The throughput of a wireless LAN (WLAN) is said to be around 54 Mbps for 802.11g and 11 Mbps for 802.11b. If your computer is using the 802.11b standard and the source is using 802.11g, you will not receive speeds in excess of 11 Mbps. Apart from this simple mismatch, problems with WLANs abound: high utilisation, coverage holes, obstructions, interference and bad access point placement can also affect the speed of the network.
WLANs work on the radio frequency and use air as the medium. Since air has a time lag while sending and receiving signals (as compared to copper), it causes high collision rates and retransmission. These collisions result in noise, which in turn affects network speeds. Gadgets such as microwave ovens affect the performance of a WLAN as well. Other objects include cordless phones that run on the 2.4 GHz frequency, as well as other WLANs. If there are other WLANs within the area, change your WLAN to non-conflicting channels. It’s important to note here that there are only three channels available in the 2.4 Ghz spectrum—1, 6 and 11. If you have a microwave or cordless phone, place them in a position that’s well away from your normal work area and access points.
If you find that there are other WLANs using all three channels, increase the transmitting power of your WLAN. Remember to keep access points closer to each other to improve the signal to noise ratio. Also, if too many users log on to your network at the same time, your network performance will degrade—keep access points closer together and reduce the transmission power (the same concept used in your mobile phone). This reduces the number of users per access point.
Obstructions in the WLAN field can also affect performance. Properly survey the area that you want to cover with your WLAN and place access points smartly. Walk about with a laptop and look for coverage holes—spots in your coverage area where network strength drops drastically (even to zero). Shift your access points about and increase transmission strengths to plug these holes. You could also try to get hold of directional antennas, and point them in such a way so as to plug coverage holes.
Sometimes, the access points themselves are to blame, due to lockdowns, broken antennas, use of incorrect power adaptors or varied output frequencies. A reboot of the access point should solve a lockdown problem. Make sure to upgrade the firmware regularly, and also only use adaptors meant for the same model.