Delay analysis of PoC service solutions for Public Safety communications over LTE networks DELAY ANALYSIS OF PUSH -TO -TALK OVER CELLULAR (P OC) SERVICE SOLUTIONS FOR PUBLIC SAFETY COMMUNICATIONS OVER LTE NETWORKS Author: Chengsui Lu Date: 27 August, 2012 Abstract – In this master thesis, the concept of public safety communication solutions over modern commercial cellular systems is presented, and the delay analysis for Puch-to-Talk over Cellular (PoC) service is provided especially for the LTE and IMS networks. Firstly, the motivations and requirements of public safety communications using commercial cellular technology are studied and introduced. Secondly, the 3GPP IMS-based public safety communication network architecture and the PoC service are described in details. Thirdly, we make a survey of the PoC delay targets for modern emergency communication networks. Finally, the call set-up delay and end to end delay calculations are done by dividing into latency components of each network entities. Our analysis shows that typical call set-up time and end to end delay are within 275 milliseconds and 250 milliseconds respectively, and the mainstream LTE cellular technology can be designed to satisfy the stringent time constraints for public safety purpose, making LTE a promising option for public safety communications. Key words: Public Safety communication networks; delay analysis; LTE; call setup time; end to end latency; IMS. 1/48 Delay analysis of PoC service solutions for Public Safety communications over LTE networks TABLE OF ACRONYMS Acronym Description 3G Thirrd Generation 3GPP 3rd Generation Partnership Project AKA Authentication and Key Agreement AMR Adaptive Multi-Rate APCO Association of Public-safety Communications Officials-International ARPU Average Revenue Per User B3G Beyond 3G BLER Block Error Rate BTS Base Transceiver Station CAI Common Air Interface CAPEX CAPital EXpenditure CDMA Code Division Multiple Access CN Core Network CPC Continuous Packet Connectivity CSCF Call Session Control Function DHS Department of Homeland Security DMO Direct Mode Operation DnD Do-not-Disturb EPC Evolved Packet Core EPS Evolved Packet System ETSI European Telecommunications Standards Institute E-UTRAN Evolved-UMTS Terrestrial Radio Access Network FCC Federal Communications Commission FMO Future Mode of Operation GGSN Gateway GPRS Support Node GLMS Group and List Management Server GoS Grades of Service GoTa Global open Trunking architecture 2/48 Delay analysis of PoC service solutions for Public Safety communications over LTE networks GPRS General packet radio service GSM Global System of Mobile communication H-ARQ Hybrid-Automatic Repeat reQuest HSS Home Subscriber Server HTTP HyperText Transfer Protocol IA Information Assurance I-CSCF Interrogating-Call Session Control Function iDEN integrated Digital Enhanced Network IETF Internet Engineering Task Force IM Instant Messages IMS IP Multimedia Subsystem IP Internet Protocol IP-CAN IP Connectivity Access Network IPSec IP Security ITU International Telecommunications Union LTE Long Term Evolution MBMS Multimedia Broadcast/Multicast Services MESA Mobility for Emergency and Safety Applications MITM Man-In-The-Middle attacks MME Mobility Management Entity MS Mobile Station MTSI Multimedia Telephony Service over IMS NPSTC National Public Safety Telecommunications Council OMA Open Mobile Alliance OPEX OPerating EXpense OSI Open Systems Interconnection PCC Policy and Charging Control P-CSCF Proxy-Call Session Control Function PDA Personal Digital Assistant PDN GW Packet Data Network GateWay PMO Present Mode of Operation 3/48 Delay analysis of PoC service solutions for Public Safety communications over LTE networks PMR Professional Mobile Radio PoC Push to talk over Cellular PS Packet Switch PSS Public Safety and Security PTT Push To Talk PWS Public Warning Systems QCI QoS class identifier QoS Quality of Service RAN Radio Access Network RF Radio Frequency RNC Radio Network Controller RNS Radio Network System RRM Radio Resource Management RTCP Real-time Transport Control Protocol RTP Real-time Transport Protocol RTT Round-Trip Time SA Security Associations SAE System Architecture Evolution S-CSCF Serving-Call Session Control Function SCTP Stream Control Transmission Protocol SGSN Serving GPRS Support Node S-GW Serving GateWay SIB System Information Block SIP Session Initiation Protocol SMS Short Message Service TIA Telecommunications Industry Association TCO Total Cost of Ownership TCP Transmission Control Protocol TETRA TErrestrial TRunked Radio TISPAN Telecommunications and Internet converged Services and Protocols for Advanced Networking TTI Transmission Time Interval 4/48 Delay analysis of PoC service solutions for Public Safety communications over LTE networks UDP User Datagram Protocol UE User Equipment UHF Ultra High Frequency UMTS Universal Mobile Telecommunications System UPSF User Profile Server Function UTRAN UMTS Terrestrial Radio Access Network VHF Very High Frequency VoIP Voice over IP WiFi Wireless Fidelity XDMS XML Document Management Server XML eXtensible Markup Language 5/48 Delay analysis of PoC service solutions for Public Safety communications over LTE networks TABLE OF CONTENTS 1. INTRODUCTION ................................................................................................................................. 10 1.1 TECHNOLOGICAL TRENDS IN PUBLIC SAFETY COMMUNICATION NETWORKS ................................ 10 1.2 KEY BENEFITS OF ADOPTING MAINSTREAM CELLULAR TECHNOLOGY ............................................ 11 1.3 CHALLENGES AND OPPORTUNITIES ................................................................................................. 12 1.4 OBJECTIVES ..................................................................................................................................... 12 1.5 RELATED WORKS ............................................................................................................................. 13 1.6 THESIS OUTLINE ............................................................................................................................... 13 2. TECHNICAL REQUIREMENTS ........................................................................................................... 14 2.1 GENERAL REQUIREMENTS ............................................................................................................... 14 2.1.1 Basic and specialized services .............................................................................................. 14 2.1.2 Network availability ............................................................................................................. 15 2.1.3 Coverage ............................................................................................................................... 15 2.1.4 Capacity ................................................................................................................................ 15 2.1.5 Interoperability ..................................................................................................................... 15 2.1.6 Secure scheme ...................................................................................................................... 15 2.1.7 Call setup time ...................................................................................................................... 15 2.1.8 Voice quality ........................................................................................................................ 15 2.2 POC OVER LTE REQUIREMENTS ...................................................................................................... 16 3. IMS-BASED PUBLIC SAFETY COMMUNICATION NETWORK SOLUTION ....................................... 17 3.1 OVERVIEW : IMS CORE AND 3GPP IP-CAN .................................................................................... 17 3.2 FUNCTIONAL ENTITIES ..................................................................................................................... 18 3.2.1 IM Subsystem ....................................................................................................................... 18 3.2.2 IP Connectivity Access Network (IP-CAN) ......................................................................... 18 3.3 IMS APPLICATIONS ......................................................................................................................... 19 3.3.1 PoC services ......................................................................................................................... 20 3.3.2 PoC architecture ................................................................................................................... 20 3.3.3 PoC protocols ....................................................................................................................... 21 3.3.4 PoC procedures..................................................................................................................... 21 4. DELAY ANALYSIS ............................................................................................................................. 24 4.1 POC DELAY TARGETS ...................................................................................................................... 24 4.1.1 Delay targets in commercial mobile networks ..................................................................... 24 4.1.2 Delay targets for public safety communication networks ...................................................