lora.predavanje

LoRa
	SX Chips from Semtech for different frequencyes
	EU uses 868 Band 
		Air time limits
        SX1276	
	Great in noisy envirement
	Gateway SX1301/SX1308 for gateway 
		8 bands at the same time
		better sensitivity
	LoRa is IP block that describes modulation LoRa PHY
	Propriatary modulation :(
	SPI controlled chip
	Node chips SX1276
	Check gr-LoRa on git
		https://github.com/BastilleResearch/gr-lora
	Chrip spread spectrum
		helps to get signal from noise better
	868 is license free band
	125kHz bandwith
        https://www.disk91.com/2017/technology/internet-of-things-technology/all-what-you-need-to-know-about-regulation-on-rf-868mhz-for-lpwan/
        https://i2.wp.com/www.disk91.com/wp-content/uploads/2017/01/Diapositive12.png?w=720&ssl=1
        https://i2.wp.com/www.disk91.com/wp-content/uploads/2017/01/ResauxLowPower.png?w=720&ssl=1	   

LoRaWAN
	Half-Duplex comunication - ransmission of data in just one direction at a time (walkie-talkie) 
	ISM bands 915 US 868 in EU
        In EU you can send only 1% of time on some frequencyes 0.1%
        One band 10% of time
	360 sec in hower
	Class A 
		Sends Opens RX1 Opens RX2 Got to sleep
	Class B 
		Sends and receives in adjusted time slots
	Class C 
		Sends Opens RX1 waits with opened RX2 
	Two way comunication - gateway has same air time limits as node - you can use 10% band for downllink
	Sends back message on same frequency message has arrived RX1, or on specila frequency RX2
	LoRaWAN is a media access control (MAC) protocol for wide area 
	networks. It is designed to allow low-powered devices to
	communicate with Internet-connected applications over long range 
	wireless connections.
	It is Encrypted
	Two way to attach to a network
	Two keys one for network server and one for data(application)
	OTAA
		Handshaking
		Device sends request
		Gateway calculate sesion key
		Node calculate sesion keys
			Note that no key is sendt by node nor by gw
		Gateway send accept with new keys

	ABP Autorisation by persolanalisation
		On bouth sides you set sesion key
		
	Not for lot of data, and not for time critical data

	Listen Before Talk
		The Listen Before Talk (LBT) protocol makes it possible for multiple users to share the same channel. 
		When LBT is enabled, the device continuously monitors channels so as to transmit only when a channel is not in use.

Gateway is just Forwarder  just forwarding messages from NODE <> Network
	Packet forwarder - runs on node

Servers

Gateway bridge
	Packet FW <> GW bridge
Network server brocar
Application serer brocar

or use TTN - v3 should be easyer to deploy

LPWAN not narrow band
Low datarate
High range
Great battery life

Spec
Range
LoW Power
LPWAN Low Power Wide Area Network
LoRa is all about compromise
DR - RANGE - POWER

TTNZagreb by radiona
Two workshops for now
	Build you gw
	All about nodes - mapping the city

Coverage of our gateways
	TTN mapper
		Not opensource
	check lemilica.com for opensource solution

Use case
	IRNAS has few great ones
		Count pinguins
			power on
			take pic
			opencv count pinguins
			lora send no of pinguins
			power off
		Pit stop for turtles
		Trap for pouchers
	Bird house
		Bird in - temp
	Intrudes alarm on some distant place - or boat...
	Public scale
		On exibition - visit us @
	Pager
	GPS for pets
	Polution detector
		If something bad detected send warning
	Agriculture
	Distant plant soil moisture

	So many other

Warning:
	Do not put yout GW near working chimney