Tutorial – cdma2000 Technology Family: 1xRTT, EVDO, UMB, and EVDV


It is a third-generation (3G) wireless technology, based on Code Division Multiple Access (CDMA), that has evolved from cdmaOne (or IS95), a 2G technology. By contrast, UMTS is also a CDMA-based 3G technology that represents an evolutionary step forward for the 2G GSM networks. Please note that while cdmaOne was a CDMA-based system, GSM is a Time Division Multiple Access (TDMA) system.

The name cdma2000 actually denotes a family of standards that represent the successive, evolutionary stages of the underlying technology. These are, in order of evolution:

  • CDMA2000 1xRTT
  • CDMA2000 1xEV-DO: Release 0, Revision A, Revision B
  • CDMA2000 1xEV-DO Revision C or Ultra Mobile Broadband (UMB)
  • CDMA2000 1xEVDV

In the above nomenclature, EVDO is short for Evolution – Data Optimized and EVDV, for Evolution – Data and Voice.

History and Standards

The cdma2000 family of standards, developed by the Third Generation Partnership Project 2 (3GPP2), was intended to be deployed in several evolutionary phases:

  • The cdma2000 1xRTT technology, also called 1xRTT , 1x, cdma20001x, or simply cdma2000, was recognized by the International Telecommunications Union (ITU) as an IMT-2000 standard in November 1999 and given the numeric designation of IS-2000. It was the first IMT-2000 technology deployed worldwide, in October 2000.
  • 1xEV-DO, also called EV-DO, EVDO, or just EV, was initially developed by Qualcomm in 1999 to meet the IMT-2000 requirements for a greater-than-2-Mbit/s downlink for stationary communications. For a while, the standard was called HDR (High Data Rate) but was renamed as 1xEV-DO after it was ratified by the ITU and given the numerical designation of IS-856. Originally, 1xEV-DO stood for “1x Evolution-Data Only”, referring to its being the next evolutionary step after the 1xRTT (“1x”) standard, with its channels carrying only data traffic. Later, due to the negative connotations of the word “only” in its name, the “DO” part of EV-DO was changed to represent “Data Optimized”. So EV-DO now stands for “Evolution-Data Optimized”. Many carriers drop the 1x prefix and market this technology simply as EV-DO or EVDO. EVDO has been adopted by many service providers in the United States, Canada, Mexico, Europe, Asia, Russia, Brazil, and Australia.
  • The UMB standard is currently under development by the 3GPP2 with its publication scheduled for April 2007 with commercial availability expected in early 2009.
  • 1xEV-DV for Evolution – Data and Voice, supports downlink data rates up to 3.1 Mb/s and uplink data rates of up to 1.8 Mb/s. EV-DV can also support concurrent operation of legacy 1x voice users, 1x data users, and high speed EV-DV data users within the same radio channel. In 2005, Qualcomm put the development of EV-DV on an indefinite halt, since both Verizon Wireless and Sprint, major cdma2000 carriers, are using EV-DO

Evolution of cdmaOne to cdma2000 1xRTT

The 1x designation in the technology’s name indicates a carrier spreading factor of approximately 1.25 MHz. The following characteristics of 1x are derived from its CDMA roots and make it backward compatible with cdmaOne:

  • Direct Sequence Spread Spectrum (DSSS) Multiple Access: To improve spectral efficiency (system capacity)
  • Orthogonal Code Channelization: For user separation on the downlink (mitigates interference)
  • Random Access: To efficiently share radio access resources among all users
  • Fast Uplink Power Control: To resolve the near-far field effect (reduces interference)
  • Rake Receivers: To resolve and benefit from multipath interference and support soft handoffs
  • Soft Handoff: To hand off users between base stations
  • Softer Handoff : To hand off users between base station sectors
  • Soft Handoff (SHO) Active Set: To provide seamless service with increased spectral efficiency
  • Single Frequency Reuse: To increase overall network capacity
  • Downlink Slotted Paging: To extend the battery life of mobile devices
  • Blind Rate Detection: To enable variable rate decoding without additional overhead
  • Downlink Reference Channel: To share a common pilot to increase capacity
  • Downlink Channel Structure: Tosimplify system implementation and efficiency by separating channels with Walsh codes
  • Scrambling: To provide communications privacy
  • Speech Regulated Vocoders: Toreduce interference and increase system capacity

