自适应滤波器作为一种现代滤波器，在通信领域有着广泛的应用. 阐述了LMS以及RLS自适应滤波器的相关原理及其在通信系统去噪中的应用，并用MATLAB对自适应滤波器的去噪结果进行了相应的仿真，仿真结果直观地体现了自适应滤波器的去噪性能。
本文对自适应滤波器系统进行剖析，基于QPSK调制后的信号，并对该信号加工成为不同信噪比如SNR=0Db、SNR=5dB、SNR=10dB的信号，进行了两种分别基于LMS自适应滤波和RLS自适应滤波的操作。并对添加了有色高频噪声等加噪处理来模拟通信过程中的实际应用环境，测试所设计的低通滤波器对于噪声信号的滤波性能，并对结果进行分析总结。
As a modern filter, adaptive filter has a wide range of applications in the field of communication. This paper expounds the relevant principles of LMS and RLS adaptive filter and their applications in the de-noising of communication system, and simulates the de-noising results of adaptive filter with MATLAB. The simulation results directly reflect the de-noising performance of adaptive filter.
In this paper, the adaptive filter system is analyzed, based on the QPSK modulated signal, and the signal is processed into different signal-to-noise, such as SNR = 0dB, SNR = 5dB, SNR = 10dB signal. Two kinds of operation are carried out based on LMS adaptive filtering and RLS adaptive filtering respectively. In order to simulate the practical application environment in the communication process, we add colored high-frequency noise to test the filtering performance of the designed low-pass filter for noise signal, and analyze and summarize the results. (2021-02-01, matlab, 3KB, 下载3次)
实现基于STBC的MIMO_OFDM通信系统在不同信噪比情况下接收端的误比特率的仿真。发射端包括基于基带调制、空时编码、导频插入、IFFT、串并合并以及添加循环前缀；接收端包括去除循环前缀、取出导频估计信道、FFT运算以及并串合并，空时解码等。仿真中采用QPSK、空时编码采用4*3的复正交空时编码矩阵。OFDM子载波数为100，每个子载波传输66个符号，每个符号2比特。IFFT长度为512个符号。发射天线为3个接收天线为2个。
The BER simulation of MIMO_OFDM communication system based on STBC under different SNR is realized. The transmitter includes baseband modulation, space-time coding, pilot insertion, IFFT, serial-parallel combination and adding cyclic prefix; the receiver includes removing cyclic prefix, extracting pilot estimation channel, FFT operation, parallel-serial combination, space-time decoding, etc. The complex orthogonal space-time coding matrix is used in QPSK and space time coding in 4*3. The number of OFDM subcarriers is 100, and each subcarrier transfers 66 symbols with 2 bits per symbol. IFFT is 512 symbols in length. The transmitting antenna is 3 receiving antennas, 2. (2018-08-12, matlab, 3KB, 下载32次)
：在长期演进(LTE)系统中，球形译码算法拥有接近于最大似然(ML)的误码率(BER)性能。针对在
16QAM和64QAM等高阶调制情况下球形译码算法计算复杂度和所需硬件资源的急剧增加，提出了一种调整符号搜
索策略的改进型球形译码算法。该算法在不同的检测层采用特定的符号搜索方案，并结合一种基于信噪比的动态调
整半径方法。在无线瑞利信道环境下，对各种球形译码算法进行了仿真。仿真结果表明，提出的改进型算法基本保持
传统球形译码算法较低的BER性能，同时还有效地降低了计算复杂度和硬件实现复杂度。
Motivated by the need for high throughput sphere decoding formultipleinput-
multiple-output (MIMO) communication systems, we propose
a parallel depth-first sphere decoding (PDSD) algorithm that provides
the advantages of both parallel processing and rapid search
space reduction. The PDSD algorithm is designed for efficient implementation
on programmable multi-processor platforms. We investigate
the trade-off between the throughput and computation overhead
when the number of processing elements is 2, 4 and 8, for a 4×
4 16-QAM system across a wide range of SNR conditions. Through
simulation, we show that PDSD can offer significant throughput improvement
