Performance and fairness enhancement in ZigBee networks

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ZigBee is a robust wireless communication standard which is based on physical and MAC layer on IEEE 802.15.4. ZigBee is also critically limited by the low data rate standard when there are many source nodes in the network. How to fairly and efficiently access the network and delivery the packets should be considered as one of the crucial issues. The simulation results illustrate that packet delivery ratio and delay are the most important measures for performance analysis in ZigBee. To obtain a better behavior of ZigBee network, we propose three methods which can significantly improve the packet delivery ratio and satisfy the requirements for fairness. Firstly, packet aggregation is introduced to ZigBee networks to aggregate data in an energy efficient manner so that network lifetime is enhanced. When there are too many nodes in the network, not all the nodes get the same chance to access the network and successfully transmit the packets. Three fairness metrics are introduced to evaluate the fairness among all the nodes. Intra-cluster and inter-cluster fairness are two proposed methods to enhance fairness based on packet aggregations. With intra-cluster fairness methods, cluster head should delay the packets and process the packets from the other node when the number of received packets from one source node is more than the average level. After intra-cluster fairness, different clusters still have fairness issue. Inter-cluster fairness should be designed to achieve absolute fairness among all the end devices. The simulations results show that our new methods could make the way of accessing the network and transmitting the packets efficient and fair as we have expected.