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Dedicated to Data

HDR Offers Service Providers the Data speeds for Evolution to 3G
By Chris Goldman, Staff Writer 

In the drive to accelerate wireless-data throughput, technologists have
turned speed and spectral efficiency into an art form. And in the case
of high data rate (HDR), Qualcomm is the Picasso of proficiency, the Van
Gogh of velocity. Qualcomm's patented HDR technology was approved this
summer by the CDMA Development Group (CDG) as Phase I of 1XEV - a 3G
technology with a peak data rate of 2.4Mb/s on a data-only channel.
(Phase II will encompass data and voice improvements, but has yet to be
decided.) Sprint PCS and Verizon Wireless are conducting trials of
HDR-based solutions, as are KDDI in Japan and KT Freetel in Korea. 

This 3G advancement will enable networks to efficiently carry
next-generation data services and mobile Internet applications to
subscribers. Vendors are providing HDR primarily as a channel-card
upgrade that along with new software will allow providers to build on
their current 1X investments, hence the name "1XEV," for evolution.

The business case is clear: 1XEV uses current 1X equipment as a
springboard to faster data rates and saves providers money and spectrum
along the way.

Talking 'Bout an Evolution

When the wireless industry first started talking about transmitting more
than voice across digital networks, speeds were incredibly slow - around
14.4kb/s using the IS-95A standard, which evolved to IS-95B (64.4kb/s)
and then 1X - also called 1XRTT (144kb/s).

The benefits provided by these standards included doubling voice
capacity and increasing data rates. And the market is eagerly
anticipating the 2001 roll-out of 144kb/s networks by major providers. 

But engineers at Qualcomm decided there were still problems to be
solved, said Kimberly Kleber, director of product marketing for HDR.

"What Qualcomm started looking at was the voice channel that is being
shared as a data channel," Kleber said. "And the question that came to
some of our engineers then was, 'How can we get a higher data speed than
what is going to be achieved in this shared 1X mode?' and 'How can we
ensure higher data speeds?' The engineers started really focusing on the
fact that when you separate voice and data, you have certain benefits.
You're no longer concerned about latency requirements of voice. Digital
has done a great job of making sure the voice quality is maintained. But
in doing that, the overhead that's required for that channel to maintain
that voice quality essentially degrades the ability to handle data
efficiently and optimally. With HDR, what happens is we take a dedicated
1.25MHz channel, a narrowband channel, and optimize it for packet data.
By optimizing it for packet data, we could then allow the channel to
burst to any single user at a given instant and send the full power of
that sector."

The bursts are sent in 1.67ms packets at the peak rate of 2.4Mb/s,
Kleber said. Average throughput rates are closer to 1Mb/s, according to
service providers testing the technology.

"You don't get data that fast sitting at a desk," Kleber said. "It's a
compelling technology. And HDR is a technology that can bring this
wireless-Internet revolution quicker."

A big reason is spectral efficiency. By transmitting at data rates of
2.4Mb/s over the 1.25MHz of spectrum, providers avoid having to upgrade
to a wideband 5MHz channel, Kleber explained. 

The 1XEV technology is being tested now and should begin deployment in
late 2001 or 2002, she said.

Provider Proving Ground

Over the last two years, Sprint PCS has found through trials that 1XRTT
will yield a tenfold increase in data rates - from 14.4kb/s to 144kb/s -
as well as improved voice capacity and battery performance on handsets.

The provider plans to roll out 1XRTT at the end of 2001, according to
Oliver Valente, Sprint PCS CTO.

"What 1XEV will do is take us to the next plateau of data, which is up
to 2.4Mb/s," Valente said. "1XEV is based on HDR, and we had HDR in our
labs a year ago and liked what we saw. But we had issues with making
sure it fit nicely with the 1X evolution path, in terms of
upgradeability to our network."

Rather than installing all new radio infrastructure, which was what was
originally envisioned with HDR, Sprint PCS needed a more cost-effective
upgrade, he said.

