Streamyx Info

By Saul Hansell

There is a constant refrain that the United States is falling behind in broadband, as if the speed of Internet service in Seoul represents a new Sputnik that is a challenge to national security.

It’s certainly true that in some countries, like South Korea, far more homes have broadband connections than in the United States. And the speeds in some countries are far higher than is typical here.

But there are many ways to measure the bandwidth wealth of nations. At the Columbia/Georgetown seminar on the broadband stimulus yesterday, I heard Leonard Waverman, the dean of the Haskayne School of Business at the University of Calgary, describe a measure he developed called the “Connectivity Scorecard.” It’s meant to compare countries on the extent that consumers, businesses and government put communication technology to economically productive use.
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3G(Third Generation Mobile Telephony)
3G is an ITU(International Telecommunication Union) specification for the third generation (analog cellular was the first generation, digital PCS the second) of mobile communications technology.3G promises increased bandwidth up to 384 Kbps when a device is stationary or moving at pedestrian speed, 128 Kbps in a car, and 2 Mbps in fixed applications. Implemented in Europe as UMTS and CDMA2000 in North America, its goals are high-quality multimedia and advanced global roaming.

WCDMA(Wideband Code Division Multiple Access)
A 3G technology that increases data transmission rates in GSM systems by using the CDMA air interface instead of TDMA. WCDMA is based on CDMA and is the technology used in UMTS. WCDMA was adopted as a standard by the ITU under the name “IMT-2000 direct spread”. It has been selected for the third generation of mobile telephone systems in Europe, Japan and the United States.

UMTS(Universal Mobile Telecommunications System)
Third generation telecommunications system based on WCDMA-DS. The goal of UMTS is to enable networks that offer true global roaming and can support a wide range of voice, data and multimedia services. A new-generation technology for rapidly moving data and multimedia over wireless devices. The European implementation of the 3G wireless phone system, UMTS provides service in the 2GHz band and offers global roaming and personalized features; designed as an evolutionary system for GSM network operators, multimedia data rates offered by UMTS are: vehicular - 144 kbit/s; pedestrian 384 kbit/s; in-building 2Mb/s.

HSDPA(High-Speed DownlinkPacket Access)
HSDPA is a packet-based data service in WCDMA downlink with data transmission up to 8-10 Mbps (and 20 Mbps for MIMO systems) over a 5MHz bandwidth in WCDMA downlink. The high speeds of HSDPA are achieved through techniques including: 16 Quadrature Amplitude Modulation, variable error coding, and incremental redundancy.

ATM(Asynchronous Transfer Mode)
A network technology protocol based on encoding and transmitting data in relatively small cells/packets of a fixed length. Allows for high-speed transmission of video, audio and data over the same network.

ATM is a connection-oriented switching technique with very high speed and high bandwidth. The CCITT (Consultative Committee International Telephone and Telegraph) is betting on ATM’s many benefits for the future broadband network.

In general, broadband refers to telecommunication in which a wide band of frequencies is available to transmit information. Because a wide band of frequencies is available, information can be multiplexed and sent on many different frequencies or channels within the band concurrently, allowing more information to be transmitted in a given amount of time (much as more lanes on a highway allow more cars to travel on it at the same time). Related terms are wideband (a synonym), baseband (a one-channel band), and narrowband (sometimes meaning just wide enough to carry voice, or simply “not broadband,” and sometimes meaning specifically between 50 cps and 64 Kpbs).

Various definers of broadband have assigned a minimum data rate to the term. Here are a few:

Newton’s Telecom Dictionary: “…greater than a voice grade line of 3 KHz…some say [it should be at least] 20 KHz.”
Jupiter Communications: at least 256 Kbps.
IBM Dictionary of Computing: A broadband channel is “6 MHz wide.”
It is generally agreed that Digital Subscriber Line (DSL) and cable TV are broadband services in the downstream direction.

WHAT IS BANDWITH
1) In electronic communication, bandwidth is the width of the range (or band) of frequencies that an electronic signal uses on a given transmission medium. In this usage, bandwidth is expressed in terms of the difference between the highest-frequency signal component and the lowest-frequency signal component. Since the frequency of a signal is measured in hertz (the number of cycles of change per second), a given bandwidth is the difference in hertz between the highest frequency the signal uses and the lowest frequency it uses. A typical voice signal has a bandwidth of approximately three kilohertz (3 kHz); an analog television (TV) broadcast video signal has a bandwidth of six megahertz (6 MHz) — some 2,000 times as wide as the voice signal.

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