###### Abstract  
Vehicular Ad Hoc Networks (VANETs) are increasingly playing a fundamental role in improving driving safety. However, VANETs in a sparse environment may add risk to driving safety. The probability of a low density of vehicles in a rural area at midnight is very high. Consequently, the packet will be lost due to the lack of other vehicles, and the arrival of the following vehicles in the accident area is unavoidable. To overcome this problem, VANET is integrated with Wireless Sensor Network (WSN). The most challenging features of VANETs are their high mobility. This high mobility causes sensor nodes to consume most of their energy during communication with other nodes, leading to frequent network disconnectivity. With the evolution of VANET and WSN, the Store/Carry-Forward (SCF) paradigm has emerged as an exciting research area in the Delay Tolerant Networks (DTNs) to solve network disconnectivity. This paper proposes the Energy-Mobility-Connectivity aware routing protocol (EMCR) for a hybrid network of VANET-WSN. A comprehensive performance analysis that considers realistic propagation models and real city scenario traffic is performed in NS3. The simulation results show that the SCF mechanism is essential in the EMCR protocol to maximize the delivery ratio and minimize energy consumption and overhead.  
delay tolerant network; vehicular ad hoc network; wireless sensor network; store-carry-forward; VANET; WSN; DTN; SCF +
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should immediately be forwarded to the following vehicles. In this situation, the probability of a low density of vehicles is very high. Thus, the packet will be lost due to the lack of other vehicles, and the arrival of the following vehicles in the accident area is unavoidable. Therefore, VANET is integrated with a WSN, an essential technology for the future Internet of Things (IoT). WSNs usually operate with batteries that cannot be rechargeable.  
In the hybrid network of VANET-WSN, the prime concern of routing is to discover and maintain up-to-date information about neighboring nodes, which can be acquired through the transmission of beacon messages. However, high mobility causes sensor nodes to consume most of their energy during communication with other nodes. This battery drainage leads to frequent network disconnectivity. Therefore, the high mobility and battery drainage result in a network partitioning, making it difficult for the packets to be delivered from the source to the destination [4]. In such dynamic environments, a delay tolerant network (DTN) [5; 6] uses the Store/Carry-Forward (SCF) mechanism for routing packets from source to destination. The SCF networking allows wireless communication nodes to act as intelligent relay nodes that can store or carry messages waiting for a better opportunity for transmission and then forward the packets to other nodes. The SCF mechanism is vital to solve the network disconnection problem and improve the efficiency of VANET and WSN.  
The main contribution of this paper can be summarized as follows:  
* We propose an effective data forwarding mechanism called the Energy-Mobility-Connectivity aware routing protocol (EMCR). The EMCR protocol considers the significant factors in the hybrid network of VANET-WSN to balance the energy consumption of WSN and the highly dynamic mobility of VANET and address network partitioning by adopting the SCF mechanism. SCF is essential for limited radio communication environments to solve network disconnectivity and maximize delivery at the destination. The EMCR protocol makes the hybrid network of VANET-WSN useful in a wide range of applications, from critical safety services to infotainment applications.