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基于多中继导频频分复用的协同通信系统信道估计算法 总被引:1,自引:0,他引:1
本文针对频率选择性衰落环境下结合正交频分复用技术的放大转发多中继协同通信系统,提出了基于导频频分复用的频域信道估计算法,包括最小二乘(LS)估计算法和线性最小均方误差(LMMSE)估计算法。理论分析和仿真结果表明,该算法不仅成功分辨了多中继协同通信系统的所有频域信道衰落系数,避免了各中继节点转发的导频符号在目的节点上的混叠干扰,而且减少了频域信道估计所需的导频符号数量和时隙周期长度,提高了协同通信系统的传输效率和频谱利用率,同时显著提高了信道估计的精度,降低了算法的复杂度,具有较高的实用价值。 相似文献
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针对频率选择性衰落信道下的分布式空频编码协同通信系统,提出了基于导频辅助的各种频域信道估计算法,包括最小二乘、线性最小均方误差、低阶近似线性最小均方误差算法,并给出了相应的均方误差性能表达式.理论分析和仿真结果表明本文提出的信道估计算法在协同通信系统中具有很高的实用性和精确度. 相似文献
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在频率选择性衰落信道下的AF多中继无线协作网络中,由于传统的信道估计方法只能估计级联信道的CSI,结合单载波频域均衡技术,提出了一种基于双块导频的分段式频域信道估计方法.双块导频分别由源节点和中继节点做短序列重复变换移位(Short Sequence Repeat Transformation Shift,SSRTS)处理得到,在目的节点结合最小二乘和加窗(Least Squares Windowing,LSW)算法估计出S-R-D信道和R-D信道的CSI,再计算得到S-R信道的CSI.仿真结果表明,该方法可以有效地估计分段信道,提高了信道估计精度,减少了信道训练时隙. 相似文献
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考虑到在复杂街区环境中由于距离太远或者障碍物阻挡等原因,造成源节点和目的节点之间没有直接链路,而是利用多个中继进行协同传输的情景,该文针对放大转发协同OFDM系统,提出了一种时域信道估计算法。不同于传统的频域信道估计,该文利用一种特殊的梳状导频以及在中继节点上对导频做简单变换,通过时域的相关处理估计源节点经每一个中继节点到目的节点之间的等效信道冲激响应。在此基础上,为减小来自中继节点和目的节点的等效噪声对信道估计性能的影响,提出了时域LMMSE(Linear Minimum Mean Square Error)估计以及其简化形式,并推导了相应的Cramér-Rao界(CRB)。仿真结果表明,该文算法具有较好的均方误差性能;与直接时域信道估计相比,该文提出的简化时域LMMSE估计更接近于CRB。 相似文献
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分布式空频编码协同通信系统分段ML迭代检测算法 总被引:1,自引:1,他引:0
该文针对频率选择性衰落下的多中继分布式空频编码协同通信系统,提出了一种分段最大似然迭代检测算法。目的节点将每一个分布式空频编码的频域向量划分成若干小段,分别对其进行最大似然迭代检测。理论分析和仿真结果表明,该迭代最大似然检测算法收敛速度快,且显著降低了分布式空频编码协同通信系统检测算法的复杂度,具有较高的实用价值。 相似文献
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在本文中,考虑了基于分布式频域线性卷积空频码(distributed frequency-domain linear convolutivespace-frequency codes,DFLC-SFC)的协同通信系统。该协同通信系统考虑了多个载波频率偏移(multiple carrierfrequency offsets,MCFOs)的影响,同时假定中继结点到目的结点的信道是平坦衰落的。通过数学推导,该系统模型得到了简化。因此,本文最终得到了等价的限带模型,同时也分析了关于最终等价信道矩阵的限带属性。在此限带模型的基础之上,本文提出了一种应用LDHH矩阵分解的"限带"块最小均方误差(minimum mean square error,MMSE)均衡方法。进一步地,为了实现相应的限带操作,本文还定义了一类特殊的掩码矩阵。相比较于那些传统的MMSE均衡方法,本文所提出的均衡方法在保持较满意的系统性能的前提下,具有相对较低的计算复杂度。 相似文献
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Shuangqing Wei 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2007,53(11):4150-4172
Synchronization of relay nodes is an important and critical issue in exploiting cooperative diversity in wireless networks. In this paper, two asynchronous cooperative diversity schemes are proposed, namely, distributed delay diversity and asynchronous space-time coded cooperative diversity schemes. In terms of the overall diversity-multiplexing (DM) tradeoff function, we show that the proposed independent coding based distributed delay diversity and asynchronous space-time coded cooperative diversity schemes achieve the same performance as the synchronous space-time coded approach which requires an accurate symbol-level timing synchronization to ensure signals arriving at the destination from different relay nodes are perfectly synchronized. This demonstrates diversity order is maintained even at the presence of asynchronism between relay node. Moreover, when all relay nodes succeed in decoding the source information, the asynchronous space-time coded approach is capable of achieving better DM tradeoff than synchronous schemes and performs equivalently to transmitting information through a parallel fading channel as far as the DM tradeoff is concerned. Our results suggest the benefits of fully exploiting the space-time degrees of freedom in multiple antenna systems by employing asynchronous space-time codes even in a frequency-flat-fading channel. In addition, it is shown asynchronous space-time coded systems are able to achieve higher mutual information than synchronous space-time coded systems for any finite signal-to-noise ratio (SNR) when properly selected baseband waveforms are employed. 相似文献
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Space shift keying (SSK) modulation is a scheme in which the indices of active transmit antennas play an essential role in carrying information bits. In SSK modulation, the communication channel acts as modulating unit. Therefore, using the conventional relay selection schemes based on channel coefficients are impossible in cooperative systems using SSK modulation. In this paper, we propose a novel relay selection scheme that is applicable in cooperative systems using SSK modulation. The proposed scheme is based on calculating and measuring the Euclidean distances between received signal and all active or inactive channel coefficients. The proposed relay selection scheme is applied for a cooperative communication system with multiple relay nodes and a direct link between source and destination. The analytical expressions are derived to calculate the average bit error rate over Rayleigh fading channels. The analytical and simulation results show that this relay selection scheme can provide a full cooperative diversity order, for SSK modulation. In addition, we show that this scheme can be used at destination as a signal selection method, to select the best received signal from different paths. The analytical results are validated using Monte Carlo simulation studies. 相似文献
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协同传输作为一种可靠通信技术,通过利用空间分集,能够克服无线通信收发双方经历的信道衰落、噪声干扰、路径损耗等,有效提升系统传输性能。目前有关协同通信技术的基础理论研究较多,但大多数理论研究并没有应用到实际的原理样机中,因此缺少实测数据作为支撑。本文首先设计实现了一种自适应分布式协同传输协议,该协议通过信道感知技术实时获取信道质量信息,自适应地选择协同节点和协同传输方式。通过将所设计的传输协议实现在自主研发的原理样机上,本文从误码率、丢包率和吞吐量三个性能指标上,分别测试了系统在室内、室外、地面、空中等应用场景下的实际传输性能。测试结果表明,相比于传统点对点直传方式,本文所提的自适应分布式协同传输技术能够显著提升节点间的可靠传输性能,实现分布式多节点的自主协同组网通信。 相似文献