bleCSWaveform

Generate Bluetooth LE CS PHY waveform

Since R2024b

Syntax

csPHYWaveform = bleCSWaveform(cfgChannelSounding)

[csPHYWaveform,accessAddress] = bleCSWaveform(cfgChannelSounding)

Description

csPHYWaveform = bleCSWaveform(cfgChannelSounding) generates a Bluetooth^® low energy (LE) channel sounding (CS) physical layer (PHY) waveform from the configuration specified by cfgChannelSounding.

example

[csPHYWaveform,accessAddress] = bleCSWaveform(cfgChannelSounding) additionally generates a 32-bit access address for the Bluetooth LE device from the CS deterministic random bit generator (DRBG) function.

Examples

collapse all

Generate and Visualize Bluetooth LE Channel Sounding PHY Waveform

Open Live Script

Generate and visualize a Bluetooth LE CS PHY waveform by using this CS procedure.

Channel Sounding Tutorial Workflow.png

Using this example, you can:

Generate a CS PHY waveform at the Initiator.
Add propagation delay and additive white Gaussian noise (AWGN) to the generated CS PHY waveform.
Receive the noisy waveform at the Reflector, and generate a response waveform.
Add propagation delay and AWGN to the generated response waveform.
Receive the noisy response waveform at the Initiator.
Visualize the time-domain CS PHY waveforms at the Initiator and Reflector.

Configure CS PHY and Simulation Parameters

Specify the noise power spectral density (Eb/No), samples per symbol, and the speed of light.

EbNo = 30;                                     % In dB
sps = 8;                                   
lightSpeedConst = physconst("LightSpeed");     % In m/s

Specify the PHY transmission mode.

phyMode = "LE1M";

Specify the operating mode for CS PHY waveform generation.

stepMode = 0;

Specify the type of optional sequence in the CS SYNC packet format.

sequenceType = "Sounding Sequence";

Specify the optional sounding sequence length.

sequenceLength = 32;       % In bits

Specify the duration of the CS tone.

toneDuration = 20;         % In microseconds

Specify the distance between the Initiator and the Reflector devices.

distance = randi([2 80],1,1);                 % In meters

Compute the waveform propagation time between the Initiator and Reflector devices.

propagationTime = distance/lightSpeedConst;   % In seconds

Calculate the sampling frequency (in Hz) of the generated waveform.

sampleRate = sps*1e6*(1 + 1*(phyMode=="LE2M")); % In Hz

Set the signal-to-noise ratio (SNR).

snr = EbNo - 10*log10(sps);

Create and configure a Bluetooth LE CS configuration object for the Initiator.

cfgObjectI = bleCSConfig(Mode=phyMode, ...
    SamplesPerSymbol=sps, ...
    DeviceRole="Initiator", ...
    SequenceLength=sequenceLength, ...
    SequenceType=sequenceType, ...
    StepMode=stepMode, ...
    ToneDuration=toneDuration);

Create and configure a Bluetooth LE CS configuration object for the Reflector.

cfgObjectR = bleCSConfig(Mode=phyMode, ...
    SamplesPerSymbol=sps, ...
    DeviceRole="Reflector", ...
    SequenceLength=sequenceLength, ...
    SequenceType=sequenceType, ...
    StepMode=stepMode, ...
    ToneDuration=toneDuration);

Create a variable fractional delay object by using the dsp.VariableFractionalDelay (DSP System Toolbox) System object™.

timeDelay = dsp.VariableFractionalDelay;

Specify the number of samples to delay, based on the distance between the Initiator and Reflector devices.

samplesToDelay = propagationTime*sampleRate;

Set the configuration to display the time-domain CS PHY waveform.

timeDomainScope = timescope(SampleRate=sampleRate, ...
    ChannelNames={'Initiator','Reflector'}, ...
    LayoutDimensions=[2 1]);
timeDomainScope.YLimits=[-1.25 1.25];
timeDomainScope.Title = "Initiator View";
timeDomainScope.ActiveDisplay = 2;
timeDomainScope.YLimits=[-1.25 1.25];
timeDomainScope.Title = "Reflector View";

Set the configuration to display the frequency spectrum of the generated CS PHY waveform.

frequencyScope = spectrumAnalyzer(SampleRate=sampleRate);

Simulate and Visualize CS PHY Waveforms

Generate the Bluetooth LE CS PHY waveform at the Initiator.

waveformInitI = bleCSWaveform(cfgObjectI);

Compute the length of the generated Bluetooth LE CS waveform.

packetLength = length(waveformInitI)

packetLength = 
352

Plot the Bluetooth LE CS waveform at the Initiator.

frequencyScope(waveformInitI)
release(frequencyScope)

Add propagation delay to the generated waveform.

delayWaveformI = timeDelay([waveformInitI; zeros(ceil(samplesToDelay),1)],samplesToDelay);

Specify the time-domain waveform at the Initiator.

initiatorView = [waveformInitI; zeros(ceil(samplesToDelay),1)];

Add AWGN to the delayed waveform.

noisyWaveformI = awgn(delayWaveformI,snr,"measured");

Specify the time-domain waveform at the Reflector.

reflectorView = noisyWaveformI;

Display the time-domain view of the CS PHY waveform at the Initiator and the Reflector.

timeDomainScope(initiatorView,reflectorView)
release(timeDomainScope)

The Reflector, upon receiving the CS waveform, completes the current task and then begins transmitting a response waveform (which might involve calculating processing delay).

