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90 Keysight WLAN Measurement Guide

Concepts
WLAN Standards

802.11a

802.11a operates in the 5 GHz band and uses orthogonal frequency division

multiplexing (OFDM) as its transmission scheme.

See “Orthogonal Frequency

Division Multiplexing (OFDM) Concepts” on page 104.

The 802.11a offers 6, 12 and 24 Mbps and optionally 9, 18, 36, 48 and 54 Mbps

bit-rates. The OFDM physical layer uses 52 sub-carriers with 0.3125 MHz

spacing, of which 48 are used to carry data and 4 are used as pilots. The

occupied bandwidth is 16.6 MHz. Forward error correction coding

(convolutional coding) is used with a coding rate of 1/2, 2/3, or 3/4.
The modulation of the individual carriers in the OFDM depends on the data

rates. For 6 and 9 Mbps BPSK is used, 12 and 18 Mbps uses QPSK, 24 and 36

Mbps uses 16 QAM, and 48 and 54 Mbps operation uses 64 QAM.

Table 3-2 on

page 90

provides a summary of the different modulation formats used in OFDM

systems and their associated rate-dependent parameters.

Number of

carriers per

channel

48 data &

4 pilot

1 (DSSS)

48 data &

4 pilot

- 52 data &

4 pilot

(20 MHz)
- 108 data &

6 pilot

(40 MHz)

- 52 data &

4 pilot

(20 MHz)
- 108 data &

6 pilot

(40 MHz)
- 234 data &

8 pilot

(80 MHz)
- 468 data &

16 pilot

(160 MHz)

MIMO

4 x 4

8 x 8,

Multi-user MIMO

Table 3-1

IEEE 802.11 Standards Family

Wireless LAN Standards

802.11a

802.11b

802.11g

802.11n

802.11ac

Table 3-2

802.11a Rate-dependent parameters

Data rate

(Mbps)

Modulation

Coding

rate (R)

Coded bits per

subcarrier

(NBPSC)

Coded bits

per OFDM

symbol

(NCBPS)

Data bits

per OFDM

symbol

(NDBPS)

BPSK

1/2

BPSK

3/4

QPSK

1/2

Содержание x series

Страница 1: ...Application Measurement Guide Keysight X Series Signal Analyzers This manual provides documentation for the following models PXA Signal Analyzer N9030A MXA Signal Analyzer N9020A EXA Signal Analyzer N9010A CXA Signal Analyzer N9000A ...

Страница 2: ...t customers under its standard commercial license which is embodied in its End User License Agreement EULA a copy of which can be found at http www keysight com find sweula The license set forth in the EULA represents the exclusive authority by which the U S government may use modify distribute or disclose the Software The EULA and the license set forth therein does not require or permit among oth...

Страница 3: ...t com find exa http www keysight com find cxa To receive the latest updates by email subscribe to Keysight Email Updates at the following URL http www keysight com find MyKeysight Information on preventing instrument damage can be found at www keysight com find PreventingInstrumentRepair Is your product software up to date Periodically Keysight releases software updates to fix known defects and in...

Страница 4: ...4 ...

Страница 5: ...tton Measurement Channel Power 23 Example of Using SCPI Commands 23 Making Occupied Bandwidth Measurements 24 Configuring the Measurement System 24 Measurement Example Signal Settings 25 Measurement Procedure 25 Viewing Occupied BW Measurement Results 25 Example of One Button Measurement Occupied BW 26 Example of Using SCPI Commands 27 Making Power Stat CCDF Measurements 28 Configuring the Measure...

Страница 6: ...atness Measurements 51 Configuring the Measurement System 51 Measurement Example Signal Settings 52 Measurement Procedure 52 Viewing Spectral Flatness Measurement Results 53 Example of One Button Measurement Spectral Flatness 53 Example of Using SCPI Commands 54 Making Modulation Analysis Measurements 55 Configuring the Measurement System 55 Measurement Example Signal Settings 56 Measurement Proce...

Страница 7: ...89 Overview 89 802 11a 90 802 11b 93 802 11g 94 802 11n 95 802 11ac 96 Digital Modulation Format Standards 97 Introduction 97 Modulation Formats and WLAN standards 97 Spread Spectrum Concepts 102 Direct Sequence Spread Spectrum DSSS 102 Complementary Code Keying CCK 102 Packet Binary Convolutional Coding PBCC 103 Orthogonal Frequency Division Multiplexing OFDM Concepts 104 MIMO Multi Input Multi O...

Страница 8: ...8 Keysight N6141A Measurement Guide Contents List Sequence Measurement Concepts 116 Monitor Spectrum Measurement Concepts 117 IQ Waveform Measurement Concepts 118 ...

Страница 9: ... W9077A WLAN Measurement Application Measurement Guide 1 About WLAN Measurement Application This chapter provides overall information on the Keysight N9077A W9077A WLAN Measurement Application and describes the measurements made by the analyzer ...

Страница 10: ...bove Turbo mode 40 MHz 802 11j 10 MHz 20 MHz and 802 11p 5 MHz 10 MHz 20 MHz are also supported based on the preset of the related standards The Option N9077A W9077A WLAN measurement application provides the following one button measurements Channel Power Measurement Occupied Bandwidth OBW Measurement Power Stat CCDF Measurement Spectrum Emission Mask Measurement Spurious Emissions Measurement Pow...

Страница 11: ...7 4 7 4 18 3 9 3 17 4 7 4 20 3 20 1 22 3 18 1 24 3 16 1 Spectrum Emission Mask Transmission Spurious 18 3 9 4 17 4 6 8 18 3 9 4 Spurious Emissions Center Frequency Tolerance 18 3 9 5 17 4 7 5 18 3 9 5 19 4 8 3 20 3 20 4 22 3 18 3 24 3 16 3 Freq Errorb Symbol Chip Clock Frequency Tolerance 18 3 9 6 17 4 7 6 18 3 9 6 19 4 8 4 20 3 20 6 22 3 18 3 24 3 16 3 Symbol Chip Clock Errorb Center Frequency Le...

