Wireless Communication Overview

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Wireless Communication Overview
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Generic WCS (Wireless Communication System)
Base Station
Base Station
Switch
Handset
Handset
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Dimensions

• Carrier/Network Operator
• Spectrum, PSTN, Internet, /ISP, Tele Service
  Provider
• Protocols/Standards/Systems
• GSM, AMPS, DECT, PHS, Satellite, ...
• Network Elements
• MSC, BSC, BTS, HLR/VLR, IN Elements, ...
• Services/Applications/Service Platform
• Voice call, data call, add-on services, ...
• Handset/Terminals/Smart Phone/Wireless Info
  Appliance
• OS, User-Interface, Protocol suite
• Subscriber Behavior

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Essential Functions

• Initialization
• Register
• Bursty Data/Signaling Transmission
• Paging, channel assignment, control signaling,
  signaling data, ...
• Mobility
• Handoff, roaming

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Wireless Communication Challenges

• Resources
• Bandwidth
• Channel impairment/fading
• Utilization
• Mobility
• Handover, Roaming
• Location management
• User access behavior
• Services
• Security, Data, ...
• Terminal Equipment
• Energy

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Technology Trend
Analog Voice
Digital Voice
Wireless Multimedia
Narrow band
Wide band
Mobile Phone
Mobile Phone Wireless Data
Wireless Info Appliance
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High-Tier v.s. Low-Tier Systems

• High-Tier Systems
• Serving a highly mobile population by means of
  sophisticated high-power radios
• Larger cell diameter
• Higher transmitter power
• Low-Tier Systems
• Serving subscribers moving at walking speeds
• Smaller cell diameter
• Lower transmitter power

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A System View

• High-Tier Systems
• GSM, DAMPS, CDMA
• Satellite Systems
• Low-Tier Systems
• CT-2, DECT, PHS, PACS

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Existed System Study (1)

• GSM
• (Global System for Mobile Communications)

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Outline

• Overview
• Architecture
• Numbering Routing
• Essential Functions
• Air Interface
• Dual Band Network Study

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GSM Overview

• GSM
• Developed by European Community
• Following ISDN
• Classified as Tele services and Data services
• International roaming
• Radio transmission is based on TDMA (Time Divide
  Multiple Access)

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GSM Air Resource Allocation

• Spectrum
• Uplink Band
• 890 - 915 MHz
• Downlink
• 935-960 MHz
• Spacing
• Duplex spacing 45 MHz
• Channel spacing 200 KHz
• Total channel number 124
• Number of slots per channel

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GSM Network Components

• MSC Mobile Switching Center
• BSC Base Station Controller
• BTS Base Transceiver Station
• HLR/VLR Home Location Register/Visting Location
  Register
• SIM Card Subscriber Identity Module Card
• Handset
• Service Center

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GSM System Architecture
HLR/ VLR
UM
A
A-bis
SS7
MSC
BSC
X.25
BTS
OMC (Operation Maintenance Center)
Handset
Operation Terminal
Data Terminal
Radio sub-system
Mobile station
Network sub-system
PSTN
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SIM Card

• Subscriber Identity Module
• Contains
• phone number (MSISDN)
• international mobile subscriber identity (IMSI)
• status of SIM
• service code
• authentication key
• PIN (personal identification code)
• PUK (personal unlock code)

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Numbering

• Mobile Subscriber ISDN Number (MSISDN)
• Mapping to Mobile Station Roaming Number (MSRN)
  by HLR
• International Mobile Subscriber Identify (IMSI)
• Stored in SIM/HLR
• Temporary Mobile Subscriber Identity (TMSI)
• Assigned by VLR, Stored in VLR
• International Mobile Equipment Identity (IMEI)
• Unique ID to handset, used by air interface

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Routing

• Information resident in MS SIM
• IMSI, TMSI, IMEI, and misc. information
• Routing Information used by Network
• MSISDN, MSRN

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Location Information Hierarchy

• Location Area Hierarchy

HLR
VLR
VLR
MSC1
MSC2
HLR Home Location Register VLR Visitor Location
Register MSC Mobile Switching Center LA
Location Area MS Mobile Station
LA1
LA2
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Location Information

• Determines subscriber current location
• Inform network when subscriber enters a new cell
• Have to trade-off between paging and location
  update traffic in system planning
• Location info contained in
• Mobile country code, mobile network code,
  location area code, cell ID
• Location information is the major burden for
  network

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GSM Essential Functions

• Registration/Location Updating
• Establishing Communication Link
• Handover
• Roaming

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Registration/Location Updating

