针对多输入多输出空间相关信道环境,提出了一种基于格规约理论的最小均方误差检测算法.该算法考虑了空间相关性的影响,利用复数Lenstra-Lenstra-Lovász格规约算法克服了传统的线性最小均方误差检测器分集阶数随相关系数增加而减小的缺点,使检测到的信号在高信噪比下可以达到比传统算法低个数量级的误码率.理论分析与仿真结果表明,在信道为Kronecker相关平坦衰落模型下,接收端采用最小均方误差信道估计,发射端采用QPSK调制未使用信道编码,当比特信噪比大于18dB时,基于格规约理论的最小均方误差检测器的误码率低于传统最小均方误差检测器的误码率 发射端采用(2,1,3)卷积码、接收端采用硬判决Viterbi译码,当信噪比大于16dB时,基于格规约理论的最小均方误差检测器的误码率低于传统最小均方误差检测器的误码率,且基于格规约理论的最小均方误差检测器的分集阶数不受相关系数的影响,等于接收天线数N.
Toovercomethedrawbackthatthediversityorderofthetraditionallinear MMSEdetection
algorithmdecreaseswiththeincreaseofthecorrelationcoefficient,alattice-reduction-aidedMMSE(LRAMMSE)
detectionalgorithmisproposedforspatialcorrelatedMIMOchannels.TheLRA-MMSEdetection
algorithmconsiderstheeffectofspatialcorrelationinthealgorithm designandtakesadvantageofthe
complexLenstra-Lenstra-Lovász(LLL)algorithmsothatitsBER(biterrorrate)isseveralordersof
magnitudesmallerthanthatofthetraditionallinearMMSEdetectionatahighSNR(signaltonoiseratio).
Theoreticalanalysisandsimulationresultsshowthatwith QPSK modulationandthe MMSEchannel
estimatoratthereceiver,theuncodedBERoftheLRA-MMSEdetectorislowerthanthatofthetraditional
linearMMSEdetectorifthebitSNR(Eb/N0)isgreaterthan18dB,whilethecodedBERoftheLRAMMSEdetectorislowerthanthatofthetraditionallinearMMSEdetectorifEb/
N0isgreaterthan16dB
when(2,1,3)convolutionalchannelcodingandViterbidecodingareadoptedundertheKroneckercorrelated
flatfadingchannel.Furthermo (2012-03-22, PDF, 600KB, 下载46次)
MIMO OFDM 技术将成为第4 代移动通信系统的关键技术, 因MIMO OFDM 对时间和频率偏移非常敏感,
因此MIMO OFDM 同步显得尤为重要。提出了一种新的MIMO OFDM 定时同步和频偏同步技术。以GCL 序列为基础设
计了一个新的符合MIMO OFDM 同步技术的导频序列, 通过对该导频序列进行2 次相关得到频率估计, 并将所得频率
运用到定时同步中, 得到更为准确的时间估计。仿真结果表明, 在相同的信噪比情况下, 该方法可以使得系统的误码
率和帧传送误码率相对传统方法得到进一步减小。
MIMO OFDM will become a key technology of the fourth generation mobile communications system. However, MIMO OFDM is
sensitive to the CFO and timing synchronization, so the MIMO OFDM synchronization technology is very important. This paper proposes an
accurate technique for timing and frequency synchronization of multiple input multiple output ( MIMO ) orthogonal frequency division
multiplexing ( OFDM) systems. The technique derives a new preamble signal based on GCL sequences, according with the MIMJO OFDM
synchronization. The carrier frequency offset ( CFO) estimation is obtained through taking double correlation operations on the preamble signal,
and used in the timing synchronization to gain accurate time estimation. The simulation results show that at the same SNR, the proposed method
can reduce the BER and the frame transmission BER of the system compared to the conventional method. (2011-12-11, PDF, 399KB, 下载39次)
多输入多输出(MIMO)通信系统相比其他的通信系统具有更高的频谱效率，在不增加发射功率以及信号带宽的
情况下，MIMO 技术可以有效地提高系统信道容量及其性能。利用均匀角能量分布以及相关矩阵，分析了相关信道下的MIMO
系统信道容量，得出了系统信道容量的通用公式，并利用MATLAB 进行仿真。仿真结果表明，相关性的增加意味着信噪比的减
小，圆形接收天线阵列半径与角度扩展是决定MIMO 系统信道容量的主要因素。
Multiple-input multiple output (MIMO) communication architecture, as compared with conventional
techniques, has even higher spectral efficiency, and MIMO technique could greatly improve channel capacity and
performance of the system without any increase of transmitting power and bandwidth. By uniform angular distribution
and the correlation matrix, the MIMO channel capacity in correlated channel is investigated. Numerical simulation
is performed with MATLAB, thus to verify the proposed formula. Simulation result indicates that, for this model,
the increase of correlation means the reduction of signal-to-noise ratio (SNR), and the circular receive antenna
array radius or angle spread is the dominating factor for channel capacity. (2011-12-11, PDF, 787KB, 下载77次)
