100BASE-T2 - A NEW STANDARD FOR 100 MB S ETHERNET TRANSMISSION OVER VOICE-GRADE CABLES/

100BASE-T2 is a new physical-layer specification for IEEE 802.3 LANs o perating at 100 Mb/s (''Fast Ethernet''). It enables users of the prev ailing 10BASE-T Ethernet LAN technology to upgrade their networks from 10 to 100 Mb/s performance while retaining an existing voice-grade ca bling infrastructure. 100BASE-T2 transceivers will operate over two pa irs in unshielded twisted-pair cables corresponding to EIA/TIA categor y 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. Since voice-grade cables exhib it more signal attenuation and significantly higher crosstalk coupling between adjacent pairs than data-grade cables, sophisticated digital signal processing techniques are needed to achieve reliable duplex 100 Mb/s transmission over two pairs. The 100BASE-T2 standard defines dua l-duplex baseband transmission at a modulation rate of 25 Mbaud. Durin g each modulation interval, a four-bit data nibble or Ethernet-specifi c control information is encoded into a pair of quinary signals. These signals are transmitted simultaneously on the two wire pairs in both signaling directions. in the receivers, adaptive digital filters are r equired for echo and NEXT cancellation, equalization, and interference suppression.