GPS-Free Host Approaching in Mobile Ad-Hoc Networks

In mobile ad-hoc networks (MANET), the location tracking techniques based received signal strength indicator (RSSI) has attracted significant research interest. Because MANET is a self-configuring infrastructure less network of mobile devices connected by wireless and can be effectively deployed during disaster recovery, it improves rescue efforts following a disaster. Most important, it can be used for the searching of survivors using the location tracking based on RSS measurement in consideration of the inadequate environment of GPS and a distance-estimation is effective method. However the RSS measurement is so vague, it is so difficult to use the searching by using only pure RSSI reading. The key points for the searching are the RSSI Calibration and the RSSI difference detection (RDD). The PLE is a key parameter in the distance-estimation based on RSS measurement and there is a weak point that must be required pre-measurement to estimate the PLE using access points or anchor nodes which are aware of the distance. The RDD is important to approach and there is a weak point to detect quite-variable caused by multipath fading in live network. This paper proposes the way of approaching the target station seen as survivor by means of the RSSI Calibration and RDD without pre-measurement. The weak points are solved by using moving distance in place of the known distance for the PLE estimation. Using the reset counter which keeps a moving direction until exceeding is an indication for changing the direction. We evaluated that it is possible to show the ability of approaching the target station based on the RSSI Calibration and reset counter using the RSSI readings and moving distance. Our results show that GPS-free host approaching in MANET performs effectively and this can enhance to approach survivors for rescue efforts.