Introduction

1 Reference

[1] Wireless and Mobile Network Architectures，Yi-Bing Lin and Imrich Chlamtac，Wiley Computer Publishing。 [2] Introduction to GSM，陳俊宏，遠傳教育訓練 中心。 [3] GPRS and 3G Wireless Applications， Christoffer Andersson，Wiley Computer Publishing。

2 Outline

¾ Introduction ¾ PCS Architecture ¾ Cellular Telephony ¾ Cordless Telephony and Low-Tier PCS ¾ Third-Generation Wireless Systems ¾ Summary

3 Introduction

4 PCS

¾ Personal Communications Services (PCS) refers to a wide variety of wireless access and personal mobility services. ¾ PCS systems can connected to Public Switched Telephone Network (PSTN). ¾ Goal of PCS：enabling communications with a person at anytime, at any place and in any terminal form.

5 PCS Revolution First Generation Second Generation Third Generation

JTACS Mobile Satellite JDC High-tier TACS Digit GSM GSM+,++ Cellar NMT Systems IMT-2000 AMPS NADC PCS

Low-tier PHS Telecommunication PACS Systems CT0/1 CT2 DECT 6 Examples of Wireless Communications Systems (1/4) ¾ High-tier digital cellular systems ¾ For vehicular and pedestrian services • Global System for Mobile Communication (GSM), Digital Communication System-1800 (DCS1800) • IS-136 TDMA based Digital Advanced Mobile Phone Service (DAMPS) • Personal Digital Cellular (PDC) • IS-95 CDMA-based cdmaOne System

7 Examples of Wireless Communications Systems (2/4) ¾ Low-tier telecommunication systems ¾ For residential, business, and public cordless access applications • Cordless Telephone 2 (CT2) • Digital European Cordless Telephone (DECT) • Personal Access Communications Systems (PACS) • Personal Handy Phone System (PHS)

8 Examples of Wireless Communications Systems (3/4) ¾ Wideband wireless systems ¾ To accommodate Internet and multimedia services. • cdma2000 (evolved from cdmaOne) • W-CDMA (proposed by Europe) • TD-SCDMA (proposed by China/Europe)

9 Examples of Wireless Communications Systems (4/4) ¾ PCS umbrella • Paging systems • Trunking Radio • Mobile-satellite system • Unlicensed industrial, scientific, and medical （ISM）band technologies, as well as wireless local area networks（WLANs）

10 PCS Architecture

11 PSTN

¾ Public Switched Telephone Network

Switch Taichung

subscriber loop Switch trunk Switch Taipei

12 PLMN

¾ Public Land Mobile Network

PLMN

PSTN

13 The Basic PCS Architecture

Mobility Wireline Transport Network Public Land Database Mobile Network

Switch for Mobile Applications Base Station Controller Base Transceiver Station

BTS Radio Network Mobile Station 14 PCS Architecture

¾ Each PCS technology has similar architectures which consists two parts： •Radio Network 9MS (Mobile Station) 9BS (Base Station) System • Wireline Transport Network 9MSC (Mobile Switching Center) 9The Mobility Database connected to MSC is used to track the locations of mobile station.

15 Mobile Station (MS)

¾ Handset, mobile phone, subscriber unit, portable ¾ Multi-mode handset

16 Base Station (BS)

¾ The radio coverage of a BS is called a Cell. ¾ The BS system is partitioned into • a controller • radio transmitters/receivers ¾ The BSs usually reach the wireline core network via land links or dedicated microwave 17 links. GSM Antenna

18 GSM Base Station

19 Cellular Concept

cluster

√ √ √ cell

sector

√ √ √

20 Duplex Technologies

¾ Down-link: BS to handset ¾ Up-link: handset to BS ¾ Two duplex Technologies: •FDD（Frequency Division Duplex） •TDD（Time Division Duplex）

21 FDD

Frequency

A1 talks to A2 B1 talks to B2 Down Link C1 talks to C2

A2 talks to A1 Up B2 talks to B1 Link C2 talks to C1 Time 22 TDD Frequency

A2 B2 C2 A1 B1 C1 talks talks talks talks talks talks to to to to to to A1 B1 C1 A2 B2 C2

......

