When Does Network Coding Benefit Store-Carry-and-Forwarding Networks in Practice?

For large content delivery in store-carry-and-forwarding networks, we study how and when the message delivery delay of the basic epidemic routing (ER) is improved with the introduction of message coding at the source (source coding: SC) and/or at the intermediate relay nodes (network coding: NC). A scenario is examined where a large file is divided into a number of messages and delivered from a stationary source node to a stationary destination in different islands being relayed by cars and ferry boats. In our scenario with limited network resources for exchanging and storing messages, message coding is expected to help ER but not in a straight-forward manner. Through quantitative and controllable evaluation by realistic simulations, we showed that ER+SC+NC is better than ER+SC when the communication link quality is good (e.g., with high wireless signal strength and low car moving velocity), but also that it is not always true as the link quality worsens.