干扰对齐技术在认知无线电系统中的应用

发布时间：2018-06-08 17:11

本文选题：干扰对齐 + 机会干扰对齐　；参考：《西安电子科技大学》2014年博士论文

【摘要】：在无线通信系统中,干扰对齐技术作为抑制干扰的有效手段具有革命性的意义。干扰对齐的主要思想是通过多个发射机的协作使他们在不期望接收端产生的干扰相互对齐。干扰对齐技术也被扩展到认知无线电系统中,本文的研究工作围绕干扰对齐在认知系统中的应用展开。本文的主要工作与创新点总结如下:1.针对在有限的发射功率及干扰条件下计算多输入多输出(Multiple-input Multiple-output,MIMO)信道复用增益存在数值较小的问题,提出了用于衡量无线通信系统中MIMO信道相对传输能力的本质自由度(Intrinsic Degrees of Freedom,IDoF)参数,并以此为依据,给出基于认知无线电场景下的主用户空间维度分配方案及基于K用户MIMO干扰信道模型的用户空间维度分配方法。在多天线认知无线电系统中,次用户根据主用户子信道的不同传输效率(IDoF参数)分析其允许接入的空间机会(主用户的子信道传输能力为0),获得空间维度,实现与主用户频谱共享。在多用户干扰系统中,用户根据来自其他用户的干扰强度,确定其可能提供给干扰用户以实现干扰迫零的空间维数。2.针对不同小区内具有相同载波频率的多个用户可能存在空余空间资源的问题,提出基于符号扩展的移动次用户机会空间对齐方法,并将该问题建模为一个多约束的优化问题。K个主用户分布在K个小区并工作在相同频段,一个移动次用户通过空间对齐(Space Alignment,SA)方式期望占用主用户频谱资源。次用户在K个时隙内发送一个超级符号,在k时刻对主用户的干扰对齐在第k个主用户未使用的空间方向上,同时满足对其他K-1个主用户干扰温度的限制。性能仿真结果显示,我们提出的SA方法明显优于单主用户情况,在干扰温度较小情况下,在低SNR区域也优于D-SVD方法。3.针对现有的机会空间对齐方法对主用户的可靠性指标无约束的问题,提出了基于主用户传输中断概率约束的次用户空间对齐方法,并给出在小区内上行系统及小区间上行系统的具体实现及小区内上行系统次用户获得不同机会维数的概率。在认知系统中,主用户只利用满足门限性能要求的子信道传输数据,剩余子信道对应的空间维可以为次用户提供传输机会。多个次用户竞争有限空间维,按优先权先后顺序,同时采用和主用户一样的机制,只利用满足门限性能要求的子信道传输数据,余下的空余维依优先权次序分给下个次用户,直到空余的空间维为零。仿真结果显示,我们提出的计划,相比较现有的空间对齐方法,在性能上有明显优势。4.基于现有的MIMO干扰信道线性干扰对齐的可行性条件,提出达到MIMO干扰信道容量的干扰对齐维数分配方案,并据此给出PA-OIA算法,性能仿真结果显示,该算法相对现有的干扰对齐DIA算法,系统和速率明显提高但总自由度反而更小。
[Abstract]:In wireless communication systems, interference alignment as an effective means of interference suppression has revolutionary significance. The main idea of interference alignment is to align the interference generated by multiple transmitters at unwanted receivers. Interference alignment is also extended to cognitive radio systems. The research work in this paper focuses on the application of interference alignment in cognitive systems. The main work and innovation of this paper are summarized as follows: 1. In view of the problem of calculating the multiplexing gain of multiple-input multiple-output (MIMO) channel with limited transmit power and interference, the numerical value of the multiplexing gain is small. The intrinsic degrees of freedom (Intrinsic degrees of freedom) parameters are proposed to measure the relative transmission capacity of MIMO channels in wireless communication systems. The main user space dimension assignment scheme based on cognitive radio scene and the user space dimension assignment method based on K-user MIMO interference channel model are presented. In a multi-antenna cognitive radio system, the secondary users analyze the spatial access opportunities according to the different transmission efficiency and IDoF parameters of the primary user subchannel (the primary user's subchannel transmission capacity is 0), and the spatial dimension is obtained. The spectrum is shared with the primary user. In a multiuser interference system, the user determines the spatial dimension. 2. 2, which may be provided to the interference user according to the interference intensity from other users. Aiming at the problem that more than one user with the same carrier frequency in different cell may have free space resources, a new method of mobile sub-user opportunity space alignment based on symbol expansion is proposed. The problem is modeled as a multi-constrained optimization problem. K primary users are distributed in K cells and work in the same frequency band. A mobile secondary user is expected to occupy the main user spectrum resources through space alignment. The secondary user transmits a supersymbol in K time slots, and the interference to the primary user at k time is aligned in the direction of the space not used by the k primary user, and the interference temperature of the other K-1 primary users is satisfied at the same time. The simulation results show that the proposed SA method is superior to the single-user method, and the SA method is superior to the D-SVD method in the low SNR region when the interference temperature is small. Aiming at the problem that the existing opportunity space alignment method has no constraint on the reliability index of the primary user, a secondary user space alignment method based on the outage probability constraint of the primary user transmission is proposed. The realization of the uplink system and the intercellular uplink system in the cell and the probability that the sub-users of the uplink system in the cell get different opportunity dimensions are also given. In cognitive systems, the primary user only transmits data using subchannels that meet the threshold performance requirements, and the spatial dimensions corresponding to the remaining subchannels can provide the secondary users with transmission opportunities. Multiple secondary users compete for finite space dimension, in order of priority, and adopt the same mechanism as primary users to transmit data using only subchannels that meet the threshold performance requirements. The remaining spare dimensions are assigned to the next secondary users according to priority order. Until the spare space dimension is zero. The simulation results show that compared with the existing space alignment methods, the proposed plan has obvious performance advantages. 4. 4. Based on the existing feasible conditions for linear interference alignment of MIMO interference channels, a scheme for allocating the equal dimension of interference pairs to the capacity of MIMO interference channels is proposed. Based on this, a PA-OIA algorithm is presented. The performance simulation results show that, Compared with the existing interference alignment DIA algorithm, the system and speed of the algorithm are improved obviously, but the total degree of freedom is smaller.
【学位授予单位】：西安电子科技大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TN925;TN972

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