The cdma2000 1x technology is the most spectrally efficient wide area network technology for circuit-switched voice communications and it supports packet data speeds of up to 307 kbps in a single 1.25 MHz channel. Key features of 1x include:

  • Voice Capacity: Supports 33-35 up to 40 simultaneous voice calls per single 1.25 MHz FDD channel. A new codec, 4GV, for CDMA2000 1X will increase voice capacity by 40%.
  • High-Speed Data: Release 0 supports bi-directional peak data rates of up to 153 kbps and an average of 60-100 kbps in commercial networks in a 1.25 MHz channel. Release 1 can deliver peak data rates of up to 307 kbps.
  • Applications: Supports circuit-switched voice, short messaging service (SMS), multimedia messaging service (MMS), games, GPS-based location services, music and video downloads.


Next Step Up: cdma2000 1xEV-DO

Revision 0: EV-DO Rev 0 was the original version of 1xEV-DO and the first to be widely deployed. Revision 0 offered data rates up to 2.4 mbps, averaging 300-600 kbps in the real world. This is much faster than the 50-80 kbps typically offered by 1xRTT technology. Other key features introduced by Revision 0 include:

  • Leverages the existing suite of Internet Protocols (IP) and hence supports IP-based network connectivity and software applications
  • Supports broadband data applications, such as broadband Internet or VPN access, MP3 music downloads, 3D gaming, TV broadcasts, video and audio downloads. In many countries, it has been deployed as a DSL substitute.

Revision A: EV-DO 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 an increase in the maximum downlink rate from 2.45 Mb/s to 3.1 Mb/s, Rev. A incorporates 12 time improvement in the maximum uplink data rate, from 225 Kb/s to 1.8 Mb/s. EV-DO Rev. A supports low latency services (as low as 50ms) including VoIP and video telephony on the same carrier with traditional Internet packet data services. EV-DO Rev. A air-interface latency specifications have not been published, however several Qualcomm documents note latency in the “low double digit” range with the highest RSVP settings. Latency of 50ms is claimed to be possible. This compares favorably with Rev. 0 latencies of 150-200 ms.

Revision B: EV-DO Rev B is the next evolutionary step up from EV-DO Rev A. It adds the following enhancements:

  • Higher rates per carrier (up to 4.9 Mbps on the downlink).
  • Higher rates by bundling multiple channels together enhance user experience and enables new services such as high definition video streaming.
  • Utilizes statistical multiplexing across channels to further reduce latency, enhancing the experience for latency-sensitive services such as gaming, video telephony, remote console sessions and web browsing.
  • Hybrid frequency reuse which reduces interference from the adjacent sectors and improves the rates that can be offered, especially to users at the edge of the cell.

Ultra Mobile Broadband: cdma2000 Rev. C

Ultra Mobile Broadband (UMB) is a breakthrough technology which will support the ITU’s vision for next generation services. It combines the best aspects of CDMA, TDM, LS-OFDM, OFDM, and OFDMA into a single air interface using advanced and highly optimized control and signaling mechanisms. It also incorporates advanced antenna techniques such as MIMO and SDMA. The combination of these techniques enables UMB to achieve higher peak data rates, very low latency, and very high spectral efficiency. The technology has a flexible and dynamic mode of operation to combine and allocate spectrum as needed for the variety of user applications and activities.

The key features of this technology include:

  • Multiple radio and advanced antenna techniques: Sophisticated control and signaling mechanisms (minimized) combine the best aspects of CDMA, TDM, OFDM, and OFDMA into a single air interface; Multiple Input Multiple Output (MIMO) and Space Division Multiple Access (SDMA); improved interference management techniques
  • Ultra-high mobile broadband peak data rates: Up to 280Mbps peak data rate on forward link; up to 68Mbps peak data rate on reverse link
  • Ultra-low network latency: An average of 16.8 msec (32-byte, RTT) end-to-end network latency
  • Enhanced VoIP capacity and user experience: Up to 500 simultaneous VoIP users (10 MHz FDD allocations)
  • Scalable IP-based flat or hierarchical architecture: Greater service deployment flexibility, improved performance, and lower cost of ownership
  • Flexible spectrum allocations: Scalable, non-contiguous and dynamic channel (bandwidth) allocations; support for bandwidth allocations up to 20 MHz in 1.25 MHz blocks
  • Lower power consumption: Improved battery life