Time

23 Multiple Access Technology

¾ FDMA（Frequency Division Multiple Access） ¾ TDMA（Time Division Multiple Access） ¾ CDMA（Code Division Multiple Access）

24 FDMA Frequency

30kHz for AMPS

Time 25 TDMA Frequency

200kHz for GSM

Time 4.615 ms/frame 8 time slots for GSM 26 CDMA (1/2) Frequency

1.25MHz for IS-95

20 ms/frame 32 channels 27 CDMA (2/2)

¾ Code Division Multiple Access (CDMA) • Direct Sequence Spread Spectrum (DSSS) • Frequency Hopping Spread Spectrum (FHSS) ¾ In DS-CDMA, every signal is processed with PN sequence (pseudo-noise sequence). • Faster-rate, wide-bandwidth digital signal • Each PN sequence is a unique orthogonal code. • User signals are distinguished by different PN sequences.

28 Example of PN (1/3)

¾ Assign PN code A: 00011011, B: 00101110, C: 01011100, D: 01000010 ¾ Transfer the PN to Bipolar chip sequences: • A=(-1,-1,-1,1,1,-1,1,1) B=(-1,-1,1,-1,1,1,1,-1) • C=(-1,1,-1,1,1,1,-1,-1) D=(-1,1,-1,-1,-1,-1,1,-1) ¾ Check: • A*A=1+1+1+1+1+1+1+1=8 • A*B=1+1-1-1+1-1+1-1=0 • A*C=1-1+1+1+1-1-1-1=0

• A*D=1-1+1-1-1+1+1-1=0 29 Example of PN (2/3)

¾ If 4 MSs want to receive A=1, B=1, C=1, D=1, then BS will send • S1=A*1+B*1+C*1+D*1=(-4,0,-2,0,2,0,2,-2) ¾ If 4 MSs want to receive A=1, B=1, C=0, D=1, then BS will send • S2 =A*1+B*1+C*(-1)+D*1 =(-2,-2,0,-2,0,-2,4,0)

30 Example of PN (3/3)

¾ MS C will receive •1/8* C*S1 = 1/8 * (-4,0,-2,0,2,0,2,-2) * (-1,1,-1,1, 1,1,-1,-1) = 1/8 * (4+0+2+0+2+0-2+2)= 1 • 1/8 * C*S2 = 1/8 * (-2,-2,0,-2,0,-2,4,0) * (-1,1,-1,1, 1,1,-1,-1) = 1/8 * (2-2+0-2+0-2-4+0)= -1 9-1 means “0” ¾ MS A will receive • A*S1=A*(A*1+B*1+C*1+D*1)=A*A*1+A*B*1+A*C*1 31 +A*D*1=8*1+0+0+0=8 Spread Spectrum Correlation Process

Recovered Data Signal Received Signal + Wideband Interference Data Signal

W Hz Direct Sequence Direct Sequence Spread Despread

0 f 0 f 0 f

: Desired Signal

: Interference

32 Cellular Telephony

33 1G Cellular Telephony

¾ Advanced Mobile Phone Service (AMPS) ¾ Total Access Communication System (TACS) ¾ NMT (Nordic Mobile Telephone) 450/900 ¾ NTT (Nippon Telephone & Telegraph) , JTACS (1988), NTACS (1993) ¾ C450

34 Advanced Mobile Phone Service (AMPS) (1/2) ¾ Analog FM radio for voice transmission ¾ FSK modulation for signal channels ¾ FDMA ¾ FDD ¾ Total 50 MHz=824-849 MHz(down-link) + 869-894 MHz(up-link) • 832 full-duplex channels using 1664 discrete frequencies ¾ 30kMHz spacing

35 Advanced Mobile Phone Service (AMPS) (2/2) ¾ Frequency reuse scheme for radio communication • 12-cell cluster using omni-directional antennas • 7-cell cluster using three sectors per BS • 4-cell cluster, 6-sector design in Motorola AMPS system. There are about 50 channels per cell. ¾ EIA/TIA IS-41 standard for roaming management.

