Implementation and experimental results of decentralized coded caching for wireless video transmission

Coded caching in a broadcast link proposed by Maddah-Ali and Niesen can significantly reduce peak-hour traffic by exploiting coded multicasting opportunities. In this paper, we develop a testbed to validate the performance of decentralized coded caching for video transmission in a real wireless environment. Our testbed is built upon USRP (hardware platform) and GNU Radio (software development tool) and contains one server and three clients. The system operates in two phases, a cache placement phase and a content delivery phase. In the cache placement phase, the server selects at random some packets of each video file to transmit and cache in each client subject to the cache size limit. In the content delivery phase, each client requests a distinct video file and the sever delivers the uncached packets of each requested file using coded multicasting. We propose and implement a novel packet structure so that multicast transmission is realized at the physical layer. Experimental results of the actual delivery time and traffic load at the content delivery phase are generated. It indicates that coded caching indeed outperforms uncoded caching. The performance of coded caching compared to uncoded caching becomes better as the normalized cache size increases.