DIMADIMA

Wireless and Mobile Wireless and Mobile Network ArchitecturesNetwork Architectures

Chapter 1Chapter 1IntroductionIntroduction

Digital Media Lab.Digital Media Lab.Jin-woo BaeJin-woo Bae

DIMADIMA

ContentsContents

● OverviewOverview● PCS architecturePCS architecture● Cellular Telephony(high-tier digital cellular Cellular Telephony(high-tier digital cellular

systems)systems) Advanced Mobil Phone Service(AMPS) Global system for Mobil Communications(GSM) EIA/TIA IS-139 Digital Cellular System EIA/TIA IS-95 Digital Cellular System

● Cordless Telephony and Low-tier PCS (low-tier DCS)Cordless Telephony and Low-tier PCS (low-tier DCS) CT2, DECT, PHS, PACS, Unlicensed System

● Third-Generation Wireless SystemsThird-Generation Wireless Systems● SummarySummary

DIMADIMA

OverviewOverview● Personal communications services (PCS)Personal communications services (PCS)

Variety of wireless access & mobility services provided any time, any place, any form

● High-tier digital cellular systemsHigh-tier digital cellular systems Global System for Mobile Communication(GSM) Digital Advanced Mobile Phone Service(DAMPS)

IS-136 TDMA Based Personal Digital Cellular(PDC) IS-95 CDMA-based cdmaOne System

● Low-tier telecommunication systemsLow-tier telecommunication systems CT2, DECT, PACS, PHS……

● Wideband wireless systemsWideband wireless systems cdma2000, evolved from cdmaOne W-CDMA, proposed by Europe SCDMA, proposed by China/Europe

DIMADIMA

1.1 PCS Architecture1.1 PCS Architecture

● Two of the most popularTwo of the most popular Cellular telephony Cordless and low-tier PCS telephony

● consist of two partsconsist of two parts Radio Network

PCS mobile stations (MSs) base stations (BSs)

Wireline Transport Network PSTN mobile switching center (MSC)

Mobile Switching CenterMobile Switching Center

Base station controllerBase station controller

PSTNPSTN

Radio NetworkRadio Network

Mobility DBMobility DB

Base stationBase station

The basic PCS network architectureThe basic PCS network architecture

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1.2 cellular Telephony1.2 cellular Telephony

1.2.1 Advanced Mobile Phone Service (AMPS)1.2.1 Advanced Mobile Phone Service (AMPS) Developed during the 1970s(first analog cellular system) Service has been available since 1983 832 full-duplex(50MHz band, FDMA)

824~849MHz(R) / 869~894MHz (T) Different cluster frequency reuse

1.2.2 Global System for Mobile communications 1.2.2 Global System for Mobile communications (GSM)(GSM) Developed by CEPT and ETSI(European countries) Combines TDMA and FDMA 13kbps speech coding include most features a digital switch can provide IS-41

Point-to Point short messaging, group addressing, call waiting……

DIMADIMA

1.2 cellular Telephony(cont’)1.2 cellular Telephony(cont’)

1.2.3 EIA/TIA IS-136 Digital Cellular System1.2.3 EIA/TIA IS-136 Digital Cellular System DAMPS, ADC, NA-TDMA, IS-54 IS-136 (IS-54 revision C(Renamed)) capacity is around three times that AMPS

Speech coding rate : 7.95kbps(AMPS : 30Kbps)

1.2.4 EIA/TIA IS-95 Digital Cellular System1.2.4 EIA/TIA IS-95 Digital Cellular System Developed by Qualcomm Has been operating in the USA since 1996 Based on CDMA Bandwidth is 1.25MHz(narrow CDMA system) capacity is around ten times that AMPS

DIMADIMA

1.2 cellular Telephony(cont’)1.2 cellular Telephony(cont’)

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1.3 Cordless Telephony and Low-Tier PCS1.3 Cordless Telephony and Low-Tier PCS

1.3.1 Cordless Telephone, second Generation(CT2)1.3.1 Cordless Telephone, second Generation(CT2) CT2 was developed in Europe (since 1989) 40 FDMA channels with a 32-Kbps rate Maximum transmit power is 10mW

1.3.2 Digital European Cordless Telephone(DECT)1.3.2 Digital European Cordless Telephone(DECT) Spec were published in 1992 Using TDMA(time slot transfer) 12 voice channels per frequency carrier Dynamic channel allocation Wireless-PBX PSTN

DIMADIMA

1.3 Cordless Telephony and Low-Tier 1.3 Cordless Telephony and Low-Tier PCS(cont’)PCS(cont’)

1.3.3 Personal Handy Phone System (PHS)1.3.3 Personal Handy Phone System (PHS) Developed by RCR Using TDMA 77channels with 300KHz bandwidth 40ch for public systems, 37ch for home/office app Dynamic channel allocation

