Protocol Sequences for Asynchronous Multiple Access With Physical-Layer Network Coding

This letter proposes a new feedback-free solution that can put collisions to good use for decoding among asynchronous transmitters. Our key idea is to jointly exploit physical-layer network coding that allows a receiver to extract the bitwise XOR information out of time-overlapping signals, and a protocol-sequence-based scheme that allows each transmitter to deterministically determine which and when source packets contribute to the transmitted signal. In the application of group-based event detection, our design enables all source packets from asynchronous transmitters to be decoded within a quite short time duration. Simulation results show that our design, with low energy consumption, outperforms both conventional and state-of-the-art schemes in terms of the worst-case detecting delay.