Minimizing Video Retransmission Delay and Energy Consumption with Caching Routers

We investigated the use of caching of packets containing video at intermediary routers to reduce the delay and energy consumption of Automatic Repeat reQuest (ARQ) error recovery. We modeled the two mathematical programs that select the optimal set of routers to have caching ability, one to minimize energy consumption and the other to minimize retransmission delay. Both of these mathematical programs have identical structure. We then solve these mathematical programs with a dynamic programming solution whose execution time growth is polynomial in the size of the input parameters. Our performance analysis indicates that the optimal solution significantly outperforms several heuristic solutions.