Patent ID: 6333920
Filing Date: 2001-12-25
Classification: H04L,H04M

Abstract:
A frequency division duplexing telecommunications system which provides very high speed digital subscriber line symmetric and asymmetric services to a plurality of subscribers connected to said system by local subscriber loops comprising varying lengths of two wire pairs thereby defining local subscriber loops of varying reach, said system comprising:an upstream transmitter which transmits over the local subscriber loops within a relatively low frequency upstream channel, anda downstream transmitter which transmits within a downstream channel that is a higher frequency channel than said relatively low frequency upstream channel, wherein said frequency channels are separated by a guard band, the upstream and downstream channels are varied with the reach of a particular subscriber local loop, and the guard band varies along with the upstream and downstream channels, with the lowest frequency of the upstream channel remaining substantially the same while the lowest frequency of the downstream channel shifts to a lower frequency as the reach of the particular subscriber loop increases.