Dean E. Wolf, Esq. Beyer Weaver & Thomas, LLP
Method and apparatus for upstream frequency channel transition
Transitions among different upstream frequency channels in a cable television plant in order to transmit data occur while considering the noise level of the upstream frequency channel presently being used to transmit data. By taking into account the noise level of the presently used upstream frequency channel, the CMTS in a cable plant can make a more intelligent decision as to whether it is worthwhile changing the upstream frequency channel for a group of cable modems. A spectrum analyzer determines the noise level of a presently used frequency channel. A bit error rate for the present frequency channel is detected. The spectrum analyzer then determines whether the bit error rate exceeds a threshold value. Is so, it is then determined whether the noise level of the present frequency channel is greater than or less than the noise level of another frequency channel having the lowest noise level plus a buffer noise value. If the present noise level is greater, a transition is made to the other frequency channel with the lower noise level. If not, the cable plant continues using the present frequency channel. The noise level of the presently used frequency channel is measured at the CMTS upon receipt of an empty data packet arriving at a known timing mark.
Cisco Techology, Inc.
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inventional inventional
Wei-Sing Charles J. Mark E. Alejandro H. Hung-San
Chen Naegeli Millet Schwartzman Chen