Страница 12: ...9077A 3FP TP plus N9077A 4FP TP 802 11a b g j p 802 11n 802 11ac 802 11a b g j p 802 11n 802 11ac N9077A 6FP TP 802 11ah 802 11ah N9077A 5FP TP N A List Sequence measurement only requires Option B40 To fully support 802 11n both 20 MHz and 40 MHz functionality it is required to install one of the following hardware 1 40 MHz Analysis Bandwidth Option B40 for PXA MXA and EXA or 2 160 MHz Analysis Ba...

Страница 13: ... MHz 160 MHz 16 MHz N9030A PXA B25 B25 B40 B85 B1X B25 N9020A MXA Default Default B40 B85 or B1A 125 MHz B1X Default N9010A EXA Default Default B40 N A N A Default N9000A CXA B25 B25 N A N A N A B25 If you have installed N9077A 3FP TP license and don t install 40 MHz or above bandwidth hardware when you make a 802 11n 40 MHz measurement you will get an error message If you have installed N9077A 4F...

Страница 14: ...14 Keysight WLAN Measurement Guide About WLAN Measurement Application N9077A W9077A WLAN Measurement Application Licensing ...

Страница 15: ...WLAN Measurement Application Measurement Guide 2 Making WLAN Measurements This chapter describes procedures to set up and perform measurements for analysis of WLAN signals Details of the steps necessary for accurate signal analysis are provided as well ...

Страница 16: ...this mode Channel Power Occupied Bandwidth OBW Power Stat CCDF Spectrum Emission Mask Spurious Emissions Power vs Time Spectral Flatness Modulation Analysis List Sequence MXA EXA with Option B40 only Monitor Spectrum I Q Waveform Before you can begin making measurements make sure you have installed the required license 1 Press Mode and check to make sure that WLAN is available 2 Press Meas and che...

Страница 17: ...wer vs Time Measurements on page 47 Making Spectral Flatness Measurements on page 51 Making Modulation Analysis Measurements on page 55 Making WLAN List Sequence WLS Measurements on page 67 Making Monitor Spectrum Measurements on page 78 Making I Q Waveform Measurements on page 82 Troubleshooting WLAN Measurements on page 85 For more information on how to make Channel Power measurement Occupied Ba...

Страница 18: ... factory default state press Mode Preset This initializes the analyzer by returning the mode setup and all of the measurement setups in the mode to the factory default parameters To preset the parameters that are specific to an active selected measurement press Meas Setup Meas Preset This returns all the measurement setup parameters to the factory defaults but only for the currently selected measu...

Страница 19: ... to all measurements in the mode 2 Select and Set Up the Measurement a Press Meas b Select the specific measurement to be performed c Press Meas Setup The measurement begins as soon as any required trigger conditions are met The resulting data is shown on the display or is available for export Use Meas Setup to make any required adjustment to the selected measurement settings The settings only app...

Страница 20: ...or Making Measurements Step Primary Key Setup Keys Related Keys Select and set up a mode Mode Mode Setup FREQ Channel System Select and set up a measurement Meas Meas Setup Sweep Control Restart Single Cont Select and set up a view of the results View Display SPAN X Scale AMPTD Y Scale Peak Search Quick Save Save Recall File Print ...

Страница 21: ...vice under test DUT which generates WLAN signals to the signal analyzer RF input port as shown in WLAN Measurement Setup on page 21 Figure 2 2 WLAN Measurement Setup See the Input Key menu for details on selecting input ports and the AMPTD Y Scale menu for details on setting internal attenuation to prevent overloading the analyzer Before connecting a signal to the analyzer make sure the analyzer c...

Страница 22: ...o Making Channel Power Measurements on page 21 Step Action Notes 1 Select WLAN Mode a Press MODE WLAN 2 Preset the analyzer a Press Mode Preset button for the factory preset b To recall a user defined Preset Press User Preset User Preset to preset the current mode 3 Select the desired radio standard a Press MODE Setup Radio Std 802 11n 802 11n 40 MHz 4 If necessary select the frequency settings a ...

Страница 23: ...to the input Step 1 Press Mode Preset Step 2 Press Meas Channel Power Step 3 View the measurement default view See Figure 2 3 Figure 2 3 Channel Power Default View If you have a problem and get an error message see Instrument Messages Example of Using SCPI Commands Select WLAN mode INST WLAN Select the Channel Power measurement CONF CHP Get the measurement result Channel Power dBm READ CHP CHP ...

Страница 24: ...he device under test DUT which generates WLAN signals to the signal analyzer RF input port as shown in WLAN Measurement Setup on page 21 Figure 2 4 WLAN Measurement Setup See the Input Key menu for details on selecting input ports and the AMPTD Y Scale menu for details on setting internal attenuation to prevent overloading the analyzer Before connecting a signal to the analyzer make sure the analy...

Страница 25: ...a Press Mode Preset button for the factory preset b To recall a user defined Preset Press User Preset User Preset to preset the current mode 3 Select the desired radio standard a Press MODE Setup Radio Std 802 11n 802 11n 40 MHz 4 If necessary select the frequency settings a Press FREQ Channel 2412 MHz 5 Select the measurement a Press MEAS Occupied BW 6 Examine the keys that are available to chang...

Страница 26: ...er s Reference Click to Go Back to Making Occupied Bandwidth Measurements on page 24 Example of One Button Measurement Occupied BW This example assumes the signal is correctly applied to the input Step 1 Press Mode Preset Step 2 Press Meas Occupied BW Step 3 View the measurement default view See Figure 2 5 Figure 2 5 Occupied BW Default View If you have a problem and get an error message see Instr...

