Abstract: Existing coding aware routing algorithms ignore a realistic question that different data packets reach the encoding node at different time. To overcome the above problem， an improvement scheme was proposed using a threshold value on the basis of existing coding-aware routing. Firstly encoding condition was used to find the nodes to encode. Then the network delay training phase was introduced to obtain the threshold value of waiting time. Lastly， it was decided whether to wait or not according to the relationship between the actual value and the threshold value. Simulation results show that the algorithm can achieve a better result than the traditional opportunistic coding policy in delivery delay and throughput.

Key words: network coding, delay, threshold value, tradeoff, routing