## 2 System Model  
### Opportunistic Transmission Model with Selfish Nodes  
In this paper, the opportunistic transmission-enhanced integrated UAV-ICV network consists of \(N\) ICVs and \(R\) UAVs. As shown in Figure 1, both ICVs and UAVs can be regarded as communication nodes, with functions such as information storage, carrying, and forwarding. In integrated UAV-ICV networks, the behavior of each communication node is typically social rather than isolated [6]. For example, a bus node may only forward message copies belonging to its bus company. Specifically, selfish behaviors can be categorized into two types: drop and non-forwarding. The \"drop\" behavior refers to a communication node receiving a message copy from another node but not forwarding it, instead dropping it. In contrast, the \"non-forwarding\" behavior refers to a communication node refusing to receive the message copy entirely. Additionally, this paper classifies the node types in integrated UAV-ICV networks into three categories. Specifically, selfish nodes are private cars without public service attributes, and they neither broadcast nor forward information when encountering traffic congestion. Normal nodes are ICVs (e.g., taxis and passenger cars), which have partial public service attributes and generate or forward traffic information based on demand. Voluntary nodes are government vehicles or UAVs with public service attributes, and they generate or forward traffic information whenever they move. To analyze the impact of selfish behavior on integrated UAV-ICV networks, this paper defines the degree of node cooperation. The cooperation level is evaluated based on a metric that is negatively linearly correlated with the selfishness of nodes. When the cooperation level of a node is 0, it is considered completely non-cooperative. When the cooperation level is 100, it represents the ideal state of full cooperation, where each node forwards information as expected. Based on this analysis, this paper defines the three types of nodes and provides specific calculation methods. Node cooperation type I (defined as \(i_{1}\)): This type represents the ideal state. In this case, all nodes in integrated UAV-ICV networks do not exhibit selfish behavior and only drop message copies due to energy exhaustion or a full cache. The cooperation level of type I is defined as \(C_{\text{I}}\). The total number of dropped message copies is denoted as \(E_{\text{drop}}\), and the total number of message copies that need to be forwarded is denoted as \(E_{\text{forward}}\). For type I, the node cooperation level can be calculated as  
\[C_{\text{I}}=1-\frac{E_{\text{drop}}}{E_{\text{forward}}}. \tag{1}\]  
Therefore, when the relay type is type I, information is directly forwarded. The number of hops experienced by the message copy is increased by one. Node cooperation type II (defined as \(i_{2}\)): In practical integrated UAV-ICV networks, there are inevitably some selfish nodes. It is assumed that different types of communication nodes are allowed to exchange messages with each other. However, selfish communication  
Figure 1: A diagram of opportunistic transmission-enhanced integrated UAV-ICV networks. nodes drop all message copies from other nodes that need to be forwarded. In contrast, non-selfish communication nodes do not drop the message copies from other nodes that need to be forwarded. Let the number of non-selfish communication nodes be \(N_{\text{non-sel}}\) and the number of selfish communication nodes be \(N_{\text{sel}}\). In this case, for type II, the node cooperation level \(C_{\text{II}}\) is given by  
\[C_{\text{II}}=1-\frac{N_{\text{sel}}}{N_{\text{non-sel}}+N_{\text{sel}}}. \tag{2}\]  
Therefore, when the relay type is type II, if the communication node carrying the source node's message copy is also of type II, the message is forwarded. In this situation, the number of hops experienced by the message copy is increased by one. Otherwise, the message copy is not == forwarded, and the number of hops experienced by the message copy remains unchanged.