TDSCDMA_DnLnk_TX

This section provides parameter information for Required Parameters, Basic Parameters, Signal Parameters, and parameters for the various measurements.

Symbol


Description TD-SCDMA downlink TX test
Library WTB
Class TSDFTDSCDMA_DnLnk_TX
Derived From baseWTB_TX

Parameters

Name Description Default Sym Unit Type Range
RequiredParameters            
CE_TimeStep Circuit envelope simulation time step 1/1.28 MHz/8   sec real (0, ∞)
WTB_TimeStep Set CE_TimeStep < = 1/1.28e6/SamplesPerChip.        
FSource Source carrier frequency 1900 MHz   Hz real (0, ∞)
SourcePower Source power dbmtow(-20.0)   W real [0, ∞)
FMeasurement Measurement carrier frequency 1900 MHz   Hz real (0, ∞)
MeasurementInfo Available Measurements        
RF_EnvelopeMeasurement Enable RF envelope measurement? NO, YES YES     enum  
Constellation Enable constellation measurement? NO, YES NO     enum  
PowerMeasurement Enable power measurement? NO, YES NO     enum  
SpectrumMeasurement Enable spectrum measurement? NO, YES NO     enum  
EVM_Measurement Enable EVM measurement? NO, YES NO     enum  
BasicParameters            
SourceR Source resistance 50 Ohm   Ohm real (0, ∞)
SourceTemp Source resistor temperature -273.15   Celsius real [-273.15, ∞)
EnableSourceNoise Enable source thermal noise? NO, YES NO     enum  
MeasR Measurement resistance 50 Ohm   Ohm real [10, 1.0e6]
MirrorSourceSpectrum Mirror source spectrum about carrier? NO, YES NO     enum  
MirrorMeasSpectrum Mirror meas spectrum about carrier? NO, YES NO     enum  
RF_MirrorFreq Mirror source frequency for spectrum/envelope measurement? NO, YES NO     enum  
MeasMirrorFreq Mirror meas frequency for spectrum/envelope measurement? NO, YES NO     enum  
TestBenchSeed Random number generator seed 1234567     int [0, ∞)
SignalParameters            
GainImbalance Gain imbalance, Q vs I 0.0   dB real (-∞, ∞)
PhaseImbalance Phase imbalance, Q vs I 0.0   deg real (-∞, ∞)
I_OriginOffset I origin offset (percent) 0.0     real (-∞, ∞)
Q_OriginOffset Q origin offset (percent) 0.0     real (-∞, ∞)
IQ_Rotation IQ rotation 0.0   deg real (-∞, ∞)
SamplesPerChip Samples per chip 8 S   int [2, 32]
RRC_FilterLength RRC filter length (chips) 8     int [2, 128]
MidambleAllocScheme Midamble allocation scheme: UE_Specific, Common, Default Common     enum  
BasicMidambleID Basic midamble index 0     int [0, 127]
MidambleID1 1st DPCH midamble index 1     int [1, K]
MidambleID2 2nd DPCH midamble index 2     int [1, K]
MaxMidambleShift Max midamble shift 16 K   int [1, 16]
ActiveTimeslot Active Timeslot: TS0, TS2, TS3, TS4, TS5, TS6 TS2     enum  
SpreadCode1 1st DPCH spread code index 1     int [1, 16]
SpreadCode2 2nd DPCH spread code index 2     int [1, 16]
DownlinkPilotCode Downlink pilot code index 0     int [0, 31]
ModPhase Modulation phase quadruples: S1, S2 S1     enum  
DwPCH_Gain DwPCH gain 1     int (0, ∞)
RF_EnvelopeMeasurementParameters            
RF_EnvelopeDisplayPages RF envelope measurement display pages:        
RF_EnvelopeStart RF envelope measurement start 0.0   sec real [0, ∞)
RF_EnvelopeStop RF envelope measurement stop 5.0 msec   sec real [0, ∞)
RF_EnvelopeSubframes RF envelope measurement subframes 1     int [0, 100]
ConstellationParameters            
ConstellationDisplayPages Constellation measurement display pages:        
ConstellationSubframes Constellation measurement subframes 3     int [1, 100]
PowerMeasurementParameters            
PowerDisplayPages Power measurement display pages:        
PowerSubframeMeasured Subframes measured 3     int [1, ∞)
SpectrumMeasurementParameters            
SpecMeasDisplayPages Spectrum measurement display pages:        
SpecMeasStart Spectrum measurement start 0.0   sec real [0, ∞)
SpecMeasStop Spectrum measurement stop 5.0 msec   sec real [0, ∞)
SpecMeasSubframes Spectrum measurement subframes 3     int [0, 100]
SpecMeasResBW Spectrum resolution bandwidth 0   Hz real [0, ∞)
SpecMeasWindow Window type: none, Hamming 0.54, Hanning 0.50, Gaussian 0.75, Kaiser 7.865, _8510 6.0, Blackman, Blackman-Harris none     enum  
EVM_MeasurementParameters            
EVM_DisplayPages EVM measurement display pages:        
EVM_StartTime EVM measurement start 0.0   sec real [0, ∞)
EVM_AverageType Average type: Off, RMS (Video) RMS (Video)     enum  
EVM_SubframesToAverage Subframes used for RMS averaging 3     int [1, ∞)
EVM_ActiveSlotThreshold Active slot threshold (dBc) -30.0     real [-120, 0]
SignalToESG_Parameters            
EnableESG Enable signal to ESG? NO, YES NO     enum  
ESG_Instrument ESG instrument address [GPIB0::19::INSTR][localhost][4790]     instrument  
ESG_Start Signal start 0.0   sec real [0, ∞)
ESG_Stop Signal stop 5.0 msec   sec real [(ESG_Start+60/1.28e6/S), (ESG_Start+32/1.28/S)]
ESG_Subframes Subframes to ESG 3     int [0, 1000]
ESG_Power ESG RF ouput power (dBm) -20     real (-∞, ∞)
ESG_ClkRef Waveform clock reference: Internal, External Internal     enum  
ESG_ExtClkRefFreq External clock reference freq 10 MHz   Hz real (0, ∞)
ESG_IQFilter IQ filter: through, filter_2100kHz, filter_40MHz through     enum  
ESG_SampleClkRate Sequencer sample clock rate 10.24 MHz   Hz real (0, ∞)
ESG_Filename ESG waveform storage filename TDSCDMA_DL     string  
ESG_AutoScaling Activate auto scaling? NO, YES YES     enum  
ESG_ArbOn Select waveform and turn ArbOn after download? NO, YES YES     enum  
ESG_RFPowOn Turn RF ON after download? NO, YES YES     enum  
ESG_EventMarkerType Event marker type: Neither, Event1, Event2, Both Event1     enum  
ESG_MarkerLength ESG marker length 10     int [1, 60]

