Experimental Evaluation of Interference Alignment for Broadband WLAN Systems

TL;DR

This paper experimentally evaluates the performance of spatial Interference Alignment (IA) in indoor WLAN scenarios using IEEE 802.11a standards, demonstrating its practicality and effectiveness in real-world conditions.

Contribution

The study provides an experimental validation of IA decoding schemes in indoor WLANs, including asynchronous user scenarios and practical measurement considerations.

Findings

IA performs well in indoor WLANs with large channel coherence times.

Time-domain IA decoding is effective for asynchronous users.

Compared IA with traditional TDM schemes showing competitive performance.

Abstract

In this paper we present an experimental study on the performance of spatial Interference Alignment (IA) in indoor wireless local area network scenarios that use Orthogonal Frequency Division Multiplexing (OFDM) according to the physical-layer specifications of the IEEE 802.11a standard. Experiments have been carried out using a wireless network testbed capable of implementing a 3-user MIMO interference channel. We have implemented IA decoding schemes that can be designed according to distinct criteria (e.g. zero-forcing or MaxSINR). The measurement methodology has been validated considering practical issues like the number of OFDM training symbols used for channel estimation or feedback time. In case of asynchronous users, a time-domain IA decoding filter is also compared to its frequency-domain counterpart. We also evaluated the performance of IA from bit error rate measurement-based results in comparison to different time-division multiple access transmission schemes. The comparison includes single- and multiple-antenna systems transmitting over the dominant mode of the MIMO channel. Our results indicate that spatial IA is suitable for practical indoor scenarios in which wireless channels often exhibit relatively large coherence times.