Delay-rate tradeoff in
ergodic interference alignment
Delay-rate tradeoff in ergodic interference alignment
O Johnson, M Aldridge, and R Piechocki
Preprint, 2012
Short version (PDF, 5 pages)
Extended version (PDF, 7 pages)
Abstract
Ergodic interference alignment, as introduced by Nazer et al (NGJV), is a technique that allows high-rate communication in n-user interference networks with fast fading. It works by splitting communication across a pair of fading matrices. However, it comes with the overhead of a long time delay until matchable matrices occur: the delay is qn2 for field size q.
In this paper, we outline two new families of schemes, called JAP and JAP-B, that reduce the expected delay, sometimes at the cost of a reduction in rate from the NGJV scheme. In particular, we give examples of good schemes for networks with few users, and show that in large n-user networks, the delay scales like qT, where T is quadratic in n for a constant per-user rate and T is constant for a constant sum-rate. We also show that half the single-user rate can be achieved while reducing NGJV's delay from qn2 to q(n-1)(n-2).
This paper is available as a short five-page conference version (PDF) and a longer extended version (PDF) with complete proofs and more detailed results.