Hierarchal Grouping with Adaptive Power Tuning in ZigBee Wireless Sensor Networks

Designing wireless sensor networks should meet appropriate parameters such as quality of service (QoS) defined by different users. The variable physical conditions of the environment, processing and transmission power limitations and limited communication capabilities are the most important obstacles that influence QoS parameters such as throughput, delay, reliability and network lifetime. The most important problems that directly have destructive effects on these parameters are hidden and exposed node problems. These problems extremely decrease throughput and increase delay and power consumption in the network. This paper proposes a new and efficient method to decrease the mentioned problems that relies on clustering, grouping and subgrouping strategy. Then different transmission powers are allocated to different nodes depending on their hierarchy level to communicate in their active time slots to decrease power consumption. This mechanism has been simulated by OPNET on IEEE802.15.4/Zigbee.