Compute-and-Forward: Harnessing Interference through Structured Codes

Abstract

Interference is usually viewed as an obstacle to communication in wireless networks. This paper proposes a new strategy, compute-and-forward, that exploits interference to obtain significantly higher rates between users in a network. The key idea is that relays should decode linear functions of transmitted messages according to their observed channel coefficients rather than ignoring the interference as noise. After decoding these linear equations, the relays simply send them towards the destinations, which given enough equations, can recover their desired messages. The underlying codes are based on nested lattices whose algebraic structure ensures that integer combinations of codewords can be decoded reliably. Encoders map messages from a finite field to a lattice and decoders recover equations of lattice points which are then mapped back to equations over the finite field. This scheme is applicable even if the transmitters lack channel state information.

IEEE Trans. Info Theory, to appear. 23 pages, 13 figures

References in corpus (6)

• Interference Alignment and the Degrees of Freedom for the K User Interference Channel
• An Algebraic Approach to Physical-Layer Network Coding
• Nested Lattice Codes for Gaussian Relay Networks with Interference
• Providing Secrecy With Structured Codes: Tools and Applications to Two-User Gaussian Channels
• Ergodic Interference Alignment
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Cited by in corpus (4)

• Robust Lattice Alignment for K-user MIMO Interference Channels with Imperfect Channel Knowledge
• Multilevel Coding Schemes for Compute-and-Forward
• List decoding for nested lattices and applications to relay channels
• Coarse Network Coding: A Simple Relay Strategy to Resolve Interference