3GPPFDD EVM

3GPPFDD_EVM

Description: 3GPP FDD EVM measurement
Library: 3GPPFDD, Measurement
Class: SDF3GPPFDD_EVM
Derived From: 3GPPFDD_MeasBase

Parameters

† [0:5] for uplink DPCCH;

[0:16] for downlink DPCH;

[0:17] for downlink SCCPCH;

[0:5] for uplink PCPCH (Ver 03_00);

[0:2] for uplink PCPCH (Ver 12_00);

[0:1] for uplink PCPCH (Ver 03_02);

Uplink DPCCH spread factor is 256;

Spread Factor is 512 when down link DPCH SlotFormat is 0 and 1;

Spread Factor is 256 when down link DPCH SlotFormat is 2, 3, 4, 5, 6, and 7;

Spread Factor is 128 when down link DPCH SlotFormat is 8, 9, 10, and 11;

Spread Factor is 64 when down link DPCH SlotFormat is 12;

Spread Factor is 32 when down link DPCH SlotFormat is 13;

Spread Factor is 16 when down link DPCH SlotFormat is 14;

Spread Factor is 8 when down link DPCH SlotFormat is 15;

Spread Factor is 4 when down link DPCH SlotFormat is 16;

Pin Inputs

Notes/Equations

1. This subnetwork model measures EVM that is used to evaluate modulation accuracy. The schematic for this subnetwork is shown in the following figure.
   
   

   3GPPFDD_EVM Schematic

2. To measure EVM, reference and test signals must be fully time-aligned. And, the EVM value measurement interval must be one slot. Therefore, both reference and test signals must be synchronized to the slot boundary.
3. To ensure high synchronization accuracy, the signals are upsampled to 128 samples per chip by a 6-order Lagrange interpolator. The upsampled signals are then correlated with the specified spreading codes. The largest correlation value is used to determine the synchronization point. For more information of the synchronization process and the use of SlotFormat, SpreadCode, Correlator, SCH, and CPICH parameters, refer to 3GPPFDD_Synch.
4. The MaxDelaySample parameter is the size of correlation window. This parameter must be set large enough to cover the slot boundary to be determined. However, a larger window size will result in longer simulation time.
5. The synchronized reference and test signals calculate the EVM value. The system model is:
   Z(k) is the complex vector produced by observing the real transmitter at the optimal phase of symbol k. S ( k ) is the reference (ideal) signal of symbol k sampled at the same phase as that of Z ( k ). The transmitter model is

   Z(k) = {C₀+ C₁[S(k)+ E(k)]}W ^k

   W = exp(dr + jda) accounts for both a frequency offset giving da radians per symbol phase rotation and an amplitude change of dr nepers per symbol
   C₀ is a constant origin offset representing quadrature modulator imbalance
   C₁ is a complex constant representing the arbitrary phase and output power of the transmitter
   E ( k ) is the residual vector error on sample S(k). The error vector E(k) is measured and calculated for each instance k.

   

   The sum square vector error for each component is calculated over one burst. The relative RMS vector error is defined as

   

6. This subnetwork model supports EVM measurements over multiple slots. StartSlot specifies the offset where the measurement starts; SlotNum is the number of slots to be measured. The EVM value can be expressed as Ratio or Percentage, as controlled by EVMValue.
   EVM over different slots is expressed as individual values. For example, if StartSlot = 12, and SlotNum = 4, the measurement will start from the 12th slot of the first frame, and the EVM will be measured over the last three slots of the first frame plus the first slot of the next frame.
   This EVM algorithm automatically corrects the IQ origin offset. If the IQ origin offset is to be counted as a modulation error, the EVM value measured by this model could be smaller.
7. RefSlotBoundary and TestSlotBoundary are used to set the slot boundary for reference and test signals, respectively. If the value is set to 0, the slot boundary is determined by the synchronization model; otherwise, the non-zero value is taken as the slot boundary. Please note this boundary is for the interpolated slot that has a higher sample rate.
   If the test signal is severely impaired, the slot boundary may not be correctly determined by the internal synchronization model. In these cases, the source where the impairment is introduced must first be removed manually. The slot boundary reported in the simulation panel measured under ideal conditions can then be written back to the parameter set to specify the correct slot boundary.
8. Use of this model is demonstrated in base station and user equipment transmitter examples: File > Example Project > WCDMA3G > WCDMA3G_BS_Tx_prj > BS_Tx_EVM.dsn and WCDMA3G_UE_Tx_prj > UE_Tx_EVM.dsn. Simulation results are provided in Data Display windows for these designs.
9. Previous releases included a SpreadFactor parameter; the SlotFormat parameter now includes the spread factor.

References

1. 3GPP Technical Specification TS 25.211 V3.10.0, Physical channels and mapping of transport channels onto physical channels (FDD), March 2003, Release 1999.

   http://www.3gpp.org/ftp/Specs/2002-03/R1999/25_series/25211-3a0.zip

2. 3GPP Technical Specification TS 34.121 V3.8.0, Terminal Conformance Specification, Radio Transmission and Reception (FDD), March 2003, Release 1999.

   http://www.3gpp.org/ftp/Specs/2002-03/R1999/34_series/34121-380.zip