Reference PCS

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PCS

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Reference

Wireless and Mobile Network Architectures，

Y-Bing Lin and Imrich Chlamtac，

Wiley Computer Publishing

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Outlines

¾ Introduction

¾ PCS Architecture

¾ Cellular Telephony

¾ Cordless Telephony and Low-Tier PCS

¾ Third-Generation Wireless Systems

¾ Summary

Introduction

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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.

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PCS Revolution

JTACS

First Generation Second Generation Third Generation

High-tier Digit Cellar Systems

Low-tier

Telecommunication Systems

TACS

AMPS

GSM

CT0/1

PHS

CT2 PACS

DECT JDC

NADC PCS

NMT IMT-2000

GSM+

Mobile Satellite

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PCS Revolution

JTACS

First Generation Second Generation Third Generation

High-tier Digit Cellar Systems

Low-tier

Telecommunication Systems

TACS

AMPS

GSM

CT0/1

PHS

CT2 PACS

DECT JDC

NADC PCS

NMT IMT-2000

GSM+

Mobile Satellite

HSCSD: High Speed Circuit Switched Data GPRS: packet switching

ITU:

International Telecommunications Union

4G?

WLAN+GPRS

Examples of Wireless

Communications Systems (1/4)

¾ High-tier digital cellular systems

¾ For vehicular and pedestrian services

• Europe：

Global System for Mobile Communication (GSM), Digital Communication System-1800 (DCS1800)

• USA：

IS-136 TDMA based Digital Advanced Mobile Phone Service (DAMPS)

IS-95 CDMA-based cdmaOne System

• Japan：

Personal Digital Cellular (PDC)

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Examples of Wireless

Communications Systems (2/4)

¾ Low-tier telecommunication systems

¾ For residential, business, and public cordless access applications

• Europe, Asia：

Cordless Telephone 2 (CT2)

Digital European Cordless Telephone (DECT)

• USA：

Personal Access Communications Systems (PACS)

• Japan：

Personal Handy Phone System (PHS)

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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)

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Examples of Wireless

Communications Systems (4/4)

¾ PCS umbrella

• Paging systems (90’s BB call)

• Specialized Mobile Radio (taxi calling)

• Mobile-satellite system

• Unlicensed industrial, scientific, and medical

（ISM）band technologies, as well as wireless local area networks(WLANs)

PCS Architecture

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PSTN

¾ Public Switched Telephone Network

Switch

Switch Taipei

Taichung

trunk subscriber loop

Ex.: Chunghwa Telecom

Trunk:

1. SS7 2. voice

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PLMN

¾ Public Land Mobile Network

PSTN PLMN

Ex.: Far Eastone Telecom

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The Basic PCS Architecture

Public Land Mobile Network

Switch for Mobile Applications

Mobility Database

Base Station Controller

Mobile Station BTS

Radio Network

Wireline Transport Network

Base Transceiver Station

MSC：

Mobile Switching Center

BS: base station

PCS Architecture

¾ Each PCS technology has similar

architectures which consists two parts：

• Radio Network

9 MS (Mobile Station) 9 BS (Base Station) System

• Wireline Transport Network

9 MSC (Mobile Switching Center)

9 The Mobility Databaseconnected to MSC is used to track the locations of mobile station.

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Mobile Station (MS)

¾ Handset,

¾ mobile phone,

¾ subscriber unit,

¾ portable (low-tier systems)

¾ 行動電話

¾ 手機

¾ 大哥大

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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

links.

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GSM Antenna

GSM Base Station

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Cellular Concept

cluster

sector

√ cell

√

√ √

√

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Cellular Concept

In AMPS：

◎ 12-group frequency cluster

◎ 7-group cluster

？一個固定大小的區域中, 究竟能佈置多少 cell?

理論上由 1 到無限多個 cells 都可以, 但實際上:

以 GSM 為例, cell sizeu, capacity v

no. of cells u (cell size v) > Frequency reuse factor u, >

system capacity u

(handoff, location tracking) > Cell size v time u

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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）

FDD

Frequency

A1 talks to A2 B1 talks to B2

B2 talks to B1 A2 talks to A1

C2 talks to C1 C1 talks to C2

Down Link

Up Link

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TDD

Frequency

Time

A2 talks to A1

C2 talks to C1 B2 talks to B1

A1 talks to A2

C1 talks to C2 B1 talks to B2

... ...

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Multiple Access Technology

¾ FDMA（Frequency Division Multiple Access）

¾ TDMA（Time Division Multiple Access）

¾ CDMA（Code Division Multiple Access）

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FDMA

Frequency

Time 30kHz

for AMPS

TDMA

Frequency

Time 200kHz

for GSM

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CDMA (1/2)

Frequency

20 ms/frame 32 channels 1.25MHz

for IS-95

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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.

