End to End Bluetooth and WLAN simulation

I am trying to generate spectrograms of coexisting Bluetooth and WLAN packets. Task required to have multiple transmitters, one receiver, path loss and AWGN noise. MATLAB offers some related examples,

https://au.mathworks.com/help/comm/ug/End-to-end-Bluetooth-BR-EDR-PHY-Simulation-with-WLAN-Interference-and-Adaptive-Frequency-Hopping.html

https://au.mathworks.com/help/comm/ug/End-to-end-BLE-PHY-Simulation-Using-PathLoss-Model-RF-Impairments-and-AWGN.html

However, they both cannot be directly used for the required purpose due to two reasons.

1. The first example considers continuous WLAN interference where as I need random WLAN packets (spreaded across the spectrogram)
2. The second example provides only one bluetooth packet, where as I need multiple packets spreaded across the spectrogram

I tried adopting components from both examples to do what I need, however I face below problems

1. nextHop funtion in MATLAB gives the channel index for next hop and it is used as an input to the bleWaveformGenerator function. However the output from bleWaveformGenerator does not contain the required carrier (center) frequency. All the packets are centered around 0 Hz.

The main file is copied below. This will need multiple support files from MATLAB-->examples-->bluetooth--->main

% Trying to spread bluetooth packets across the spectrogram and then add

% WLAN packets

commSupportPackageCheck('BLUETOOTH');

pathLossModel = 'Free space'; % Path loss model

rxSensitivity = -70 ; % Receiver sensitivity in dBm

txPower = 0; % Transmit power in dBm

txAntennaGain = 0; % Transmitter antenna gain in dB

rxAntennaGain = 0; % Receiver antenna gain in dB

linkMargin = 15; % Link margin(dB) assumed in the simulation

channelIndex=0;

samplesPerSymbol = 88;

symbolRate = 1e6;

sampleRate = symbolRate*samplesPerSymbol;

% samplesPerSymbol = 8; % Samples per symbol

dataLen = 254; % Data length in bytes

phyMode = 'LE1M'; % PHY transmission mode

% Default access address for periodic advertising channels

accessAdd = [0 1 1 0 1 0 1 1 0 1 1 1 1 1 0 1 1 0 0 1 0 0 0 1 0 1 1 1 0 0 0 1]';

slotValue = 1*2;%phyTx.slotsRequired(packetType)

inputClock = 0;

clockTicks = slotValue*2;

numSlots=20;

numMasterTxSlots = floor(numSlots/slotValue);

hopIndex = zeros(1, numMasterTxSlots);

% Index to hop index vector

hopIdx = 1;

fh = bluetoothFrequencyHop;

fh.SequenceType = 'Connection basic';

scope2 = dsp.SpectrumAnalyzer(...

'ViewType','spectrogram', ...

'SpectrumType','Power density', ...

'TimeResolutionSource','Property', ...

'TimeResolution',0.0005, ...

'SampleRate',sampleRate, ...

'TimeSpanSource','Property', ...

'TimeSpan', 0.05, ...

'FrequencyResolutionMethod', 'WindowLength', ...

'WindowLength', 512, ...

'AxesLayout', 'Horizontal',...

'FrequencyOffset',(2402+channelIndex)*1e6);

sprev = rng('default'); % Set random number generator seed

rx=[];

for slotIdx = 0:slotValue:numSlots-slotValue

% % Update clock

inputClock = inputClock + clockTicks

% Frequency hopping

[channelIndex,~] = nextHop(fh,inputClock);

channelIndex=round(channelIndex/2)

txBits = randi([0 1],dataLen*8,1,'int8');

fc = (2*channelIndex+2402)*1e6; % Center frequency in Hz

txWaveform = bleWaveformGenerator(txBits,'Mode',phyMode,...

'SamplesPerSymbol',samplesPerSymbol,...

'ChannelIndex',channelIndex,...