Pin Inputs

Pin Name Description Signal Type
2 Meas_In Test bench measurement RF input from RF circuit timed

Pin Outputs

Pin Name Description Signal Type
1 RF_Out Test bench RF output to RF circuit timed

Setting Parameters

More control of the test bench can be achieved by setting parameters on the Basic Parameters, Signal Parameters, and measurement categories for the activated measurements.

Note
For required parameter information, see TDSCDMA_DnLnk_TX.

Basic Parameters

  1. SourceR is the RF output source resistance.
  2. SourceTemp is the RF output source resistance temperature (oC) and sets noise density in the RF output signal to (k(SourceTemp+273.15)) Watts/Hz, where k is Boltzmann's constant.
  3. EnableSourceNoise, when set to NO disables the SourceTemp and effectively sets it to -273.15oC (0 Kelvin). When set to YES, the noise density due to SourceTemp is enabled.
  4. MeasR defines the load resistance for the RF DUT output Meas signal into the test bench. This resistance loads the RF DUT output; it is also the reference resistance for Meas signal power measurements.
  5. MirrorSourceSpectrum is used to invert the polarity of the Q envelope of the generated RF signal before it is sent to the RF DUT. Depending on the configuration and number of mixers in an RF transmitter, the signal at the input of the DUT may need to be mirrored. If such an RF signal is desired, set this parameter to YES.
  6. MirrorMeasSpectrum is used to invert the polarity of the Q envelope in the Meas_in RF signal input to the test bench (and output from the RF DUT). Depending on the configuration and number of mixers in the RF DUT, the signal at its output may be mirrored compared to the signal generated by the signal source (before any mirroring is done because of the MirrorSourceSpectrum setting). Proper demodulation and measurement of the RF DUT output signal requires that its RF envelope is not mirrored compared to the signal generated by the signal source (before any mirroring is done because of the MirrorSourceSpectrum setting). If the Meas_in RF signal is mirrored, set this parameter to YES. Proper setting of this parameter is required for measurements on the Meas_in signal in TX test benches (EVM, Constellation, CDP, PCDE) and results in measurement on a signal with no spectrum mirroring.
  7. TestBenchSeed is an integer used to seed the random number generator used with the test bench. This value is used by all test bench random number generators, except those RF DUT components that use their own specific seed parameter. TestBenchSeed initializes the random number generation. The same seed value produces the same random results, thereby giving you predictable simulation results. To generate repeatable random output from simulation to simulation, use any positive seed value. If you want the output to be truly random, enter the seed value of 0.
  8. RF_MirrorFreq is used to invert the polarity of the Q envelope in the RF_out RF signal for RF envelope, ppectrum, ACLR, and occupied bandwidth measurements. RF_MirrorFreq is typically set by the user to NO when MirrorSourceSpectrum = NO; RF_MirrorFreq is typically set by the user to YES when MirrorSourceSpectrum = YES. Both settings result in viewing the RF_out signal with no spectrum mirroring. Other settings by the user result in RF_out signal for RF_Envelope and Spectrum measurements with spectrum mirroring.
  9. MeasMirrorFreq is used to invert the polarity of the Q envelope in the Meas_in RF signal for the RF envelope, spectrum, ACLR, and occupied bandwidth measurements.
    MeasMirrorFreq is typically set to NO by the user when the combination of the MirrorSourceSpectrum value and any signal mirroring in the users RF DUT results in no spectrum mirroring in the Meas_in signal. MeasMirrorFreq is typically set to YES by the user when the combination of the MirrorSourceSpectrum and RF DUT results in spectrum mirroring in the Meas_in signal.
    Other settings result in Meas_in signal for RF_Envelope and Spectrum measurements with spectrum mirroring. The MirrorMeasSpectrum parameter setting has no impact on the setting or use of the MeasMirrorFreq parameter.

