ISM 868 band and the duty cycle

  • 10 augustus 2016
  • 4 reacties
  • 4177 keer bekeken

Reputatie 2
Badge +1
This post has become obsolete as it was incorporated in the Uplink and Downlink messages and the Duty Cycle topic.

ISM868 regulations



In Europe LoRa uses unlicensed frequency spectrum in 868 MHz band (ISM). Devided in sub-bands between 863 and 870 Mhz. Everyone is allowed to use this spectrum, but has to obey restrictions determined and enforced by the government per ISM (sub)-band. Generally speaking:
  • Devices are not allowed to exceed a maximum power output of 14 dBm (25 mW)
  • Devices are only allowed a limited time-on-air (time it is sending). This duty-cycle is maximum 1% of an hour for that sub-band.
LoRa devices are allowed to use different ISM Bands independently, therefore increasing the time on air allowed. Which channels in which band are used are set by KPN.

LoRaWAN specifies that each time a message is send in one ISM subband, the device must wait the remaining time of the duty cycle in that band before resending (For time on air of 0.5s and 1% duty-cycle, this means waiting 49,5s).

To enforce regulations, KPN requires all devices to be certified for LoRa, see Certification of LoRa devices. Or use standard certified LoRa chips. These chips know how to handle the different channels and duty cycle and will respond with an error when a user tries to send a message too soon.

Downlink & Duty-Cycle


Within ISM bands, gateways are also seen as one device, so duty cycle applies to the gateways as well. For receiving uplink messages from devices, no regulatory limit applies, but for downlink messages the gateway has to obey the Duty Cycle. Downlink capacity is increased by sending on a low SF, changing sub-bands and setting up gateways in area’s with many LoRa Devices. Nevertheless, the downlink capacity stays limited. Developers should design their solution with a minimum number of downlink messages. LoRa Acknowledgements are also downlink messages.

[color=green]

Usefull links

[/color]
- [color=#094ab1]LoRa:[/color] Starters Guide
- [color=#094ab1]LoRa:[/color] Geolocation
- [color=green]FAQ:[/color] Frequently Asked Questions
- [color=green]Tools:[/color] www.LoRaTools.nl

4 reacties

Reputatie 1
Badge

LoRaWAN specifies that each time a message is send in one ISM subband, the device must wait the remaining time of the duty cycle in that band before resending (For time on air of 0.5s and 1% duty-cycle, this means waiting 49,5s).


Explicit duty cycle limitation implementation description for EU868Mhz was removed from LoRaWAN specification.
There are no explicit changes in the duty cycle limitations. The information as provided by Michiel in the original post remain applicable.
What has been changed is that the regional parameters have been put in a different Alliance document.

LoRaWAN Specification

The LoRaWAN Specification document describes the LoRaWAN™️ network protocol including MAC layer commands, frame content, security, flexible network frequency management, device EIRP and TX dwell time, power control, relay protection and more.

LoRaWAN Regional Parameters V1.0

The LoRaWAN Regional Parameters document contains the channel frequency plans for various global regions. These details are managed separately from the LoRaWAN Specification to enable the Alliance to quickly address regional regulatory support requirements.
Reputatie 1
Badge
Please see LoRaWAN™️ Specification V1.0.2, chapter 21 ("Revisions") ,
Page 67 lines 23, 24 :
"Removed explicit duty cycle limitation implementation in the EU868Mhz ISM band (chapter7.1)"

You may also take a look at LoRaWAN™️ Specification V1.0, article 7.1.2, EU863-870 ISM Band channel frequencies, and compare it with chapter 2.1.2 EU863-870 ISM Band channel frequencies of LoRaWAN™️ Regional Parameters V1.0.

You'll see that the following paragraphs (page 34, lines 20-30 in LoRaWAN™️ Specification V1.0) were removed in recent versions of the spec:
"The LoRaWAN enforces a per sub-band duty-cycle limitation. Each time a frame is transmitted in a given sub-band, the time of emission and the on-air duration of the frame are recorded for this sub-band. The same sub-band cannot be used again during the next Toff seconds where:
.........
During the unavailable time of a given sub-band, the device may still be able to transmit on another sub-band. If all sub-bands are unavailable, the device has to wait before any further transmission. The device adapts its channel hoping sequence according to the sub-band availability.
Example: A device just transmitted a 0.5 s long frame on one default channel. This channel is in a sub-band allowing 1% duty-cycle. Therefore this whole sub-band (868 – 868.6) will be unavailable for 49.5 s. "

That's what I was talking about, sorry for not being clear enough.

Thanks and with best wishes...

ISM868 regulations


In Europe LoRa uses unlicensed frequency spectrum in 868 MHz band (ISM). Devided in sub-bands between 863 and 870 Mhz.


Does KPN support all these sub-bands?

Reageer