relative to its own average channel Reduce priority of UE by volume of received traffic increase fairness
()t ()tSNRmf log 1 ( , ) max i ik2 ˆ ()t i Te : Estimation interval 1served rate in slot (-1) t m : resource block ()tt 1- ( -1) f : subframe TTee
Large Te tends to maximize the total average throughput Small Te tends to maximize fairness
62
31 2013-09-05
Retransmission – HARQ
Downlink : Asynchronous adaptive HARQ Asynchronous Retransmission with additional explicit signaling to indicate the HARQ process number to the receiver Adaptive HARQ Modulation and coding scheme(MCS), resource allocation can be changed Non-adaptive HARQ : retransmit with previous MCS and resource
63
Retransmission – HARQ
Uplink : Synchronous HARQ PDCCH Non-adaptive/adaptive feedback seen seen by UE behaviour HARQ by the UE the UE ACK New New transmission according Uplink : Synchronous HARQ or NACK Transmission to PDCCH Synchronous ACK Retrans- Retransmission according to • Retransmission occur at or NACK mission PDCCH(adaptive retransmission) predefined times relative to the No (re)transmission initial transmission to reduce ACK None PDCCH is required to resume control signaling Retransmissions NACK None Non-adaptive retransmission
ACK / PHICH NACK PDCCH Grant Grant
New/ UL-SCH Data ReTx Data 64
32 2013-09-05
Retransmission – HARQ
HARQ type HARQ combines FEC and ARQ Three types HARQ Type I HARQ • Chase combining » Initial transmission and retransmission have same puncturing pattern
65
Retransmission – HARQ
HARQ type HARQ combines FEC and ARQ Three types HARQ Type II HARQ • Incremental redundancy » The information bits does not retransmitted » The retransmitted packet has different puncturing pattern
66
33 2013-09-05
Retransmission – HARQ
HARQ type HARQ combines FEC and ARQ Three types HARQ Type III HARQ • Incremental redundancy » Initial transmission and retransmission have different puncturing pattern » Information bits will be retransmitted
67
Power Saving/Fast Wake-up – Discontinuous Reception(DRX) Power saving in UMTS Through the state change from CELL_DCH to IDLE_MODE Fast recovering to CELL_DCH takes undesired delay
•DCH (Dedicated Channel) •FACH (Forward access channel) •PCH (Cell Paging channel) 68 •URA_PCH (URA Paging channel).
34 2013-09-05
Power Saving/Fast Wake-up – Discontinuous Reception(DRX) Power Saving in LTE/LTE-Advanced : Discontinuous Reception(DRX) Power saving with maintaining connected states When need power saving Change to DRX mode while maintain RRC_CONNECTED state UE can fast wake-up, because it maintain connectivity with eNodeB
• DRX UE only listens at certain Intervals RRC_CONNECTED • DRX reduced battery consumption • DRX resume transfer even quicker • DRX reduced signaling
RRC_IDLE
69
Power Saving/Fast Wake-up – Discontinuous Reception (DRX) UE does not monitor the downlink channels during such DRX period HARQ Round Trip Time (RTT) Short cycle, Long cycle Wake-up and check downlink during “on duration” only By two timer, control wake-up interval(=short DRX cycle and long DRX cycle)
① ④ ⑥ enter short DRX mode enter long DRX mode
③
②⑤Activate Activate Inactivity timer Short DRX Cycle Timer 70
35 2013-09-05
Control Plane Protocol
71
Control Plane Protocol Overview
UE eNB MME S1-MME(logical interface) NAS NAS
RRC RRC S1-AP S1-AP
PDCP PDCP SCTP SCTP
RLC RLC IP IP
MAC MAC MAC MAC
PHY PHY PHY PHY
LTE-Uu (radio interface) Non-access stratum Access stratum control plane PLMN selection radio-specific functionalities Tracking area update The AS interacts Paging with the NAS (upper layers) Authentication EPS bearer establishment, modification and release RRC: Radio Resource Control PDCP: Packet Data Convergence Protocol 72 RLC: Radio Link Control PLMN: Public Land Mobile Network EPS: Evolved Packet System
36 2013-09-05
Control Plane Protocol Overview : NAS Overview Highest stratum of c-plane (UE <-> MME) S1-MME (eNB – MME) Main functions EPS mobility management UE mobility EPS session management IP connectivity between the UE and a P-GW Security integrity protection and ciphering of NAS signaling messages.
. 3GPP TS 24.301 V10.7.0 “UMTS; LTE; NAS; EPS; Stage 3”, July, 2012 73 . 3GPP TS 24.401 V8.9.0 “ LTE; GPRS enhancements for E-UTRAN access”, March, 2010
Control Plane Protocol Overview : RRC Overview AS of c-plane (UE <-> eNB) LTE-Uu interface Main functions Broadcast SI related to NAS and AS Paging Establishment of an RRC connection (UE<->E-UTRAN) Security functions (key management) Establishment of p-to-p Radio Bearers Mobility functions QoS management functions UE measurement reporting NAS direct message transfer (NAS<->UE)
74 . 3GPP, "TS 36.331 V10.5.0 Radio Resource Control (RRC) Protocol specification (Release 10)," ed, 2012.
37 2013-09-05
NAS/RRC State
Protocol State Description EMM-Deregistered • UE is detached • No EMM context has been established in UE and MME. EMM-Registered • UE has been attached • IP has been assigned • An EMM Context has been established • A default EPS Bearer has been activated NAS • The MME knows the location of the UE(TA). (UE,MME) ECM-Idle • No NAS signalling connection (ECM connection) • No UE context held in E-UTRAN(eNB) • The MME knows the location of the UE(TA) ECM-Connected • NAS signalling connection (ECM connection; a RRC connection & a S1 signalling connection) • The MME knows the location of the UE(cell) RRC RRC-Idle • RRC connection has not been established. (UE,eNB) RRC-Connected • RRC connection has been established.
TA: Tracking Area EMM: EPS Mobility Management ECM: EPS Connection Management MME: Mobility Management Entity 75 1. Netmanias, “EMM and ECM States,” http://www.netmanias.com, 2013.
NAS/RRC State
When UE is switched on for the first time after subscription When UE is switched on after a long time after the power has been turned off There exists no UE context in the UE and MME.
76
38 2013-09-05
NAS/RRC State
When UE is switched on within a certain period of time after the power has been turned off When ECM connection is released during communication due to radio link failure Some UE context can still be stored in the UE and MME (e.g., to avoid running an AKA procedure during every attach procedure).
77
NAS/RRC State
When UE is attached to the network (MME) and using services The mobility of UE is handled by handover
78
39 2013-09-05
NAS/RRC State
79
NAS/RRC State
When UE is attached to the network (MME) and not using any service
80
40 2013-09-05
NAS/RRC State
81
Control Plane Protocol Overview : RRC States RRC_IDLE RRC_CONNECTED UE known in EPC and has IP UE known in EPC and E- address UTRAN/eNB UE location known on Tracking UE location known on cell level Area level Unicast data transfer is possible Paging in TA controlled by EPC eNB-based mobility UE-based cell-selection and TA DRX supported for power update saving
2.
3.
5.HO 82
41 2013-09-05
Control Plane Protocol Overview : UE Operation in RRC States RRC_IDLE RRC_CONNECTED Monitors a paging channel Monitors a Paging channel incoming calls and/or SIB1 system information change detect system information change ETWS, CMAS Monitor control channels measurement associated and data channel cell (re-)selection Provide channel quality and Acquire system information feedback information (MIB, SIBs) measurement and reporting Acquire system information
DRX: Discontinuous Reception ETWS: Earthquake and Tsunami Warning System 83 CMAS: Commercial Mobile Alert Service
Control Plane Protocol Overview : UE Camping Procedure
(1) PLMN selection Read USIM (10) Service Obtained NAS Read stored info on ME (Camped) Select Band, PLMN, etc
(6) Process SIB1 Check PLMN Is Cell reserved? (2) Trigger (4) Schedule Is CSG Id valid? (8) All SIBs RRC System Broadcast Control Cell belong to Forbidden TA? obtained Acquisition Channel read Cell barred? If fail, go back to (3) AS If ok, go to (7)
(9) Cell is (3) Acquisition (5) Read MIB/SIB1 PHY (7) SIB2 and Other SIBs Selected and Scan Band/Freq Using SI-RNTI UE camps
84 . Bong Youl (Vrian) Cho, “LTE RRC/RRM”, TTA LTE/MIMO Standards/Technology Trainning, May 2012
42 2013-09-05
RRC Services
Services provided to upper layers Broadcast of common control information Notification of UEs in RRC_IDLE receiving call, ETWS, CMAS Transfer of dedicated control information information for one specific UE Services expected from lower layers PDCP Integrity protection and ciphering RLC Reliable and in-sequence transfer of information • without introducing duplicates • with support for segmentation and concatenation
85 ETWS: Earthquake and Tsunami Warning System CMAS: Commercial Mobile Alert Service
RRC Functions
. NAS common information . For UEs in RRC_IDLE • Cell (re-)selection parameters Broadcast of system information • Neighboring cell information . For UEs in RRC_CONNECTED • Common channel configuration information . Paging . Establishment/modification/release of RRC connection or DRBs . Initial security activation RRC connection control . RRC connection mobility . Radio configuration control (ARQ, HARQ, DRX) . QoS control . Recovery from radio link failure . Security activation Inter-RAT mobility . Transfer of RRC context information . Establishment/modification/release of measurements Measurement configuration control . Setup and release of measurement gaps and reporting . Measurement reporting . Dedicated NAS information Transfer of information . Non-3GPP dedicated information . UE radio access capability information . Generic protocol error handling Others . Support of self-configuration and self-optimization 86
43 2013-09-05
Connection Control
Security activation Ciphering of both control plane RRC data (SRBs 1 and 2) and user plane data (all DRBs) Integrity protection which is used for control plane data only Connection establishment, modification and release DRB establishment, modification and release
87 SRB: Signaling Radio Bearers DRB: Date Radio Bearers
Connection Establishment and Release
88
44 2013-09-05
DRB Establishment : Signaling Radio Bearers SRB: radio bearers that are used only for the transmission of RRC and NAS messages SRB0 For RRC messages Using the CCCH logical channel SRB1 For RRC messages (which may include a piggybacked NAS message) For NAS messages prior to establishment of SRB2 All using DCCH logical channel SRB2 For NAS messages Using DCCH logical channel Lower-priority than SRB1 Always configured by E-UTRAN after security activation
89 CCCH: Common Control Channel DCCH: Dedicated Control Channel
DRB Establishment : Signaling Radio Bearers An EPS bearer is mapped (1-to-1) to a DRB A DRB is mapped (1-to-1) to a DTCH logical channel All logical channels are mapped (n-to-1) to the DL-SCH or UL-SCH DL-SCH or UL-SCH are mapped (1-to-1) to the corresponding PDSCH or PUSCH
90
45 2013-09-05
Mobility Control
Criteria for cell selection or reselection Radio link quality: primary criterion UE capability Subscriber type Cell type E-UTRAN provides a list of neighboring frequencies and cells; white-list or black-list
91
Mobility in RRC_IDLE : PLMN and Cell Selection PLMN selection The NAS handles PLMN selection based on a list of available PLMNs provided by the AS Cell selection (EMM-DEREGISTERED) The UE searching for the strongest cell on all supported carrier frequencies of each supported RAT Using NAS’s support and stored information from a previous access Requirement: not take too long Cell reselection (EMM-REGISTERED) Move the UE to the best cell of the selected PLMN
92
46 2013-09-05
Mobility in RRC_IDLE : Cell Reselection
RRC_IDLE Mobility
Measurement and evaluation of serving cell
Measurement of neighbour cells
Evaluation of neighbour cells for cell reselection
Acquisition of the system information of the target cell
Cell reselection to the target cell
93
Mobility in RRC_IDLE : Cell Selection Criteria Cell selection: received level & quality Srxlev & Squal Srxlev rxlevmeas rxlevmin rxlevminoffset Squal qualmeas qualmin qualminoffset rxlevmeas: Measured cell RX level value (RSRP) qualmeas: Measured cell quality value (RSRQ) rxlevmin: Minimum required RX level in the cell (dBm), in SIB1 qualmin: Minimum required quality level in the cell (dB), in SIB1 rxlevminoffset, qualminoffset: offsets which may be configured to prevent ping-pong between PLMNs, in SIB1
94
47 2013-09-05
Mobility in RRC_CONNECTED
95
Mobility in RRC_CONNECTED : Handover
UE Source eNB Target eNB
Measurement Report
Handover Preparation UE RRC context information (UE capabilities, current AS- configuration, UE-specific RRM information Handover command RRCConnectionReconfiguration information for random access(mobility control, radio resource configuration), dedicated radio resource security configuration, C-RNTI
Random access procedure RRCConnectionReconfigurationComplete
96
48 2013-09-05
Mobility in RRC_CONNECTED : Handover Handover from Macro cell to macro cell HO triggering condition UE satisfies A3 condition during TTT -> HO request to S-eNB -> HO execution
HO delay TTT Hyst + offset
• H/O completion
• A3 satisfaction • HO execution 97
Mobility in RRC_CONNECTED : Seamless Handover Seamless handover OBJECTIVE : Interruption Time Minimization Used for all RBs carrying control plane data and user plane data mapped on RLC UM Loss tolerant and delay sensitive eNB forwards only non-transmitted SDUs via X2 to target eNB If transmission was started but has not been successfully received packets are lost Minimum complexity because context is not transferred between eNB via X2 ROHC, COUNTS context is reset
98 . 3GPP TS 36.323, “E-UTRA; PDCP specification.”