Signal Parameters

  1. GainImbalance, PhaseImbalance, I_OriginOffset, Q_OriginOffset, and IQ_Rotation are used to add certain impairments to the ideal output RF signal. Impairments are added in the order described here.
    The unimpaired RF I and Q envelope voltages have gain and phase imbalance applied. The RF is given by:

    where A is a scaling factor that depends on the SourcePower and SourceR parameters specified by the user, V I ( t ) is the in-phase RF envelope, V Q ( t ) is the quadrature phase RF envelope, g is the gain imbalance

    and, φ (in degrees) is the phase imbalance.
    Next, the signal V RF ( t ) is rotated by IQ_Rotation degrees. The I_OriginOffset and Q_OriginOffset are then applied to the rotated signal. Note that the amounts specified are percentages with respect to the output rms voltage. The output rms voltage is given by sqrt(2 × SourceR × SourcePower).
  2. SamplesPerChip sets the number of samples in a chip.
    The default value is set to 8 to display settings according to the 3GPP NTDD. It can be set to a larger value for a simulation frequency bandwidth wider than 8 × 1.28 MHz. It can be set to a smaller value for faster simulation; however, this will result in lower signal fidelity. If SamplesPerChip = 8, the simulation RF bandwidth is larger than the signal bandwidth by a factor of 8 (e.g., simulation RF bandwidth = 8 × 1.28 MHz).
  3. RRC_FilterLength sets root raised-cosine (RRC) filter length in chips.
    The default value is set to 8 to transmit TD-SCDMA downlink signals in time and frequency domains based on the 3GPP NTDD standard [1]-[3]. It can be set to a smaller value for faster simulation; however, this will result in lower signal fidelity.
  4. MidambleAllocScheme is used to select the midamble allocation scheme. There are three midamble allocation schemes based on the 3GPP NTDD standard [1], [2]. To set the MidambleAllocScheme parameter based on the 3GPP NTDD standard [1], related parameters must be set as stated here.
    • UE specific midamble allocation : a UE specific midamble for uplink and downlink is explicitly assigned by higher layers.
      if MidambleAllocScheme=UE_Specific, BasicMidambleID, MaxMidambleShift, and MidambleID are used to specify which midamble is exported.
    • Common midamble allocation : the midamble for downlink is allocated by layer 1 depending on the number of channelization codes currently present in the downlink time slot.
      if MidambleAllocScheme=Common, only BasicMidambleID and MaxMidambleShift are used to specify which midamble is exported; the MidambleID parameter is ignored.
    • Default midamble allocation : the midamble for uplink and downlink is assigned by layer 1 depending on the associated channelization code.
      if MidambleAllocScheme=Default, only BasicMidambleID and MaxMidambleShift are used to specify which midamble is exported; the MidambleID parameter is ignored.
  5. BasicMidambleID sets the basic midamble code ID. The basic midamble code is used for training sequences for uplink and downlink channel estimation, power measurements and maintaining uplink synchronization. There are 128 different sequences; the BasicMidambleID range is 0 to 127. In Signal Studio, Basic Midamble ID code has the same meaning as this parameter.
  6. MidambleID1 and MidambleID2 set the midamble indices for the first and second DPCH, respectively. Midambles of different users active in the same cell and the same time slot are cyclically shifted versions of one basic midamble code.
    Let P = 128, the length of basic midamble and K=MaxMidambleShift, then
    W = , is the shift between midambles and
    denotes the largest number less than or equal to x. The MidambleID range is from 1 to MaxMidambleShift.
    MidambleID and MaxMidambleShift together correspond to the Midamble Offset parameter in Signal Studio for Timeslot setup. Midamble Offset = MidambleID × W.
  7. MaxMidambleShift is the maximum number of different midamble shifts in a cell that can be determined by maximum users in the cell for the current time slot.
  8. ActiveTimeslot specifies which slot signal in the subframe will be transmitted. Referring to 12.2 kbps Downlink Channel Subframe Structure, when ActiveTimeslot=2, TS2 is used.
  9. SpreadCode1 and SpreadCode2 set spread code indices for the first and second DPCH, respectively. For this signal source, the spreading factor is 16.
    In Signal Studio, channelization code for time slot setup has the same meaning as SpreadCode1 and SpreadCode2.
  10. DownlinkPilotCode sets the downlink pilot synchronization sequence (SYNC-DL). Downlink pilot synchronization is used for DL synchronization and cell initial search. 32 different SYNC-DL code groups are used to distinguish base stations.
    DwPTS has 64 chips of a complex SYNC_DL sequence

    and 32 chips of guard period. To generate the complex SYNC_DL code, the basic SYNC_DL code s = s 1 , s 2 , ... , s 64 is used. There are 32 different basic SYNC_DL codes for the entire system. The relation between s and s-is given by:

    Therefore, the elements are alternating real and imaginary.
    In Signal Studio, SYNC Code is used to set the downlink pilot code.
  11. ModPhase is used to select the phase quadruples of DwPTS for various phase rotation patterns. In Signal Studio, the Rotation Phase parameter is used to select the phase quadruples.
    Two different phase quadruples S1 and S2 are specified by 3GPP NTDD standard [3] and described in the following table. A quadruple always starts with an even signal frame number.
    Name Phase Quadruple Description
    S1 135, 45, 225, 135 A P-CCPCH is present in the next 4 sub-frames
    S2 315, 225, 315, 45 A P-CCPCH is not present in the next 4 sub-frames
  12. DwPCH_Gain sets the gain of DwPCH relative to DPCH. In Signal Studio, there are dialog boxes with dB unit for each DwPCH to set the gain of DwPCH relative to DPCH.

