Ranging-Based Clock Synchronization for Home Cable Networks
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Solution Overview
Problem
Existing home networking technologies, such as MoCA 1.x, face challenges in accurately synchronizing local clock times across nodes due to propagation delays and clock drifts, leading to unpredictable packet arrival times and increased inter-frame gaps, which affect network efficiency and performance.
Innovation Solution
Implementing ranging methods to measure and adjust propagation delays between nodes, allowing for more precise synchronization of local clock times and reducing inter-frame gaps, thereby improving packet arrival predictability and reducing the cyclic prefix length needed for OFDMA schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional clock synchronization methods are used in MoCA networks, then network devices can communicate, but packet arrival times become unpredictable and inter-frame gaps increase
Solution Approach 1:
The patent applies preliminary action by performing ranging measurements before actual data transmission to pre-calculate propagation delays. Nodes exchange ranging requests and responses to measure the time of flight, then use these pre-measured values to adjust clock synchronization and predict packet arrival times accurately, eliminating the need for reactive adjustments during transmission.
Solution Approach 2:
The patent implements feedback through the ranging protocol where nodes continuously measure propagation delays and use this information to adjust their clock synchronization. The estimated propagation delay values are fed back to nodes to modify their timing predictions, creating a closed-loop system that improves packet arrival predictability over time.
2Measurement precision
If ranging measurements are implemented to synchronize clock times, then packet arrival predictability improves, but network complexity increases
Solution Approach 1:
The patent applies universality by designing the ranging protocol to serve multiple functions: clock synchronization, propagation delay measurement, and packet arrival time prediction. The same ranging exchange mechanism used to measure time of flight also provides the data needed for precise synchronization and predictive buffering, eliminating the need for separate complex synchronization systems.
Solution Approach 2:
The patent implements self-service by having nodes automatically perform ranging measurements and adjust their own clock synchronization based on measured propagation delays. The system self-calibrates without requiring external intervention or complex manual configuration, with nodes autonomously exchanging ranging requests and responses to determine their timing relationships.
3Reliability
If larger inter-frame gaps are used to account for clock synchronization uncertainties, then packet collisions are avoided, but network throughput decreases
Solution Approach 1:
The patent replaces the mechanical approach of using large fixed inter-frame gaps to prevent collisions with a more precise electronic timing system based on ranging measurements. Instead of relying on conservative time margins, the system uses measured propagation delays to calculate exact packet arrival times, enabling precise scheduling that eliminates collisions without requiring excessive inter-frame gaps.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting timing parameters based on measured propagation delays. Rather than using fixed conservative inter-frame gaps, the system changes the timing parameters (expected packet arrival times, inter-frame gap durations) based on the actual measured characteristics of each network segment, optimizing throughput for each specific environment.
Data Source
AI summary
According to various embodiments of the disclosure, systems, methods and apparatuses are provided for using ranging to improve network efficiency. In particular, various embodiments of the disclosure provide ranging to improve local clock time synchronization. According to one embodiment, a method for synchronizing a plurality of nodes on a communication network is provided, comprising: exchanging local clock times between a first node and a second node over the communication network; performing a ranging method between the first and second nodes based on the local clock times exchanged between the first and second nodes, wherein the ranging method results in an estimated propagation delay between the first and second nodes; and adjusting the local clock times of the first and second nodes based on the estimated propagation delay, thereby resulting in a synchronized local clock time at the first and second nodes.