Страница 27: ...ements Making Occupied Bandwidth Measurements Example of Using SCPI Commands Select WLAN mode INST WLAN Select the Occupied BW measurement CONF OBW Get the measurement result bandwidth Hz occupied by a given percentage of the total mean power READ OBW OBW ...

Страница 28: ...device under test DUT which generates WLAN signals to the signal analyzer RF input port as shown in WLAN Measurement Setup on page 21 Figure 2 6 WLAN Measurement Setup See the Input Key menu for details on selecting input ports and the AMPTD Y Scale menu for details on setting internal attenuation to prevent overloading the analyzer Before connecting a signal to the analyzer make sure the analyzer...

Страница 29: ...equency settings a Press FREQ Channel 2412 MHz 5 Select the measurement a Press MEAS Power Stat CCDF 6 Optimize the attenuation level and attenuation settings suitable for the measurement a Press AMPTD Attenuation Adjust Atten for Min Clip 7 Store your current measurement trace for future reference a Press Trace Detector Store Ref Trace 8 Display the stored trace a Press Trace Detector Ref Trace O...

Страница 30: ...to capture the desired part of the burst signal a Press Meas Setup Meas Interval then input your settings according to your signal Meas Interval equals to the time gate effect on the signal 12 Select the Power Stat CCDF measurement again or restart the measurement a Press Meas Power Stat CCDF or press Restart Step Action Notes ...

Страница 31: ... trace is displayed in magenta For more information on what these data are see the N9077A W9077A WLAN Measurement Application User s and Programmer s Reference Click to Go Back to Making Power Stat CCDF Measurements on page 28 Example of One Button Measurement Power Stat CCDF This example assumes the signal is correctly applied to the input Step 1 Press Mode Preset Step 2 Press Meas Power Stat CCD...

Страница 32: ... by adjusting the trigger parameters within the CCDF measurement OFDM bursts are variable in length Therefore the first task is to identify the total length of the burst This can be done using the Power vs Time measurement The total length of the burst can be found using markers Place a marker on the left edge of the burst to indicate the start of that burst Then place a delta marker at the end of...

Страница 33: ...he marker at the rising edge of the burst c Press Delta and use the knob to place the marker at the falling edge of the burst d Read the delta marker value for example 180 µs 7 Turn off the Trig Delay a Press Trigger External 1 Trig Delay and switch to Off 8 Set a marker to measure the hardware delay a Press Marker More All Markers Off b Press Marker Select Marker Marker 1 Use the knob to place th...

Страница 34: ...urement Guide Making WLAN Measurements Making Power Stat CCDF Measurements Figure 2 8 Time domain view of the 802 11a burst to measure total length Figure 2 9 Time domain view of the 802 11a burst to measure hardware delay ...

Страница 35: ...Keysight WLAN Measurement Guide 35 Making WLAN Measurements Making Power Stat CCDF Measurements Figure 2 10 CCDF measurement of the 802 11a burst ...

Страница 36: ...of the device under test DUT which generates WLAN signals to the signal analyzer RF input port as shown in WLAN Measurement Setup on page 21 Figure 2 11 WLAN Measurement Setup See the Input Key menu for details on selecting input ports and the AMPTD Y Scale menu for details on setting internal attenuation to prevent overloading the analyzer Before connecting a signal to the analyzer make sure the ...

Страница 37: ...a user defined Preset Press User Preset User Preset to preset the current mode 3 Select the desired radio standard a Press MODE Setup Radio Std 802 11n 802 11n 40 MHz 4 If necessary select the frequency settings a Press FREQ Channel 2412 MHz 5 Select the measurement a Press MEAS Spectrum Emission Mask 6 Examine the keys that are available to change measurement parameters from their default conditi...

Страница 38: ...A WLAN Measurement Application User s and Programmer s Reference Click to Go Back to Making Spectrum Emission Mask Measurements on page 36 Before making SEM measurements for a 802 11p signal you need to load the desired 802 11p limit mask file for your test Step Action Notes 1 Select the radio standard a Press MODE Setup Radio Std 802 11a b g 802 11a g OFDM 2 Examine the available mask files for 8...

Страница 39: ...s Meas Spectrum Emission Mask Step 3 View the measurement default view See Figure 2 12 Figure 2 12 Spectrum Emission Mask Default View If you have a problem and get an error message see Instrument Messages Example of Using SCPI Commands Select WLAN mode INST WLAN Select the Spectrum Emission Mask measurement CONF SEM Get the 14 comma separated pass fail test results 0 passed 1 failed determined by...

Страница 40: ...cale Attenuation Mech Atten and enter 0 dB When the signal level is low for example 30 dBm set the attenuation to 0 dB 5 Turn on the Gate View a Press Sweep Control Gate and switch Gate View to On 6 Change the Res BW for Ref Channel from 100 kHz to 8 MHz a Press Meas Setup Ref Channel Res BW and enter 8 MHz The maximum Res BW setting is 8 MHz to set the accurate Gate Delay and Gate Length in time ...

Страница 41: ...f Channel Res BW and enter 100 kHz 10 Change the Res BW for each Offset from 8 MHz to 100 kHz a Press Meas Setup Offset Limits Select Offset Offset A More Res BW and enter 100 kHz b Set the same Res BW for Offset B C D E F respectively By default Offset E and F are turned off 11 Turn on Average function to smooth the display if necessary a Press Meas Setup Avg Hold Num and enter the average number...

Страница 42: ...42 Keysight WLAN Measurement Guide Making WLAN Measurements Making Spectrum Emission Mask Measurements Figure 2 14 Using RBW 100 kHz to get accurate SEM measurement results ...

Страница 43: ...he device under test DUT which generates WLAN signals to the signal analyzer RF input port as shown in WLAN Measurement Setup on page 21 Figure 2 15 WLAN Measurement Setup See the Input Key menu for details on selecting input ports and the AMPTD Y Scale menu for details on setting internal attenuation to prevent overloading the analyzer Before connecting a signal to the analyzer make sure the anal...

