BTS 1
BTS 3
BTS 2
Prepare by: Sanjay Gohel
1
GSM-900 System Specifications
Ø Frequency Range : 890 MHz to 915 MHz for Uplink
935 MHz to 960 MHz for Downlink. Ø Uses FDM / TDMA technology for Downlink / Uplink. Ø 124 Reusable Spot frequencies of 200 kHz bandwidth each. Ø Each Spot Frequency carries 8 Time slots for Traffic/Signalling. Ø Separate Logical Signalling & Traffic channels. Ø Compatible to ISDN & PSPDN.
Prepare by: Sanjay Gohel
2
Global G lobal System System for Mobile Mobile
Ø New rapidly expanding & successful technology. Ø Fully Digitized technology for better speech quality. Ø
Available in almost every part of the world.
Ø Fully compatible with existing Fixed Line Network. Ø
Single number operation with World wide Roaming.
Ø
Very well defined interfaces makes truly open system
Ø Encryption of user information i nformation Ø Available versions, GSM 900, 1800 & 1900
Prepare by: Sanjay Gohel
3
GSM Network Architecture OMC
SMSC BTS 1
AUC HLR
BTS 3
BSC
EIR
MSC VLR
NSS
VMSC
BTS 2 BSS Prepare by: Sanjay Gohel
PSTN N/W
4
Mobile Station (MS) Ø
Mobile Station consist of two units
Mobile Hand set
Subscriber Identity Module
Mobile Hand set is one of the most complicated GSM device. It provides user the access to the Network. Each handset has unique identity no. called IMEI.
SIM is a removable module goes into the mobile handset. Each SIM has unique number called International Mobile Subscriber Identity (IMSI). It has built in Micro-computer & memory into it. It contains the ROM of 6 to 16KB,RAM of 128 to 256 bytes and EEPROM of 3 to 8KB
Prepare by: Sanjay Gohel
5
Base Transceiver Station (BTS)
Ø
BTS has a set of Transceivers to talk to MS.
Ø
One BTS covers one or more than one cell.
Ø
Capacity of BTS depends on no of Transceivers.
Ø
BTS is connected to BSC via A’bis interface.
Ø
Transmission rate on A’bis is 2 Mbps (G.703).
Ø
Interface between MS & BTS is called Air I/f.
Ø
Transmission rate on Air interface is 13 Kbps.
Ø
BTS controls RF parameters of MS.
Ø
Each TRx has 8 TDMA channels channels to carry Voice Voice & signalling. signalling. Prepare by: Sanjay Gohel
Antenna Arrangement
BTS
6
Base Station Controller (BSC)
Ø
BSC controls several BTSs.
Ø
BSC manages channel allocation, & Handover of calls from one BTS to another BTS.
Ø
BSC is connected to MSC via A interface.
Ø
Transmission rate on A I/f is 2 Mbps (G.703).
Ø
Interface between BSC & BTS is called A’bis I/f.
Ø
BSC has database for all of its BTS’s parameters.
Ø
BSC provides path from MS to MSC.
Prepare by: Sanjay Gohel
BSC
7
Mobile Switching Centre (MSC)
Ø MSC is heart of the entire network connecting Fixed line network to
Mobile network. Ø
MSC manages all call related functions and Billing information.
Ø
MSC is connected to HLR & VLR for subscriber identification & routing incoming calls.
Ø
MSC capacity is in terms of no of subscribers.
Ø
MSC is connected to BSC at one end and Fixed Line network on other end.
Ø
MSC
Call Detail Record (CDR) is generated for each & every call in the MSC. Prepare by: Sanjay Gohel
8
Visiting Location Register (VLR) MSC VLR
Ø
Active Subscriber is registered in VLR.
Ø
It has temporary data base of all the active subscribers used for their call routing.
Ø
HLR validates subscriber before registration.
Ø
MSC ask VLR before routing incoming call.
Prepare by: Sanjay Gohel
9
Home Location Register (HLR) MSC HLR
Ø
All Subscribers data is stored in HLR.
Ø
It has permanent data base of all the registered subscribers.
Ø
HLR has series of numbers for all subscribers.
Prepare by: Sanjay Gohel
10
Authentication Centre (AUC) MSC HLR
AUC
Ø
Authentication is a process to verify the subscriber SIM.
Ø
Secret data & verification algorithm are stored in to the AUC.
Ø
AUC & HLR combined to authenticate the subscribers.
Ø
Subscriber authentication authentication can be done on every call, if required.
Prepare by: Sanjay Gohel
11
Equipment Identity Register (EIR) MSC EIR
Ø
All subscriber's mobile handset data is stored in EIR.
Ø
MSC asks mobile to send it IMEI & then checks it with data available in EIR.
Ø
EIR has different classification for mobile handsets like, White list, Grey list & Black list.
Ø
According to category the MS can make calls or can be stopped from making calls. Prepare by: Sanjay Gohel
12
Operation & Maintenance Centre (OMC) OMC
Ø
All the network elements are connected to OMC.
Ø
OMC monitors health of all network elements & carry out maintenance operation, if required.
Ø
OMC link to BTSs are via parent BSC.
Ø
OMC keeps records of all the faults occurred.
Ø
OMC can also do Traffic analysis.
Ø
OMC may prepares MIS Report for the network.
Prepare by: Sanjay Gohel
13
VMSC & SMSC MSC VMSC
SMSC
Ø
Voice Mail Service Centre : To provide Voice Mail service.
