Construction of Instantly Decodable Network Codes for Semi-online Feedback Broadcast Transmission

Instantly decodable network coding (IDNC) is a class of network coding schemes with low coding complexities for wireless broadcast. Most studies of IDNC in the literature focus on the fully-online feedback mode, and Maximum Weight Vertex Search (MWVS) is an efficient algorithm to generate IDNC packets with the best-known completion delay performance. In this paper, we investigate IDNC for semi-online feedback transmission, in which the sender generates and broadcasts INDC packets round by round and collects feedback only after every round. Even though MWVS can be exploited to construct an IDNC scheme for semi-online feedback transmission, we demonstrate by an explicit example that such one may not have the optimal completion delay. We then modify MWVS so as to improve the completion delay performance of the constructed IDNC scheme. Moreover, we reveal that compared with the uncoded scheme, IDNC schemes constructed by existing fully-online feedback algorithms may not reduce the expected number of transmission rounds. We then design an efficient algorithm to construct IDNC schemes with fewer transmission rounds. Numerical analyses demonstrate an approximately 10% performance gain of the IDNC scheme constructed by our proposed algorithms over the one constructed by MWVS in terms of both completion delay and transmission rounds.