Configuring Wireless VLANs
If you use VLANs on your wireless LAN and assign SSIDs to VLANs you can create multiple SSIDs by using any of the four security settings defined in the “Security Types” section. A VLAN can be thought of as a broadcast domain that exists within a defined set of switches. A VLAN consists of a number of end systems, either hosts or network equipment (such as bridges and routers), connected by a single bridging domain. The bridging domain is supported on various pieces of network equipment such as LAN switches that operate bridging protocols between them with a separate group of protocols for each VLAN.
See Configuring Wireless VLANs at Cisco.com for more about wireless VLAN architecture: http://www.cisco.com/en/US/docs/routers/access/wireless/software/guide/
wireless_vlans.html
Source: http://www.cisco.com/c/en/us/td/docs/routers/access/1900/software/configuration/guide/Software_Configuration/wlan.html#pgfId-1061745