The existing physical-layer network coding(PNC) can be grouped into three generic schemes,which are XOR-based PNC,superposition-based PNC,and denoising-and-forward(DNFbased) PNC.Generally speaking,DNF-based PNC has better performance of rate pair region compared with the other two schemes when the transmission is symmetric.When the transmission is asymmetric,its performance is degraded severely.However,superposition-based PNC does not have that limitation even if its rate pair region performance is inferior...