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US-12627421-B2 - Adaptive aggregation of metrics for OFDM/OFDMA profile generation

US12627421B2US 12627421 B2US12627421 B2US 12627421B2US-12627421-B2

Abstract

Devices, systems and methods for adaptively associating a percentile value to each of a plurality of subcarriers at which a cable modem communicates data, the percentiles value used to respectively determine an aggregated RxMER value for each subcarrier. The aggregated RxMER values for the subcarriers may be used to determine and assign one or more bitloading profiles to the cable modem.

Inventors

  • Santhana Chari
  • David Emery Virag
  • Janaki SAJJA
  • Deepak Garageswari Jagannath RAO

Assignees

  • ARRIS ENTERPRISES LLC

Dates

Publication Date
20260512
Application Date
20230601

Claims (15)

  1. 1 . A method for allocating bitloading profiles to a cable modem, the method comprising: receiving error data for the cable modem spanning a plurality of subcarriers; selecting a range of subcarriers; determining a percentile value based on an analysis of the error data in the selected range; using the percentile value to determine an aggregated error metric; associating the aggregated error metric with each subcarrier in the selected range; determining a plurality of bitloading profiles based on the association of the aggregated error metric with each subcarrier in the selected range; and allocating at least one of the plurality of bitloading profiles to the cable modems in a manner that affects the throughput of at least one of an OFDM transmission to the cable modem and OFDMA transmission from the cable modem.
  2. 2 . The method of claim 1 where the selected range of subcarriers includes less than the number of subcarriers in the plurality of subcarriers.
  3. 3 . The method of claim 1 where the selected range of subcarriers is a single subcarrier.
  4. 4 . A method for allocating bitloading profiles to a cable modem, the method comprising: receiving error data for the cable modem spanning a plurality of subcarriers, each subcarrier having a plurality of error datum associated with it; incrementally selecting each subcarrier in the plurality of subcarriers and, for each incrementally selected subcarrier: determining a percentile value based upon an analysis of the respectively associated plurality of error datum; and using the determined percentile value to associate an aggregated error metric for the selected subcarrier; determining a plurality of bitloading profiles based on the association of the aggregated error metric for each subcarrier in the plurality of subcarriers; and allocating at least one of the plurality of bitloading profiles to the cable modems in a manner that affects the throughput of at least one of an OFDM transmission to the cable modem and OFDMA transmission from the cable modem.
  5. 5 . The method of claim 4 where the percentile value varies over the plurality of subcarriers.
  6. 6 . The method of claim 4 where lower percentile values are associated with subcarrier frequencies whose error value distributions have negative skews.
  7. 7 . The method of claim 6 including using a measurement of skew to determine the percentile value.
  8. 8 . The method of claim 4 where lower percentile values are associated with subcarriers having a higher probability of mobile interference in a subcarrier.
  9. 9 . The method of claim 8 including estimating a probability of mobile interference in a subcarrier from the error data.
  10. 10 . A CMTS having a processor configured to: receive error data for a cable modem spanning a plurality of subcarriers, each subcarrier having a plurality of error datum associated with it; incrementally select each subcarrier in the plurality of subcarriers and, for each incrementally selected subcarrier: determine a percentile value based upon an analysis of the respectively associated plurality of error datum; and use the determined percentile value to associate an aggregated error metric for the selected subcarrier; determine a plurality of bitloading profiles based on the association of the aggregated error metric for each subcarrier in the plurality of subcarriers; and allocate at least one of the plurality of bitloading profiles to the cable modems in a manner that affects the throughput of at least one of an OFDM transmission to the cable modem and OFDMA transmission from the cable modem.
  11. 11 . The CMTS of claim 10 where the percentile value varies over the plurality of subcarriers.
  12. 12 . The CMTS of claim 10 where lower percentile values are associated with subcarrier frequencies whose error value distributions have negative skews.
  13. 13 . The CMTS of claim 12 including using a measurement of skew to determine the percentile value.
  14. 14 . The CMTS of claim 10 where lower percentile values are associated with subcarriers having a higher probability of mobile interference in a subcarrier.