Specify the idle wait time the Reflector must observe before initiating its response. Set the idle wait time of the Reflector by determining the number of frames it should wait.

idleFrames = randsrc(1,1,1:4);

Specify the number of idle samples of the Reflector in integer multiples of the received waveform.

idleSamples = idleFrames*packetLength;

Generate and plot the Bluetooth LE CS response waveform at the Reflector.

waveformInitR = bleCSWaveform(cfgObjectR);
frequencyScope(waveformInitR)
release(frequencyScope)

Specify the time-domain waveform at the Reflector.

reflectorView = [reflectorView; zeros(idleSamples,1); waveformInitR; zeros(ceil(samplesToDelay),1)];

Add propagation delay to the generated response waveform.

delayWaveformR = timeDelay([waveformInitR; zeros(ceil(samplesToDelay),1)],samplesToDelay);

Add AWGN to the delayed waveform.

noisyWaveformR = awgn(delayWaveformR,snr,"measured");

Specify the time-domain waveform at the Initiator.

initiatorView = [initiatorView; zeros(idleSamples,1); noisyWaveformR];

Display the time-domain view of the CS PHY waveform at the Initiator and the Reflector.

timeDomainScope(initiatorView,reflectorView)
release(timeDomainScope)

Compute Length of Bluetooth LE CS PHY Waveform

Open Live Script

Specify the operating step mode for CS waveform generation.

stepMode = 0;

Specify the duration of the CS tone.

toneDuration = 40;   % In microseconds

Specify the sequence type and sequence length of the optional field.

sequenceType = "Random Sequence";
sequenceLength = 128; % In bits

Specify the samples per symbol and PHY transmission mode.

sps = 8;
phyMode = "LE1M";

Specify the role of the Bluetooth LE device as "Reflector" or "Initiator".

deviceRole = "Reflector";

Calculate the length of the Bluetooth LE CS PHY waveform from the specified configuration.

multiFactor = 1 + 1*(phyMode=="LE2M");
lengthPreamble = 8*multiFactor;
lengthAccessAddress = 32;
lengthTrailer = 4;
lengthGaurdDuration = 10*multiFactor;
lengthTone = toneDuration*2*multiFactor; % One duration each for CS tone and extension slot

switch stepMode
    case 0
        lengthOfWaveform = sps*(lengthPreamble + lengthAccessAddress + lengthTrailer) + sps*(lengthGaurdDuration + 80)*(deviceRole=="Reflector");

    case 1
        lengthOfWaveform = sps*(lengthPreamble + lengthAccessAddress + lengthTrailer + sequenceLength*multiFactor);

    case 2
        lengthOfWaveform = sps*lengthTone;

    case 3
        lengthOfWaveform = sps*(lengthPreamble + lengthAccessAddress + lengthTrailer + sequenceLength*multiFactor + lengthGaurdDuration + lengthTone);
end

Create and configure a Bluetooth LE CS configuration object for the Reflector.

cfgChannelSounding = bleCSConfig(DeviceRole=deviceRole, ...
    Mode=phyMode, ...
    SamplesPerSymbol=sps, ...
    SequenceLength=sequenceLength, ...
    SequenceType=sequenceType, ...
    StepMode=stepMode, ...
    ToneDuration=toneDuration);

Generate the Bluetooth LE CS PHY waveform at the Reflector.

csPHYWaveform = bleCSWaveform(cfgChannelSounding);

Display the size and length of the generated waveform and note that both values are same.

numel(csPHYWaveform)

ans = 
1072

lengthOfWaveform

lengthOfWaveform = 
1072

Input Arguments

collapse all

`cfgChannelSounding` — Bluetooth LE CS PHY waveform configuration parameters
`bleCSConfig` object

Bluetooth LE CS PHY waveform configuration parameters, specified as a bleCSConfig object.

Output Arguments

collapse all

`csPHYWaveform` — Bluetooth LE CS PHY waveform
complex-valued time-domain waveform

Bluetooth LE CS PHY waveform, returned as a complex-valued time-domain waveform of the size Ns-by-1, where Ns specifies the number of received samples. This table shows how the value of Ns for the Initiator and Reflector devices depends on the values of the Mode, StepMode, ToneDuration and SamplesPerSymbol properties of the bleCSConfig object.

