Efficient Cache Management for Network-Coding-Assisted Data Broadcast

Abstract

Network coding has been proven to be an effective technique in improving the performance of data broadcast systems. Previous studies have shown that the performance of network-coding-assisted data broadcast systems is highly related to client cache contents. In this paper, we investigate the cache management problem in network-coding-assisted data broadcast environments with the objective of minimizing the overall response time. We formulate the problem and prove that it is NP-hard. Furthermore, we derive a probabilistic model to analyze the decoding probability to give insight into the importance of the cache management scheme. On this basis, we propose a decoding-oriented cache management scheme, which is called decoding-oriented least recently used (DLRU), which incorporates decoding information in making cache replacement decisions. In addition, since individual clients may observe the global data access pattern from encoded packets broadcast by the server, we loosen the cache admission control policy and allow clients to cache decodable and potentially useful data items that are not currently being requested. Based on this idea, we further propose a variant scheme, which is called DLRU with cache partitioning (DLRU-CP), which couples the cache partitioning policy to DLRU. We build a simulation model and implement the most competing alternative solutions in the literature for performance evaluation. The simulation results conclusively demonstrate the superiority of the proposed schemes in terms of reducing the request response time in network-coding-assisted data broadcast systems.