  15. 15 . The CMTS of claim 14 including estimating a probability of mobile interference in a subcarrier from the error data.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application Ser. No. 63/347,975 filed Jun. 1, 2022 and U.S. Provisional Patent Application Ser. No. 63/347,957 filed Jun. 1, 2022. BACKGROUND The subject matter of this application generally relates to devices, systems and methods that determine bitrate profiles in Hybrid Fiber Coax (HFC) systems. Cable Television (CATV) services have historically provided content to large groups of subscribers from a central delivery unit, called a “head end,” which distributes content to its subscribers from this central unit through a branch network comprising a multitude of intermediate nodes. Modern CATV service networks, however, not only provide media content such as television channels and music channels to a customer, but also provide a host of digital communication services such as Internet Service, Video-on-Demand, telephone service such as VoIP, and so forth. These digital communication services, in turn, require not only communication in a downstream direction from the head end, through the intermediate nodes and to a subscriber, but also require communication in an upstream direction from a subscriber, and to the content provider through the branch network. To this end, these CATV head ends include a separate Cable Modem Termination System (CMTS), used to provide high speed data services, such as video, cable Internet, Voice over Internet Protocol, etc. to cable subscribers. Typically, a CMTS will include both Ethernet interfaces (or other more traditional high-speed data interfaces) as well as RF interfaces so that traffic coming from the Internet can be routed (or bridged) through the Ethernet interface, through the CMTS, and then onto the optical RF interfaces that are connected to the cable company's hybrid fiber coax (HFC) system. Downstream traffic is delivered from the CMTS to a cable modem in a subscriber's home, while upstream traffic is delivered from a cable modem in a subscriber's home back to the CMTS. Many modern CATV systems have combined the functionality of the CMTS with the video delivery system (EdgeQAM) in a single platform called the Converged Cable Access Platform (CCAP). Still other modern CATV systems called Remote PHY (or R-PHY) relocate the physical layer (PHY) of a traditional CCAP by pushing it to the network's fiber nodes. Thus, while the core in the CCAP performs the higher layer processing, the R-PHY device in the node converts the downstream data sent by the core from digital-to-analog to be transmitted on radio frequency, and converts the upstream RF data sent by cable modems from analog-to-digital format to be transmitted optically to the core. Other modem systems push other elements and functions traditionally located in a head end into the network, such as MAC layer functionality (R-MACPHY), etc. CATV systems traditionally bifurcate available bandwidth into upstream and downstream transmissions, i.e., data is only transmitted in one direction across any part of the spectrum. For example, early iterations of the Data Over Cable Service Interface Specification (DOCSIS) specified assigned upstream transmissions to a frequency spectrum between 5 MHz and 42 MHz and assigned downstream transmissions to a frequency spectrum between 50 MHz and 750 MHz. Later iterations of the DOCSIS standard expanded the width of the spectrum reserved for each of the upstream and downstream transmission paths, but the spectrum assigned to each respective direction did not overlap. Recently, proposals have emerged by which portions of spectrum may be shared by upstream and downstream transmission, e.g., full duplex and soft duplex architectures. Orthogonal Frequency Division Multiplexing (OFDM) technology was introduced as a cable data transmission modulation technique during the creation of the CableLabs DOCSIS 3.1 specification. OFDM technology was defined for use directly in the downstream direction and was adapted for multiple access (Orthogonal Frequency Division with Multiple Access—OFDMA) for use in the upstream direction. In each direction, the relatively wide channel is subdivided into many small subcarriers. In the downstream direction, each of these subcarriers may use its own Quadrature Amplitude Modulation (QAM) level, which equates to a different bit capacity per subcarrier QAM symbol. In the upstream direction, groups of subcarriers are combined and, when time multiplexed, create the atomic unit of upstream bandwidth assignment known as a “minislot.” In the upstream direction, all subcarriers of a minislot are assigned the same QAM level and thus all subcarriers of a minislot have the same bit capacity per QAM symbol. The purpose of OFDM/OFDMA technology is to maximize the efficiency of data transmissions across a cable data network by optimizing the QAM modulation level used for each subcarrier of RF frequency bandwidth. Ideally, each cable modem would be assigned its own vector of p