Multiple-Antenna Transmission With Limited Feedback in Device-to-Device Networks

We consider an overlay device-to-device network, where each multiple-antenna transmitter sends data to a designated single-antenna receiver by using maximum ratio transmission based on limited feedback, and their locations are modeled by a homogeneous Poisson point process. We obtain a lower bound on the optimum number of feedback bits that maximizes
net spectral efficiency
, capturing the overall system gain of using limited feedback. Our main finding is that the optimum number of feedback bits scales linearly with the number of transmit antennas and logarithmically with the channel coherence time and the inverse of the node density.