1.3.4 Personal Access Communications System (PACS)1.3.4 Personal Access Communications System (PACS) Developed by telcordia PACS is designed for wireless local loop

DIMADIMA

1.4 Third-Generation Wireless Systems1.4 Third-Generation Wireless Systems

● High speed, wireless Internet access, and wireless High speed, wireless Internet access, and wireless multimedia service multimedia service

● GPRS, EDGE ……GPRS, EDGE ……● Wideband CDMA, cdma2000 are majorWideband CDMA, cdma2000 are major

DIMADIMA

1.5 Summary1.5 Summary

systemsystem High-tier cellularHigh-tier cellular Low-tier pcsLow-tier pcs CordlessCordless

Cell sizeCell sizeLargeLarge

(0.4-22mi.)(0.4-22mi.)MediumMedium

(30-300ft.)(30-300ft.)SmallSmall

(30-60ft.)(30-60ft.)

User speedUser speedHighHigh

(≤160mph)(≤160mph)MediumMedium

(≤60mph)(≤60mph)LowLow

(≤30mph)(≤30mph)

Coverage areaCoverage area Large/continuous macroLarge/continuous macrocellscells

Medium micro and piMedium micro and picocellscocells

Small/zonal picocellSmall/zonal picocellss

Handset Handset complexitycomplexity HighHigh LowLow LowLow

Handset power Handset power consumptionconsumption

HighHigh

(100-800mW)(100-800mW)LowLow

(5-10mW)(5-10mW)LowLow(5-10 mW)(5-10 mW)

Speech coding rateSpeech coding rateLowLow

(8-13Kbps)(8-13Kbps)HighHigh

(32 Kbps)(32 Kbps)HighHigh

(32Kbps)(32Kbps)

Delay or latencyDelay or latencyHighHigh

(≤600ms)(≤600ms)LowLow

(≤10ms)(≤10ms)LowLow

(≤20ms)(≤20ms)

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Chapter 2Chapter 2Mobility ManagementMobility Management

DIMADIMA

OverviewOverview

MSC

Base Station

VLR

MSCVLR

Base Station

HLRVisitor Location

Register

Mobile Switching Center Home Location

Register

PSTN

• Handoff : when a Mobile user moves to another BS, Handoff : when a Mobile user moves to another BS, old BS disconnect & new BS conversation old BS disconnect & new BS conversation

• Roaming : When a Mobile user moves to another PCS System Roaming : When a Mobile user moves to another PCS System informed of current location of the user informed of current location of the user

DIMADIMA

2.1 Handoff2.1 Handoff

● MCHO (Mobile Controlled Handoff)MCHO (Mobile Controlled Handoff) MS 가 통화채널의 신호강도를 측정 , MS 가 handoff 여부 결정 DECT, PACS

● NCHO (Network Controlled Handoff)NCHO (Network Controlled Handoff) BS 가 통화채널의 신호강도를 측정 , MSC 가 handoff 여부 결정 CT-2, AMPS (analog cellular system 에서 사용하는 방식 )

● MAHO (Mobile Assisted Handoff)MAHO (Mobile Assisted Handoff) MS 가 통화채널의 신호강도를 측정하여 BS 에 전송 , MSC 가 handoff

여부 결정 IS-95 CDMA, GSM

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2.1.1 Inter-BS Handoff2.1.1 Inter-BS Handoff

MSC

Old BS New BS

MSC

Old BS New BS

MSC

Old BS New BS

MSC

Old BS New BS

x

(a) Step 1: MS 는 새로운 BS 상의 현재 비어있는 채널의 신호에 의해 잠시 통신을 중단하고 핸드오프 절차를 시작

(b) Step 2 : 신호 수신 후 , MSC 는 선택된 새로운 채널에게 암호화된 정보를 전송 , MS 에게 채널을 통해 새로운 통신로를 설정 . 스위치는 새로운 통신로와 이전통신로를 연결하며 MS 에게 이전채널에서부터 새로운 채널로 전환하게 알리는 역할을 한다

(c) Step 3 : 새로운 채널로의 전환을 후 , MS 는 망에게 신호를 보내고 새로운 채널을 이용하여 통신을 다시 시작 .

(d) Step 4 : 핸드오프 완료신호를 접수한 후 , 망은 이전채널로의 자원과 통신로를 삭제 .

