2. GSM
• Services : Voice & Data
• Speed : 9.6kbps (FR, HR, EFR)
• Modulation Scheme : GMSK
• Nodes : MSC, BSC, BTS, ME
• Air interfaces : Abis, A, Ater, Gb etc
• BW : 25 MHz with 200 KHz per carrier.
• Channels : BCCH, PCH, SDDCH, FACCH,
RACH, etc
• Access Method : TDMA
• Access Media : TDM
• Multipath Fading : Viterbi Equalizer.
• Coding scheme : CS1 (9.6kbps) To CS4
(21.4 kbps)
• BSC to BSC no direct connectivity
• AUC : Triplets (SRES, Ki, RAND)
WCDMA
• Services : Voice, data, Video
• Speed : 12.8kbps-4.5 kbps (AMR)
• Modulation scheme : QPSK
• Nodes: SMSC, MGW, RNC, RBS, UE
• Air interfaces : Iu-CS, Iu-PS, Uu etc
• BW : 60 MHz, with 5 MHz spread BW.
• Channels: CPICH, PRACH, DPDCH,
DPCCH etc
• Access Method : Spread Spectrum technique
with wide bandwidth.
• Access Media : ATM, IP, TDM
• Multipath fading : Rake reciever
• Coding Scheme : MCS1(8.8kbps) to MCS9
(59.2kbps)
• RNC to RNC connectivity via MGW.
• AUC : Vector-5 ( XRES, Ik, RAND, Ck,
AUTN)
• AUTN : MAC + SQN + Ak + AMF
3. • R99, R4, R5, R6 etc.
• Media gateway introduced in R99.
• IMS introduced in R4.
• HSDPA introduced in R5.
• EUL introduced in R6.
**** : Kindly refer 3GPP for further information.
4. GSM
• TCH (User payload)
• BCH
• AGCH
WCDMA
• DCH : DPDCH (user + L3) &
DPCCH (L1 ie Pilot bits, power
control).
• PCCPH (Broadcast Info)
• SCPCCH ( FACH + PCH)
CPICH, PCCPCH are continuous.
S-CCPCH, PICH, AICH, DDCCH, DPCCH are on demands.
5.
6. Note : AICH (Acquisition Indicator channel) uses 20 msec as it consist of 2 frames (means 30 slots).
7. • Open Loop : When UE is IDLE, No air interface link.
In GSM, RACH is sent with max. power.
In WCDMA, RACH is sent with min. power.
• Inner Loop (fast power control): When UE connected.
SIR) target< SIR)estimat-----Reduce Power
SIR) target> SIR)estimat-----Increase Power
Frequency of commanding for power control:
GSM : 2 times/sec ; CDMA : 800 times/sec ; WCDMA : 1500 times/sec.
• Outer loop (Slow power control) : RNC to control BLER.
BLER high------Quality low-----SIR) target increase.
BLER low------Quality high-----SIR) target reduce.
8. • Softer Handover: Intra site handover (within two sector of same site.
• Soft Hanover: Handover between two sites.
• Hard Handover:
Inter frequency (IF): WCDMA f1 and WCDMA f2.
Inter Radio Access technology (IRAT): WCDMA to GSM.
9. • Deployed in UE to avoid Multipath fading.
• At least 4 rake receiver and 1 search finger is deployed.
• Inner loop power control is used to overcome the fast fading.
• Maximum ratio Combiner (MRC) is employed as combining technique.
• Search Finger is used when performing handovers, scans neighbor node B
and estimated the channel parameters.
