A novel application-semantics based hybrid QOS MAC in wireless sensor networks

In this paper the nodes in a WSN are considered as the sinks dealing with different applications, which hieratically make up the network application. Ontology is used to semantically describe the application, so that nodes directly process and transmit application rather than data. Based on application semantics, a new hybrid application semantic MAC (AS-MAC) is put forward. Nodes send sub-tasks containing the semantics of sub-application and QoS parameters in a prioritized CSMA fashion to reply the cluster head´s task request, and a TDMA scheme with variable frame length is adopted to schedule the nodes selected by the cluster head according to their replies to carry out the sub-tasks to provide QoS guarantees. Because of the subtask negotiation during the selection of the nodes, the redundancy among data of the nodes could be eliminated efficiently, leading to better network performance. Simulation results demonstrate that AS-MAC achieves better performance in terms of energy consumption and delay than the popular MAC protocols such as ECR-MAC, ZMAC and S-MAC.