RF Envelope Measurement Parameters

The RF Envelope measurement is not affected by the MirrorMeasSpectrum parameter. To apply spectrum mirroring to the measured RF_out signal, set RF_MirrorFreq=YES. To apply spectrum mirroring to the measured Meas_in signal, set MeasMirrorFreq=YES.

Constellation Parameters

The Constellation measurement requires setting the MirrorMeasSpectrum parameter such that there is an even number of spectrum mirrorings from the combined test bench source and RF DUT. For example, if MirrorSourceSpectrum=NO and the RF DUT causes its output RF signal to have spectrum mirroring relative to its input signal, then set MirrorMeasSpectrum=YES.

  1. ConstellationDisplayPages provides Data Display page information for this measurement. It cannot be changed by the user.
  2. ConstellationSubframes sets the number of subframes over which data will be collected.
  3. The measurement start time is the time when the first subframe is detected in the measured RF signal. Automatic synchronization by the measurement model avoids any start-up transient in the Constellation plots.

Power Measurement Parameters

  1. PowerDisplayPages provides Data Display page information for this measurement. It cannot be changed by the user.
  2. PowerSubframeMeasured sets the number of subframes over which data will be collected.
  3. The measurement start time is the time when the first subframe is detected in the measured RF signal. Automatic synchronization by the measurement model avoids any start-up transient in the Constellation plots. The measurement stop time is this start time plus PowerSubframeMeasured × SubframeTime. SubframeTime is described in Test Bench Variables for Data Displays.

Spectrum Measurement Parameters

The Spectrum measurement calculates the spectrum of the input signal. Averaging the spectrum over multiple subframes can be enabled as described in this section.
This measurement is not affected by the MirrorMeasSpectrum parameter. To apply spectrum mirroring to the measured RF_out signal, set RF_MirrorFreq = YES; to apply spectrum mirroring to the measured Meas_in signal, set MeasMirrorFreq = YES.
In the following, TimeStep denotes the simulation time step and FMeasurement denotes the measured RF signal characterization frequency.

