MIMO系统中基于SLNR的用户调度准则

多用户MIMO系统中,基于SLNR（signal-to-leakage-and-noise,信漏噪比）的预编码方案能够同时考虑噪声和信号泄漏问题,不但提高了系统性能,同时降低了系统的复杂度,但要求基站同时服务的数据流数之和不得大于其发射天线数. 因此,当用户数较多时,需要进行用户调度. 基于SLNR的用户调度准则只需要知道其他用户的信道信息,并能够合理的选择用户,通过仿真得知,该调度准则能够使系统获得良好的性能.     

基于SLNR准则的多点协作联合处理算法

多小区单用户联合传输能显著改善小区边缘用户的链路性能, 但降低了协作小区的平均吞吐量; 多小区多用户联合传输在改善小区边缘用户性能的同时, 通过协作小区内多个移动终端的复用, 提升协作小区的平均吞吐量。根据SLNR准则提出了一种单用户和多用户自适应切换的多小区联合处理算法, 结合协作集合选择、选择协作集合内的配对用户、MU-MIMO处理等形成一个完整的CoMP处理过程。该算法的单用户和多用户MIMO算法处理相似, 可简化系统处理过程, 并通过自适应选择单/多用户模式提高算法鲁棒性, 有利于提高CoMP的系统增益。根据LTE-Advanced系统的参数进行了系统仿真, 结果证明, 该算法性能优于多小区单用户联合处理和单小区多用户处理的性能, 可提高协作小区吞吐量25%~40%。     

Sub-channel shared resource allocation for multi-user distributed MIMO-OFDM systems

Well-controlled resource allocation is crucial for promoting the performance of multiple input multiple output orthogonal frequency division multiplexing （MIMO-OFDM） systems. Recent studies have focused primarily on traditional centralized systems or distributed antenna systems （DASs）, and usually assumed that one sub-carrier or sub-channel is exclusively occupied by one user. To promote system performance, we propose a sub-channel shared resource allocation algorithm for multiuser distributed MIMO-OFDM systems. Each sub-channel can be shared by multiple users in the algorithm, which is different from previous algorithms. The algorithm assumes that each user communicates with only two best ports in the system. On each sub-carrier, it allocates a sub-channel in descending order, which means one sub-channel that can minimize signal to leakage plus noise ratio （SLNR） loss is deleted until the number of remaining sub-channels is equal to that of receiving antennas. If there are still sub-channels after all users are processed, these sub-channels will be allocated to users who can maximize the SLNR gain. Simulations show that compared to other algorithms, our proposed algorithm has better capacity performance and enables the system to provide service to more users under the same capacity constraints.     

一种改进的SLNR多用户MIMO预编码方法

MU-MIMO系统中,基站在相同的时间与频率资源上与多个用户进行通信,导致不同用户之间存在同信道干扰。SLNR预编码方法将联合优化的问题转化成若干个独立优化问题,在系统性能与复杂度之间取到很好的折中。提出了一种改进的SLNR预编码方法,该方法在泄漏信号的基础上,考虑干扰信号的影响,对预编码向量进行迭代优化。仿真结果表明,与SLNR方法相比,该方法在理想CSI和非理想CSI情况下都可以进一步提高系统的吞吐量。     

一种基于信漏噪比的多用户优化预编码迭代算法

提出了一种新的基于信漏噪比的多用户优化预编码迭代算法。在深入分析和发掘系统设计中预编码矩阵和接收合并矩阵之间的内在联系的基础上,利用新提出的迭代算法解决其本质上存在的嵌套关系,从而实现系统综合性能优化。数字仿真从平均误码率与系统和速率两个层面对新算法进行验证。结果表明,新方案相较于原始基于信漏噪比的方案以及过去提出的其他经典方案具有明显性能优势。因其迭代算法收敛迅速,因此具有工程实践价值。     

Spectral efficiency evaluation of full‐duplex mode of communications based on SLNR approach