Страница 44: ...all a user defined Preset Press User Preset User Preset to preset the current mode 3 Select the desired radio standard a Press MODE Setup Radio Std 802 11n 802 11n 40 MHz 4 If necessary select the frequency settings a Press FREQ Channel 2412 MHz 5 Select the measurement a Press MEAS Spurious Emissions 6 Examine the keys that are available to change measurement parameters from their default conditi...

Страница 45: ...esult of the selected range in Range under Meas Setup Range Table is shown in yellow For more information on what these data are see the N9077A W9077A WLAN Measurement Application User s and Programmer s Reference Click to Go Back to Making Spurious Emissions Measurements on page 43 Example of One Button Measurement Spurious Emissions This example assumes the signal is correctly applied to the inp...

Страница 46: ...aking WLAN Measurements Making Spurious Emissions Measurements Example of Using SCPI Commands Select WLAN mode INST WLAN Select the Spurious Emissions measurement CONF SPUR Get the measurement result the number of spurs found READ SPUR 22 ...

Страница 47: ...vice under test DUT which generates WLAN signals to the signal analyzer RF input port as shown in WLAN Measurement Setup on page 21 Figure 2 17 WLAN Measurement Setup See the Input Key menu for details on selecting input ports and the AMPTD Y Scale menu for details on setting internal attenuation to prevent overloading the analyzer Before connecting a signal to the analyzer make sure the analyzer ...

Страница 48: ...he current mode 3 Select the desired radio standard a Press MODE Setup Radio Std 802 11n 802 11n 40 MHz 4 If necessary select the frequency settings a Press FREQ Channel 2412 MHz 5 Select the measurement a Press MEAS Power vs Time 6 Examine the keys that are available to change measurement parameters from their default conditions a Press Meas Setup then select the parameters you want to change and...

Страница 49: ...Rise Fall View includes three windows Rising RF Envelope window Falling RF Envelope window and Numeric Results window For more information on what these data are see the N9077A W9077A WLAN Measurement Application User s and Programmer s Reference Click to Go Back to Making Power vs Time Measurements on page 47 Example of One Button Measurement Power vs Time This example assumes the signal is corre...

Страница 50: ... 19 Power vs Time Rise Fall View If you have a problem and get an error message see Instrument Messages Example of Using SCPI Commands Select WLAN mode INST WLAN Select the Power Stat CCDF measurement CONF PVT Get the measurement result waveform of full bust the length is actual burst length READ PVT 4 ...

Страница 51: ...e device under test DUT which generates WLAN signals to the signal analyzer RF input port as shown in WLAN Measurement Setup on page 21 Figure 2 20 WLAN Measurement Setup See the Input Key menu for details on selecting input ports and the AMPTD Y Scale menu for details on setting internal attenuation to prevent overloading the analyzer Before connecting a signal to the analyzer make sure the analy...

Страница 52: ...a Press MODE Setup Radio Std 802 11n 802 11n 40 MHz 4 If necessary select the frequency settings a Press FREQ Channel 2412 MHz 5 Select the measurement a Press MEAS Spectral Flatness 6 Examine the keys that are available to change measurement parameters from their default conditions a Press Meas Setup then select the parameters you want to change and input your settings For example to avoid the FF...

Страница 53: ... between the limit lines the measurement will pass The text window shows Radio Format Info Max Point to Upper Limit and Min Point to Lower Limit for Section 1 and Section 2 For more information on what these data are see the N9077A W9077A WLAN Measurement Application User s and Programmer s Reference Click to Go Back to Making Spectral Flatness Measurements on page 51 Example of One Button Measure...

Страница 54: ...de Making WLAN Measurements Making Spectral Flatness Measurements Example of Using SCPI Commands Select WLAN mode INST WLAN Select the Spectral Flatness measurement CONF FLAT Get the Spectral Flatness results of each section READ FLAT ...

Страница 55: ...the device under test DUT which generates WLAN signals to the signal analyzer RF input port as shown in WLAN Measurement Setup on page 21 Figure 2 22 WLAN Measurement Setup See the Input Key menu for details on selecting input ports and the AMPTD Y Scale menu for details on setting internal attenuation to prevent overloading the analyzer Before connecting a signal to the analyzer make sure the ana...

Страница 56: ...ency settings a Press FREQ Channel 2412 MHz 5 Select the measurement a Press MEAS Modulation Analysis 6 Examine the keys that are available to change measurement parameters from their default conditions a Press Meas Setup then select the parameters you want to change and input your settings Pressing Optimize EVM can improve your EVM results of OFDM signals 7 Specify the demodulation results for a ...

Страница 57: ...z IQ Measured Polar Graph OFDM EVM Demod Bits Numeric Results To make Modulation Analysis measurements for a 802 11p signal you need to follow the steps below Step Action Notes 1 Select the radio standard a Press Mode Setup Radio Std 802 11a b g and 802 11a g 2 Adjust the subcarrier spacing for your test a Press Subcarrier Spacing and enter the desired value For a 10 MHz 802 11p signal you can ent...

Страница 58: ...on User s and Programmer s Reference Click to Go Back to Making Modulation Analysis Measurements on page 55 Example of One Button Measurement Modulation Analysis This example assumes the signal is correctly applied to the input Step 1 Press Mode Preset Step 2 Press Meas Modulation Analysis Step 3 View the measurement views See Figure 2 23 The default measurement results should look like Figure 2 2...

Страница 59: ...h Default View For the 802 11n example signal the Burst Info HT Sig Info view should look like Figure 2 24 and shows the OFDM Data Burst Info window and the HT Sig Info window The Burst Info window shows the information about the analyzed burst The HT Sig shows the decode info on HT Sig and L Sig Figure 2 24 Modulation Analysis Burst Info HT Sig Info view ...

