Throughput enhancement in mobile wireless networks using cooperative communication

Abstract

With the growth of mobile devices and smart devices, the demand of high bandwidth in wireless networks is increasing. To increase the throughput, the IEEE 802.11 standard specifies multi-rate capability, and several rate adaptive MAC (Medium Access Control) protocols have been proposed for the usage of multi-rate capability. However, these solutions are insufficient to further improvement due to only increasing the direct link performance. Therefore, cooperative communication has been proposed to additionally improve network performance. In cooperative communication, packets are transmitted via a relay node at high data rate instead of being directly transmitted to a destination at low data rate. In this dissertation, we propose cooperative communication protocols for mobile wireless networks.

First, we present the MAC protocol, called ECCMAC (Enhanced Cooperative Communication MAC) based on RTS-CTS, which fully utilizes cooperative communication and network coding. With cooperation, ECCMAC transmits data by way of the relay node at higher rate than direct transmission rate. For bidirectional flows, ECCMAC exploits network coding to improve network throughput. We consider that wireless links have property such as asymmetric data rate in real wireless networks. Using theoretical analysis, simulation, and simulation with measured data, we shows that ECCMAC considerably enhances the network performance.

Second, we propose a new cooperative communication scheme using partition scheme for WLANs (Wireless Local Access Networks) based on the IEEE 802.11. In WLANs, frequent collisions and performance anomaly limit the benefits of cooperative communication and the performance of WLANs. To reduce collisions and resolve performance anomaly, we divide nodes into several partitions based on the data rate. In addition, we propose a cooperative communication scheme using a relay partition to improve the throughput of nodes with low data rates and to achieve robust cooper...