100 Mb/s data transmission on UTP and STP cabling for demand priority networks

There have been considerable advances towards higher speed (100 Mb/s) workgroup LANs which support the existing UTP and STP structured cabling utilized by 10 BASE-T and token ring LANs. The paper describes the transmission techniques used by an IEEE 802.12 demand priority network with UTP and STP structured cabling. The UTP transmission scheme supports categories 3-5 UTP (i.e. voice-grade and data-grade) using a 5B6B block coded binary signalling scheme on four pairs. This binary signalling scheme is shown to provide better immunity against crosstalk and external (impulse) noise than multilevel signalling schemes. The STP scheme combines the strengths of the 5B6B block code with signalling technology similar to existing SDDI links.