On enhancing the energy conservation by ATIM window in wireless sensor networks

ATIM (Ad hoc traffic Indication Message) window can be used effectively to enhance the potential energy savings at static sensors nodes during data dissemination in wireless sensor networks. Doze and awake are two states a sensor node may be in during ATIM window. We consider a traditional wireless sensor network system consisting of resource-rich static sink and resource-constrained multiple static sensor nodes forming square grids. Sink may be multi-hop away from the sensor nodes and collects the data from them through multi-hop query-response propagation via shortest path. We consider three kinds of sensor nodes: (1) Target node (2) Intermediate nodes forming the shortest path (3) Idle nodes. The target sensor node and the intermediate sensor nodes are in awake state during one complete query-response process and do not follow ATIM concept for that duration. Each idle sensor node in the grid is strictly bound with ATIM window and is in doze state for maximum time to conserve energy. The sleeping sensor node wakes up at regular interval of time to read the beacon messages. If the message comes from sink, sensor node immediately reads the header part of query packet to check whether it is the intermediate node or the target sensor. The target sensor node further reads the remaining part of query packet and responds back to the sink with data through intermediate sensor nodes forming the shorted path. Sink transfers the collected data to the control station directly.