Power Control for User Cooperation

TL;DR

This paper derives optimal power control policies for a cooperative Gaussian multiple access channel, leading to simpler coding schemes and significant rate improvements by utilizing channel state information.

Contribution

It introduces optimal power allocation strategies that simplify coding schemes and convert non-concave problems into concave ones for cooperative multiple access channels.

Findings

Significant rate gains over existing systems

Simpler coding scheme compared to general feedback channels

Optimal policies leverage channel state information

Abstract

For a fading Gaussian multiple access channel with user cooperation, we obtain the optimal power allocation policies that maximize the rates achievable by block Markov superposition coding. The optimal policies result in a coding scheme that is simpler than the one for a general multiple access channel with generalized feedback. This simpler coding scheme also leads to the possibility of formulating an otherwise non-concave optimization problem as a concave one. Using the channel state information at the transmitters to adapt the powers, we demonstrate significant gains over the achievable rates for existing cooperative systems.