Страница 60: ... Guide Making WLAN Measurements Making Modulation Analysis Measurements For the 802 11n example signal the Demod Bits view should look like Figure 2 25 and shows the demodulated bits Figure 2 25 Modulation Analysis Demod Bits view ...

Страница 61: ...asurements Making Modulation Analysis Measurements For the 802 11n example signal the Numeric Results view should look like Figure 2 26 and shows a summary for the measurement result and information Figure 2 26 Modulation Analysis Numeric Results view ...

Страница 62: ...lysis Measurements For the 802 11n example signal the OFDM EVM view should look like Figure 2 27 and shows a combination of RMS EVM vs Symbol window RMS EVM vs Subcarrier window I Q Measured Polar Graph window and Numeric Results window Figure 2 27 Modulation Analysis OFDM EVM view ...

Страница 63: ...ows a Preamble Freq Error vs Time window It shows the total frequency error in Hz for the preamble part of the burst Figure 2 28 Modulation Analysis Preamble Freq Error vs Time view If you have a problem and get an error message see Instrument Messages Example of Using SCPI Commands Select WLAN mode INST WLAN Select the Channel Power measurement CONF EVM Get the measurement result Demod Bits READ ...

Страница 64: ...ps below to do it manually Optimize EVM key is not available when 802 11b g is selected or 802 11ac 80MHz 80MHz is selected or Option B25 is only installed or N9000A CXA is used Steps Action Notes For signals with power level around 10 dBm or higher 1 Set the attenuator automatically for minimal clipping a Press AMPTD Attenuation Adjust Atten for Min Clip The firmware limits the mechanical attenua...

Страница 65: ...F Gain a Press Meas Setup Advanced More IF Gain and select High Gain b Adjust the Mech Atten setting if needed This adds 10 dB of gain to the signal For signals with power level around 40 dBm 1 Switch the IF Gain to Low Gain a Press Meas Setup Advanced More IF Gain and select Low Gain 2 Turn on the preamplifier a Press AMPTD More Internal Preamp Full Range b Adjust the Mech Atten setting if needed...

Страница 66: ...ple using PXA with Option B1X to capture the signal below WLAN signal radio standard 802 11ac 80 MHz MCS Index 8 Data Length 1024 bytes The Max Search Time Length is 20 ms and each frame duration of the signal above is 88 μs then Max Number of Burst 20 ms 88 μs 227 If any parameter of the WLAN signal is changed like bandwidth MCS or data length the frame duration will change and the max number of ...

Страница 67: ...h generates WLAN signals to the signal analyzer RF input port as shown in WLAN Measurement Setup on page 21 Figure 2 29 WLAN Measurement Setup See the Input Key menu for details on selecting input ports and the AMPTD Y Scale menu for details on setting internal attenuation to prevent overloading the analyzer This measurement is supported by MXA and EXA with Option B40 only Before connecting a sign...

Страница 68: ...om Device Under Test DUT should be repeating 3 times therefore the valid bursts can be identified and analyzed In a sequence the maximum number of bursts is 45 The primary UI for this measurement is SCPI commands There is no menu displayed under Meas Setup All the settings under Meas Setup are SCPI only For the SCPI commands with different parameters and the detailed usage of each SCPI command ple...

Страница 69: ...t trigger parameters These are used for the entire sequence Table 2 4 SCPI Commands for WLS Measurement 3 SCPI Commands Notes WLS CAPT BURS NUMB 12 Set the measured burst number The maximum number of analyzed bursts is 45 WLS ACQ1 SET AG 1 98GHz 5dBm 15dBm 20us 700us 1 436ms EXT1 40dB m 0us WLS ACQuire2 SETup AG 1 983GHz 5dBm 15dBm 20us 700us 1 436ms RFB 40d Bm 0us WLS ACQuire12 SETup AG 2 013GHz ...

Страница 70: ...LIM STAT ON CALC WLS TXP LIM STAN1 TPOW 16 0 CALC WLS TXP LIM STAN1 PSD 4 0 Set the test limits for each standard and each measurement if needed This command is optional WLS EVM FILT REF TYPE GAUS WLS EVM FILT ALPH 0 22 WLS EVM FILT MEAS TYPE NONE WLS EVM CRAT 11 0MHz WLS EVM CADJ 0 5 WLS EVM EQU LENG 21 WLS EVM EQU OFF WLS EVM DESC ALL Set the parameters for 802 11b Optional if you don t measure ...

Страница 71: ... key board Figure 2 30 WLS Result Metrics View Pressing View Display Parameter List you can see the available SCPI commands listed alphabetically for this measurement You can verify and change values with DOWN UP key from either the front panel or key board Table 2 6 SCPI Commands for WLS Measurement 5 SCPI Commands Notes READ WLS1 After this command is sent to the analyzer all results are returne...

Страница 72: ... List Sequence WLS Measurements Figure 2 31 WLS Parameter Metrics View For more information on what these data are see the N9077A W9077A WLAN Measurement Application User s and Programmer s Reference Click to Go Back to Making WLAN List Sequence WLS Measurements on page 67 ...

Страница 73: ...Pe POSitive TRIGger WLSequence EXTernal1 SLOPe POSitive TRIGger WLSequence EXTernal1 LEVel 1 2V TRIGger WLSequence EXTernal2 SLOPe POSitive TRIGger WLSequence EXTernal2 LEVel 1 2V WLSequence POWer ATTenuation 6dB WLSequence ASRLevels PPMargin 5dB WLSequence CAPT BURS NUMB 12 CALC WLS TXP BURS STAR 1 CALC WLS TXP BURS STOP 12 CALC WLS EVM BURS STAR 1 CALC WLS EVM BURS STOP 12 CALC WLS TOSP BURS STA...

