Hybrid Modulation for Mobile Optical Wireless Capacity
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Solution Overview
Problem
Conventional adaptive modulation techniques for mobile optical wireless communication systems face challenges in maintaining optimal spectral efficiency and transmission capacity due to discrete modulation format correspondence with transmission distance and high processing complexity, leading to reduced uplink efficiency and unreliable transmission performance.
Innovation Solution
A capacity optimization method that acquires position and orientation information of a receiver, calculates electrical SNR, and adjusts modulation formats to achieve a hybrid BER within a preset threshold, maximizing transmission capacity by alternately transmitting symbols in different modulation formats based on terminal movement states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional adaptive modulation technique is used with single modulation format, then transmission quality can be ensured at long distances, but spectral efficiency cannot be optimized when terminal is between transmission distance thresholds of two modulation formats
Solution Approach 1:
The patent combines multiple modulation formats (first modulation format and second modulation format) into a hybrid modulation scheme. The transmit end alternately transmits symbols using both modulation formats within the same data frame, allowing the system to achieve both reliable transmission quality and optimized spectral efficiency by dynamically adjusting the proportion of each format based on channel conditions.
Solution Approach 2:
The patent implements dynamic hybrid modulation where the transmit end adaptively adjusts the proportion of symbols using first modulation format versus second modulation format based on real-time channel state information. This dynamic adjustment allows the system to transition smoothly between different transmission quality requirements and spectral efficiency goals, rather than being constrained to fixed discrete modulation format selections.
2Productivity
If multi-carrier OFDM technology is used to improve spectral efficiency, then spectral efficiency is enhanced, but feedback overhead increases and processing complexity rises
Solution Approach 1:
The patent extracts and eliminates the need for complete channel state information feedback by using a simplified feedback mechanism. Instead of requiring full channel state information for each subcarrier as in OFDM, the system uses a reduced feedback approach that only requires minimal channel quality indicators, significantly reducing feedback overhead and processing complexity while maintaining spectral efficiency improvements.
Solution Approach 2:
The patent employs a simplified, lightweight feedback mechanism that uses minimal uplink resources for channel state information transmission. This 'cheap' feedback approach consumes far fewer uplink transmission resources compared to complete channel state feedback in OFDM, making it suitable for mobile scenarios where uplink resources are constrained.
3Ease of manufacture
If conventional fixed modulation format is used for static transmission, then system implementation is simple, but spectral efficiency and transmission capacity cannot be dynamically optimized for mobile users
Solution Approach 1:
The patent transforms the static fixed modulation format into a dynamic hybrid modulation scheme. The system continuously adapts the modulation format selection based on real-time channel conditions and terminal movement states, enabling dynamic optimization of spectral efficiency and transmission capacity while maintaining reasonable system complexity through the use of only two modulation formats.
Data Source
AI summary
The present invention discloses a capacity optimization method for a mobile optical wireless communication system and a communication method and system. The capacity optimization method includes the following steps: establishing a mobile channel impulse response model; calculating an electrical signal-to-noise ratio (SNR) of an output of a receiver; calculating bit error rate (BER) values of an optical wireless communication system in different candidate modulation formats according to the electrical SNR of the output of the receiver; selecting a first modulation format and a second modulation format from the different candidate modulation formats; determining quantities of chips in the first modulation format and the second modulation format in each data frame; and building a time domain hybrid modulation frame according to the quantities of chips in the first modulation format and the second modulation format, modulating data by using the time domain hybrid modulation frame, and performing data transmission.