A new algorithm to improve mobile sensor node connectivity based on link quality indicator

In the standard protocol IEEE 802.15.4 for Wireless Sensor Network (WSN), the moving nodes experience difficulty in maintaining the connectivity within the network because of the low range and low power. The nodes easily lose their synchronization and connectivity in the beacon-enabled mode when they move from one coordinator to another. The connectivity maintenance introduced in the standard protocol does not satisfactorily maintain the smooth connectivity but it lengthens the inaccessibility time during the coordinator switching process. The mobile nodes consume more time and energy waiting for the lost beacon frames and performing the re-association process. This condition is becoming worse in the high speed nodes which operate within a long beacon interval mode. This paper presents a technique for the mobile sensor nodes to significantly improve their connectivity in wireless sensor networks without experiencing long inaccessibility times. We introduce a technique for the mobile nodes to predict the current link quality indicator (LQI) value of a beacon frame when they fail to receive any beacon frame from the coordinator. This LQI value is used to determine the mobile node´s position within the coordinator range. Based on this position, the mobile node decides either to straightaway start the association or wait for the next beacon frame. Simulation results indicate that our proposed protocol outperforms the standard protocol, increasing connectivity time and reducing inaccessibility time during the coordinator switching process.