When analog meets digital: Source-Encoded Physical-Layer Network Coding

Abstract

We revisit Physical-Layer Network Coding (PLNC) in order to integrate this interference management technique in multi-hop wireless networks. We identify its strong coupling to the Two-Way Relay Channel (TWRC) as a main reason preventing it from becoming a staple in large networks. We introduce SE-PLNC (Source-Encoded PLNC), a new PLNC scheme that is traffic pattern independent and involves coordination only among one-hop neighbors, making PLNC significantly more practical to adopt in multi-hop wireless networks. To accomplish this, SE-PLNC introduces three innovations: it combines bit-level with physical-level network coding, it shifts most of the coding burden from the relay to the source of the PLNC scheme, and it leverages multi-path relaying opportunities available to a particular traffic flow. We evaluate SE-PLNC using proof-of-concept implementation on a Universal Software Radio Peripherals (USRP) testbed, theoretical analysis, and simulations. Testbed experiments show its real-life feasibility over a wide range of different channel conditions. The theoretical analysis highlight the scalability of SE-PLNC and its efficiency in large ad-hoc networks while large-scale simulations show that SE-PLNC improves network throughput by over 30% compared to state-of-the-art PLNC schemes.