36 2G Cellular Telephony

¾ Global System for Mobile Communications (GSM) ¾ EIA/TIA IS-136 Digital Cellular System ¾ EIA/TIA IS-95 Digital Cellular System ¾ Japanese Digital Cellular (JDC) in Japan

37 Global System for Mobile Communications (GSM) (1/2) ¾ “Digital” cellular system • Groupe Special Mobile of Conference Europeenne des Posts et Telecommunications (CEPT) and European des Postes et Telecommunications (ETSI) ¾ TDMA/FDD ¾ 935-960 MHz for Downlink ¾ 890-915 MHz for Uplink ¾ 200 kHz for RF channel spacing ¾ Speech coding rate 13 Kbps 38 Global System for Mobile Communication (GSM) (2/2) ¾ Frequency carrier is divided into 8 time slots • Every pair of radio transceiver-receiver supports 8 voice channels. ¾ GSM Mobile Application Part (MAP) for roaming management ¾ Digital switch can provide many applications: • Example: point-to-point short messaging, group addressing, call waiting, multiparty services

39 EIA/TIA IS-136 Digital Cellular System (1/2) ¾ Digital AMPS (DAMPS), American Digital Cellular (ADC), or North American TDMA (NA-TDMA), IS-136 ¾ The successor to IS-54 ¾ The same spectrum used by AMPS • 3 times of capacity of AMPS ¾ TDMA/FDD ¾ 30 KHz frequency spacing

40 EIA/TIA IS-136 Digital Cellular System (2/2) ¾ 2 types of channel usage: • Full-rate: use 2 timeslot for a voice channel • Half-rate: use 1 timeslot for a voice channel ¾ Digital switch can provide many applications: • Example: point-to-point short messaging, broadcast messaging, group addressing, private user groups ¾ IS-41 standard for mobility management

41 EIA/TIA IS-95 Digital Cellular System (1/2) ¾ Qualcomm cdmaOne in USA since 1996 ¾ Korea in April, 1996.

PLMN

Vocoder

Switch PSTN

42 EIA/TIA IS-95 Digital Cellular System (2/2)

¾ CDMA/DSSS for the air interface. • A shared 1.25 MHz channel bandwidth • User signals distinguished with different codes • MSs links to many BSs during phone calls. • No cell plan question • GPS for synchronization of BSs ¾ Interference-based capacity (soft capacity) • The capacity of IS-95 is 3-6 times of IS-136 system, and 10 times of AMPS. ¾ IS-41 for core network

¾ Advanced Radio Resource Management 43 Comparison of Cellular Systems

System AMPS GSM IS-136 IS-95 JDC DCS1800 Region 美 歐,台灣 美 美,韓,中國 日 Duplex FDD FDD FDD FDD FDD MAC FDMA FDMA FDMA FDMA FDMA TDMA TDMA CDMA TDMA Downlink 870-890 935-960 869-894 869-894 810-826 (MHz) 1805-1880 Uplink (MHz) 825-845 890-915 824-849 824-849 940-956 1710-1785 Carrier 30kHz 200kHz 30kHz 1.25MHz 25kHz Channels 1 8 6 32 3 Speech rate 10 kps 13 kps 7.95kps 8 kps 11.2 kps Channel bit 270.833 kps 48.6 kps 1228.8 kps 42 kps rate 44 Cellular Characteristics

¾ The characteristics of the cellular system: • Support high mobility • Large coverage area • High transmission power of BS and handset • High signal process power (for handset) • Low voice quality • High network complexity ¾ Microcell is developed for: • Low transmission power • Low base station cost 45 • Increase capacity Low-Tier PCS

46 Examples of Low-Tier PCS

¾ Cordless Telephone, Second Generation (CT2) ¾ Digital European Cordless Telephone (DECT) ¾ Personal Handy Phone System (PHS) ¾ Personal Access Communications System (PACS)

47 Cordless Telephone, Second Generation (CT2) (1/2)

¾ Developed in Europe CT-1 since 1989. ¾ 40 FDMA channels CT-1+ ¾ 32-Kbps speech coding rate CT-2 ¾ TDD ¾ The maximum transmit CT-2+ power of a CT2 handset is 10 mW

CT-3 48 Cordless Telephone, Second Generation (CT2) (2/2)

¾ No handoff in CT2 ¾ No call delivery in CT2 ¾ In CT2+, both handoff and call delivery are OK.

