# A Comprehensive Evaluation Algorithm of Multi-Point Relay Based on Link-State Awareness for UANETs
## 1 Introduction  
In recent years, propelled by the rapid advancements in drone technology, Unmanned Aerial Vehicles (UAVs) have witnessed widespread adoption across various sectors, including aerial photography, 5G communication, agricultural and forestry monitoring, as well as search and rescue operations [1, 2]. In order to efficiently complete tasks, multiple drones need to establish Unmanned Aerial Vehicle Ad hoc Networks (UANETs) in the actual work process to support real-time and efficient collaborative communication between each other [3]. UANETs, a variant of the well-established Mobile Ad hoc Networks (MANETs), represent a prominent trend in wireless communication due to their diverse range of applications [4]. Compared to traditional mobile ad hoc networks, UANETs exhibit stronger mobility and are not restricted by terrestrial factors when moving in the air, leading to more frequent changes in network topology [5]. In UANET, the routing technology at the network layer is one of the core technologies. However, existing routing protocols are mostly designed for static networks and do not require real-time updates of link states [6], rendering them inadequate for the swift mobility characteristic of UANETs. Therefore, it is necessary to optimize and improve the existing routing protocols based on the current network operation status.  
OLSR is a proactive, table-driven multi-hop routing protocol [7]. In the network, information is mainly exchanged in the form of HELLO messages and Topology Control(TC) messages [8]. The process of link detection and neighbor discovery between nodes is accomplished through broadcasting HELLO messages. The MPR nodes forward TC messages to obtain link information in the network, ultimately establishing and maintaining the entire network topology, and applying relevant path algorithms to generate routes [9]. The MPR mechanism is the core technology of the OLSR protocol, effectively reducing message flooding [10]. This protocol is suitable for network applications requiring short-term concurrent transmission and low latency, and it is applicable to large-scale networks with high node density.  
In static sensor networks, research on topology control is relatively extensive. However, in dynamic networks, the transient nature introduced by node mobility leads to frequent changes in network topology, resulting in significant impact on network topology and posing great challenges to topology control [11]. Meanwhile, due to the rapid node mobility and frequent network topology changes in UANETs, direct use of the OLSR protocol often leads to increased likelihood of link failures, high network topology changes, and delays [12]. Moreover, only nodes selected as MPR, known as a message sorting station in the network, can forward control messages such as TC messages, while other ordinary nodes cannot [13]. At the same time, MPR nodes can generate link state information between themselves and MPR selection nodes. Therefore, research on MPR is highly necessary as it directly affects network performance.  
The structure of the remaining sections in this paper is as follows: Section 2 provides a review and analysis of the current related work. Section 3 introduces the relevant evaluation parameters and the process of the MPR selection algorithm in detail. In Section 4, the simulation process is elaborated, followed by a discussion and analysis of the simulation results. Finally, Section 5 summarizes the paper and identifies future research trends.