Wireless Data Technologies

Wireless Data 101

GSM/GPRS

(General Packet Radio Service)

GPRS is a packet-switched service that allows data communications to be sent and received over the existing Global System for Mobile (GSM) communications network. This allows the user of a computing device with a GPRS modem to connect to the Internet and exchange data with servers and web sites for mobile access to e-mail, corporate databases, and browsing the web. With GPRS, the user will experience data rates significantly faster than a GSM circuit switched data connection. The initial user experience is expected to have a peak data rate of 53.6kbps for downloading data.

The GSM network, upon which GPRS is built, has more coverage than any other cellular technology.

GPRS data transmission is analogous to a jigsaw puzzle. On the mobile device, Internet (TCP/IP) data is broken down into small pieces. When the data is ready to be sent, the network assigns timeslots on a channel for the transmission. From the mobile device, the pieces are then sent over the air to the cellular base-station, reassembled into TCP/IP data, and then passed to the Internet for transport to the destination.

A GSM channel contains eight timeslots, normally each timeslot is dedicated to one circuit switched call. For GPRS the timeslots are assigned on an as needed basis, and more than one timeslot can be assigned for a particular transmission depending on the network and the device. By using multiple time slots a user will experience data rates that would not be possible with a GSM circuit switched connection. The resulting baud rate is dependent on the number of slots utilized and the error-correction and encryption overhead.

The network operator gains the efficiency of packet data. Most applications only need to send or receive data for short periods of time. By using the airwave resource on an as needed basis rather than a dedicated circuit for one user at a time, many users may share a set of timeslots. This results in more efficient usage of the radio frequency. The cost is based on the amount of data sent and received, not on the length of the user's session. The user, therefore, is able to stay connected all day, and is charged fairly for their use of the network.

GPRS supports a wide spectrum of possible applications that are crucial to the success of the mobile user, reliable two-way access to email, corporate databases and all the services of the Internet. In addition, mobile communication features such as fax, SMS, circuit switched data and voice are available with a GPRS modem, offering an improvement to the way business is done. GPRS wireless data has applications in mobile computing, handheld game devices, POS terminals, vending machines, remote instrumentation and control systems, vehicle information and tracking, security, and limitless other possibilities.

U.S. Carriers include:

Cingular Wireless

EDGE

(Enhanced Data for Global Evolution)

Further enhancements in data capability over the core GSM network will be provided with the introduction of Enhanced Data rates for GSM Evolution - known as EDGE*. This will achieve the delivery of advanced mobile services such as the downloading of video and music clips, full multimedia messaging, high-speed color Internet access and e-mail on the move.

EDGE (or Enhanced Data Rates for Global Evolution) is a 3G technology that delivers broadband-like data speeds to mobile devices. It allows consumers to connect to the Internet and send and receive data, including digital images, web pages and photographs, three times faster than possible with an ordinary GSM/GPRS network. EDGE enables GSM operators to offer higher-speed mobile-data access, serve more mobile-data customers, and free up GSM network capacity to accommodate additional voice traffic.

U.S. Carriers include:

Cingular Wireless

CDMA

(Code Division Multiple Access)

CDMA is a digital wireless technology and cellular telephone standard developed by Qualcomm. CDMA differs from other cellular wireless technologies in the way information is transmitted over the air. CDMA uses unique coding for each call or data session, which allows your mobile device to disregard other transmissions on the same frequency. In effect CDMA lets everybody in the area use the same piece of spectrum, and separates the calls by encoding each one uniquely. CDMA data transmission is analogous to an international cocktail party-dozens of people are in the room, all talking at once, and all talking in different languages that you don't understand. Suddenly, from across the room, you hear a voice speaking in your own familiar language, and your brain tunes out all the background gibberish and locks onto to that one person. Your brain understands the "code" being used by the other person, and vice versa.

CDMA was commercially introduced in 1995 with the IS-95A Standard, which is currently used by millions of cellular voice subscribers. CDMA / IS-95A is a second generation (2G) wireless standard. The Third Generation of mobile communications (3G) is a concept outlined in a set of proposals called International Mobile Telecommunications-2000 (IMT2000), to define an "anywhere, any time" standard for the future of universal personal communications. In 1999, the CDMA2000 series of standards were introduced as the path for CDMA to evolve into a 3G wireless network. The CDMA path to 3G is through CDMA2000 1X, then onto CDMA2000 1xEV-DO and 1xEV-DV.

The CDMA2000 network upgrades being commercialized in North America in 2002 is the CDMA2000 1X standard. CDMA2000 1X supports high speed packet data services and allows data and voice communications to be sent and received over the existing CDMA communications network. CDMA2000 1X provides a maximum over-the-air data rate of 153.6kbps, which is up to sixteen times that of a CDMA IS-95A circuit-switched connection, and provides the efficiency of packet data so that more users can be connected simultaneously. Currently, the average throughput speed on the CDMA2000 1X network is between 40-70 kbps.

CDMA2000 1X enables operators with existing IS-95A systems to double overall system capacity, and increase data rates to as much as 614kbps. The first implementation of CDMA2000 1X is expected to yield data rates up to 153.6 kbps. Most applications like email or short messaging only need to send or receive data for short periods of time. By using the airwave resource on an as-packets-are-needed basis rather than a dedicated circuit for one user at a time, many users may share a space with coded packets within the channel.

This results in more efficient usage of the radio frequency, in addition to the fast peak data rates. Actual pricing plans for data usage may vary from operator to operator; however, it is anticipated that the cost for data will be based on the amount of data sent and received, not on the length of the user's session.

For the customer, CDMA2000 1X offers applications crucial for the mobile professional: Reliable high speed, two-way access to email, corporate databases and all the services of the Internet. Short Messaging Service (SMS), fax, location based services and voice are also supported.

The customer is always connected, always on-line. This means that information can be sent or received as needed, there is no delay for establishing a dial up modem connection. This always on performance is critical for mobile users to efficiently use the Internet. The customer's privacy is assured as the CDMA network is secure. The data bits used to convey real information are mixed with digital coding that is known only to the base station and the mobile terminal. To an eavesdropper the data looks like unintelligible noise.

U.S. Carriers include:

Sprint PCS and Verizon Wireless

EVDO

(Evolution-Data Optimized)

Evolution Data Only, Evolution Data Optimized, often abbreviated as EVDO, EV-DO, EvDO, 1xEV-DO or 1xEvDO is a wireless radio broadband data protocol being adopted by many CDMA mobile phone providers in Japan, Korea, the United States and Canada, as part of the CDMA2000 standard. In comparison to the 1xRTT networks being used by these carriers currently or the GPRS and EDGE networks being employed by their GSM competitors, EV-DO is significantly faster, allowing clients download speeds of up to 2.4 mbit/s. Only phones that are enabled for EVDO can take advantage of the higher speeds. With the high speeds projected for this network, this protocol could enable the ideal 3G spec envisioned by FCC regulations, allowing high speed video transmission.

EV-DO is the first stage of the CDMA2000 standard. The next stage will be EV-DV or Evolution Data and Voice.

U.S. Carriers include:

Verizon Wireless