The bandwidth adjustment in the last round (BA-LR) for WiMAX network

As a new technology for WLAN, the WiMAX network provides high speed Internet access and supports a variety of types of QoS. Service flows with different priorities are defined. The priority of real-time flow is higher than that of non real-time flow. The delay time is very crucial to realtime flow and every necessary strategy should be provided to increase its value. There are many studies for the scheduling of bandwidth in WiMAX. To make the performance as expected, most of them allocate bandwidth to queues in the unit of byte. Since the allocated bytes for each queue is allocated beforehand for each frame, the last sent data may contain only part of a packet in these protocols. As a result, this packet has to wait for at least one more frame to finish its transmission. In this case, the delay time of this packet may become unacceptable. In this paper, we propose an algorithm which is named the bandwidth adjustment in the last round protocol (BA-LR) can be put after any other scheduling algorithm in WiMAX. After the scheduling of other protocol, the queue will be checked. If the allocated bandwidth for real-time service flow does not fit into an integer number of packets, the allocated bandwidth will be adjusted to correct it. Since the total bandwidth of one frame may have been allocated, the adjusted bandwidth may have to be borrowed from other queue. Therefore, we proposed two schemes for this protocol in this paper. The first one is a protocol that the borrowed bandwidth is never returned. The other contains a mechanism that the borrowed bandwidth should be returned. Both will be simulated and compared. The results show the delay time of real-time flow will be improved with a little sacrifice of non-real-time flow.