Talking on a mobile handset. For a concept that seems so familiar and
commonplace, the underlying infrastructure--and associated complexity--
required to support VoWLANs (voice over wireless LANs) has been somewhat
intimidating. Helping to tackle all the related issues and bring some clarity to
the marketplace are standards bodies such as the Wi-Fi Alliance and the IEEE
(Institute of Electrical and Electronics Engineers). This week, we'll look at
what the Wi-Fi Alliance is doing.
Formerly WECA, the Wi-Fi Alliance was formed in 1999 to provide a basic
interoperability testing ground for the new IEEE 802.11 equipment flooding the
market. Initial standards focused on 802.11b, then on 802.11g and 802.11a,
with testing along the way for WEP (wired equivalent privacy) support. In 2002,
the alliance developed WPA (Wi-Fi protected access) as an interim but
compatible solution for the still developing IEEE 802.11i security standard. Since
that time, the Wi-Fi Alliance has become more expansive in its scope.
Early in 2004, the alliance formed the Voice over Wi-Fi task group. Made up of
wireless infrastructure, handset and test equipment vendors and headed up by
Meru Networks' Chief Software Architect Joe Epstein, this group has focused
on two cases: home and enterprise. Similar to the division between WPA pre-
shared keys (home) and WPA with 802.1X support (enterprise), the home case
is simpler because only one AP (access point) is required, so little emphasis is
placed on roaming capabilities. It will include some level of QoS (quality of
service), likely in the form of WMM (Wi-Fi multimedia) and perhaps WMM-SA (Wi-
Fi multimedia scheduled access). The average number of traditional handsets in
the home case ranges from two to four, so security provided via manually
entered WPA pre-shared keys should be enough. The MRD (marketing
requirements document) for the home case has been completed, and the Voice
over Wi-Fi technical task group is now generating the methodology and
producing test cases.
With some of the groundwork laid, the home case has been expanded and
extended into the enterprise case, where issues such as roaming and battery
life become more significant. Because pre-shared keys have limited scalability in
the enterprise, network-based authentication schemes will have to be
constructed to accommodate the cramped or reduced keypads found on
VoWLAN devices. The Wi-Fi Alliance is concurrently working on the "Simple
Configuration Security" concept, which ideally will draw on the features found in
Broadcom's SecureEasySetup and Buffalo Technology's AOSS. This push-button
security mechanism allows even headless devices to create secure connections
without a keyboard and monitor. The Voice over Wi-Fi technical task group
hopes to complete the enterprise case in the first half of 2006.
Similar to how WPA was an initial subset of IEEE 802.11i, WMM is a subset of
the almost completed IEEE 802.11e. WMM is a QoS standard that specifies four
levels of priority for traffic, of which voice is the highest. Certification
began last September, but the uptake by VoWLAN handset manufacturers has
been disappointing. Cisco, which just released new firmware for its enterprise
7920 VoWLAN handset in June, did not include WMM support. SpectraLink
included WMM support in its latest release, but the company will continue to
pitch its own proprietary SVP (SpectraLink Voice Protocol) in the interim until
enterprises support WMM throughout their infrastructure.
