  Not only is network coding essential to achieve the capacity of a
single-session multicast network, it can also help to improve the throughput of
wireless networks with multiple unicast sessions when overheard information is
available. Most previous research aimed at realizing such improvement by using
perfectly overheard information, while in practice, especially for wireless
networks, overheard information is often imperfect. To date, it is unclear
whether network coding should still be used in such situations with imperfect
overhearing. In this paper, a simple but ubiquitous wireless network model with
two unicast sessions is used to investigate this problem. From the diversity
and multiplexing tradeoff perspective, it is proved that even when overheard
information is imperfect, network coding can still help to improve the overall
system performance. This result implies that network coding should be used
actively regardless of the reception quality of overheard information.
