LINE CODE SELECTION FOR 155.52 MB S DATA-TRANSMISSION ON CATEGORY-5 CABLE PLANT/

EMV/EMC is a dominant problem encountered in high bit-rate (>100 Mb/s) transmission over unshielded twisted-pair cable (UTP) which leads to a novel set of line-code dependent tradeoffs affecting transceiver and cable plant complexity. To understand the tradeoffs, we examined the factors affecting RF emissions and susceptability in both trellis-conf igured cable plant models and installed cable plant. An analytical mod el is presented that describes mode conversion by discontinuities in m ulti-pair UTP cable plant. Termination of the three dominant propagati ng modes produces consistently lower radiated emissions than other sta ndard cable termination procedures. Cable plant parameters which predi ct good transmission do not assure satisfactory EMI performance. Radia ted emissions from the trellis model occur in broad bands at 43, 53, 6 0, 70, and 80 MHz, and show a positive correlation with the transmit s ignal spectrum. For a given transmit level at 155 Mb/s, the emissions with MLTS and BPR1 were 8-13 dB (10 dB typ) and 4-20 dB (13 dB typ) be low NRZ levels, respectively. We also compared the performance of NRZ, MLT3, BPR1, and BPR4 line codes in an experimental 155 Mb/s link with 100 m of UTP5 by measuring the BER sensitivity to both injected noise and pseudo-random data sequence length. When the measured receiver pe nalty associated with three levels is included, MLT3, BPR1, and BPR4 o ffer 5-15 dB better performance over NRZ at 155 Mb/s, although impleme ntation complexity is greater.