Frame Synchronization Using Continual Pilot Correlation
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Solution Overview
Problem
Current frame synchronization methods in DVB-H systems are complex and time-consuming, requiring extensive calculations and long periods to achieve synchronization, especially due to the non-uniform distribution of pilot carriers and limited power gain of pilot constellations, which complicates frequency offset estimation.
Innovation Solution
The method involves calculating correlation values between consecutive continual pilot symbols to determine the first symbol of the frame using a pre-established relationship between sequence signs, and optimizing pilot distribution with synchronous and scattered pilots to reduce synchronization time and improve power gain, allowing for faster and more accurate frame synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frame synchronization is performed using TPS and scattered pilots with non-uniform pilot distribution, then channel estimation can be achieved, but the synchronization time becomes excessively long (exceeding frame duration) and calculation complexity increases
Solution Approach 1:
The patent divides the frame synchronization process into two independent stages: first achieving frame synchronization using only continual pilots (which are uniformly distributed and abundant), then performing channel estimation using scattered pilots. This segmentation allows the synchronization stage to complete quickly without waiting for scattered pilots, reducing synchronization time below frame duration while maintaining accuracy through the two-stage approach.
Solution Approach 2:
The patent performs frame synchronization as a preliminary action before channel estimation. By using continual pilots to establish frame boundaries and synchronization first, the system creates a foundation that enables subsequent scattered pilot processing to occur at the correct timing, thereby reducing overall synchronization time while preserving measurement precision.
2Measurement precision
If TPS-based frame synchronization is implemented, then frame boundaries can be identified, but the calculation complexity and implementation complexity increase significantly
Solution Approach 1:
The patent extracts the frame synchronization function from the channel estimation process. By using only continual pilots for synchronization (separating this function from scattered pilots used for channel estimation), the system simplifies the synchronization algorithm to a straightforward correlation-based approach, reducing calculation and implementation complexity while maintaining frame boundary detection accuracy.
Solution Approach 2:
Instead of using scattered pilots (which are sparse and require complex processing) for frame synchronization as in conventional methods, the patent inverts the approach by using continual pilots (which are abundant and uniformly distributed) for synchronization. This inversion simplifies the mathematical operations required and reduces implementation complexity while preserving synchronization accuracy.
3Power
If pilot constellation power is normalized to 16/9, then power gain over data constellations is achieved, but the gain is only about 2.5 dB which is insufficient for effective synchronization and channel estimation
Solution Approach 1:
The patent changes the parameter of pilot constellation power normalization from the conventional 16/9 ratio to a higher value that provides at least 3 dB power gain over data constellations. This parameter change increases the signal-to-noise ratio for pilot symbols, thereby improving the precision of both synchronization and channel estimation operations while maintaining the necessary power relationship between pilots and data.
4Productivity
If continual pilots are spaced with minimum distance of 3 sub-carriers in 4K mode, then bandwidth utilization is improved, but frequency offset estimation becomes unreliable when offset is -20 ppm to 20 ppm
Solution Approach 1:
The patent segments the frequency offset estimation process into two independent stages: first estimating integral frequency offset using the uniformly distributed continual pilots (which provide reliable coarse estimation even with 3-subcarrier spacing), then estimating fractional frequency offset using scattered pilots after frame synchronization is achieved. This segmentation allows bandwidth-efficient pilot spacing while maintaining estimation precision through the two-stage approach.
Solution Approach 2:
The patent performs integral frequency offset estimation as a preliminary action using continual pilots before proceeding to fractional offset estimation. This preliminary estimation removes the large integer component of frequency offset, allowing subsequent fine estimation to converge more reliably. This approach maintains estimation precision despite the reduced pilot spacing that improves bandwidth utilization.
Data Source
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AI summary
A method of frame synchronization includes: inserting synchronous pilots including odd synchronous pilots and even synchronous pilots in a frame; transmitting first signals on the odd synchronous pilots, and transmitting second signals of inverse values of the first signals transmitted on the odd synchronous pilots on the even synchronous pilots; synchronizing the frame according to the odd synchronous pilots and the even synchronous pilots. With the method, system and apparatus provided by embodiments of the present invention, complexity of the frame synchronization may be decreased and delay of the frame synchronization may be reduced.