A new Access Control Policy on the uplink of a DS-CDMA system

One of the key challenges in multi-services wireless cellular networks is the design of effective access control policy (ACP) algorithm, which not only has to ensure that the system guarantees potentially different QoS requirements from diverse applications, but also fully utilizes the scarce wireless bandwidth. On the uplink of a CDMA cellular network, successive interference cancellation (SIC) technique can be employed to reduce multiple access interference and improve system capacity. In this kind of system, K users correspond to K! decoding orders. Due to the constraint of received power, not all these decoding orders may be feasible. Examining the outputs of the ACP algorithm directly by the exhaustive search method (ESM) among all these K! possible decoding orders is a prohibitively time-consuming work, which leads to the impossible implementation of ACP algorithm. Carelessly accommodating a new session will be detrimental to all or some of other existing sessions in the system, even making the system collapsing. In this paper, we first address the issue of the searching algorithm of the Optimal Decoding Order (ODOS) in a DS-CDMA system with the constraint of the received power at the base station. Then, we develop a novel access control policy algorithm which employs the optimal decoding order, with the name of ODO-ACP algorithm. The proposed searching algorithm decoding order has the lowest computational complexity. Based on the output of ODOS algorithm, ODO-ACP could make fast decision on whether to accommodate a newly-arrival call request. Finally, we conduct computer simulations on the key system performance parameters, and the extensive simulation results validate the proposed algorithm.