In this paper, an efficient radio resource allocation scheme for OFDMA systems is proposed, which follows two steps to take care of real-time traffic characterized with multi-level delay constraints. Urgent packets, those with imminent deadlines, are released first in step 1. After that the remaining channel resources are managed in such a way that overall throughput is maximized at Step 2. In this work, 2-dimensional diversity over multiple sub-bands and multiple users are jointly considered. The proposed scheme is compared with existing schemes designed for real-time traffic such as Exponential Scheduling (EXP) scheme, Modified Largest Weighted Delay First (M-LWDF) scheme, and Round robin scheme in terms of the packet discard probability and throughput. Numerical results show that the proposed scheme performs much better than the aforementioned ones in terms of the packet discard probability, while slightly better in terms of throughput.

This paper identifies a ripple effect problem (REP) that spreads interference to neighbors and proposes a novel channel localization mechanism to decrease the REP in a Wi-Fi system. The proposed mechanism has less blocking probability when compared to a random channel allocation mechanism and also has increased channel reusability. The proposed mechanism in simulation yields less channels BEm as the number of users and Tused increase.

In this paper, we propose a scheme of frequency sub-band allocation to obtain maximum throughput in an orthogonal frequency division multiple access (OFDMA) system where each user has a finite number of packets to transmit, which are generated from packet calls with arbitrary size and arbitrary arrival rate. The proposed scheme is evaluated in terms of throughput and user fairness in comparison with the proportional fairness (PF) scheme and the Greedy scheme under the finite queue length condition. Numerical results show that the proposed scheme is superior to the Greedy scheme in terms of both throughput and fairness for finite queue length.

In this paper, we mathematically derive a matrix-form solution named resource allocation matrix (RAM) for sub-band allocation in an orthogonal frequency division multiple access (OFDMA) system. The proposed scheme is designed to enhance throughput under a strict user fairness condition such that every user has an equal number of sub-bands per frame. The RAM designates the most preferable sub-band for every user. The proposed scheme is evaluated in terms of throughput and user fairness by comparison with the proportional fairness (PF) scheme and greedy scheme. Numerical results show that the proposed scheme has overwhelming superiority to other schemes in terms of fairness and tight competitive in terms of throughput.