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1× Ev-Do (Evolution Data Optimised) Standard

Key Data

The 1× Evolution-Data Optimised, which is abbreviated as EV-DO or 1× EV-DO, is a wireless radio broadband data standard. It has been adopted by a number of CDMA mobile telecommunications service providers across the world, particularly in the USA, South Korea, Japan, eastern European countries, Australia, Canada and New Zealand.

The technology was first standardised by 3GPP2 in 2000 as part of the CDMA2000 standards. Qualcomm started to develop EV-DO in 1999 in a bid to produce a 2Mbit/s downlink for stationary communications, according to the requirements of IMT-2000.

Originally the DO of the standards acronym stood for 'data only'. However, after being ratified by the International Telecommunications Union (ITU), the 'O' was changed to 'optimised' since 'only' had negative connotations for marketing the technology. EV-DO technology is a direct evolution of the 1× (1×RTT) air interface standard, with its channels carrying data traffic only.


In comparison to GPRS and EDGE standards, which have been widely adopted by GSM networks, the 1× EV-DO capability of enabled CDMA2000 networks is much faster. It provides mobile devices (handsets and wireless modem air cards) with air interface speeds of up to 2.4576Mb/s with EV-DO Rev. 0 and even faster speeds of 3.1Mb/s with Rev. A (data only rev A, affectionately known as DORA).

Only devices fitted with 1xEV-DO capable chipsets can take advantage of the higher speeds. High speed downlink packet access (HSDPA) is a rival technology for wide band code division multiple access (W-CDMA) networks. HSDPA has the advantage over EV-DO of being able to maintain voice and data channels simultaneously over a single pair of frequencies.

The system has some real advantages over WiFi, including the fact that it is always on with seamless roaming. Additionally, the signal can travel on the same cell sites as mobile phones, can download and run video clips in real time, there is no 300ft range from the cell tower or ‘hot spot’ and there are not so many security issues.


When deployed alongside a voice network, 1× EV-DO requires a separate radio channel of 1.25MHz. The first revision of the standard was 1x EV-DO Rev. 0 and this is now being superseded by 1× EV-DO Rev. A (DORA), which has already been commercially deployed in Japan.

DORA is also being deployed in the United States by Sprint and Verizon Wireless during 2006 (EV-DO coverage across the USA covers 200 million subscribers across over 220 cities (Verizon and Sprint)). The Rev. A version offers fast packet establishment on both the forward (downlink) and reverse (uplink) links along with air interface enhancements that reduce latency and improve data rates.

In addition to the increase in the maximum downlink rate from 2.4576Mb/s in Rev. 0 to 3.1Mb/s, DORA also has a 12-times improvement in the maximum uplink data rate, from .15Mb/s to 1.8Mb/s. EV-DO Rev. A also supports low latency services (as low as 50ms) including VoIP and Video Telephony on the same carrier with traditional Internet packet data services. Latency for Rev 0 was 150–200ms but for rev A is in the double digit range making real time services a much better prospect.


Even DORA is now due to be superseded, with the wireless communications market constantly striving for better and faster services. 1× EV-DO Rev B (DORB) specifications have now been developed.

"Even DORA is now due to be superseded, with the wireless communications market constantly striving for better and faster services."

DORB is the evolution of DORA and in addition to all that is provided in Rev A, provides additional enhancements such as: higher rates per carrier (up to 4.9Mbps on the downlink); higher rates by bundling multiple channels together (this can enhance user experience and enables new services such as high definition video streaming); reducing latency for services such as gaming and video telephony, due to statistical mutiplexing across channels and hybrid frequency re-use which reduces the interference from the adjacent sectors and improves the rates that can be offered especially to the users at the edge of the cell.