OFDM Broadcast Signal Framing With NU-QAM Noise Robustness
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Solution Overview
Problem
Current digital broadcasting technologies, such as DVB-C2 and DVB-T2, face challenges in efficiently transmitting and receiving signals with increased data sizes and channel numbers, requiring improved methods for error correction and noise robustness.
Innovation Solution
The method involves using Orthogonal Frequency Division Multiplexing (OFDM) for signal modulation and demodulation, along with a shortened and punctured Low Density Parity Check (LDPC) decoding scheme, and modifying Quadrature Amplitude Modulation (QAM) using Binary Reflected Gray Code (BRGC) to create Non-uniform QAM (NU-QAM) constellations, which enhance noise robustness and reduce energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional QAM modulation is used, then the system is simple to implement, but noise robustness is insufficient
Solution Approach 1:
The patent applies asymmetry by introducing a virtual carrier in the frequency domain that is asymmetrically positioned relative to the data carriers. This virtual carrier, which carries no data, is used to generate a pilot signal that improves noise robustness. The asymmetric arrangement of the virtual carrier allows for better noise cancellation while maintaining system simplicity
Solution Approach 2:
The patent introduces a virtual carrier as an intermediary element between the data carriers and the noise environment. This virtual carrier serves as a mediator that generates a pilot signal, which in turn helps cancel noise affecting the data carriers. The virtual carrier acts as an intermediate component that improves overall system reliability without requiring complex modulation schemes
2Productivity
If more data carriers are added to increase data transmission capacity, then data transmission efficiency improves, but susceptibility to burst errors and frequency selective interference increases
Solution Approach 1:
The virtual carrier serves as an intermediary that generates a pilot signal used to cancel frequency selective interference and burst errors. By introducing this intermediate element, the system can handle larger numbers of data carriers while protecting against the increased susceptibility to interference that comes with higher data transmission capacity
Solution Approach 2:
The patent segments the frequency spectrum by introducing a virtual carrier that is separated from the data carriers. This segmentation allows the virtual carrier to independently generate a pilot signal that can be used to cancel interference affecting the data carriers, thereby protecting the overall system while maintaining high data transmission efficiency
3Reliability
If pilot signals are transmitted to improve noise cancellation, then noise robustness improves, but transmission bandwidth is consumed
Solution Approach 1:
The virtual carrier serves multiple functions: it acts as both a data-carrying element (when configured as a data carrier) and as a pilot signal generator (when configured as a virtual carrier). This multi-functionality allows the system to improve noise robustness without consuming additional bandwidth, as the same frequency resource can serve dual purposes depending on the system configuration
Solution Approach 2:
The patent changes the parameter of carrier utilization by introducing the concept of a virtual carrier that can be dynamically configured. By changing the state of a carrier from data-carrying to pilot-generating, the system can improve noise robustness without adding new frequency resources. The parameter change allows the same bandwidth to be used more efficiently for both data transmission and noise cancellation
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 improves data transmission efficiency, reduces noise susceptibility, and allows for more robust signal processing with reduced energy usage, enabling better support for high-definition video and audio services.
Implementation Method 1
modulating the signal frame by an Orthogonal Frequency Division Multiplexing (OFDM) method
Implementation Method 2
demodulating received signals by use of an Orthogonal Frequency Division Multiplexing(OFDM) method
Data Source
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Figure 5
AI summary
A method of transmitting broadcasting a signal, modulating the signal frame by an Orthogonal Frequency Division Multiplexing (OFDM) method wherein the preamble symbols are divided in frequency direction into at least one Layer 1 (L1) block of same bandwidth, and the data slices have an arbitrary bandwidth not to exceed the L1 block bandwidth.