An approximation downlink bandwidth allocation scheme for IEEE 802.16 OFDMA system

Recently, Orthogonal Frequency Division Multiple Access (OFDMA) transmission technique is applied widely in wireless networks because of its high transmission capacity. The IEEE 802.16 standard has also adopted the OFDMA as its access technique. However, the problem of bandwidth resource allocation in time and frequency is essential for efficient utilization of OFDMA system. In this paper, we proposed an approximation resource allocation scheme to improve the downlink bandwidth utilization. In the resource allocation scheme, we sort the requests of users and allocate bandwidth based on dynamic programming strategy which can save the calculation result of subproblems to reduce the executive time of algorithm. In simulations, it is shown that our scheme outperforms the greedy algorithm in bandwidth utilization. Also, we compare our scheme with optimal allocation method, which is implemented by brute force with branch and bound algorithm. The results show that our method outperforms optimal allocation method by bandwidth utilization, stability, and execution time.