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WCDMA3G Base Station Receiver Design Examples

Introduction

The WCDMA3G_BS_Rx_prj project shows base station receiver measurement characteristics, including reference sensitivity levels, dynamic range, adjacent channel selectivity, blocking and intermodulation characteristics, and wanted signal calibration.

Designs for these measurements are described in the following sections; they include:

  • Reference sensitivity levels: BS_Rx_RefLevel.dsn
  • Dynamic range: BS_Rx_DynamicRange.dsn
  • Adjacent channel selectivity: BS_Rx_ACS.dsn
  • Blocking characteristics: BS_Rx_Blocking.dsn
  • Intermodulation characteristics: BS_Rx_Intermod.dsn

Designs under this project consist of:

  • Uplink RF band signal source

3GPPFDD_RF_Uplink is used to provide a RF 3GPPFDD uplink signal source. The parameter of this subnetwork is shown in the following table.

3GPPFDD_RF_Uplink Parameters

Name

Description

Value Range

SpecVersion

version of specifications: Version_03_00, Version_12_00, Version_03_02

ROut

output resistance

(0,+∞)

FCarrier

frequency of carrier, in MHz

(0,+∞)

Power

output power, in dBm

(-∞,+∞)

PhasePolarity

if set to Invert, Q channel signal is inverted: Normal, Invert

GainImbalance

gain imbalance, I to Q channel, in dB

(-∞,+∞)

PhaseImbalance

phase imbalance, I to Q channel, in degrees

(-∞,+∞)

I_OriginOffset

I origin offset in percent with respect to output rms voltage

(-∞,+∞)

Q_OriginOffset

Q origin offset in percent with respect to output rms voltage

(-∞,+∞)

IQ_Rotation

IQ rotation in degrees

(-∞,+∞)

NDensity

additive noise density in dBm per Hz

(-∞,+∞)

SamplesPerChip

samples per chip

(0,+∞)

ExcessBW

excess bandwidth of raised cosine filters

[0,1]

FilterLength

length of raised cosine filters in number of symbols

(0,+∞)

RefCh

reference measurement channel: UL_REF_12_2, UL_REF_64, UL_REF_144, UL_REF_384_10, UL_REF_384_20, UL_REF_768, UL_REF_2048

DPCCH_SltFmt

DPCCH slot format

[0, 5]

ScrambleType

scramble type: Long, Short

integer

ScrambleCode

index of scramble code

[0, 16777215]

GainIndex

gain index

[0, 15]

The schematic for this subnetwork is shown in the following figure.

3GPPFDD_RF_Uplink Schematic

12.2 kbps UL reference measurement channel is used in all RX measurements. One 12.2 kbps DTCH (dedicated transport channel) and one 2.4 kbps DCCH (dedicated control channel) are multiplexed into one 60 kbps DPDCH (dedicated physical data channel). The 60 kbps DPDCH and 15 kbps DPCCH (dedicated physical control channel) are I/Q multiplexed into one data stream using different spreading factors (64 for DPDCH and 256 for DPCCH), then scrambled with the specified scrambling code. The amplitude ratio of DPCCH/DPDCH is 0.7333 according to the Annex A of TS25.104.

The data source of baseband output from 3GPPFDD_UL_Source is directly modulated to 1950 MHz by WCDMA3G_RF_Mod. The IF to RF up-converter is removed in order to save simulation time.

  • Channel loss and interfering signal combination

The transmitted RF signal is then attenuated by RF channel (RF_Gain model) and combined with interfering signals (modulated or continuous waveform) at given frequency offsets using RF_IQ. The modulated interfering signals are input from an outside model.

  • Base station RF receiver

3GPPFDD_RF_Uplink_Receiver is used to provide a receiver of RF 3GPP uplink signals. The parameter of this subnetwork is shown in the following table.

Name

Description

Value Range

SpecVersion

version of specifications: Version_03_00, Version_12_00, Version_03_02

RLoad

input resistance

(0,+∞)

FCarrier

frequency of carrier, in MHz

(0,+∞)

Phase

demodulator reference phase in degrees

VRef

reference voltage for output power calibration

(0,+∞)

SamplesPerChip

samples per chip

(0,+∞)

ExcessBW

excess bandwidth of raised cosine filters

[0,1]

FilterLength

length of raised cosine filters in number of symbols

(0,+∞)

RefCh

reference measurement channel: UL_REF_12_2, UL_REF_64, UL_REF_144, UL_REF_384_10, UL_REF_384_20, UL_REF_768, UL_REF_2048

DPCCH_SltFmt

DPCCH slot format

[0, 5]

ScrambleType

scramble type: Long, Short

integer

ScrambleCode

index of scramble code

[0, 16777215]

MaxDelaySample

maximum delay boundary in term of sample

[0, 2559]

ChannelType

select the channel type to be processed: CH_GAUSSIAN, CH_FADING

ChannelInfo

fading channel information source: Known, Estimated

ChannelInfoOffset

offset between spread code and channel information in terms of sample

PathSearch

path search frequency: EverySlot, Once

SearchMethod

path search method: Coherent, NonCoherent, Combined

SearchSlotsNum

number of slots for path search

[1, 6]

PathNum

number of Rake fingers

[1, 6]

PathDelaySample

delay for each finger in term of samples

[0, MaxDelaySample]

The schematic for this subnetwork is shown in the following figure.