49 2013-09-05
Mobility in RRC_CONNECTED : Seamless Handover Seamless handover in the downlink SDUs are transmitted to eNB in sequence
손실된 패킷은 재전송 되지 않 음
전송하지 못한 패킷은 X2로전 달
Reordering은 UE가수행
99 . 3GPP TS 36.323, “E-UTRA; PDCP specification.”
Mobility in RRC_CONNECTED : Lossless Handover Lossless handover OBJECTIVE : In-Sequence Delivery without Losses Possible because PDCP adds a sequence number to packets Applied for radio bearers that are mapped on RLC-AM Delay-tolerant and loss-sensitive Un-acknowledged packets are forwarded via X2 an retransmitted they may be received twice ROHC context is reset
100 . 3GPP TS 36.323, “E-UTRA; PDCP specification.”
50 2013-09-05
Mobility in RRC_CONNECTED : Lossless Handover Lossless handover in the uplink SDUs are delivered to the GW in sequence
Serving eNB transfers via X2, out-of-sequence SDUs
STATUS TRANSFER contains Sequence and Hyper Frame Numbers
Unacknowledged SDUs are retransmitted duplicity of P4
101 . 3GPP TS 36.323, “E-UTRA; PDCP specification.”
Mobility in RRC_CONNECTED : Lossless Handover Lossless handover in the downlink SGW transmits End Marker to serving eNB
Target eNB knows when it can start to transmit SDUs from SGW
SDUs are delivered to the UE in sequence
102 . 3GPP TS 36.323, “E-UTRA; PDCP specification.”
51 2013-09-05
Mobility in RRC_CONNECTED : Detailed Handover Procedure (1/3) S1-Based handover Control Admission
103
Mobility in RRC_CONNECTED : Detailed Handover Procedure (2/3)
104
52 2013-09-05
Mobility in RRC_CONNECTED : Detailed Handover Procedure (3/3)
UE Source eNB Target eNB MME Serving GW
Step 1: HO Preparation Step 2: HO Execution
Switch DL Path
Packet data Packet data
Resource Resource
Measurements
Measurement Configuration: RRCConnectionReconfiguration message Measurement objects: carrier frequency or list of cells Reporting configurations: RSRP/RSRQ, number of cells Measurement identities Quantity configurations: filtering Measurement gaps: time periods
UE may measure and report Serving cell Listed cells Detected cells on a listed frequency
106 RSRP: Reference Signal Received Power RSRQ: Reference Signal Received Quality
53 2013-09-05
Measurements : Measurement report triggering
Event Condition
A1 Serving becomes better than threshold:
A2 Serving becomes worse than threshold:
Neighbor becomes offset better than Pcell: A3
A4 Neighbor becomes better than threshold:
PCell becomes worse than threshold1 and neighbor becomes better than threshold2: A5 1 & 2
A6 Neighbour becomes offset better than SCell: (Rel-10)
B1 Inter RAT neighbor becomes better than threshold:
PCell becomes worse than threshold1 and inter RAT neighbor becomes better than B2 threshold2: 1 & 2
Mserving/Mn/Mp/Ms: measurement result of serving cell/neighbor cell/Pcell/SCell Of/Oc: frequency/cell specific offset PCell: Primary (serving) Cell SCell: Secondary (serving) Cell <- carrier aggregation 107 . 3GPP, "TS 36.331 V10.5.0 Radio Resource Control (RRC) Protocol specification (Release 10)," ed, 2012.
Measurements : Reference Signal Received Power RSRP UEs measure RSRP over the cell-specific RSs Periodic measurement Intra-freq.: 200ms Inter-freq.: 480ms (proportion to the DRX cycle) Requirements intra-frequency: 8 cells inter-frequency: 4 cells * 3 carriers = 12 cells
108
54 2013-09-05
Measurements : Reference Signal Received Quality Reference Signal Received Quality (RSRQ) RSRQ ∝ RSSI the total received power • interference from all sources • serving and nonserving cells • adjacent channel interference and thermal noise LTE Rel-8 RSRQ was applicable only in RRC_CONNECTED state • Handover LTE Rel-9 RSRQ was also introduced for RRC_IDLE • Cell reselection
109 RSSI : Received Signal Strength Indicator
Measurements : System Information Blocks SIB Contents
MIB • parameters which are essential for a UE’s initial access to the network
• parameters needed to determine if a cell is suitable for cell selection SIB1 • information about the time-domain scheduling of the other SIBs
SIB2 • common and shared channel information
• parameters used to control intra-frequency, inter-frequency and inter- SIB3-8 RAT cell reselection
SIB9 • signal the name of a Home eNodeB (HeNBs)
SIB10-12 • ETWS notifications and CMAS warning messages
SIB13 • MBMS related control information
ETWS: Earthquake and Tsunami Warning Service CMAS: Commercial Mobile Alert System 110 MBMS: Multimedia Broadcast/Multicast Services
55 2013-09-05
Measurements : RRC messages to transfer SI (example) MIB(SIB1) message is carried by PBCH(PDSCH) created every 40(80) msec broadcasted every 10(20) msec Other SI messages are created and broadcasted dynamically on the PDSCH
Message Content Period Applicability MIB Most essential parameter 40 ms Idle/connected SIB1 Cell access related parameters, scheduling information 80 ms Idle/connected 1st SI SIB2: Common and shared channel configuration 160 ms Idle/connected 2nd SI SIB3: Common cell reselection information and intra-frequency cell 320 ms Idle only reselection parameters other than the neighbouring cell information SIB4: Intra-frequency neighbouring cell Information 3rd SI SIB5: Inter-frequency cell reselection information 640 ms Idle only 4th SI SIB6: UTRA cell reselection information 640 ms Idle only SIB7: GERAN cell reselection information PBCH: Physical Broadcast Channel PDSCH: Physical Downlink Shared Channel 111 SFN: System Frame Number
Paging
Paging UE eNB MME transmit paging Monitor PDCCH at certain UE-specific subframes
TA: Tracking Area PDCCH: Physical Downlink Control Channel RNTI: Radio Network Temporary Identifier 112 P-RNTI: Paging RNTI ETWS: Earthquake and Tsunami Warning service
56 2013-09-05
Paging : Tracking Area TAI: Global Unique ID PLMN ID + TAC In order to paging, MME needs TAI Ex) MME1 sends paging to UE1 => broadcast all the eNBs in TAI1 & TAI2 TAI list UE receives TAI list when it is connected TAU When UE move out from own TAI list Periodic TAU
113 TAI: Tracking Area Identifier TAC: Tracking Area Code TAU: Tracking Area Update
Radio Resource Management : RRM Functions Power control Scheduling Cell search Cell reselection Handover Radio link or connection monitoring Connection establishment and re-establishment Interference management Location services Self-Optimizing network (SON) Network planning
114
57 2013-09-05
Radio Resource Management : LTE RRM Characteristic Characteristics Details Interference fluctuation • Fast time and frequency domain scheduling Wide range of DRX • DRX: 0~2.5 sec • LTE, 3GPP & non-3GPP legacy RATs Different RATs • Different channel structure • Macro / femto / pico Various cell sizes • A few ‘m’ ~ tens of ‘km’ Various frame structure • FDD(synchronized or unsynchronized), TDD
• Measurements & reports Low latency requirements • HO
115 MBMS: Multimedia Broadcast/Multicast Service
Power Control
LTE power control is not as critical as in WCDMA LTE uplink resources are orthogonal -> no intra-cell interference (theory) frequency selective scheduling
Power Control Maximize system capacity Minimize inter-cell interference
116 SRSs: Sounding Reference Signals RB: Resource Block RE: Resource Element
58 2013-09-05
Power Control : UL Power Control Uplink power control: PUSCH, PUCCH and the SRSs (unit of RB) ∙ ∆ Semi-static basic open-loop operating point
: cell specific power level : factor to trade off the fairness of uplink scheduling against total cell capacity • PUCCH: always 1-> maximize fairness for cell edge UE : downlink pathloss estimate calculated in the UE dynamic offset updated from subframe to subframe
∆ : MCS dependent power offset : TPC command related power • TPC command: relative power offset comparing to its previous Tx power, or absolute power
SRSs: Sounding Reference Signals RB: Resource Block RE: Resource Element TPC: Transmitter Power Control . 3GPP, "TS 36.213 v10.6.0 LTE; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures 117 (Release 10)," July 2012.
