Network Coding with Two-Way Relaying: Achievable Rate Regions and Diversity-Multiplexing Tradeoffs

TL;DR

This paper analyzes the achievable rate regions and diversity-multiplexing tradeoffs of different network coding schemes in two-way relaying for wireless ad hoc networks, providing insights into their relative performance and stability.

Contribution

It characterizes the rate regions of TDMH, MLNC, and PLNC, compares their performance, and proposes an opportunistic scheduling algorithm for system stability.

Findings

PLNC outperforms TDMH and MLNC in rate regions.

Time sharing between TDMH and MLNC improves achievable rates.

The proposed scheduling algorithm stabilizes the system within Shannon rate regions.

Abstract

This paper addresses the fundamental characteristics of information exchange via multihop network coding over two-way relaying in a wireless ad hoc network. The end-to-end rate regions achieved by time-division multihop (TDMH), MAC-layer network coding (MLNC) and PHY-layer network coding (PLNC) are first characterized. It is shown that MLNC does not always achieve better rates than TDMH, time sharing between TDMH and MLNC is able to achieve a larger rate region, and PLNC dominates the rate regions achieved by TDMH and MLNC. An opportunistic scheduling algorithm for MLNC and PLNC is then proposed to stabilize the two-way relaying system for Poisson arrivals whenever the rate pair is within the Shannon rate regions of MLNC and PLNC. To understand the two-way transmission limits of multihop network coding, the sum-rate optimization with or without certain traffic pattern and the end-to-end diversity-multiplexing tradeoffs (DMTs) of two-way transmission over multiple relay nodes are also analyzed.