ond. For a 10-gigabit system, each pair will have to carry 2.5 gigabits per second," says Kavehrad. "At these higher speeds, some energy penetrates into the other wires and produces crosstalk." The Penn State scheme eliminates crosstalk by using a new error correction method that they developed that jointly codes and decodes the signal and, in decoding, corrects the errors. "Conventional wisdom says you should deal with the wire pairs one pair at a time, but we look at them jointly," Kavehrad says. "We use the fact that we know what signal is causing the crosstalk interference because it is the strongest signal on one of the wires." The Penn State approach also accounts for the reduction or loss of signal energy between one end of the cable and the other, which can become severe in 100-meter copper systems. "We jointly code and decode the signals in an iterative fashion and, at the same time, we equalize the signals," Kavehrad says. "The new error correction approach acts like a vacuum cleaner where you first go over the rough spots and then go back again to pick up more particles." A simulation showed that the scheme is possible and can achieve an average bit error rate of 10-12 bits per second. Fiber-optic cable typically achieves 10-9 bits per second. The work is continuing. Chapter The Internet Rules IP Technologies It's hard to believe that just 10 years ago only a select group of people (mostly scientists and military leaders) was aware of the Internet. Today, it's difficult to imagine a world without Web surfing, e-mail, online chats, or (sad to say) spam. Tomorrow's Internet may still be plagued by spam in one form or another (some miseries never seem to go away), but at least data will be faster and more multimedia oriented. 5.1 VolP TELEPHONY Perhaps the biggest impact the Internet will have on telecom will come from voice-over Internet protocol (VoIP) technology. Computer-based telephony is a key technology that promises to supplement and perhaps even eventually replace conventional telephones. VoIP te