Outage probability analysis of cooperative transmission protocols without and with network coding
Dereje Hailemariam Woldegebreal, Stefan Valentin, Holger Karl · 2007
In wireless networks, cooperative transmission is used as a means to combat channel fading. In this system, a source and a relay transmit each others' messages to a common destination using either amplify-and-forward or decode-and-forward strategies; the protocols in cooperative transmission can also broadly be categorized as static and adaptive. The idea in a network-coding-based cooperative transmission protocol is to allow the source and relay to combine messages by a network coding operation; a modulo-2 sum operation implements this network coding. In this work, the performance of various decode-and-forward-based cooperative transmission protocols without and with additional network coding is investigated. Outage probability is used as a measure of performance, and results for symmetrical source-relay and source/relay-destination channels are presented; also a source-relay-channels-based comparison is made. Based on these outage results, network-coding-based protocols are found to be suitable when the source-relay channels are unreliable; when the source-relay channels are good, protocols without network coding perform better. Moreover, to improve the performance of static protocols, we have introduced a sequence of decoding at the destination, and the corresponding outage results show that these protocols can achieve full diversity.