Applications Of Artificial Bee Colony Algorithm In WLAN Channel Allocation And TDRSS Task Scheduling Problems

In wireless communications, there are many resource optimization problems, which require the decision makers to give reasonable solutions without much computation time, such as the channel allocation problem in the Wireless Local Area Networks (WLAN) and the task scheduling problem in the Tracking and Data Relay Satellite System (TDRSS) discussed in the thesis. According to the characteristics of the above two problems, mathematical models are established respectively in the thesis, namely, the channel allocation model and the task scheduling model. Furthermore, methods based on the Artificial Bee Colony (ABC) Algorithm are proposed to solve the above two problems. Simulations validate the correctness and effectiveness of the proposed algorithms. Specifically, the mains content and innovations of the thesis lie in:(1)For a complex WLAN with multiple Access Points (APs), an analytical model that is based on network throughput computation is established to maximize the system utility. Furthermore, a quick channel allocation method is proposed to tackle the high computation complexity. Considering the fact that a WLAN adopts the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol to compete channels, the thesis adopts the Ideal CSMA Network (ICN) model to compute the network throughput, based on which an optimization model of WLAN channel allocation is established to achieve the maximum system utility. Furthermore, a channel allocation method based on the ABC algorithm is proposed in the thesis. Simulations show that the proposed algorithm can largely reduce the computation complexity with a cost of less than 2% utility loss.(2)For the task scheduling problem of TDRSS, an optimization model is established, based on which a task scheduling method based on the ABC algorithm is proposed. First, various constraints of the task scheduling are analyzed, such as multiple visible time windows constraints between the relay satellite and the user spacecraft, the task constraints submitted by the users, limited resources of the relay satellite, and so on. Taking all the above constraints into account, an optimization model with the target of maximizing the number of successfully scheduled tasks and guaranteeing that the task with high priority can be scheduled preferentially is proposed. Second, a task scheduling method based on the ABC algorithm is proposed in the thesis. Simulations show that the proposed algorithm outperforms other existing scheduling methods in terms of the number of successfully scheduled tasks, the algorithm running time and the fitness function evaluation.