CDMA (2/2)

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31 Data Signal

0 f

: Desired Signal : Interference

0 W Hz

f Received Signal + Wideband Interference

Recovered Data Signal

0 f

Direct Sequence Spread

Direct Sequence Despread

Spread Spectrum Correlation Process

Cellular Telephony

High-tier – cellular telephone

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◎1920年底特律警車使用最早的”行動電話”, 只有單向廣播功能. 1930 早期, 才有雙向的系統開始運作.

◎ 1930年代, 第一個FM的行動電話才開始問市. 第二次世界大戰, 大量的行動電話技術被應用於軍事中.

◎ 1940年末, 貝爾實驗室提出 cellular 的觀念, 改變了行動電話必須構建高功率的發射機.

cellular 的特色: 頻率重複使用, 小功率發射機取代大功率發設機 (so cost 降低), 切割細胞, 開始有 handover 的概念 (真的可以通話中到處行走不被切斷).

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1G Cellular Telephony

¾ Advanced Mobile Phone Service (AMPS)

¾ Total Access Communication System (TACS)

¾ NTT (Nippon Telephone & Telegraph) , JTACS (1988), NTACS (1993)

¾ C450

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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

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, 歐洲電信標準協會)

¾ 陸上線路系統上建立類似 ISDN 的無線網路

¾ 將數據和個人隱私利用數位來傳輸

¾ 方便攜帶的SIM卡包含著顧客的身分資料

¾ GSM 系統是亞洲地區以及歐洲地區廣範被使用的 PCS 系統. 全球漫遊是GSM很大的優點

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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 (漫遊管理協定)

¾ Digital switch can provide many applications:

• Example: point-to-point short messaging, group addressing, call waiting, multiparty services

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EIA/TIA IS-136 Digital Cellular System (1/2)

¾ AMPS

¾ EIA/TIA: Electronic Industries Association and Telecommunication Industry Association : IS-54

¾ Digital AMPS (DAMPS), or North American TDMA (NA-TDMA), IS-54 → IS-136 (IS-54 is never used)

¾ The same spectrum used by AMPS

• 3 times of capacity of AMPS

¾ TDMA/FDD

¾ 來電顯示, 認證, 語音保密….. 容量為AMPS三倍

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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

EIA/TIA IS-95 Digital Cellular System (1/2)

¾ Qualcomm cdmaOne in USA since 1993(~1996)

¾ Korea in April, 1996.

PSTN PLMN

Switch

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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.

¾ IS-41 for core network

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Comparison of Cellular Systems

42 kps 1228.8 kps

48.6 kps 270.833 kps

Channel bit rate

11.2 kps 8 kps

7.95kps 13 kps

10 kps Speech rate

日美,韓,中國美

歐,台灣美

Region

FDMA TDMA FDMA

CDMA FDMA

TDMA FDMA

MAC

940-956 824-849

824-849 890-915

1710-1785 825-845

Uplink (MHz)

3 32

6 8

1 Channels

25kHz 1.25MHz

30kHz 200kHz

30kHz Carrier

FDD FDD

FDD Duplex

810-826 869-894

869-894 935-960

1805-1880 870-890

Downlink (MHz)

JDC IS-95

CDMA IS-136

GSM DCS1800 AMPS

System

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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

Low-Tier PCS

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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)

家用傳統無線電話

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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

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Characteristics of Cellular and Cordless Low-Tier PCS Technologies

Low(<=48Km/hr) Medium(<=96Km/hr)

High(<=257Km/hr) User Speed

Small/Zonal picocells Medium

micro and picocells Large/Continuous

macro cells Coverage Area

Low (5-10mW) Low (5-10mW)

High (100-800mW) Handset power

consumption

High (32Kbps) High (32Kbps)

Low (8-13Kbps) Speech Coding

Rate

Low (<=20ms) Low (<= 10ms)

High (<= 600ms) Delay or

Latency

Low Low

High Handset

Complexity

Small(50-100m) Medium(50-500 m)

Large(0.5-35 Km) Cell Size

CORDLESS LOW-TIER PCS

HIGH-TIER CELLULAR Systems

Third-Generation Wireless

System

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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)

• All IP mobile

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Third-Generation Wireless Systems

¾ 2.5G: GPRS and HSCSD

• Bridge 2G into 3G

¾ The new features for 3G includes

• High bit rates, QoS, Bit rates dependent on distance

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Third-Generation Wireless Systems

¾ 3G data rate requirement

• Vehicular: 144Kbps

• Pedestrian: 384Kbps

• Indoor: 2Mbps

3G Revolution

IS-95A

2 G 2.5G 3G

cdma2000 1x

GSM

EDGE IS-95B

GSM GPRS UMTS

IS-136 1xEV-DO

UMTS/

HSDPA Cdma2000 3xMC America

Europe

1xEV-DV

?

High Speed Downlink Packet Access

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Summary

¾ PCS Architecture

¾ Cellular Telephony

¾ Cordless Telephony and Low-Tier PCS

¾ Third-Generation Wireless Systems

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4G

ITU 於2003年6月批准的4G：

Vehicular : 100Mbps Motionless：1Gbps