Collaborative dynamic TDMA based code dissemination protocol for sensor networks

Sensor network reprogramming is a challenging problem and code dissemination is one of the important part in this subject. This paper proposes a novel TDMA-based code dissemination protocol which can greatly reduce the redundant message receptions and collisions in the dissemination process. We divide a program image into pages and page dissemination is in pipeline to reduce latency and achieve easy recovery. Since senders in the network frequently change their status, the static TDMA schedule is not efficient. On the other hand, the building of TDMA schedule before each page transmission is too complicated to use because of the high overhead. To overcome the problem, we propose a code dissemination protocol for nodes to learn local contending condition by overhearing normal messages or exchanging small amount of auxiliary messages when collision happens. Therefore the node can avoid receiving unwanted messages or making collisions with its neighbors. If no collision happens, auxiliary message exchange is unnecessary, otherwise the exchanged messages can help reduce future collisions. We implement our protocol in TinyOS-1.x with mica2 platform. The proposed protocol is simulated in TOSSIM and the simulation results show that our code dissemination protocol has better performance than Deluge.