An Adaptive CSMA/TDMA Hybrid-Mac for Wireless Sensor Networks

A new approach for energy efficient sensor networks that maximizes the life of the sensor networks which maintaining desired quality of service attributes related to sensed data delivery is presented. The IEEE802.15.4 as a standard for low rate wireless personal area network (LR-WPAN) is an applicative choice for wireless sensor networks. Due to the advantages of this standard and its capabilities for more specification to wireless sensor networks, we were persuaded to resolve some of its proven weaknesses in such environments. The slotted CSMA/CA method utilized in beaconsenabled mode of 802.15.4 causes an unacceptable level of energy consumption in conditions like high loads. To overcome these issues, we adopted method the capability and flexibility provided by CSMA/CA makes it work at low contention and TDMA makes it work at high loads by taking advantage of a greedy algorithm for TDMA slot allocation. Using these techniques we obtained improved results such as reduced energy consumption, improved throughput and decreased end to end delay. The new ATDMA and routing algorithm's scale well and converge fast for large scale dynamic sensors as shown by our extensive results using the Network Simulator (NS2).