Timing Server Gradual Clock Adjustment for DOCSIS Re-synchronization
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Solution Overview
Problem
In DOCSIS communication systems, timing clients may drift when disconnected from the timing server, leading to temporary loss of communication with customer premise equipment if sudden timing correction values are applied upon reconnection, causing upstream transmission collisions and service interruptions.
Innovation Solution
The system employs a timing server to determine propagation delays and generate timing correction values, allowing timing clients to gradually adjust their internal clocks to synchronize with the server's master clock, minimizing disruptions by comparing absolute differences with configurable threshold values and updating local time stamps accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If timing clients apply timing correction values immediately upon reconnection to the timing server, then timing synchronization is restored quickly, but upstream transmission collisions occur and communication is temporarily lost
Solution Approach 1:
The patent applies preliminary action by having the timing client gradually adjust its local clock in incremental steps before fully applying the timing correction value. This gradual adjustment process prevents sudden timing shifts that would cause upstream transmission collisions, while still achieving complete resynchronization with the timing server.
Solution Approach 2:
The patent implements dynamics by making the timing adjustment process adaptive and gradual rather than static and immediate. The timing client dynamically adjusts its local clock in multiple incremental steps, allowing the system to adapt to the drift that occurred during disconnection while avoiding the harmful effects of sudden correction.
2Duration of action of stationary object
If timing clients use internal clocks during disconnection from the timing server, then communication continuity is maintained, but timing drift occurs over time
Solution Approach 1:
The patent applies self-service by enabling the timing client to autonomously maintain communication using its internal clock during disconnection from the timing server. The client independently manages timing without external reference, ensuring communication continuity while accepting the natural drift that occurs.
Solution Approach 2:
The patent implements feedback by having the timing client compare its drifted local clock with the timing server's master clock upon reconnection. This feedback mechanism allows the client to determine the extent of drift and calculate the appropriate correction values needed to resynchronize with the server.
3Reliability
If the timing server determines propagation delays and generates timing correction values, then timing synchronization is achieved, but service disruptions occur during re-synchronization
Solution Approach 1:
The patent applies preliminary action by having the timing server determine propagation delays and generate timing correction values in advance, before the client fully re-synchronizes. This allows the correction process to be initiated proactively, reducing the duration of service disruptions during re-synchronization.
Solution Approach 2:
The patent implements partial action by having the timing client apply timing correction values in incremental steps rather than all at once. This partial application approach maintains service continuity while still achieving complete resynchronization, thereby minimizing service disruption duration.
Data Source
AI summary
Systems and methods of this disclosure can operate to re-synchronize timing between communication devices and can include a timing server. The timing server can provide timing messages containing timing correction values to communication devices that can synchronize the communication devices. If communication devices fail to receive timing messages, the communication devices may continue to provide communication services using their internal clocks that can drift over time. When timing messages are restored, the timing correction values can be significant enough to result in the loss of communications if immediately applied by communication devices. By gradually applying timing corrections over a period of time approaching the received timing correction value, communication devices can achieve re-synchronization while avoiding and/or minimizing the loss of communications.