  1. The measurement outputs the complex amplitude voltage values at the frequencies of the spectral tones. It does not output the power at the frequencies of the spectral tones. However, one can calculate and display the power spectrum as well as the magnitude and phase spectrum by using the dBm, mag, and phase functions of the data display window.
    Note that the dBm function assumes a 50-ohm reference resistance; if a different measurement was used in the test bench, its value can be specified as a second argument to the dBm function, for example, dBm(SpecMeas, Meas_RefR) where SpecMeas is the instance name of the spectrum measurement and Meas_RefR is the resistive load used.
    By default, the displayed spectrum extends from FMeasurement - 1/(2×TimeStep) Hz to FMeasurement + 1/(2×TimeStep) Hz. When FMeasurement < 1/(2×TimeStep), the default spectrum extends to negative frequencies. The spectral content at these negative frequencies is conjugated, mirrored, and added to the spectral content of the closest positive frequency. The negative frequency tones are then displayed on the positive frequency axis as would happen in an RF spectrum analyzer measurement instrument. This process may introduce an error in the displayed frequency for the mirrored tones. The absolute error introduced is less than (spectrum frequency step) / 2 (see Effect of Values for SpecMeasStart, SpecMeasStop, SpecMeasSubframes, and SpecMeasResBW for the definition of spectrum frequency step).
    The basis of the algorithm used by the spectrum measurement is the chirp-Z transform. The algorithm can use multiple subframes and average the results to achieve video averaging (see note 6).
  2. SpecMeasDisplayPages provides information regarding Data Display pages for this measurement. It cannot be changed by the user.
  3. SpecMeasStart sets the start time for collecting input data.
  4. SpecMeasStop sets the stop time for collecting input data when SpecMeasSubframes = 0 and SpecMeasResBW = 0.
  5. SpecMeasSubframes sets the number of segments over which data will be collected.
  6. SpecMeasResBW sets the resolution bandwidth of the spectrum.
    Depending on the values of SpecMeasStart, SpecMeasStop, SpecMeasSubframes, and SpecMeasResBW, the stop time may be adjusted or spectrum video averaging may occur (or both). The different cases are described in Effect of Values for SpecMeasStart, SpecMeasStop, SpecMeasSubframes, and SpecMeasResBW.
    Referring to Effect of Values for SpecMeasStart, SpecMeasStop, SpecMeasSubframes, and SpecMeasResBW, let
    Start = TimeStep × int((SpecMeasStart/TimeStep) + 0.5)
    Stop = TimeStep × int((SpecMeasStop/TimeStep) + 0.5)
    (This means Start and Stop are forced to be an integer number of time step intervals.)
    X = normalized equivalent noise bandwidth of the window
    Start and Stop times are used for RF_out and Meas_in signal spectrum analyses. The Meas_in signal is delayed in time from the RF_out signal by the value of the RF DUT time delay. Therefore, for RF DUT time delay >0, the RF_out and Meas_in signals are inherently different and spectrum display differences can be expected.
    TimeStep and SubframeTime are defined in the Test Bench Variables for Data Displays section.
    Equivalent noise bandwidth (ENBW) compares the window to an ideal, rectangular filter. It is the equivalent width of a rectangular filter that passes the same amount of white noise as the window. Normalized ENBW (NENBW) is ENBW multiplied by the duration of the signal being windowed. (Refer to note 7 regarding the various window options and Window Options and Normalized Equivalent Noise Bandwidth regarding NENBW for the various windows.)
    Effect of Values for SpecMeasStart, SpecMeasStop, SpecMeasSubframes, and SpecMeasResBW
    Case 1 SpecMeasSubframes = 0
    SpecMeasResBW = 0
    Resultant stop time = Stop
    Resultant resolution BW = X/(Stop - Start)
    Resultant spectrum frequency step = 1/(Stop-Start)
    Video averaging status = None
    Case 2 SpecMeasSubframes > 0
    SpecMeasResBW = 0
    Resultant stop time = Start + SpecMeasSubframes x SubframeTime
    For SpecMeasSubframes > 0 and SpecMeasResBW = 0
    Video averaging occurs over all segment time intervals
    Resultant resolution BW = X /SubframeTime
    Resultant spectrum frequency step = 1/SubframeTime
    Video averaging status = Yes, when SpecMeasSubframes > 1
    Case 3 SpecMeasSubframes = 0
    SpecMeasResBW > 0
    Resultant stop time = Start + N x SubframeTimeInterval
    where
    N = int((Stop -Start)/SubframeTimeInterval) + 1
    For SpecMeasSubframes = 0 and SpecMeasResBW > 0
    Define SubframeTimeInterval = TimeStep x int((X/SpecMeasResBW/TimeStep) + 0.5)
    This means SubframeTimeInterval is forced to a value that is an integer number of time step intervals.
    (Stop-Start) time is forced to be an integer number (N) of SubframeTimeIntervals
    N has a minimum value of 1
    Video averaging occurs over all SubframeTimeIntervals
    Resolution bandwidth achieved is ResBW = X / SubframeTimeInterval, which is very close to SpecMeasResBW but may not be exactly the same if X/SpecMeasResBW/TimeStep is not an exact integer.
    Resultant resolution BW = ResBW
    Resultant spectrum frequency step = ResBW
    Video averaging status = Yes when N > 1
    Case 4 SpecMeasSubframes > 0
    SpecMeasResBW > 0
    Resultant stop time = Start + M x SubframeTimeInterval
    where
    M = int((SpecMeasSubframes x SubframeTime)/SubframeTimeInterval) + 1
    For SpecMeasSubframes > 0 and SpecMeasResBW > 0
    Define SubframeTimeInterval = TimeStep x int(( X /SpecMeasResBW/TimeStep) + 0.5)
    This means SubframeTimeInterval is forced to a value that is an integer number of time step intervals.
    (Stop-Start) time is forced to be an integer number (M) of the SubframeTimeIntervals
    M has a minimum value of 1
    Video averaging occurs over all SubframeTimeIntervals
    Resolution bandwidth achieved is ResBW = X / SubframeTimeInterval, which is very close to SpecMeasResBW but may not be exactly the same if X/SpecMeasResBW/TimeStep is not an exact integer.
    Resultant resolution BW = ResBW
    Resultant spectrum frequency step = ResBW
    Video averaging status = Yes, when M > 1
  7. SpecMeasWindow specifies the window that will be applied to each segment before its spectrum is calculated. Different windows have different properties, affect the resolution bandwidth achieved, and affect the spectral shape. Windowing is often necessary in transform-based (chirp-Z, FFT) spectrum estimation in order to reduce spectral distortion due to discontinuous or non-harmonic signal over the measurement time interval. Without windowing, the estimated spectrum may suffer from spectral leakage that can cause misleading measurements or masking of weak signal spectral detail by spurious artifacts.
    The windowing of a signal in time has the effect of changing its power. The spectrum measurement compensates for this and the spectrum is normalized so that the power contained in it is the same as the power of the input signal.
    Window Type Definitions:
    • none

      where N is the window size
    • Hamming 0.54

      where N is the window size
    • Hanning 0.50

      where N is the window size
    • Gaussian 0.75

      where N is the window size
    • Kaiser 7.865

      where N is the window size,  α = N / 2, and I 0 (.) is the 0th order modified Bessel function of the first kind
    • 8510 6.0 (Kaiser 6.0)

      where N is the window size,  α = N / 2, and I 0 (.) is the 0th order modified Bessel function of the first kind
    • Blackman

      where N is the window size
    • Blackman-Harris

      where N is the window size.
      Window Options and Normalized Equivalent Noise Bandwidth
      Window and Default Constant NENBW
      none 1
      Hamming 0.54 1.363
      Hanning 0.50 1.5
      Gaussian 0.75 1.883
      Kaiser 7.865 1.653
      8510 6.0 1.467
      Blackman 1.727
      Blackman-Harris 2.021

EVM Measurement Parameters

The EVM measurement requires setting the MirrorMeasSpectrum parameter such that there is an even number of spectrum mirrorings from the combined test bench source and RF DUT. For example, if MirrorSourceSpectrum=NO and the RF DUT causes its output RF signal to have spectrum mirroring relative to its input signal, then set MirrorMeasSpectrum=YES.
The EVM measurement provides results for EVM, magnitude error, phase error for one code channel and for the composite signal. It also provides rho, frequency error, IQ offset, and gain imbalance.

