I have been doing some research with regards to smart buildings, specifically high rise residential buildings.
We are offering leak sensors to our high rise residential clientele and from what I gather, it seems to be somewhat of a trial or error scenario.
My Question: In a high rise building, how many gateways should I have? And where should they been placed in order to cover the whole building?
Some people have said on a 25 story building, one gateway on the roof will cover the whole building. Others have said to install a gateway every 3 floors to be safe, however this can get pretty expensive, especially the fact that the only options seems to be LTE.
Do I place then In the stairwell? Or in the electrical closet of each hallway?
I am hoping to hear some case studies or anyone who is familiar with this type of installation.
There is no prescriptive solution as each tower block and local conditions may vary… get out there and test deploy to see what works!
From my own tests and deployment experience I find it can be a compromise based on objectives. E.g testing on a 16 story residential block I found gw ant placed around mid point was fine (testing at front door of each unit as not able to get access) with coverage in the communal areas, stair well and even inside the lifts was viable. In the end decided to place nearer the top (2/3rd of way up) was a good compromise as still got ok coverage at lower level but had advantage that the gw also then provided decent coverage for several ‘oom even km’s In surrounding area such that it allowed community coverage for other tasks (car park monitoring, local river flood levels, asset/staff tracking etc.). It was noted that some lower nodes were at much higher SF’s implying potentially shorter battery life once deployed. I note from your other posts that you’re looking at small water leak detectors…small batteries…so this may be a concern. Problem easily solved by split deployment with 2 gateways densifying the deployment… one at 1/3rd and one at 2/3rds building height? Remember also that esp high gain ants typically have a vertical null directly above/below which can affect reception. If using 2 GW’s have them laterally offset relative to each other and that will ensure their nulls don’t align
The other factor to consider is that these tower blocks are often built in clusters/campus style with 2, 3, 4, 5, or more built adjacent to each other and if you put GW’s in each one they provide mutual support & back-up with side signal often stronger than vertical penetration. Good for e.g. fire cover where damage or fire service shutting down power may take out gw(s) in a given block!
Drywall and concrete are going to be the major obstacles in the building we deal with. The older building are plaster walls, wood and metal beams. They may be more challenging.
Where did you place the gateway? Was it in the middle of the building? In a corridor? or towards one side?
Lets say its a current building (cheaper, thinner material)
I am thinking the best placement for gateways will be in the electrical closets since there us power and can be locked. They are in the same place in each floor usually (due to wire conduits) So this may be more difficult to put them laterally offset relative to each other.
The alternative is to get an electrician to bring power to the stairwells and begin at a lower floor then go every 5 floors up and put one in the stairwell on the opposite side of the hallway. This may be overkill but at least ensures coverage?
The disadvantage of electrical closets is loads of wiring which will interfere with the antenna patterns and as a result with the radio signal. Keep at least half a foot (or about 16cm) between the antenna and any wiring (except below the bottom of the antenna) and keep it well away from large metal structures as those will shield the signal to that side.
Also such closets seem to act as local hubs/concentrators for RF noise - either mains borne or through local RF control(ed) devices that are often placed there or near by for the same reasons you were considering Raising the RF noise floor seen by the GW and reducing SNR - Recommend you stay atleast 2-3m away from these…
Hi @Gianpaul, please remember that the gateway has two main parts; the powered electronics and the 915MHz LoRaWAN antenna. I recommend that you put the powered electronics in the electrical closets for convenience, maintenance, etc. I recommend that you then use an appropriate co-ax cable up to 30ft in length and mount the LoRaWAN antenna well away from the electrical closet and any main risers. This also allows you to place the LoRaWAN antennae at different horizontal offsets on different levels; e.g. 30ft north of closet on level 2, 30ft south on level 5, etc.
Branded to the extent of being gold-plated from a corporate supplier. There’s nothing quite like rending a $200 RF device almost stone deaf by skimping on the cable & connectors. To that end, even the low cost Vector Network Analyser are worth buying just to check things.
It’s good to see all these gentlemen recommending coming out the closet …
repeating the obvious, it s hard to generalize this, as it really depends on the specific building, materials, layout etc etc (we re covering a massive 5 store steel/concrete building fine with just one gateway on the roof - almost surprisingly) -
i wanted to underline what @Jeff-UK hinted at: often buildings are
and in general, the best way into dense buildings is often from outside.
so, if you can negotiate access to and stable conditions in a neighbour building, that s worth checking out.
Raising the RF noise floor seen by the GW and reducing SNR - Recommend you stay atleast 2-3m away from these…