Toward Efficient 5G Transmission: SER Performance Analysis for Asynchronous Physical-Layer Network Coding

People's pursuit of higher quality communication has never ceased, which challenges the layout of 5G networks. Physical-layer network coding (PNC), as a key technology for 5G, supplies a powerful platform through leveraging the broadcast nature of wireless media. However, the symbol error rate (SER) of PNC is not well investigated, which would seriously influence user's quality of experience due to packet loss in wireless environment. In this paper, considering both phase and symbol misalignments, we perform analysis on SER of asynchronous PNC. By assuming part of information is known to the relay, and we derive the lower bound for SER. Afterward, through applying the concept of error vector and eliminating redundant terms, we derive the upper bound for SER. Both the lower and upper bounds are applicable to either multiuser detection-based network coding or belief propagation-based maximum a posteriori decoding. Finally, Monte Carlo simulation verifies our results and demonstrates that the bounds are relatively tight. The analytical results derived in this paper can facilitate future studies of practical and theoretical issues on PNC.