Analysis and extension of zigzag multiuser detection

Simultaneous transmissions from different nodes in a network can result in multiuser interference in which an intended receiver hears the overlapping combination of two or more transmissions. In the case where there are multiple observations with different time offsets of a collision (e.g., if the packet retransmissions also collide, or if there is a cooperating receiver with different propagation delays to the transmitters), zigzag decoding can be employed. In this paper, we analyze the performance of zigzag decoding for the case of two receiving nodes with two simultaneous transmitters in an additive white Gaussian noise (AWGN) channel. We also present a soft-decision version of zigzag decoding and show that it is the optimal MAP decision rule.