The impact of convolutional coding on the uplink performance of UMTS air interface

Third generation of mobile communications systems (3G) integrate a wide variety of wireless services as multimedia services. Universal mobile telecommunications system (UMTS) is the main standard of 3G with WCDMA air interface. The WCDMA provides both error detection and error correction as channel coding scheme. The first one is provided by cyclic redundancy check (CRC) coding and the latter by a combination convolutional code with turbo decoding. For convolutional coding, both rate 1/2 and 1/3 are considered. This paper gives simulation observations of rate 1/3 convolutional coding effect on reverse link (uplink) for voice service and compares results with an uncoded system with a description of WCDMA technology and its channel coding scheme. A Rake combiner is implemented in receiver to compensate undesired channel effect and a Viterbi soft decision decoder performs decoding. FDD mode of WCDMA is selected as the operation mode of transmission. Conclusions are shown in bit error rate (BER) curves and no CRC coding or interleaving is used.