Analyzing Opportunistic Request Routing in Wireless Cache Networks

To address the explosive increase in mobile data traffic in recent years, content caching at storage-enabled network nodes has been proposed. Alongside, a variety of forwarding strategies have been developed for wireless networks that exploit the broadcast nature of the wireless medium and the presence of time-varying fading channels to improve user performance. A widely popular forwarding strategy is opportunistic routing that opportunistically selects nodes that overhear packet transmissions to serve as ad hoc relays to forward the packet. In this paper, we investigate the request routing delay of a greedy opportunistic routing strategy for cache-enabled wireless networks considering uncorrelated and temporally correlated Rayleigh fading wireless channels. To this end, we develop Markovian models, leverage the wireless channel characteristics to determine the transition probabilities and then utilize them to obtain the request routing delay. Via numerical evaluation and simulation, we demonstrate the validity and effectiveness of our model in determining the request routing delay. We also investigate the impact of network parameters on performance through our experiments. Our work takes a step forward in providing network operators a tool for analyzing network performance before deploying their networks.