Determining Bitloading Profiles based on SNR Measurements

摘要

With the introduction of orthogonal frequency division multiplexing (OFDM) technology in to communication channels in a cable network, cable modems that receive data downstream over subcarriers of the OFDM channel are grouped in to modulation tiers based on at least one metric. A profile is generated for each OFDM channel based on the measurements across cable modems and subcarriers related to the OFDM channel, including the metric values used to group the cable modems in to the modulation tiers. Included in an OFDM profile may be a scheme for allocating marginal cable modems in to the plurality of modulation tiers. The methods and systems for generating modulation and coding scheme profiles enable more efficient modulation by network elements.

主权项

1. A method for grouping network elements based on a profile of an orthogonal frequency division multiplexed (OFDM) channel having a plurality of subcarriers, the method comprising:
dividing the OFDM channel in to a plurality of modulation tiers across the plurality of subcarriers based on a modulation level; defining a metric associated with a measurable characteristic of the network elements for each of the plurality of modulation tiers; collecting measurements for a plurality of the network elements communicating over the OFDM channel, each measurement corresponding to one of the plurality of network elements and a respective one of the plurality of subcarriers; for each of the plurality of network elements, translating the measurements collected for the respective network element in to at least one network element metric value for comparison to metric values associated with the metric defined for each of the plurality of tiers; and distributing each of the plurality of network elements to a modulation tier in the plurality of modulation tiers based on the comparison of the at least one network element metric value to the metric values associated with the metric defined for each of the plurality of modulation tiers.