At the receiver side, the received signal is demodulated to be the baseband signal by WCDMA3G_RF_Demod.

3GPPFDD_UL_Rx_RefCH is used to demodulate and decode the receiving baseband signals and BER values of DTCH and DCCH; BER values of DPDCH are calculated with the decode output of DTCH and DCCH.

  • BER Calculation

3GPPFDD_RF_Uplink_BER is used to measure DPCH, DCCH and DTCH BER of 3GPP uplink channel. The parameter of this subnetwork is shown in the following table.

Name

Description

Value Range

FrameNum

frame number

(0,+∞)

RefCh

reference measurement channel: UL_REF_12_2, UL_REF_64, UL_REF_144, UL_REF_384_10, UL_REF_384_20, UL_REF_768, UL_REF_2048

The schematic for this subnetwork is shown in the following figure.

Common variables used in these designs are listed in the following table.

Common VAR Parameters

Parameter Name

Description

Default Value

SpecVersion

Specification version

2

RefCh

Reference measurement channel

0

SamplePerChip

Samples per chip

8

FrameNum

Number of frames to be measured

4

TStep

Time step

1/(3840000 × SamplesPerChip)

FilterLength

Filter length in terms of samples

16

FCarrier

RF carrier frequency

1950 (MHz)

SourceR

Source resistance

50 (ohm)

SourceDelay

Source delay

(2 × int(FilterLength × SamplesPerChip/2) + 1) × TStep

Reference Sensitivity Level Measurements

BS_Rx_RefLevel.dsn Design

Features
  • Base station receiver reference sensitivity level measurements
  • Uplink reference measurement channels
  • Integrated RF models
  • BER of transport channels
  • Decoded output data

Description

This design measures base station receiver reference sensitivity level according to section 7.2 in TS25.104. The schematic is shown in the following figure.

BS_Rx_RefLevel.dsn Schematic

The reference sensitivity is the minimum receiver input power measured at the antenna connector at which the BER does not exceed the value (0.001) specified in section 7.2.1.

Gain factors of RF models in this design are set to satisfy the following conditions per section 7.2.1 in TS 25.104 version 3.2.0:

  • = −121dBm/3.84 MHz
  • BER performance must not exceed 0.001.
Base Station Reference Sensitivity Levels

Measurement Channel

BS Reference Sensitivity Level

BER

12.2 kbps

-121 dBm

BER ≤ 0.001

Simulation Results

Simulation results are shown in the following figure.

BER Results for Base Station Reference Sensitivity Level Measurement

Benchmark
  • Simulation time is approximately 5 minutes on a P4/2.2G 512M PC powered by MS Windows 2000 and ADS 2003C for 4 frames.

Dynamic Range Measurements

BS_Rx_DynamicRange.dsn

Features
  • Base station receiver dynamic range measurement
  • Uplink reference measurement channels
  • Integrated RF models
  • BER of transport channels
  • Decoded output data

Description

This design measures the base station receiver dynamic range according to section 7.3 in TS25.104. The schematic is shown in the following figure.

BS_Rx_DynamicRange.dsn Schematic

Receiver dynamic range is the receiver's ability to handle a rise of interference in the reception frequency channel. The receiver must fulfill a specified BER for a specified sensitivity degradation of the requisite signal in the presence of an interfering AWGN signal in the same reception frequency channel.

The BER must not exceed 0.001 with parameters listed in the following table.

Base Station Dynamic Range

Parameter

Level

Unit

Data rate

12.2

kbps

Requisite signal

-91

dBm

Interfering AWGN signal

-73

dBm/3.84 MHz

Gain factors of RF models in this design are set to satisfy the following conditions specified in section 7.3.1 of TS 25.104:

  • = −91dBm/3.84 MHz
  • AWGN Signal Power = −73dBm/3.84 MHz
  • BER performance of DTCH and DCCH must not exceed 0.001.

Simulation Results

Simulation results are shown in the following figure.

Dynamic Range Measurement Simulation Results

Benchmark
  • Simulation time is approximately 5 minutes on a P4/2.2G 512M PC powered by MS Windows 2000 and ADS 2003C for 4 frames.

Adjacent Channel Selectivity Measurements

BS_Rx_ACS.dsn

Features
  • Base station receiver adjacent channel selectivity measurements
  • Uplink reference measurement channels
  • Integrated RF models
  • BER of transport channels
  • Decoded output data

Description

This design measures base station receiver adjacent channel sensitivity (ACS) according to section 7.4 in TS25.104. The schematic is shown in the following figure.

