Voice over Wi-Fi
Wi-Fi is poised to play a key role in the evolving market for converged devices, with more than 500 million Wi-Fi-enabled handsets predicted to be sold per year by 2012 (source: ABI Research, 2007). This growth is driven by the flexibility and convenience of Wi-Fi combined with the increased popularity of Voice over Internet Protocol (VoIP) applications.
Voice services are no longer restricted to the wireline and wireless networks that were traditionally designed to transport voice traffic. Today, virtually any IP-based broadband connection can support voice. VoIP applications, however, require special attention to call quality carrying voice traffic between devices that have IP connectivity.
Voice is an application that has unique requirements due to its high sensitivity to network delays. In particular, voice calls are extremely sensitive to latency, jitter and packet loss during transmission. By comparison, downloading a large file or Internet browsing typically requires more bandwidth. Perceived performance of data applications degrades gradually (i.e. slow file download). In contrast, voice conversations may become distorted or altogether inaudible.
A single Wi-Fi network may simultaneously support phones, laptops, gaming devices and printers, with each device transmitting data, audio, voice, video or some combination of these traffic types. To optimize the overall network performance while providing consistent and reliable support for voice over Wi-Fi applications, voice traffic has to be prioritized over data, audio, or video traffic.
The Wi-Fi Alliance has recognized that additional certification testing is required to support voice over Wi-Fi applications.
Home and Small Office Environments
The Wi-Fi Alliance is currently developing a certification program that will test the performance of the Wi-Fi implementations in voice over Wi-Fi applications, under real-life conditions that include both voice and data traffic streams, in network configurations common in home and small office environments.
We have identified a set of minimum performance criteria that have been identified to help ensure good voice quality in a typical user environment. In the planned program, certification testing will be aimed at establishing optimal support for voice applications within the Wi-Fi network and preserving the quality of the voice call transmitted over the IP channel. Devices certified under this program, when available, will enable users to make high-quality voice calls with the same reliability and convenience they expect from data over Wi-Fi applications and wired VoIP calls.
Large Enterprise Environments
Large enterprise networks require both voice quality and data traffic management. The Voice-Enterprise program builds on the core performance testing elements of the Voice-Personal program by adding features to support the unique needs of large networks. The program validates support for seamless transitions for voice applications across the Wi-Fi network, where voice users can roam across multiple access points while maintaining high voice quality, and requires WPA2-Enterprise class security.
WMM-Admission Control, which is a required element of the Voice-Enterprise certification, optimizes traffic management by admitting only those traffic streams that an AP can support at a given time, enabling load balancing, and supplying a consistent experience to connected users.
The convenience, flexibility, ubiquity and cost-effectiveness of Wi-Fi have made voice a compelling application for many Wi-Fi users. Wi-Fi device users, manufacturers, operators should look for devices that are Wi-Fi CERTIFIED™ for voice applications, tested to support an improved and consistent experience of voice quality and performance, while preserving interoperability with existing Wi-Fi CERTIFIED equipment.