Power Control PDSCH power to RS, : DL Power Allocation where NO RSs are present, is UE specific Downlink power allocation (unit of RE) and signaled by higher Cell specific RS EPRE (Energy per RE) layer as : semi-static (eNB signals UE) For PDSCH power in same symbol as RS an or additional cell specific PDSCH RE’s position (index 0, 4) offset is applied, that is signaled by higher layer 10log EPRE : 0dB for all transmission modes Cell-specific except multi-user MIMO RS power, signaled in : UE specific parameter SIB2 from higher layer : 2 (transmit diversity PDCCH with 4 antenna ports) power or 1 (otherwise) depending on / ∙ : cell specific parameter Subcarrier from higher layer Index RE: Resource Element . 3GPP, "TS 36.213 v10.6.0 LTE; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures 118 (Release 10)," July 2012.
59 2013-09-05
Cell Search
Cell Search UE acquires the carrier frequency, timing and cell identity of cells Cell search within E-UTRAN Identify one of the 504 unique Physical Cell Identities (PCIs) Requirements Maximum permissible cell identification delay(∝ DRX cycle) Minimum synchronization signal quality
: the energy per Resource Element (RE) of the synchronization signal
: total received energy of noise and interference on the same RE
Case Max. Delay Min. / Intra-frequency 800ms -6dB DRX (0~40ms) Inter-frequency 3.84s -4dB DRX(0~160ms) 119
Radio Link Failure Handling
1st phase Layer 1 monitors downlink quality and indicates problems to RRC RRC filters L1 indications and starts a timer if no recovery within 1st phase, triggers 2nd phase Layer 2 monitors random access attempts and indicates problems to RRC RRC triggers 2nd phase 2nd phase – Radio Link Failure (RLF): Possible recovery through an RRC Connection Reestablishment procedure reestablishment may be performed in any cell to which the UE’s context is made available If no recovery within 2nd phase, UE goes autonomously to IDLE
120
60 2013-09-05
Inter-Cell Interference
LTE is designed for frequency reuse 1 (To maximize spectrum efficiency) All the neighbor cells are using same frequency channels no cell-planning to deal with the interference issues Shared channels RB scheduled to cell edge user can be in high interference ->low throughput / call drops Control channels Neighbor interference -> radio link failures at cell edge.
121
Inter-Cell Interference Coordination
ICIC mitigates interference on traffic channels only Power and frequency domain to mitigate cell-edge interference from neighbor cells X2 interface is used to share the information between the eNBs
A.Neighbor eNBs use different sets of RBs improves cell-edge SINR decrease in total throughput B.Center users: complete range of RBs Cell-edge users: different sets of RBs C.Scheme B + different power schemes For center/cell edge user: low/high power 122
61 2013-09-05
Summary of Control Plane : Initial Attach Procedure Summary of Initial Attach Procedure
S-GW: Serving Gateway P-GW: Packet Data Network Gateway HSS: Home Subscriber Server PCRF: Policy and Charging Rule Function SPR: Subscriber Profile Repository IMSI: International Mobile Subscriber Identity . Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011 123 . http://www.netmanias.com/bbs/view.php?id=techdocs&no=74
Summary of Control Plane : Acquisition of IMSI Summary of Initial Attach Procedure
124 . Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011
62 2013-09-05
Summary of Control Plane : Acquisition of IMSI
GUMMEI: Globally Unique MME ID ECGI: E-UTRAN Cell Global Identifier TAI:Tracking Area Identity 125 . Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011
Summary of Control Plane : Authentication Summary of Initial Attach Procedure
126 . Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011
63 2013-09-05
Summary of Control Plane : Authentication
MCC: Mobile Country Code MNC: Mobile Network Code PLMN: Public Land Mobile Network ID PLMN=MCC+MNC 127 . Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011
Summary of Control Plane : NAS Security Setup Summary of Initial Attach Procedure
128 . Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011
64 2013-09-05
Summary of Control Plane : NAS Security Setup
129 . Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011
Summary of Control Plane : Location Update Summary of Initial Attach Procedure
130 . Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011
65 2013-09-05
Summary of Control Plane : Location Update
APN: Access Point Name QCI: QoS Class identifier ARP: Allocation and Retention Priority AMBR: Aggregated Maximum Bit Rate 131 . Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011
Summary of Control Plane : EPS Session Establishment Summary of Initial Attach Procedure
132 . Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011
66 2013-09-05
Summary of Control Plane : EPS Session Establishment (1)
TEID: Tunnel Endpoint ID 133 . Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011
Summary of Control Plane : EPS Session Establishment (2)
TEID: Tunnel Endpoint ID 134 . Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011
67 2013-09-05
Summary of Control Plane : EPS Session Establishment (3)
135 . Netmanias, “EMM Procedure: 1. Initial Attach for Unknown UE (2편),” September, 2011
Summary of Control Plane : EPS Session Establishment (4)
136
68 2013-09-05
Summary of Control Plane
137
LTE-Advanced Features Heterogeneous Networks Carrier Aggregation CoMP
138
69 2013-09-05
Heterogeneous Networks
Objective Coverage extension Interference mitigation Capacity increase Nodes Macro cells (eNBs) RRH (Remote Radio Head) Antenna extension with wired backhaul (Fiber) Small cells Tx power: 46 dBm Relay Perform a role of eNB in a UE perspective Wireless backhaul Tx power: 30 dBm Pico cells (Pico eNBs) Similar to macro eNBs but with lower power Wired backhaul (X2 interface) Tx power: 23-30 dBm Femto cells (HeNBs) CSG/OSG/Hybrid Indoor deployment by the customer usually without planning HeNB gateway can (optionally) be deployed to manage a large number of HeNBs (Rel-9/10) High speed internet access for backhaul Tx power: <23 dBm
CSG: Cell Subscriber Group OSG: Open Subscriber Group D Lopez-Perez, A Valcarce, G De La Roche, J Zhang, “Enhanced intercell interference coordination challenges in 139 heterogeneous networks”. IEEE Wirel Commun. 18(3), 22–30, 2011
Heterogeneous Networks
Core Network
Wireless Internet
High speed Internet X2 interface Fiber Macro Femto Pico Relay
RRH
Khandekar, A.; Bhushan, N.; Ji Tingfang; Vanghi, V., "LTE-Advanced: Heterogeneous networks," Wireless Conference 140 (EW), 2010 European , vol., no., pp.978,982, 12-15 April 2010
70 2013-09-05
Heterogeneous Networks :Hot issues for Small cell Networks Dual connectivity UE maintain connections with macro cell and small cell Macro cell manages the C-plane of UE connections Small cell manages only U-plane protocols of UE connections Mobility enhancement Lite handover algorithm to reduce handover overhead between macro cell and small cell User-centric cooperative handover scheme Interference handling Interference between macro cell and small cell, small cell and small cell Transmission power control of small cell according to amount of traffic Bandwidth sectoring for small cells
윤영우, “3GPP LTE Rel-12 & Onwards 주요 요소 기술 및 표준 동향”, 전자공학회지, 제 40권 4호, pp.328-339, 141 2013년 4월.
Heterogeneous Networks :Hot issues for Small cell Networks Cell discovery Efficient cell searching considering small cell interferences and plenty of cells Effective cell discovery considering unplanned small cells Improved spectral efficiency High modulation scheme (e.g. 256QAM) with high received power in small cells Reducing reference signal overhead
윤영우, “3GPP LTE Rel-12 & Onwards 주요 요소 기술 및 표준 동향”, 전자공학회지, 제 40권 4호, pp.328-339, 142 2013년 4월.
71 2013-09-05
Heterogeneous Networks :Current works Cloud-RAN* (삼성전자) Separate Digital Unit and Radio Unit in eNB CCC (Cloud control center) control multiple RRH Support CA, CoMP, ICIC(Inter-cell interference) Inter-eNB CA is an alternative to fiber based cloud-RAN
*3GPP, RWS-120046, Samsung Electronics, “Technologies for Rel-12 and Onwards,” June 2012. 143
Heterogeneous Networks :Current works Phantom cell* (NTT Docomo) Macro cell manages control signals for small cells Small cell manage only data transmission High bandwidth efficiency
*3GPP, RWS-120010, NTT DOCOMO, “Requirements, Candidate Solutions & Technology 144 Roadmap for LTE Rel-12 Onward,” June 2012.
72 2013-09-05
Heterogeneous Networks :Current works Soft Cell* (Ericsson & ST-Ericsson) Dual connectivity – anchor and booster carriers Logical connection on anchor and booster carrier Does not necessarily imply simultaneous UE physical-layer Rx/Tx of booster and anchor carrier(s)
Anchor carrier Booster carrier Macro node connection Pico node connection (when beneficial) System information, basic RRC Offloading of large data volumes Low-rate/high-reliability user data Ultra-lean transmissions, minimum amount of Based on Rel-8 – Rel-11 structures overhead
145 * 3GPP, RWS-120003, Ericsson & ST-Ericsson, “Views on Rel-12,” June 2012.
Heterogeneous Networks :Current works Hyper-dense LTE network* (Qualcomm) Capacity is increased with a dense deployment of self-backhauled small cells (“3rd layer of small cell”)
146 * 3GPP, RWS-120007, Qualcomm, “3GPP RAN Rel-12 & Beyond,” June 2012.
73 2013-09-05
Heterogeneous Networks : Current works Handover between macro cell and femto cell HeNB compared to eNB Small coverage Low tx power Random deployment by users Indoor deployment
eNB eNB • Symmetric signal power • Lower interference • Same tx power of neighbor eNBs
eNBHeNB • Asymmetric signal power • Higher interference from eNB to HeNB • Large PL due to wall-loss • Higher interference -> worse HeNB RSRQ
• Require different event for HO decision Relative value Absolute value 147
Heterogeneous Networks : Current works Femto cell Handover Inbound handover Femto-to-femto handover Outbound handover
148
74 2013-09-05
Femto cell Inbound HO (아주대)
Femto cell inbound handover: Macro -> Femto cell HO triggering condition Signal power level: macro eNB >> femto HeNB UE satisfies A4 condition during TTT -> HO request to S-eNB -> HO execution
HO delay TTT
• H/O completion hyst threshold Measured value • Satisfaction A4 event • HO execution 149
Femto cell Inbound HO : SI Measurement (아주대) System Information Essential parameters by which the network can control the cell selection process In the macro HO procedure, the UE gets the SI of target cell from serving eNB But, in the inbound HO from macro cell to CSG cell S-GW don’t manage the cell information of femto cells UE have to measure SI of target cells
. C.-H. Lee and J.-H. Kim, “System Information Acquisition Schemes for Fast Scanning of Femtocells in 3GPP LTE 150 Networks,” IEEE Communications Letters, vol. 17, no. 1, pp. 131–134, Jan. 2013.
