Cellular and PCS Technical Issues

1
Cellular and PCS Technical Issues

• COMT 220

2
Overview

• Cell Layout
• Signaling
• Mobile Handset Operation

3
System Block Diagram
forward
Mobile
BTS
BSC
MTSO
PSTN
reverse
Data Bases
BTS Base Tranceiver Station BSC Base Station
Controller MTSO Mobile Telephone Switching Office
Radio Link
Voice Trunk
Data Trunk
4
Frequency Reuse Pattern
5
First Generation Standards

• AMPS - United States
• TACS - UK
• NTT - Japan
• NMT - Scandanavia
• MATS-E - France
• C-450 - Germany
• GSM - global

6
North American AMPS system

• 50MHz spectrum
• 30kHz per channel per direction
• 832 total full-duplex channels
• 4, 7, and 12 cell clusters used

7
AMPS Specifics

• 832 channels (2 frequencies per channel)
• Forward 869-894 MHz
• Reverse 824-849MHz
• Forward/Reverse Spacing 45MHz
• Adjacent Channel Spacing 30kHz
• 21 Control Channels per group
• Cell Sizes 2-20km

8
Mobile-Originated Call
Mobile
BTS
BSC
MTSO
PSTN
RCC
MIN, ESN, dialed no
validation
FCC
Ch No, SAT code, Power
SAT
FVC
SAT
RVC
FVC
Conversation
RVC
9
Call Handoff

• Base Stations monitor the signal strength
• If strength drops below hand-off level, all base
  stations are asked to look for the mobile
  strongest becomes new BS
• MTSO instructs the new base station to activate a
  voice channel to receive the handoff BS starts
  transmitting the Supervisory Audio Tone.

10
Call Handoff cont

• Current base station at MTSO command sends signal
  to mobile giving the new channel assignment.
• Mobile send a signaling tone burst, and tunes to
  the new channel.
• Previous base station clears the call path.

11
Mobile Handset

• ESN - Electronic Serial Number
• Programmable NAM (Number Assignment Module)
• Contains among other things
• System ID
• First control channel to scan
• A/B system selection
• MIN (Mobile Identification Number)

12
Mobile Identification Number

• MIN1 - Mobile System Id (3 digits)
• US Area Code
• International Mobil Carrier Identifcation
• MIN2 - Station Number
• US NXX and line number
• International international mobile number

13
Hand-Off
MS
MS
BS
BS
MTSO
14
Roaming
MTSO
Mobile
MTSO
Mobile
Mobile
Mobile
Mobile
Mobile
Mobile
Mobile
Mobile
15
Intersystem Hand-Off
MS
MS
BS
BS
MTSO
MTSO
16
The Shoe-Lace Effect
MS
BS
BS
BS
BS
BS
BS
BS
BS
MS
17
Multi-System Tandem
MS
MS
BS
BS
MTSO
MTSO
MTSO
MTSO
MTSO
18
Automatic Roaming
MS
BS
Request
MTSO
MTSO
Response
HLR
HLR
VLR
Current Location Temporary Directory Number
Billing Information Service Profile
19
The Trombone Effect
MS
BS
MTSO
MTSO
Fixed Station
20
Second Generation Systems

• COMT 220

21
Classes of Standards

• Analog Cellular
• FDMA - Frequency Division Multiple Access
• Digital Cellular
• FDMA
• TDMA - Time Division Multiple Access
• CDMA - Code Division Multiple Access

22
Access Methods
FDMA
TDMA
CDMA
23
Systems and Frequencies

• Advanced mobile phone service (AMPS)
• 824 to 849 MHz and 869 to 894
• Digital-advanced mobile phone service (D-AMPS)
• 824 to 849 MHz and 869 to 894
• Global system for mobile communications (GSM)
• 450 MHz, 890 to 960 MHz, 1.8 GHz, 1.9

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Systems cont.

• Personal communications service (PCS)
• 1.9 GHz
• Nextel and other specialized mobile radio (SMR)
• 816 MHz to 866 MHz
• Cellular digital packet data (CDPD)
• 824 to 894 MHz, 1.8 GHz to 1.9 GHz

25
3rd Generation Wireless Service

• COMT 220

26
3G Definition

• From the FCC Web Site
• 144 kbps (vehicular traffic) to 2 Mbps for indoor
  traffic
• Common billing and user profile services
• Bandwidth on demand
• Fixed and variable bit rates
• Multimedia store-and-forward messaging

27
Background

• ITU Specifications
• FPLMTS (future public land mobile
  telecommunication systems)
• IMT-2000
• Frequency bands identified at the 1992 and 200
  World Radio Conferences

28
Technical Specs

• Wideband CDMA (5MHz channel)
• CDMA2000 (1.25-15MHz channels)
• Based on TIA/EIA 95 B
• CMDA Time Division Duplex
• TDMA Single Carrier
• DECT (TDMA/FDMA)

29
Frequencies

• ITU Recommendations
• 1885-2025 MHz
• 2110-2200 MHz
• 806-960 MHz
• 1710-1885 MHz (1755-1850 studied by NTIA)
• 2500-2690 MHz (Studied by FCC)