Salam Akoum, and Robert W. Heath, Jr.
To appear in IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP), Mar. 14-19, 2010.
Limited feedback beamforming improves link reliability with a small amount of feedback from the receiver to the transmitter. The performance of such a closed loop MIMO system is unknown in interference limited cellular environments, when the base stations have limited or no coordination. This paper establishes the degradation in throughput due to uncoordinated other cell interference and delay on the feedback channel. Under a Markov channel assumption, the paper shows that the throughput gain of cell edge users decays doubly exponentially as the delay increases. Numerical results illustrate how the decay rate decreases when the codebook size increases.
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