数学建模美赛论文.docVIP

Repeater Coordination: Achieving communications with the fewest repeaters Summery Limited by the transmission characteristics of VHF radio spectrum, users far away from each other cannot communicate with one another. In general, it is through repeaters that the communication distance can be increased. However, with the increase of repeaters, mutual interference appears in the overlapping area of repeaters using the same frequency. Solution to this problem is to use different frequencies or adopt CTCSS technology. But due to the bandwidth limitations and the restriction on the number of PLs, the resources allocated to repeaters are limited, which is a challenge to the repeater’s configuration and to resource allocation. Therefore, with the aim to solve this problem, we established mathematical models with the aim the finish the following three tasks. For the given region, we established the optimal coverage model to guarantee that all users have enough communication channels and to minimize the number of cells that are needed to cover the given region completely. In the case of cell radius determination, we proposed two schemes respectively, based on the distance of user-to-user communication and between user-to-repeater communication, and obtained two kinds of results: 225 repeaters and 37 repeaters. The former uses more repeaters, but there are more channels in one cell. This scheme is suitable for the case that users are dense in a sub-cell. While the latter uses a smaller number of repeaters, but because the number of repeaters is smaller, PLs cannot be fully utilized, leading to fewer communication channels in each sub-cell. This communication system cannot serve a large number of users. To ensure that overlapping repeaters do not interfere with each other, we established the frequency and PL allocation model. By frequency and PL reuse, we increase the number of available remote communication channels as many as possible. When solving the PL reuse problem, we