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Single Access point with isolated External Antenna's

Hi, 

So I have a suite of rooms which for simplicity is a 10 X 10 meter main room with two 5 X 5 rooms bolted on one end (rectangle with the top third walled off and then sub divided in to two. The room structure is poured concrete with double rebar steel reinforcement and steel doors. Which means each room is isolated from each other as far as wireless signal is concerned. 

This lay out of suites is then repeated through out the building around 30 times. Each Suite will be manned by 1 or possible 2 people so at any one time only 1 of the rooms with in a suite is likely to have staff in it. 

Now the simple method would be to put a access point in to each room with in a suite, but due to the nature of the building this is not possible, and also extremely costly (no due to access point costs but costs associated with fitting them to the rooms). 

 

My question is if you took a single access point and connected 3 external antennas to it, placing on in each of the rooms with in a suite, what would happen and would it work. 

I can see 2 main issues 

1. Hidden nodes, causing collisions and poor performance, but this is not a show stopper as with only one or two devices in use in a suite an access point would only be dealing with low numbers of users and there are technologies to over come some of these issues. 

2. you loses MIMO and would fall back to SISO operation, which would reduce throughput performance. 

 

However given we are looking at supporting 1 or 2 low BW users per AP, the question is not is it a good or bad idea to do. But would it work and if so what are the issues we would face.  

 

 

2 REPLIES
Hall of Fame Super Gold

Here's the thing ... if you

Here's the thing ... if you do what you plan to do and you ran CABLE and stick a low-powered antenna into each room ... it still won't work.  The cable loss would be spectacular.  The signal strength will be low.

Hall of Fame Super Silver

Just to add... You need to

Just to add... You need to also understand what diversity is and how it works in conjunction with the access point.  When using multiple ports in a given access point on the same radio band, the access point uses diversity to determine which antenna has received the best signal from the client at a given time and uses that to send the data back. MIMO and the number if spatial streams also helps when the ap revived and transmits data. The key here is keeping the antennas separated but not more than three wavelengths apart. So if you measure the distance between the antenna ports, go 3 times that and that should be your max. 

In your scenario, if you want coverage in rooms, you should survey and see if you do need an access point in each room or not.  In the end, you need to spend the money if the requirement is to provide wireless in each room to cable and mount access points to these rooms.  There is no other way around this. 

Scott

-Scott
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