DAS and LoRaWAN


(Redwirelessus) #1

Looked on all topics and couldn’t find any threads pertaining to Distributed Antenna Systems (in building distributed wireless) and LoRaWAN. Has anyone attempted/experienced with this? Instead of a cellular BTS, small cell or repeater, what about a LoRa gateway output into a DAS In Building system? Any constrains? Thoughts? I will be attending MWCA LAX in a week and will chat with some DAS folks to talk about this topic. Thanks, j


#2

The range of LoRaWAN is much bigger then wifi… so even for a large structure (like a stadion) a single antenna and gateway will be sufficient to cover the whole area.


(Redwirelessus) #3

Actually, this is not true. 1) Range is one thing, but penetration is another. Even with such low sensitivity such as -130 to -140 dBm, negative SNR and huge range, you can’t guarantee always LoRaWAN penetration, say on tunnels, basements (yes, even on a stadium), low e-glass covered hotels, etc. In my experience, even high rise buildings in Chicago low e-glass coating can attenuate 40-60 dB! Today Semtech and 2 LoRaWAN operators (Senet in the US and Tecklect in Canada) were talking on a webinar panel and clearly all agreed that although LoRa’s range and SNR are extremely robust, it will not cover everywhere all the time - especially indoors. 2) I’m not referring to WiFi, as WiFi is not, by its 802.11 nature, a distributed medium (Access Points are autonomous and, thus, can’t be distributed with a DAS). I’m talking about Cellular DAS - the same one used on, for example, in a stadium to extend cellular signal. 3) I already tested a 1 w Cisco LoRa gateway indoors and it only covered half of a ~366 sq m building in the downlink and less than that in the uplink because, of course, the sensors had less power. 4) The question is not whether LoRaWAN is capable (or not) to cover ‘a whole area’ from the outside but whether anyone has experience, instead of adding additional gateways to an in building system like my Cisco example, connecting a Gateway to a DAS system. Hope this clears out the confusion :slight_smile:


(Nestor Ayuso) #4

By nature, LoRaWAN is a distributed antenna system. you can deploy as much gateways you want, no worry about overlapping each other. All the gateways act as a cooperative receiver system, all listening in the same frequencies. The network server manages all the gateways: de-duplicates duplicated uplink frames and chooses the right gateway to use for downlinks.

For outdoor high towers you can use high capacity, macro gateways, even with three sectorial antennas. For indoor you can use cheap micro gateways.


(Redwirelessus) #5

Thank you. Again, that is not the question. I know how LoRaWAN works. I just want to know if anyone has plugged in a LoRaWAN gateway as a signal source onto a Fiber DAS system such as Solid, JMA, ADRF, Commscope, Corning, etc. Thanks, j


(Jac Kersing) #6

As you are the first to bring up this subject chances are near zero anyone has done this. If you are going to, please keep us informed.

Just for my information, what are the cost of such a Fiber DAS system? Does it make economical sense to use it when gateways can be bought at $270 (qty 1, at higher quantities pricing will drop)?


(Remko) #7

Hi,

A DAS is a distribution system for radio signals trough big buildings like hospitals shopping malls airports and metro networks. It connects a single base station to multiple small antennas covering the entire system. At the same time it can serve multiple radio networks.

As any RF system like GSM LTE TETRA or Analor PMR radio can use a DAS I expect that Lora can use it too.
Due to the narrowband character of the signal I expect no problems with transport trough the DAS.
As of the positive linkbudget of LoRa i do expect a gateway to be able to receive a direct signal from some nodes and the same signal trough the DAS. LoRaWAN can handle this situation with no problem.

You may send me a DM for further discussion on this topic.

Cu Remko


(Remko) #8

There is a strong urgency at for example airports to have control over all installations on site.
Same count for hospitals.
A DAS is a mandatory service from the landlord to operators in such cases.


(Redwirelessus) #9

@kersing Kersing, thank you. I will definitely let you guys know. Typical DAS systems’ prices vary depending, of course, on SQ FT/M, whether is repeated, autonomous signal sourced, neutral hosted (meaning it can serve multiple wireless service operators in one same system), fiber (active) or passive… but usually will be spending between $20k to $100k or more, again, dependent on the size and scope.

Why DAS? As @pe1mew explained, there are many instances where there are already DAS systems established within a building, such as a Stadium, Hospital etc. Let’s assume you have a 40 story building that already has a fiber DAS system for cellular and public safety through a central fiber backhaul - now you come in and explain that although the building is within coverage of the LoRaWAN network from the outside ,survey/tests shows it can’t get to the center elevator shafts, basements and/or other parts of the interior of the building due to the nature of the building construction materials, signal loss, etc. Now you propose you’ll install various gateways (since I don’t think one will cover the whole building) for LoRa, you’ll have to install new cables, new internet backhaul points, etc. This is a very fancy building and they already went through the ‘tear of celing/walls’ for this with the DAS. Guess what the answer to such demand will be?

This is all too common, so I’m already in discussion with some DAS folks (especially ADRF who I’ll be meeting in MWCA in Los Angeles in a couple of weeks) to see if, instead, we can plug a high capacity gateway to the DAS ‘headend’ (the part of the DAS where it accepts all RF/wireless technology inputs) and also ‘distribute’ that signal ‘actively’ all throughout the building. This not only cuts costs, but also time, opex, capex, etc. It is in these particular circumstances where this application would seem logical. But I’ve never tried it so, as long as the DAS equipment, antennas, cables, connectors, etc is capable of ‘handling’ the ISM/LoRa frequencies and technology, I don’t see why not. I’ll keep you all in the loop as I find out more! Thanks! j


(Redwirelessus) #10

I wanted to very briefly add the latest : I was able to have a chat at Mobile World Congress Americas last month with, both, DAS manufacturers and LoRaWAN entities about ‘converging’ or testing LoRa GW’s and Sensors as RF Signal Sources for In Building DAS systems. We’re all of the opinion that we can’t see ‘why not’ it wouldn’t work. The most important part is that, as with any in building DAS (Distributed Antenna Systems) the ‘head end’ or the ‘input unit’ sort of speak has to be able to ‘accept’ the frequency and technology (for example, there’s a card for 800 cellular CDMA, another for 700 cellular LTE, etc), so there would have to be a ‘card’ for (in the case of US) 902-928 MHz ‘LoRa’… no one, that we know of at this point, has that in the market. I’m currently having that discussion with at least 1 DAS mfr and 1 LoRa mfr to see if we can have a POC (Proof of Concept). This might take a while but FYI I’m on it and will continue to update accordingly. :slight_smile: