LTE系统基于SFR的小区用户划分算法研究

发布时间：2018-04-15 23:28

本文选题：OFDM + MIMO　；参考：《兰州交通大学》2017年硕士论文

【摘要】：随着4G技术的不断完善,LTE网络已在我国大规模商用。虽然LTE系统利用OFDM技术解决了小区内干扰问题,但其使用的同频组网方案又给系统带来了严重的小区间干扰。为了解决小区间干扰,3GPP制定了几种干扰抑制方案,主要包括干扰随机化、干扰消除和干扰协调三种,其中干扰协调因为成本低,可实现性好,成为了干扰抑制技术的主流。干扰协调技术同样也存在缺陷,尤其是用户划分算法会直接影响它的性能,因此,论文将提出一种新的用户划分算法,以期能完善干扰协调技术并减轻小区间干扰。论文首先介绍了LTE的网络结构和空中接口,随后分析了OFDM技术和MIMO技术,这两种技术既是4G的核心,又决定了LTE网络的抗干扰能力,其中OFDM技术能有效提高系统的频带利用率,并减轻多径效应,而MIMO技术可明显改善系统的吞吐量和可靠性。文中还介绍了几种干扰抑制方式,其中包括了干扰协调技术中的SFR方案和FFR方案。由于SFR方案性能优秀,且兼具灵活性和实用性,因此论文将以它为基础对改进算法进行研究。为了测试改进算法的性能,文中基于SFR技术搭建了LTE系统级仿真平台,平台搭建分两步完成,首先需要根据LTE协议规范确定仿真流程和基本参数;随后需要从基站、用户、噪声模型、业务模型、阴影衰落等方面进行建模仿真。论文还列举了系统的性能评估参数,主要包括SINR和吞吐量两种。仿真平台搭建完成后,论文又研究了用户数目变化时SFR技术的性能,此处得到的数据,可与后文的仿真结果作对比。本文研究的重点是SFR中用户分类算法对系统性能的影响,因此文中简要讲解了几种SFR中的用户划分算法,并详细分析了它们的缺点,原有的用户划分算法普遍使用固定阈值对用户进行一次性的分类,这种分类方式虽然简单,但准确性不高。针对原有算法的不足,论文提出了一种同时考虑距离和SINR的用户划分新方案,改进后的算法能准确找到小区中受干扰最严重的中距用户,并对他们进行更合理的二次划分。本文在提出新算法的同时,也进行了仿真验证,仿真结果表明,新的用户划分算法能更加有效地利用频带资源,同时提升边缘用户的吞吐量,论文据此得出了改进算法比原有算法更优秀的结论。
[Abstract]:With the continuous improvement of 4G technology, LTE network has been widely used in China.Although the LTE system uses OFDM technology to solve the problem of intra-cell interference, the scheme of co-frequency network has brought serious inter-cell interference to the system.In order to solve the problem of intercellular interference (3GPP), several interference suppression schemes have been developed, including randomization of interference, elimination of interference and coordination of interference, among which interference coordination has become the mainstream of interference suppression technology because of its low cost and good realizability.Interference coordination technology also has some defects, especially the user partition algorithm will directly affect its performance. Therefore, this paper will propose a new user partition algorithm in order to improve interference coordination technology and reduce inter-cell interference.This paper first introduces the network structure and air interface of LTE, then analyzes the OFDM technology and MIMO technology. These two technologies are not only the core of 4G, but also determine the anti-jamming ability of LTE network. OFDM technology can effectively improve the frequency band efficiency of the system.And reduce the multipath effect, and MIMO technology can obviously improve the throughput and reliability of the system.Several interference suppression methods are also introduced, including SFR scheme and FFR scheme in interference coordination technology.Due to the excellent performance, flexibility and practicability of the SFR scheme, this paper will study the improved algorithm based on it.In order to test the performance of the improved algorithm, this paper builds a LTE system-level simulation platform based on SFR technology. The platform is built in two steps. Firstly, the simulation flow and basic parameters need to be determined according to the LTE protocol specification.Noise model, traffic model, shadow fading and other aspects of modeling and simulation.The performance evaluation parameters of the system are listed, including SINR and throughput.After the completion of the simulation platform, the performance of SFR technology is studied when the number of users changes. The data obtained here can be compared with the simulation results.This paper focuses on the impact of user classification algorithms in SFR on system performance. Therefore, several user partition algorithms in SFR are briefly explained, and their shortcomings are analyzed in detail.The original user partition algorithm generally uses fixed threshold to classify users at one time. Although this classification method is simple, but the accuracy is not high.In view of the shortcomings of the original algorithm, a new user partition scheme considering both distance and SINR is proposed. The improved algorithm can accurately find the most seriously disturbed users in the cell, and give them a more reasonable quadratic partition.In this paper, the new algorithm is proposed, and the simulation results show that the new user partition algorithm can make more effective use of frequency band resources and improve the throughput of edge users.Based on this, the conclusion that the improved algorithm is better than the original algorithm is obtained.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.5

【参考文献】