Using WirelessMon to understand dropouts

[jaypeecee]

Hi Folks,

This is my first posting on this forum. I have been a user of WirelessMon for some time now. I'm currently getting a lot of WiFi signal dropouts but it's unlikely that this is being caused by other networks in the neighbourhood. Most of the other networks are on Ch 11, one is on Ch 1 and I'm on Ch 6. There is one network on Ch 7 but its signal strength is usually below -70dBm as shown on the WirelessMon graph. My current network card indicates typically -50dBm (graph) when connected to my router.

So, there appears to be two options. The dropouts that I'm getting are not being caused by other networks but other sources of 2.4GHz. Unfortunately, I don't have the luxury of proving this using something like Wi-Spy. The other option is that my received signal strength of -50dBm is too low to ensure a reliable wireless connection. Out of interest, what sort of figures do other users of WirelessMon see for received signal strength and may I ask what combination of router and network card you're using? I'm using a BT Voyager 2091 and Belkin F5D6001.

All comments would be appreciated.

JPC

[Tim (PassMark)]

-50dBm isn't a fantastic signal but really it depends on the sensitivity of the card, eg a netgear USB WG111 here a foot away from an access point (DLINK DIR-635) is reporting -45 dBm, where an Intel 2200BG is reporting -20dBm.

A likely cause of other wireless interference would be cordless phones running on the 2.4GHz band, so if you have any of them around you could try turning them off and seeing if it improves your connection.

[jaypeecee]

Very interesting

Thanks, Tim

Your point is well taken and makes a lot of sense. I wonder if anyone has ever published a list of network card sensitivities. It's amazing that the two cards you have quoted have sensitivities that differ by as much as 25dBm. I suppose I could get in touch with Belkin to see if they have a figure for the F5D6001 sensitivity. Here goes...

Regards,

JPC

[jaypeecee]

More thoughts!

Tim,

Correct me if I'm wrong but the two cards that you have quoted are not strictly showing different sensitivity but different output from the RF section of each card. Isn't that what WirelessMon displays?

So, in order to reduce wireless dropouts, it seems to me that one has to increase signal to noise ratio; by 'signal', I mean that which is received from one's own router. 'Noise' is that which is received from other routers + stuff from cordless 'phones, etc. In order to increase S/N ratio, it is presumably necessary to increase the margin between the received signal from one's own router (in my case -50dBm) and that from any other router that is within 5 channels of your own channel. If it's more than 5 channels away, then there is no frequency overlap. The question then is - what margin is required? It will vary from setup to setup but do you have a feel for what would be desirable?

One last question - can WirelessMon display the received signal strength from network card back to the router?

Thanks.

JPC

[Tim (PassMark)]

It is the RSSI (http://en.wikipedia.org/wiki/RSSI) as reported by the cards, sometimes reported as a dBm values and sometimes as an integer value representing different levels of power. A perceived "Good" value for particular cards is beyond my level of knowledge but the best level would be the one where you don't have frequent dropouts

There's a Microsoft guide on improving Wireless strengths here, http://www.microsoft.com/athome/more...elesstips.mspx, which is mostly "upgrade xxx" but has a few good points like the positioning of the access point.

How far away is your access point from the card? If it has to travel through walls and other objects that will certainly affect it, especially bodies of water like water heaters.

I think your network card is able to connect to an antenna as well, that may be an option worth exploring. It may also be time (and i hate to take the Microsoft line) to upgrade to an 802.11g card, as apart from increased transfer speeds 802.11g handles decreased and reflected signals better than 802.11b.

[jaypeecee]

Thanks

Tim...thanks for all the info. As for the last question I posed, "Can WirelessMon display the received signal strength from network card back to the router"? I can't see how it can but thought I'd ask the question.

To all other users of WirelessMon...going back to my original post, "Out of interest, what sort of figures do other users of WirelessMon see for received signal strength (RSSI) from their own router and may I ask what combination of router and network card you're using? I'm using a BT Voyager 2091 and Belkin F5D6001".

Thanks,

JPC

[Tim (PassMark)]

There isn't a way (known to use) of retrieving the strength of the network card as it appears to the router.