TechSpot

Is client-side-only wireless gain not enough?

By Rick
Mar 25, 2008
  1. ** Edited this to simplify it.

    I recently deployed a sketchy 802.11b/g wifi network using some equipment a customer had purchased. (2 Apple Airport Expresses in wireless distribution mode) There was a lot of obstruction over a large distance and it would basically not work in the target area, although there was a faint signal. The distance is about ~120ft, through several rooms and out into the garage. I recently went back to iron it out.

    I installed a 200mw USB adapter (Atheros AR5005) with a +8db gain omni antenna on the client computer. The increased signal strength was dramatic; however, I was still unable to fully connect. The wireless itself would establish a connection, but there was no communication with the router, as evident by the inability to lease a DHCP address, access web admin or surf the net. The wireless network works fine if we move the computer closer to the last airport (I can verify the last airport in the WDS chain has connectivity).

    Despite getting a great link, it seems like the router and the client computer are not communicating at the distance my client wants. The network is detectable by the 'regular' wireless card, but it is hovering around 0-1 bars and stays pretty much unconnectable. With the new USB adapter and antenna, it is 3-4 bars and connects with little issue.

    I also tried a 500mw USB wireless adapter with a +8db antenna with simliar results (RTL8187 chip).

    So, the question is, why doesn't a high powered wifi card and big antenna work? Does it just improve receive but not send transmissions? If so, what's the point of higher gain antennas/devices and how do I solve it... would a bigger antenna on the router be the solution?


    Here's a VERY rough diagram of the layout.
    Code:
     =========================================
    ||MODEM||###||###||#####||####||####||###||
    ||##{AP}|###||###{AP}###||####||####|####||         ==========
    ||#####||###||###||#####||####||####||###||        |GARAGE
    ||#####||###||###||#####||####||####||###||        |CLIENT
     =========================================         |  
    
    *The last three rooms are off limits as they are another person's apartment.
    
    
     
  2. jobeard

    jobeard TS Ambassador Posts: 9,342   +622

    with 3-4 bars of signal strength you should get a connection (at least w/o encryption!)

    Have you tried Network Stumbler? It measure Signal strength and signal-to-noise ratios.
     
  3. tipstir

    tipstir TS Ambassador Posts: 2,393   +107

    www.passmark.com wireless mon one of the better wireless monitor programs under windows, but anyway 4 bars is great...
     
  4. Nodsu

    Nodsu TS Rookie Posts: 5,837   +6

    Those monitors give you the signal you are receiving. There will be no information about the signal that the access point is getting from you and that was the question.

    You could get another client and use that to monitor the signal coming from the garage at the location of the second AP.

    It should work with only one directional antenna, although with two the results would be better.

    I'm thinking that maybe the two APs are interfering with each other because they appear to be on the same line for the client in the garage.
     
  5. tipstir

    tipstir TS Ambassador Posts: 2,393   +107

    Wireless Mon does allow you to test the signal from the WAP but you need to connect to the WAP through it using that option. Now I run two WAPs each are on their own channel. The biggest mistake a lot of users make is that they set them to auto channel select. Nope don't it. You manually set the channel you want to use. If laptops are on the first floor and you have AP #1 on the first floor set to channel 1 then the laptops should be using the same channel. I set them to that channel through the WNIC. Signal streight is Excellent and Excellent for the second floor. Range for wireless is good up and bottom and 360 degree ratio for me here. Very good shows up if I go into the woods past the garage.
     
  6. Rick

    Rick TechSpot Staff Topic Starter Posts: 4,573   +65

    Thank you for the input.

    WirelessMon looks like a good utility. Netstumbler has been my choice in the past, but it does not work with Vista (which is what I and my client have to work with). Its a shame development has been so slow in the past few years.

    Hopefully I will have the opportunity to take some meaningful benchmarks and post some more info. Here are some more details that might be of interest until then...

    • I manually assigned the channel to what looked like the 'least used' channel space. I tried a number of channels - none really appeared to provide different results. The complex is littered with wireless networks though (About 8 others within 200ft or so), so I'm absolutely certain there is a considerable amount of interference.
    • I've been keeping WPA encryption disabled while working on it - just to rule it out.

    If I were to use something very directional - like a cantenna - do you think that would work? Right now I'm getting a pretty consistent and good signal, but I still can't resolve any websites or even an IP. It makes me wonder if a powerful antenna and wifi card on the client is just part of the equation. Maybe I just need something with more focus? :)
     
Topic Status:
Not open for further replies.

Similar Topics

Add New Comment

You need to be a member to leave a comment. Join thousands of tech enthusiasts and participate.
TechSpot Account You may also...