| In this article we will look at how to tackle
some common wireless network problems that people come across. This
document will outline the steps you should take if you encounter one of
the mentioned issues. |
Check the wires and wireless network adapter
Checking that all your wires are plugged in at the router and from the plug
is one of the first things you should do – provided of course that you have
access to them. Verify that the power cord is connected and that all the
lights of the router and cable/DSL modem are on. This may seem like a
ridiculous suggestion but you should never disregard the obvious. You’d be
surprised at how your configuration can be perfect, and after a while of
playing around with settings you realize that the network cable leading from
the router to the cable modem has come undone slightly.
You will also want to check that your wireless network adapter is switched
on. Some laptops come with a small blue or red button on the side while others
require you to enable it from the operating system. In Windows, go to device
manager and check that your wireless network adapter is enabled. If you have a
PCMCIA or USB wireless adapter try removing it and then re-inserting it while
Windows is running so it will re-detect it. The lights on the adapter give an
indication of whether there is a problem. On mine, I have two lights; one is
orange to signify that the PCMCIA card has power and the other is green to
show if a connection has been established. A blinking green light means that I
am not in range of a wireless access point or there is a problem with
connectivity, whereas a stable light means a connection has been established
successfully. Take a look at your device documentation as these sorts of
details will vary with each product.
Driver Compatibility
It is important to make sure that you have installed the correct device
driver for your wireless network adapter. This can cause all sorts of problems
or your adapter not to function at all. A friend of mine recently set up his
own wireless network at home but complained to me that his wireless network
connection was going “crazy”. Upon inspection I realized that he had
configured his router properly but installed the 5v instead of the 3v driver
on his laptop PCMCIA network card. Once the correct driver was installed,
everything began to run smoothly. It just goes to show how even the smallest
detail can make all the difference so make sure you have the correct driver
installed!
Low Signal Strength
There are a number of factors that can cause the signal of your access
point to deteriorate and the performance of your network to fall under par.
Practically any appliance that operates on the same frequency level (2.4 GHz)
as 802.11b or 802.11g can cause interference with your wireless network. Be
sure to keep cordless phones, microwaves and other electrical equipment at
least 1m away from the access point. Try changing channels on the access
point and test it out on one of the clients. To change the radio channel on
the access point login to the configuration (usually a web based interface)
and go to the Wireless Settings (will vary depending on vendor) section,
select a different channel and save settings. On the client, go to Device
Manager, right click your wireless network adapter and go to Properties. In
the advanced tab select the Channel Property and change the Value to the same
number as the one you chose on the Access Point. Disable and then re-enable
the wireless connection.
Access Point Location
You may also want to try changing the position of your access point antenna
to improve performance. Play around with its position and see if you notice a
difference. I find that if I point the antenna sideways or downwards I have
better reception on the floor below. The following images demonstrate what I
mean.
Antenna pointing upwards (default)
Antenna pointing sideways
The location of your access point is vital. Try and place it in a central
location, as much as possible avoiding physical obstructions and reflective
surfaces. Remember that wireless signals bounce of windows and mirrors, thus
decreasing the range. Experiment with different locations until you find one
that is practical and promising. Most people, including myself, like placing
it near the ceiling since most obstructions are nearer to the floor.
It’s always a good idea to monitor the performance of your signal by using
a diagnostic utility. This will help you to identify how strong your signal is
in different locations and whether other electrical equipment is interfering.
Run the utility when the microwave or cordless phone is in use and see if you
notice a difference. Usually your access point will come with its own
monitoring utility.
Installing a repeater for a performance boost
If you’re looking for a boost you can always choose to install a repeater.
The job of a repeater is to receive the signal, regenerate it and rebroadcast
it therefore extending the range of your wireless network. This would sit
somewhere between your Access Point and your wireless client. Some repeaters,
like the Range Expander series from LinkSys, don’t require it to be directly
connected to the network via a cable. However, if security is an issue for you
then be careful as some of these ignore certain security methods such as MAC
address filtering. Also, some repeaters will only repeat wireless signals
coming from its own product family, i.e.: if you have a D-Link Wireless Router
you will have to get a D-Link repeater. The image below demonstrates the job
of a repeater.
The Access Point transmits the signal. As it travels it decreases, until it
hits the repeater and gets boosted. The newly transmitted signal is then
received by an in-range wireless client.
Changing the Antenna
Changing the antenna of your access point can increase signal range and
overall performance. Typical access points come with a 2dB or 4dB gain
antenna but there are one’s available with 8, 14 and even 24dB. Antenna gain
is measured in dBi (decibels-isotropic) which basically means how powerful the
antenna is and how far it can provide a signal. Directional antennas are
suitable for environments where you have a direct line of site from one access
point to another and from access point to client; the signal travels in a
straight line. Omni-Directional antennas distribute their signal in a circular
360 degrees motion over a horizontal pane, which is ideal for square areas.
Install Windows XP SP2
If you are using Windows XP on your wireless client - as I’m sure most of
you are – installing Service Pack 2 would be a good idea. Check the Microsoft
Website for download details. Windows XP Service Pack 2 comes with enhanced
wireless support such as a new network setup wizard, built in support for WPA
(Wi-Fi Protected Access), an updated Wireless Network Connection dialog box
and amongst others, a rather nifty repair feature.
To utilize the repair feature all you have to do is right click the
connection and select Repair or click the button on the support tab of the
status dialog box. This will disable and then re-enable the connection (which
clears many of the error conditions on wireless network adapters), clear the
NetBT cache and flush the DNS cache. I often find that if my connection signal
becomes low after a long period of activity, pressing the Repair button will
boost it up to “Good” or “Very Good” depending on my location.
Network Settings
DHCP Addresses
DHCP configuration errors may also cause problems when connecting to a
wireless network. Some of the newer access points on the market come with
their own DHCP server which usually assigns addresses in the 192.168.0.x
range. If your wired network uses a different range then you will probably
find that wireless network clients are able to obtain an IP address and ping
the access point but communication with other clients will not work. Your
access point configuration interface should allow you to set which address
scope to use. Set this to be the same as that of your other clients. You can
also just disable the DHCP server on the access point and allow clients to
obtain an address from the normal DHCP Server on your network.
Encryption Keys
Double check and re-enter your WEP/WPA encryption keys. Wireless Encryption
will vary depending on which type of network you are connecting to. In Windows
XP, on the Association tab of your wireless network properties dialog box,
verify that your network key has been entered correctly and is valid for the
network you are attempting to connect to.
MAC Address Filters
A great form of security to allow restricted access to your network. As I
had explained in
An Introduction to Wireless Networking Part 1, MAC Address Filters are a
list of MAC addresses belonging to the clients that are allowed access to the
network. This will only permit clients with the specified MAC Addresses to
communicate with the network. Having said this, it may be the reason to your
problem. Verify that the problematic client’s MAC is in the address list. If
the network card had to be changed or a new device purchased recently, be sure
to add it to the list.
Conclusion
After having read this article you should be familiar with common wireless
network connections problems and what you can do to fix them. I hope that you
will now be able to follow these steps when a wireless problem occurs and take
the necessary action in solving such issues. Look out for Part 3 of my
Introduction to wireless networking series in which I will take a closer look
at security, give you some wireless network tips and tricks and also update
you on the latest wireless networking news.
