What is the realistic range of LoRaWAN?

  • I wanted to gather your experiences with LoRaWAN ranges. I have tried with the FiPy and Dragino LoRa Shield, together with Dragino single-channel and multi-channel gateways. Within a European urban environment (no tall buildings, but houses and trees scattered around), I don't get more than 250m. How are your experiences?

  • Global Moderator

    @jcaron said in What is the realistic range of LoRaWAN?:

    So if you have both antennas exactly vertical and exactly at the same height, you do get the 15 dB gain. But if the one antenna is even slightly higher or lower than the other, the gain very quickly drops, and even becomes negative in some directions. Here's an example (different frequency, but the principle is most certainly the same):

    Thanks for the reply, I did not know such antennas actually existed! Generally its cheap Alixpress crap that oversells itself and actually has worse SWR than a piece of wire for the specified frequency range.

    Indeed you have to be wary of the antenna heights with such narrow beams

  • @Gijs I was surprised by the 15 dBi omni antenna mentioned by @chrpal a couple of weeks ago, my first impression was that an omnidirectional antenna was always in the 2-3 dBi range and that such high gain antennas were directional.

    But 15 dBi omnidirectional antennas do exist. They are indeed omnidirectional in the sense that they send/receive nearly equally in all directions along the perpendicular plane (like any omni antenna). But they are also "directional" in the sense that their beam is very very narrow (about 10° above/below that plane), where a 2.2 dBi omni will have a pretty wide beam.

    So if you have both antennas exactly vertical and exactly at the same height, you do get the 15 dB gain. But if the one antenna is even slightly higher or lower than the other, the gain very quickly drops, and even becomes negative in some directions. Here's an example (different frequency, but the principle is most certainly the same):

    ba170f26-b4c9-4c95-b74d-a561e19c21a1-image.png http://www.linkdataguard.com/images/Wireless/Antennas/TL-ANT2415D/Radiation-Patterns.jpg

    You can see at all around 360° horizontally it's very close to 15 dB (slight drop between 225° and 315°), but vertically, you're close to 0 dB at less than 10° below horizontal, and there are many places where gain is null or negative.

    There's no magic: an antenna can only have gain by "focusing" what it sends in a small part of the sphere around it. Most high-gain antennas will reduce the beam both vertically and horizontally (and thus becomes directional). These only do it in one dimension.

  • @Gijs said in What is the realistic range of LoRaWAN?:

    I'm not exactly sure of the Pycom supplied antenna

    The Pycom antenna is a half wavelength antenna. @jmarcelino once took one apart (removed the plastic) and then one could see that it was fed almost in the middle of the antenna with wl/4 above and < wl/4 below the feeding point.

    Also, 0dBi antennas do not exist,

    You're right. It is a simple ground plane antenna. The data sheet says nothing (0) about gain, so it's likely consistent with the theory of about 3 dB. But I do not care about being something between 0 and 3 dB, given the sensitivity budget of >120dB of LoRa. There is always some additional loss in the cables and the connectors.

  • Global Moderator

    @smbunn64 I'd really like to learn more about your 15dBi gain omni whip antenna. You either have an omni-directional antenna (a monopole or dipole) or a 15dBi (i for 'relative to isotropic') directional antenna (with high directionality in a certain direction). I do not think that a 1.5m long antenna 'wire' is in any way advantageous to your antenna setup. Most dipole antennas are 1/4 wavelength on each pole, so for 868MHz, that would be 8-9cm * 2 . Im not exactly sure of the Pycom supplied antenna

    Also, 0dBi antennas do not exist, (if only, that would be a real isotropic antenna and you'd have a nobel price on your hands :) ) you probably have a dipole at 2.15dBi, or 0dBd (relative to dipole)

    The thing about antenna gain is that it does not work like amplifier gain, where more is generally better. Gain is proportional to directionality, where when you have more reception in one area, you lose it in another. If you have the main lobe pointed up to the sky, you will get almost no reception from the ground. If it is truly a 15 dBi gain antenna, check its datasheet for the radiation characteristics and use it accordingly :)

    Let me know if that was clear to you

  • @smbunn64 you definitely have an issue somewhere in your setup. Even in pretty bad indoor-to-indoor conditions we’ve managed better than that.