BS_Rx_ACS.dsn Schematic

ACS is a measure of the receiver's ability to receive the requisite signal at its assigned channel frequency in the presence of an adjacent channel signal at a given frequency offset from the center frequency of the assigned channel. ACS is the ratio of the receiver filter attenuation on the assigned channel frequency to the receive filter attenuation on the adjacent channel(s). The BER must not exceed 0.001.

Base Station Adjacent Channel Selectivity

Parameter

Level

Unit

Data rate

12.2

kbps

Requisite signal

-115

dBm

Interfering signal

-52

dBm/3.84 MHz

Fuw (Modulated)

5

MHz

The gain factors of RF models in this design are set to satisfy the following conditions per section 7.4.1 in TS 25.104 version 3.2.0:

  • = −115dBm/3.84 MHz
  • Interfering Signal Power = −52dBm/3.84 MHz
  • Interfering Signal Frequency Offset = 5 MHz
  • BER performance of DTCH and DCCH must not exceed 0.001.

Simulation Results

Simulation results are shown in the following figure.

Adjacent Channel Selectivity Measurement Simulation Results

Benchmark
  • Simulation time is approximately 9 minutes on a P4/2.2G 512M PC powered by MS Windows 2000 and ADS 2003C for 4 frames.

Blocking Characteristics Measurements

BS_Rx_Blocking.dsn Design

Features
  • Base station receiver adjacent channel selectivity measurements
  • Uplink reference measurement channels
  • Integrated RF models
  • BER of transport channels
  • Decoded output data

Description

This design measures base station receiver blocking characteristics according to section 7.5 in TS25.104. The schematic is shown in the following figure.

BS_Rx_Blocking.dsn Schematic

Blocking characteristics is a measure of the receiver's ability to receive the requisite signal at its assigned channel frequency in the presence of an interfering signal on frequencies other than those of the adjacent channels. The blocking performance must apply at all frequencies as specified in the following table, using a 1 MHz step size. The BER must not exceed 0.001.

Base Station Blocking Characteristics
Center Frequency of Interfering Signal Interfering Signal Level Requisite Signal Level Minimum Offset of Interfering Signal Type of Interfering Signal
1920-1980 MHz -40 dBm -115 dBm 10 MHz WCDMA signal with one code
1900-1920 MHz 1980-2000 MHz -40 dBm -115 dBm 10 MHz WCDMA signal with one code
1-1900 MHz 2000-12750 MHz -15 dBm -115 dBm   CW carrier
only this signal is implemented

The gain factors of RF models in this design are set to satisfy the following conditions per section 7.5.1 in TS 25.104:

  • = −115dBm/3.84 MHz
  • Interfering Signal Power = −40dBm/3.84 MHz
  • Interfering Signal Frequency Offset = 10 MHz
  • BER performance of DTCH and DCCH must not exceed 0.001.

Simulation Results

Simulation results are shown in the following figure.

Blocking Measurements Simulation Results

Benchmark
  • Simulation time is approximately 9 minutes on a P4/2.2G 512M PC powered by MS Windows 2000 and ADS 2003C for 4 frames.

Intermodulation Characteristics Measurements

BS_Rx_Intermod.dsn

Features
  • Base station receiver adjacent channel selectivity measurements
  • Uplink reference measurement channels
  • Integrated RF models
  • BER of transport channels
  • Decoded output data

Description

This design measures base station receiver intermodulation characteristics according to section 7.6 in TS25.104. The schematic is shown in the following figure.

BS_Rx_Intermod.dsn Schematic

Third- and higher-order mixing of the two interfering RF signals can produce an interfering signal in the band of the requisite channel. Intermodulation response rejection is a measure of the receiver's ability to receive the requisite signal on its assigned channel frequency in the presence of two or more interfering signals that have a specific frequency relationship to the requisite signal. The BER must not exceed 0.001.

Base Station Intermodulation Performance Requirement
Requisite Signal Level Interfering Signal Level Offset Type of Interfering Signal
-115 dBm -48 dBm 10 MHz CW Signal
20 MHz WCDMA signal with one code

Gain factors of RF models in this design are set to satisfy the following conditions per section 7.6.1 in TS 25.104:

  • = −115dBm/3.84 MHz
  • Interfering CW signal power = −48 dBm
  • Interfering CW signal frequency offset = 10 MHz
  • Interfering modulated signal power = −48 dBm
  • Interfering modulated signal frequency offset = 20 MHz
  • BER performance of DTCH and DCCH must not exceed 0.001.

Simulation Results

Simulation results are shown in the following figure.

Intermodulation Simulation Results

Benchmark
  • Simulation time is approximately 20 minutes on a P4/2.2G 512M PC powered by MS Windows 2000 and ADS 2003C for 4 frames.

References

  1. 3GPP Technical Specification TS 25.104 V3.5.0, "UTRA(BS) FDD: Radio transmission and Reception," December 2000.
  2. 3GPP Technical Specification TS 25.141 V3.4.1, "Base station conformance test," December 2000.
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