Evolution-Data Optimized
1x Evolution-Data Optimized, abbreviated
as EV-DO or 1xEV-DO and often EVDO, is a wireless
radio broadband data standard adopted by many CDMA
mobile phone service providers in Japan, Korea, the
Czech Republic, Russia, Latvia, Romania, Portugal,
Brazil, Israel, the United States, Australia, Canada,
New Zealand, Venezuela, Angola, Mexico, Norway and
Puerto Rico. It is standardized by 3GPP2, as part
of the CDMA family of standards. 1xEV-DO is pronounced
"Wun-Ex E-Vee-Dee-Oh." It is commonly referred
in the industry as DO ("Dee-Oh").
Background
The initial design of 1xEV-DO was developed by Qualcomm
in 1999 to meet IMT-2000 requirements for a greater-than
2-Mbit/s downlink for stationary communications. Initially,
the standard was called HDR (High Data Rate), and
was renamed to 1xEV-DO after it was ratified by the
International Telecommunications Union (ITU); it was
given the numerical designation IS-856. Originally,
1xEV-DO stood for "1x Evolution-Data Only",
referring to its being a direct evolution of the 1x
(1xRTT) air interface standard, with its channels
carrying only data traffic. (The title of the 1xEV-DO
standard document is "cdma2000 High Rate Packet
Data Air Interface Specification", as cdma2000
(lowercase) is another name for the 1x standard, numerically
designated as IS-2000.) Later, likely due to the possible
negative connotations of the word "only"
in its marketing, the "DO" part of the standard's
name 1xEV-DO was changed to stand for "Data Optimized".
So 1xEV-DO now stands for "1x Evolution-Data
Optimized" [1], providing a more marketing-friendly
emphasis that the technology was optimized for data
transfers.
Compared to the 1x (1xRTT) networks still being used
by operators, or the GPRS and EDGE networks employed
by their GSM competitors, 1xEV-DO is significantly
faster, providing access terminals (mobile devices)
with air interface speeds of up to 2.4576 Mb/s with
Rev. 0 and up to 3.1 Mb/s with Rev. A. Only terminals
with 1xEV-DO chipsets can take advantage of the higher
speeds. HSDPA is a competing technology for UMTS (W-CDMA)
networks standardized in 3GPP. HSDPA has the advantage
of maintaining voice and data channels simultaneously.
While possible in a CDMA deployment, no operator or
phone manufacturer has introduced a phone with the
required chipset(s) to demodulate both the cdma2000
voice and 1xEV-DO channel.
When deployed with a voice network, 1xEV-DO requires
a separate radio channel of 1.25 MHz. The successor
to the first revision of the standard, 1xEV-DO Rev.
0, is called 1xEV-DO Rev. A, and is currently being
commercially deployed in Japan. Rev. A will be deployed
in the United States by Sprint and Verizon Wireless
in 2006. Rev. A offers fast packet establishment on
both the forward and reverse links along with air
interface enhancements that reduce latency and improve
data rates. In addition to the increase in the maximum
downlink (forward link) data rate from 2.4576 Mb/s
in Rev. 0 to 3.1 Mb/s, Rev. A has a 12-times improvement
in the maximum uplink (reverse link) data rate, from
.15 Mb/s to 1.8 Mb/s. EV-DO Rev. A supports low latency
services including VoIP and Video Telephony on the
same carrier with traditional Internet packet data
services. EV-DO Rev. The air-interface latency specifications
have not been published, however several Qualcomm
documents note latency in the "low double digit"
with the highest RSVP settings. This compares favorably
with Release 0 air-interface latencies of 150-200
ms.
Potential Competing Standards
Motorola proposed a new system called 1Xtreme as an
evolution of CDMA2000 1x, but it was rejected by 3GPP2
standardization body. Later, a competing standard
called 1xEV-DV (which was developed by Qualcomm, Lucent,
Nokia, Motorola, etc. in 3GPP2) was proposed as an
alternate evolution of CDMA. 1xEV-DV stands for Evolution-Data
and Voice, since the channel structure was backwards
compatible with IS-95 and IS-2000 (1xRTT), allowing
an in-band network deployment. (1xEV-DO requires an
overlay network when deployed in mixed mode.)
At the time, there was much debate as to the favorability
of DV and DO. Traditional operators with an existing
voice network preferred deploying DV, since it does
not require an overlay. Other design engineers, and
newer operators without a 1x voice network felt that
EV-DO was a superior choice to 1xEV-DV because it
did not have to be backward compatible, and thus was
free to explore different pilot structures, reverse
link silence periods, improved control channels, etc.
In addition, since 1xEV-DO uses an IP network and
does not require a SS7 network and complex network
switches such as an MSC (mobile switching center),
the network cost is less than that of 1xEV-DV. Another
factor that affected operators' decision to use 1xEV-DO
was equipment was not available for 1xEV-DV in time
to meet market demands whereas the 1xEV-DO equipment
and mobile ASICs were available and tested by the
time the 1xEV-DV standard was completed. As a result,
the 1xEV-DV standard was less attractive to operators,
and has not been implemented. With the announcement
by Verizon Wireless and later Sprint Nextel in 2004
of plans for deployment of 1xEV-DO, and similar announcements
by smaller operators in 2005, Qualcomm in March 2005
suspended development of 1xEV-DV chipsets, and focused
its efforts toward improving the 1xEV-DO product line.
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