[IP] The Great IP Debate
Begin forwarded message:
From: Dewayne Hendricks <dewayne@xxxxxxxxxxxxx>
Date: July 11, 2004 7:56:36 PM EDT
To: Dewayne-Net Technology List <dewayne-net@xxxxxxxxxxxxx>
Subject: [Dewayne-Net] The Great IP Debate
Reply-To: dewayne@xxxxxxxxxxxxx
The Great IP Debate
While the conceptual merits of IP networks are impressive, the economic
viability and technical feasibility for wireless networks remain
questionable.
By Sue Marek
July 1, 2004
Wireless Week
<http://www.wirelessweek.com/article/CA432357?
spacedesc=Features&stt=000>
Telecom visionaries have long painted an idyllic picture of the
converged wireline/wireless services that will one day be possible as
operators migrate to all IP-based networks. The allure of all-IP
networks is compelling because at the IP layer, both voice and data
traffic are transported as packets of data, allowing carriers to
efficiently deploy new services such as real-time multimedia with
integrated voice and video. And once both wireline and wireless
networks get to a common IP platform, telecom carriers could seamlessly
merge their services and offer customers a truly bundled package.
But at the same time, wireless operators are somewhat leery of the
IP-based services that these 3G networks can accommodate, particularly
VoIP. The technology offers some advantages when it comes to deploying
advanced services or managing the network elements; having an all-IP
network instead of separate voice and data networks means that carriers
have fewer pieces of equipment to deploy and maintain. Yet industry
insiders say that VoIP, in some instances, is a less efficient
technology than traditional circuit-switched voice networks, which have
been optimized to use spectrum very proficiently.
VoIP or Circuit Switched? "All-IP networks in theory sound great," says
Jane Zweig, CEO of The Shosteck Group. "But with the particulars of
radio on the mobile side, migrating to VoIP requires over-provisioning
of the network."
For example, in an IP environment, voice packets contain a lot of extra
information, called headers, to ensure they are routed to the right
location. These headers take up a lot of bandwidth and therefore are
less efficient — and slower. To maintain service quality, voice packets
must be delivered in a timely manner or else they will suffer some
degradation.
In addition, carriers have invested so much in their legacy voice
networks that many hesitate to move voice traffic from the legacy
network to an IP platform. "Circuit switched is not going away. It's a
legacy system that will be with us for a long time," says John Marinho,
vice president of marketing and offer management at Lucent's Mobility
Group. "But VoIP is the cornerstone that will enable a lot of things to
be possible in the next several decades."
Exactly what voice services will be used for VoIP and what will remain
on the circuit-switched network is uncertain. However, carriers are
putting VoIP on their migration paths. "VoIP is part of the long-term
solution" for wireless networks, says Rod Nelson, executive vice
president and chief technology officer of AT&T Wireless. "It offers
lots of potential for advanced services such as PTT or multimedia calls
with video and voice. But for most normal cellular voice traffic, it
doesn't offer huge economic gains compared to what has already been
built into the existing system."
The Path to VoIP From a technical standpoint, operators could deploy
VoIP in current-generation networks to provide high-quality service.
But observers say wireless networks need a lot of bandwidth and a
bigger uplink than existing UMTS Release 99 technology or the current
iteration of 1XEV-DO, Rev. 0. If carriers migrate to the next versions
of these technologies — high-speed data packet access (HSDPA) or
1XEV-DO Rev. A — uplink speeds will increase, making VoIP much more
viable.
On the GSM side, Cingular Wireless recently issued a request for
proposal to the vendor community for UMTS/HSDPA infrastructure, which
it plans to deploy across its network. The carrier is testing UMTS in
its home market of Atlanta using Lucent gear; the HSDPA component
involves a software upgrade to the UMTS equipment to support data
speeds of up to 14.4 Mbps downstream. According to Lucent's Marinho,
HSDPA provides speeds of 384 kbps upstream, which is still limited but
will support VoIP. Marinho adds that another UMTS uplink solution in
development, called enhanced uplink data channel (EUDCH), could give
GSM operators 4 Mbps in both directions, making it very compatible with
VoIP.