    You should probably double-check your connections and settings. On the LoPy for instance, is the antenna connected to the right port in the board?

    Also remember that as stated in my post above, a high gain omni only has high gain in the plane perpendicular to the antenna at the level of the antenna. It quickly moves to no gain or extremely negative gain as soon as you exit the very narrow horizontal beam, for instance if you are at ground level while the antenna is several meters higher.

    You may be better off with a “regular” omni (gain around 2.2 dBi or so) which will have a wider beam vertically.

  • @smbunn64 DO you really mean m not km in your post? If yes, then there is something seriously wrong with your set-up. In my tests even with a

    0 dB gain antenna, with
    a gateway indoors and
    in a suburban area with smaller and larger houses

    I got receive distances between 500m and 2500m, depending on how many buildings are in the line of sight. The signals of the test nodes were also picked up by a gateway 7 km away with an antenna similar to yours and placed similar, albeit no on a hill, but on the roof of a large house.
    If you look at the gateway log at the TTN server, do you see packets from other nodes? You should receive some. Although I must confirm that with my node the other traffic is pretty low, like about 400 messages/day and a channel usage of 0.5 percent for the busiest node.

  • I have a Things Gateway with a 1.5m long 15 dB gain omni whip antenna mounted on the roof of my 3 floor house which is on top of the highest hill in the area. My FiPy with supplied aerials works within about 2m of the antenna, at 5m I start to have real problems (outdoor line of sight). My other LoRa devices work at up to 200 m line-of-sight but after that even with line-of-site I get nothing.

    I would say practical LoRa range with a good 15 dB gain anntenna on the gateway is about 50 m. Not quite the 30 km we were promised :-(

  • @chrpal Note that a 15 dBi omnidirectional antenna has a very narrow beam vertically, so you should make sure the antenna is really vertical, and that the other node is placed in the horizontal plane centered on the antenna (the antenna manufacturer should be able to provide radiation patterns for that antenna which will give you a much more precise idea).

    Also, in a forest, you’ll quickly loose LOS. Radiowaves like LOS. I would recommend you start in open terrain before moving to obstructed terrain.

    Also remember that beyond the direct LOS, you should have clearance in the Fresnel zone. Even at 250m, the Fresnel zone extends up to 4 meters around the LOS (at the midpoint). The higher one or both antennas are, the better.

  • Hi guys, your answers are quite interesting as I face the same problem like @maqbool .
    So to get things more clarified, could you provide a little bit more information about your concrete setup?

    1. Which frequency band (or concrete frequency) are you using / in which country you tested your setup?
    2. What were the configuraiton parameter? I read about SF12BW125, what coding rate you had?
    3. At which height you placed your GW or receiver? Under which circumstances you made the transmission (LOS or NLOS, density of urban / forest environment)?
    4. What kind of equipment is necessary to have a professional base station?
    5. Which GW and LoRa nodes you used (RPi Shield, Dragino, Seeeduino, Libelium etc.)?
    6. What kind of antennas and how much gain?
    7. Which kind of connector (pigtail or SMA connector directly soldered on PCB)?

    I first tested LoRa to LoRa communication between two fipy nodes. I used a 30cm pigtail cable which
    was connected to a 868Mhz fiber glass antenna (https://www.airbatt.de/AIRBATT-OGN-Hochleistungsantenne-868-MHz-15dBi-Gewinn-N-Anschluss). Furthermore, I tried to make transmission tests with varying parameter (frequency, bandwith, coding rate and spreading factor) within a medium dense forest. Both boards were at a height of ~1m and my max distance was 250m at a RSSI of ~-113 or somewhat.

