Downlink SDMA With Limited Feedback in Interference-Limited Wireless Networks
The tremendous capacity gains promised by Space Division Multiple Access (SDMA) depend critically on the accuracy of the transmit channel state information. In the broadcast channel, even without any network interference, it is known that such gains collapse due to interstream interference if the feedback is delayed or low rate. In this paper, the authors investigate SDMA in the presence of interference from many other simultaneously active transmitters distributed randomly over the network. In particular they consider zero-forcing beamforming in a decentralized (ad hoc) network where each receiver provides feedback to its respective transmitter.