# A QoE-Oriented Uplink Allocation for Multi-UAV Video Streaming
## 2 Related Works
### The Allocation Method  
Although the traditional optimization method can better solve the problem of wireless resource allocation, not all problems can easily get the optimal solution. Especially when the optimization object contains multiple elements, the complexity of optimization methods will be further increased. This will bring a huge computing burden and big time delay to the real-time transmission service. In addition, the payloads of small UAVs cannot afford the high complex calculations. As we need to take the cluster of UAVs' video transmission into consideration, in order to avoid the complexity above, game theory method is chosen as the resource allocation algorithm in this paper. Game Theory is a branch of applied mathematics and the players can interact among themselves to obtain a stable allocation of system resources [25]. In general, it can be broadly divided into cooperative and non-cooperative games. We can find that game theory is already widely used in resource allocation and has played an effective role. In a cooperative game, the participants reach an agreement to obtain better overall benefits. Cooperative game can be divided into two-person cooperation and multi-person cooperation. The former is often called Nash bargaining problem and the latter is also called coalition game. Ref. [26] modeled the bandwidth allocation problem as a cooperative negotiation and considered both the fairness and the QoE. Ref. [27] regarded the UAVs as flying base stations and took the model of a  
Figure 1: A typical topology for communication of multi-UAVs. coalition formation game to deal with the trade-off between coverage and transmission performance. Although in the coalition game the multi-players' benefits are considered comprehensively, in practice, the formation of the coalition is often accompanied by losses, and it is difficult to always form a big coalition. In the optimization process of a coalition formation game, the participants will be selected, which means that some players will be excluded. Thus, a cooperative game method is not applicable to the scenario where each UAV has irreplaceable tasks. Compared with cooperative games, non-cooperative games pay more attention to the maximization of each player's own benefit, and their application is more popular. Ref. [28] modeled the offloading task as a replicator dynamic process. Ref. [29] proposed a Stackelberg dynamic game model to get the optimal allocated resources. Ref. [30] uses a non-cooperative game to achieve power allocation scheme. Although the development of non-cooperative game is relatively mature, in reality, the rules of non-cooperation are not absolute. More than that, with the further complexity of communication and network, the single non-cooperative game mode cannot solve the problem of resource allocation well. Ref. [31] established a two-level game framework, with an evolutionary game for underlying service and a differential game for upper bandwidth selection. Ref. [32] solved a spectrum pricing and allocation problem. The hierarchical two-level game framework included a Stackelberg game and a Bargaining game. Ref. [22] proposed a hierarchical game framework to solve the problem of joint access selection and bandwidth allocation. These multi-tier games are often used in scenarios where multiple problems need to be solved comprehensively, for example, when power control and channel selection are considered simultaneously, or when network service providers, secondary suppliers, and users make resource selection at the same time. Although the studies above have made some achievements, they are improper for the multi-UAV video transmission service. Especially in the application scenario of this paper, UAVs not only need to compete for resources, but also need to consider the overall consequences of video uplink brought by such competition. The nature quality of Potential Game (PG): the motivation of all players to change their strategies can be expressed as a global function [33], which could exactly meet this need.