without incurring substantial computation overhead by
selecting the appropriate number of processing elements according
to specific SNR conditions (2014-03-23, Visual C++, 144KB, 下载29次)
关键词:FDI,对外直接投资,区位选择,竞争力.中国对外直接投资的区位选择研究分析归纳总结出了中国对外投资存在的区位过分集中，投资规模较小、竞争力差，缺乏宏观引导以及整体投资战略等问题，建议我国企业在认真分析自身优劣势的基础上，制定符合长期发展的全球性战略。同时还要充分考察东道国的投资环境，合理选择投资区位，进一步提高我国对外直接投资的收益率，影响力，建设一批具有国际影响力的跨国公司，进而促进我国经济的发展。
Research on the location choice of foreign direct investment China.The analysis summarized the existing China excessive concentration of foreign investment location, investment scale is smaller, less competitive, the lack of macro guidance and overall investment strategies, the enterprises in China should based on analyzing its advantages and disadvantages, the long-term development of the global strategy. At the same time, fully examine the investment environment of the host country, reasonable choice of investment location, further improve China s foreign direct investment rate of return, influence, the construction of a number of influential international Multi-National Corporation, thereby promoting the economic development of our country. (2013-12-04, Visual C++, 186KB, 下载1次)
根据OFDM的时频特性,提出了一种新的空间测距方法.首先在时域对OFDM信号进行相关处
理,得到距离的粗估计,在粗估计的基础上,利用OFDM不同子载波数据之间的相位差,得到距离的精
确估计,根据精确估计的结果对粗估计的结果进行校正,从而得到最终的距离估计值.仿真结果表明,该
方法的测距精度比采用延迟锁定环的伪码测距方法至少提高了4倍,并且在信噪比大于20 dB时,可以
达到厘米级.
According to the properties of OFDM in the time and frequency domains, a novel ranging
method in space is proposed. The coarse estimation of range can be obtained from the correlation of the
waveforms of OFDM signals in the time domain, and the fine estimation is obtained from the phase
differences between the sub-carriers in the frequency domain. The fine estimation is then adopted to
correct the coarse estimation, and the final estimation of range is achieved. Simulation results show that
the ranging accuracy of the proposed method is more than 4 times better than that of pseudo-code
ranging. Furthermore, the ranging accuracy is close to the centimeter level when the signal-to-noise ratio
is beyond 20 dB.
(2012-11-02, matlab, 55KB, 下载41次)
（1） 分析QPSK调制、解调原理，并画出其系统框图；
（2） 产生等概率且相互独立的二进制序列，作为待传输的信号，并画出其波形；
（3） 进行8PSK调制，分别画出I、Q两支路信号经过乘法器后的波形以及8PSK调制波形；
（4） 产生均值为0，方差为1的加性高斯随机噪声，画出其时域波形及频谱；
（5） 将加性高斯随机噪声作为传输信道的干扰，画出接收端信号的时域图；
（6） 进行8PSK解调，输出解码序列，画出解调后信号波形；
（7） 计算系统信噪比、传输误码率。
(1) analysis of QPSK modulation, demodulation, and draw the system block diagram (2) have equal probability and independent binary sequence as a signal to be transmitted, and draw the waveform and (3) 8PSK modulation, Draw the I, Q two way signal multiplier waveform and 8PSK modulation waveform (4) to produce zero mean and variance of an additive Gaussian random noise, to draw the time-domain waveform and spectrum ( 5) the additive Gaussian random noise interference as a transmission channel, to draw the time-domain diagram of the receiver signal (6) 8PSK demodulator output decoding sequence, draw the demodulation of the signal waveform computing system (7) signal-to-noise ratio, the transmission bit error rate. (2012-06-24, C/C++, 2KB, 下载109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)
