Ability to set SNR (related to pathloss)

[artiommocrenco]

Ability to set SNR (related to pathloss)

[GUVWAF]

Hi,

SNR is calculated based on the RSSI and a noise level, which you can configure in config.py, but it is assumed to be the same everywhere. RSSI is calculated based on the pathloss model, the distance between each node, their transmit power (which is the same for each node and based on the region you set), and antenna gain. You can specify the antenna gain for each node when you place them.

Hope this helps.

[artiommocrenco]

Hi,

SNR is calculated based on the RSSI and a noise level, which you can configure in config.py, but it is assumed to be the same everywhere. RSSI is calculated based on the pathloss model, the distance between each node, their transmit power (which is the same for each node and based on the region you set), and antenna gain. You can specify the antenna gain for each node when you place them.

Hope this helps.

Ah thanks so much, the reason why I'm asking is because in firmware I found that delay before flooding a message is dependant on SNR, and there also is some randomness

[GUVWAF]

Yes, indeed. The simulator calculates this as well:

Meshtasticator/lib/mac.py

Lines 19 to 36 in f67084f

	def getTxDelayMsecWeighted(node, rssi): # from RadioInterface::getTxDelayMsecWeighted
	snr = rssi-conf.NOISE_LEVEL
	SNR_MIN = -20
	SNR_MAX = 15
	if snr < SNR_MIN:
	verboseprint('Minimum SNR at RSSI of', rssi, 'dBm')
	snr = SNR_MIN
	if snr > SNR_MAX:
	verboseprint('Maximum SNR at RSSI of', rssi, 'dBm')
	snr = SNR_MAX
	CWsize = int((snr - SNR_MIN) * (CWmax - CWmin) / (SNR_MAX - SNR_MIN) + CWmin)
	if node.isRouter == True:
	CW = random.randint(0, 2*CWsize-1)
	else:
	CW = random.randint(0, 2**CWsize-1)
	verboseprint('Node', node.nodeid, 'has CW size', CWsize, 'and picked CW', CW)
	return CW * slotTime

[artiommocrenco]

Thank you so much!

[artiommocrenco]

This is very helpful to simulate the mesh we have here in Moldova, Chisinau

[GUVWAF]

Great to hear! I'll close this issue now. Feel free to open another if you have further questions.