Traffic-Variation-Aware Connection Admission Control Mechanism for Polling Services in IEEE 802.16 Systems

The bandwidth of the broadband wireless access is managed by a centralized base station (BS), which is achieved by a connection admission control (CAC) mechanism and a scheduler dynamically managing hundreds or thousands of ongoing connections persistently. The quality-of-service (QoS) services are also provided in the system for supporting more and more important multimedia services in wireless communications. There is a thorny problem, among these QoS types, of real-time polling service (rtPS) management when deciding the admission of new coming or scheduling ongoing connections due to their indeterminate characteristics of bandwidth requirement, e.g., variable bit rate (VBR) and delay constraint. This paper uses the characteristics of traffic variations as a parameter to construct the CAC mechanism for managing the real-time VBR services. Simulation results show that the proposed CAC can low down the call blocking probability of both rtPS and nrtPS traffics compared with the results of IEEE 802.16 standard. It not only decreases the number of dropped serving PDUs but also increases the system utilization.