# Energy Transmission and Equilibrium Scheme in Data Communication Opportunistic Networks
## 1 Introduction  
In recent years, with the rapid development of the wireless network, a new type of wireless network called the opportunistic network was integrated into people's lives and has attracted the attention of domestic and foreign researchers. The opportunistic network originated from delay tolerant networks (DTN), a network of nodes connected wirelessly. The communication range between two connected nodes is not further than walking distance. Nodes are connected only temporarily, and the network topology may change due to the node movement or node activation and node deactivation, respectively. Nodes in the opportunistic network cooperate to forward the routing messages of other nodes in a coordinated manner and realize the communication hop-by-hop through the opportunities of encounters caused by the node movement [1; 2; 3; 4]. The opportunistic network has been widely used in post-disaster communication, animal tracking, vehicle network, and other fields, with the rapid development of 5G wireless communication technology and IoT [5; 6; 7; 8]. The model in the smart city in IoT, such as the energy supply bus [9], unmanned aerial vehicle with an energy supply [10], and the opportunistic network, has shown a broad application prospect. With the explosive growth of data in wireless communication networks, the transmission load increases massively. However, nodes do not have enough capacity to transmit such a large amount of data. At the same time, the nodes also need to do a computation to perceive the information of the neighbor nodes and choose the most appropriate node for message transmission [11; 12; 13; 14; 15; 16; 17]. To get thelowest delay average and the highest delivery ratio in the information transfer process, the multi-copy policy is widely used. According to the difference of the copy processing method for the transmission process, policies can be divided into the copy-based policy and the forwarding-based policy. Direct delivery [18], epidemic [19], spray and wait [20] are typical copy-based policies. They spread messages by sending multiple copies to the network to achieve a higher success delivery ratio. Although flooding or controlled copy dissemination can improve the delivery probability of messages, there is still the blindness of message dissemination, especially in the network with limited network resources [21]. The consumption of the copy has a great impact on the network performance. Bubble rap [22] uses the strategy based on \"forwarding\", which does not copy messages in the information transmission process. This kind of strategy selects the most appropriate next-hop node by analyzing the location, node intimacy, movement history, and other environmental information [23; 24; 25], and predicting the encounter of nodes. Although it can reduce the energy consumption, it causes a large number of messages to flow to the nodes with high activity, resulting in a heavy load and network congestion. Although the multi-copy strategy effectively improves the delivery ratio and reduces the delay, it does bring more network overhead, especially when spreading the copies blindly by the flooding method [24; 25]. Therefore, to reduce the congestion of nodes and improve the delivery ratio, we must calculate the proper number of copies, and deliver messages as accurately as possible. To achieve the above goals, the algorithm design must take node intimacy, reliability, congestion, and energy consumption into consideration. This paper introduces the priority selection delivery routing algorithm (PSDRA), which ensures the accurate delivery of the message and effectively reduces the system overhead. The contributions of this paper mainly include:  
1. Estimating the extent of message dissemination based on the message dissemination and the characteristics of node movement. 2. Estimating the delivery ratio of message copy by combining the dissemination of message copy and node connection strength. 3.