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1xEV-DO Waveform Generation

This example shows how to generate standard-compliant forward (downlink) and reverse (uplink) 1xEV-DO waveforms using the Communications System Toolbox™.

Introduction

The Communications System Toolbox can be used to generate preset or customized standard-compliant forward and reverse, Release 0 and Revision A 1xEV-DO waveforms.

The generated waveforms can be used for the following applications:

  • Golden reference for transmitter implementations

  • Receiver testing and algorithm development

  • Testing RF hardware and software

  • Interference testing

Waveform Generation Techniques

  • Waveforms can be generated using the evdoForwardWaveformGenerator and evdoReverseWaveformGenerator functions. The input of these functions is a structure containing top-level waveform parameters as well as substructures containing channel- or packet-specific parameters. This example will illustrate how such structures can be constructed from scratch.

  • Preset structure configurations can be created using the evdoForwardReferenceChannels and evdoReverseReferenceChannels functions. Such preset configurations can represent common Test and Measurement scenarios or provide a good starting point (wizard) for customizing a waveform configuration.

Generation of Preset-driven Forward and Reverse 1xEV-DO Waveforms

The preset structure configurations can then be passed to the waveform generation functions. For example, the following commands generate Revision A and Release 0 forward and reverse waveforms, respectively.

forwardPresetConfig = evdoForwardReferenceChannels('RevA-5120-2-64', 10);
forwardPresetWaveform = evdoForwardWaveformGenerator(forwardPresetConfig);

reversePresetConfig = evdoReverseReferenceChannels('Rel0-38400', 10);
reversePresetWaveform = evdoReverseWaveformGenerator(reversePresetConfig);

Generation of a Forward 1xEV-DO Waveform Using Full Parameter List

Next, we illustrate the creation of equivalent configuration structures from scratch. This is also useful for customizing the preset configurations.

% Create top-level waveform parameters:
fManualConfig.Release = 'RevisionA';            % 'Release0' or 'RevisionA'
fManualConfig.PNOffset = 0;                     % PN Offset of the Base station
fManualConfig.IdleSlotsWithControl = 'Off';
fManualConfig.EnableControl = 'On';
fManualConfig.OversamplingRatio = 4;            % Upsampling factor
fManualConfig.FilterType = 'cdma2000Long';      % Filter coefficients: 'cdma2000Long', 'cdma2000Short', 'Custom' or 'Off'
fManualConfig.InvertQ = 'Off';                  % Negate the imaginary output
fManualConfig.EnableModulation = 'Off';         % Enable modulation
fManualConfig.ModulationFrequency = 0;          % Modulation frequency (Hz)
fManualConfig.NumChips = 41600;                 % Number of chips in the waveform

% Create a input message source for the packets:
pds.MACIndex = 0;                               % MAC index associated with data
pds.DataSource = {'PN9', 1};                    % Input message: {'PNX', Seed} or numerical vector
pds.EnableCoding = 'On';                        % Enable channel coding
fManualConfig.PacketDataSources = pds;          % Add the data source specification to the waveform configuration

% Create a single packet:
fPacket.MACIndex = 0;                           % MAC index associated with this packet
fPacket.PacketSize = 5120;                      % The packet size: 128, 256, 512, 1024, 2048 4096 or 5120 bits
fPacket.NumSlots = 2;                           % The number of slots: 1, 2, 4, 8 or 16
fPacket.PreambleLength = 64;                    % The preamble length: 64, 128, 256, 512 or 1024 chips
% Create a sequence of 10 packets:
fManualConfig.PacketSequence = repmat(fPacket, 1, 10);

% Generate waveform:
forwardManualWaveform = evdoForwardWaveformGenerator(fManualConfig);

% Demonstrate that the above two parameterization approaches are equivalent:
if(isequal(forwardPresetConfig, fManualConfig))
    disp([  'Configuration structures generated with and without the ' ...
            'evdoForwardReferenceChannels function are the same.']);
end
Configuration structures generated with and without the evdoForwardReferenceChannels function are the same.