Страница 74: ...s WLS ACQuire12 SETup AG 2 013GHz 5dBm 15dBm 20us 700us 1 436ms RFB 40dBm 0us WLSequence EVM STANdard1 TIME INTerval 60 WLSequence EVM STANdard1 SUBCarrier SPACing 312 5kHz WLSequence EVM STANdard1 GINTerval LENGth 0 25 WLSequence EVM STANdard1 SYMBol ADJust 3 125 WLSequence EVM STANdard1 STSequence SHORt CALCulate WLSequence EVM STANdard1 PILot TRACk AMPLitude OFF CALCulate WLSequence EVM STANdar...

Страница 75: ...ard3 PILot TRACk AMPLitude OFF CALCulate WLSequence EVM STANdard3 PILot TRACk PHASe ON CALCulate WLSequence EVM STANdard3 PILot TRACk TIMing OFF CALCulate WLSequence EVM STANdard3 EQUalizer TMODe SEQ CALCulate WLSequence EVM STANdard3 IQNorm ON WLSequence EVM STANdard3 COMPensate OFF CALCulate WLSequence EVM STANdard3 SPECtrum NORMal WLSequence EVM STANdard4 TIME INTerval 60 WLSequence EVM STANdar...

Страница 76: ...nce EVM STANdard6 SUBCarrier SPACing 312 5kHz WLSequence EVM STANdard6 GINTerval LENGth 0 25 WLSequence EVM STANdard6 SYMBol ADJust 3 125 WLSequence EVM STANdard6 STSequence SHORt CALCulate WLSequence EVM STANdard6 PILot TRACk AMPLitude OFF CALCulate WLSequence EVM STANdard6 PILot TRACk PHASe ON CALCulate WLSequence EVM STANdard6 PILot TRACk TIMing OFF CALCulate WLSequence EVM STANdard6 EQUalizer ...

Страница 77: ...rd7 IQNorm ON WLSequence EVM STANdard7 COMPensate OFF CALCulate WLSequence EVM STANdard7 SPECtrum NORMal WLSequence EVM FILTer REFerence TYPE GAUSsian WLSequence EVM FILTer ALPHa 0 22 WLSequence EVM FILTer MEASurement TYPE NONE WLSequence EVM CRATe 11 0MHz WLSequence EVM CADJust 0 5 WLSequence EVM EQUalizer LENGth 21 WLSequence EVM EQUalizer OFF WLSequence EVM DESCramble ALL OPC READ WLS1 ...

Страница 78: ... device under test DUT which generates WLAN signals to the signal analyzer RF input port as shown in WLAN Measurement Setup on page 21 Figure 2 32 WLAN Measurement Setup See the Input Key menu for details on selecting input ports and the AMPTD Y Scale menu for details on setting internal attenuation to prevent overloading the analyzer Before connecting a signal to the analyzer make sure the analyz...

Страница 79: ...rrent mode 3 Select the desired radio standard Press MODE Setup Radio Std 802 11n 802 11n 40 MHz 4 If necessary select the frequency settings a Press FREQ Channel 2412 MHz 5 Select the measurement a Press MEAS Monitor Spectrum The default display shows the Current yellow trace data To make viewing the display easier you can view either the Current trace or Average separately 6 Examine the keys tha...

Страница 80: ...Measurement Application User s and Programmer s Reference Click to Go Back to Making Monitor Spectrum Measurements on page 78 Example of One Button Measurement Monitor Spectrum This example assumes the signal is correctly applied to the input Step 1 Press Mode Preset Step 2 Press Meas Monitor Spectrum Step 3 View the measurement default view See Figure 2 33 Figure 2 33 Monitor Spectrum Default Vie...

Страница 81: ...AN Measurements Making Monitor Spectrum Measurements Example of Using SCPI Commands Select WLAN mode INST WLAN Select the Monitor Spectrum measurement CONF MON Get the measurement result trace 1 data with comma separated floating numbers READ MON ...

Страница 82: ...ice under test DUT which generates WLAN signals to the signal analyzer RF input port as shown in WLAN Measurement Setup on page 21 Figure 2 34 WLAN Measurement Setup See the Input Key menu for details on selecting input ports and the AMPTD Y Scale menu for details on setting internal attenuation to prevent overloading the analyzer Before connecting a signal to the analyzer make sure the analyzer c...

Страница 83: ...ference Click to Go Back to Making I Q Waveform Measurements on page 82 Step Action Notes 1 Select WLAN Mode a Press MODE WLAN 2 Preset the analyzer a Press Mode Preset button for the factory preset b To recall a user defined Preset Press User Preset User Preset to preset the current mode 3 Select the desired radio standard a Press MODE Setup Radio Std 802 11n 802 11n 40 MHz 4 If necessary select ...

Страница 84: ... Mode Preset Step 2 Press Meas IQ Waveform Step 3 View the measurement default view See Figure 2 35 Figure 2 35 I Q Waveform Default View If you have a problem and get an error message see Instrument Messages Example of Using SCPI Commands Select WLAN mode INST WLAN Select the I Q Waveform measurement CONF WAV Get the measurement result unprocessed I Q trace data as a series of trace point values ...

Страница 85: ...meter setting is not available for current standard 224 Illegal Parameter The parameter setting is not available for current settings 215 Sync error Preamble not found The preamble code is not detected 217 Demod error Invalid packet type Packet type detected is not recognized 217 Demod error Acq time too short Not an entire Payload is captured that is the acquisition time is too short 159 Settings...

Страница 86: ...86 Keysight WLAN Measurement Guide Making WLAN Measurements Troubleshooting WLAN Measurements ...

Страница 87: ...cepts This chapter describes the concepts and theory of WLAN signals and explains how the various measurements are performed by the instrument Suggestions for optimizing and troubleshooting your setup are provided along with a list of related Keysight documents that are referenced for further information ...

Страница 88: ...le of IEEE 802 11 standards Digital Modulation Format Standards on page 97 contains a general description of the modulation format families including basic formats and WLAN specific formats Spread Spectrum Concepts on page 102 explains the DSSS concepts and theories Orthogonal Frequency Division Multiplexing OFDM Concepts on page 104 explains the OFDM concepts and theories WLAN Measurement Concept...

