Wireless Networks Thread, wireless / physics question in Technical; Our buildings are in residential areas, and are seperated by houses and other buildings. We cant link them with fiber ...
24th September 2008, 04:38 PM #1
wireless / physics question
Our buildings are in residential areas, and are seperated by houses and other buildings. We cant link them with fiber as its too expensive to dig up the public roads. So we use wireless directional antenna on the roofs with netgear bridges. (802.11g)
From building A to B it works absolutely perfectly, and normal network usage it is almost impossible to tell that your not plugged in.
But from building B to C, even though the signal strength is reported in the AP, packet loss is astranomical.
The only thing different is that between B and C it goes over treetops and roofs whereas A - B is pretty clear.
Am I correct in thinking the wavelength on 2.4Ghz is about 12.5cm? So should the trees and rooftops be having an effect?
Its so unusable accross at building C its not funny.
24th September 2008, 04:44 PM #2
Do you have anything else local operating on the same channel?
24th September 2008, 04:51 PM #3
What i would suggest also. Ideally you would have 4 wireless stations creating 2 bridges.
Originally Posted by FN-GM
A Wireless to B on Channel x
B wired to C
C Wireless to D on Channel y
24th September 2008, 05:17 PM #4
Trees are awful for wireless as like people they are full of water, 2.4ghz is a microwave frequency which is closely coupled to water and so lovely green leaves act as an impressively effective cone of silence for wireless traffic as the signals are absorbed rather than bounced. I suspect you may need to try and route the signal around the obsticals differently or use a more focused antenna that can be targeted directly at the receiver.
Your other options would be to try using 802.11a ad it 5.something ghz band may be more resilient to both the obsticals and any electronic interference in the way or to use 802.11n with dual or tripil antennas on each side that can use multiple path and a wider frequency band to transfer the data.
24th September 2008, 05:20 PM #5
Yup thats the excact setup. There are 2 AP's on building B, one at the front linking to A and one round the back on the side linking to C.
Originally Posted by Psymon
Ive been through every channel on the B-C link to see if it makes a difference.
We have a company coming tomorrow to demonstrate WiMax or something along those lines, but 11a and 11n is two of the other options I have been thinking along.
24th September 2008, 05:35 PM #6
Check these websites out:
What is the best WiFi antenna for me? | Do-It-Yourself Wireless Antennas Update
Wireless - Technical Discussion Document
Yup, anything that retains water is going to affect wi-fi signal. 5GHz band is much better, but will still suffer some degradation, and if you are going to use it, will have to be registered with Ofcom (for a small fee) as the military and emergency services also use the same band.
I would recommend directional antennas, mounted on poles to have a clear line-of-sight, or you trim the trees back a little.
24th September 2008, 06:29 PM #7
YouTube - Heineken - Road works
Have you waited for something like to happen?
24th September 2008, 06:50 PM #8
why not ask a wireless specialist company for a survey...?
Might be able to swing a freebie - there might be things you haven't considered....
24th September 2008, 08:06 PM #9
Laser costs about £3k - £5k, but this will start at 100mbps, you do need line-of-site.
We have a 11mbit directional wireless, and found we had to trim a few trees to get the signal through, and if it really buckets it down, to the extent we can't see the building, neither can then wireless...
I have been trying to get our SLT to approve replacing the wireless with something the kids don't aim footballs at, and fibre is the best option (for us), it's just not cheap.
Other options I considered:
a) an additional phone line with SDSL, that we could get a VPN through - but no SDSL in the area (apparently).
b) pay the LA, who provide our Internet access, to link to it (at 8mbit), and let us have a straight VPN through - but they said no chance.
c) fibre across the road - no-one was able to get me a price on a mole...
Contact a local network cabling company to see what they can do, ask for a survey.
24th September 2008, 08:11 PM #10
If you don't believe there's no SDSL provision given the apparently, check for yourself at Samknows.com.
but no SDSL in the area (apparently).
24th September 2008, 08:12 PM #11
side tracking a bit but how do you create a wireless bridge ( presuming this is between 2 wireless access points ) or how do you do it exactly ?
Originally Posted by Psymon
24th September 2008, 08:25 PM #12
Samknows.com tells me there is SDSL service.
Originally Posted by kmount
But when I talk to actual phone companies, Redstone, BT, they can't tel me who... I suspect samknows.com knows about the LA connection, but this is somehow reserved by them, and not available to anybody else. Which is why I went to the LA and asks them about another connection, and they said no.
24th September 2008, 08:32 PM #13
Without being facetious is your LA connection SDSL?
24th September 2008, 10:41 PM #14
BT have services which allow you to link buildings together, enquire with them, they can do them for you for a price, Kilostream I think was one going back years ago that was popular for linking remote offices back to central ones, but it will no doubt have been superceded by now. They were all about direct P2P links though which would do the job you need.
24th September 2008, 11:08 PM #15
Try pointing B and C antennas slightly to the side or above the trees; or both towards any other high buildings in line of sight of both sites - it might just bounce
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