75 2013-09-05
Femto cell Inbound HO : SI Measurement (아주대) Serial methods UE measures MIB & SIB1 packets cell-by-cell Scheduled/Autonomous Parallel method UE measures all MIB packets UE measures SIB1 packets in order of the expected arrival time. Autonomous
. C.-H. Lee and J.-H. Kim, “System Information Acquisition Schemes for Fast Scanning of Femtocells in 3GPP LTE 151 Networks,” IEEE Communications Letters, vol. 17, no. 1, pp. 131–134, Jan. 2013.
Femto cell Inbound HO : SI Measurement (아주대) Simulation environment • Assumption OPNET – UE find 6 femtocells during every neighbor search
• Simulation parameters
. C.-H. Lee and J.-H. Kim, “System Information Acquisition Schemes for Fast Scanning of Femtocells in 3GPP LTE 152 Networks,” IEEE Communications Letters, vol. 17, no. 1, pp. 131–134, Jan. 2013.
76 2013-09-05
Femto cell Inbound HO : SI Measurement (아주대)
Measurement Delay Scheduled > Autonomous methods Serial > Parallel methods However, autonomous methods have possibility of packet drop, because the serving cell cannot know whether the UE is disconnected or not 153
Heterogeneous Network : Market Status Number of Number companies
154 * Informa Telecoms & Media, “Small cell Market Status,” 2013. 2.
77 2013-09-05
Heterogeneous Network : Market Status Selection of pricing models for Femtocell deployment segmentation femtocell services according to target group Pricing Number of Market Deployment examples Target model deployme Examples Group nts Add-ons for MOLD TELECOM, unlimited Vodafone UK, AT&T, Sprint, YES OPTUS Consumer 26 calling Cosmote
Softbank, T-Mobile UK, Network Free Enterprise 6 Vodafone(Greece), SFR Norway, Orange France Consumer Consumer Vodafone NZ, Verizon Low upfront Vodafone(UK, Italy, & 8 Wireless, Sprint fee Hungary), Verizon Enterprise
Sprint, Movistar, NTT Vodafone Qatar, SK Monthly fee Public 5 DoCoMo Telecom, TOT Thailand High upfront Softbank (using Enterprise All operators Rural 1 fee satellite backhaul) 155 * Informa Telecoms & Media, “Small cell Market Status,” 2013. 2.
Heterogeneous Network : Market Status Launch Company Country Offering Example Pricing Capabilities date Consumer and Enterprise: US$4.99 per month Up to 6 users 2007 .9 Airave (US$10 for unlimited Sprint US calling, US$20 for family plans) Consumer and Enterprise: US$249.99 Up to 3 users 2009.1 Verizon US Network Extender Consumer: Sure Various options£50 Up to 4 users 2009. 7 Vodafone UK Signal(UMTS/HSPA) upfrontFree 2010. 1 for >£45 contracts Consumer: 3G MicroCell US$159 Up to 4 3G 2009.9 at&t US users Consumer: Home €199 upfront Up to 4 3G 2009.11 SFR France 3G(UMTS/HSPA) users NTT Consumer: My US$10 per month Up to 4 3G 2009.11 Japan Docomo Area(UMTS/HSPA) users
156 * Informa Telecoms & Media, “Small cell Market Status,” 2012. 6.
78 2013-09-05
Heterogeneous Network : Market Status Launch Company Country Offering Example Pricing Capabilities date Consumer: Femtocell Up to 4 3G Softbank Japan Free of charge 2010. 6 service(WCDMA) users Free of charge (in Consumer: au Femtocell Up to 4 3G KDDI Japan coverage 2010. 6 (CDMA2000 1xEV-DO) users deadspots) South Public: Femtocells for Deployed in public Up to 4 3G SKtelecom 2010.12 Korea data offload areas users Consumer: Consumer/Ent Consumer and Enteprise: Vodafone Italy €240Enterprise: erprise: Up to 2011. 5 Booster PrivatiBooster €780 4/8 users Upfront fee: Enterprise: Couverture Site €1,400Monthly fee: Orange France Up to 4 users 2011. 5 Confort €70Multi-FAP plans available
157 * Informa Telecoms & Media, “Small cell Market Status,” 2012. 6.
Heterogeneous Network : Commercial Products in Korea Service providers deploy small cells
SKT 2010.12: 3G femto cell 2011. 5: 3G femto cell + WiFi AP 2012. 5: LTE femto cell + WiFi AP Power over Ethernet 2013. 4: Femto Remote Solution Reduce Femto cell interference KT 3G femto cell VDSL No HO supported 2012. 6: LTE femto cell 100Mbps optical fiber 2013. 6: Home Femto cell LGU+ 2013.7: LTE femto cell Use different carrier frequency with macro cell
158
79 2013-09-05
LTE-Advanced Features Heterogeneous Networks Carrier Aggregation Offloading
159
Carrier Aggregation Overview
What is the Carrier Aggregation (CA)? Two or more component carriers (CCs) are aggregated UE may simultaneously receive or transmit one ore multiple CCs corresponding to multiple serving cells
Motivation BW aggregation is required for IMT-Advanced Peak data rate: 1 Gbps in the downlink, 500 Mbps in the uplink BW requirement set by ITU-R: up to 100 MHz
160
80 2013-09-05
Carrier Aggregation Modes
Contiguous carrier Carrier Aggregation aggregation Possibly only one FFT module and one radio frontend Band A CC1 CC2 CC3
Band A CC1 Band B CC2 FFT: Fast Fourier transform
Carrier Aggregation in LTE
Carrier aggregation in previous 3GPP 3GPP2 1xEV-DO Rev. B (multiple 1.25 MHz carriers) 3GPP HSPA (up to 4 DL / 2UL carriers, of 5 MHz each) Contiguous, same band, same BW
Carrier aggregation in LTE Contiguous and non-contiguous Various carrier BW (1.4, 3, 5, 10, 15, 20 MHz) Various frequency band (SKT: 800MHz, 1.8GHz, KT: 900MHz, 1.8MHz, LG U+: 800MHz, 2.1GHz) Control channel design for UL/DL Backward compatibility Reuse of Rel. 8/9 RF designs and implementation at the eNB and UE
162
81 2013-09-05
Serving Cells in CA
Primary serving cell (PCell) The RRC connection is handled by the PCell, Secondary serving cell (SCell) SCell information is obtained via dedicated signaling on PCell SCells provide additional radio resources
Primary Serving Cell(PSC), Secondary Serving Cell(SSC), Primary Component Carrier (PCC), Secondary Component Carrier (SCC), RRC connection and data User data only
J.Wannstrom, “ Carrier Aggregation explained”, http://www.3gpp.org/Carrier-Aggregation-explained , May, 2012 163
Protocol Architecture for CA (1/3)
Rel. 10 UE can be configured with multiple serving cells When in RRC_CONNECTED state Each serving cell corresponds to a different DL CC
Radio Bearers
ROHC ... ROHC ROHC ... ROHC PDCP ... Security ... Security Security ... Security
Segm. Segm. Segm. Segm. Segm. Segm...... RLC ARQ etc ARQ etc ARQ etc ARQ etc CCCH BCCH PCCH MCCH MTCH Logical Channels
Unicast Scheduling / Priority Handling MBMS Scheduling
Multiplexing UE1 ... Multiplexing UEn Multiplexing MAC
HARQ ... HARQ HARQ ... HARQ
Transport Channels
DL-SCH DL-SCH DL-SCH DL-SCH BCHPCH MCH on CC1 on CCx on CC1 on CCy
164 * 3GPP TS 36.300 V11.2.0 “E-UTRA and E-UTRAN; Overall description”, June, 2012
82 2013-09-05
Protocol Architecture for CA (2/3)
Control plane UE only has one RRC connection with the network UE (re-)establishes RRC connection on a single cell RRC signaling is used to add, remove, or reconfigure additional serving cells UE is assigned a single C-RNTI (Cell Radio Network Temporary Identifier) Uniquely identify the RRC connection of the UE For scheduling purposes on the PDCCH transmitted on any of the activated DL CCs MAC is used for dynamic management of serving cells to be used among the configured set of serving cells
165
Protocol Architecture for CA (3/3)
Data plane CA is only exposed to the MAC sublayer MAC performs unicast scheduling and priority handling across all active serving cells of a UE in a way that is transparent to upper layers Each transport block and its potential HARQ retransmission are mapped to a single serving cell Independent HARQ process for each DL or UL CC
166
83 2013-09-05
CA scheduling
Normal scheduling Scheduling grant and resource on same carrier Cross-carrier scheduling Scheduling grant and resource NOT on the same carrier Schedule resources on SCC without PDCCH The CIF (Carrier Indicator Field) on PDCCH (represented by the red area) indicates on which carrier the scheduled resource is located.
PCC SCC PCC SCC PCC SCC PCC SCC
167
Status of Commercial Services for CA (1/6)
Bandwidth allocation for KT, SKT, LGU Uplink Downlink
168
84 2013-09-05
Status of Commercial Services for CA (2/6)
Hot Issues about Bandwidth allocation Primary Primary Secondary
SKT LGU 경매 경매 KT SKT LGU -LTE -LTE -LTE -LTE -LTE -LTE -CDMA -20Mhz -20Mhz -35Mhz -15Mhz -20Mhz -20Mhz -20Mhz Frequency 800MHz~ 1.8GHz~
Secondary
LGU SKT KT -LTE -WCDMA -WCDMA -20Mhz -60Mhz -40Mhz 2.1GHz~ Frequency
경매 경매 -LTE -LTE -40Mhz -40Mhz 2.6GHz~ Frequency 169
Status of Commercial Services for CA (3/6)
Commercial services for Multi-carrier(MC) and CA * Multi-carrier technology Select one of frequency bands to optimize the load balancing when LTE data traffic increases SKT LTE-A network deployment for 850Mhz & 1.8GHz frequency band • Deployment completion in 84 major cities, Korea (2013. 07) • Starting MC service (2012.07) • Starting CA service (2013.06) LG U+ LTE-A network deployment for 800Mhz & 2.1GHz frequency bands • Deployment completion in Seoul and major cities, Korea (3Q of 2013) • Deployment completion in rest cities, Korea (4Q of 2013) • Starting MC service (2013.05) • Starting CA service (2013.07)
. SKT hompage, “SK텔레콤, 30일 84개시 중심가로 ‘LTE-A’ 확대”, http://www.sktelecom.com, July, 2013. 170 . LGU+ homepage, “LG유플러스, 세계 최초 ‘100% LTE’ 상용화”, www.uplus.co.kr, July, 2013.