Full‐duplex (FD) mode of communication with efficient transmission scheme is a promising approach for 5G wireless systems by improving the spectral efficiency. This can be attained by making use of various precoding approaches. We propose a new co‐channel interference (CCI)‐aware improvement to signal‐to‐leakage‐and‐noise ratio (SLNR) technique and a suppression filter at the receiver to whiten the interference for the downlink channel. As well, for the uplink (UL) communication, we propose a self‐interference (SI)‐aware enhancement to SLNR scheme and designing a precoder using self‐interference plus noise covariance matrix. The total spectral efficiency is obtained from the sum‐rates of both downlink and uplink communication systems. Simulation results verify that the spectral efficiency (SE) of FD using the proposed scheme performs well relative to the half‐duplex system for all Rician factor and for small powers at the base station (BS) and UL communication channel users. Moreover, as the number of users grows, which entails that as the number of receiving antennas greater than the number of antennas at the BS the SLNR scheme still works, nonetheless, zero‐forcing (ZF) and block‐diagonalization (BD) precoding schemes failed. This is due to the fact that designing a precoder based on SLNR scheme supports multiple numbers of antennas at the base station and users compared with ZF and BD by compromising the interference and noise. However, for the cases of ZF and BD approaches failed due to both schemes require the number of transmit antennas at the BS to be larger than the sum of the receiving antennas at all users.     

一种基于SLNR预编码的天线与用户联合选择算法*

针对在多用户MIMO系统中天线与用户联合选择算法复杂度高的问题,依据SLNR预编码算法特点,提出了一种基于SLNR预编码的天线与用户联合选择算法。分析了天线与用户选择顺序对基于SLNR预编码算法的多用户MIMO系统性能影响,给出了先天线后用户的次最优选择策略。所提算法首先为每个用户选取最优的单天线,再利用贪婪思想进行用户选择。仿真结果表明,所提算法与穷举算法相比和容量性能在020 dB的信噪比范围内损失均保持在1.6 dB左右;而误比特性能与穷举法相比在10-3有2 dB左右损失,但是所提算法复杂度与穷举法相比下降明显。     

Leakage-based user scheduling in MU-MIMO broadcast channel

This paper investigates user scheduling in multi-user MIMO broadcast channel. We propose a leakagebased user scheduling scheme, in which a user’s leakage power to other users is an important factor to determine whether the user should be selected. The accuracy of closed-form solution of SLNR (signal to leakage plus noise ratio) makes the proposed scheme outperform the traditional scheduling method based on SINR (signal to interference plus noise ratio). The proposed algorithms can work in case of perfect or limited feedback of CSI (channel state information) at transmitter, and the advantage is verified with numerical results. A tradeoff relation among feedback bits number, active user number and transmit/receive antennas number is analyzed, which serves as a system design guideline.     

基于信泄噪比的改进预编码算法研究

为改善用户自身天线间的干扰和信道噪声干扰对SLNR算法性能的影响,对SLNR算法进行了改进,包括两种改进算法：SLNR_ZF算法是利用ZF算法可以消除用户自身天线间干扰的作用将其引入到SLNR算法中;SLNR_MMSE算法是在SLNR_ZF算法的基础上引入规范化因子,消除噪声干扰。通过仿真结果表明,改进的两种优化算法可以有效地消除包括用户自身天线间干扰、用户间干扰和噪声干扰的多种干扰,提高小区边缘用户的吞吐量和误码率。     

多小区MIMO系统中基于泄漏的多用户下行链路预编码新算法

针对多小区MIMO系统的多用户下行链路预编码设计是未来移动通信系统研究的重要内容之一。本文在蜂窝多小区MIMO通信环境下,基于信漏噪声比(Signal-to-Leakage-Noise Ratio,SLNR)最大准则,提出了改进的多用户下行链路线性预编码算法。通过在优化目标中考虑接收端白化滤波器的影响,该预编码算法实现了对用户间干扰和小区间干扰(OCI)的同步抑制消除;在求解预编码矩阵优化问题时,本文基于QR分解提出了一种新的低复杂度求解算法,该算法能以较低的计算复杂度实现系统性能的有效提升。仿真实验结果表明,本文的改进SLNR线性预编码算法能有效抑制小区间干扰(OCI)的影响,使多小区MIMO系统获得更高的和速率(Sum Rate)容量。