RPD Phase Correction via Periodic Holdover Modes

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Solution Overview

Problem

In R-PHY network architectures, synchronizing Remote PHY Devices (RPDs) with both the R-PHY core and cellular networks is challenging, especially when connection to the timing grandmaster is lost, leading to phase and frequency drifts that require correction without interrupting service.

Innovation Solution

Implementing an alternating cycle of short time increments where the EnB is either locked to the RPD's frequency or in holdover, allowing the RPD to make large frequency changes during holdover intervals and smaller adjustments when locked, thereby reducing the time needed to correct phase errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If the RPD makes large frequency changes to correct phase errors quickly, then the synchronization time is reduced, but the LTE mobile system performance deteriorates due to excessive frequency adjustments

Engineering Contradiction:

Improvesynchronization correction timeVSAvoidLTE mobile system performance

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The patent implements periodic action by alternating between two operational modes: holdover mode where large frequency changes are permitted for rapid phase correction, and locked mode where frequency changes are restricted to maintain LTE performance. This periodic switching enables the system to achieve fast synchronization while periodically ensuring service quality, reducing correction time from 34 hours to 3-8 hours without permanent degradation of LTE performance

Inventive Principle:

Principle #19Periodic action

2Reliability

If the RPD remains locked to the master clock continuously, then LTE mobile system performance is maintained, but the phase error correction time increases significantly

Engineering Contradiction:

ImproveLTE mobile system performanceVSAvoidphase error correction time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies dynamics by making the operational mode flexible and adaptive rather than static. The system dynamically switches between holdover mode (permitting large frequency changes for fast correction) and locked mode (maintaining LTE performance) based on service availability and correction needs. This dynamic approach allows the RPD to optimize between correction speed and performance maintenance at different times

Inventive Principle:

Principle #15Dynamics

3Loss of time

If the RPD enters holdover mode continuously, then phase error correction is accelerated, but service interruption occurs

Engineering Contradiction:

Improvephase error correction timeVSAvoidservice continuity

Core Design Contradiction:

Loss of timeVSEase of operation

Solution Approach 1:

The patent resolves this contradiction through periodic action by alternating between holdover mode (fast correction but potential service interruption) and locked mode (service continuity but slower correction). The system strategically schedules holdover periods when service interruption is acceptable, achieving rapid phase correction from 34 hours to 3-8 hours while maintaining service during locked periods

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS12335030B2Systems and methods for large phase correction in R-PHY network architectures

Publication Date: 2025.06.17 ARRIS ENTERPRISES LLC

AI summary

Systems and methods for regaining phase synchronization between a CMTS core and an RPD, where the phase synchronization is regained over repeated temporal periods preferably divided between a first interval having a frequency adjustment of a first magnitude and a second interval having a frequency adjustment of a second magnitude.