Limited feedback scheme for massive MIMO in mobile multiuser FDD systems

Massive multiple input multiple output is a promising technology to keep up with the explosive demand of wireless data traffic. The benefits of having a large number of antennas, however, depend on the availability of channel state information (CSI), especially at the transmitter. In frequency division duplex systems, this CSI has to be sent back via the uplink channel, hence incurring a large overhead and degrading the spectral efficiency. Mobility of the users and the large number of antennas exacerbate the problem with frequent tracking of the many timevarying CSI coefficients. This paper presents one approach to address this issue. By tracking only the principal components of the channel gain, and exploiting the wide-sense stationarity of the channel, the amount of required feedback can be reduced significantly. Simulation study shows that the proposed technique is able to achieve high sum-rate with good tracking capability using only limited feedback.