Multi-way communication

1. Multi-way communication Natasha Devroye, ECE Primary Grant Support: UIC-WISEST startup funds • Communication is its most general form is a multi-way problem rather than an aggregation of 1-way problems; messages travel --> as well as <-- • In a wireless network we can take advantage of the ``broadcast nature’’ of wireless communication to overhear messages transmitted by other nodes and combine information traveling in many directions • Our main goal is to improve spectral efficiency (higher bits/second/hertz) in wireless networks with multi-way information flows • As a first example we consider the bi-directional relay channel: nodes a and b exchange messages through the help of a relay node r • Communication is subject to a time-division duplex constraint: a node cannot Tx and Rx at the same time • We take an information theoretic approach and obtain inner and outer bounds on the capacity region for a number of different protocols and relaying schemes: • Relaying schemes: Compress-and-forward, Decode-and-forward, Amplify-and-forward • Temporal protocols: 2 phase, 3 phase and 4 phase protocols are devised and shown to be optimal under different channel conditions • Comprehensive treatment of the single relay bi-directional channel: inner and outer bounds are tight in certain regimes • Future work will extend to multiple sources, destinations, relays. We will also consider relays which have independent messages of their own to transmit (e.g. cognitive radios)