共查询到19条相似文献,搜索用时 78 毫秒
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大规模MIMO多小区TDD系统中的预编码策略和导频调度 总被引:1,自引:0,他引:1
上行导频污染是大规模MIMO多小区多用户TDD系统的主要性能瓶颈。本文推导了下行链路中MF,ZF单小区预编码,基于MMSE的多小区预编码以及基于最大化SLNR准则的预编码策略在有导频污染的大规模MIMO下的系统可达和速率渐近性能,发现当基站天线数趋向无穷时,各个策略的等效信干比均收敛到仅与大尺度衰落因子相关的一个比值,由此可以得到一个系统可达和速率的渐近结果。基于此渐近结果,以最大化系统可达和速率为目标,获得了一个导频调度方案,即使得小区间相互干扰较小的用户采用相同的导频而相互干扰较大的用户采用正交的导频,从而在存在导频污染的情况下,可以提升系统的整体性能。理论分析和数值仿真结果都验证了以上结论。 相似文献
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在数字通信系统中,调制技术和信道编码技术是最为关键的物理层技术,它们分别决定着系统的频谱利用率和可靠性.MIMO(Multiple Input and Multipul Output,多输入多输出)技术作为一项空域调制技术,可同时由多根天线发送数据,提高了频谱利用率,在接收端利用信号之间的空域自由度进行检测;LDPC码也被证明是目前在各种信道条件下最接近香农信道容量的信道编码技术.在新一代5G数字通信系统的技术研究中,目前已经确定LDPC编码和大规模MIMO分别入选长码数据编码和调制的技术方案.本文将对这两项关键技术的概念和性能进行简要介绍,以期帮助移动通信从业人员建立对这些技术及其性能优势的基本认识. 相似文献
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《无线电通信技术》2017,(5)
在大规模MIMO系统中,小区间使用合理相移后的导频序列而非复用同一组导频,能以导频长度的适当增加换取导频污染水平的下降。但已有研究在优化各小区导频相移量时未考虑小区间的实际干扰情况,而且在相移导频方案下传统基于贪婪搜索的协作式导频分配方法已不再适用。针对上述问题,选择与大尺度信道信息有关的系统总干扰最小作为优化目标,搜索得到更优的导频相位偏移值,降低导频污染水平;在所设计的相移导频方案基础上,采用低复杂度的禁忌搜索算法实现对各小区用户的协作式导频分配,进一步降低导频污染的影响。仿真实验表明,所设计的上行导频方案可以提高信道估计精度,进而提升下行用户传输速率。 相似文献
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多用户MIMO调度方法无法达到预期的调度效果,为此,文章提出面向5G网络的多用户MIMO调度方法。建立5G网络MIMO信道模型,根据用户调度优先级对用户分组,根据用户信道之间的相关性,确定调度候选组中的用户调度顺序,以此完成面向5G网络的多用户MIMO调度。实验结果表明,应用此方法5G网络MIMO信道平均吞吐量、速率均有明显的提升,具有良好的应用前景。 相似文献
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相比于传统多输入多输出(MIMO)系统,大规模MIMO的天线数量大幅增加,使得系统的容量提升、误比特率下降,但也造成预编码矩阵维度升高,算法复杂度、系统成本及实现难度增大。将大规模MIMO系统主要采用的预编码技术分为线性和非线性两个部分,对两者进行了归纳和对比,并着重介绍了几种经过简化的线性预编码算法和几种比较典型的非线性预编码算法,指出因为非线性算法的复杂度很高,故未来大规模MIMO系统的预编码应当以线性算法为主。 相似文献
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Pilot contamination is appeared in massive MIMO (multiple input multiple output) system when using the same pilot sequences at different cells to get the channel state information.It becomes a bottleneck problem of massive MIMO when the number of antenna goes infinite.In order to dealt with pilot contamination,a new TS-CSPA joint scheme was proposed.This scheme can mitigate pilot contamination by reduce the reuse of pilot sequence through the time domain and space domain.And the closed-form expression for the achieved rates and signal to interference plus noise ratio(SINR) to verify the advantages of the proposed scheme were given.Numerical results show that significant performance gains to mitigate pilot contamination problem compared to other methods. 相似文献
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The performance of massive multiple-input multiple-output (MIMO) system is limited by pilot contamination. To reduce the pilot contamination, uplink and downlink precoding algorithms are put forward based on interference alignment criterion. In the uplink receiving processing, the target function aligns the pilot contamination and the interference signals to the same null space and acquires the maximal space degree of the desired signals. The uplink receiving precoding matrix is solved on maximal signal to interference plus noise ratio (SINR) criterion considering the impact of the pilot contamination on channel estimations. The uplink receiving precoding matrix is used as the downlink transmitting precoding matrix. Exploiting