Providing quality of service for critical nodes in ad-hoc networks

As wireless ad-hoc networks consist of mobile nodes interconnected with no fixed infrastructure, they are highly appealing for communications in battlefields and disaster recovery areas where critical quality of service (QoS) transmissions are continuously required. Although the IEEE 802.11 MAC protocol is the standard for wireless LANs, this protocol was not designed for multihop networks where the well-known hidden and exposed terminal problems become more frequent. This work examines the impact of the presence of critical QoS nodes in an ad-hoc network. It uses both the interference aware capability at the MAC layer along with QoS control and takes advantage of spatial transmit diversity in multiple-input multiple-output (MIMO) channels. This allows servicing critical QoS nodes with a high efficiency without deteriorating fairness in the service of non-critical nodes.