Dynamic code allocation for integrated voice and multi‐priority data traffic in CDMA networks

Abstract

Abstract In the context of deriving schemes for efficient use of the spectrum by multi‐media users in direct‐sequence code‐division multiple‐access (DS/CDMA) networks we describe in this paper an optimal policy for CDMA code allocation to voice and multi‐priority data traffic We consider CDMA networks with voice traffic and two types of data traffic: high priority data traffic with the same priority as voice traffic that requires real‐time delivery and lower priority data traffic that can tolerate delay and thus can be queued. A movable boundary policy in the CDMA code domain is used for the voice and high priority data, whereas a small number of CDMA codes are reserved for the lower priority data which also utilizes any CDMA codes left unused by the other two traffic types. The optimal policy is obtained by minimizing a cost function consisting of the weighted sum of the rejection rates of voice and high priority data traffic subject to performance requirements (bit error rates or BER) on all traffic types. The queueing delay of the lower priority data traffic is also evaluated. A semi‐Markov decision process (SMDP) with guaranteed BERs for voice and data traffic is used for formulating the dynamic code assignment problem. A value‐iteration algorithm is applied to this SMDP to derive the optimal policy.