Simulation of Third Generation CDMA Systems - Virginia Tech

channel model based on measurement and investigate the WCDMA performance underpractical mobile channel condition. We have shown that it is very simple to employ thesimulator to observe the performance of error correction coding. We implemented aconvolutional coding scheme for an uplink voice application of 9.6 kbps. It was observed thatchannel coding could significantly lower the required SNR for a particular BER.5.1 Future WorkThe simulator employs a simple rake receiver to exploit the gain arising from temporaldiversity. Spatial property of the multipath environment can be another source of diversity.Adaptive antennas are used at the receiver to take the advantage of this diversity gain. Thesimulator can be used to investigate the diversity gain of different adaptive algorithms.Space-Time rake receivers [21], [22] or 2-D rake receivers [23] have been proposed tocombine the temporal and spatial diversity at the receiver. Transmit diversity techniques[13], [14] at the downlink are gaining rapid popularity since they do not incur additionalhardware complexity at the mobile station. We are investigating various transmit diversityschemes and different 2- D rake receivers for the WCDMA system. The simulator wasmodified so that a large number of frames are transmitted rather than transmitting one frameat a time.Turbo coding has been specified for applications that require very low bit error rate.Turbo coding schemes can be incorporated to the simulator in the same way we employedconvolutional coding.The simulator can be further improved by using statistical channel models based onmeasured data. The improvement in system performance by using multi user detection andinterference cancellation can also be investigated.71