Timed Packet Processing for Constant Delay Gateway Networks

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Solution Overview

Problem

Conventional Edge Quadrature Amplitude Modulation (EQAM) systems experience variable transmission delays due to mismatched data processing rates, leading to buffering issues and operational disruptions in cable modems, which increase manufacturing costs and affect cable modem performance.

Innovation Solution

A Universal EQAM system that generates a strobe signal based on synchronized baseband clock manipulation, allowing for timed processing and transfer of fixed-length packets between front-end and back-end components, thereby eliminating or reducing buffering and ensuring constant data transfer delays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If large buffers are equipped in EQAM components to queue data, then data transfer capability is improved, but manufacturing cost increases and processing delays occur

Engineering Contradiction:

Improvedata transfer capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent implements periodic action by using a strobe signal to rhythmically control data transfer from the front-end to the back-end. The strobe signal is generated by multiplying the baseband clock by a custom multiplier, creating periodic transfer intervals that match the back-end processing rate. This periodic control eliminates the need for large buffers while maintaining continuous data flow, as data is transferred in controlled bursts rather than requiring simultaneous storage of large volumes.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent applies parameter changes by dynamically adjusting the strobe signal frequency through the custom multiplier. The multiplier is selected based on the ratio between the variable front-end receive data rate and the fixed back-end processing rate. By changing the strobe frequency parameter in response to varying input conditions, the system maintains optimal data transfer without requiring buffer storage capacity, thus reducing manufacturing costs while preserving productivity.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If large buffers are equipped in EQAM components to queue data, then data transfer capability is improved, but processing delays increase that disrupt cable modem operation

Engineering Contradiction:

Improvedata transfer capabilityVSAvoidprocessing delay

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The strobe signal creates periodic transfer windows that synchronize data movement with back-end processing capacity. By transferring data in regular, controlled intervals rather than continuous unregulated flow, the system maintains a steady state where data arrives at the back-end at its maximum processing rate without accumulation. This eliminates queueing delays while preserving full data transfer capability.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system implements feedback by monitoring the variable receive data rate at the front-end and adjusting the strobe signal frequency accordingly. The custom multiplier is selected based on the ratio between the current input rate and the fixed back-end processing rate. This feedback mechanism ensures that data is transferred at precisely the rate the back-end can process it, preventing both buffer overflow and processing delays that would disrupt cable modem operation.

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If variable data rates are received at the front-end, then network adaptability is improved, but synchronization with back-end processing becomes difficult

Engineering Contradiction:

Improvenetwork adaptabilityVSAvoidsynchronization reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent handles variable data rates by dynamically changing the strobe signal frequency parameter. The custom multiplier is selected based on the ratio between the variable front-end receive rate and the fixed back-end processing rate. This parameter adjustment maintains synchronization reliability across different network conditions while preserving adaptability to varying input rates.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The strobe signal acts as an intermediary between the variable-rate front-end and the fixed-rate back-end. Rather than directly connecting the two, the strobe signal mediates the data transfer by controlling when data moves from front-end to back-end. This intermediary mechanism absorbs the variability of the input rate while presenting a steady, synchronized flow to the back-end processing component.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS7720077B1Timed packet processing to regulate data transfer between components of a gateway for a constant delay network

Publication Date: 2010.05.18 CISCO TECHNOLOGY INC

AI summary

In one embodiment, a gateway for a constant delay network identifies a baseband clock that is synchronized by exchanging synchronization messages over a packet switched network. The gateway then generates a strobe by manipulating the identified baseband clock using a custom multiplier that is selected according to transmission variables. The gateway then signals a front end component to process fixed length packets for transfer to a back end component according to the generated strobe, which can reduce or eliminate buffering by the back end component and can improve cable modem operation.