Through standards discussions with other providers and vendors, an
agreement was reached on the most effective way to bridge HDR into the
1X evolution path, Valente said.

"The goal is to try and have it standardized by the end of the year and
start seeing commercial products in '02 some time," he said.

In order to maximize its investment in 1X infrastructure, Sprint PCS is
using a multicarrier-base-station approach for its 1XEV solution.

Qualcomm's Kleber explained that a vendor such as Lucent can take an
existing multicarrier base station and install both 1X and HDR channel
cards, thus housing both types of technology.

Ed Chao, Lucent senior manager for 3G CDMA data, said this is exactly
how the company upgrades its Flexent base station, which Sprint
currently is using for 1X and will continue to use for 1XEV.

"Upgrading is very simple," Chao said. "We use the existing shelves and
add a channel card - a simple card upgrade as well as some software in
the same base station."

Although Sprint now is committed to 1XEV, the decision was not always
clear, Valente said. 

"Qualcomm was the one that initially developed HDR," he said. "But there
were some competing proposals put on the table by Motorola with 1Xtreme.
We liked a lot of those ideas, but we really have sort of put those in a
second phase of 1XEV. It hadn't been as developed as HDR. We were
concerned that if we focused on 1Xtreme that we would lose time to
market. What we've said is we liked a lot of those concepts and are
trying to incorporate those into the next generation, which is beyond
1XEV. We've worked with Qualcomm, Lucent, Nortel, Motorola, Samsung,
Ericsson, just to name a few of the vendors involved in these
discussions to date."

Beyond HDR

Phase II of the CDG's standards process will determine what technology
will encompass both data and voice, hence one of its working names,
1XDV. However, the technology that will be chosen for Phase II is far
from decided, according to Qualcomm's Kleber. 

"Phase II, at this point, is being evaluated and doesn't have a solution
yet," she said. "(The CDG) is evaluating 1Xtreme or LAS-CDMA (large area
synchronized-CDMA) or an evolution of HDR. There will be a technology
that will fill this Phase II, which will be totally new. And Phase II is
intended to give you high data speeds and voice."

"Right now, Motorola, Nokia and others are positioning their technology
proposals as the eventual baseline for the DV technology, the second
phase," said Neal Campbell, Motorola director of CDMA product
operations, adding that the DV phase is scheduled for a draft standard
for May of next year. Motorola's proposed 1Xtreme technology will be
considered along with others - many of which reach data speeds of 5Mb/s
or faster.

"The DO (data only) space will allow for 600kb/s average data rates with
peak rates of better than 2Mb/s," Campbell said. "For the DV proposals -
at least I can speak of (1Xtreme) and the LinkAir (LAS-CDMA) technology
- those proposals are trialing and proposing to get to 5Mb/s peak data
rates with average data rates of 1Mb/s."

According to LinkAir, which conducted a trial call on LAS-CDMA Aug. 15
in Beijing, the technology offers 20 times the voice coverage of
existing 2G networks, while increasing data speeds to 5.53Mb/s. LAS-CDMA
is compatible with GSM and CDMA networks, as well as the major
international 3G standards. And LinkAir refers to it as a bridge
standard between 3G and 4G.

As with 1XEV, the Phase II solution - whether it ends up being 1Xtreme
or LAS-CDMA - could be installed on existing 1X multicarrier base
stations, needing only a channel card and software upgrade.

Although existing network infrastructure can be leveraged for Phase II,
providers likely will need additional spectrum, Campbell said.

"When you look at the data rates (5Mb/s) that we are proposing on such a
narrow channel (1.25MHz), you do start asking yourself, 'What is the
viability or necessity for a 5MHz-wide channel for wireless
communications?'" Campbell said. "If we can play out these data rates of
5Mb/s peak and 1Mb/s average that we believe is quite possible, my guess
is what we will start to see is a move to greater spectrum trunks, from
1.25MHz carriers to the wider carriers to further increase the capacity
and capabilities."

Wireless data's broad popularity remains to be shown, however. Only time
will tell what technology truly will match consumer demand.