The goal of the third generation of mobile communication systems is to seamlessly integrate a wide variety of communication services such as high speed data, video and multimedia traffic as well as voice signals. The technology combines a Wideband Code Division Multiple Access (WCDMA) air interface with fixed network of Global System for Mobile communication (GSM). The work in this thesis focuses on the simulation of turbo coding scheme in WCDMA. The simulation is carried out using MATLAB 6.5, where the data is transmitted in a frame-by-frame basis on using turbo coding. The transmitted signal is corrupted by Additive White Gaussian Noise (AWGN) at the front end of the receiver. A turbo decoder is employed at the receiver where two types of the turbo decoder are used: Maximum A Posteriori (Log- MAP) and Soft Output Viterbi Algorithm (SOVA). Simulation results are obtained in the form of Bit Error Rate (BER) performance over a range of Eb/N0. Three parameters clearly affect the performance: Number of iteration, frame size, and puncturing. It can be observed that the MAP algorithm performs better than the SOVA decoder, from the results shown in the three iterations with code rate 1/2 and Eb/N0 equal to 3, the maximum BER is reached 10-5 using MAP decoder, while it is 10-4 in SOVA. It is worth to mention here that the frame size is set to 2048.