    If you could provide some more technical details this would help to see differences and understand, what me and @maqbool are maybe doing wrong.

    Best regards and also thanks for the answers so far

  • @maqbool said in What is the realistic range of LoRaWAN?:

    Yes, I also considered that. I am using SF12BW125, with which I have got the 250m results

    Well with SF12BW15 i can achieve 12km in non urban environnement and 3 km in urban environnement with a car on the first floor in underground parking (atenna on the roof of building)

  • @maqbool In the past I've had a gateway based on a raspberry pi with a 6dB omni cover 30 miles line of sight without breaking a sweat, and the current RAK gateways that we deploy will easily do 5 miles depending on terrain and that's in both Wales here in the UK and in Australia.

    I've written up a few reviews of various gateways at https://www.mockingbirdconsulting.co.uk/blog/ and I'll be adding the PyGate to that list soon as mine arrived this morning, but I'd suggest that if you're not that far from your external antenna, and you're still getting poor results, either place the gateway above roof height if possible or look at potentially getting another gateway such as the RAK7258 Indoor Gateway.

  • @maqbool Another note about the Pycom antennas: I made a refection test with two samples I had, when I had by chance access to suitable equipment. They showed the lowest reflections between 950 and 1100 MHz, with a reflection factor of ~0.5 at 868 MHz. The transmission was best between 840 and 980 MHz, although this test had no precise set-up (just two antennas in an ordinary room).

  • @maqbool The Pycom antenna is a Wavelength/2 model. So it should work without a ground plane. I used that too for my tests. But I had it all assembled into a metal box, which I placed onto the roof of my car. The box prevents stress from the pigtail cable and the connector. A broken/poor connection to the antenna may also be the reason for bad results. Even if that is broken, you will have some communication due to the high sensitivity of the LoRa method. The car may have been served as an additional ground plane.

  • @jcaron Yes, I also considered that. I am using SF12BW125, with which I have got the 250m results. Do you suggest any other parameters I should take care of, that can impact the transmission range?

  • @robert-hh I use the antenna supplied by Pycom. Does that need a suitable ground plane setup? Although yes, I just walked around with the FiPy device in my hand, so the antenna was "hanging loose" as you say. I will see if fixing this gives me better results.

  • @jcaron It's not the physical sensitivity of the receiver, which changes. It's the way the data is coded, which at slower coding allows to detect it in the background noise. Like each piece of information is transferred for a longer time with a well structured signal which is different to a random noise.
    The interesting aspect of Lora is, that the signal level can be substantially lower than the noise level, which seems -112dB for the SX1272 chip, but I see messages coming in with an rssi of < -124dB (at least what's reported).

  • @maqbool in addition to TX power there’s also the SF/data rate. The slower the data rate (higher number SF, like SF12), the longer the range is supposed to be, as the receiver is supposed to have better sensitivity and thus accept weaker signals. YMMV, though.

  • @maqbool For my gateway I use a) Aurel GP antenna, a simple low gain ground plane antenna , mounted on the roof of our house. b) a home-built ground plane antenna trimmed to the proper frequency, placed inside behind a high locate window.
    For the nodes I use either the antenna supplied by Pycom or a genuine wavelength/4 antenna. The latter must be placed on a suitable ground plane. I use the sufficiently large metal box with the Pycom module inside. Not a perfect ground plane, but better that just let the antenna hang loose at the board.
    And you have to take care for the polarization. The antennas must stick upright.

  • Thanks for the replies guys. I've tried placing the gateway indoors and outdoors (5-7m height), and achieved the same poor 250m results. Although, my setup wasn't in direct line of sight. Do you have any recommendations for gateways and antennas, that you used in your projects that gave you 2-3 km range? From my understanding, the only parameter to control the transmission/reception quality was the TxPower parameter..., but it seems antenna selection play quite a role.

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