Страница 89: ...ned in the IEEE 802 11 standards family as summarized in the table below Table 3 1 IEEE 802 11 Standards Family Wireless LAN Standards 802 11a 802 11b 802 11g 802 11n 802 11ac Frequency band 5 GHz 2 4 GHz 2 4 GHz 2 4 GHz 5 GHz 5 GHz Channel bandwidth 20 MHz 22 MHz 20 MHz 20 MHz 40 MHz 20 MHz 40 MHz 80 MHz 160 MHz 80 80 MHz Maximum raw data rate 54 Mbps 11 Mbps 54 Mbps 600 Mbps 6 93 Gbps Transmit T...

Страница 90: ...e data rates For 6 and 9 Mbps BPSK is used 12 and 18 Mbps uses QPSK 24 and 36 Mbps uses 16 QAM and 48 and 54 Mbps operation uses 64 QAM Table 3 2 on page 90 provides a summary of the different modulation formats used in OFDM systems and their associated rate dependent parameters Number of carriers per channel 48 data 4 pilot 1 DSSS 48 data 4 pilot 52 data 4 pilot 20 MHz 108 data 6 pilot 40 MHz 52 ...

Страница 91: ...nt information such as frequency and burst length because these formats are less prone to bit errors Figure 3 1 802 11a Spectrum View shows an 802 11 a signal burst The spectrum is not very uniform This is caused in part by the preambles but mostly by the data being transmitted Figure 3 1 802 11a Spectrum View 18 QPSK 3 4 2 96 72 24 16 QAM 1 2 4 192 96 36 16 QAM 3 4 4 192 144 48 64 QAM 2 3 6 288 1...

Страница 92: ...nnels with 5 MHz spacing from 5 GHz to 6 GHz as well as the flexibility to define channelization sets for all current and future regulatory domains The set of valid operating channel numbers by regulatory domain is defined in Table 3 4 Table 3 3 Transmit power level for the United States Frequency band GHz Maximum output power with up to 6 dBi antenna gain mW 5 15 5 25 40 2 5 mW MHz 5 25 5 35 200 ...

Страница 93: ...chieve 5 5 and 11 Mbps rates the spreading length is first reduced from 11 to 8 This increases the symbol rate from 1 Msps to 1 375 Msps So for 5 5 Mbps bit rates one needs to transmit 5 5 1 375 or 4 bits symbol and for 11 Mbps 8 bits symbol The approach taken for 802 11b which keeps the QPSK spread spectrum signal and still provides the required number of bits symbol uses all but two of the bits ...

Страница 94: ...des of increased throughput PBCC utilizing 8PSK and an optional CCK OFDM mode which combines the 802 11b preamble with an OFDM packet In addition to data rates the 802 11b supports the 802 11g also allows various data rates using various modulation schemes such as 11 Mbps using PBCC 11 22 Mbps using PBCC 22 or CCK PBCC 33 Mbps operation using PBCC 33 respectively For 54 Mbps operation CCK OFDM mod...

Страница 95: ... for Japan and 802 11p for vehicular applications Both use the half clock rate as defined in the standard Because 802 11n defines 77 possible permutations of the factors that determine data rate a new concept has been defined for 802 11n called MCS Modulation and Coding Scheme MCS assigns a simple integer to every permutation of modulation coding rate guard interval channel width and number of spa...

Страница 96: ... spatial streams up to 8 to increase data rates over existing 802 11n products The 802 11ac Technical Specification is currently in draft form the Standard finalization is anticipated in late 2012 with final 802 11 working Group approval in late 2013 The table below Part 2 list MCS values index 0 9 currently supported by N9077A W9077A WLAN measurement application MCS index Type Coding rate Spatial...

Страница 97: ...QAM are described in standard RF texts Often the modulation format changes during the transmission This is because the early part of the burst contains important information about the burst including analog characteristics such as frequency and digital information such as burst length Simpler modulation formats are less prone to bit errors and thus are more suitable to use early in a burst Modulat...

Страница 98: ...ulation QAM Concepts on page 99 802 11g DSSS DSSS 1 Mbps DSSS 2 Mbps CCK 5 5 Mbps CCK 11 Mbps PBCC 5 5 Mbps PBCC 11 Mbps PBCC 22Mbps PBCC 33Mbps OFDM BPSK QPSK 16 QAM 64 QAM 802 11n OFDM BPSK QPSK 16 QAM 64 QAM 802 11ac OFDM BPSK QPSK 16 QAM 64 QAM 256 QAM 802 11ah OFDM BPSK QPSK 16 QAM 64 QAM 256 QAM Table 3 6 Families of Digital Modulation Formats WLAN Standard Carrier Type Modulation Format ...

Страница 99: ... to 135 45 or 135 degrees These points are chosen as they can be easily implemented using an I Q modulator Only two I values and two Q values are needed and this gives two bits per symbol There are four states because 22 4 It is therefore a more bandwidth efficient type of modulation than BPSK potentially twice as efficient Figure 3 4 Phase Shift Keying PSK Quadrature Amplitude Modulation QAM Conc...

Страница 100: ...ght bits A 256 QAM signal that can send eight bits per symbol is very spectrally efficient However for a given maximum power the symbols are closer together than lower valued QAM s and are thus more subject to errors due to noise and distortion Such a signal may have to be transmitted with extra power to effectively spread the symbols out more and this reduces power efficiency as compared to simpl...

Страница 101: ...tion the symbol clock can be recovered but it is noisy and the symbol locations themselves are noisy In some cases a symbol will fall far enough away from its intended position that it will cross over to an adjacent position The I and Q level detectors used in the demodulator would misinterpret such a symbol as being in the wrong location causing bit errors QPSK is not as efficient but the states ...

