Interference alignment in UMTS Long Term Evolution

In this paper the performance of interference alignment is evaluated for the downlink of 3GPP UMTS LTE via the Vienna LTE Link Level simulator. Interference alignment is compared to closed-loop spatial multiplexing, a non-cooperative communication scheme. In order to reduce the computational complexity of solving the interference alignment problem for each subcarrier separately, the same precoding and interference suppression matrices are used for disjoint subsets of subcarriers. The performance impairment in terms of average throughput reduction of this approach is analyzed numerically. Furthermore, the performance of interference alignment is investigated for realistic fast-fading channels employing outdated precoding and interference suppression matrices.