Compressed Sensing Based Multi-User Millimeter Wave Systems: How Many Measurements Are Needed?


Ahmed Alkhateeb, Geert Leus, and Robert W. Heath, Jr.


to appear in Proc. of IEEE Int. Conf. on on Acoustics, Speech, and Signal Processing, Brisbane, AUS, April 19-24, 2015.


Millimeter wave (mmWave) systems will likely employ di- rectional beamforming with large antenna arrays at both the transmitters and receivers. Acquiring channel knowledge to design these beamformers, however, is challenging due to the large antenna arrays and small signal-to-noise ratio before beamforming. In this paper, we propose and evaluate a down- link system operation for multi-user mmWave systems based on compressed sensing channel estimation and conjugate analog beamforming. Adopting the achievable sum-rate as a performance metric, we show how many compressed sensing measurements are needed to approach the perfect channel knowledge performance. The results illustrate that the pro- posed algorithm requires an order of magnitude less training overhead compared with traditional lower-frequency solu- tions, while employing mmWave-suitable hardware. They also show that the number of measurements need to be opti- mized to handle the trade-off between the channel estimate quality and the training overhead.