Evolution Data Optimized (EV-DO) - Online Article


Evolution-data optimized (EV-DO) is next step for the code division multiple access (CDMA) networks moving towards 3G. EV-DO Rev 0 promises data speeds up to 2.4 Mbps on the forward link and 153.6 kbps on the download link. Compare this with the shared 64 kbps, where a subscriber actually gets between 20–35 kbps over GPRS connectivity, and the 140–150 kbps over EDGE networks. Even the offered speed of 300–400 kbps over EV-DO is faster than any other wireless access technology.

In January 2005, there were about 125 commercial 3G operators in 56 countries, with almost 10.8 million EV-DO subscribers globally. In India, CDMA operators Reliance Infocomm and Tata Indicom have expressed their intention to launch EV-DO. In fact, Reliance has been conducting pilots at the Reliance Knowledge Center and its officials said as soon as additional spectrum is granted the services would be available throughout India.

EVDO, also known as EV-DO, 1xEvDO and 1xEV-DO, is a standard for high speed wireless broadband. The acronym is short for "Evolution, Data Only" or "Evolution, Data Optimized". The official name, defined by the Telecommunication Industry Association, is "CDMA2000, High Rate Packet Data Air Interface". It is one of two major Third Generation, or 3G, wireless standards. The competing standard is known as W-CDMA.

3G is designed to provide voice and high-speed mobile data using the cellular approach already proven to work in mobile phone networks. The biggest obstacle to implementing high speed wireless networks is the lack of bandwidth, or range of usable frequencies. Just as only so many radio stations can be squeezed onto the FM dial, only so much data can be transmitted across the available bandwidth. EVDO is an advanced CDMA technology developed by Qualcomm to deal with this limitation.

CDMA, Code Division Multiple Access, uses advanced mathematical techniques to allow multiple wireless devices to transmit simultaneously on the same frequency. Every device, such as a cell phone, is assigned a unique mathematical signature. It applies this signature to the original signal and transmits the modified signal. A receiver applies the inverse of the mathematical operation to recover the original signal.

Traditional wireless networks create a physical path between receiving and sending devices, much like traditional telephone networks. EVDO instead adopts the same approach used for the internet. IP, the Internet Protocol, breaks data into small pieces called packets. Each packet is sent independently of all the other packets. This saves bandwidth for use by other devices; when neither party on a phone call is speaking, the connection consumes no bandwidth because there are no packets to send. Or, when an internet web site is accessed, no bandwidth is used until the site starts sending the web page.

EVDO has a theoretical throughput of 2.4 megabits per second. This is as fast as many residential DSL and cable broadband connections currently available in the United States. Qualcomm has produced impressive demonstrations of EVDO's capabilities; in one, a video conference was conducted with a participant traveling in a car at 60 miles per hour (96 km/hour). In another demonstration, a phone call was placed from a bullet train moving in excess of 150 miles per hour (240 km/hour).

A significant advantage of EVDO over competing technologies is that it uses the same broadcasting frequencies as existing CDMA networks. As purchasing spectrum from regulatory agencies is extremely expensive, this brings down the cost of building and using the new networks. The major EVDO deployments in the US are by Verizon and Sprint, and there is also a large network in Korea. At present, EVDO has not made significant impact in Europe or other major Asian markets; W-CDMA is the 3G standard of choice in those regions.

How Does EV-DO Work?

EV-DO is part of the CDMA2000 family and hence the operators do not require any major addition or changes in the network architecture. At the user end, an EV-DO-enabled device (a laptop with a PC card, PDA, or phone) is required.

The current CDMA2000 1x supports both voice and data on the 1.25 MHz carrier.The 1x EV is optimized to carry only data traffic in single 1.25 MHz carrier.

Making Business Sense

In the 5MHz spectrum, 1x EV can deliver up to 3.2 Mbps. CDMA2000 1x and WCDMA give 1.1 Mbps and GPRS 80 kbps respectively. As the capacity of a network is limited, the cost to deliver one megabyte for 1x EV is $0.02 for CDMA2000 1x, for WCDMA it is $0.07, and GPRS comes to $0.42.

With IP being the key, and data usage poised to grow, everyone is betting their money on EV-DO. A Qualcomm study indicates data volumes of more than 200 Mb per user per month by 2006 over the wireless networks. This makes a perfect case for better networks, applications, and mobile access devices to support high volumes of data at higher throughput.

In the migration to EV-DO, CDMA networks will require very little tweaking compared to migrating GPRS-enabled networks to WCDMA.

With BREW being promoted by Qualcomm for multimedia applications and the company putting money in MediaFlo to push in multimedia services, CDMA operators stand to gain from the EV-DO environment.

EV-DO would essentially give the user broadband access while on the move, not just wireless but a really mobile, high-speed access. Instead of getting tied to a hotspot coverage area, EV-Do would ride wherever the operator has network.

While the deployment of EV-DO Rev 0 is still in its nascent stages, vendors are already contemplating Rev A with speeds of over 3.1 Mbps. EV-DO Rev A would further enhance the data-carrying capacity and operators would be able to offer commercial-grade VoIP and other packet switched applications over wireless networks.


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