the channel reciprocity, it is proved that, if the uplink receiving precoding matrix achieves maximal S1NR, the identical precoding matrix can be used in the downlink transmission and acquires maximal signal to leakage plus noise ratio (SLNR). Simulations show that the spectrum efficiency of the proposed algorithm can reach about 1.5 times higher than that of popular matched filtering (MF) precoding algorithm, and about 1.1 times higher than multi-cell minimum mean square error (MMSE) precoding algorithm. The performance of the proposed algorithm can be improved approximately linearly with the increasing of the number of antennas. 相似文献
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导频污染问题是限制大规模多输入多输出(MIMO)系统性能的主要影响因素.针对这个问题,提出了一种基于改进预编码和最优导频分配策略的大规模MIMO系统导频污染抑制算法.首先,在系统下通过基于改进遗传优化算法的最大化信干噪比(SINR)预编码算法,获得最优预编码矩阵;然后,通过基于用户信道条件优劣的最优导频分配策略对每个小区用户进行导频分配,从而实现大规模MIMO系统导频污染抑制.通过Matlab仿真结果可知,相对于传统的SINR预编码算法,所提算法的复杂度降低了65%左右,而导频污染抑制性能提升了30%左右.该算法能够有效抑制导频污染,提升大规模MIMO系统的性能. 相似文献
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研究第五代(the 5th Generation, 5G)移动通信场景下的无线信道新特征及其对5G关键使能技术的影响是当前亟待开展的工作.文章从5G应用的主要场景和其中部分关键使能技术出发, 基于国内外相关文献调研结果, 阐述了以高频段通信、大规模天线阵列和终端直接通信技术为背景的无线信道建模的主要需求、当前进展、存在的挑战并指出未来5G信道建模理论发展的五个主要趋势, 可能的研究成果将为相关算法在5G连续广域覆盖场景、热点高容量场景、低功耗大连接场景和低时延高可靠场景下的匹配设计和准确性能评估打下坚实的基础. 相似文献
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为了克服大规模MIMO的技术瓶颈——上行链路导频污染,与现有盲导频去污染中系统参数同时设计的方法不同,提出了系统参数的分层设计方法,指出不同的系统参数对最终接收信号样本协方差矩阵谱精确分离的作用是不同的,即具有不同的优先级。然后,发现要实现谱分离,期望信号的功率并不一定要高于干扰功率,两者之间的差异才是决定因素。更进一步地,在导频序列长度小于基站接收天线数这种更实际的场景下,首次给出了一种数值算法同样能实现上述的精确谱分离。实验仿真证明,由于分层的参数设计保证了渐近谱的精确分离,所提方案比现有的盲导频去污染方案更适合实际应用。 相似文献
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Nazanin Kalantarinejad Dariush Abbasi‐Moghadam 《International Journal of Communication Systems》2020,33(3)
Pilot contamination (PC) is one of the most crucial problems in massive multiple‐input multiple‐output (MIMO) systems, due to a limited source of the coherence block. In the current study, two pilot assignment schemes proposed for massive MIMO uplink transmission. We divided each cell into two groups of edge and center users under distance‐based user grouping algorithm (DUG), which the aim is finding the best user grouping boundary. The best boundary is where both signal to interference plus noise Ratio (SINR) of edge and center users is maximum, according to the user's distance to base stations (BS). We investigated the location‐aware pilot assignment (LPA) scheme to enhance the quality of services for both groups. In LPA by assuming three pilot groups for adjacent cells and determining the user's distance to BS, the planned pilots assigned to the users according to their distance to the BS. Then, we optimized pilot schedules in each group by maximizing uplink (UL) rate of each user with auction‐based optimization pilot assignment (AOPA). Simulation results show that both DUG and LPA improve the rate of edge users about 70% and the rate of center users about 30%. Joint DUG and AOPA enhance the rate of the edge and center users about 100% and 80% in each group than conventional schemes and about 50% and 10%, compared with the LPA method. Simulation results show that the proposed method is efficient in reducing PC and improving spectral efficiency. 相似文献