85 2013-09-05
Status of Commercial Services for CA (4/6)
SKT: “아무나 가질 수 없는 속도 LTE-A” 세계최초 Carrier Aggregation 상용화 서비스 한시적 (7월) 데이터 2배 제공
171
Status of Commercial Services for CA (5/6)
LGU+: “100% LTE 가 아니면 요금을 안받겠습니다.” 세계최초 100%LTE 상용화 (Voice 와 data를 동시서비스) WCDMA(3G)망 없음
172
86 2013-09-05
Status of Commercial Services for CA (6/6)
KT: “난 데이터가 2배 라구요!” Multi carrier/Carrier Aggregation 서비스 안함 한시적으로 데이터량 2배 제공 (2013. 7~10월)
173
LTE-Advanced Features Heterogeneous Networks Carrier Aggregation CoMP
174
87 2013-09-05
CoMP
CoMP (Coordinated MultiPoint transmission and reception) The coordination of transmissions from multiple cells (especially at the cell edge Basic CoMP schemes can be realized in Release 8 between the cells controlled by a given eNodeB The evolution of LTE-Advanced for Release 11 or beyond
표준 기술 동향 및 전망 * 윤영우, “LTE-Advanced (REL-10 REL-11 )”, 한국통신학회지(정보와통신), 2011.5 175 * S.Seia, I. Toufik, M. Baker, “LTE The UMTS Long Term Evolution –From Theory to Practice, Second Edition”.
CoMP
CoMP schemes Coordinated scheduling / beamforming Share the channel and scheduling information between the coordin ated cells to reduce interference in a UE Scheduling UE / beamforming Coherent joint transmission Multipoint transmission to single UE Dynamic switching (Fast cell selection) Dynamically handover to the selected cell
* S.Seia, I. Toufik, M. Baker, “LTE The UMTS Long Term Evolution –From Theory to Practice, Second Edition”. * NTT DOCOMO, ‘R1-090314: Investigation on Coordinated Multipoint Transmission Schemes in LTE-Advanced 176 Downlink’, www.3gpp.org, 3GPP TSG RAN WG1, meeting 55bis, Ljubljana, Slovenia, January 2009.
88 2013-09-05
CoMP
CoMP schemes
Coherent Fast cell selection (FCS)
* S.Seia, I. Toufik, M. Baker, “LTE The UMTS Long Term Evolution –From Theory to Practice, Second Edition”. * NTT DOCOMO, ‘R1-090314: Investigation on Coordinated Multipoint Transmission Schemes in LTE-Advanced 177 Downlink’, www.3gpp.org, 3GPP TSG RAN WG1, meeting 55bis, Ljubljana, Slovenia, January 2009.
CoMP Related Example : BS Cooperation BS cooperation 성능 분석 BS cooperation 네트워크 관점의 성능 평가 시뮬레이터 구현 사항 기지국 구성 1 서빙기지국, 2 협력기지국, 16 dummy 기지국 기지국당단말수 10개단말 기지국 반경 1 Km Pathloss model 130.19+37.6log10(R) (R in km) Shadowing Model Log-normal dist 채널 모델 (mean: 0, variation: 8 dB) Thermal Noise Den -174dBm/Hz sity 신호 결합 및 측정 Soft combining ,
Bandwidth 10Mhz (1024 FFT) Frame 5 msec (TDD) MCS level QPSK ½, 16QAM ½, 64QAM½ Cell load 90% Triggering 셀내 위치기반 동작 / SINR 신호기반 동작 자원할당 방법 협력기지국간 동일 Band 할당
*J. S. Kim, K. C. Go, S. K. Oh and J. H. Kim, "Performance Evaluation of BS Cooperative Communication in Networks-Wise," in Proc. ICUIMC 2013, Kota Kinabalu, Malaysia, Jan. 17 - Jan. 19, 2013. 178
89 2013-09-05
CoMP Related Example : BS Cooperation Messages for BS cooperation BS cooperation 동작을 위한 MAC 메시지 플로우 설계 IEEE 802.16e system 기반 유/무선 Control message 설계 Message overhead (무선) Cooperative Service Request (208 bits) • Cooperative Service request info • CQI info • Location info Cooperative Service Response (381 bits) • Cooperative service response info • Resource allocation info •Synch info
179
CoMP Related Example : BS Cooperation 셀 경계 사용자 비율에 따른 성능*
BS cooperation 사용에 따른 셀 경계 사용자의 Throughput 향상 BS cooperation 사용자 증가 시 자원 overhead증가로 전체 셀 Throughput 감소
NO-CO: No coopration, CO-DM: Dynamic point Muting cooperation, CO-JT: Joint Transmission Cooperation
*J. S. Kim, K. C. Go, S. K. Oh and J. H. Kim, "Performance Evaluation of BS Cooperative Communication in 180 Networks-Wise," in Proc. ICUIMC 2013, Kota Kinabalu, Malaysia, Jan. 17 - Jan. 19, 2013.
90 2013-09-05
Release 12 Issues Offloading WLAN Network Selection Device-to-Device Communications Machine Type Communication (MTC)
181
3GPP Traffic Offloading
Rel-8 Rel-9 Rel-10 Rel-11 Rel-12
• LIMONET (LIPA Mobility • LIPA (local IP access) Femto • H(e)NB and SIPTO at the local • SIPTO (selected IP traffic offload) network)
• WLAN_NS(WLAN network • MAPCON (multi access PDN selection for 3GPP • SaMOG (S2a mobility connectivity) terminals) based on GTP and • IFOM (IP flow mobility) • FS_SAMOG • Seamless WLAN access) Wi-Fi • NSWO (non-seamless WLAN • FS_NBIFOM(network- Handover • LOBSTER (location- offload) based IP flow mobility) based selection of • SMOG (S2a mobility based on • FS_WORM(optimized gateway for WLAN) GTP) offloading to WLAN in 3GPP RAT mobility)
• ANDSF • OPIIS (operator policies (access • DIDA (data identification for IP interface selection) Policy network • ANDSF–ISRP (inter-system routi in ANDFS) • P4C (PCC control for aspects discovery ng policy) • BBAI (broadband forum supporting fixed and access interworking) broadband access selection) networks)
182 • 김현숙, “3GPP Traffic Offload”, FMC 포럼 컨버젼스 기술 및 표준 워크샵, 2012. 12. 12.
91 2013-09-05
Benefits of Traffic Offloading
Mobile Operators Devices can connect directly to servers without going through core networks Mobile Operators can offer CDN(contents delivery network) services End-users RTTs can be expected to reduce and consequently throughput increases from the end-users’ viewpoint Service Provider Reduced RTTs and increased throughput can be expected by using storage in backhaul networks and providers can offer “fact access” to end-users as premium services to obtain extra revenues from the service providers’ view point Service providers can offer very rich and geographical oriented services by using storage in eNBs
183 • NEC corporation, “Mobile Traffic Offload: NEC’s Cloud Centric Approach to Future Mobile Networks,” 2013. 04.
Data Offloading
Different data offloading techniques Path 1: WLAN solutions allow data offload directly to the Internet without utilizing service provider’s resources Path 2 : Femtocells or H(e)NBs permit data offload via a Local Gateway(L-GW) Path 3 : maintaining home/enterprise related traffic local, via LIPA Path 4 : Data offload may be positioned at or above particular eNBs for eUTRAN Path 5 : Radio Network Controller (RNC) for UTRAN
• Konstantinos Samdanis, Tarik Taleb, Stefan Schmid, “Traffic Offload Enhancements for eUTRAN,” IEEE 184 COMMUNICATIONS SURVEYS & TUTORIAL, 2012.
92 2013-09-05
LIPA & SIPTO
Residential / Enterprise network LIPA L-GW Backhaul H(e)NB Mobile Operator H(e)NB -GW Core Network
UE Key issues Legal interception QoS Single/multiple PDN support Deployed behind NAT Operator control for SIPTO
• 3GPP TR 23.829 V10.0.1, “3GPP technical specification group services and system aspects; local IP access and 185 selected IP traffic offload (Release 10),” 2011. 10.
LIPA & SIPTO
Solution 1 – variant 1
EPC Home network IP backhaul S5 SGW PGW L-GW Home SeGW S5 router/ S1-U HeNB S11 NAT S1-mme MME
UE
Local PDN GW (L-GW) function is collocated with the HeNB Paging of Idle mode UEs is triggered by sending the first downlink user packet or a “dummy” packet on S5 All other downlink user packets are buffered in the L-GW
SeGW: security gateway, SGW: serving gateway, PGW: PDN gateway, MME: mobility management entity
• 3GPP TR 23.829 V10.0.1, “3GPP technical specification group services and system aspects; local IP access and 186 selected IP traffic offload (Release 10),” 2011. 10.
93 2013-09-05
LIPA & SIPTO
Solution 1 – variant 2 LIPA Traffic CN RAN
L-S11 MME L-GW S1-MME S11
HeNB S-GW P-GW S1-U S5 UE CN Traffic
L-GW can be either collocated with the HeNB or as a standalone node L-S11 interface between the L-GW and the MME is used to manage the session for LIPA traffic L-GW needs to be selected close to the HeNB Open issues Whether Mobility is supported/required for LIPA Whether the standalone L-GW architecture is supported for LIPA, and if it is, how • 3GPP TR 23.829 V10.0.1, “3GPP technical specification group services and system aspects; local IP access and 187 selected IP traffic offload (Release 10),” 2011. 10.
LIPA & SIPTO
Solution 2 – variant 1
Internet OPM
EPC Home/Enterprise IP Backhaul Network MME
S1’-c S11 GW / NAT SeGW HeNB SGW S5 PGW S1-u
NAT Function Block Routing Function Block
UE Offload Processing Module (OPM)
UEs are only required to activate one PDN connection for LIPA The OPM has the ability to drag/insert the LIPA traffic from/into PDN connection per operator policies (dst addr, Port #, etc.)
• 3GPP TR 23.829 V10.0.1, “3GPP technical specification group services and system aspects; local IP access and 188 selected IP traffic offload (Release 10),” 2011. 10.
94 2013-09-05
LIPA & SIPTO
Solution 3 GGSN allocation to offload point LIPA and SIPTO are enabled by the SGSN selecting a GGSN that provides enhanced (e.g. shorter) traffic routeing capabilities located within the RAN The RAN providing the SGSN with the IP address(es) of one or more GGSNs that the RAN believes offers good traffic routeing capabilities The SGSN using the information from the RAN and HSS to potentially override the normal GGSN selection algorithm The SGSN using the permitted CSG/APN information and information supplied by the RAN to cause the release of a PDP context, if required by the service continuity restrictions, when the mobile leaves the CSG
• 3GPP TR 23.829 V10.0.1, “3GPP technical specification group services and system aspects; local IP access and 189 selected IP traffic offload (Release 10),” 2011. 10.
LIPA & SIPTO
Solution 4 Selected IP Traffic Offload at Iu-PS
CG LIG
Ga
SGSN GGSN UE NB RNC TOF
Uu Iub Iu Iu Gn
Iu Gi
HNB UE HNB VAS GW Gi Uu Iuh Internet The traffic is offloaded after the RNC and before the SGSN in the Traffic Offload Function(TOF) Using Deep Packet Inspection(DPI) in the TOF a great level of granularity can be achieved TOF can be a separate entity, or collocated with RNC/HNB GW
• 3GPP TR 23.829 V10.0.1, “3GPP technical specification group services and system aspects; local IP access and 190 selected IP traffic offload (Release 10),” 2011. 10.