  1. EVM_DisplayPages provides information regarding Data Display pages for this measurement. It cannot be changed by the user.
  2. Starting at the time instant specified by EVM_StartTime, a signal segment of 10msec is captured and the beginning of a subframe is detected (a 10msec signal segment is guaranteed to contain a whole subframe). After the subframe is detected, the I and Q envelopes of the input signal are extracted. The I and Q envelopes are then passed to a complex algorithm that performs synchronization, demodulation, and EVM analysis (this algorithm is the same as the one used in the Agilent 89600 VSA).
  3. If EVM_AverageType is set to Off, only one subframe is detected, demodulated, and analyzed.
    If EVM_AverageType is set to RMS (Video), after the first subframe is analyzed the signal segment corresponding to it is discarded and new signal samples are collected from the input to fill in the 10msec signal buffer. When the buffer is full again a new subframe is detected, demodulated, and analyzed. These steps are repeated until EVM_SubframesToAverage subframes are processed.
    If a subframe is mis-detected for any reason, results from its analysis are discarded. EVM results obtained from all the successfully detected, demodulated, and analyzed subframes are averaged to give the final averaged results. EVM results from each successfully analyzed subframe are also recorded (in the variables without the Avg_ prefix in their name).
  4. EVM_ActiveSlotThreshold sets the active slot detection threshold; that is the power level (in dB with respect to the power level of the slot with the largest measured power) below which a slot will be considered as inactive.

Signal to ESG Parameters

The EVM measurement collects data from the Meas_in signal and downloads it to an Agilent E4438C Vector Signal Generator. This measurement uses Connection Manager architecture to communicate with the instrument; parameters specify how data is interpreted.
Prerequisites for using the Signal to ESG option are:

Parameter Information

  1. EnableESG specifies if the signal is downloaded to the ESG instrument. If set to NO, no attempt will be made to communicate with the instrument.
  2. ESG_Instrument specifies a triplet that identifies the VSA resource of the instrument to be used in the simulation, the connection manager server hostname (defaults to localhost ), and the port at which the connection manager server listens for incoming requests (defaults to 4790). To ensure that this field is populated correctly, click Select Instrument , enter the server hostname and port, click OK to see the Remote Instrument Explorer dialog, select a VSA resource identifier, and click OK . For details about selecting instruments, see Instrument Discovery in the Wireless Test Bench Simulation documentation.
  3. ESG_Start and ESG_Stop (when ESG_Subframes=0) specify when to start and stop data collection. The number of samples collected, ESG_Stop - ESG_Start + 1, must be in the range 60 samples to 64 Msamples, where 1 Msample = 1,048,576 samples. The ESG requires an even number of samples; the last sample will be discarded if ESG_Stop - ESG_Start + 1 is odd.
  4. ESG_Subframes sets the number of subframes over which data will be collected. If ESG_Subframes is greater than zero, then ESG_Stop is forced to ESG_Start + ESG_Subframes x SubframeTime where SubframeTime is 5 msec.
  5. ESG_ClkRef specifies an internal or external reference for the ESG clock generator. If set to External, the ESG_ExtClkRefFreq parameter sets the frequency of this clock.
  6. ESG_IQFilter specifies the cutoff frequency for the reconstruction filter that lies between the DAC output and the Dual Arbitrary Waveform Generator output inside the ESG.
  7. ESG_SampleClkRate sets the sample clock rate for the DAC output.
  8. ESG_Filename sets the name of the waveform inside the ESG that will hold the downloaded data.
  9. The ESG driver expects data in the range {-1, 1}. The ESG_AutoScaling parameter specifies whether to scale inputs to fit this range. If set to YES, inputs are scaled to the range {-1, 1}; if set to NO, raw simulation data is downloaded to the ESG without any scaling, but data outside the range {-1, 1} is clipped to -1 or 1. If set to YES, scaling is also applied to data written to the local file (ESG_Filename setting).
  10. If ESG_ArbOn is set to YES, the ESG will start generating the signal immediately after simulation data is downloaded; if set to NO, waveform generation must be turned on at the ESG front panel.
  11. If ESG_RFPowOn is set to YES, the ESG will turn RF power on immediately after simulation data is downloaded. If ESG_RFPowOn is set to NO (default), RF power must be turned on at the ESG front panel.
  12. ESG_EventMarkerType specifies which ESG Event markers are enabled: Event1, Event2, Both, or Neither. Event markers are used for synchronizing other instruments to the ESG. When event markers are enabled, Event1 or Event2 (or both) is set beginning from the first sample of the downloaded Arb waveform over the range of points specified by the ESG_MarkerLength parameter. This is equivalent to setting the corresponding event from the front panel of the ESG.
  13. ESG_MarkerLength specifies the range of points over which the markers must be set starting from the first point of the waveform. Depending on the ESG_EventMarkerType setting, the trigger length of Event1 or Event2 (or both) is set to a multiple of the pulsewidth that, in turn, is determined by the sample clock rate of the DAC output.

Simulation Measurement Displays

After running the simulation, results are displayed in Data Display pages for each measurement activated.

