On precoding for constant K-User MIMO Gaussian interference channel with finite constellation inputs

Ganesan, Abhinav ; Sundar Rajan, B. (2013) On precoding for constant K-User MIMO Gaussian interference channel with finite constellation inputs In: 2013 IEEE International Conference on Communications (ICC), 9-13 June 2013, Budapest, Hungary.

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Official URL: http://ieeexplore.ieee.org/document/6655012/

Related URL: http://dx.doi.org/10.1109/ICC.2013.6655012


This paper considers linear precoding for constant channel-coefficient K-User MIMO Gaussian Interference Channel (K-MIMO GIC) where each transmitter-i (Tx-i) requires to send di independent complex symbols per channel use that take values from fixed finite constellations with uniform distribution to receiver-i (Rx-i), for i = 1, 2, ..., K. The maximum rate achieved by Tx-i as the signal to noise ratio (SNR) tends to infinity, using any linear precoder, when the interference channel-coefficients are zero is termed as Constellation Constrained Saturation Capacity (CCSC) for Tx-i. In this paper, we derive a high SNR approximation for the rate achieved by Tx-i when interference is treated as noise, which is given by the mutual information between Tx-i and Rx-i, denoted by I[Xi;Yi] where, Xi denotes the symbols generated at Tx-i before precoding and Yi denotes the symbols received at the antennas of Rx-i. Based on this high SNR approximation, we derive a set of necessary and sufficient conditions on the precoders under which I[XiYi] tends to CCSC for Tx-i. Interestingly, the precoders that achieve interference alignment (IA) satisfy these necessary and sufficient conditions. However, finding precoders that achieve IA is known to be NP-hard in general whereas, the precoders that satisfy the derived necessary and sufficient conditions are easy to find for any given channel-coefficients. Further, we propose a gradient-ascent based algorithm to optimize the sum-rate achieved by precoding with finite constellation inputs and treating interference as noise. Simulation study for a 3-MIMO GIC with di = 1, for all i, equipped with two antennas at each node and QPSK inputs shows an improvement of 1.07 bits/sec/Hz in the ergodic sum-rate using the precoders obtained from the proposed algorithm over the precoders that achieve IA, at SNR = -2 dB.

Item Type:Conference or Workshop Item (Paper)
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ID Code:110150
Deposited On:08 Dec 2017 10:19
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