Delay constraints for multiple applications in wireless sensor networks

Sensors are capable of supporting multiple applications concurrently. Recent works reveal several possibilities of running multiple applications in a wireless sensor network. In this work, we introduce the compression factor to quantify the change of the message length due to the aggregations of application messages. Delay constraints are introduced for two communication paradigms in wireless sensor networks, 1) the routing-based paradigm where sinks are specified and the routing trees are built for the aggregation; 2) the random-gossiping paradigm where aggregations are done by sensor nodes randomly communicating with the neighbour sensor nodes without specifying the sinks. Optimization problems which minimize the total energy consumption in the network are proposed for the two communication paradigms with the corresponding delay constraints. An example of a wireless sensor network with three sensor nodes and two concurrently running applications is used to demonstrate the optimization problems. Simulation results shows how compression factors affect the energy consumption while the message length of the application is increasing.