Code Division Multiple Access (CDMA) is widely used in current wireless communication systems such as IS-95 and third generation systems like WCDMA and cdma2000. The advantages of CDMA over other multiple access techniques include inherent multipath-diversity, spectrum efficiency and soft handoff. Nevertheless, its capacity is limited by multiple access interference. It is well-known that adaptive antenna arrays and interference cancellation can significantly reduce the multiple access interference and can greatly enhance the system performance. Nonetheless, the complexity of the system becomes a major concern....[ Read more ]

Code Division Multiple Access (CDMA) is widely used in current wireless communication systems such as IS-95 and third generation systems like WCDMA and cdma2000. The advantages of CDMA over other multiple access techniques include inherent multipath-diversity, spectrum efficiency and soft handoff. Nevertheless, its capacity is limited by multiple access interference. It is well-known that adaptive antenna arrays and interference cancellation can significantly reduce the multiple access interference and can greatly enhance the system performance. Nonetheless, the complexity of the system becomes a major concern.

In this thesis, we explore the combination of adaptive antennas and interference cancellation as a Joint-Space- Time Interference Cancellation receiver and investigate how the performance and complexity of the system are affected by different configurations of the adaptive antenna, the 2-D RAKE receiver and the interference canceller.

Our receiver is different from previous work in that adaptive antennas are used to obtain enhanced estimates of both the interference and the desired signals. These estimates are then used for interference cancellation. As a result, the reconstructed interference terms are more accurate and the system performance is significantly improved.

A possible disadvantage of our technique is increased receiver complexity and a solution to this is also addressed by pre-beamforming. With the use of an FFT beamformer, orthogonal beam patterns are formed and this facilitates the extraction of signal power from different angles. As a result, the total number of fingers used in the 2D-RAKE receiver can be reduced without severe degradation in the overall system performance.