Learn more about EVDO
or Evolution-Data Only
, etc.) is a telecommunications standard for the wireless transmission of data through radio signals, typically for broadband Internet access. It uses multiplexing techniques including code division multiple access (CDMA) as well as time division multiplexing (TDM) to maximize both individual users' throughput and the overall system throughput. It is standardized by 3rd Generation Partnership Project 2 (3GPP2) as part of the CDMA2000 family of standards and has been adopted by many mobile phone service providers around the world â€“ particularly those previously employing CDMA networks. It is also used on the Globalstar satellite phone network.
EV-DO was designed as an evolution of the CDMA2000 (IS-2000) standard that would support high data rates and could be deployed alongside a wireless carrier's voice services. An EV-DO channel has a bandwidth of 1.25 MHz, the same bandwidth size that IS-95A (IS-95) and IS-2000 (1xRTT) use. The channel structure, on the other hand, is very different. Additionally, the back-end network is entirely packet-based, and thus is not constrained by the restrictions typically present on a circuit switched network.
The EV-DO feature of CDMA2000 networks provides access to mobile devices with forward link air interface speeds of up to 2.4 Mbit/s with Rel. 0 and up to 3.1 Mbit/s with Rev. A. The reverse link rate for Rel. 0 can operate up to 153 kbit/s, while Rev. A can operate at up to 1.8 Mbit/s. It was designed to be operated end-to-end as an IP based network, and so it can support any application which can operate on such a network and bit rate constraints.
Potential competing standards
Motorola proposed a new system called 1Xtreme as an evolution of CDMA2000, but it was rejected by the 3GPP2 standardization body. Later, a competing standard called EV-DV developed by Qualcomm, Lucent, Nokia, Motorola, etc. in 3GPP2 was proposed as an alternate evolution of CDMA. EV-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. In comparison, EV-DO requires 1 or more (1.25 MHz) freq. bands in addition to the voice band. (EV-DO Rev. A could potentially support a VoIP overlay network for voice calling, but this has not been pursued except for PTT, see QChat).
At the time, there was much debate on the relative merits of DV and DO. Traditional operators with an existing voice network preferred DV, since it does not require a separate band. Other design engineers, and newer operators without a 1x voice network, preferred EV-DO because it did not have to be backward compatible, and so could explore different pilot structures, reverse link silence periods, improved control channels, etc. And the network cost was lower, since EV-DO uses an IP network and does not require a SS7 network and complex network switches such as a mobile switching center (MSC). Also, equipment was not available for EV-DV in time to meet market demands whereas the EV-DO equipment and mobile application-specific integrated circuits (ASIC) were available and tested by the time the EV-DV standard was completed. As a result, the EV-DV standard was less attractive to operators, and has not been implemented. Verizon Wireless, then Sprint Nextel in 2004 and smaller operators in 2005 announced their plans to deploy EV-DO. In March 2005, Qualcomm suspended development of EV-DV chipsets, and focused development on EV-DO.