OFDM Digital Radio Coding for Long-Range Low-Power Links
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current digital radio systems, such as Wi-SUN, face limitations in data rate and range when communicating over long distances with restricted power levels, like 1 Watt, which is insufficient for connections between distant locations like cities, requiring severe data rate reduction.
Innovation Solution
The implementation of advanced error coding and modulation techniques, including Bose-Chaudhuri-Hocquenghem (BCH) and low-density parity-check (LDPC) coding for payload data, combined with convolutional coding for configuration headers, and the use of frequency diversity to enhance signal robustness and range without increasing power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If advanced error coding (BCH-LDPC) and frequency diversity are used for payload data, then coding efficiency and data rate improve, but implementation complexity increases
Solution Approach 1:
The patent segments the data into two distinct types: configuration headers and payload data. Configuration headers use traditional convolutional coding for backward compatibility, while payload data employs advanced BCH-LDPC coding for higher efficiency. This segmentation allows the system to adopt complex coding where it benefits most without unnecessarily complicating the entire system.
Solution Approach 2:
Different coding schemes are applied to different parts of the data stream based on their specific requirements. The configuration header portion uses simpler convolutional coding suitable for its structure and requirements, while the payload portion utilizes the more powerful BCH-LDPC coding. This local optimization of coding quality matches the technical capabilities to the specific needs of each data type.
2Reliability
If frequency diversity is applied to enhance signal robustness, then communication reliability improves, but signal processing complexity increases
Solution Approach 1:
The patent combines frequency diversity techniques with the BCH-LDPC coding scheme for payload data. By merging these two approaches, the system achieves enhanced signal robustness through frequency diversity while the coding provides additional error protection. This combination allows the system to tolerate channel variations and interference more effectively than either technique alone.
3Use of energy by moving object
If power output is limited to 1 Watt, then energy consumption remains controlled, but communication range is severely limited
Solution Approach 1:
The patent changes the coding parameters from traditional convolutional coding to advanced BCH-LDPC coding with optimized code rates and iteration counts. This parameter change significantly improves the coding gain, allowing the system to achieve better error correction performance at the same transmit power level, thereby extending the effective communication range without increasing power consumption.
Solution Approach 2:
The patent creates multiple copies of data through frequency diversity, where the same information is transmitted across multiple frequency subcarriers. This copying approach ensures that even if some frequency paths experience fading or interference, the receiver can reconstruct the original data from the remaining copies, effectively extending reliable communication range without additional power.
4Productivity
If different forward error encoding methods are used for headers and payload, then coding efficiency improves, but system complexity increases
Solution Approach 1:
The patent segments the data into two distinct types: configuration headers and payload data. Configuration headers use traditional convolutional coding for backward compatibility, while payload data employs advanced BCH-LDPC coding for higher efficiency. This segmentation allows the system to adopt complex coding where it benefits most without unnecessarily complicating the entire system.
Solution Approach 2:
The system dynamically selects different coding schemes based on the data type being transmitted. The dual-coding architecture allows flexible adaptation: convolutional coding for configuration information and BCH-LDPC for payload data. This dynamic approach optimizes coding efficiency for each data type while maintaining overall system manageability through clear separation of coding paths.
Data Source
AI summary
A digital radio OFDM modulator and demodulator provide an efficient mode and a backwards-compatible mode to work with IEEE 802.15.4g or a similar standard. In backwards-compatible mode, they use a single method for error encoding physical header and payload transmit data, and a single method for detecting and correcting errors in physical header and payload receive data. In efficient mode, they use two different methods. The payload is BCH-LDPC encoded. They may also use mapping constellations that are not available in IEEE 802.15.4g, including 64-QAM, 256-QAM, and APSK. To ensure that physical header data can be received more robustly than payload data, they use frequency diversity of the physical header data, and selection maximal ratio combining (SMRC) in the demodulator to reduce the bit error rate (BER) at a low cost.