Radio Transmission Device Dynamic Spatial Multiplexing Adaptation
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Solution Overview
Problem
Conventional radio transmission devices using MIMO technology face reduced throughput due to the need to either transmit the same or different signals from multiple antennas, leading to inefficient use of propagation paths and increased error rates when path conditions are poor.
Innovation Solution
A radio transmission device that dynamically allocates transmission signals to sub-carriers based on propagation path characteristics, allowing for spatial multiplexing only where paths are good, and transmitting the same signals without multiplexing where paths are poor, with the ability to adjust transmission power and symbol allocation to optimize throughput and error rate distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spatial multiplexing is performed using different signals from multiple antennas, then transmission capacity is improved, but error rate increases when propagation path conditions are poor
Solution Approach 1:
The patent dynamically switches between spatial multiplexing mode (different signals from multiple antennas) and spatial diversity mode (same signal from multiple antennas) based on real-time propagation path conditions. The system monitors channel quality and adapts the transmission mode accordingly, transitioning from high-capacity multiplexing when paths are good to reliable diversity transmission when paths deteriorate, thus resolving the contradiction between transmission capacity and error rate
Solution Approach 2:
The patent changes the transmission parameter (signal differentiation) based on propagation path conditions. When path conditions are favorable, the system uses different signals for multiplexing to maximize capacity. When path conditions worsen, the system changes to transmitting the same signal from multiple antennas to improve reliability, effectively adjusting the transmission parameter to match channel conditions and resolve the capacity-reliability tradeoff
2Reliability
If the same signal is transmitted from multiple antennas, then error rate is reduced through diversity, but throughput is halved due to lack of spatial multiplexing
Solution Approach 1:
The system dynamically adapts the transmission mode based on propagation path conditions. When paths are good, it uses spatial multiplexing for high throughput. When paths deteriorate, it switches to spatial diversity for reliability. This dynamic adaptation allows the system to optimize the tradeoff between throughput and error rate protection according to real-time channel conditions
Solution Approach 2:
The patent changes the transmission parameter (whether to use different or same signals) based on channel conditions. This parameter change enables the system to switch between multiplexing mode for high throughput and diversity mode for error protection, resolving the contradiction between throughput and reliability
3Adaptability or versatility
If separate systems are provided for OFDM signal selection, then transmission mode flexibility is improved, but device complexity increases
Solution Approach 1:
The patent merges the control functions into a single transmission device that can handle both spatial multiplexing and spatial diversity modes. Instead of using separate systems for different transmission modes, the invention integrates the mode selection and signal processing functions in one device, reducing overall system complexity while maintaining transmission flexibility
Solution Approach 2:
The transmission device is designed with universal functionality to handle multiple transmission modes (spatial multiplexing and spatial diversity) within a single system. The device can adaptively switch between modes based on channel conditions, eliminating the need for separate dedicated systems for each mode and thereby reducing device complexity
Data Source
AI summary
To obtain maximum throughput in accordance with characteristics of a propagation path, a radio transmission device having a plurality of transmitting antennas (18a, 18b) for transmitting a transmission signal in units of sub-carriers by performing spatial multiplexing or without performing spatial multiplexing is provided that includes a sub-carrier modulation part 11 modulating the input transmission signal for each sub-carrier, a transmission signal allocation part 13 allocating the transmission signal modulated for each of the sub-carriers to each of the transmitting antennas, and a transmission control part 12 that determines a multiplexing number for performing spatial multiplexing for each sub-carrier based on information received from another radio communication device as an opposite party, and outputs the determined multiplexing number to the sub-carrier modulation part and the transmission signal allocation part.