Wireless Ethernet, also known as IEEE 802.11b, is becoming more popular as the cost to implement decreases and availability of more products increase. The Apple AirPort and Lucent Orinoco cards have brought wireless into the home market, allowing a person to have Ethernet access anywhere in their house, and schools are deploying Wireless Ethernet across the campus. It's now available at airports, schools, many high tech companies, and soon upscale coffee shops.
Given that 802.11b is most popular for laptops, since they are portable, tuning for performance is not as great importance as tuning for power usage. Using 802.11b is often very power-consuming and can quickly drain the batteries. Some cards (such as the Lucent Orinoco card) have the ability to turn its antenna on and off at regular intervals. Instead of the antenna being on all the time, it turns on a few times a second. With the transmitter being turned off now more than half the time, the battery usage is decreased. There is an increase of latency and decrease in data rate.
To set the power management of the card, you will need to have the wireless tools, available with many distributions. This package contains three commands for managing your wireless card: iwconfig, iwspy, and iwpriv.
The iwconfig is an extension of ifconfig. Run without any options, it will check all available interfaces and checks for wireless extensions. If there are any, it will report similar to the following:
wvlan0 IEEE 802.11-DS ESSID:"default" Nickname:"HERMES I"
Frequency:2.437GHz Sensitivity:1/3 Mode:Managed
Access Point: 00:90:4B:08:13:1C
Bit Rate:2Mb/s RTS thr:off Fragment thr:off
Power Management:off
Link quality:8/92 Signal level:-88 dBm Noise level:-96 dBm
Rx invalid nwid:0 invalid crypt:0 invalid misc:599 |
As you can see, the output tells you a variety of statistics on the link. My current bit rate is 2Mb/s, probably because my link quality is so low. The link quality is 8 out of 92, indicating that I should either move my laptop, move my base statiopn, or throw out my 2.4Ghz phone.
You can also see that power management is currently off. Since my laptop is plugged into the wall, this is not a concern to me. If I did want to activate the power management, I would use:
# iwconfig wvlan0 power 1
# iwconfig
iwconfig
lo no wireless extensions.
wvlan0 IEEE 802.11-DS ESSID:"default" Nickname:"HERMES I"
Frequency:2.437GHz Sensitivity:1/3 Mode:Managed
Access Point: 00:90:4B:08:13:1C
Bit Rate:2Mb/s RTS thr:off Fragment thr:off
Encryption key:off
Power Management period:1s mode:All packets received
Link quality:11/92 Signal level:-84 dBm Noise level:-95 dBm
Rx invalid nwid:0 invalid crypt:0 invalid misc:0
# |
The power management is now set to turn the transmitter on only once per second. By default, the time is in seconds, but but appending m or u to the end of the number will make it milliseconds or microseconds.
All that being said, here are a few ways in improve the link quality of your system. Any combination of these will work, so do not expect one method alone to work.
Check the infrastructure and building materials. Thick wood or metal walls will cause a lot of interference. Line of sight to the base station is best.
Some base stations and wireless cards support external antennas. They will greatly improve the range and quality of the link.
Move the base station around. Line of sight is best, but not required.
Turn off other devices that use 2.4Ghz. Some phones and other wireless gadgets use the same frequency, and if not built properly, will cause the wireless Ethernet cards to continually scan through frequencies for the correct one, dropping performance.