介绍

LTE工具箱可用于生成标准的基带智商下行测试模型（E-TM）波形以及上行链路和下行链路参考测量通道（RMC）波形。将LTE工具箱与仪器控制工具箱allows LTE waveforms created in MATLAB® to be used with test and measurement hardware. Waveforms created by the LTE Toolbox can be modulated for transmission using a signal generator. Waveforms captured using a signal analyzer can be analyzed using MATLAB and LTE Toolbox functions.

In this example the Instrument Control Toolbox is used to interface with an RF signal generator and analyzer. An E-TM waveform, synthesized in MATLAB using the LTE Toolbox, is downloaded to a Keysight Technologies N5172B signal generator for over-the-air transmission. The over-the-air signal is captured using a Keysight Technologies N9010A signal analyzer and retrieved into MATLAB for analysis.

可以使用LTE工具箱分析捕获的波形，如以下示例所示：

This example illustrates how external test and measurement equipment can be used to analyze the received waveform; in this case Keysight Technologies Vector Signal Analysis (VSA) software is also used.

Generate a Baseband Waveform Using the LTE Toolbox

LTE工具箱提供了GUIS和功能，可根据[1]。lteTestModelToolcan be used to configure and create the signal using a GUI.

或者，功能lteTestModelandlteTestModelToolallow the programmatic configuration and generation of LTE test models and baseband IQ waveforms.

config = ltetestmodel（'1.1','5MHz'）；% Test Model 1.1, 5MHz bandwidthconfig.TotSubframes = 100;% Generate 100 subframes[waveform, tmgrid, config] = lteTestModelTool(config);

有关LTE测试模型信号的更多详细信息，请参阅随附的LTE Downlink Test Model (E-TM) Waveform Generation例子。

生成的时间域波形的频谱，波形，可以使用DSP系统工具箱dsp.SpectrumAnalyzerobject. As expected, the 5MHz signal bandwidth is clearly visible at baseband.

% Calculate the spectral content in the LTE signalspectrumplottx = dsp.spectrumanalyzer;spectrumplottx.samplerate = config.samplingrate;spectrumplottx.spectrumtype =“功率密度”;spectrumplottx.powerunits ='dBm';spectrumplottx.rbwsource ='财产';spectrumplottx.rbw = 15e3;spectrumplottx.frequencyspan =“跨度和中心频率”;spectrumplottx.span = 7.68e6;spectrumplottx.centerfquency = 0;spectrumplottx.window ='Rectangular';spectrumPlotTx.SpectralAverages = 10; spectrumPlotTx.YLimits = [-100 -60]; spectrumPlotTx.YLabel ='PSD';spectrumplottx.title =“测试模型E-TM1.1，5 MHz信号频谱”;spectrumPlotTx.ShowLegend = false; spectrumPlotTx(waveform);

使用RF信号发生器生成空中信号

The Instrument Control Toolbox is used to download and play the test model waveform created by the LTE Toolbox,波形，使用Keysight Technologies N5172B信号发生器。这会产生一个RF LTE信号，中心频率为1GHz。注意1GHz被选为示例频率，并且不打算作为公认的LTE通道。

% Download the baseband IQ waveform to the instrument. Generate the RF% signal at a center frequency of 1GHz and output power of 0dBm.电源= 0;％ 输出功率loopcount = inf;% Number of times to loop％配置信号发生器，下载波形和循环rf = rfsiggen('tcpip0 :: a-n5172b-50283.dhcp.mathworks.com :: inst0 :: instr'）；download(rf,waveform.',config.SamplingRate); start(rf,1e9,power,loopCount);

Inspect the RF signal generator objectrfsiggen（仪器控制工具箱）for more details on the commands used to download and play the waveform.

可以使用调谐到1GHz中心频率的频谱分析仪查看信号发生器传输的RF信号的频谱。下面的屏幕截图，来自Keysight Technologies N9010A信号分析仪，清楚地显示了5MHz信号带宽。

从标记获得MATLAB的基带信号l Analyzer

在MATLAB分析无线传输, the Instrument Control Toolbox is used to configure the Keysight Technologies N9010A signal analyzer and capture baseband IQ data. The helper functionhcaptureiqusingn9010a.mretrieves the baseband IQ data,IQData, and the sample rate,采样率, from the signal analyzer, ready for analysis in MATLAB.

[iqdata，采样] = hcaptureiqusingn9010a（...'A-N9010A-21026.dhcp.mathworks.com'，config.totsubframes*1e-3，...1E9，5E6，false，990E6，1010E6，200E3，200E3）;

Inspect the functionhcaptureiqusingn9010a.m有关输入参数的更多详细信息以及配置Keysight Technologies N9010A信号分析器并检索数据所需的命令。

当完成传输和接收时，请停止波形输出stop(rf); disconnect(rf); clearrf;

Once the captured baseband IQ data,IQData，使用仪表控制工具箱从信号分析仪中获取到MATLAB，可以使用LTE Toolbox，Communications Toolbox™和DSP System Toolbox在MATLAB内的数据上立即执行自定义可视化，分析和解码。数据也可以存储在MATLAB中的DATA分析中的垫子文件中。在此示例中，基带智商数据和系统参数一起存储在MAT文件中，可与Keysight Technologies VSA软件一起使用。

注意仪器硬件返回的采样率与配置的采样率不同。返回的采样率对于使用Keysight Technologies VSA软件的测量有效，但是实际信号解码将需要重新采样获得的数据。

％垫子文件接口参数freqvalidmax = 1.010e9;freqvalidmin = 9.90E8;inputCenter = 1E9;xdelta = 1/采样;y = iqdata;固定值的百分比集合IQ = 0; InputRefImped = 50; InputZoom = 1; XDomain = 2; XStart = 0; XUnit ='sec';YUnit ='v';% Save the variables for subsequent up-loading into VSA.save('downlinktestmodel1p1fdd5mhz_rx.mat','freqvalidmax','FreqValidMin',...'IQ',“输入中心”,“ inputrefimped','InputZoom','XDelta',...'Xdomain','XStart','XUnit','y','YUnit'）；

绘制检索到的时域基带波形的频谱，Y, using thedsp.SpectrumAnalyzerobject shows the expected 5MHz occupied bandwidth, with impairments due to RF transmission and reception.

spectrumplotrx = dsp.spectrumanalyzer;spectrumplotrx.samplerate = 1/xdelta;spectrumplotrx.spectrumtype =“功率密度”;spectrumPlotRx.PowerUnits ='dBm';spectrumPlotRx.RBWSource ='财产';spectrumplotrx.rbw = 15e3;spectrumplotrx.frequencyspan =“跨度和中心频率”;spectrumPlotRx.Span = 7.68e6; spectrumPlotRx.CenterFrequency = 0; spectrumPlotRx.Window ='Rectangular';spectrumPlotRx.SpectralAverages = 10; spectrumPlotRx.YLabel ='PSD';spectrumPlotRx.Title =“接收信号频谱：E-TM1.1，5 MHz';spectrumPlotRx.ShowLegend = false; spectrumPlotRx(Y); release(spectrumPlotRx)

分析接收的LTE信号

可以使用LTE工具箱分析捕获的波形，如以下示例所示：

The MAT file containing the retrieved data is loaded into Keysight Technologies VSA software and LTE specific measurement are made. The screenshots of the interactive displays from the VSA software confirms the waveform characteristics of the E-TM1.1 test model in terms of the occupied bandwidth, number of resource blocks used per channel and signal, their corresponding power levels and low EVM values.

Appendix

This example uses this helper function.

选定的参考书目