Страница 102: ... of the spreading code or that it is a D BPSK data signal spread by a BPSK spreading sequence producing a BPSK constellation Figure 3 6 DSSS signal spreading for 2 Mbps data rate Complementary Code Keying CCK CCK Complementary Code Keying Changing both the spreading factor and or the modulation format varies the bit rate CCK is used to increase IEEE 802 11b s peak data rate from 2 to 11 Mbps while...

Страница 103: ...y a 0 5 dB increase is required for this data rate increase In PBCC the real data rate increase comes from moving from QPSK to 8PSK as the modulation technique while the reduction in required signal to noise ratio comes from using PBCC over CCK It makes use of Forward Error Correction to improve the link performance when noise is the limitation Scrambled data is fed into a convolutional encoder Th...

Страница 104: ...s in all 48 of which are used to carry data and 4 which are used as pilots Orthogonal Frequency Division Multiplexing OFDM has been formally accepted as the method to achieve high data rates better than 20 Mbps in the WLAN systems OFDM provides multiple frequency channels at regular spacing each modulated by M ary QAM An OFDM signal consists of the sum of a number of sub carriers that are modulate...

Страница 105: ...na and one receive antenna are used This is the form of communications that has been the default since radio began and is the baseline against which all the multiple antenna techniques are compared MISO Slightly more complex than SISO is multiple input single output MISO mode which uses two or more transmitters and one receiver SIMO The third mode shown in Figure 3 10 is single input multiple outp...

Страница 106: ...ly identifiable so that each receiver can determine what combination of transmissions has been received This identification is usually done with pilot signals which use orthogonal patterns for each antenna The theoretical gains from MIMO are a function of the number of transmit and receive antennas the radio propagation conditions the ability of the transmitter to adapt to the changing conditions ...

Страница 107: ...ine filter with user settable α and filter bandwidth Ability to turn the Root Raised Cosine filter on or off The Channel Power measurement uses Integration Bandwidth IBW method to calculate signal channel power When the Channel Power measurement is activated the appropriate integration bandwidth is set according to the selected radio standard The power in the integration bandwidth is measured and ...

Страница 108: ...1 Channel Power Measurement Result 802 11n Occupied Bandwidth Measurement Concepts Purpose Occupied bandwidth measurements express the bandwidth occupied by a given percentage of the total mean power of a signal This percentage is typically 99 Measurement Method The Occupied Bandwidth measurement is performed in two calculation stages First the instrument uses Integration Bandwidth IBW method to c...

Страница 109: ...encies number of active codes and correlation between symbols on different codes with spread spectrum systems will all affect measurement results These factors are all related to modulation and signal parameters External factors such as signal compression and expansion by nonlinear components group delay distortion from filtering and power control within the observation interval also affect the me...

Страница 110: ...ove the level defines the probability for that particular power level For capturing a lower probability down to 0 0001 this measurement is made in the single mode To make the power statistics CCDF measurement the instrument uses digital signal processing DSP to sample the input signal in the channel bandwidth The Gaussian distribution line as the band limited Gaussian noise CCDF reference line the...

Страница 111: ...centered at the carrier channel frequency bandwidth The specifications require the reference to be the PSD of the signal The reference power therefore can be obtained in 100kHz resolution bandwidth as a reference PSD related to 100kHz Each offset peak PSD displayed is either a relative PSD to the peak PSD in the signal or an absolute PSD This measurement requires the user to specify measurement ba...

Страница 112: ...er than the Peak Excursion value will be added to a list of spurs displayed in the lower results window A total of 200 spurs can be recorded for one measurement with a limit of 10 spurs per frequency range To improve repeatability you can increase the number of averages From the spurs in the list those with peak amplitude greater than the Absolute Limit for that range will be logged as a measureme...

Страница 113: ...el The burst center point in time is determined and then the required masks are aligned in time with the center point To make a precise slope detection its threshold level and detection interval techniques are incorporated to extract only steep enough slopes out from the noise like signals In this measurement trigger must be provided by the user Depending on trigger the signal which is a little bi...

Страница 114: ...nergy of the constellations in each of the subcarriers with indices 16 1 and 1 16 defined as Section 1 shall deviate no more than 2 dB from their average energy The average energy of the constellations in each of the subcarriers with indices 28 17 and 17 28 defined as Section 2 shall deviate no more than 2 4 dB from the average energy of subcarriers with indices 16 1 and 1 16 In a 40 MHz transmiss...

Страница 115: ...covered by identifying exactly the type of degradation present in the signal and even help reveal any impairments that occur at the base band filters I Q modulators IF and RF sections of the transmitter The root mean square RMS of the error vectors is computed and expressed as a percentage of the square root of the mean power of the ideal signal1 For a regular QAM or a Phase Shift Keyed PSK signal...

Страница 116: ...s the burst and compute measurement results in some cases computing averaged results finally displays the measurement results in various views Figure 3 16 I Q Polar Constellation and Related Parameters List Sequence Measurement Concepts Purpose The List Sequence measurement is used to provide fast results on MXA and EXA This measurement makes multiple acquisitions to acquire multiple WLAN bursts w...

Страница 117: ...t allows the user to specify the data time over which the measurement is made Transition time is used to define the hardware switching time between this burst and the next burst The user should ensure the exact alignment of the analyzer and the DUT in terms of these parameters The user also need to set up the measurement parameters for making acquisitions and making List Sequence measurements It i...

Страница 118: ... time domain This measurement is how the instrument performs the zero span functionality found in traditional spectrum analyzers Basic mode waveform measurement data may be displayed using either a Signal Envelope window or an I Q window which shows the I and Q signal waveforms in parameters of voltage versus time The advantage of having an I Q view available while making a waveform measurement is...

Страница 119: ...This information is subject to change without notice Keysight Technologies 2012 2017 Edition 1 January 2017 N90077 90004 www keysight com ...

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