'AccessAddress',accessAdd);

NF = 6; % Noise figure (dB)

T = 290; % Ambient temperature (K)

dBm2dBFactor = 30; % Factor for converting dBm to dB

% Symbol rate based on the PHY transmission mode

symbolRate = 1e6;

if strcmp(phyMode,'LE2M')

symbolRate = 2e6;

end

BW = samplesPerSymbol*symbolRate; % Bandwidth (Hz)

k = 1.3806e-23; % Boltzmann constant (J/K)

noiseFloor = 10*log10(k*T*BW)+NF; % Nosie floor in dB

% Measure signal power at the receiver based on the receiver sensitivity and

% assumed link margin

measuredPowerVector = rxSensitivity - dBm2dBFactor+linkMargin;

snrdB = measuredPowerVector - noiseFloor; % SNR in dB

% Create and configure the System objects for impairments

initImp = helperBLEImpairmentsInit(phyMode,samplesPerSymbol);

% Configure RF impairments

initImp.pfo.FrequencyOffset = 5800; % Frequency offset in Hz

initImp.pfo.PhaseOffset = 5; % Phase offset in degrees

initoff = 0.15*samplesPerSymbol; % Static timing offset

stepsize = 20*1e-6; % Timing drift in ppm, Max range is +/- 50 ppm

initImp.vdelay = (initoff:stepsize:initoff+stepsize*(length(txWaveform)-1))';

initImp.dc = 20; % Percentage related to maximum amplitude value

% Pass generated BLE waveform through RF impairments

txImpairedWfm = helperBLEImpairmentsAddition(txWaveform,initImp);

% Obtain the path loss value in dB

pldB = txPower-dBm2dBFactor+rxAntennaGain+txAntennaGain-measuredPowerVector;

plLinear = 10^(pldB/20); % Convert from dB to linear scale

% Attenuate BLE waveform

attenWaveform = txImpairedWfm./plLinear;

% Add WGN to the attenuated BLE waveform

rxWaveform = awgn(attenWaveform,snrdB,'measured');

% Create and configure the receiver System objects

initRxParams = helperBLEReceiverInit(phyMode,samplesPerSymbol,accessAdd);

% Recover data bits using practical receiver

[rxBits,accessAddress] = helperBLEPracticalReceiver(rxWaveform,initRxParams,channelIndex);

% Obtain BER by comparing the transmitted and recovered bits

ber = [];

if(length(txBits) == length(rxBits))

ber = (sum(xor(txBits,rxBits))/length(txBits));

end

% Estimate the distance between the transmitter and the receiver based on the path loss value and the environment

if any(strcmp(pathLossModel,{'Free space','Log distance','Log normal shadowing'}))

% Center frequency is required only for these path loss models

distance = helperBluetoothEstimateDistance(pathLossModel,pldB,fc);

else

distance = helperBluetoothEstimateDistance(pathLossModel,pldB);

end

hopIndex(hopIdx) = channelIndex;

hopIdx = hopIdx + 1;

scope2(rxWaveform);

pause(0.01);%original 0.01

end

Answer 1

[Vamsi Manthini]

Hello,

“The first example considers continuous WLAN interference, whereas I need random WLAN packets spread across the spectrogram. The second example provides only one Bluetooth packet, whereas I need multiple packets spread across the spectrogram.”

• To address these requirements, please have a you look at the Simulate Noncollaborative Coexistence of Bluetooth LE, Bluetooth BR/EDR, and WLAN Networks and Noncollaborative Bluetooth LE Coexistence with WLAN Signal Interference examples. These examples allow you to generate random WLAN packets and configure different application data rates and packet sizes at Bluetooth nodes enabling multiple packets of various sizes in your simulation. Both examples are system-level simulations modelling nodes comprising the LL/Baseband and PHY layers of the Bluetooth protocol stack.
• Alternatively, if you prefer a PHY-only simulation for the same, you can refer to PHY Simulation of Bluetooth BR/EDR, LE, and WLAN Coexistence.

“nextHop funtion in MATLAB gives the channel index for next hop and it is used as an input to the bleWaveformGenerator function. However the output from bleWaveformGenerator does not contain the required carrier (center) frequency. All the packets are centered around 0 Hz”

• The output channel index from the nextHop function is used for Bluetooth BR/EDR waveforms, not for Bluetooth LE waveforms. To generate a Bluetooth BR/EDR signal using the generated channel index of nextHop function, use bluetoothWaveformGenerator instead of bleWaveformGenerator. Please try this in your script for the desired results.

Thank you,

Vamsi M