DIMADIMA

2.1.1 Inter-BS Handoff(cont’)2.1.1 Inter-BS Handoff(cont’)

● Channel assignment schemesChannel assignment schemes Reserved channel scheme

Similar to the nonprioritized scheme Some channels in each BS are reserved for handoff calls

Queueing priority scheme Overlapped area(handoff area) New BS buffers the handoff request in a waiting queue

Subrating scheme Creates a new channel for a handoff call by sharing resources with an existi

ng call Divided into two channels at half the original rate

Call / handoff request

DIMADIMA

2.1.2 Intersystem Handoff2.1.2 Intersystem Handoff

MSCA

MSCB

PSTN

BS1 BS2

Base Stations

Trunk MSCA

MSCB

PSTN

BS1 BS2

Base StationsTrunk

(a) Before the handoff

(b) After the handoff

DIMADIMA

2.2 Roaming Management2.2 Roaming Management

● MS registration procedureMS registration procedure

NEWVLR

1 3

HLR OLDVLR

2 4

Visitor Location Register

Home Location Register : network database

Los Angeles, California New York City, New York

Morristown, New Jersey

DIMADIMA

2.2 Roaming Management(cont’)2.2 Roaming Management(cont’)

● Call delivery procedureCall delivery procedure

MSC

PSTN HLRVLR

3

1

1 122

3Routable Address

trunk(voice circuit)

DIMADIMA

2.3 Roaming Management under SS72.3 Roaming Management under SS7

● SS7 is a Common channel signaling(CCS) systemSS7 is a Common channel signaling(CCS) system CCS(Common Channel Signaling)

Provides control & management func. in the telephone network Consists of supervisory functions, addressing and call information provisioni

ng Uses a separate out-of-band signaling network to carry signaling messages

SS7(Singalling System No. 7) Signaling between a PCS network and the PSTN are achieved by SS7

network

DIMADIMA

2.3 Roaming Management under SS7(cont’)2.3 Roaming Management under SS7(cont’)

STPSTPSCP HLRSTPSTP

MSCSSP

SignalingLinks

Trunk

PSTNPCN (PCS Network)

(SCP)

SSP(Service Switching Point) Perform call processing

STP(Signaling Transfer Point) Relays SS7 messages

SCP(Service Control Point) Contains databases

DIMADIMA

2.3.1 Roaming Management under SS72.3.1 Roaming Management under SS7

● RegistrationRegistration

MSC1

PSTN

PSTN

PSTN

STP3STP3

STP4STP4

STP2STP2

SCP

(HLR4)

SCP

(VLR2)

SCP

(VLR1)

MSC2

12

2 3

4

5

GlobalTitle

Translation

deregistrationderegistration

reg. acknowledgementreg. acknowledgement

table-lookup table-lookup MIN-to-HLR MIN-to-HLR

MIN? (Mobile Identification Number)MIN? (Mobile Identification Number)

Registration queryRegistration query

DIMADIMA

2.3.1 Roaming Management under SS7(cont’)2.3.1 Roaming Management under SS7(cont’)

● Reduce the deregistration trafficReduce the deregistration traffic Implicit deregistration

Obsolete VLR records aren’t deleted until the database is full If the database is full, a record is deleted No deregistration messages

Periodic re-registration MS periodically reregisters to the VLR Only creates local message traffic between MSC and VLR No SS7 signaling message are generated if the VLR is co-located with the

MSC

DIMADIMA

2.3.1 Roaming Management under SS7(cont’)2.3.1 Roaming Management under SS7(cont’)

● Reduce the registration traffic (a pointer forwarding Reduce the registration traffic (a pointer forwarding scheme)scheme) Move operation (registration)

A pointer is created from

the old VLR to new VLR No registration to the HLR is required

Find operation (call delivery) After the find operation,

the HLR points directly to destination VLR

MSCSCP

(VLR)

MSCSCP

(VLR)

MSCSCP

(VLR)

SCP(VLR)

MSCSCP

(VLR)

MSCSCP

(VLR)

MSCSCP

(VLR)

SCP(VLR)

x

DIMADIMA

2.3.2 Call Delivery2.3.2 Call Delivery

● Call DeliveryCall Delivery Maintain the cache in the STP that performs GTTs

PSTN

PSTN

STP3STP3

STPSTP

STPSTP

SCP(HLR)

MSC

GlobalTitle

Translation

PSTN

STPSTP

MSCSCP

(VLR)

1 13

2

3

DIMADIMA

Roaming Management for CT2Roaming Management for CT2

● Basic Public CT2 System (One-Way Calling)Basic Public CT2 System (One-Way Calling) Did not support call delivery CT2 control system

Bear the responsibility for monitoring and billing Be connected indirectly to the BSs through the PSTN

Utilized the paging system to provide call delivery

PSTNswitch

switch switch

CT2 ControlSystem

BS BS

handset