针对MIMO-OFDM系统中期望最大化(EM)信道估计算法在高信噪比(SNR)下带来的误差地板(EF)现象,且OFDM符号的数据传输效率随发射天线数的增加而明显降低,提出一种改进的高效EM信道估计算法。该算法首先引入一种准确的等效信号模型并推导出一种修正的EM算法,改善了EM算法在高SNR下的性能 在多个OFDM间利用相位正交导频序列来提高数据传输效率,同时进行联合信道估计以提高估计性能。仿真实验验证了所提算法具有更高的信道估计性能和更高的数据传输效率。
For multiple-input multiple-output with orthogonal frequency division multiplexing(MIMO-OFDM) systems,the error floor(EF) phenomenon at high signal noise rate(SNR) was induced by the expectation maximum(EM) channel estimation algorithm.In addition,the data transmission efficiency was declined obviously with the increasing number of transmit antennas.According to these problems,an improved and efficient EM channel estimation algorithm was pro-posed.Firstly,an accurate and equivalent signal model was introduc... (2011-09-05, matlab, 770KB, 下载59次)
基于期望最大化(EM)的最大后验信道估计算法(MAP)在高信噪比(SNR)下将很难获得较低的估计误差,并且,对于导频辅助的MIMO-OFDM系统,OFDM符号的数据传输效率随着发送天线的增加而明显下降.为改善这两种缺陷,引入一种等效的信号模型来改善高SNR下的估计性能 在相邻多个OFDM符号内使用相移正交导频序列和联合估计来提高系统的数据传输效率和估计性能 根据角域内信道间的独立性来减小噪声对估计的影响.通过仿真实验可知,所提算法具有更小的估计误差和更高的数据传输效率.
Maximum a posteriori(MAP) channel estimation algorithm usually uses expectation maximum(EM) algorithm to decrease the high computation.However,this kind of operation has a difficulty in obtaining ideal estimation performance at high signal to noise ratio(SNR) because of the convergent feature of EM algorithm.In addition,for pilot-based multiple-input multiple-output with orthogonal frequency division multiplexing(MIMO-OFDM) systems,data transmission efficiency of OFDM symbol will be reduced with the increas... (2011-09-05, matlab, 131KB, 下载86次)
本文着重描述了基于CDMA 1 X VPDN网络具体连接建立的步骤和实际应用。提出具体的解决IMSI认证和地址绑定的实现方案，提供了
实验环境拓扑。并给出在试验环境下路由器的基本配置并对主要的配置加以说明。其中lMSI认证实现的关键是利用RAD I US服务器。试验环境使用的软件是FreeRadius免费软件，正式组网时可利用企业现有的RAD I US服务器或安装免费的RAD I US软件，从而低成本解决了该问题。上述解决方案经过实验网测试。系统运行稳定。证明有效可行。
This article focuses on the network based on CDMA 1 X VPDN connection is established specific steps and practical application. IMSI propose specific solutions to achieve certification and address of the binding solution, provides an experimental environment topology. Given in the test environment and the basic configuration of the router' s configuration to illustrate the main. Which is the key to achieving lMSI certified by RAD I US server. The software test environment is FreeRadius using free software can be used when the official network of existing RAD I US enterprise server or install the free RAD I US software, low-cost solutions to the problem. After the experimental network testing solutions. System is stable. Proved effective and feasible. (2011-04-23, Windows_Unix, 344KB, 下载10次)
ITU-T G.722.2
国际电信联盟G.722.2建议书，2003年7月版。该建议书是语音通讯领域的压缩标准，被GSM，WCDMA，3GPP等采用，题目为16kbit下的宽带语音编码，使用自适应多率宽带编码。
内容主要有代数码激励线性预测编码(ACELP)，话音活动检测(VAD)等。
This Recommendation describes the high quality Adaptive Multi-Rate Wideband (AMR-WB)
encoder and decoder that is primarily intended for 7 kHz bandwidth speech signals. AMR-WB
operates at a multitude of bit rates ranging from 6.6 kbit/s to 23.85 kbit/s. The bit rate may be
changed at any 20-ms frame boundary.
