Rate–Reliability–Delay Tradeoff of Multipath Transmission Using Network Coding

The concept of introducing network-coded packets as redundancy was proposed to improve the reliability of end-to-end packet transmissions in wireline/wireless networks, and the corresponding rate-reliability tradeoff has been studied in the literature. However, little attention has been focused on how to design a network code to reduce end-to-end packet transmission delay and even further on analyzing the corresponding rate-delay tradeoff. In this paper, we propose a packet-combining scheme based on network coding to reduce packet transmission delay between a source and destination pair connected by multiple disjoint paths. Improving the reliability of packet transmission is also addressed. Moreover, both rate-delay tradeoff and rate-reliability tradeoff of the proposed scheme are studied. New tradeoff points with fine granularity are achieved compared with the traditional repetition-based approach. Quality-of-service (QoS) provisioning is facilitated by our analysis because the network code can be adjusted to operate at the tradeoff point closest to the system QoS requirement. Finally, design of network codes that can provide multilayered reliability and delay guarantees for packets with different priority levels is investigated.