中文摘要：

为了改善物理层网络编码（PNC）在非对称双向中继通信系统中误比特率（BER）性能，提出了一种新的PNC方案，称为联合正交物理层网络编码（COPNC）．方案中2个源节点采用正交载波发送信息，中继节点对信息进行正交综合后广播到2个目的节点．理论分析与仿真结果表明，当双向中继通信系统信道条件非对称时，COPNC方案可以改善PNC的误比特率性能．特别是当2个上行信道的信噪比（SNR）不同时，COPNC方案的误比特率比PNC降低了约3dB．因此，COPNC特别适合应用于上行信道非对称的双向中继通信系统．

英文摘要：

To improve the bit error rate （BER） performance of physical-layer network coding （PNC） in asymmetric two-way relay communication systems, a new PNC scheme named combined orthogonal physical-layer network coding （COPNC） is proposed. In the scheme, the two source nodes employ orthogonal carriers ; then the relay node employs orthogonal combination and broadcasts the combined signal to the two destination nodes. Analytical and simulation results show that COPNC can provide better BER performance when the channel conditions in the systems are asymmetric. Especially when the two uplink channels have different signal to noise ratio （SNR）, BER of COPNC is lower about 3 dB than PNC. As a result, COPNC is very suitable to be used in two-way relaying communication systems with asymmetric uplink channels.