PALER: A Reliable Transport Protocol for Code Distribution in Large Sensor Networks

Re-tasking and remote programming of sensor networks is an essential functionality to make these networks practical and effective. As the availability of more capable sensor nodes increases and new functional implementations continue to be proposed, these large collections of wireless nodes will need the ability to update and upgrade the software packages they are running. Standard flooding mechanisms are too energy-costly and computationally expensive and they may interfere with the network´s current tasks. A reliable method for distributing new code or binary files to every node in a wireless sensor network is needed. This paper proposes a more effective method, called PALER (push aggressively with lazy error recovery), which builds upon the previously proposed PSFQ protocol [1], a reliable transport protocol which slowly paces the propagation of file segments, but uses an aggressive local recovery method to avoid packet implosion due to loss propagation. PALER uses a more aggressive pushing mechanism and reduces the recovery mechanism to a single inclusive NACK. Furthermore, PALER uses local neighbor information to reduce redundant transmissions. This paper studies this new protocol´s energy efficiency and shows that it scales well to higher densities and field sizes.