Existing code update protocols for reprogramming nodes in a sensor network are either unsuitable or inefficient when used in a mobile environment. The prohibitive factor of uncertainty about a node’s location due to their continuous movement coupled with the obvious constraint of a node’s limited resources, pose daunting challenges to the design of an effective code dissemination protocol for mobile sensor networks. In this work, we have designed an energy efficient, multi-chip reprogramming protocol for mobile sensor networks. Without making any assumptions on the location of nodes, this protocol uses the LQI and RSSI measurements of received packets to estimate link qualities and relative distances with neighbors in order to select the best node for code exchange. The protocol is based on a probabilistic broadcast paradigm with the mobile nodes smoothly modifying their advertisement transmission rates based on the dynamic changes in network density, thereby saving valuable energy. Contrary to previous protocols, this protocol downloads pages regardless of their order, thus, exploiting the mobility of the nodes and facilitating a fast transfer of the code.

 

The protocol has been implemented on a testbed of SunSPOTs. The SunSPOTs are the new sensor devices designed at SunLabs which are programmable in Java. It does not have an operating system and runs on a stripped down JVM called Squawk. The Netbeans IDE was used for this implementation.