Note
Measurement results from a wireless test bench have associated names that can be used in Data Display Expressions. For more information, refer to Measurement Results for Expressions for TD-SCDMA Wireless Test Benches.

RF Envelope Measurement

The RF Envelope measurement (not defined in 3GPP TS 25) shows the envelope of a TD-SCDMA uplink signal. Measurements for the RF signal at the input of the RF DUT and the Meas signal at the output of the RF DUT are implemented.
The real and imaginary parts of the RF and Meas signals are shown in RF Envelope Simulation Results. There are two active parts because ActiveTimeslot is set to TS1 and uplink pilot is transmitted. Only 2.6msec of data is stored to save disk space; the stop time can be changed by setting RF_EnvelopeMeasurement parameters.


RF Envelope Simulation Results

Constellation Measurement

The constellation measurement (not defined in 3GPP TS 25) shows the constellation of one code channel of the TD-SCDMA uplink signal. The constellation for the RF and Meas signals are shown in Signal Constellations. Through the constellation measurement, distortion caused by carrier phase shift, IQ imbalance, and phase noise can be observed. Comparing the RF and the Meas signals, the constellation of the Meas signal rotates a fixed angle due to the delay introduced by the DUT.

QPSK demodulation is implemented in the TD-SCDMA uplink. Symbol mapping is shown in Symbol Mapping.

Signal Constellations


Symbol Mapping
*Input <th
00 +j
01 +1
10 -1
11 -j

Power Measurement

The power measurement includes: power vs. time (defined in 3GPP TS 25.105 [3] and TS 25.142 [4] ); and, CCDF (not defined in 3GPP standards).

Power vs. time is the instant power of chips in the subframe (when PowerSubframeMeasured = 1) and average power of chips at the same position in all measured subframes (when PowerSubframeMeasured > 1). CCDF fully characterizes the power statistics of a signal and provides characterization of peak-to-average power ratio versus probability.
The on/off mask template for power vs. time is illustrated in Downlink Transmit On/Off Mask Template.

Results of power vs. time for the RF and Meas signals are shown in Power vs. Time in One Subframe; results of power vs. time with masks are shown in RF and Signal Power vs. Time with Masks.

To show the power vs. time on/off masks more clearly, zoomed-in RF and Meas signals are shown in RF Signal Power vs. Time with Masks Off and On and Meas Signal Power vs. Time with Masks Off and On.

If the curves meet the masks, Pass will show in the Data Display window; otherwise, Failure will show.

Downlink Transmit On/Off Mask Template

Power vs. Time in One Subframe

RF and Signal Power vs. Time with Masks

RF Signal Power vs. Time with Masks Off and On

Meas Signal Power vs. Time with Masks Off and On

The CCDF for the RF and the Meas signals are shown in Complementary Cumulative Distribution Function.

The peak-to-average power ratios of the RF and Meas signals are shown in Peak-to-Average Power Ratios.

Complementary Cumulative Distribution Function

Peak-to-Average Power Ratios

Spectrum Measurement

The spectrum measurement (not defined in 3GPP standards) shows the spectrum of the TD-SCDMA downlink signal. The spectrum analyzer output contains complex amplitude voltage values and the dBm(<meas_name>, <ref_r>) expressions can be used to convert to dBm values. Spectrums for the RF and the Meas signals are shown in TD-SCDMA Signal Spectrums.

TD-SCDMA Signal Spectrums

EVM Measurement

The EVM measurement (defined in 3GPP TS 25.102 and TS 34.122) demonstrates the uplink EVM measurement. EVM is a measure of the difference between the reference and the measured waveform; this difference is called the error vector. Both waveforms pass through a matched root raised-cosine filter with bandwidth corresponding to the considered chip rate and roll-off a=0.22. Both waveforms are further modified by selecting the frequency, absolute phase, absolute amplitude, and chip clock timing so as to minimize the error vector. The EVM result is defined as the square root of the ratio of the mean error vector power to the mean reference power expressed as a percent. The measurement interval is one timeslot. The EVM must not exceed 12.5%. The requirement is valid over the total power dynamic range as specified in subclause 6.4.3 of TS 25.102.

The results from this measurement are described in the following table.

