Near Optimal Update-Broadcast of Data Sets

We consider the problem of efficiently broadcasting incremental updates to multiple terminals that contain outdated (and possibly different) initial copies of the data. This situation occurs, for example, with the broadcast of Short Messaging Service [SMS] or Multimedia Messaging Service [MMS] cellphone messages to various clients whose phones are sometimes unavailable. We propose an efficient protocol for effecting such broadcast based on a novel combination of recent work on rate less coding and set reconciliation. Our approach is non-interactive, in that terminal nodes need not send any messages to the source, and stateless, in that the source need not know (or store) any information about the terminals. It also minimizes communication complexity and energy expenditure at the terminal nodes, at the expense of added computation. In support of our work, we provide several energy usage measurements on MICA2 sensor motes that clearly highlight the advantages of random linear decoding over wholesale data transfer.