Aruba Wireless Networks introduced a software module that enables secure voice over Wi-Fi (VoFi) using its line of WLAN switches. Supporting VoFi requires an architecture that supports fast handoffs as users move across multiple access points (APs) in the network. Handoffs must take under 50 milliseconds in order to not impact voice quality. Aruba said its centralized architecture borrows from the best practices of cellular networks and eliminates the need for APs to talk to each other in order to maintain user state information.
Aruba said its architecture enables inter-AP handoff times well under 10 milliseconds. To maintain QoS, the design uses stateful voice flow classification (VFC) technology to allow mixed voice and data traffic coming from a single device, such as a laptop or PDA, to be automatically identified and prioritized without having to alter the infrastructure in any way. The Aruba APs and WLAN switches support multiple queues that can used to prioritize traffic and have built-in support for the emerging IEEE 802.11e / WME (eight hardware queues in each AP) quality of service specification.
A dynamic Radio Resource Management (RRM) capability can be used to tune the RF environment for optimal user experience. For instance, when a voice call is being initiated, Aruba’s VFC automatically reserves the required amount of bandwidth in the air, can deny the call due to congestion or redirect the call to another AP better able to support it. Aruba’s system is capable of triangulating an 802.11 signal to within five meters and visually depict the location of the RF source on a floor plan.
Aruba said its system can support over 5000 simultaneous voice calls on a single Aruba 5000 WLAN switching system with up to 256 APs. Aruba’s thin APs have also been tested to support greater than 20 voice calls per 802.11b radio.
Aruba also announced that it is working with VoFi equipment suppliers, including SpectraLink, TeleSym and Vocera to deliver integrated and fully-interoperable voice over wireless solutions that include VoFi phones, PC- and PDA-based soft phones and voice communications badges. http://www.arubanetworks.com/
