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In this paper, a joint channel-and-queue-aware relay selection and resource allocation scheme at the scheduling phase in an OFDMA downlink cellular network is proposed. The scheme can choose the best relay to cooperate and allocate subchannels and power for the source and the relay for the selected packet which can maximize the proposed utility function waiting in the base station. Under the premise...
This paper considers the problem of optimal subcarrier allocation in OFDMA systems to achieve the minimum outage probability while guaranteeing fairness. The optimal subcarrier allocation algorithm and the maximum frequency diversity gain are both analyzed through the maximum matching method based on the random bipartite graph theory. Accordingly, a surprising result is found, which shows that the...
OFDMA technology can significantly improve the transmission reliability and efficiency because of its inherent frequency diversity and frequency multiplexing. In our recent work [B.Bai,W.Chen, Z.Cao and K. B. Letaief (2009) ], we have derived the optimal diversity-multiplexing tradeoff for OFDMA systems under the assumption that each subcarrier occupies the entire coherence bandwidth. However in practical...
OFDMA is a potential technology that can flexibly allocate subcarriers while providing diversity gain to multiple users. In our recent work, we showed a surprising result that the maximum frequency diversity gain in OFDMA systems is equal to the number of independent subcarriers, i.e., the same as that in point-to-point OFDM systems despite of the fact that multiple users will share a common set of...
OFDMA technology can significant improve the transmission reliability in multi-user communication systems because of its inherent frequency diversity. In a recent work, we have derived a surprising result which demonstrates that OFDMA systems can achieve a frequency diversity gain which is equal to the total number of independent subcarriers. In this paper, we shall show that the frequency diversity...
OFDM can provide frequency diversity gain for point-to-point communications over frequency-selective slow fading channel. Recent works show that OFDM may also form a flexible and efficient multiple access method, which is often referred to OFDMA. However, the user outage probability and the optimal frequency diversity gain in OFDMA systems are not known. In this paper, random bipartite graph is used...
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