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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 Inc.alan.triggs@ericsson.com
(972) 583-3107
Cellular/PCS Network Architecture
Lecture 5, Rev. B, Slide 2© 2001 A. Triggs SMU EETS 8306 Wireless, Cellular, & Personal Telecommunications - Fall 2001
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 Network Architecture
Lecture 5, Rev. B, Slide 3© 2001 A. Triggs SMU EETS 8306 Wireless, Cellular, & Personal Telecommunications - Fall 2001
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
Cellular/PCS Network Architecture
Lecture 5, Rev. B, Slide 4© 2001 A. Triggs SMU EETS 8306 Wireless, Cellular, & Personal Telecommunications - Fall 2001
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
Cellular/PCS Network Architecture
Lecture 5, Rev. B, Slide 5© 2001 A. Triggs SMU EETS 8306 Wireless, Cellular, & Personal Telecommunications - Fall 2001
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
Cellular/PCS Network Architecture
Lecture 5, Rev. B, Slide 6© 2001 A. Triggs SMU EETS 8306 Wireless, Cellular, & Personal Telecommunications - Fall 2001
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
Cellular/PCS Network Architecture
Lecture 5, Rev. B, Slide 7© 2001 A. Triggs SMU EETS 8306 Wireless, Cellular, & Personal Telecommunications - Fall 2001
Micro and Pico Base Stations
SamsungCDMAPico BTS
Nokia CDMA Pico BTS2 Ericsson GSM Micro BTSswith external antenna
NokiaCDMAMicroBTS
Cellular/PCS Network Architecture
Lecture 5, Rev. B, Slide 8© 2001 A. Triggs SMU EETS 8306 Wireless, Cellular, & Personal Telecommunications - Fall 2001
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
Cellular/PCS Network Architecture
Lecture 5, Rev. B, Slide 9© 2001 A. Triggs SMU EETS 8306 Wireless, Cellular, & Personal Telecommunications - Fall 2001
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
Cellular/PCS Network Architecture
Lecture 5, Rev. B, Slide 10© 2001 A. Triggs SMU EETS 8306 Wireless, Cellular, & Personal Telecommunications - Fall 2001
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
Cellular/PCS Network Architecture
Lecture 5, Rev. B, Slide 11© 2001 A. Triggs SMU EETS 8306 Wireless, Cellular, & Personal Telecommunications - Fall 2001
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
Cellular/PCS Network Architecture
Lecture 5, Rev. B, Slide 12© 2001 A. Triggs SMU EETS 8306 Wireless, Cellular, & Personal Telecommunications - Fall 2001
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
Cellular/PCS Network Architecture
Lecture 5, Rev. B, Slide 13© 2001 A. Triggs SMU EETS 8306 Wireless, Cellular, & Personal Telecommunications - Fall 2001
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)
Cellular/PCS Network Architecture
Lecture 5, Rev. B, Slide 14© 2001 A. Triggs SMU EETS 8306 Wireless, Cellular, & Personal Telecommunications - Fall 2001
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
Cellular/PCS Network Architecture
Lecture 5, Rev. B, Slide 15© 2001 A. Triggs SMU EETS 8306 Wireless, Cellular, & Personal Telecommunications - Fall 2001
Network Maps from Vendors
Nortel’s GSMNetwork Architecture
Cellular/PCS Network Architecture
Lecture 5, Rev. B, Slide 16© 2001 A. Triggs SMU EETS 8306 Wireless, Cellular, & Personal Telecommunications - Fall 2001
Network Maps from Vendors
Nortel’sCDMANetworkArchitecture
Cellular/PCS Network Architecture
Lecture 5, Rev. B, Slide 17© 2001 A. Triggs SMU EETS 8306 Wireless, Cellular, & Personal Telecommunications - Fall 2001
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
Cellular/PCS Network Architecture
Lecture 5, Rev. B, Slide 18© 2001 A. Triggs SMU EETS 8306 Wireless, Cellular, & Personal Telecommunications - Fall 2001
Network Maps from Vendors
HDR/1xRTT Network Architecture (from Qualcomm)
Cellular/PCS Network Architecture
Lecture 5, Rev. B, Slide 19© 2001 A. Triggs SMU EETS 8306 Wireless, Cellular, & Personal Telecommunications - Fall 2001
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
Cellular/PCS Network Architecture
Lecture 5, Rev. B, Slide 20© 2001 A. Triggs SMU EETS 8306 Wireless, Cellular, & Personal Telecommunications - Fall 2001
Reading Assignment
• GSM Switching, Services, & Protocols– 3. System Architecture and Addressing (P. 29-45)
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