OFDM Pilot Symbols for Fast Channel Synchronization
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Solution Overview
Problem
Conventional digital video broadcast service discovery in wireless communications systems, such as DVB-H, is inefficient due to reliance on trial-and-error methods for channel synchronization, requiring extensive time and bandwidth, especially when detecting non-DVB-H services, which hampers user experience and system efficiency.
Innovation Solution
Introduction of specific pilot symbols with known characteristics that remain consistent across different digital video broadcast operation modes, allowing for faster channel search and service discovery by decoding these symbols without trial-and-error methods, thereby identifying digital video broadcast signals efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If trial-and-error methods are used for channel synchronization in conventional digital video broadcast systems, then channel search can be performed, but the time required for service discovery increases significantly
Solution Approach 1:
The patent introduces preliminary synchronization symbols with known characteristics before the actual data transmission. These symbols are designed to be easily distinguishable and allow the receiver to perform synchronization and frequency offset estimation in advance, eliminating the need for time-consuming trial-and-error methods during service discovery.
Solution Approach 2:
The patent uses pilot symbols as intermediary elements that carry known information patterns. These pilot symbols act as mediators between the transmitter and receiver, enabling the receiver to detect frequency offsets and synchronize timing without having to systematically test multiple hypotheses, thus dramatically reducing service discovery time.
2Quantity of substance
If PSI or SI signaling is used for service discovery, then channel information can be obtained, but the bandwidth consumption increases and system efficiency decreases
Solution Approach 1:
The patent extracts the essential synchronization information into dedicated pilot symbols that are transmitted alongside the data. By separating the synchronization function from the data transmission, the system avoids the need for repeated PSI/SI signaling tables, thereby reducing bandwidth consumption while maintaining synchronization accuracy.
Solution Approach 2:
The pilot symbols serve multiple functions simultaneously: they provide frequency offset estimation, enable timing synchronization, and facilitate service discovery. This multi-functionality eliminates the need for separate signaling mechanisms, reducing overall bandwidth requirements and improving system efficiency.
3Ease of operation
If conventional synchronization methods are used, then channel search can be performed, but the user experience deteriorates due to slow service discovery
Solution Approach 1:
The patent employs distinct known patterns or signatures in the pilot symbols that create easily distinguishable correlation peaks. By designing the pilot symbols with unique temporal or spectral characteristics, the receiver can rapidly identify and lock onto the correct channel without confusion, significantly improving user experience through faster service discovery.
Data Source
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AI summary
Embodiments are directed to first and second OFDM pilot symbols. The first and second pilot symbols have first and second sets, respectively, of allowed, forbidden, and active carrier frequencies. The second sets of carrier frequencies are formed by frequency shifting the respective first sets by a predetermined frequency. A receiving method is directed to frequency translating part of a first received pilot symbol by one carrier interval in a first direction, frequency translating part of a second received pilot symbol by one carrier interval in a second direction that is opposite from the first direction, and forming a correlation by multiplying the frequency translated parts of the first and second pilot symbols by complex conjugates of parts of the pilot symbols upon which frequency translation has not been performed, and summing the multiplication results.