Research On Spatial Diversity Over Wireless Mesh Networks

With the development of wireless communication techniques on demand, Wireless Mesh Network (WMN) has been widely deployed, which can extend the range of network services. In Wireless Mesh Network, data packet is forwarded to destination node by multiple hops before it arrives at the destination or the gateway node. It has been noticed by former researches that conventional communication protocols in layers of the protocol stack cannot fully adapt to this new feature, which does not satisfy the requirement of users. So it is very necessary to modify these protocols to enhance the transmission performance in WMNs.Cooperative communication in WMN has got more attention recently. It enables single antenna nodes in a multi-user environment to share their antennas, makes data transmission include not only the traditional "point-to-point" transfer mode, but also "multipoint-to-point" and "point-to-multipoint" transfer mode. Under cooperative communication, it can have more senders or receivers. Therefore, how to make use of cooperative communication to improve system performance is important. Aiming to improve system performance in wireless Mesh network, we focus on spatial diversity.Firstly, the background and research status of WMNs are introduced. The cooperative communications technology and spatial diversity in WMNs are described briefly.Secondly, we introduce some impaction on system performance by improving spatial diversity. Improving the utilization of wireless channel can effectively improve the performance of the system. Most researches have focus on improving channel utilization by exploiting spatial diversity, which can always reuse the channel. Spatial diversity means the space can be reused and wireless channel always to be reused. Based on exploiting spatial diversity in Wireless Mesh Network, this thesis introduces a distributed slot assignment algorithm, which can exploit the spatial diversity for more concurrent transmissions, and improve system performance.Finally, based on exploiting wireless media's broadcasting characters and spatial diversity, this thesis considers a cooperative metric and route algorithm, which considers cooperative communication and channel interferences. This routing can make more senders cooperatively send packets to one receiver, which can improve spatial diversity and the whole network system performance.This thesis does some research on spatial diversity from the angle of Network layer and Mac layer. How to combine Network layer, Mac layer and Physical layer to exploit spatial diversity is a future topic.