OFDM Broadcast Signal Interleaving for Robust Mobile Reception
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Solution Overview
Problem
Current digital broadcast signal transmission technologies face challenges in data transmission efficiency, robustness, and network flexibility, particularly in mobile reception and indoor environments, due to the large amounts of video/audio data and additional services required for high-definition images and multi-channel audio.
Innovation Solution
The method involves encoding service data, constructing signal frames with OFDM symbols, and modulating data using an OFDM scheme to enhance transmission efficiency and robustness, while employing MIMO systems to support mobile and indoor reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If digital broadcast signals transmit large amounts of video/audio data for HD images and multi-channel audio, then service quality and content richness are improved, but data transmission efficiency and network robustness deteriorate
Solution Approach 1:
The broadcast data is segmented into multiple transport blocks, which are further divided into code blocks. Each code block is independently encoded and transmitted, allowing parallel processing and efficient utilization of available bandwidth while maintaining overall transmission efficiency despite the large total data volume.
Solution Approach 2:
The patent employs MIMO (Multiple Input Multiple Output) technology, transitioning from single-antenna transmission to multi-antenna spatial dimension. This adds a spatial dimension to data transmission, enabling simultaneous transmission of multiple data streams and significantly improving overall transmission efficiency without increasing spectral efficiency requirements.
2Adaptability or versatility
If digital broadcast signals include various additional services and data, then service functionality is improved, but transmission robustness deteriorates
Solution Approach 1:
Forward error correction codes are applied preliminarily to the data before transmission. Redundant parity bits are added in advance to enable error detection and correction at the receiver without requiring retransmission, thereby maintaining robustness even when additional services increase overall data complexity.
Solution Approach 2:
Different modulation and coding schemes are applied to different service components based on their specific requirements. Critical services receive more robust encoding with lower code rates, while less critical additional services use higher code rates, optimizing overall system robustness while supporting diverse functionality.
3Adaptability or versatility
If mobile reception equipment is used, then reception flexibility is improved, but signal reception reliability deteriorates due to signal instability
Solution Approach 1:
The system dynamically adapts transmission parameters including modulation order, code rate, and MIMO configuration based on channel conditions. Mobile receivers can maintain reliable connection by negotiating and switching between different transmission modes as signal quality changes, preserving both flexibility and reliability.
Solution Approach 2:
The system prepares multiple candidate transmission configurations in advance and selects the most appropriate one based on predicted channel conditions. For mobile reception, this includes pre-configuring fallback options that can be activated when signal quality degrades, cushioning against potential reliability issues before they occur.
4Ease of operation
If indoor reception environment is used, then reception accessibility is improved, but signal robustness deteriorates due to signal blockage and interference
Solution Approach 1:
The transmitted signal is divided into multiple frequency subcarriers and spatial streams. Indoor multipath interference and blockages affect only portions of the signal rather than the entire transmission, allowing the receiver to reconstruct the original signal from the remaining intact segments, thereby maintaining robustness while enabling indoor accessibility.
Solution Approach 2:
MIMO technology utilizes multiple spatial dimensions through multiple antennas. This spatial diversity allows the system to overcome indoor signal blockages by receiving signals through different spatial paths, maintaining robustness even when physical obstacles block direct line-of-sight paths.
Data Source
AI summary
A method is provided for transmitting broadcast signals. Service data is encoded. The encoded service data is mapped to symbols onto constellations. Data cells are frequency interleaved in a symbol among the symbols in at least one frame unit using an interleaving sequence. The interleaving sequence is generated based on a main interleaving-sequence and a symbol offset value. The interleaving sequence is generated by operating the main interleaving-sequence with the symbol offset value. The data cells are included in the symbol with a symbol index and a frame unit with a frame unit index. The frequency interleaving of the data cells operates on a frame basis. The frequency interleaving of the data cells is reset when a first frame unit is changed to a second frame unit. Data is modulated in the at least one frame unit by an Orthogonal Frequency Division Multiplexing (OFDM) scheme. The broadcast signals carrying the modulated data are transmitted.