MIMO异构下行网络干扰对齐关键技术研究

发布时间：2018-12-14 23:54

【摘要】：随着通信技术的快速发展,人们对数据传输的速率和容量的要求越来越高,如何在有限的频带资源内来满足这种高要求是一个非常重要的课题。多输入多输出技术因为可以增加系统的传输速率而得到了快速的发展。为了支持高密度的用户进行通信,未来将采用宏基站和众多微基站混合的异构网络。而在异构网络中存在的小区间的干扰和用户间的干扰会大大影响系统的自由度。为了解决异构网络中严重的干扰问题,近年来提出了许多方案对干扰进行管理,其中干扰对齐是一种关键技术。对齐技术主要是通过将多个干扰信道进行管理,使得这些干扰信号占据一个维度更小的空间,来为期望信号提供更大的传输空间。首先,介绍了MIMO技术和异构网络,研究了干扰对齐技术的基本原理以及核心思想,同时利用自由度来衡量系统容量。其次,详细分析了一种适用于MIMO同构网络的干扰对齐方案。该方案利用零空间的思想实现干扰消除。但这种算法仅适用于同构网络,并没有提出异构网络下可行的干扰对齐算法。此外,研究了一种适用于MIMO异构网络的非迭代的干扰对齐方案。该方案利用合理分配干扰信道的方法进行干扰对齐和消除。然而,这种算法只适用于宏用户和微用户拥有固定数据流的场景。针对现有方案的不足之处,本文提出了一种适用于MIMO下行异构网络的基于二级零空间和干扰子空间分配的干扰对齐方案,同时给出了本方案可行的天线约束条件。本方案利用二级零空间技术消除微基站对宏用户的干扰以及微基站对其他微小区中用户的干扰。具体来说,第一级零空间用来消除宏基站对微用户的干扰,而第二级零空间用来消除微基站对其他微基站中微用户的干扰。同时,使用干扰子空间分配方法先将微基站对所有宏用户的干扰对齐到若干个干扰空间中,并对此小区间干扰以及微用户之间的干扰进行消除。然后使用迫零的算法来消除用户之间的干扰。本文提出的基于二级零空间和干扰子空间分配的干扰对齐技术可以有效地消除用户接收到的小区间干扰和用户间干扰。最后,针对本文提出的算法,在相同的系统配置下,通过系统仿真与现有干扰对齐方案的可达自由度进行对比分析。根据仿真结果,可以得出本文提出的基于二级零空间和干扰子空间分配的干扰对齐技术可以获得更大的可达自由度。
[Abstract]:With the rapid development of communication technology, the demand of data transmission rate and capacity is becoming higher and higher. How to meet this high demand in the limited frequency band is a very important issue. Multi-input multi-output technology has been developed rapidly because it can increase the transmission rate of the system. In order to support the communication of high density users, a heterogeneous network with a mixture of Acer stations and many microbase stations will be adopted in the future. However, intercellular interference and interuser interference in heterogeneous networks will greatly affect the degree of freedom of the system. In order to solve the serious interference problem in heterogeneous networks, many schemes have been proposed in recent years to manage interference, among which interference alignment is a key technology. Alignment technology mainly manages multiple interference channels to make these interference signals occupy a smaller space in order to provide a larger transmission space for desired signals. Firstly, the MIMO technology and heterogeneous network are introduced, and the basic principle and core idea of interference alignment technology are studied. At the same time, the system capacity is measured by degrees of freedom. Secondly, an interference alignment scheme suitable for MIMO isomorphism network is analyzed in detail. The scheme uses the idea of zero space to eliminate interference. However, this algorithm is only suitable for isomorphic networks and does not propose a feasible interference alignment algorithm for heterogeneous networks. In addition, a non-iterative interference alignment scheme for MIMO heterogeneous networks is studied. The scheme uses reasonable allocation of interference channels to align and eliminate interference. However, this algorithm is only suitable for scenarios where macro and micro users have fixed data streams. In view of the shortcomings of the existing schemes, this paper proposes an interference alignment scheme based on two-stage null space and interference subspace allocation for MIMO downlink heterogeneous networks. At the same time, the feasible antenna constraints of this scheme are given. In this scheme, the interference of microbase station to macro user and the interference of microbase station to other users in microcell are eliminated by using two-stage null space technology. Specifically, the first stage zero space is used to eliminate the interference of the macro base station to the micro user, and the second stage zero space is used to eliminate the interference of the micro base station to the micro user in the other micro base stations. At the same time, interference subspace allocation method is used to first align the interference of microbase station to all macro users into several interference spaces, and eliminate the interference between microusers and this inter-cell interference. A zero-forcing algorithm is then used to eliminate interference between users. The proposed interference alignment technique based on two-stage null space and interference subspace allocation can effectively eliminate inter-cell interference and inter-user interference received by users. Finally, for the proposed algorithm, under the same system configuration, the system simulation is compared with the available interference alignment scheme of the reachable degree of freedom. Based on the simulation results, it can be concluded that the proposed interference alignment technique based on two-level null space and interference subspace allocation can obtain greater degree of freedom.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN919.3

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