Grade of Service and Quality of Service Provisioning in CDMA Cellular Networks

Abstract:- In code division multiple access (CDMA) systems, call admission control (CAC) must be designed to guarantee both grade of service (GoS) at the call level and quality of service (QoS) at the packet level. Basically, there are two types of CAC schemes for CDMA systems: number-based CAC (NCAC) and interference-based CAC (ICAC). Unlike some previous studies assuming that handoff arrival rate is independent of the new call arrival rate, the handoff call arrival rate is allowed to depend on the new call arrival rate and other system parameters. Furthermore, the distributions of both cell dwell times and call durations are assumed to be hyper-exponential distributions, which is more bursty than the often-used exponential distribution. To prioritize handoff calls over new calls, guard channels are reserved for handoff calls. The appropriate multi-dimensional Markov chain models and analytical methods are derived to compute the performance measures for the considered CAC schemes. The performance measures of interest are new call blocking probability, handoff failure probability, and weighted cost for GoS, and loss probability of the communication quality for QoS. The effects of the variances of cell dwell time and call duration and guard channels on GoS and QoS are studied. Key-Words:- CDMA, quality of service, grade of service, guard channels, call admission control