• Inform system the new location of a MS when it
  changes Location Area (LA)
• MS continuously measures signal strength to
  choose the best radio base station
• The mobile station tunes to a new base station
  with better signal strength

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Establish Communication Link

• Handset request available channel from BTS
• BTS forward the request to BSC
• BSC chooses an available channel and inform BTS
  to activate the channel
• Information the BSC channel assignment message
  carries
• a reference number
• information about allocated channel (type,
  frequency, time slot, )
• the initial transmission power level to be used
  by the handset

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Handover

• The process of changing cells during a call is
  called handover in GSM terminology.
• The measurements to choose the best target cell
  are performed by MSs and BTSs.
• The measurements from the MS and the BTS are
  processed in the BSC. This evaluation process is
  called locating.

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Roaming

• A subscriber moves from the service area of
  his/her home service company(or network) to
  another operating company(or network)

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Wireless Data
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Computing Communication
Wireless Information Devices
Laptop
PDA
Mobile Phone
Communicator
Smartphone
Computing
Communication
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Wireless Voice Data Dominate Wireline
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Typical Internet Service Requirements

• Long (or continuous) sessions
• Multiple overlay sessions
• High degree of burstiness
• Large span in QoS requirements

Fundamentally difference from voice telephony
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Challenges

• IP network
• Protocols
• New data services
• Generic service platform
• Information appliances (Handhelds, Palm devices,
  Smart phones, In-Car systems)

Lots of bandwidth
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Todays GSM Data Services

• SMS (Short Message Service)
• USSD (Unstructured Supplementary Service Data)
• HSCSD (High Speed Circuit Switched Data )
• GPRS (General Packet Radio Services)
• EDGE (Enhanced Data rates for GSM Evolution)

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Convergence GSM/IP Network

• H.323
• WAP

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H.323 Architecture
Visiting MS
Home Service System
PSTN
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WAP (Wireless Application Platform)
Filter
WAP Proxy
Wireless Markup Language
Web Server
Filter
WAP Proxy
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Future GSM
Internet (TCP/IP)
GPRSUMTS
Co-sited GSM UMTS Base Station Subsystem
GSM mobile
Network Subsystem (GSMUMTS)
SGSN
GGSN
SIM Card
MSC/HLR (GSMUMTS)
GSM/UMTS mobile
GSM Base Station
BSC (GSM)
SIM
HLR
MSC
UMTS mobile
Landline NW (PSTN/ISDN)
UMTS (IMT-2000) Base Station
BSC (UMTS)
IN service control point
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GSM Radio Steps to 3rd Generation
Introduction of 3rd generation radio 2001 -
2002 New multimedia services Mass market cost of
service (IMT-2000)
Development of Radio Technology
2000 More capacity when needed (GSM384)
1999 Internet-like IP packet services (GPRS)
1998 Landline-like circuit services (HSCSD)
1997 Basic GSM data at 9.6 kb/s
Evolution of GSM Platform
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Air Interface Protocols

• SS7
• Between PSTN and PLMN ( Public Land Mobile
  Network)
• X.25
• BSC and Operation centers
• A
• Between BSC and MSC
• A-bis
• Between BTS and BSC
• Um
• Radio interface between BTS and Handset

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Air Interface Messages

• RR Radio Resource Management Messages
• MM Mobility Management Messages
• CM Call Management Messages

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Air Interface--Channels
Full-rate TCH/F
Two-way
Traffic channels
half-rate TCH/H
Frequency correction FCCH
Synchronization SCH
Broadcast control BCCH
Base-to-mobile
Paging PCH
Signaling channel
Access grant AGCH
Random access RACH
Stand-alone dedicated control SDCCH
Slow associated control SACCH
Two-way
Fast associated control FACCH
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Dual Band Network
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Dual Band Network GSM 900 DCS 1800 Air
Interface
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GSM/DCS Network Differences

• DCS 1800 cells are generally coverage limited
• GSM 900 cells tend to be capacity limited
• Implying a need for more DCS 1800 cells to
  provide similar coverage to a comparable GSM 900

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Integrate GSM and DCS Networks

• Integrating 900 and 1800 networks by linking
  900/1800 cells to same BSC An Integrated dual
  band network
• Sharing BSC, MSC, and HLR
• Benefits
• Reuse existing resources
• Reuse spectrum means to enlarge the scalability
  of network and to improve the utilization of
  spectrum resource
• Simplify the handoff between networks
• Flexible and changeable infrastructure

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Integrated Dual Band Network
MSC
BSC
DCS BTS
DCS BTS
DCS BTS
GSM BTS
GSM BTS
GSM BTS