Friday, May 22, 2015

Lora Network Coverage

Espotel LoRa network covers most of Espoo populated area with cell diameter of 20 km. Tested performance exceeds initial estimation.

Once the gateway passed solar powered test period, it was erected to it's final position at the highest point at roof-top of Espotel HQ, some 6 meters higher than previously in a more difficult to reach location some 15-20 meters above the ground.

Now more comprehensive network coverage test was performed. The testing focused on uplink performance. Results with distances from the gateway:
  • 10 km - Stationary nodes in good position with proper antenna
  • 7.5 km - Vehicle mount with external antenna
  • 5 km - Indoor coverage with dipole antenna
  • 2.5 km - Indoor coverage with integrated antenna
Espotel LoRa network coverage.
The network covers majority of the city of Espoo with more than 90% of it's population. Communication is possibly also in western parts of Helsinki downtown and from tall buildings further away. The map indicates circles with radius of 10km, 7.5km, 5km and 2.5km. 

868 MHz half-wave dipole antenna with magnetic mount at car roof-top.
Testing was performed using standard type 868 MHz half-wave dipole antenna mounted at vehicle roof-top with magnetic mount. Multitech mDot Lora-module was used with default parameter configuration.

Within distance from 7,5 to 10 km it was possible to communicate from car to the gateway every now and then, but in practice the reasonable maximum distance is about 7,5 km due to increased packet-loss ratio while distance increases.

Espotel engineer installing the gateway in it's new location.

Thursday, May 7, 2015

First LoRa network now open

Espotel has released first open LoRa network in Finland for developers' and hackers' use.

The first gateway is located at the roof of Espotel HQ in southern Espoo.The network is intended for promoting LoRa RF technology and is open and free of charge for all development and test purposes. The gateway will be open for limited period of time and closed down when commercial public networks are available or winter blocks the energy source of the gateway, which ever comes first.

Solar powered LoRa gateway at the roof of Espotel HQ.
The gateway is solar powered in order to emphasis the low power nature of LoRa RF technology. The gateway has solar cell with 50W nominal power and 75 Ah battery that provides run time of one week without sun. That's necessary as the weather in Finland is often cloudy and there may be number of rainy days in a row.

At the moment the gateway is not at the highest possible location but in easy to access location, due to test run period ongoing to see whether the solar cell capacity is high enough. Even if the sun may shine in Finland up to 24h per day at Summer time, it's most of the time shining from wrong direction to the panel. Motorized panel with 360 degree rotation capability would be needed to utilize the full potential of mid-night sun.

I performed the first signal strength test Today while driving home from the office. With LoRa node in my car, I got signal transmitted some 6 km away from the gateway. The node had +14dBm TX power and quarter-wave dipole antenna. Once the gateway antenna will be erected some 5 more meters after solar cell test run, the initially expected 7 km range is most likely. More detailed network coverage map will be published later.

Location of gateway and most distant location from where signal was detected. 7km radius is marked with blue circle.
The gateway is connected to the internet with 3G/4G cellular data modem, and delivers all received data to IBM IoT Foundation and further to Bluemix. From there the data is available either with WebSocket, HTTP or MQTT interface. Tell me your device details and I'll give you access to your data. Currently only upstream data is supported for simplicity sake.

The gateway conforms with LoRaWAN 1.0 specification and LoRa devices are required to do so. Network key, application key and encryption are not defined, all devices and connections are accepted. If you have a cool project in mind, we may even sponsor you some LoRa hardware. Just contact me by email.

Happy hacking!