Researchers Push = Transmission Rate of Copper Cables


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Research and Academia

Researchers Push Transmission Rate of Copper = Cables

Nov. 19 -- You may not be able to get blood out of a turnip, but = according to=20 Penn State engineers, you can increase the data transmission of = Category-7=20 copper cables used to connect computers to each other and the Internet.=20

"Working with NEXANS, the company that manufactures the = cable, we=20 have examined the possibility of sending digital data at a rate of 100 = gigabits=20 per second over 100 meters of Category-7 copper cable," says Mohsen = Kavehrad,=20 the W.L. Weiss Endowed Chair professor of electrical engineering. "These = are the=20 current, new generation of Ethernet cables."

These cables are used to connect computers within a room or a = building or to=20 create parallel computing systems.

While the long distance lines of most Internet systems are glass = fiber optic=20 cables, which are very fast, copper cable is generally used for short = distances.=20

"In home networks, for example, it is expensive to use fiber optic = cabling,"=20 says Ali Enteshari, graduate student in electrical engineering who = presented the=20 team's methods to the IEEE High Speed Study Group today (Nov. 14) in = Atlanta.=20

All transmission cables are limited by the distance they can transmit = data=20 without degradation of the signal. Before errors and interference make = the=20 signals non-recoverable, cable systems use repeaters -- which are = similar to=20 computer modems -- to capture, correct or recover data, and resend it. = The=20 distance between repeaters depends on the cable and the approach used by = the=20 modem to correct errors.

"What we are offering is a less expensive solution and one that is = easier to=20 build," says Jarir Fadlullah, graduate student in electrical = engineering.

Using information on specifications and characteristics of the cables = from=20 NEXANS, the researchers modeled the cable with all its attributes = including=20 modeling crosstalk. They then designed a transmitter/receiver equipped = with an=20 interference canceller that could transfer up to 100 gigabits using = error=20 correcting and equalizing approaches. Ethernet cable like the Category 7 = is made=20 up of four pairs of twisted wires shielded to reduce crosstalk. Category = 7 is=20 heavier weight wire with better shielding than Category 5 cable. = Kavehrad's=20 group did similar analysis on the Category 5 cables in 2003.

"A rate of 100 gigabit over 70 meters is definitely possible, and we = are=20 working on extending that to 100 meters, or about 328 feet," says = Enteshari.=20 "However, the design of a 100 gigabit modem might not be physically = realizable=20 at this time as it is technology limited. We are providing a roadmap to = design a=20 high speed modem for 100 gigabits."

The researchers believe that two or three generations in the future, = the=20 technology of chip circuitry will allow these modem designs to be built. = Currently, chip design is at about 65 nanometers, but they expect in the = next=20 two generations to get to what is required, says Kavehrad.

The amount of data encompassed by 100 gigabits is amazing. The entire = Encyclopedia Britannica contains 1 gigabyte of information. A byte is = equivalent=20 to 8 bits, so 1 Gigabyte is equal to 8 gigabits. A rate of 100 gigabits = per=20 second over 100 meters is the transmission of 12.5 Encyclopedia = Britannica sets=20 per second.

-----

Source: Penn State

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