Strengths and Weaknesses of cdma2000 and Comparison with Other Technologies

The primary attributes of CDMA as a multiple access technology for cellular applications are as follows:

  • CDMA systems have proven to be cost effective requiring fewer cell sites and no costly frequency reuse pattern within the network.
  • CDMA allows the largest number of subscribers to share the same radio frequencies.
  • CDMA uses spread spectrum technology which can provide up to 10-20 times the capacity of analog equipment and more than three times the capacity of other digital platforms.

To those inherent CDMA characteristics, cdma2000 adds the following performance advantages:

  • Superior voice clarity
  • High-speed broadband data connectivity
  • Low end-to-end latency
  • Increased voice and data throughput capacity
  • Time-to-market performance advantage
  • Long-term, robust and evolutionary migration path with forward and backward compatibility
  • Differentiated value-added services such as VoIP, push-to-talk (PTT), multicasting, position location, etc.
  • Application, user and flow-based quality of service (QoS)
  • Flexible spectrum allocations with excellent propagation characteristics
  • Robust link budget for extended coverage and increased data throughputs at the cell edge
  • Multi-mode, multi-band, global roaming
  • Improved security and privacy
  • Lower total cost of ownership (TCO)

Business Implications and Market Landscape

The U.S. business implications for cdma2000 and the subsequent upgrades of 1x EVDO can be compared with the competitive 3G wireless technologies using the following four key market indicators.

  • Subscriber growth
  • Network coverage
  • Availability of handsets
  • Cost of handsets to the consumer

Global Subscriber growth in 2006: CDMA2000 and 1x EV-DO upgrades gained additional customers in 2006:
There were 301,900,000 cdma2000 subscribers (3Q) and 45,080,000 1xEV-DO subscribers in the world at the end of 3Q 2006. At the end of 2006, more than 8.5 million new customers subscribed to cdma2000 services every month. During the same period (3Q-2006), there were 81.2 million UMTS subscribers worldwide.

U.S network coverage: Verizon and Sprint Nextel are the leading cdma2000 carriers in terms of national coverage. (The latter also operates an iDEN network under the Nextel brand.) While Cingular, a GSM/UMTS carrier has only covered 52 major markets in 28 states (just over 50% of the market) thus far, both Verizon and Sprint are nearing complete nation-wide coverage.

Availability of handsets: In the critical area of handsets, EV-DO is the leader. As of Sept 2006, there were 31 3G handsets available in the market. Twenty six of those handsets were for EV-DO (15 from Verizon and 11 from Sprint Nextel) versus only five UMTS/HSDPA handsets from Cingular.

Cost of handsets: The average price of a 3G handsets in the U.S. is approximately $140 for low-end phones and $250 on the high-end. Sprint Nextel and Verizon are already testing and introducing Rev. A devices. EV-DO Rev B and Rev C are likely to be introduced in 2008 and 2009, respectively

Worldwide market growth for all wireless 3G technologies: At the end of 3Q 2006, there were 2.53 billion cellular subscribers worldwide. The 3G market share of the total world market includes 301.9 million cdma2000 subscribers and 81.2 million UMTS subscribers. Approximately 2.1 billion remaining subscribers are GSM/UMTS/EDGE (non 3G) users.

How to Learn More about cdma2000


  • If you are interested in learning more about the cdma2000 technology family, check out our CDMA2000/CDMA Curriculum.
  • If your work requires an understanding of the broader technology landscape (along with a knowledge of CDMA2000/CDMA),  you should consider taking our All Wireless course.


Web Resources

  • 3GPP2 is the cdma2000 standards development project: http://www.3gpp2.org/
  • CDG is a trade group that includes CDMA carriers, equipment vendors, application developers, and content providers: http://www.cdg.org/