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100BASE-T2 is a new physical layer specification for IEEE 802.3 LANs operating at 100 Mbit/s (Fast Ethernet). It enables users of the prevailing 10BASE-T Ethernet LAN technology to upgrade their networks from 10 to 100 Mbit/s performance while retaining an existing voice-grade cabling infrastructure. 100BASE-T2 transceivers will operate over two pairs in unshielded twisted pair cables corresponding to EIA/TIA category 3 (UTP-3), as minimally required for 10BASE-T. In a four-pair UTP-3 cable, simultaneous operation of two 100BASE-T2 links, or one 100BASE-T2 and one 10BASE-T link, is permitted. As voice-grade cables exhibit more signal attention and significantly higher crosstalk coupling between adjacent paris than data-grade cables, sophisticated digital signal processing techniques are needed to achieve reliable 100 Mbit/s transmission. The 100BASE-T2 standard defines dual-duplex baseband transmission at a modulation rate of 25 MBaud. During each modulation interval, a four-bit data nibble or Ethernet-specific control information is encoded into a pair of quinary signals. These signals are transmitted simultaneously on the two wire pairs in both signalling directions. In the recievers, adaptive digital filters are required for echo and NEXT cancellation, equalization and interference suppression.
By: Giovanni Cherubini, John Creigh (IBM Research Triangle Park), Sedat Olcer, Sailesh K. Rao (Silicon Design Experts, Inc.) and Gottfired Ungerboeck
Published in: IEEE Communications Magazine, volume 35, (no 11), pages 115-22 in 1997
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