Wireless coverage

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AllNightNerding

411 posts

Ultimate Geek

#26270 16-Sep-2008 20:57

Im currently doing an installation at a business, they have an office that has the wireless router in it, and about 70m away with minimil stuff in between is a house that has a laptop in it.

What would be the best way to do this? would wireless N cut it or would wireless G with a bigger aerial be a good option?

Its out in the middle of no where, so security and all that isnt the bigest concern.

They are getting hooked up with Xnet tomorrow night.

-- Divett Enterprises -- The Power Of Tomorrow --

itxtme

2102 posts

Uber Geek

#164937 16-Sep-2008 21:14

you could always get one of these -> http://compnetworking.about.com/od/wireless/ss/wirelessgear_7.htm

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cyril7

9050 posts

Uber Geek

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#165007 17-Sep-2008 08:46

70m of cat5e is ummmmm, about $30 and will give you 100% performance 100% of the time (assuming you dont kink it all up), ideally you should not use standard PVC sheathed cat5 outdoors, but if carefully installed down say a fence line so that it does not sit in water or in conduit down a fence line, or if you are a real cheapskate use black garden irrigation hose as a conduit.

As for radio options, 70m is not too far, but if you just want an AP that can direct adequate power toward the laptop that will directly connect to that AP in the office, then something like this will do just fine, can be mounted outdoors on the roof eave or side of house up high to clear obstructions (ie cars etc) using a hockey stick that you would normally mount a UHF TV antenna on, comes with POE coupler, has 10dBi gain which will throw plenty of power 70m or more (much more). You would spend a hell of a lot more money cobbling together any other solution with more domestic kit and external antennas.

Oh, and even though the above link does not state it the nano stations can be opertaed in a multitude of modes, including AP, client bridge, repeter, WDS etc, the firmware is very very flixible

Cyril

iainw

75 posts

Master Geek

#165055 17-Sep-2008 11:45

Depends entirely on how much you want to spend. Cyril's suggestions are probably one of the cheaper ways of setting up a reasonable solution.

802.11n won't be of much help - the laptop is unlikely to have an 802.11n client, and there is not much multipath in an outdoor environment anyway.

Antenna's are better than amp's, as an amp doesn't have any impact on the signal being recieved from the laptop.

AllNightNerding

411 posts

Ultimate Geek

#165107 17-Sep-2008 16:36

that nano station does look like the best option.

The reason why cat isnt an option is because the ground would have to be dug up, along with concrete.

ill see how they go with the n1 station and the g laptop, and if that doesnt work then I will get them to take that back and get a decent system put in.

-- Divett Enterprises -- The Power Of Tomorrow --

AllNightNerding

411 posts

Ultimate Geek

#165120 17-Sep-2008 17:29

So I think now I will go with:

Getting a Netgear DG834G

Few questions on the antennas:

The nanostation one, from what I have read about that, you plug into it an ethernet cable, and a power cable and basically it acts as a wireless access point.

With antennas, do most of them just plug into the aerial port on the modem/router/wirelss acccess point, and is there any variance in the plugs, so can any brand go with any brand?

obviously I will be getting a 2.4ghz, but how many db should it have?

the nano station as 10 so somthing around there?

and sorry for the double post :D

-- Divett Enterprises -- The Power Of Tomorrow --

iainw

75 posts

Master Geek

#165263 18-Sep-2008 08:57

RF mathematics is relatively simple.

Radio waves at 2.4GHz will attenuate by -84.6dBi over 70m. You will want to add a fade margin allowance for rain/slight mis-alignments in polarisation, interference etc. Personally I add -15dBi to be nice and safe.

You will need to know what your transmit power of the two radios is, for your calculations, use the lowest power - your radio strength only affects sent radio waves, not recieved radio waves. Since RF is a two way medium, always use the lowest power.

Take this transmit power, it will most likely be something like 14dBm (25mW).

14dBm + 10dBi for the nanostation antenna - 84.6dBi FSPL - 15dBi Fade Margin = -75.6

The spec sheets for the nanostation will give you the details for the RSSI (Recieved Signal Strength Indicator) thresholds. As an example, a Motorola AP5131 will give you 36MBps throughput at -75.6dBi. Lets say your nanostation has a 54MBps RSSI of -74dBm. This means that to get 54MBps of throughput, you need an antenna that is at least 1.6dBi.

In a nutshell, it all depends on the specs for your AP's and how much throughput you need. Bear in mind, that 54MBps throughput will actually only give you somewhere around 30MBps of traffic. Do the same calculation in both directions, and use the biggest number - ie if one direction tells you the antenna needs to be 5dBi, and the other says 7dBi - use 7.

The only things that will change, are the pair of radio transmit strength and RSSI threshold.