cellular and pcs technical issues
DESCRIPTION
Cellular and PCS Technical Issues. COMT 220. Overview. Cell Layout Signaling Mobile Handset Operation. System Block Diagram. forward. Mobile. BTS. BSC. MTSO. PSTN. reverse. Data Bases. BTSBase Tranceiver Station BSCBase Station Controller MTSOMobile Telephone Switching Office. - PowerPoint PPT PresentationTRANSCRIPT
COMT 220
1
Cellular and PCS Technical Issues
COMT 220
COMT 220
2
Overview• Cell Layout• Signaling• Mobile Handset Operation
COMT 220
3
System Block Diagram
Mobile BTS BSC MTSO PSTN
Data Bases
forward
reverse
BTS Base Tranceiver StationBSC Base Station ControllerMTSOMobile Telephone Switching Office
Radio Link Voice TrunkData Trunk
COMT 220
4
Frequency Reuse Pattern
COMT 220
5
First Generation Standards• AMPS - United States• TACS - UK• NTT - Japan• NMT - Scandanavia• MATS-E - France• C-450 - Germany• GSM - global
COMT 220
6
North American AMPS system
• 50MHz spectrum• 30kHz per channel per direction• 832 total full-duplex channels• 4, 7, and 12 cell clusters used
COMT 220
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
COMT 220
8
Mobile-Originated CallMobile BTS BSC MTSO PSTN
RCC MIN, ESN, dialed novalidation
FCC Ch No, SAT code, Power
FVC SAT
RVC SATFVCRVC
Conversation
COMT 220
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.
COMT 220
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.
COMT 220
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)
COMT 220
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
COMT 220
13
Hand-Off
MTSO
BSBS
MSMS
COMT 220
14
Roaming
Mobile
MTSO
MobileMobile
Mobile
Mobile
MTSO
MobileMobile
Mobile
Mobile
COMT 220
15
Intersystem Hand-Off
MTSO
BSBS
MSMS
MTSO
COMT 220
16
The “Shoe-Lace” Effect
BSBS
BSBS
BSBS
BSBS
MS
MS
COMT 220
17
Multi-System Tandem
MTSO
BS BS
MS MS
MTSOMTSO MTSO MTSO
COMT 220
18
Automatic Roaming
MTSO
BS
MS
MTSO
HLR
HLR VLR
Request
Response
Billing InformationService Profile
Current LocationTemporary Directory Number
COMT 220
19
The “Trombone” Effect
MTSO
BS
MS
MTSO
Fixed Station
COMT 220
20
Second Generation SystemsCOMT 220
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
COMT 220
22
Access MethodsFr
eque
ncy
TimeFr
eque
ncy
TimeFr
eque
ncy
Time
FDMA
TDMA
CDMA
COMT 220
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
COMT 220
24
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
COMT 220
25
3rd Generation Wireless ServiceCOMT 220
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
COMT 220
27
Background• ITU Specifications
– FPLMTS (future public land mobile telecommunication systems)
– IMT-2000
• Frequency bands identified at the 1992 and 200 World Radio Conferences
COMT 220
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)
COMT 220
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)