Group Node Contention Algorithm for Avoiding Continuous Collisions in LR-WPAN

In this paper, we proposed a group node contention algorithm for avoiding continuous collisions in LR-WPAN. The purpose of IEEE 802.15.4 is to achieve low speed, low cost and low power consumption. Recently, as applications of LR-WPAN have been extended, there is a high probability of collision as well. There are two types of collisions in LR-WPAN: i. contended collision: nodes are transmitting data concurrently at CCA starting point, ii. hidden node collision: collisions happened due to the hidden node problem. While the CSMA/CA mechanism can solve the contended collision, the hidden node collision can not be solved. Moreover, if the collision continuously occurs due to hidden node collision, network performance could be extremely decreased. Nowadays, a few papers have been proposed to address hidden node collision. One of the solutions is making use of PACK in WPAN which formed groups, but this algorithm wastes channel resource if continuous collisions frequently occur. In this paper, we assume that PAN has already formed groups, and by using pulse signal, coordinator allocates channel and orders, and then, nodes in the allocated group can compete with each other. Hence, contention nodes can be decreased significantly, channel wastage caused by collision can be reduced, and data transmission rate can be improved. On the whole, this algorithm can protect the network from disruption caused by frequent collisions and simulation result shows that the performance can be improved by using the algorithm.