Optimal Strategies for Gaussian Fading Channels in Wireless Networks

1. Protocols of Gaussian Fading Channel Investigators: Yang Weng and Daniela Tuninetti, ECE; Prime Grant Support: NSF CAREER 0643954 Problem Statement and Motivation • In wireless peer-to-peer networks, the signal received by mobile users experience wide fluctuations due to fading and interference. • Orthogonalization techniques, such as TDMA, although leading to simple network architectures, can be very suboptimal in terms of achievable rates. • We propose communication strategies that improve network throughout over TDMA, especially at low SNR. Key Achievements and Future Goals Technical Approach • The received signal for user u is • where is the additive Gaussian noise, is the channel gain, and are the inputs. • Our goal is to maximize the sum of the achievable rates, or throughput, in the following two settings: • Ergodic capacity: perfect channel knowledge at the transmitters and mild delay constraints. • Outage capacity: unknown channel knowledge at the transmitters and strict delay constraints • Recently we determined a closed-form expression for the sum-rate of a two-user unfaded channels. • We are extending the result to fading channels. We design power control strategies that improve the sum-rate, especially at low SNR. • We plan to extend our results to large networks. Brief Bibliography: Y. Weng, D. Tuninetti On Gaussian Interference Channels wth mixed interference, ITA 2008, San Diego, CA, Jan 2008.