Blind Instantly Decodable Network Codes for Wireless Broadcast of Real-Time Multimedia

Abstract

Instantly decodable network codes (IDNCs) are suggested in the literature to mitigate the problem of decoding delay in network coding. IDNC is also suggested for broadcast scenarios, where the goal is to maximize the number of decoded packets by the receivers, e.g., in multimedia broadcast. It is shown that after uncoded transmission of all the packets, one coded packet can be instantly decodable by a large number of users, when the transmitter is sighted, i.e., it has a perfect knowledge of the lost packets by each receiver. We introduce and study blind IDNC for broadcast, where the transmitter has no knowledge of the lost packets. Similar to the sighted IDNC, first all data packets are transmitted uncoded. Then, assuming the same erasure rate for all users, we allow a small number of coded packets (one, two or three), and study how these coded packets should be constructed to recover as many lost packets at the receivers as possible. The optimal solutions when one blind packet or two non-overlapping blind packets are transmitted are found. We see that two blind transmissions have comparable performance to a single optimal sighted transmission. Moreover, we prove that three blind transmissions outperform any single sighted transmission.