Value of `Mode`	Value of `StepMode`	Value of Ns (Initiator)	Value of Ns (Reflector)
`"LE1M"`	`0`	`SamplesPerSymbol` × 44	`SamplesPerSymbol` × (44 + GD + `ToneDuration`)
	`1`	`SamplesPerSymbol` × (44 + `SequenceLength`)	`SamplesPerSymbol` × (44 + `SequenceLength`)
	`2`	`SamplesPerSymbol` × `ToneDuration` × 2	`SamplesPerSymbol` × `ToneDuration` × 2
	`3`	`SamplesPerSymbol` × (44 + `SequenceLength` + GD + (`ToneDuration` × 2))	`SamplesPerSymbol` × (44 + `SequenceLength` + GD + (`ToneDuration` × 2))
`"LE2M"`	`0`	`SamplesPerSymbol` × 52	`SamplesPerSymbol` × (52 + (GD × 2) + (`ToneDuration` × 2))
	`1`	`SamplesPerSymbol` × (52 + `SequenceLength`)	`SamplesPerSymbol` × (52 + `SequenceLength`)
	`2`	`SamplesPerSymbol` × `ToneDuration` × 2 × 2	`SamplesPerSymbol` × `ToneDuration` × 2 × 2
	`3`	`SamplesPerSymbol` × (52 + `SequenceLength` + (GD × 2) + (`ToneDuration` × 2 × 2))	`SamplesPerSymbol` × (52 + `SequenceLength` + (GD × 2) + (`ToneDuration` × 2 × 2))

GD is the guard time in the CS SYNC packet. Regardless of the Mode value you specify, the value of GD is 10 microseconds.

The ToneDuration value specifies the duration of the CS tone in microseconds. This table shows how the value of ToneDuration depends on the value of the StepMode property.

Value of `StepMode`	Value of `ToneDuration`
`0`	`80`
`1`	Not applicable
`2`	`10`, `20`, or `40`
`3`	`10`, `20`, or `40`

The value of SequenceLength specifies the length of the sequence in the optional field of the CS SYNC packet. You can set the type of sequence in the optional field by configuring the SequenceType property of the bleCSConfig object as "Sounding Sequence" or "Random Sequence". This table shows how the value of SequenceLength depends on the value of the SequenceType property.

Value of `SequenceType`	Value of `SequenceLength`
`"Sounding Sequence"`	32 or 96
`"Random Sequence"`	32, 64, 96, or 128

Because the data rate in LE2M is double that of LE1M, the function uses a multiplicative factor of 2 to compute the value of Ns at the Initiator and Reflector.

Data Types: double

`accessAddress` — Access address generated from CS DRBG function
32-bit column vector

Access address generated from the CS DRBG function, returned as a 32-bit column vector. For more information about the access address and its selection rules, see Sections 3.13.4 and 3.13.5 of [2].

Data Types: double

References

[1] Bluetooth Technology Website. “Bluetooth Technology Website | The Official Website of Bluetooth Technology.” Accessed June 22, 2024. https://www.bluetooth.com/.

[2] Bluetooth Core Specifications Working Group. "Bluetooth Core Specification" v6.0. https://www.bluetooth.com/specifications/specs/core-specification-6-0/.

Version History

Introduced in R2024b

bleCSWaveform

Syntax

Description

Examples

Generate and Visualize Bluetooth LE Channel Sounding PHY Waveform

Compute Length of Bluetooth LE CS PHY Waveform

Input Arguments

`cfgChannelSounding` — Bluetooth LE CS PHY waveform configuration parameters
`bleCSConfig` object

Output Arguments

`csPHYWaveform` — Bluetooth LE CS PHY waveform
complex-valued time-domain waveform

`accessAddress` — Access address generated from CS DRBG function
32-bit column vector

References

Version History

See Also

Functions

Objects

Topics

bleCSWaveform

Syntax

Description

Examples

Generate and Visualize Bluetooth LE Channel Sounding PHY Waveform

Compute Length of Bluetooth LE CS PHY Waveform

Input Arguments

cfgChannelSounding — Bluetooth LE CS PHY waveform configuration parameters bleCSConfig object

Output Arguments

csPHYWaveform — Bluetooth LE CS PHY waveform complex-valued time-domain waveform

accessAddress — Access address generated from CS DRBG function 32-bit column vector

References

Version History

See Also

Functions

Objects

Topics

`cfgChannelSounding` — Bluetooth LE CS PHY waveform configuration parameters
`bleCSConfig` object

`csPHYWaveform` — Bluetooth LE CS PHY waveform
complex-valued time-domain waveform

`accessAddress` — Access address generated from CS DRBG function
32-bit column vector