Full Duplex Cable Modem Scheduling via Interference Grouping

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Solution Overview

Problem

Cable network architectures face bandwidth limitations due to the Shannon channel capacity limit, with conventional upgrades being costly and limited by capital expenditure budgets, making it challenging to extend frequency spectrum beyond 1.2 GHz and achieve full downstream/upstream throughput matching standards like GPON without extensive network upgrades.

Innovation Solution

Implementing a method to categorize cable modems into interference groups and use intelligent media access control scheduling to coordinate upstream and downstream transmissions, enabling full duplex communication by suppressing self-interference and inter-cable modem interference through adaptive interference cancellation and advanced MAC scheduling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional cable network architectures are used, then the network can operate with existing infrastructure, but the bandwidth is limited by the Shannon channel capacity limit and cannot be extended beyond 1.2 GHz

Engineering Contradiction:

ImprovebandwidthVSAvoidfrequency spectrum extension

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent segments cable modems into different interference groups based on their physical location and interference characteristics. By dividing the network into segments that can be independently scheduled, the system can manage interference more effectively and extend the usable frequency spectrum beyond traditional limits, thereby increasing bandwidth without requiring complete network replacement.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic scheduling that adapts to changing network conditions by adjusting which cable modems transmit and receive at different time slots. This dynamic approach allows the network to flexibly utilize available spectrum resources and extend operational frequency ranges while managing interference, thus improving bandwidth without static infrastructure changes.

Inventive Principle:

Principle #15Dynamics

2Productivity

If frequency spectrum is extended beyond 1.2 GHz, then bandwidth can be increased, but extensive network upgrades are required which exceed capital expenditure budgets

Engineering Contradiction:

ImprovebandwidthVSAvoidnetwork upgrade cost

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent uses digital signal processing techniques that create virtual copies of signal processing functions through software and algorithms rather than requiring physical hardware changes throughout the network. By implementing interference cancellation and scheduling through digital processing, the system can extend frequency spectrum usage without the costly physical upgrades that would otherwise be necessary.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent changes operational parameters of existing network components, specifically adjusting frequency allocation and scheduling parameters to enable full-duplex operation. By modifying how existing infrastructure operates rather than replacing it, the system can extend bandwidth into higher frequency ranges without incurring the capital expenditure required for physical network upgrades.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If full duplex communication is implemented, then near-symmetric downstream and upstream throughput can be achieved, but self-interference and inter-cable modem interference must be suppressed

Engineering Contradiction:

Improvethroughput symmetryVSAvoidself-interference

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful self-interference signal into a useful reference signal for interference cancellation. By using the transmitted signal itself as a reference to subtract from the received signal, the system can eliminate self-interference and enable full-duplex operation with near-symmetric throughput. This transforms the harmful interference into a beneficial tool for achieving the desired communication performance.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces digital signal processing algorithms as intermediaries between the transmitted and received signals. These algorithms act as mediators that separate and cancel interference components while preserving useful signal components, enabling full-duplex communication by managing both self-interference and inter-cable modem interference without preventing the underlying physical phenomenon.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10033542B2Scheduling mechanisms in full duplex cable network environments

Publication Date: 2018.07.24 CISCO TECHNOLOGY INC

AI summary

An example method for scheduling in full duplex cable network environments is provided and includes categorizing a plurality of cable modems in a cable network into interference groups, scheduling upstream transmissions and downstream receptions for cable modems in each interference group, such that no cable modem of any one interference group transmits upstream in a frequency range simultaneously as another cable modem in the same interference group receives downstream in the frequency range, generating scheduling information of the scheduling, and transmitting the scheduling information to the cable modems.