## 1 Introduction
In Reference [28], a routing and dynamic spectrum allocation (ROSA) algorithm was proposed subject to spectrum allocation, scheduling and transmission power control scheme to maximize network throughput and limit physical interference to other users. Based on interference model, the authors of Reference [29] proposed joint routing, opportunistic spectrum scheduling and time sharing scheduling algorithms to minimize aggregate interference from cognitive users to a primary user. Besides, spectrum availability may change from time to time and hop by hop which is unpredictable. In Reference [30], the authors presented several types of prediction algorithms to forecast the node's locations. These prediction algorithms with Markov analysis, text compression, user's movement history and Bayesian and neural networks, significantly improved the system performance in mobile wireless systems. For improving routing reliability and scalability, the authors of Reference [31] used some prediction techniques to efficiently predict time of next movement and the next location of mobile nodes in MANETs. The authors of Reference [32] proposed an energy reduction multipath routing protocol by using a recoil technique (AOMDV-ER) in MANETs to improve the system performances. In AOMDV-ER, the mobile nodes used a varying recoil off time technique to establish the route to their destination based on the geographical location. In Reference [33], the authors proposed a topology change aware-based routing protocol choosing scheme (TARCS) for flying ad hoc networks to improve the system performances. In TARCS, mobile nodes can sense changes of the surrounding network topology periodically to provide a suitable routing protocol. In Reference [34], the authors proposed a node-disjoint multipath routing (NDMR) protocol to establish two node-disjoint paths between a source and a destination in a wireless network in order to solve the unstable state of wireless links, and unpredictable environmental interference. The proposed approach uses the request-reply mechanism to find the node-disjoint paths. In Reference [35], the authors presented a key exchange technique based on the fluctuating topology characteristic of MANETs. The ever changing topology of the network almost completely removes an active attacker's success ratio by using splitting key exchange information technique. However, the aforementioned works just focused on clustering or routing separately in conventional MANETs. Since the cost of established routes is greatly expensive, clustering is considered as an effective approach in simplifying routing process and reducing such a cost, that is, the size of routing space is reduced and energy balancing is achieved. In multi-channel cognitive radio environments, cognitive users have to be aware of channel status to establish a route from a source to a destination. Particularly, cognitive users first detect dynamically vacant channels to make a decision of either switching channel or using different regions to avoid the licensed spectrum in the transmission range of primary users [26; 28]. To provide comprehensibly the advantages of the proposed CRD protocol compared to the state-of-the art protocol, we summarize the main features in Table 1, where notation \"-\" is denoted as \"not mentioned.\"  
This paper proposes an efficient connected dominating set clustering based routing protocol with dynamic channel selection (CRD) in multi-channel cognitive mobile ad hoc networks (MCR-MANETs) to obtain high packet delivery ratio (PDR), low control overheads, low delay and low energy consumption when mobile nodes are moving in high speed. Moreover, CRD protocol can apply for Vehicular Ad Hoc Network (VANET), IoT and 5G. The main contributions of the paper can be summarized as follows:  
* We propose a CDS selection and a CDS size reduction algorithms to achieve a set of intermediate nodes which is latter used as a route searching space underlying infrastructure for routing process.