49 Digital European Cordless Telephone (DECT) (1/2)

¾ Published in 1992 ¾ TDMA/TDD ¾ 12 voice channels per frequency carrier ¾ Sleep mode is employed in DECT to conserve the power of handsets. ¾ 32 Kbps speech coding rate

50 Digital European Cordless Telephone (DECT) (2/2)

¾ DECT is typically implemented as a wireless- PBX connected to the PSTN. ¾ Dynamic channel allocation ¾ Time slot transfer ¾ Seamless handoff ¾ Dual mode: DECT + GSM

51 Personal Handy Phone System (PHS) (1/2) ¾ Developed by Research and Development Center (RCR), Japan 1993 ¾ Telecommunication services for homes, offices, and outdoor environment ¾ TDMA/TDD ¾ 4 multiplexed channels/frequency carrier ¾ 1895-1906.1 MHz = 300 KHz × 37 channels (home/office) ¾ 1906.1-1918.1 MHz = 300 KHz × 40 channels (public system) 52 Personal Handy Phone System (PHS) (2/2) ¾ BS: 500 mW; handset < 10mW ¾ 32 Kbps speech coding rate ¾ Dynamic channel allocation. ¾ Dedicated control channels ¾ Sleep Mode ¾ J100: 7 hours talk time, 700 hours standby time, 64kbps wireless data ¾ Dual mode: PHS + GSM

53 Personal Access Communications System (PACS)

¾ Developed at Telcordia, U.S.A. ¾ PACS is designed for wireless local loop and PCS. ¾ TDMA ¾ 8 voice channels/frequency carrier ¾ Both TDD and FDD are accommodated. ¾ The highly effective and reliable mobile- controlled handoff (MCHO) completes in less than 20 msec.

54 Comparison of PCS Systems

System CT-2 DECT PHS PACS

Region 歐,台灣 歐 日本 美 Duplex TDD TDD TDD FDD MAC FDMA FDMA FDMA FDMA TDMA TDMA TDMA Frequency 864-868 1880-1900 1895-1918 1930-1990(down) (MHz) 1850-1910(uplink) Carrier 100kHz 1728kHz 300kHz 300MHz Channels 1 24 8 8 Speech rate 32kps 32kps 32kps 32kps Channel bit 72kps 1152kps 384kps 384kps rate

55 Low-tier PCS Characteristics

¾ The characteristics of the low-tier system: • Low transmission power • Long talk time • Small coverage area • Large no. of base station • Low transmission delay • High voice quality • Low mobility • Low network complexity • Low cost 56 Characteristics of Cellular and Cordless Low-Tier PCS Technologies

Systems HIGH-TIER LOW-TIER PCS CORDLESS CELLULAR Cell Size Large(0.5-35 Km) Medium(50-500 m) Small(50-100m) User Speed High(<=257Km/hr) Medium(<=96Km/hr) Low(<=48Km/hr) Coverage Area Large/Continuous Medium Small/Zonal macro cells micro and picocells picocells Handset High Low Low Complexity Handset power High (100-800mW) Low (5-10mW) Low (5-10mW) consumption Speech Coding Low (8-13Kbps) High (32Kbps) High (32Kbps) Rate Delay or High (<= 600ms) Low (<= 10ms) Low (<=20ms) Latency

57 Third-Generation Wireless System

58 Generations of Wireless Systems

¾ First Generation System: AMPS • Analog voice calls ¾ Second Generation Systems: GSM, IS-136, IS-95, and low-tier systems • Digital speech with low-bit-rate data services ¾ Third-Generation: • Better system capacity • High-speed and wireless Internet access (to 2Mbps) • Wireless multimedia services (audio and video)

59 Third-Generation Wireless Systems

¾ 2.5G: GPRS and EDGE • Bridge 2G into 3G ¾ The new features for 3G includes • High bit rates, QoS, Bit rates dependent on distance • Asynchronous Transfer Mode (ATM) backbone • Wideband CDMA (DS-CDMA FDD), SCDMA and cdma2000 (multi-carrier FDD) for air interface

60 3G Revolution 2 G 2.5G 3G

America IS-95A IS-95B cdma2000 Cdma2000 3xMC 1x

IS-136 ? 1xEV-DO 1xEV-DV

EDGE

UMTS/ GSM GSM GPRS UMTS Europe HSDPA

Japan PDC P-PDC W-CDMA 61 Summary

¾ PCS Architecture ¾ Cellular Telephony ¾ Cordless Telephony and Low-Tier PCS ¾ Third-Generation Wireless Systems

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