Date Added: Dec 2011
Physical-layer Network Coding (PNC) makes use of the additive nature of the electromagnetic waves to apply network coding arithmetic at the physical layer. With PNC, the destructive effect of interference in wireless networks is eliminated and the capacity of networks can be boosted significantly. This paper addresses a key outstanding issue in PNC: synchronization among transmitting nodes. The authors first investigate the impact of imperfect synchronization in a 3-node network with a straightforward detection scheme. It is shown that with QPSK modulation, PNC on average still yields significantly higher capacity than straightforward network coding when there are synchronization errors.