EVM Measurement Results
Result Description
Avg_ChEVMrms_pct average channel EVM rms in %
ChEVMrms_pct channel EVM rms in % versus subframe
ChEVM_Pk_pct channel peak EVM in % versus subframe
ChEVM_Pk_symbol_idx channel peak EVM symbol index versus subframe
Avg_ChMagErr_rms_pct average channel magnitude error rms in %
ChMagErr_rms_pct channel magnitude error rms in % versus subframe
ChMagErr_Pk_pct channel peak magnitude error in % versus subframe
ChMagErr_Pk_symbol_idx channel peak magnitude error symbol index versus subframe
Avg_ChPhaseErr_deg average channel phase error in degrees
ChPhaseErr_deg channel phase error in degrees versus subframe
ChPhaseErr_Pk_deg channel peak phase error in degrees versus subframe
ChPhaseErr_Pk_symbol_idx channel peak phase error symbol index versus subframe
ChCodePhase_deg channel code phase (phase of the channel code with respect to the pilot) versus subframe
Avg_CompEVMrms_pct average composite EVM rms in %
CompEVMrms_pct composite EVM rms in % versus subframe
CompEVM_Pk_pct composite peak EVM in % versus subframe
CompEVM_Pk_chip_idx composite peak EVM chip index versus subframe
Avg_CompMagErr_rms_pct average composite magnitude error rms in %
CompMagErr_rms_pct composite magnitude error rms in % versus subframe
CompMagErr_Pk_pct composite peak magnitude error in % versus subframe
CompMagErr_Pk_chip_idx composite peak magnitude error chip index versus subframe
Avg_CompPhaseErr_deg average composite phase error in degrees
CompPhaseErr_deg composite phase error in degrees versus subframe
CompPhaseErr_Pk_deg composite peak phase error in degrees versus subframe
CompPhaseErr_Pk_chip_idx composite peak phase error chip index versus subframe
Avg_Rho average rho
Rho rho versus subframe
Avg_FreqError_Hz average frequency error in Hz
FreqError_Hz frequency error in Hz versus subframe
Avg_IQ_Offset_dB average IQ offset in dB
IQ_Offset_dB IQ offset in dB versus subframe
Avg_QuadErr_deg average quadrature error in degrees
QuadErr_deg quadrature error in degrees versus subframe
Avg_GainImb_dB average IQ gain imbalance in dB
IQ_GainImb_dB IQ gain imbalance in dB versus subframe

If EVM_AverageType is set to RMS (Video), EVM will be measured in EVM_SubframesToAverage subframes. If EVM_AverageType is set to Off, EVM will be measured in the first subframe detected. Results named with the Avg_ prefix are results averaged over the number of subframes specified by the user in EVM_SubframesToAverage (when EVM_AverageType is set to RMS (Video)). Results that are not named Avg_ are results versus subframe. RF signal results are shown in RF Signal Average and Peak EVM; Meas signal results are shown in Meas Signal Average and Peak EVM.

RF Signal Average and Peak EVM

Meas Signal Average and Peak EVM

RF signal results for averaged EVM, magnitude error, and phase error of one code channel and composite channel are shown in RF Signal EVM, Magnitude Error, and Phase Error Results; Meas signal results are shown in Meas Signal EVM, Magnitude Error, and Phase Error Results. According to the 3GPP standard, the EVM must not exceed 12.5%; EVM results for the RF and the Meas signals meet specification requirements.

RF Signal EVM, Magnitude Error, and Phase Error Results

Meas Signal EVM, Magnitude Error, and Phase Error Results

Test Bench Variables for Data Displays

Reference variables used to set up this test bench are listed in Test Bench Equations Derived from Test Bench Parameters and Exported to Data Display.

Test Bench Equations Derived from Test Bench Parameters and Exported to Data Display
Data Display Parameter Equation with Test Bench Parameters
RF_FSource FSource
RF_Power_dBm 10 × log10(SourcePower)+30
RF_R SourceR
TimeStep 1/(ChipRate × SamplesPerChip)
ActiveSlot ActiveTimeslot
SubframeTime 5 msec
FilterLength RRC_FilterLength
Meas_FMeasurement FMeasurement
Meas_R MeasR

Baseline Performance

Expected ADS Performance

Expected ADS performance is the combined performance of the baseline test bench and the RF DUT Circuit Envelope simulation with the same signal and number of time points. For example, if the RF DUT performance with Circuit Envelope simulation alone takes 2 hours and consumes 200 MB of memory (excluding the memory consumed by the core ADS product), then add these numbers to the Baseline Performance numbers to determine the expected ADS performance. This is valid only if the full memory consumed is from RAM. If RAM is less, larger simulation times may result due to increased disk access time for swap memory usage.

References for Downlink Transmitter Test

  1. 3GPP TS 25.221, "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Physical channels and mapping of transport channels onto physical channels (TDD) (Release 4)," version 4.5.0, June, 2002.
    http://www.3gpp.org/ftp/Specs/2002-06/Rel-4/25_series/25221-450.zip]
  2. 3GPP TS 25.223, "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Spreading and modulation (TDD) (Release 4)," version 4.4.0, March, 2002.
    http://www.3gpp.org/ftp/Specs/2002-06/Rel-4/25_series/25223-440.zip]
  3. 3GPP TS 25.105, "3rd Generation Partnership Project; Technical Specification Group Radio Access Networks; BS Radio transmission and Reception (TDD) (Release 4)," version 4.5.0, June, 2002.
    http://www.3gpp.org/ftp/Specs/2002-06/Rel-4/25_series/25105-450.zip]
  4. 3GPP TS 25.142 V4.5.0 "3rd Generation Partnership Project; Technical Specification Group Radio Access Networks; Base station conformance testing (TDD) (Release 4)," version 4.5.0, June, 2002.
    http://www.3gpp.org/ftp/Specs/2002-06/Rel-4/25_series/25142-450.zip]
    Setting up a Wireless Test Bench Analysis in the Wireless Test Bench Simulation documentation explains how to use test bench windows and dialogs to perform analysis tasks.
    Setting Circuit Envelope Analysis Parameters in the Wireless Test Bench Simulation documentation explains how to set up circuit envelope analysis parameters such as convergence criteria, solver selection, and initial guess.
    Setting Automatic Verification Modeling Parameters in the Wireless Test Bench Simulation documentation explains how to improve simulation speed.
 

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