1000BASE-T
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1000BASE-T is a standard for Gigabit Ethernet. It requires, at a minimum, Cat 5e ("Category 5 enhanced") cable. Category 6 cable may also be used. The 1000BASE-T standard was approved by the IEEE 802.3 in 1999.
In a departure from both 10BASE-T and 100BASE-TX, 1000BASE-T uses all four cable pairs for simultaneous transmission in both directions through the use of echo cancellation and a 5-level pulse amplitude modulation (PAM-5) technique. The symbol rate is identical to that of 100BASE-TX (125Ms/s) and the noise immunity of the 5-level signaling is also identical to that of the 3-level signaling in 100BASE-Tx, since 1000BASE-T uses 4-Dimensional Trellis Coded Modulation (TCM) to achieve a 6dB coding gain across the 4 pairs.