WLAN Topologies
Scalability

Scalability is the ability to locate more than one access point in the same area. This will increase the available bandwidth of that area for all users local to that access point. In the past, this scalability was limited to only frequency hopping spread spectrum (FHSS) products. DSSS products could not change channels without some reconfiguration. The current Cisco Aironet products are frequency agile. This means that they can look for and use the best channel. There are three separate, 11-Mbps channels available. These channels are completely non-overlapping and non-interfering. Up to a theoretical 33 Mbps per cell can be achieved with 802.11b devices. However, users still only operate at a maximum theoretical value of 11 Mbps, since they can only connect to one AP at any given time.

In the case of 802.11a, there are eight non-overlapping channels, each up to a theoretical bandwidth of 54 Mbps. This means that a maximum of eight discrete systems can reside in the same area, with no interference. Therefore, the highest aggregate total data rate for an 802.11a system is a theoretical 432 Mbps, for a given cell area. Remember that any connected user will still only receive up to 54 Mbps. With more APs, users will have a greater chance of higher data rates.