Reduced feedback and signaling schemes for sum-rate maximization in OFDMA systems
WCNC'09 Proceedings of the 2009 IEEE conference on Wireless Communications & Networking Conference
Capacity of a multiple-antenna fading channel with a quantized precoding matrix
IEEE Transactions on Information Theory
ICC'09 Proceedings of the 2009 IEEE international conference on Communications
Wideband fading channel capacity with training and partial feedback
IEEE Transactions on Information Theory
Packet error probability of a transmit beamforming system with imperfect feedback
IEEE Transactions on Signal Processing
Limited-rate channel state feedback for multicarrier block fading channels
IEEE Transactions on Information Theory
| Hi-index | 755.02 |
We study the capacity of multicarrier transmission through a slow frequency-selective fading channel with limited feedback, which specifies channel state information. Our results are asymptotic in the number of subchannels . We first assume independent and identically distributed (i.i.d.) subchannel gains, and show that, for a large class of fading distributions, a uniform power distribution over an optimized subset of subchannels, or on-off power allocation, gives the same asymptotic growth in capacity as optimal water filling, e.g., with Rayleigh fading. Furthermore, the growth in data rate can be achieved with a feedback rate as . If the number of active subchannels is bounded, the capacity grows only as with the feedback rate of . We then consider correlated subchannels modeled as a Markov process, and study the savings in feedback. Assuming a fixed ratio of coherence bandwidth to the total bandwidth, the ratio between minimum feedback rates with correlated and i.i.d. subchannels converges to zero with , e.g., as for Rayleigh-fading subchannels satisfying a first-order autoregressive process. We also show that adaptive modulation, or rate control schemes, in which the rate on each subchannel is selected from a quantized set, achieves the same asymptotic growth rates in capacity and required feedback. Finally, our results are extended to cellular uplink and downlink channel models.