Sampling Frequency Generation Stabilization for Mobile Terminals
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In mobile communication systems, generating a stable sampling frequency that remains constant despite terminal velocity is challenging due to Doppler effects and the need for precise clock synchronization between base stations and terminals, leading to potential aliasing issues.
Innovation Solution
A method and apparatus that extract frequency offsets from channel signals, calculate shifts, and adjust sampling frequencies to maintain a constant frequency, using a negative feedback loop and multiple links to compensate for Doppler-induced frequency changes, ensuring stable sampling frequencies across varying velocities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sampling frequency is generated using the terminal's reference clock and RF center frequency compensation, then the system is simple to implement, but the sampling frequency changes with terminal velocity causing aliasing
Solution Approach 1:
The patent introduces a feedback mechanism where the base station measures the actual sampling frequency of received signals and feeds back frequency offset information to the terminal. The terminal then adjusts its sampling frequency based on this feedback, forming a closed-loop control system that maintains sampling frequency stability despite terminal mobility.
Solution Approach 2:
The patent changes the sampling frequency parameter dynamically based on feedback from the base station. Instead of using a fixed reference clock frequency, the terminal adjusts its sampling frequency to compensate for Doppler effects and maintain synchronization with the base station's expected sampling rate.
2Productivity
If guard band is reduced to increase data throughput, then communication efficiency improves, but aliasing occurs when sampling frequency errors are large
Solution Approach 1:
The feedback mechanism enables precise sampling frequency control, reducing sampling frequency errors to a level where smaller guard bands can be used without causing aliasing. This allows the system to maintain high data throughput while preventing aliasing through active frequency compensation rather than conservative guard band design.
3Productivity
If sampling frequency is increased to support higher bandwidth and mobility, then communication throughput improves, but sampling frequency errors become more significant
Solution Approach 1:
The feedback mechanism becomes increasingly important at higher sampling frequencies and mobilities. By continuously measuring and compensating for frequency offsets, the system maintains accurate sampling despite the larger absolute frequency changes that occur at higher velocities and bandwidths, enabling high throughput communication in mobile environments.
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 stabilizes sampling frequencies regardless of terminal velocity, reducing aliasing and allowing for higher data throughput by eliminating the need for large guard bands, thus enhancing communication efficiency in high-mobility environments.
Implementation Method 1
sampling frequency changes in proportion to frequency error occur in a channel, caused by the Doppler effect
Data Source
AI summary
A method and apparatus for generating a sampling frequency are provided. A signal is generated, of which frequency is a predetermined multiple of a reference clock, and a frequency offset in a channel is extracted from the entire frequency offset. The amount of shift is calculated by dividing the extracted frequency offset by a predetermined value, and a final sampling frequency is obtained by shifting the frequency of the generated signal by the amount of shift.