Fair sub-carrier allocation in OFDMA and cognitive radio based IEEE 802.22 WRAN

In both orthogonal frequency division multiple access (OFDMA) and cognitive radio based IEEE 802.22 Wireless Regional Area Networks (WRAN), the problem of assigning the subcarriers to the users in a fairly manner is challenge. This paper investigates this issue and proposes a solution in the form of dynamic programming based sub-optimal algorithm. In this approach, the sub-carriers are initially allocated considering the equal power distribution. Then, a fair allocation of sub-carriers is achieved in such a way that comparatively equal data rate is obtained for all competing users and no user is completely starved; and the minimum desired sum rate is achieved in case a low channel gain user has been assigned the sub-carrier. Upon completion of the sub-channels allocation to all secondary users (SUs), the power allocation for each user is performed by means of the water-filling algorithm. Through simulations, our proposed scheme is shown to outperform a chosen benchmark scheme in terms of throughput and fairness, chosen as performance metrics.