Optimal feedback allocation algorithms for multi-user uplink
Allerton'09 Proceedings of the 47th annual Allerton conference on Communication, control, and computing
Subchannel allocation in relay-enhanced OFDMA downlink with imperfect feedback
GLOBECOM'09 Proceedings of the 28th IEEE conference on Global telecommunications
On optimal feedback allocation in multichannel wireless downlinks
Proceedings of the eleventh ACM international symposium on Mobile ad hoc networking and computing
Optimization of training and feedback overhead for beamforming over block fading channels
IEEE Transactions on Information Theory
Limited-rate channel state feedback for multicarrier block fading channels
IEEE Transactions on Information Theory
Computer Networks: The International Journal of Computer and Telecommunications Networking
On distributed scheduling with heterogeneously delayed network-state information
Queueing Systems: Theory and Applications
Approaching throughput optimality with limited feedback in multichannel wireless downlink networks
IEEE/ACM Transactions on Networking (TON)
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In a downlink orthogonal frequency division multiple access (OFDMA) system, optimally allocating sub-channels across mobile users can require excessive feedback of channel state information (CSI). We consider an OFDMA model in which the feedback overhead is explicitly taken into account, given a fixed feedback rate and finite coherence time. The tradeoff between feedback rate and sum capacity is studied for two limited feedback schemes: a sequential scheme in which the users send compressed feedback bits over consecutive time slots, and a contention scheme in which users send their feedback via a random access protocol. For both schemes each feedback bit indicates a request for a group containing multiple subchannels. We show that the sum capacity for both schemes with optimized sub-channel groups grows linearly with the number of sub-channels N, and that the associated constant increases as the log of the normalized feedback rate measured in bits per coherence time per sub-channel. We also compare the asymptotic (large N) performance of the two limited feedback schemes as a function of the feedback rate and load (users per sub-channel). The sequential scheme performs best with moderate to large feedback rates, or small loads, whereas the contention scheme performs best with small feedback rates or large loads.