Variable-Length Modulation for IoT Downlink Rate and Coverage
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Solution Overview
Problem
Existing IoT devices face challenges in achieving efficient downlink transmission due to limited power consumption and the inability to generate local high-frequency oscillations, leading to low transmission efficiency and inflexible resource allocation.
Innovation Solution
A communication method that dynamically adjusts the length of modulation symbols based on coverage levels, using amplitude or frequency shift keying modulation, to optimize transmission rate and coverage by indicating symbol lengths through preambles or control information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If envelope detection method is used for downlink transmission, then terminal device power consumption is reduced, but downlink transmission efficiency deteriorates
Solution Approach 1:
The patent changes the modulation parameter by introducing variable-length modulation symbols with different lengths (first length and second length) to convey different amounts of information. This allows the system to adapt the information capacity to the available power consumption budget, resolving the contradiction between low power consumption and high transmission efficiency.
Solution Approach 2:
The patent makes the modulation symbol length dynamic by allowing the network device to select between different lengths based on coverage levels and transmission requirements. This dynamic adaptation enables the system to optimize the balance between power consumption and transmission efficiency in different operational scenarios.
2Device complexity
If fixed modulation symbol length is used, then device complexity is reduced, but transmission rate adaptability deteriorates
Solution Approach 1:
The patent introduces variable-length modulation symbols as a parameter change that enables different transmission rates. By defining multiple discrete length options (first length for higher rate, second length for lower rate), the system achieves adaptability without requiring continuous or complex parameter adjustment mechanisms.
Solution Approach 2:
The patent segments the modulation symbol into different length categories (first length and second length) corresponding to different coverage levels and transmission requirements. This segmentation allows the system to select appropriate symbol lengths for different scenarios, achieving adaptability while maintaining relatively simple device architecture.
3Reliability
If longer modulation symbol length is used, then coverage performance is improved, but transmission rate deteriorates
Solution Approach 1:
The patent uses parameter changes by establishing a direct relationship between modulation symbol length and transmission characteristics: longer symbols (second length) provide better coverage performance for distant terminals, while shorter symbols (first length) enable higher transmission rates for nearby terminals with better signal conditions.
Solution Approach 2:
The patent implements dynamic adaptation by allowing the network device to select the appropriate modulation symbol length based on the terminal's coverage level and transmission requirements. This dynamic selection optimizes the balance between coverage performance and transmission rate for each specific communication scenario.
Data Source
AI summary
Example communication methods and apparatuses are described. In one example method, a network device determines a first signal, determines a length of a modulation symbol of a second signal based on the first signal, and sends the first signal and the second signal to a terminal device. The terminal device determines the length of the modulation symbol of the second signal based on the first signal, and demodulates the second signal based on the length of the modulation symbol of the second signal. A length of a modulation symbol of the first signal is one of a plurality of lengths of modulation symbols. The first signal is a preamble signal or a signal used by the terminal device for synchronization. The second signal is a data signal after the first signal.