On the Reliability of Multi-Hop Dynamic Spectrum Access Networks Supporting QoS Driven Applications

This paper addresses the problem of evaluating the reliability of a single-radio, multi-channel, multi-hop dynamic spectrum access (DSA) network supporting QoS-driven network services. We define reliability as the reciprocal of the probable number of transmission attempts required to ship each unit of application data successfully under a given demand. The demand represents the flow rate (per unit of time) at which an application needs to be served. We provide analytical methods of reliability evaluation for two classes of DSA network service. 1. A network servicing a single source-destination pair and 2. A network servicing a broadcasting or multicasting application where common data has to be disseminated to all or a subset of nodes in the network. All the nodes involved in data communication are secondary nodes, which access the channels reserved for primary users, in an unlicensed manner. Our methods take into account the channel capacities of the links and provide an useful and an important metric for the effectiveness of a dynamic spectrum access network for a given demand. These methods can also be used to find robust routing paths in such networks. The approach we use is based on concepts in mathematical theory of reliability and theory of network flows. Our methodologies are scalable, simple to implement and can be extended to all other types of communication networks and network applications. To the best of our knowledge, this is the first work to address reliability issues in DSA networks.