# Mobility-Enhanced Reliable Geographical Forwarding in Cognitive Radio Sensor Networks
## 1 Introduction
It proposes a comprehensive routing strategy that considers PU activity (to take care of routes that have to be built through PU coverage), PU signal protection (by the introduction of a mobility-induced guard (mguard) distance) and the random mobility-induced spatio-temporal spectrum opportunities (for enhancement of throughput). It also addresses the issue of frequent route maintenance that arises when speed of the mobile nodes are considered as a routing metric. In this respect, MROR will be the first that considers the speed of mobile nodes in the creation of routing paths. In addition, it also addresses the \"weak links\" phenomena by considering the link quality of communicating nodes before data forwarding. This was addressed by disconnecting between the assignment of the channel and the next hop process via the formation of virtual clusters. This approach is contrary to the prevalent routing approach usually adopted for CR based _ad hoc_ networks [9]. In MROR, the control channel (CC) is utilized for control signaling, while searching for all possible routes (between source and sink nodes) is handled by the route request phase. Based on the developed mobility-based bandwidth estimation and delay, the sink is made to select the best route that supports the required quality of service (QoS) level. In the dynamic reactive forwarding process of MROR, initially, all nodes along the chosen path are referred to as local minimum resolution (LMR) nodes. Then, by introducing a virtual mobile handover (VMH) zoning system, these roles are seamlessly transferred to eligible mobile nodes as long as the path remains active. Based on the correlation of spectrum opportunities, the route reply process is used to group the neighbors of each LMR node into a virtual contention (VC) group. The data forwarding phase is handled by the VC group (VCG) receiver-based contention forwarding scheme. A VCG refers to the grouping of nodes around an LMR based on available spectral coloration. This scheme is used for reduction of media access contention among participating nodes, which in effect increases the chance of successful data transfer across the VCGs to the sink. Simulation resultsshow how the MROR framework effectively utilizes CR capabilities to improve communication in MCRSN and seamlessly manage the mobility factor to greatly reduce frequent route maintenance activities when compared to similar solutions. In the implementation of a reliable and efficient mobility-enhanced geographical forwarding scheme for MCRSNs, the major contributions this work achieves can be outlined as follows: (i) the mobility-induced route instability in MCRSNs is resolved by incorporating a channel availability model into the routing metrics that reflects the fluctuation of mobility-induced spectrum opportunities; (ii) the scheme provides a framework for boosting throughput in MCRSNs, by compensating the degradation in the sensitivity of energy detection by the spatial-temporal diversity of the mobile nodes; (iii) in order to ensure primary user (PU) signal protection, the scheme introduces the use of a mobility-induced guard (mguard) distance, which is jointly considered with the random mobility, induced spatio-temporal spectrum opportunities and the PU activity (to take care of routes that have to be built through PU coverage). In this regard, MROR will be the first to implement mobility-enhanced, lossy link-aware geographic forwarding for MCRSNs. This paper is organized as follows: The motivation for this work is discussed in Section 2. In Section 3, a review of relevant and related works on routing in CRSN is discussed. In Section 4, the mobile channel availability model is presented. Section 5 the features, the detailed functions and the operation of the modules that make up MROR are discussed. In Section 6, the results for the performance evaluation are discussed. Section 7 presents a comparative analysis of MROR with related works. Section 8 concludes the paper.