95 2013-09-05
LIPA & SIPTO
Solution 5 SIPTO Traffic
CN L-PGW MME RAN S5 S11
S1-U S5 eNB S-GW P-GW
UE CN Traffic
Selected IP Traffic Offload solution based on local PDN GW selection The L-PGW is not co-located with the H(e)NB but is close by in the network The GW selection mechanism in the MME/SGSN takes into account the location of the user for the PDN connection/PDP context activation, and selects a GW that is geographically/topologically close
• 3GPP TR 23.829 V10.0.1, “3GPP technical specification group services and system aspects; local IP access and 191 selected IP traffic offload (Release 10),” 2011. 10.
LIPA & SIPTO
Solution 6
GERAN/ … added functionality UTRAN SGSN HSS … added interface S3 S1 - MME S6a MME PCRF S11 S12 Gx Rx S4 S10 LTE-Uu Serving S5 PDN SGi Operator's IP (H ome ) eNB UE Gateway Gateway Services S1-U L- GW Local Extension Network or SGi Tunnels Internet L- GW Gi
(H ome ) NB UE GGSN Uu GERAN/ SGSN Gn UTRAN Iu
L-GW is collocated with HeNB “L-GW extension tunnel” between the L-GW and the PDN GW
• 3GPP TR 23.829 V10.0.1, “3GPP technical specification group services and system aspects; local IP access and 192 selected IP traffic offload (Release 10),” 2011. 10.
96 2013-09-05
LIPA & SIPTO
Conclusion on the LIPA architecture Solution 1 – variant 1 is selected as the basis for LIPA to be included in normative specifications Supporting both a collocated and stand-alone L-GW as well as mobility (w/o mobility for Rel-10) Impacts to L-GW configurations LIPA_enabled flag (per APN and per CSG) in the user's subscription data stored in the HSS/HLR and transferred to the MME/SGSN (E-)RAB setup messages: addition of new correlation identifier (user plane L-GW TEID) Adding the transmission of the IP address of the L-GW in UE- associated signalling in the uplink, or, alternatively, DNS-based L-GW selection Possible Multicast support in the L-GW
• 3GPP TR 23.829 V10.0.1, “3GPP technical specification group services and system aspects; local IP access and 193 selected IP traffic offload (Release 10),” 2011. 10.
Release 12 Issues Offloading WLAN Network Selection Device-to-Device Communications Machine Type Communication (MTC)
194
97 2013-09-05
3GPP/Non-3GPP access network selection
Access Network Selection for Offloading*
HSS SWx Procedure Get target system information by S6a PCRF Rx ANDSF Gxc Gx UE connects to target system Operator's IP SGi Services (e.g. Authentication of UE S5 3GPP Serving PDN IMS, PSS, etc.) Access Gateway Gateway Receive QoS information through PCRF Access to same PGW, and do binding S6b Gxb update by PMIP SWm 3GPP AAA ePDG Server Features HPLMN SWn PMIP: Anchor point PGW
Non-3GPP Gxa UE: LTE/Non-3GPP dual radio terminal Networks Trusted Non- Untrusted 3GPP IP Non-3GPP IP Get address of PGW by saving address SWa Access Access STa information to HSS
S2c S2c UE S2c
• PMIP: Proxy Mobile IP • PCRF: Policy and Charging Rules Function
* 3GPP TS 23.402 V12.1.0, “Architecture enhancements for non-3GPP accesses”, June 2013. 195
ANDSF*
Definition A framework for specifying and delivering access network selection policy to UE
Purpose To assist UE to discover non-3GPP access networks
Function Provide the information to UE ISMP: Network selection rules for a UE with no more than one active access network connection ISRP: Network selection rules for a UE with more than one active access network connection Discovery information: a list of networks that may be available in the vicinity of the UE UE location: geographical coordinates, a cellular cell or area, a WLAN location (SSID, BSSID) UE profile
• ANDSF: Access Network Discovery and Selection Function • ISMP: Inter-System Mobility Policy • ISRP: Inter-System Routing Policy
* 3GPP TS 24.312 V12.1.0, “Access Network Discovery and Selection Function (ANDSF) Management Object 196 (MO)”, June 2013.
98 2013-09-05
Key issues related to WLAN network selection* Key issue 1 Support WLAN access through roaming agreements Current ANDSF support WLAN network selection policies based on SSID only • Providing SSID preferences to UEs
* 3GPP TS 23.865 V1.0.0, “WLAN network selection for 3GPP terminals”, June 2013. 197
Key issues related to WLAN network selection Solution for key issue 1 ANDSF policies with extended selection preferences Use Realms and/or OUIs instead of using SSID • Realm/OUI identify and prioritize the discovered WLAN access networks » Ex) WLANs that interwork with Realm=PartnerX.com have the highest access priority
• OUI: Organizational Unique Identifier
198
99 2013-09-05
Key issues related to WLAN network selection Key issue 2 Interaction between WLAN network selection and network- provided policies for WLAN selection ANDSF rules are evaluated only after WLAN network selection is performed • WLAN network selection priority list in the UE • ANDSF rules cannot trigger the UE to select another WLAN access network
Solution for key issue 2 WLAN selection based on ANDSF rules Use enhanced ISMP/ISRP rules • SSID preferences • Additional preferences » Realms (preferred service providers), OUIs, available backhaul bandwidth, connectivity capability, etc.
199
Key issues related to WLAN network selection Key issue 3 Delivery of consistent information for WLAN network selection Conflicting between the information from different sources or different management objects • WFA Hotspot 2.0 specifications » WFA Hotspot 2.0: Provide seamless handoff without additional authentication • Relevant components » ANDSF management object and USIM in 3GPP
Key issue 4 Use WLAN load information for network selection ANDSF does not provide load information or congestion indication of WLAN networks: BSS load and backhaul parameters The policies for WLAN network selection may be enhanced to take these parameters into account
200
100 2013-09-05
Key issues related to WLAN network selection Key issue 5 Use WLAN access network type and venue information for network selection Access network type: private, public, free, personal, emergency, etc. Venue information: venue type and name • Help to identify the venue where WLAN network may be deployed (e.g. school, hotel, etc.)
Key issue 6 Use connection capability during WLAN network selection Connection capability • To provide information on the connection status within the WLAN network ANDSF does not take into account the connection capability of the WLAN networks • WLAN network may block the IP flows of the UE
201
Key issues related to WLAN network selection Solution for key issue 3, 4, 5, and 6 Provide both ANDSF MO(with ISMP, ISRP etc.) and HS2.0 MO to the UE Example of HS2.0 MO: the load of the AP
ANDSF MO enhanced with policies related to information elements available in HS2.0 Example: ISRP and ISMP as extensions to the prioritized access descriptions
• HS: Hotspot • MO: Management Object 202
101 2013-09-05
Release 12 Issues Offloading WLAN Network Selection Device-to-Device Communications Machine Type Communication (MTC)
203
D2D Communications
What is D2D communication ? Refer to the technologies that enable devices to communicate directly without an infrastructure of access points or base stations, and the involvement of wireless operators. Proximate discovery • There is also a broad range of other potential applications that is contributing to industry enthusiasm and activity.
* 3GPP TR 22.803 V12.2.0, “Feasibility study for Proximity Services (ProSe) (Release 12),” 2013.06 * L. Lei, Z. Zhangdui, L. Chuang, and S. Xuemin, "Operator controlled device-to-device communications in LTE-advanced networks," IEEE Wireless Communications, vol. 19, pp. 96-104, 2012. 204
102 2013-09-05
D2D vs. MTC
D2D MTC
Device Type • Cell phones or other devices in • Machine-to-Machine human-to-human communications communications without the involvement of human activities
Communication • Directly communication between • Communication via infrastructure Type devices of LTE networks Related Spec. • 3GPP TR 22.803 • 3GPP TS 22.368 • 3GPP TR 23.887 Application • Social matching • Metering • Push advertising • Remote Maintenance/Control • Multiplayer gaming • Health care • Local voice service • Tracking & Tracing • Contents sharing • Security system
* 3GPP TR 22.803 V12.2.0, “Feasibility study for Proximity Services (ProSe) (Release 12),” 2013.06 * 3GPP TS 22.368 V12.2.0, “Service requirements for Machine-Type Communications (MTC);Stage 1(Release 12),” 2013. 03 * 3GPP TR 23.887 V1.0.0, “Machine-Type and other Mobile Data Applications Communications Enhancements (Release 12),” 2013. 06.205
Use Case and Business Model
Local Voice Service D2D communications can be used to offload local voice traffic when two geographically proximate users want to talk on the phone.
* L. Lei, Z. Zhangdui, L. Chuang, and S. Xuemin, "Operator controlled device-to-device communications in LTE-advanced networks," IEEE Wireless Communications, vol. 19, pp. 96-104, 2012. 206
103 2013-09-05
Use case and business model
Local Data Service D2D Communications can be used to provide local data service when two geographically proximate users or devices want to exchange data
* L. Lei, Z. Zhangdui, L. Chuang, and S. Xuemin, "Operator controlled device-to-device communications in LTE-advanced networks," IEEE Wireless Communications, vol. 19, pp. 96-104, 2012. 207
Use case and business model
Data Relay D2D Communications can be used to relay data for devices that are not “directly cellular”.
* L. Lei, Z. Zhangdui, L. Chuang, and S. Xuemin, "Operator controlled device-to-device communications in LTE-advanced networks," IEEE Wireless Communications, vol. 19, pp. 96-104, 2012. 208
104 2013-09-05
Introduction of Proximity Service
Proximity Services (ProSe) Proximity services that identify mobiles in physical proximity and enable optimized communications between them
ProSe Discovery A process that identifies that a UE is in proximity of another, using E-UTRA Open ProSe Discovery • is ProSe Discovery without explicit permission from the UE being discovered Restricted ProSe Discovery • is ProSe Discovery that only takes place with explicit permission from the UE being discovered.
E-UTRA: Evolved Universal Terrestrial Radio Access
209 . 3GPP TR 22.803 V12.2.0 “Feasibility study for Proximity Services(ProSe)”, June, 2013
Introduction of Proximity Service
ProSe Communication A communication between two UEs in proximity by means of a E-UTRAN communication path established between the UEs. The communication path could for example be established directly between the UEs or routed via local end(s) ProSe Group Communication • a one-to-many ProSe Communication, between two or more UEs in proximity, by means of a common communication path established between the UEs. ProSe Broadcast Communication • a one-to-all ProSe Communication, between all authorized UEs in proximity, by means of a common communication path established between the UEs.
