Broadcast Receiver Nulling and Cyclic Addition for Inter-Frame Interference
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Solution Overview
Problem
Digital terrestrial broadcast systems, such as DTMB, face inter-frame interference due to multi-path channels, which conventional methods struggle to fully mitigate, especially when delay waves exceed the frame header length, leading to significant interference even with small delay wave powers.
Innovation Solution
A receiving apparatus that estimates multi-path channels, generates and removes replicas of the frame header, forcefully nulls inter-frame interference, and performs cyclic addition between frame portions to maintain signal periodicity, effectively reducing interference by comparing and addressing both front and rear interference components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the frame header portion is removed based on channel estimate and cyclic addition is performed to eliminate inter-frame interference, then inter-frame interference within the frame is eliminated, but inter-frame interference from adjacent frames occurs when the maximum delay time exceeds the frame header length
Solution Approach 1:
The patent performs preliminary nulling of the frame header portion before cyclic addition. By proactively removing the frame header based on channel estimates prior to the cyclic addition operation, the patent prevents the generation of inter-frame interference from adjacent frames while maintaining the ability to eliminate intra-frame interference through subsequent processing steps
Solution Approach 2:
The patent extracts and removes the frame header portion from the received signal based on channel estimates. This extraction separates the known frame header from the data portion, allowing independent processing that eliminates interference while preserving the cyclic structure needed for demodulation
2Stability of the object's composition
If the frame header is removed and cyclic addition is performed, then signal periodicity is restored for demodulation, but interference components remain when delay time is large
Solution Approach 1:
The patent performs preliminary nulling of the frame header portion before cyclic addition. By proactively removing the frame header based on channel estimates prior to the cyclic addition operation, the patent prevents the generation of inter-frame interference from adjacent frames while maintaining the ability to eliminate intra-frame interference through subsequent processing steps
Solution Approach 2:
The patent uses channel estimates obtained from the known frame header to identify and null interference components. The very knowledge gained from the frame header (which would normally cause interference) is converted into a beneficial tool for detecting and removing interference through channel estimation and replica generation
Data Source
AI summary
A receiving apparatus receives a digital modulation signal. The receiving apparatus has a receiving part for down-converting the digital modulation signal to a baseband signal and to obtain channel estimates, a channel estimation part for estimating a multi-path channel, a first replica generation part for generating a first replica, based on the channel estimates obtained by the channel estimation part, a first replica removal part for removing the first replica from a target frame in the baseband signal, a nulling part for forcefully nulling he baseband signal for at least a portion of the time period where an inter-frame interference occurs due to a delay wave having a delay time longer than the known signal, and a cyclic-addition part for performing cyclic-addition between a front side portion and a rear side portion in the target frame, including the portion nulled by the nulling part.