The Interplay between Massive MIMO and Underlaid D2D Networking


Xingqin Lin, Jeffrey G. Andrews, Robert W. Heath, Jr.


Submitted to IEEE Trans. Wireless Commun., September, 2014.


In a device-to-device (D2D) underlaid cellular network, the uplink spectrum is reused by the D2D transmissions, causing mutual interference with the ongoing cellular transmissions. Massive MIMO is appealing in such a context as the base station's (BS's) large antenna array can nearly null the D2D-to-BS interference. The multi-user transmission in massive MIMO, however, may lead to increased cellular-to-D2D interference. This paper studies the interplay between massive MIMO and underlaid D2D networking in a single cell setting. We investigate cellular and D2D spectral efficiency under both perfect and imperfect channel state information (CSI) at the receivers that employ partial zero-forcing. We find that cellular transmit power can be scaled down as $\Theta(1/M)$ and $\Theta(1/\sqrt{M})$ under perfect and imperfect CSI respectively, where $M$ is the number of BS antennas, while achieving non-vanishing cellular spectral efficiency. Compared to the case without D2D, there is a loss in cellular spectral efficiency due to D2D underlay. With perfect CSI, the loss can be completely overcome if the number of canceled D2D interfering signals is scaled with $M$ at an arbitrarily slow rate. In the non-asymptotic regime, simple analycal lower bounds are derived for both the cellular and D2D spectral efficiency.