PIM-WSN: Efficient multicast for IPv6 wireless sensor networks

We present PIM-WSN, a protocol independent multicast (PIM) protocol tailored for IPv6 wireless sensor networks (WSNs). Existing solutions for multicast in WSNs are limited because they either support multicast only from a single source node (usually the root node) or they limit the multicast group size to constrain memory usage. Our design allows any node to be a mulitcast source with an unlimited number of subscribers. We constrain the memory usage by approximating multicast group membership using a fixed sized Bloom filter. The efficiency of the protocol degrades as the false positive rate of the Bloom filter increases; however, correct operation is always maintained. Using detailed simulations we show that PIM-WSN achieves 1) high packet delivery rate (over 97%), 2) low latency per hop (less than 5 ms), and 3) lower radio utilization than all other comparable protocols (by more than 50%). Using a ten-hop testbed of TelosB motes we have verified our implementation of PIM-WSN for TinyOS 2.× with the Blip IPv6 networking stack which uses only 5,978 bytes of ROM and 235 bytes of RAM.