An Adaptive Ant Colony Channel-Aware Slot Assignment in OFDMA-Based Mobile WiMAX Networks

Radio resource allocation in WiMAX is the major functionality of radio resource management (RRM) to support the Quality of Service (QoS) based on radio transmission characteristics in wireless communication systems. To allocate the slots seemly is an important issue and is regarded as ＂Binary Integer Programming＂ (BIP) problem that is one of NP-hard problems. This paper proposes a novel dynamic ant colony slot assignment (DACSA) algorithm including construct solution, local search, pheromone update and termination. Our algorithm achieves highly efficient resource utilization and fairness on the basis of specific channel conditions while guaranteeing the QoS requirements. Additionally, we propose two schemes for DACSA algorithm in the construct solution phase, namely Scheme1 and Scheme2. The Scheme1 is the original scheme, that is, the scheme that DACSA allocates slots to the RT-VR MSs based on proportional fairness indexes until the bandwidth requirements are satisfied. In the Scheme2, the DACSA only allocates portion of remaining slots to RT-VR MSs at the step 2 of construct solution when minimum QoS requirement is met. Therefore, the system throughput can be improved if some slots with bad channel condition for the MS are allocated to other MSs to get better capacity. The proposed DACSA algorithm is compared with PA (proportional allocation) and RCS (rate-guaranteed competitive scheduling) in terms of the packet delay, jitter, dropping rate, throughput, waste rate and fairness.