E-UTRAN: Evolved Universal Terrestrial Radio Access Network
210 . 3GPP TR 22.803 V12.2.0 “Feasibility study for Proximity Services(ProSe)”, June, 2013
105 2013-09-05
ProSe Communication
Data paths for ProSe communication path ProSe E-UTRA Communication path could be established Directly path between the ProSe-enabled UEs using E-UTRA Locally routed path via local eNB(s) ProSe-assisted WLAN direct communication path is established directly between the ProSe-enabled UEs using WLAN
Direct mode Locally-routed 211 E-UTRA: Evolved Universal Terrestrial Radio Access
ProSe Communication
Control paths for ProSe communication path General Case The system can decide to perform ProSe Communication using control information exchanged between the UE, eNB, EPC by the solid arrows The UEs can in addition exchange control signalling via the ProSe Communication path as shown by dashed arrow
UEs served by the same eNB UEs served by the different eNBs 212
106 2013-09-05
ProSe Communication
Disaster Case (Public Safety UE) The Public Safety UEs can rely on pre-configured radio resources to establish and maintain the ProSe Communication Public safety Radio resource Management Function, which can reside in a Public Safety UE, can manage the allocation of radio resources for Public Safety ProSe Communication as shown with the dashed arrows
With resource controller UE
With pre-configured radio resources
UEs without network support 213
General Use Case
Restricted ProSe Discovery use case This use case describes a basic scenario for ProSe Discovery that can be used for any application A social networking application is used as an example
Relationship(explicit permission)
214
107 2013-09-05
General Use Case
Open ProSe Discovery use case This use case describes a case in which UEs discover other UEs without permission by the discoverable UEs
215
General Use Case
Discovery use case with roaming subscribers This use case describes discovery between UEs in different PLMNs under roaming condition
216
108 2013-09-05
Public Safety Use Case
ProSe discovery within network coverage This use case describes the scenario where a given UE discovers one or more other UEs while in LTE coverage, with ProSe Discovery always enabled ProSe discovery out of network coverage This use case describes the scenario where a given UE discovers one or more other UEs while out of E-UTRAN coverage, with ProSe Discovery always enabled
Within network coverage Out of network coverage 217
Public Safety Use Case
Can discover but not discoverable This use case describes the scenario where a given UE is able to discover other UEs, but is not discoverable by other UEs
I don’t want to be discovered
218
109 2013-09-05
Public Safety Use Case
ProSe relay This use case describes the scenario where a given UE acts as a communication relay for one or more UEs
Without relay With relay
219
Public Safety Use Case
ProSe group This use case describes the scenario where a user wants to communicate the same information concurrently to two or more users using ProSe Group Communications
220
110 2013-09-05
Public Safety Use Case
ProSe broadcast This use case describes the scenario where a given UE initiates a ProSe Broadcast Communication transmission to all UEs within transmission range
221
Reference model
Architecture reference model
New reference points S141 : Reference point between UE and H-DPF or between UE and a DPF in a local PLMN where the Basic Concept UE is authorised by the H-DPF to perform direct 1. UE obtains configuration for direct services from services. It enables PLMN-specific direct services Direct Services Provisioning Function (DPF) authorization in a secure way S142 : Reference point between DPF in local 2. Direct Services Provisioning Function (DPF) PLMN and H-DPF. It enables PLMN-specific direct exists in every PLMN services authorization 3. UE obtains configuration from Direct Services U2 : Reference point used for all the control and Provisioning Functions (DPFs) in PLMNs is user plane information exchange needed in order authorised to perform direct discovery to perform direct discovery between two UEs 222 . S2-131505 “Solution for direct discovery and communication”, April, 2013
111 2013-09-05
Reference model
Signaling flow for UE provisioning from DPF
Authorisation for direct discovery 1. Is the UE allowed to announce in this PLMN? 2. Is the UE allowed to “monitor” in this PLMN?
PLMN: Public Land Mobile Network MCC: Mobile Country Code FQDN: Fully Qualified Domain Name 223
Reference model
Two roles for the UE in ProSe Discovery Announcing UE : The UE announces certain information that could be used from UEs in proximity that have permission to discover Monitoring UE : The UE that receives certain information that is interested in from other UEs in proximity
224
112 2013-09-05
Public Safety Network
What is Public Safety Network? Public safety networks provide communications for services like police, fire and ambulance
Before: P25 and TETRA Poor interoperability of PTT(Push To Talk) Narrowband System Narrowband systems can’t handle real-time video, detailed maps and blueprints, high-resolution, photographs and other files.
LTE system can provide greater interoperability and the broadband capabilities to the public safety network P25: Project 25 TETRA: TErrestrial Trunked Radio *T. Doumi, M. F. Dolan, S. Tatesh, A. Casati, G. Tsirtsis, K. Anchan, and D. Flore, "LTE for public safety 225 networks," IEEE Communications Magazine, vol. 51, pp. 106-112, 2013.
Why LTE ?
Greater interoperability and enhanced interagency cooperation: Sophisticated priority access mechanisms authorize and prioritize communication, so mission-critical data gets top priority. Standardized protocols and interfaces: Roaming capabilities are built in. Unprecedented broadband capabilities: LTE provides high capacity, allowing a wide variety of applications that have rich, multimedia content. It provides low latency, enabling real-time services (VoIP, video). Cost effective: LTE’s simplified architecture lowers operating costs. It leverages a rich, open ecosystem from commercial networks. Highly reliable and secure: LTE offers advanced quality of service. It supports encryption/ciphering to enable secure communications.
*Government Technology white paper, "A How-To Guide for LTE in Public Safety," 2010. 226
113 2013-09-05
Network Model
*Government Technology white paper, "A How-To Guide for LTE in Public Safety," 2010. 227
Feature & Requirements of Public Safety Networks
Feature Requirements Group call • A group call involves the communication of speech to all members of the group • Data messaging can also be sent in parallel to speech QoS • A segment of emergency group call speech will need higher priority to guarantee that it is not delayed by regular daily activities. Robustness • It demands that alternative paths be available in the event of congestion and resource outages Direct Mode • When part of a public safety network fails, the remainder of the network must continue to provide services to the greatest extent possible • Direct mode is the ability of two or more public safety devices to communicate directly without the use of network infrastructure
*T. Doumi, M. F. Dolan, S. Tatesh, A. Casati, G. Tsirtsis, K. Anchan, and D. Flore, "LTE for public safety networks," IEEE Communications Magazine, vol. 51, pp. 106-112, 2013. 228
114 2013-09-05
LTE Enhancement for Public Safety
Direct Communication over LTE PTT: Push-To-Talk ProSe (Proximity Services) BM-SC: Broadcast multicast service center Device-to-device discovery and communication DTD (Device-to-Device) Communication One-to-one, one-to-many/unicast, one-to-many/broadcast, and one-hop relay functionalities Group Communication over LTE GCSE (Group Communication System Enablers) Low-latency communication bearer setup Priority access for group calls QoS for group call bearers eMBMS (enhanced Multimedia Broadcast Multicast Service) Broadcast capability Interface between PTT service application and BM-SC * 3GPP TR 22.803 V12.2.0, “Feasibility study for Proximity Services (ProSe) (Release 12),” 2013.06 * 3GPP TR 23.768 V0.2.0, “Study on architecture enhancements to support Group Communication System Enablers for LTE (GCSE_LTE) (Release 12) ,” 2013. 06 . 229
Public Safety Spectrum
**T. Doumi, M. F. Dolan, S. Tatesh, A. Casati, G. Tsirtsis, K. Anchan, and D. Flore, "LTE for public safety networks," IEEE Communications Magazine, vol. 51, pp. 106-112, 2013. 230
115 2013-09-05
Release 12 Issues Offloading WLAN Network Selection Device-to-Device Communications Machine Type Communication (MTC)
231
Machine Type Communication(MTC)
Machine Type Communication(MTC) Data communication with two or more objects Does not require human’s participation during communication Provide network connection to most/all ‘things’
Similar system : Wireless Sensor Network WPAN/WLAN/Ad-hoc based network Hard to provide QoS Mobility, end-to-end communication, compatibility problem It is not business area of network operators Install/maintenance by users hard to invest/maintain the system
MTC makes new business area to network operators
• 3GPP TS 22.368 v12.2.0, “Service Requirements for Machine-Type Communications(MTC)(Release 12),” 2013. 03. • 조수현, “KT Vision : M2M Services and Technologies”, KRNET 2011, 2011년 6월 27일. • 최상호, “SKT Vision : M2M Based Mobile Service”, KRNET 2011, 2011년 6월 27일. 232
116 2013-09-05
MTC Applications
Service Area MTC Applications
Security Surveillance systems, Backup for landline, Control of physical access(e.g. to buildings), Car/driver security
Tracking & Tracing Fleet management, Order management, Pay as you drive, Asset tracking, Navigation, Traffic information, Road tolling, Road traffic optimization/steering
Payment Point of sales, Vending machines, Gaming machines
Health Monitoring vital signs, Supporting the aged or handicapped, Web access telemedicine points, Remote diagnostics
Remote Maintenance/Control Sensors, Lighting, Pumps, Valves, Elevator control Vending machine control, Vehicle diagnostics
Metering Power, Gas, Water, Heating, Grid control, Industrial metering
Consumer Devices Digital photo frame, Digital camera, eBook
233 • 3GPP TS 22.368 v12.2.0, “Service Requirements for Machine-Type Communications(MTC)(Release 12),” 2013. 03.
Features/Requirements of MTC
Requirement Description
Low Mobility The network must provide simplified mobility management Time Controlled The network shall provide mechanisms than can send or receive data only during defined time intervals Small Data Transmissions The network shall support transmissions of small amounts of data with minimal network impact Infrequent Mobile Terminated The network shall be able to maintain information on when the MTC Device is not reachable MTC Monitoring The network shall provide mechanisms to detect several MTC related events Secure Connection The network shall provide network security for connection Group Based MTC Features The system shall be optimized to handle MTC Groups
234
117 2013-09-05
Communication Scenarios
MTC Devices communicating MTC Devices communicating with one or more MTC Server with each other
235 • 3GPP TS 22.368 v12.2.0, “Service Requirements for Machine-Type Communications(MTC)(Release 12),” 2013. 03.
Comparison between Machine-to-Machine(M2M) Communication and MTC
ETSI M2M Architecture 3GPP MTC Architecture
Other M2M : Can use M2M Network and gateway 3GPP : Path to Access No M2M Networks Networks Devices directly Can be any attached to 3GPP standardized network Access Networks system by 3GPP, TISAPN, IETF, etc
•TISAPN:Telecommunications and Internet converged Services and Protocols
•PDN:Packet Data Network •HSS:Home Subscriber Server •eNB:eNodeB •SM-SC:Short Message Service Centre•HPLMN:Home Public Land Mobile Network •RNC:Radio Network Controller •PGW:PDN Gateway •VPLMN:Visited Public Land Mobile Network •BSC:Base Station Controller 236 • 유상근, 홍용근, 김형준, “스마트모바일 서비스 –M2M 기술 및 표준 동향”, 전자통신동향분석 제 26권제2호, 2011년 4월.
