Wireless Synchronization Using Satellite Path Variation
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Solution Overview
Problem
In wireless satellite communications using OFHMA waveforms, achieving synchronization with zero loop error and optimal convergence time is challenging due to satellite movement and carrier velocity variations, leading to increased complexity and convergence time with existing second-order servo-control solutions.
Innovation Solution
The method involves using the speed of variation of the satellite-carrier path, calculated from the derivative of the time position of the EVF service link's time beacon, to adjust the transmission time of subscriber stations, allowing for faster synchronization and zero loop error convergence, while maintaining a stability margin through a processor-based algorithm that compares loop errors with a threshold value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If second-order slaving is used to cancel loop error, then loop error approaches zero, but convergence time increases significantly
Solution Approach 1:
The subscriber station calculates the speed of variation of the satellite-carrier path in advance using the derivative of the time position of reception of the EVF service link time beacon. This preliminary calculation allows the station to anticipate and compensate for path variations, achieving zero loop error without requiring complex second-order servo control and its associated long convergence time.
2Measurement precision
If second-order servo control is implemented to maintain zero loop error, then synchronization precision improves, but system complexity increases
Solution Approach 1:
Each subscriber station independently calculates its own speed of variation of the satellite-carrier path using locally received time beacon information. This self-service approach eliminates the need for complex centralized second-order servo control systems, reducing overall system complexity while maintaining high synchronization precision.
3Loss of time
If loop gain is increased to reduce convergence time, then synchronization speed improves, but stability margin decreases
Solution Approach 1:
By pre-calculating the speed of variation of the satellite-carrier path from the time beacon, the system compensates for transit time variations before they affect synchronization. This allows the use of lower loop gain values that maintain stability margins while still achieving fast convergence, as the preliminary compensation reduces the corrective action needed during the feedback loop.
Data Source
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AI summary
The invention relates to a method and device for synchronizing a master station and one or more user stations in a wireless communication network, comprising at least one processor at each of the user stations, for calculation of the resetting of transmission time of each user, taking into account the rate of change of the satellite-user path, a processor at the master station, for measurement of the loop error and a processor for comparison of the error value to a threshold value and, when the loop error value for a user station is less than or equal to the threshold value, for giving authorisation to said user station to transmit the traffic thereof.