Abstract
The intensive deployment of cells in a wireless communication system may significantly increase the network capacity, but it may cause more complex and severe inter-cell interference. In order to effectively coordinate the interference, terminals in different cells are matched with the purpose of avoiding severe interference, called terminal matching, and a fast method is proposed in this article for multi-cell scenarios. By constructing a fully weighted graph of all the base stations with interferences as the weights, the minimum spanning tree method in graph theory is used to identify the coordination relationship among all the cells, and multiple coordination pairs can be obtained. For each coordination pair, terminal matching is modeled as a two-dimensional assignment problem between the coefficients after wavelet decomposition and Hungarian algorithm is applied to obtain their optimal match. Wavelet transform is used to extract the scale transformation coefficients describing the terminal features in each single cell, so that the optimization process can be accelerated because the amount of these coefficients is dramatically reduced after several layers of wavelet decomposition. The minimum Hamilton path method in graph theory is used to rank the terminals in each cell based on their key features, so that the coefficients lose as minimum useful information as possible during wavelet decomposition. Simulation results show that the performance of the proposed method reaches approximately the optimal matching obtained by traversing all the coordination possibilities among all the cells. Compared with the simulated annealing algorithm, the performance loss in terms of system spectral efficiency is only about 2%, but the proposed method requires only less than one thousandth of its computational time.
Highlights
With the emergence of a large number of intelligent terminal devices and all kinds of emerging applications, such as virtual reality, 3D media, and Internet of things, the network traffic explosively grows
From the above analysis and discussion, it can be seen that the proposed method can greatly improve the overall performance of the system by coordinating multiple coordination pairs with strong interference in the network
The main purpose of this paper is to effectively coordinate the interference between multiple cells in a short time, and a fast terminal matching method for interference coordination based on wavelet transform and graph theory is proposed
Summary
With the emergence of a large number of intelligent terminal devices and all kinds of emerging applications, such as virtual reality, 3D media, and Internet of things, the network traffic explosively grows. Kashaf et al [13] introduced a parameter for each cell to control the transmission power of the central frequency band, so as to reduce the interference of center users to edge users of the neighboring cells, and proposed a self-optimizing method of downlink inter-cell interference coordination parameters based on genetic algorithm. In [29], a method of dynamically adjusting the transmission power of small BSs to adapt to the dynamic changes of network was proposed It was modeled as a Markov decision process, and solved by the actor-critic algorithm. The multi-cell coordination problem degenerates into multiple two-cell coordination problems, which corresponds to multiple two-dimensional assignment problems Each of such problems can be directly solved by the Hungarian algorithm in polynomial time, so a fast terminal matching method integrating wavelet transform and graph theory is proposed in this paper.
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