118 2013-09-05
MTC in Release 10~11
Key Issue Description Rel-10 MTC subscriptions Activation/deactivation of MTC features Signaling congestion control MTC related signaling congestion and overload. 15 key issues were MTC device using a private non-routable IPv4 address IP addressing identified and thus not reachable by the MTC server. MTC device trigger MTC server polls data from MTC devices Signaling congestion Addressing issue due to the huge amount of MTC MTC identifiers devices and shortage of MSISDNs control and overload Grouping of MTC devices for ease of control, control Group based optimization management, charging facilities, etc., by the operators, and help in reducing redundant signaling. MTC devices frequently send or receive only small Online small data transmission amounts of data. MTC devices infrequently send or receive only small Rel-11 Offline small data transmission amounts of data. IP addressing MTC monitoring Monitoring of MTC devices in locations with high risk. Low Power Consumption Battery power saving for MTC devices. MTC identifiers MTC devices communicating Common service requirements for communication Device triggering with one or more MTC servers between MTC devices and MTC servers. Low mobility MTC device does not move frequently. Data transmission is only performed in a predefined Time controlled time period. Decoupling MTC server from MTC server may be deployed outside of the mobile 3GPP architecture network. Potential overload issues caused Imbalance of signaling vs. data traffic in the Visited by roaming MTC devices Public Land Mobile Network (VPLMN). • 3GPP TS 22.368 v12.2.0, “Service Requirements for Machine-Type Communications(MTC)(Release 12),” 2013. 03. • Andreas Kunz, “Machine Type Communications in 3GPP From Release 10 to Release 12”, GLOBECOM 2012 ONIT WS, Dec.237 2012
Signalling Congestion and Overload Control
Numerous devices make congestion even though they transmit small data Solution
Periodic Handling of Low access Attach with IMSI at PLMN PLMN search the invalid priority change time limit USIM state
Minimum time PLMN UE message can UE does not between forbidden lists be rejected, perform TAU searches for are kept even usage of with GUTI at waiting/back-off preferred if UE is PLMN change timers PLMN switched off is increased and on
• IMSI(International Mobile Subscriber Identity) : 가입자 ID(전화번호) • PLMN(Public Land Mobile Network) : 네트워크 식별번호 • TAU(Tracking Area Update) 238 • GUTI(Globally Unique Temporary Identifier) : 사용자의 임시 ID
119 2013-09-05
MTC Device Identifiers/Addressing
Objective Assign ID and address to MTC devices to enable a MTC server in a public addressing domain to send messages to a MTC device in a private addressing domain Solution Identifier 15-digit IMSI telephone number for large-scale deployment Addressing IPv6 addressing IPv4 addressing with private IPv4 domain
Private IPv4 Address Space IPv4 Address Space
MTC MTC Device MNO Server
239 • MNO : Mobile Network Operator
MTC in Release 12
Rel-12 Key Issue Description MTC subscriptions Activation/deactivation of MTC features Triggering Signaling congestion control MTC related signaling congestion and overload. MTC device using a private non-routable IPv4 address IP addressing enhancements and thus not reachable by the MTC server. MTC device trigger MTC server polls data from MTC devices Group based features Addressing issue due to the huge amount of MTC MTC identifiers devices and shortage of MSISDNs Small data Grouping of MTC devices for ease of control, transmission Group based optimization management, charging facilities, etc., by the operators, and help in reducing redundant signaling. MTC devices frequently send or receive only small Monitoring Online small data transmission amounts of data. UE power MTC devices infrequently send or receive only small Offline small data transmission consumptions amounts of data. MTC monitoring Monitoring of MTC devices in locations with high risk. optimizations Low Power Consumption Battery power saving for MTC devices. MTC devices communicating wit Common service requirements for communication h one or more MTC servers between MTC devices and MTC servers. Low mobility MTC device does not move frequently. Data transmission is only performed in a predefined Time controlled time period. Decoupling MTC server from 3G MTC server may be deployed outside of the mobile PP architecture network. Potential overload issues caused Imbalance of signalling vs. data traffic in the Visited by roaming MTC devices Public Land Mobile Network (VPLMN). 240
120 2013-09-05
Outlook of MTC in 3GPP Release 12
Triggering enhancements intended for device triggering by using reference points between MTC-IWF and serving nodes (i.e., SGSN, MME, and MSC), as well as triggering efficiency optimizations. Group based features optimizations to a group of MTC UEs that share one or more MTC features. Small data transmission intended for use with MTC UEs that send or receive small amounts of data. Also, frequent small data transmission will be considered. Monitoring intended for monitoring MTC UE related events such as loss of connectivity, change of the location of MTC UE, etc. UE power consumptions optimizations intended for optimizations to prevent battery drain of MTC UEs.
• MTC-IWF : Interworking function between (external) MTC Server and operator core network 241
Summary
242
121 2013-09-05
Summary
3GPP LTE Network Architecture
User Plane Protocol • Packet Data Convergence Protocol / Radio Link Control / Medium Access Control Control Plane Protocol • Radio Resource Control / Mobility control / Radio Resource Management LTE-Advanced Features • Heterogeneous Networks / Carrier Aggregation / CoMP Release 12 Issues • Offloading / WLAN Network Selection / Device-to-Device Communications / Machine Type Communication
243
Thank you !
Q & A
244
122 2013-09-05
References
3GPP TS 36.300 V11.6.0 "E-UTRA and E-UTRAN; Overall description", June, 2013 3GPP TS 23.203 v12.1.0, "Policy and charging control architecture," Jun. 2013. 3GPP TS 36.323 v11.2.0, "Evolved Universal Terrestrial Radio Access (E-UTRA); Packet Data Convergence Protocol (PDCP) specification(Release 11) ", April, 2013 acticom mobile networks, http://www.acticom.de/en/ 3GLTEINFO, http://www.3glteinfo.com/lte-security-architecture-20110325/ A. Larmo et al., "The LTE link-layer design," Communications Magazine, IEEE , April 2009. 3GPP TS 36.321 V11.3.0, "Medium Access Control (MAC) protocol specification (Release 11)", Jun, 2013. 3GPP TS 24.301 V10.7.0, "UMTS; LTE; NAS; EPS; Stage 3", July, 2012 3GPP TS 24.401 V8.9.0, "LTE; GPRS enhancements for E-UTRAN access", March, 2010 3GPP TS 36.331 V10.5.0, "Radio Resource Control (RRC) Protocol specification (Release 10)," ed, 2012. Netmanias, "EMM and ECM States," http://www.netmanias.com, 2013. Bong Youl (Vrian) Cho, "LTE RRC/RRM", TTA LTE/MIMO Standards/Technology Training, May 2012 3GPP TS 36.213 v10.6.0 "LTE Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures (Release 10)," July 2012. Netmanias, "EMM Procedure: 1. Initial Attach for Unknown UE (2편)," September, 2011 http://www.netmanias.com/bbs/view.php?id=techdocs&no=74 윤영우, "3GPP LTE Rel-12 & Onwards 주요 요소 기술 및 표준 동향", 전자공학회지, 제 40권 4호, pp.328-339, 2013년 4 월 3GPP, RWS-120046, Samsung Electronics, "Technologies for Rel-12 and Onwards," June 2012. 3GPP, RWS-120010, NTT DOCOMO, "Requirements, Candidate Solutions & Technology Roadmap for LTE Rel-12 Onward," June 2012. C. H. Lee and J. H. Kim, "Parallel Measurement Method of System Information for 3GPP LTE Femtocell," in Proc. ICNS 2011, Venice, Italia, 22-27. May 2011. Informa Telecoms & Media, "Small cell Market Status," 2013. 2. J.Wannstrom, "Carrier Aggregation explained", http://www.3gpp.org/Carrier-Aggregation-explained , May, 2012 SKT hompage, "SK텔레콤, 30일 84개시 중심가로 ‘LTE-A’ 확대", http://www.sktelecom.com, July, 2013. LGU+ homepage, "LG유플러스, 세계 최초 ‘100% LTE’ 상용화", www.uplus.co.kr, July, 2013. 윤영우, "LTE-Advanced 표준 기술 (REL-10 동향 및 REL-11 전망)", 한국통신학회지(정보와통신), 2011.5 S.Seia, I. Toufik, M. Baker, "LTE The UMTS Long Term Evolution –From Theory to Practice, Second Edition".
245
References
NTT DOCOMO, "R1-090314: Investigation on Coordinated Multipoint Transmission Schemes in LTE-Advanced Downlink", www.3gpp.org, 3GPP TSG RAN WG1, meeting 55bis, Ljubljana, Slovenia, January 2009. 김지수, 김재현 "기지국 협력 통신 네트워크 효율성 성능평가," in Proc. 한국통신학회 하계학술대회 , 제주도, 2010년 06월. 김현숙, "3GPP Traffic Offload", FMC 포럼 컨버젼스 기술 및 표준 워크샵, 2012. 12. 12. NEC corporation, "Mobile Traffic Offload: NEC’s Cloud Centric Approach to Future Mobile Networks," 2013. 04. Konstantinos Samdanis, Tarik Taleb, Stefan Schmid, "Traffic Offload Enhancements for eUTRAN," IEEE COMMUNICATIONS SURVEYS & TUTORIAL, 2012. 3GPP TR 23.829 V10.0.1, "3GPP technical specification group services and system aspects; local IP access and selected IP traffic offload (Release 10)," 2011. 10. 3GPP TS 23.402 V12.1.0, "Architecture enhancements for non-3GPP accesses", June 2013. 3GPP TS 24.312 V12.1.0, "Access Network Discovery and Selection Function (ANDSF) Management Object (MO)", June 2013. 3GPP TS 23.865 V1.0.0, "WLAN network selection for 3GPP termianls", June 2013. L. Lei, Z. Zhangdui, L. Chuang, and S. Xuemin, "Operator controlled device-to-device communications in LTE- advanced networks," IEEE Wireless Communications, vol. 19, pp. 96-104, 2012. 3GPP TR 22.803 V12.2.0, "Feasibility study for Proximity Services (ProSe) (Release 12)," 2013.06 3GPP TS 22.368 V12.2.0, "Service requirements for Machine-Type Communications (MTC);Stage 1(Release 12)," 2013. 03 3GPP TR 23.887 V1.0.0, "Machine-Type and other Mobile Data Applications Communications Enhancements (Release 12)," 2013. 06. S2-131505 "Solution for direct discovery and communication", April, 2013 T. Doumi, M. F. Dolan, S. Tatesh, A. Casati, G. Tsirtsis, K. Anchan, and D. Flore, "LTE for public safety networks," IEEE Communications Magazine, vol. 51, pp. 106-112, 2013. Government Technology white paper, "A How-To Guide for LTE in Public Safety," 2010 3GPP TR 23.768 V0.2.0, "Study on architecture enhancements to support Group Communication System Enablers for LTE (GCSE_LTE) (Release 12) ," 2013. 06 . 조수현, "KT Vision : M2M Services and Technologies", KRNET 2011, 2011년 6월 27일. 최상호, "SKT Vision : M2M Based Mobile Service", KRNET 2011, 2011년 6월 27일. 유상근, 홍용근, 김형준, "스마트모바일 서비스 – M2M 기술 및 표준 동향", 전자통신동향분석 제 26권 제 2호, 2011년 4월. Andreas Kunz, "Machine Type Communications in 3GPP From Release 10 to Release 12", GLOBECOM 2012 ONIT WS, Dec. 2012
246
123