Dynamic code assignment algorithm for CDMA with smart antenna system

This paper describes an optimal dynamic code assignment algorithm. This algorithm can be used to maximize the total number of users in a combined CDMA-SDMA multiple access system under minimum quality of service (QoS) and under limited number of available spreading codes L. A single cell adopts a combined CDMA-SDMA system as the air interface, and accommodates an arbitrary number of users K distributed randomly within the cell. The probability of blocking was calculated through simulations to evaluate the system performance under different number of users and available spreading codes. The result shows that the system performance is significantly improved using the proposed algorithm. Additionally, the total number of users can be significantly increased by a small increase in the number of available spreading codes. Finally, the proposed assignment algorithm enhances the code reuse ratio and therefore increases the code efficiency.