Lora & LoraWan:
Lora is actually a unique proprietary modulation format (phi layer). Semtech is the owner of the Lora RF technology and they give licenses to others.
LoraWan (MAC layer ) is an open standard maintained by Lora Alliance
Lora is actually a unique proprietary modulation format (phi layer). Semtech is the owner of the Lora RF technology and they give licenses to others.
LoraWan (MAC layer ) is an open standard maintained by Lora Alliance
RF basics of Lora :
- A Lora Signal starts with a preamble signal & has a constant ramp chirp inside.
- The number symbols in a preamble signal = number of chirps/number of peaks of the ramp signal.
- Lora has the ability to demodulate several orthogonal/simultaneous signals at the same time. this function is implemented in the gateway chips like SX1301 where all the nodes connect.
- LoRa RF physical layer uses a form of spread spectrum modulation.
- To maximize battery lifetime or to maximize signal transmission distance the transmission power level used in the Lora chip can be decreased or increased.
- The communication between different end-devices and gateways can be on several different frequency channels and they can use different data rates.
- The use of the chirp spread spectrum technology enables communications with different data rates not to interfere with each other. In this way, a set of "virtual" channels can be created which increases the capacity of the gateway.
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| Signal-Detection |
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| Signal Demodulate |
Frequency and bandwidth:
The LoRa wireless system makes
use of the unlicensed frequencies that are available worldwide. The most widely
used frequencies/bands are:
- 868 MHz for Europe
- 915 MHz for North America
- 433 MHz band for Asia
back In August 2015, the GSMA
(Groupe Speciale Mobile Association)—a group made up of mobile
operators—announced that it plans on standardizing LPWAN technology on a
licensed spectrum by early 2016. This push has received endorsements and
backing from companies like“AT&T, Bell Canada, China Mobile, China Telecom,
China Unicom, Deutsche Telekom, Etisalat, KDDI, NTT DOCOMO, Ooredoo, Orange,
Singtel, Telecom Italia, Telefonica, Telenor, Telstra, and Vodafone,”
but still, it has not got licensed because of some technical challenges which we will talk about later.
In Lora low data rates are used, because of low data rates, low bandwidths are required.A variety of bandwidths are available: 7.8 kHz; 10.4 kHz; 15.6 kHz; 20.8 kHz; 31.2 kHz; 41.7 kHz; 62.5 kHz; 125 kHz; 250 kHz; 500 kHz . this bandwidth can be selected upon link condition and data rate
The Lora Network Diagram :
Node:
The nodes are the sensing elements. Nodes to Gateway is typically a star-topology.
Communication to endpoint nodes is generally bi-directional, but it is also possible to support multicast operation, and this is useful for features such as software upgrades and the like or other mass distribution messages. Nodes can be of the following types
- Class A - bi-directional end-devices
- Class B - bi-directional end-devices with scheduled receive slots
- Class C - bi-directional end-devices with maximal receive slots
The gateway receives the packets from the LoRa nodes/ endpoints and then transfers them onto the network server. This part of can be Ethernet, cellular, wifi or any other telecommunications link wired or wireless. The gateways are connected to the network server using standard IP connections. In this way the data uses a standard protocol, LoRa gateways may often be co-located with a cellular base station.
Gateways within the same network require synchronization. Communication between end devices and gateways is spread out on different frequency channels and data rates. The selection of the data rate is a trade-off between communication range and message duration.
Network Server: One of its core responsibility is to eliminate duplicate packets.The network server can manage the data rate and RF output for each end device individually by means of an adaptive data rate (ADR) scheme that is typically updated once every 24 hours
Application Server: is truly dependent upon your application
Possible Application areas :
·
Smart Parking
· Environmental monitoring & Agriculture
·
Waste management
·
Street Lightning
·
Asset tracking
·
Postpaid based Utility meters mainly water and gas meters
·
Flood monitoring
·
Railway Level crossing
·
Interesting
projects around Lora:
- Maybe CISCO is making home based router that will have Lora module inside may be the router will work as a gateway
- Amsterdam Beacon Mile https://www.youtube.com/watch?v=w7yF1ONDp7A
- UK Calderdale Flood Sensor Network https://www.youtube.com/watch?v=TxMpNsS-oro [built by things network hardwares]
The All wanted Location tracking topic:
Geolocation is a part of the Lora Standard . and sagemcom is a company working on it.
Basically, At the physical layer, the radio signal used by LoRa is somewhat close to a radar signal, thanks to its Chirp Spread Spectrum (CSS) technology. The antenna Gateway can very precisely detect the arrival of the signal emitted from the device, it was explained by Thierry Listable.
By DTOA (difference time of arrival) technology the base station can record the time of arrival of the signal from the device and a position is calculated from that. Obviously, static position is appropriate for the case of Lora
Semtech says resolution could be from 10m to 100m but Sagemcom says it could be more precise and they are working on a protocol named femtoLora
A company named iota tracker has already announced a product based on it
ref:
http://www.iotatracker.com/howitworks
https://www.youtube.com/watch?v=x4Ic92efLY8
To use it you need to buy their Home base station which is actually a compact gateway, maybe they won't create the network by increasing the number of users.
LinkLabs has a statement on this topic to https://www.link-labs.com/lora-localization/ I assume it could be a market hype only So this topic needs more study obviously.
Security of Lora Wan:
you can listen to this talk regarding the security of Lora
https://www.youtube.com/watch?v=iZOfGGCw90M
Lora Chip
manufactures: (Node)
semtech ships are lower in
price than microchip
Gateway:
·
CISCO 910 industrial router http://www.cisco.com/c/en/us/products/collateral/routers/900-series-industrial-routers/datasheet-c78-732129.html
its obvious that new technology devices cost would be
very much so The Things network has come up with lora products which are
comparatively low . its all open software and open hardware but its actually
for development and these are based on Microchip’s Lora modules
· similarly Froggyfactory sells development alike devices like
the things network based on semtech chips
Lora
based LPWAN solution Selling Companies: these companies are selling
network services (Server + Application server) part of LoraWan
Technical challenges of Lora
I think the cost and hassle to build and maintain the network infrastructure is what that will prevent Lora from acquiring mass acceptance . Sigfox or NB-IOT will solve this problem as network operator it self will build & support the sub GHz infrastructure along with their 3G/4G cellular services. So now lets see what the future holds for the LPWAN market
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