Annex C includes an integrated C source code software package which contains the implementation
of the G.722.2 encoder and decoder and its Annexes A and B and Appendix I. A set of digital test
vectors for developers is provided in Annex D. These test vectors are a verification tool providing an
indication of success in implementing this codec.
G.722.2 AMR-WB is the same codec as the 3GPP AMR-WB. The corresponding 3GPP
specifications are TS 26.190 for the speech codec and TS 26.194 for the Voice Activity Detector. (2010-04-21, C/C++, 711KB, 下载117次)
：首先介绍了DS--UWB系统的的发射与接收模型，然后分析了利用滑动相关法对信道进行估讣，并巾此给出
了不同RAKE接收机RAKE合成权系数选取方案。对接收机采用最大比(MRC)、最小均方误差(MM SE)及带均衡
器的(MRC)合并系数选取的误码性能进行了仿真和对比。结果表明了带均衡器的MRC—RAKE只用较少的分支
就可以达到接收性能明显优于MMSE—RAKE的程度。尤其在信噪比比较大时。这种优势更加明显。
: First of all, the introduction of the DS UWB system model of the launch and reception, and then analyzed using the sliding correlation method for estimation of channel obituary, and towels, this gives the RAKE receiver RAKE synthesis of different weights to select the program. On the receiver using maximal ratio (MRC), minimum mean square error (MM SE) and band equalizer (MRC) combined coefficient selected BER simulation and comparison. The results show that the equalizer with MRC-RAKE only with fewer branches on the receiver performance can be achieved significantly better than MMSE-RAKE level. Particularly in the relatively large signal to noise ratio. This advantage becomes even more evident. (2007-10-30, C/C++, 43KB, 下载45次)
：首先介绍了DS--UWB系统的的发射与接收模型，然后分析了利用滑动相关法对信道进行估讣，并巾此给出
了不同RAKE接收机RAKE合成权系数选取方案。对接收机采用最大比(MRC)、最小均方误差(MM SE)及带均衡
器的(MRC)合并系数选取的误码性能进行了仿真和对比。结果表明了带均衡器的MRC—RAKE只用较少的分支
就可以达到接收性能明显优于MMSE—RAKE的程度。尤其在信噪比比较大时。这种优势更加明显。
: First of all, the introduction of the DS UWB system model of the launch and reception, and then analyzed using the sliding correlation method for estimation of channel obituary, and towels, this gives the RAKE receiver RAKE synthesis of different weights to select the program. On the receiver using maximal ratio (MRC), minimum mean square error (MM SE) and band equalizer (MRC) combined coefficient selected BER simulation and comparison. The results show that the equalizer with MRC-RAKE only with fewer branches on the receiver performance can be achieved significantly better than MMSE-RAKE level. Particularly in the relatively large signal to noise ratio. This advantage becomes even more evident. (2007-10-30, C/C++, 148KB, 下载84次)
：首先介绍了DS--UWB系统的的发射与接收模型，然后分析了利用滑动相关法对信道进行估讣，并巾此给出
了不同RAKE接收机RAKE合成权系数选取方案。对接收机采用最大比(MRC)、最小均方误差(MM SE)及带均衡
器的(MRC)合并系数选取的误码性能进行了仿真和对比。结果表明了带均衡器的MRC—RAKE只用较少的分支
就可以达到接收性能明显优于MMSE—RAKE的程度。尤其在信噪比比较大时。这种优势更加明显。
: First of all, the introduction of the DS UWB system model of the launch and reception, and then analyzed using the sliding correlation method for estimation of channel obituary, and towels, this gives the RAKE receiver RAKE synthesis of different weights to select the program. On the receiver using maximal ratio (MRC), minimum mean square error (MM SE) and band equalizer (MRC) combined coefficient selected BER simulation and comparison. The results show that the equalizer with MRC-RAKE only with fewer branches on the receiver performance can be achieved significantly better than MMSE-RAKE level. Particularly in the relatively large signal to noise ratio. This advantage becomes even more evident. (2007-10-30, C/C++, 203KB, 下载276次)