Interference Alignment with Limited Feedback

TL;DR

This paper demonstrates that in single-antenna interference networks with frequency-selective channels, limited feedback combined with interference alignment can achieve full spatial multiplexing gain, given sufficient feedback bits.

Contribution

It shows that naive interference alignment with vector quantization achieves full multiplexing gain under limited feedback constraints in frequency-selective interference networks.

Findings

Full spatial multiplexing gain of M/2 achieved with limited feedback

Feedback bits scale with M(L-1) log P for optimal performance

Interference alignment combined with vector quantization is effective

Abstract

We consider single-antenna interference networks where M sources, each with an average transmit power of P/M, communicate with M destinations over frequency-selective channels (with L taps each) and each destination has perfect knowledge of its channels from each of the sources. Assuming that there exist error-free non-interfering broadcast feedback links from each destination to all the nodes (i.e., sources and destinations) in the network, we show that naive interference alignment, in conjunction with vector quantization of the impulse response coefficients according to the scheme proposed in Mukkavilli et al., IEEE Trans. IT, 2003, achieves full spatial multiplexing gain of M/2, provided that the number of feedback bits broadcast by each destination is at least M(L-1) log P.