Bandwidth allocation using the statistics of arrival (BACSOA): A scheduling algorithm for WiMAX network

Five types of service flows are defined in the standard of IEEE 802.16. Each service flow has its own type of quality of service (QoS) requirement. Some scheduling algorithm is needed to satisfy the QoS requirement of each class. Traditional base station (BS) allocates bandwidth according to the request of user. However, the request may not equal to the real requirement in some situation. Thus, the assignment of bandwidth may be far from the real requirement. When the load is heavy, this may cause the time delay of some queue too large and create serious problem for real time traffic. Also, this may make the CAC mechanism denies any service although some old grants are never used completely. A method is proposed to solve this problem in this paper. In the beginning, we will use the traditional “request & grant” mechanism. However, we will assume some users may not estimate their request correctly and the system may not operate efficiently. To correct it, the mean μ and standard deviation σ of the arrival rate for ertPS and rtPS traffic will be estimated during the operation of system. The mean μ represents the average requirement and the standard deviation σ includes the possibly temporary requirement of this queue. Therefore, the grant will be replaced and μ + kσ will be used as the assignment of these traffics. Larger k gives real-time traffic more chance to send all its data in the queue. Comparing with traditional weighted round robin (WRR), we found this new protocol can provide higher throughput and lower delay when the request is not equal to the real requirement of the traffic.