Interference alignment for the K-user MIMO X network using time division multiple access

This paper investigates an interference alignment (IA) scheme suitable for a K-user multiple-input multiple-output (MIMO) wireless X network. The K-user MIMO X-network is a communication architecture where each transmitter, equipped with multiple antennas, has independent messages for each of the receivers, also equipped with multiple antennas. Earlier only 2 × N or M × 2 X networks were considered to be achievable. In this paper we remove this restriction by employing time division multiple access scheme. The proposed IA scheme allows each user to achieve a degree of freedom of KA/2K−1 a particular time slot, where A is the number of antennas at each transmitter and receiver. The capacity and bit error-rate (BER) performance of the proposed scheme is compared to that of another scheme recently proposed by Park and Ko. Simulation results are reported to show the BER performance for K-user (for a toy example, K is set equal to 3) and two-user X channel IA in case of transmission over flat-fading Rayleigh channels.