VoWLAN might be the chocolate and peanut butter of networking, but the convergence of VoIP and wireless freedom has its share of snags. Here's what you need to know.
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.
Approaching Technological Liftoff
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
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.
Wireless Network Management
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
Continued on Page 2: What Else is There to Think About?
Continued From Page 1
QoS (Quality of Service) and Reliability
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.
Staffing and Operational Issues
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.
Hardware What Hardware?
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.
Are We There Yet?
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
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.
Beth Cohen is president of Luth Computer Specialists, Inc., a consulting practice specializing in IT infrastructure for smaller companies. She has been in the trenches supporting company IT infrastructure for over 20 years in different industries including manufacturing, architecture, construction, engineering, software, telecommunications, and research. She is available for consulting to help your company identify the right IT infrastructure to meet your business objectives.