Khurram Ali Rizvi

Common channel interference cancellation for a spread spectrum system

This paper has mainly focussed on evaluating the potential performance improvements that accrue from cancelling the common pilot channels interference in terms of bit error rate performance for downlink applications. The impact of different cancellation strategies - sequential (SIC) and parallel (PIC) - has been presented for various data rates and channel profiles. With the investigative analysis appertaining to the FDD element of the UTRAN specified by 3GPP, the performance of the interference cancellation unit is primarily based on the elimination of the cross-correlation of the spreading codes over time dispersive wireless conditions. With a sound channel estimate, the results are shown to achieve near interference free performance, highlighting the potentiality of these interference cancellation schemes. Their versatility and robustness against channel estimation errors is further demonstrated by a relative performance comparison for a diversified range of data rates, pilot-to-data power ratios and channel conditions.

Performance enhancement analysis for a DS-CDMA system

This paper has addressed the impact of different interference cancellation algorithms - sequential interference cancellation (SIC) and parallel interference cancellation (PIC) - for various data rates and channel profiles that mainly focuses on the evaluation of the performance improvements that accrue from cancelling the common pilot channels interference in terms of bit error rate performance for downlink applications of a CDMA system. With these advanced signal processing strategies pertaining to the frequency division duplexing (FDD) element of the UMTS terrestrial radio access network (UTRAN) specified by 3GPP, apriori knowledge of the cross-correlation properties of the spreading codes for interfering common signalling channels is utilised in reducing interference under time dispersive wireless channel conditions. Performance analysis, with its dependency on the quality of the channel estimate, emphasises the potentiality of these interference cancellation schemes and their robustness against channel estimation errors.