  We propose a simple yet effective wireless network coding and decoding
technique for a multiple unicast network. It utilizes spatial diversity through
cooperation between nodes which carry out distributed encoding operations
dictated by generator matrices of linear block codes. In order to exemplify the
technique, we make use of greedy codes over the binary field and show that the
arbitrary diversity orders can be flexibly assigned to nodes. Furthermore, we
present the optimal detection rule for the given model that accounts for
intermediate node errors and suggest a low-complexity network decoder using the
sum-product (SP) algorithm. The proposed SP detector exhibits near optimal
performance. We also show asymptotic superiority of network coding over a
method that utilizes the wireless channel in a repetitive manner without
network coding (NC) and give related rate-diversity trade-off curves. Finally,
we extend the given encoding method through selective encoding in order to
obtain extra coding gains.
