Efficient broadcasting in tactical networks: Forwarding vs. network coding
Broadcasting (communicating information from one to all or many to all nodes in a network) is an important communication primitive. It is used as a building block in many MANET routing protocols, for example. In addition, broadcasting is a key primitive in tactical networks to support to deliver applications of all-informed voice, group push-to-talk, situational information sharing etc. Supporting one-to-all or all-to-all communication patterns in multihop wireless networks efficiently is therefore important. In this paper, we compare efficient broadcasting protocols based on packet forwarding and based on network-coding. Using a number of network scenarios, we derive lower bounds for the required number of packet retransmissions at the MAC layer to support broadcast with and without applying network coding techniques. We compare these lower bounds with each other, as well as with protocols proposed for each approach. More specifically, we use SMF and PDP as sample forwarding-based broadcast protocols, and a multisource random linear network coding protocol as a representative network coding approach. The results show that network coding has advantages over pure packet forwarding. However, none of the existing solutions comes close to approaching their respective lower bounds, leaving much room for new and improved protocols.