Voice Over Wireless Networks: Almost Ready for Prime Time?

Chris Taylor, Telecommunications Manager, Metro Toronto Convention Centre had a serious problem. His mission critical Nortel “Companion” 900Mz phone system was no longer supported and he needed a replacement system double quick. With 2 million square feet of open exhibition space spread over two buildings, he needed a communications system that provided roaming and instant communications, an open flexible data network, and a minimum of wires. A year ago, he started looking at wireless networking combined with VoIP (Voice over IP) or VoWLAN (Voice over IP over Wireless) as part of the total networking solution. As Taylor put it, “My three goals were to provide wireless data networking for exhibitors, create a corporate profit center by selling services to the exhibitors, and meet employee data/telecommunications needs. The combination of VoIP and wireless networking fit the bill exactly.”

With 55 million lines and 15% of the voice market, VoIP is an established and rapidly maturing technology. It has been proven to be less expensive to install and maintain; the core equipment is comparable in cost to traditional voice, and it offers many more integration options. Wireless technology is also rapidly maturing, so the next obvious step is to deploy a converged technology. Until a few months ago, the converged technology suffered from proprietary equipment, weak security, and a lack of scalable network management tools: It was not quite ready for prime time. All that has changed in the past year. The VoWLAN landscape is rapidly changing with evolving standards, new equipment, and finally some good management tools. Let us look at some of the issues that were plaguing VoWLAN and how the fledgling industry is successfully addressing them.

According to Bob Myers, CTO and co-founder of Chantry Networks, a company that develops wireless network management systems, VoWLAN is growing rapidly in certain vertical industries like health care, hospitality, retail and manufacturing. Industries where the flexibility, combined voice and data requirements are so compelling that they are willing to forgo the current lack of handset hardware, network management tools and poorly addressed security, standards, and QoS (Quality of Service) issues.

Part of the problem is that wireless is a contention media — the users share the available bandwidth — so wireless will always have overhead issues and more complex management requirements. Another overlooked issue is how to determine good coverage. In an open field, coverage is easy to determine, but most IT people don’t have the specialized knowledge required to plan an installation for a complex environment like a hospital, with all its attendant equipment and building structures.

Myers notes, “Health care’s transition to VoWLAN came about because they had widely deployed 802.11 so they were already comfortable with the technology. The hospitality and retail sectors both have a widely dispersed work force that needs to be in constant communication. Both industries were previously using the 900Mz Walkie-Talkie systems, so conversion to VoWLAN was a natural next step. Beyond those specific industries, uptake has been slow because of the perceived security issues and lake of management tools.” Recently, there has been a major change in perception as companies discover the benefits of increased flexibility, the improved security standards, and the always popular, substantially lower operational costs.

A critical component to the success of VoWLAN is sophisticated wireless network management tools. As Myers puts it, “Unlike all previous computer technology, wireless networking, wireless came back into the enterprise from the SOHO and home markets. With a three node network, you don’t need management tools.” When rolling out enterprise wide wireless, especially VoIP, the need for prioritized data streams, transparent access point handoffs, and seamless security are essential. Chantry offers a management package that is designed to specifically address these issues. Other companies, like Avaya and Cisco who are heavily invested in developing this market, are also working to develop new tools.

Wireless service quality is technologically a step 10 years backwards. For data packet delivery, companies are willing to trade mobility and reduced costs for reliability, but voice packets are more sensitive to perceptible service degradation. As Myers puts it, “You really need to have a max of 150ms to make sure users are not bothered by QoS issues when you are using a VoIP system. Cellular has gotten people used to a lower QoS compared to traditional voice, but not entirely.”

To make matters worse, the WME (Wireless Multimedia Extensions) 802.11e wireless QoS standard will not be ratified until the end of 2004 or early 2005. Most wireless equipment has not yet incorporated any QoS because they are waiting for the emerging standards. Because this is such a critical piece for a successful VoWLAN deployment, some companies are implementing a subset of 802.11e. Another gotcha is that while 802.11b officially delivers 11MB with QoS, the actual useable bandwidth is really closer to 6MB. Remember that 6MB is shared by anyone on the access point. VoIP has a tendency to have small packets with a large overhead. With 10 to 15 VoIP users you are quickly down to unacceptable modem-level data rates. The reality is that with most wireless equipment, planners should expect 6-7 voice calls maximum per channel. With Chandra’s priority queuing and predictive handoffs, they can support up to 15 voice streams in addition to a small amount of data traffic. By limiting the number of voice calls on a single access point, the software can maintain the required QoS.

Wireless security is finally improving with the newer WPA and WPA2 standards, but these emerging standards have not been fully adopted into the VoWLAN equipment yet. 802.11r is a brand new IEEE taskforce created specifically to address VoWLAN security issues. Expect to see handsets incorporating the improved security standards in 6 to 8 months, and new standards in this area in a year or so. According to Myers, part of the problem is the need to re-authenticate every time users move between access points. Session switching can cause unacceptably high delays (up to 500ms) or dropped calls. Obviously the re-authentication process is in direct conflict with the QoS requirements of maintaining the call data stream. Chantry has incorporated a virtual network service that preloads the VoIP session security at the backend as the user roams the network so the call session is transparently switched to the new access point minimizing signal delay.

Unless you were a tiny company that had an IT generalist, the data and telecom support staff have, until recently, not needed to learn each other’s methodologies and equipment. The current trend is to merge the support functions and staff for more efficient operations, but there is still a time lag in training and operational efficiencies, as the staff learn the new equipment and procedures.

Currently there are two main companies in the VoWLAN handset market, Vocera and SpectraLink. SpectraLink owns 75% of the total handset market and the majority of the health care market with systems in 1600 hospitals nationwide. Vocera is startup breaking into retail and health care. Because they were first to market, neither of these are standards based systems. Both Cisco and Symbol (the people who invented barcode scanners) have handsets as well. According to Chris Taylor, Symbol has recently dropped the VoWLAN line to focus on their core market. All the products suffer from short battery life and reliability problems. As PoE (Power over Ethernet), standards and cellphone technology is incorporated, expect to see a plethora of better handsets within the next few months.

How is Chris Taylor doing with his VoWLAN system? He reports that they have had the beta system in place since January. They are planning a full rollout to completely replace the old “Companion” system by September. “The staff loves it. The voice quality is good and roaming is completely transparent. Just make sure all the vendors’ equipment is compatible and integrated. That was the key to success for our installation.”

Should you be seriously considering Voice over IP over wireless LAN solutions today? Well yes and no. Unless you are in the health care, manufacturing, or retail industries where the ROI is especially compelling, the technology is still not quite ready to be heard yet. With the maturing of both the VoIP and wireless technologies, on the surface merging the two emerging technologies might seem to be a terrific idea. However, security issues, poor quality equipment, and bandwidth prioritization considerations point to a technology that is still too immature for anybody to deploy unless they are ready to put up with the bleeding edge phase of the innovation curve. In the next 8 to 12 month there will be numerous new products that will be addressing these and other issues as many innovative technology companies work on solving the problems. Once the issues have been properly addressed and the standards settle down, VoWLAN with its potential to merge data, voice and mobility into one neat package, promises to be something that could transform how companies do business.

Small Business Computing Staff
Small Business Computing Staff
Small Business Computing addresses the technology needs of small businesses, which are defined as businesses with fewer than 500 employees and/or less than $7 million in annual sales.

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