Ø
It has database for all the VMS subscribers & also stores voice messages for them.
Ø
Short Message Service Centre : To provide text message service.
Ø
To send short messages from mobile to another mobile subscriber. subscriber. Messages can also be sent by Manual Terminal connected to SMSC. SMSC.
Prepare by: Sanjay Gohel
14
Calll Proce Cal Processi ssing ng in in GSM GSM … 1 Mobile Originated Call
BTS
BSC
MSC
PSTN N/W
Ø
Mobile originated calls goes to BTS first & then to BSC.
Ø
BSC forwards this call to MSC.
Ø
MSC does authentication & call routing as per dialed digits.
Ø
If it the call to another mobile subscriber then the process for that call is same as Mobile Terminated Call as shown in next slide. Prepare by: Sanjay Gohel
15
Calll Proce Cal Processi ssing ng in in GSM GSM … 2 Mobile Terminated Call
BTS
BSC
MSC
PSTN N/W
Ø
Mobile terminated calls comes to MSC first, where HLR/VLR inquiry is carried out and as per information the MS is paged in suitable BSC.
Ø
BSC forwards this page to all children BTS where actual paging paging is done.
Ø
After BTS gets response from Mobile it allocates channel for this call.
Ø
After end of the call BTS informs BSC & MSC. Prepare by: Sanjay Gohel
16
Road Map of Mobile Data Communications 2G
3G
2.5G
3G
T E C
EDGE
H N
GPRS
O L
HSCSD
O G
9.6 Kb/s
Y 1999
-
2000 -
2001
- 2002
TIME Prepare by: Sanjay Gohel
17
Next Generation Services Requirements GSM Mobile service started in India with 2nd Generation service Capabilities, which supports voice & low speed circuit switched data. To support ever increasing demand of the customers many more advanced services are getting developed on GSM or other digital mobile platforms. A few of them are listed below : ü High Speed Packet Switched Data Connectivity ü Multimedia applications ü High Speed Remote Corporate LAN Access ü Web Browsing, E-mail, fax, wireless imaging ü Video Telephoney and TV broadcasting ü Blue Tooth Services Prepare by: Sanjay Gohel
18
Present Mobile Services & Technology GSM (Phase 2) SERVICES : u Voice Services u FAX & Data Services upto 9.6 Kbps , Short Message services
Limitations : Only circuit switching is possible, Spectral Efficiency is low Data Rate is limited to 9.6 Kbps
HSCSD (GSM Phase 2+) SERVICES : Ø Normal Data rate enhanced upto 57.6 Kbps Ø Typical applications :
Internet on mobile, Mobile LAN, Wireless real time Applications, File Transfer Limitations : Only circuit switching is possible, Spectral Efficiency is low Prepare by: Sanjay Gohel
19
Efficient Spectrum Utilization in GPRS One time slot statically assigned
Time slot dynamically assigned
8
GPRS
7
l l e C n i e g a s u e c r u o c s e R
6
5
4
3
Circuit Switched Traffic
2
1
Time Prepare by: Sanjay Gohel
20
Next Generation Services & Technology …1 GPRS SERVICES : Offer Data services upto 170 Kbps u Optimized protocol for packet switched data. u Typical application : Internet on mobile, File transfer, Wireless LAN, Remote control & Monitoring of Real time application, etc. ~ Good Spectral Spectral Efficiency Efficiency & Low Delay u
EDGE SERVICES : Ø Ø Ø Ø
Offer Data services upto 400 Kbps. Voice over Packet switched network. Supports IP based application. Typical application : Internet on mobile, Mobile LAN, Video Phone, Wireless real time Applications, File Transfer ~ High Spectral Efficiency & Higher Data rates Prepare by: Sanjay Gohel
21
Next Generation Services & Technology …2 3G (UMTS) SERVICES : u u u
Offer Data services upto 2 Mbps Voice over Packet switched IP based network. It can offer data rates as per requirements from 64 Kbps to 2 Mbps in rural or urban environment.
u Typical application : Speech Speech (symm (symmetri etric) c) - teleconfer teleconferenci encing ng & voice voice mail mail Message (asymmetric) - SMS, E-mail, etc. Switched data (symmetric) (symmetric) - low speed LAN, LAN, Internet, etc. Medium multimedia (asymmetric) - E-commerce, LAN, Internet, public messaging, etc. High multimedia multimedia (asymmetric) (asymmetric) - Video clips, clips, on-line shopping, shopping, fast LAN & Internet High interactive interactive multimedia (asymmetric) - Video Telephony, Video conferencing
~ Good Spectral Spectral Efficiency Efficiency & Low Delay, Delay, ~ Complete mobility to the user. Prepare by: Sanjay Gohel
22
Next Generation Services & Technology …3 The following is the comparison of Present & Next Generation Services.
Parameter M o d u l a t io n Bit Rate C h a n n e l B an d w i d t h Pulse shaping Modulation type
G SM
EDGE
Ga u s si a n MS K 2 7 0. 8 3 3 K b p s 200 KHz Gaussian prefilter, BT = 0.3 Non-linear, Constant envelope
3π /8-8PSK 812.4 99 Kb p s 200 KHz Linearized GMSK pulse Linear
The next generations will offer more services on the Mobile Terminals. However at the same time it requires more spectrum for its effective implementation & to support subscriber growth. Prepare by: Sanjay Gohel
23
Prepare by: Sanjay Gohel
24
