IEEE seeks wireless VoIP solutions

The Institute of Electrical and Electronics Engineers Standards Association (IEEE-SA) has approved two new projects to improve the standard of Voice over Internet Protocol (VoIP) over wireless networks.

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By  Simon Duddy Published  August 4, 2004

The Institute of Electrical and Electronics Engineers Standards Association (IEEE-SA) has approved two new projects to improve the standard of Voice over Internet Protocol (VoIP) over wireless networks. The fast roaming project, IEEE P802.11r, aims to make it easier to use wireless VoIP and other real-time interactive applications. The mesh project, IEEE P802.11s, is designed to extend WLAN range by allowing data to pass through wireless nodes. The IEEE P802.11r project is significant as the increased security emphasis in enterprise wireless networks has caused a slow down in voice performance. Enterprises are now more likely to include authentication at each access point and with each authentication a small delay is caused. This is not noticeable when observing data traffic but causes interruptions in voice. The underlying physical problem is latency and the International Telecommunication Union (ITU) recommends that for voice traffic latency should not exceed 150ms. “Currently wireless devices, including wireless VoIP handsets, can easily roam between access points. The challenge is to allow the devices to do so in a secure manner,” says Dan York, director of product management for mobility solutions. The group will investigate a technology known as Fast Basic Synchronised Subset (BSS) Transition, an ITU term used to describe a group of wireless radio or other communications receivers that can handle signals for users moving among and between coverage areas. The task force is expected to come up with a solution sometime next year. There are options available to companies that want to continue using the technology. “Companies wanting authentication may choose to use the Personal mode of WPA, which is the Wi-Fi Alliance's branding of the parts of 802.11i that involve the use of pre-shared keys between access points,” says York. ”However, as this does not meet the full 802.11i standard, specifically, full support for 802.1x authentication, which the Wi-Fi Alliance terms WPA Enterprise, it may not be allowed in some companies with strict corporate security policies. Those corporations will have to either implement full 802.11i and deal with potential voice quality issues in roaming between access points or wait for 802.11r,” he explains. The second of the IEEE projects (P802.11s) will focus on creating a mesh service standard so wireless access nodes spread over a large area can connect to a main node. This will extend coverage beyond the typical WLAN connectivity limit of 100 metres. In a mesh, a single access point can serve a large facility or broad sensor array. Mesh networks can also allow a fireman to become a node in a communications network in an emergency. Although VoIP over wireless is experiencing teething problems, especially in an increasingly security conscious enterprise environment it has been around for a while and is growing in popularity. “VoIP over wireless is increasingly seen as a requirement for the enterprise,” says Hisham Amili, director of sales and marketing, GCC. “It is now appearing in almost every new tender across geography, sectors, and verticals. Mitel has recently won several projects in the EMEA region where elements of wireless were included,” he adds. Not all analysts agree with Mitel’s optimism however. According to Gartner, building a WLAN that supports high-quality transmission of voice traffic is over twice as expensive as creating one for basic data services. WLAN coverage for data applications can be limited to specific parts of an office complex but coverage for voice calls is invariably wider. Therefore a more a dense configuration of access points is required, which adds to cost. Wireless PBX systems have been available for over 10 years, but have never accounted for more than 12 percent of the PBX lines in service according to Gartner. If VoIP over wireless is do to better the resolution of security and performance related issues must be accompanied by a lowering of equipment cost.

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