Performance Analysis of Caterpillar RLNC for Multi-Hop Communication

Vehicle Platooning combines lower fuel consumption with safe and efficient transportation in a cooperative driving application. To ensure this, vehicles must communicate quickly and reliably. The sliding window protocol Caterpillar Random Linear Network Coding (CRLNC) is used as it does not rely on acknowledgements and uses network coding to reduce losses. However, the protocol was intentionally designed for single hop scenarios. Therefore, three contributions to the CRLNC protocol are presented in this paper to optimize it for multi hop/single path transmissions. The contributions are idle-slot-management, adaptive-window, and queue-management. By effectively combining these contributions, a large gain in throughput of up to 40% is achieved. Furthermore, it was investigated what are the optimal protocol parameters for CRLNC in single path scenarios are. It is shown that the best transmission in terms of throughput and delay is achieved, when the code rate is less than one minus the error probability and a large window size is used. Even if the error probability is unknown, a large window size will bring more benefits to the transmission.