Corrected PCR Management in CCAP Platforms
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Solution Overview
Problem
Current CCAP platforms face challenges in maintaining accurate Program Clock Reference (PCR) values due to asynchronous video transmission, leading to increased computational burden and latency, as existing methods require significant buffering and complex rate adjustments across RF interfaces.
Innovation Solution
A method for calculating a corrected PCR value using a Virtual de-jitter FIFO and phase lock loop (PLL) to determine theoretical input and output times, allowing for accurate PCR management with minimal buffering and reduced computational resources, implemented in Remote PHY and MACPHY devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional PCR management methods are used in CCAP platforms, then PCR accuracy can be maintained, but latency and computational burden increase significantly
Solution Approach 1:
The patent extracts the PCR management function from the RPD to a centralized PCR management entity (PME) located at the CCAP core. This separation allows the RPD to simply forward PCR packets without performing complex rate adjustments or buffering operations, thereby reducing latency while maintaining PCR accuracy through centralized management.
Solution Approach 2:
The patent introduces a PCR management entity (PME) as an intermediary between the encoder and the RPD. The PME receives PCR packets, performs rate adjustment calculations, and generates corrected PCR values that are then forwarded to the RPD. This intermediary handles the computational burden of PCR management, reducing the processing load and latency at the RPD while maintaining accurate PCR values.
2Measurement precision
If significant buffering is used to maintain PCR accuracy, then PCR values remain accurate, but device complexity and memory requirements increase
Solution Approach 1:
The patent removes the buffering and rate adjustment functionality from the RPD, transferring it to the centralized PME. The RPD only needs to forward PCR packets without maintaining large buffers or performing complex rate adjustments, significantly reducing device complexity and memory requirements at the RPD while the PME handles all buffering and calculation operations centrally.
Solution Approach 2:
The patent creates a universal PCR management entity (PME) that serves multiple RPDs and handles PCR management for all programs across the entire CCAP platform. This centralized multi-functional entity consolidates buffering and rate adjustment operations, reducing the need for duplicate buffering infrastructure at each RPD and lowering overall system complexity.
3Reliability
If complex rate adjustments are performed at RPD, then transmission rate synchronization is achieved, but computational load increases
Solution Approach 1:
The patent extracts the complex rate adjustment calculations from the RPD and centralizes them in the PME. The RPD only performs simple packet forwarding operations, while the PME performs all the computational-intensive rate adjustment calculations, including determining theoretical input/output times and generating corrected PCR values. This distribution significantly reduces the computational load and energy consumption at the RPD.
Solution Approach 2:
The patent introduces the PME as an intermediary that performs all rate adjustment calculations between the encoder and the RPD. The PME receives PCR packets, calculates the required rate adjustments based on encoder and transmission clock rates, generates corrected PCR values, and forwards them to the RPD. This intermediary handles all computational burden, reducing the processing load at the RPD while maintaining accurate rate synchronization.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces latency and computational load, enabling efficient PCR management with minimal buffers and easy program clock synchronization, achieving low latency comparable to IP jitter levels.
Implementation Method 1
A method for calculating a corrected PCR value using a Virtual de-jitter FIFO and phase lock loop (PLL) to determine theoretical input and output times
Data Source
AI summary
Assigning a program clock reference (PCR) value to a PCR packet. A theoretical input time and a theoretical output time is determined for a PCR packet received by a Remote PHY device (RPD) or a Remote MACPHY Device (RMD). A corrected PCR value is assigned to the PCR packet, based at least in part, on the theoretical output time and the theoretical output time. Then, the PCR packet having the corrected PCR value is transmitted to customer premises equipment (CPE) in a Converged Cable Access Platform (CCAP). Assigning a corrected PCR value to the PCR packet may be performed without learning an encoding rate associated with a program to which the PCR value is assigned.