WCDMA provides voice, data and video services at speeds ranging from 12.8kbps to 4.5Mbps using QPSK modulation over a 5MHz bandwidth. It uses a spread spectrum technique with wide bandwidth and supports ATM, IP and TDM access media. WCDMA introduces nodes like RNC, RBS and uses interfaces like Iu-CS, Iu-PS and Uu. It employs a Rake receiver and supports softer and soft handovers between nodes.

1. WCDMA Overview

2. GSM Vs WCDMA 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. 3GPP Releases 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. Spreading and Dispreading

5. Spreading Factor and Data Symbol Rate

6. Carrier ARFCNDL Downlink Frequency (MHz) Uplink Frequency (MHz) ARFCNUL 10550 2110 1920 9600 10551 2110.2 1920.2 9601 10552 2110.4 1920.4 9602 10553 2110.6 1920.6 9603 10554 2110.8 1920.8 9604 10555 2111 1921 9605 10556 2111.2 1921.2 9606 10557 2111.4 1921.4 9607 10558 2111.6 1921.6 9608 10559 2111.8 1921.8 9609 10560 2112 1922 9610 10561 2112.2 1922.2 9611 1 10562 2112.4 1922.4 9612 10563 2112.6 1922.6 9613 10564 2112.8 1922.8 9614 10565 2113 1923 9615 10566 2113.2 1923.2 9616 10567 2113.4 1923.4 9617 10568 2113.6 1923.6 9618 10569 2113.8 1923.8 9619 10570 2114 1924 9620 10571 2114.2 1924.2 9621 10572 2114.4 1924.4 9622 10573 2114.6 1924.6 9623 10574 2114.8 1924.8 9624

7. GSM vs WCDMA 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.

8. Basic frame structure

9. Frames Structure DPCCH RACH DPDCH & DPCCH

10. Control Channels vs SF Note : AICH (Acquisition Indicator channel) uses 20 msec as it consist of 2 frames (means 30 slots).

11. Power Control 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.

12. Handover Mechanism 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.

13. Rake reciever 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.