Generation of a Reverse 1xEV-DO Waveform Using Full Parameter List

% Create top-level waveform parameters:
rManualConfig.Release = 'Release0';             % 'Release0' or 'RevisionA'
rManualConfig.LongCodeMaskI = 0;                % Initial long code mask for I channel
rManualConfig.LongCodeMaskQ = 0;                % Initial long code mask for Q channel
rManualConfig.OversamplingRatio = 4;            % Upsampling factor
rManualConfig.FilterType = 'cdma2000Long';      % Filter coefficients: 'cdma2000Long', 'cdma2000Short', 'Custom' or 'Off'
rManualConfig.InvertQ = 'Off';                  % Negate the imaginary output
rManualConfig.EnableModulation = 'Off';         % Enable modulation
rManualConfig.ModulationFrequency = 0;          % Modulation frequency (Hz)
rManualConfig.NumChips = 327680;                % Number of chips in the waveform

% Create a single packet:
rPacket.Power = 0;                              % Relative channel power (dBW)
rPacket.DataSource = {'PN9', 1};                % Input message: {'PNX', Seed} or numerical vector
rPacket.EnableCoding = 'On';                    % Enable channel coding
rPacket.DataRate = 38400;                       % Data rate (bps)
% Create a sequence of 10 packets:
rManualConfig.PacketSequence = repmat(rPacket, 1, 10);

% Add a Pilot Channel:
pich.Enable = 'On';                             % Enable the pilot channel
pich.Power = 0;                                 % Relative channel power (dBW)
pich.DataSource = {'PN9', 1};                   % Input message: {'PNX', Seed} or numerical vector
pich.EnableCoding = 'On';                       % Enable channel coding
rManualConfig.PilotChannel = pich;              % Add the channel to the waveform configuration

% Add an ACK Channel, but do not enable it:
ach.Enable = 'Off';                             % Do not enable the ack channel
ach.Power = 0;                                  % Relative channel power (dBW)
ach.DataSource = {'PN9', 1};                    % Input message: {'PNX', Seed} or numerical vector
rManualConfig.ACKChannel = ach;                 % Add the disabled channel specification to the waveform configuration

% Generate waveform:
reverseManualWaveform   = evdoReverseWaveformGenerator(rManualConfig);

% Demonstrate that the above two parameterization approaches are equivalent:
if(isequal(reversePresetConfig, rManualConfig))
    disp([  'Configuration structures generated with and without the ' ...
            'evdoForwardReferenceChannels function are the same.']);
end
Configuration structures generated with and without the evdoForwardReferenceChannels function are the same.

Waveform Comparison

Compare the waveforms generated using both approaches described above and see that the generated waveforms are identical

if(isequal(forwardPresetWaveform, forwardManualWaveform))
    disp([  'Forward waveforms generated with and without the ' ...
            'evdoForwardReferenceChannels function are the same.']);
end

if(isequal(reversePresetWaveform, reverseManualWaveform))
    disp([  'Reverse waveforms generated with and without the ' ...
            'evdoReverseReferenceChannels function are the same.']);
end
Forward waveforms generated with and without the evdoForwardReferenceChannels function are the same.
Reverse waveforms generated with and without the evdoReverseReferenceChannels function are the same.

Customizing Configurations

The configuration structures can be customized in order to create a waveform that better suits your objective. For example:

rManualConfig2 = rManualConfig;
rPacket.Power = -10;                            % Relative channel power (dBW)
rPacket.DataSource = {'PN23', 1};               % Input message: {'PNX', Seed} or numerical vector
rPacket.EnableCoding = 'Off';                   % Enable channel coding
rPacket.DataRate = 38400;                       % Data rate (bps)
rManualConfig2.PacketSequence = repmat(rPacket, 1, 10);

% Regenerate the waveform accounting for the customizations:
reverseManualWaveform2   = evdoReverseWaveformGenerator(rManualConfig2);

Plot Spectrum of Generated 1xEV-DO Waveforms

chiprate = 1.2288e6;   % Chip rate of the baseband waveform (SR1)
spectrumPlot = dsp.SpectrumAnalyzer('SampleRate', chiprate*fManualConfig.OversamplingRatio);
spectrumPlot.Title = 'Spectrum of Forward 1xEV-DO Waveform';
spectrumPlot.YLimits = [-180,40];
spectrumPlot(forwardManualWaveform);

spectrumPlot2 = dsp.SpectrumAnalyzer('SampleRate', chiprate*rManualConfig.OversamplingRatio);
spectrumPlot2.Title = 'Spectrum of Reverse 1xEV-DO Waveform';
spectrumPlot2.YLimits = [-180,40];
spectrumPlot2(reverseManualWaveform2);

Selected Bibliography

  1. C.S0024-A v3.0: cdma2000 High Rate Packet Data Air Interface Specification.

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