New Scheduler with Call Admission Control (CAC) for IEEE 802.16 Fixed with Delay Bound Guarantee

摘要

The IEEE 802.16 Working Group is developing a standard for broadband wireless access in Metropolitan Area Networks (MAN) known as WiMAX. One of the features of the MAC layer, in this standard, is that it is designed to provide differentiated servicing for traffic with multimedia requirements. Based on these assumptions, and considering that the standard does not specify a scheduling algorithm, a new scheduler with call admission control was proposed based on Latency-Rate (LR) server theory and with system characteristics as specified by the system standard using the WirelessMAN-OFDM (Orthogonal Frequency Division Multiplexing) air interface. The proposed scheduling algorithm calculates the time frame (TF) in order to maximize the number of stations allocated in the system while managing the delay required for each user. Properties of this proposal have been investigated theoretically and through simulations. A set of simulations is presented with both Constant Bit Rate (CBR) and Variable Bit Rate (VBR) traffic, and performance comparisons are made between cases with different delays and different TFs. The results show that an upper bound on the delay can be achieved for a large range of network loads, with bandwidth optimization.