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.