Abstract
The capacity of a code division multiple access (CDMA) system is limited by multiple access interference (MAI) and the near-far effect. Interference suppression and power control provide solutions to these problems. In some previous works, interference suppression and power control are considered separately. In order to increase the system capacity of a CDMA system, it is better to have a joint consideration of these two issues. Ulukus and Yates proposed an iterative and distributed algorithm that is able to achieve this goal. It is shown that this approach can converge to a minimum power solution where all users satisfy their own quality of service requirement; besides, the corresponding filter coefficients also converges to the minimum mean-squared error (MMSE) solution. Recently, Wang et al. have developed a strategy to reduce the high computational complexity involved in the algorithm proposed by Ulukus and Yates. The reduction of computational complexity comes from the use of an adaptive algorithm instead of the instantaneous MMSE approach for interference suppression. In this thesis, we further analyze the adaptive approach proposed by Wang et al and propose an improved scheme for power control with interference suppression. As compared to the approach by Wang et al., the proposed one achieves better performance (in terms of both convergence speed and power consumption) with no significant increase in complexity. Computation simulations are given to demonstrate the effectiveness of the newly proposed approach.