随着传输速率越来越高,信号所占用的带宽越来越宽,实际信道呈现出频率选择性衰落特
性。根据频率选择性衰落信道特性,建立了频率选择性衰落M IMO信道模型,采用频域和时域的方
法研究了在频率选择性衰落下,发射端已知和未知信道状态信息的M IMO信道容量,并给出了相关
的仿真结果。研究结果表明:在相同发射功率和传输带宽下,M IMO系统可以不牺牲信号带宽而显
著提高信道的容量,并且天线数量和输入信噪比的大小对信道容量具有不同的影响。研究结果为如
何提高频率选择性衰落环境下M IMO信道容量提供了依据。
With the higher and higher of transmitting rate, the signal bandwidth iswider and wider, and the
p ractical channel p resents the frequency selective fading character. In this paper, a multi- input multi-
output (M IMO) channelmodel under frequency selective fading is constructed according to the character of
frequency selective fading channel. The frequency and time domain methods are used to discussM IMO
channel capacity due to the known and unknown channel state information under the frequency selective fa2
ding. The simulation results show thatM IMO system can imp rove the channel capacity remarkably but no
exchanging signal bandwidth under the circumstances of the same launching power and transmitting band2
width, and the numbers of antennas and the quantity of SNR have the different effect on the channel capaci2
ty. The conclusion offers the basis of how to imp rove M IMO channel capacity under the circumstances of
frequency selective fading. (2011-12-11, PDF, 501KB, 下载55次)
摘 要: 经过限带滤波后的QDPSK 信号的码元波形可分为稳定区与过渡区, 根据这一特点可以利用DFT 方法来实现信
号的解调和位同步。 在这种数字化解调器中需要设计一个合适的带通滤波器, 以便尽可能地消除信号的旁瓣分量而不影响信号
码元稳定区内的波形。本文介绍了上述带通滤波器的方案选择和基于M at lab 的滤波器参数设计方法, 以及仿真效果。
Abs tra c t: A f ter a band pass f ilter, QDPSK signal′ s symbo l can be divided into steady sect i on and t ransit i on sect i on, so the
demodulat i on and synch ronizat i on fo r th is signal can be realized w ith DFT 1 In such a digital demodulato r, it is i mpo r tant to design a
p roper band pass f ilter to get r id of side beam pow er effect ively and don′ t change the w avefo rm in steady sect i on1 Th is paper
int roduces the scheme select i on, parameter design method and si mulate effect fo r th is f ilter based onM at lab1 (2010-05-24, PDF, 193KB, 下载25次)
【摘要】采用’()*(+ 通信仿真软件对应用于无线信道中的,-./，0-./，01(’ 的数字通
信方式和主要通信过程的实际情况进行计算机模拟仿真。主要通信过程为抽样、量化、编码、调制解
调、纠错编码等，并给出了几种调制解调的主要特性，为建立实际通信系统提供了基本的依据。
【关键词】移相键控（-./）；正交幅度调制（1(’）；脉码调制（-2’）
【Abstract】 ()*(+ communication simulation software used in wireless channel in ,-./, 0-. /, 01 ( the number of pass
Letter mode and the actual situation of the main communication process by computer simulation. Main communication process as sampling, quantization, coding, modulation solution
Transfer, error correction coding, etc., and gives the main features of several modulation and demodulation, in order to establish the actual communications system provides the basic basis.
Key words (-./) phase shift keying quadrature amplitude modulation (1 ( ) pulse code modulation (-2 ) (2010-01-19, PDF, 270KB, 下载14次)
由于自适应滤波器组的频率响应匹配于信号的统计特性,所以能够得到更为有效的信号分解. 文中根据信号的统计特性,按照低通子带能量最大化的原理设计自适应滤波器组. 结合自适应滤波器组和传统的阈值方法,得到一种更为有效的去噪方法. 实验结果表明,与相同长度的标准滤波器相比,新方法得到了更大的信噪比改善.
Adaptive filter banks as a result of the frequency response to match the statistical properties of the signal, it can be more effective decomposition of the signal. According to the statistical properties of signals, in accordance with the low-pass sub-band energy to maximize the principle of the design of adaptive filters. combination of adaptive filter and the traditional threshold methods, to be a more effective de-noising method. The experimental results show that the standard with the same filter length, the new methods to improve signal to noise ratio greater. (2009-07-05, PDF, 55KB, 下载4次)