Date Added: Nov 2011
A wireless relay network is composed of a Base Station (BS), a few Relay Stations (RSs) and a large number of Mobile Stations (MSs). The BS serves as a gateway connecting the network to external networks such as the Internet. A spanning tree rooted at the BS is formed for routing, in which all MSs are leaf nodes. If an MS is out of the transmission range of the BS, it can communicate with the BS via one or multiple RSs in a multi-hop manner. This kind of network architecture has been adopted by emerging wireless networking standards such as IEEE 802.16j. The IEEE 802.16j task group was formed to extend the scope of IEEE 802.16e to support Mobile Multi-hop Relay (MMR).