Still, Cingular's deployment of UMTS and HSDPA technologies doesn't
necessarily mean it will automatically migrate to VoIP, according to
Kris Rinne, acting chief technical officer of Cingular Wireless.
However, Rinne says that IP-based services are appealing. "IP services
are much more efficient regardless of whether it is in radio spectrum
or backhaul transport," Rinne says. "It's more efficient than circuit
switched, but you must constantly balance that efficiency with
quality."
On the CDMA side, 1XEV-DO Rev. A has an uplink speed of 1.8 Mbps with
3.1 Mbps downstream, making it possible to send voice packets with
header information over Rev. A and not cause degradation of voice
quality. Although no U.S. CDMA carrier has announced that it was
testing or planning to migrate to Rev. A, Verizon Wireless Chief
Technical Officer Dick Lynch said at CTIA Wireless 2004 that it was
possible the company would continue on its EV-DO path and perhaps at
some point offer a type of voice service over EV-DO.
Joining Verizon on the EV-DO path is Sprint PCS, which earlier was
examining EV-DV as its preferred choice but late last month formally
announced that equipment availability and market timing prompted it to
forge ahead with 1XEV-DO. Sprint could decide to implement 1XEV-DV as
it is building out its 1XEV-DO network, but DV equipment is not
expected to be available until 2006. Although 1XEV-DV offers both a
voice and data component, the voice portion of EV-DV is circuit
switched. According to Peter Jarich, senior analyst, wireless
infrastructure at Current Analysis, EV-DO Rev. A gives DO more
potential as a voice network. "It's too early to say, but DO does seem
more compelling," Jarich says.
Timetable For VoIP Though the debate over VoIP vs. circuit switched may
be heating up among the carriers and vendors, VoIP over wireless likely
will not be a reality for some time. According to Kai Konola, director
of strategy and business development at Nokia Networks, one form or
another of VoIP will migrate to cellular networks in the next four or
five years. However, the mass market won't see VoIP over cellular for
some time. "The capabilities of the radio networks to support VoIP in
mass scale is not optimal," Konola says. "It makes more sense for
carriers to provide voice over circuit switched."
The migration from circuit switched to VoIP likely will be gradual.
According to Konola, many other factors are involved such as having
terminals capable of handling VoIP, which require a lot of processing
power.
Still, once VoIP does make it to the cellular network, most vendors
believe that at some point the circuit-switched network will go away.
"People will outgrow the legacy network," says Bruce Gustafson,
director of strategic marketing, wireless networks at Nortel Networks.
And as carriers invest more in the packet network, gradually the mix of
subscribers on the IP core vs. the circuit-switched network will
change. However, Gustafson also sees that different carriers will make
the move to VoIP at different times based on their business strategies.
"It also depends upon how wireless standards are implemented,"
Gustafson says.
Others are less bullish on VoIP being offered via the cellular network,
primarily because of the business case. "The benefit of doing VoIP over
the air interface isn't that clear," says Lars Nilsson, director of
business strategies at Ericsson. "The systems are not there."
Others echo that sentiment. "The economics of VoIP in wireless are
different than wireline," Nelson says. "I don't know that the same
drive is there, particularly for implementers of UMTS, which brings
into it integrated voice capability. If the technology you are
deploying doesn't have a voice solution, you would be more motivated to
do VoIP. With UMTS, it's less urgent."
Gustafson says carriers already are implementing VoIP in the core of
their networks to backhaul traffic. Exactly where the carrier converts
the traffic from circuit switched to VoIP depends on the network
topology. The benefit, according to Gustafson, is carriers can
transport more traffic using VoIP in the core. "Instead of having a
half-used switch here and there, we are seeing carriers ask for one big
switch that will carry 50 percent voice traffic and 50 percent data
traffic," Gustafson says.
VoIP may be garnering industry buzz right now, but how it will actually
make its way to the cellular network is subject to debate. For wireless
operators to realize the vision of truly converged services, they need
to move to an all-IP based network. But significant questions remain as
to whether it will be economically and technically viable for the
long-term.
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