EETS8306_Lecture5_NetworkArchitecture2perpage

Cellular/PCS Network Architecture

Lecture 5, Rev. B, Slide 1© 2001 A. Triggs SMU EETS 8306 Wireless, Cellular, & Personal Telecommunications - Fall 2001

Southern Methodist University

SMU EETS 8306 and NTU TC 751-N, Fall 2001Wireless, Cellular, & Personal Telecommunications

http://www.engr.smu.edu/~triggs/

Lecture 5: Cellular/PCS Network Architecture

Instructor: Alan Triggs, Ericsson [email protected]

(972) 583-3107



Overview

• Cellular/PCS network architecture

• Brief description of each node, from the mobileback to the core, including some vendor products– Mobile Station– Base Station and Base Station Controller– Mobile Switching Center– Home and Visitor Location Registers– Authentication Center and Equipment Identity Register– Operation and Maintenance & Network Operations Center– Messaging Center– Inter-Working Function/Unit

• Various vendor architectures• Moving forward (data and next generation)



Cellular/PCS Voice Network Architecture

(G) MSC

HLR VLR

EIR

PSTN

BSC

BSC

Network Subsystem

Base Station Subsystem (BSS)

OMC/NOC

BS

BS

BS

PSTN: Public Switched Telephone Network(G)MSC: (Gateway) Mobile Switching CenterOMC: Operation and Maintenance CenterNOC: Network Operations CenterEIR: Equipment Identity RegisterHLR: Home Location RegisterVLR: Visitor Location RegisterAuC: Authentication CenterBSC: Base Station ControllerBS: Base StationMXE: Messaging CenterIWF: Inter-Working Function

AuC

MXE

IWF



Mobile Station (MS)

• We often call them “phones” but they’rebecoming much more than that lately– “Station” or “Terminal” is more appropriate

MotorolaiDEN

Phone

Nokia8800

• GSM phones are uniquelydifferent from all others– GSM phones have a

Subscriber Identity Module(SIM) card which can easily beremoved from the phone. TheSIM card contains the userprofile (phone number, barring,PIN number, etc.). Moredetails in GSM lecture.

EricssonR380

Ericsson R520 GPRS Phone

i-mode Phone



Base Station (BS or BTS)

• Also known as Base TransceiverStation (BTS)– Particularly in GSM nomenclature

• Purpose is to modulate, amplify,filter, and transmit the downlinksignals (and perform the reverseon the uplink)– Some vendors perform speech and

channel coding in the base station, butmost do so further back in the core

– Macro BTSs typically have a maximumoutput power of 40-45 dBm (~10-32Watts) and support about 100 channels

Samsung CDMA BTS

Ericsson TDMA BTS



Micro and Pico BTSs Becoming Common

• Micro base stations have lower power andlower capacity– Typically 20-30 dBm supporting 8-20 channels– Purpose is to relieve capacity in hot spots– All features of the technology are typically available– Must look small and aesthetically pleasing

• Pico base stations are necessary for good indoorcoverage– Even smaller and more discrete than micro base stations– Typically 10-20 dBm supporting 8-20 channels– Beginning to approach a ‘cordless’ base station in terms of

size and power



Micro and Pico Base Stations

SamsungCDMAPico BTS

Nokia CDMA Pico BTS2 Ericsson GSM Micro BTSswith external antenna

NokiaCDMAMicroBTS



Base Station Controller (BSC)

• BSC manages the base stations overthe “A-bis” interface– The A-bis link can be copper, fiber, or microwave

• The BSC handles:– Handoffs– Cell rankings– Locating– Power control– Channel allocation– Frequency/code allocations– Coding (if not in the BTS)– Limited switching

• Some vendors have BSC functionality in the MSC

SamsungCDMA BSC

EricssonCDMA BSC



Mobile Switching Center (MSC)

• The MSC is the heart of thesystem, controlling theswitching and billing– Some MSCs have BSC functionality

integrated in to them

• A Gateway MSC (G-MSC)interfaces to the HLR, PSTN,other PLMNs, and othernetworks such as packet datanetworks

Lucent 5ESS-2000CDMA MSC



Home Location Register (HLR) andVisitor Location Register (VLR)

• The HLR is a permanent database which containseach user’s service profile, MIN, ESN, etc.– Also includes roaming status of the user

• The VLR is a temporary database for all users– The VLR includes all users currently located in the system,

including roamers and non-roamers

• The MSC updates the VLR with HLR information

• Each MSC has a VLR, which usually resides with theMSC and each G-MSC has a HLR, which usuallyresides with the G-MSC



Authentication Center (AuC) andEquipment Identity Register (EIR)

• The AuC (or AC) stores encryption algorithms & keys

• The AuC is linked to the HLR– If the MIN or IMSI from the MS doesn’t match the AuC, the AuC

will inform the HLR to block the call (thus preventing fraud)

• The EIR is a database which contains equipmentinformation for all mobiles (often housed with AuC)– Electronic Serial Number (ESN) or International Mobile

Equipment Identity number (IMEI)

• EIR prevents theft, unauthorized use, and faultymobiles from being used in the system– Stolen or faulty mobiles are “black-listed” in the EIR



Operation and Maintenance / NetworkOperations Center (OMC/NOC)

• A wireless network is usuallyoperated and maintained via aNetwork Operations Center (NOC) orNetwork Management Center (NMC)– Typically looks like a war room with many

large screens, CNN, the weather channel,clocks for all major cities, etc.

• The NOC manages/reports:– 24 hour O&M– Switch and BTS outages– Switch and BTS errors– Traffic statistics

Lucent O&M Center

WFI Network Operations Center



Message Center (MXE)

• The MXE handles all messaging in a wirelesssystem– Short Message Service (SMS)– Cell Broadcast (rarely used)– E-Mail– Voice Mail– Fax Mail

• MXE functionality can be integrated into the MSC

• Sometimes known by individual service names,such as Voice Mail System (VMS)



Inter-Working Function (IWF)

• Also known in GSM as “GSM Inter-Working Unit (GIWU)”

• IWF is a piece of transmission and protocoladaptation equipment– To enable an MSC to connect with other networks

(particularly data networks).– IWF typically buffers, filters, and converts data to a suitable

format

• Sometimes integrated within the MSC



Network Maps from Vendors

Nortel’s GSMNetwork Architecture




Nortel’sCDMANetworkArchitecture



Impact of Data Services on Existing Architectures

• GPRS network for GSM operators (being deployed today):

Gn

Gi (IP)

Gn

IPNetwork

IPNetwork

OtherPLMNOtherPLMNBackbone

NetworkBackbone

Network

A

BSC MSC/VLR(MAP)

MS

BTSAbis

HLR

SGSN: Serving GPRS Support NodeGGSN: Gateway GPRS Support Node

SGSN GGSN

GrGb GsGc

New hardware for GPRS

MS




HDR/1xRTT Network Architecture (from Qualcomm)



Mobile Internet Network Reference Model

Other Networks

Net

wo

rk M

anag

emen

t

Applications/Content

ContentServers

Backbone Network(IP, ATM, etc.)

Connectivity

GPRS Servers

Communication& Control

Encryption TelephonyServices

Authentication Messaging

Locating

Mobility

PDA MobileEnd-User Devices& Technologies

BluetoothLocating

Techniques

Radio Access(GSM, W-CDMA, etc.)

Radio Network



Reading Assignment

• GSM Switching, Services, & Protocols– 3. System Architecture and Addressing (P. 29-45)

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