RQAM Modulation for Multipath Diversity Without Multiple Antennas
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Solution Overview
Problem
Conventional methods for improving communication characteristics in multipath environments require multiple antennas and RF units, increasing costs and reducing communication speed, which is detrimental in systems with many users, especially those requiring real-time operations.
Innovation Solution
A transmission device that uses a Rotated Quadrature Amplitude Modulation (RQAM) system to divide signals into in-phase and orthogonal components, mapping them using a specific matrix-based system to achieve diversity effects across multiple sub-carriers, thereby improving communication characteristics without the need for multiple antennas or RF units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If receiving or transmitting diversity is performed using multiple antennas and RF units, then communication characteristics are improved, but device cost increases
Solution Approach 1:
The invention divides a single RF unit's signal processing into multiple virtual channels through signal separation technology. The single RF unit is segmented into multiple logical transmission paths that simulate the effect of multiple physical antennas, achieving diversity without requiring multiple physical RF units.
Solution Approach 2:
The invention creates virtual copies of transmission channels through signal processing. By separating and processing signals into multiple streams within a single RF unit, it replicates the functionality of multiple physical antennas, providing diversity effect without the cost of additional hardware.
2Reliability
If multiple repeated transmissions and error corrections are performed, then communication reliability is improved, but communication speed decreases
Solution Approach 1:
The invention performs error correction coding in advance before transmission. By pre-processing the signal with error correction codes and separating it into multiple virtual channels, the system achieves reliable communication without requiring multiple repeated transmissions, thus maintaining high communication speed.
3Ease of manufacture
If the same modulation system is assigned to all sub-carriers, then system implementation is simplified, but communication characteristics deteriorate in multipath environment
Solution Approach 1:
The invention applies different modulation characteristics to different sub-carriers through signal separation. By dividing the signal into multiple virtual channels with different modulation properties, each sub-carrier can be optimized for its specific frequency characteristics, improving performance in multipath environments while maintaining reasonable implementation complexity.
Data Source
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AI summary
To include an RQAM modulating unit 11 that has an S/P that divides a transmitting signal indicating information to be transmitted into a first signal and a second signal, a mapping unit that maps the first signal into a first in-phase component and a second in-phase component and the second signal into a first orthogonal component and a second orthogonal component by a predetermined mapping system, and a P/S that generates a first modulated signal including the first in-phase component and the first orthogonal component and a second modulated signal including the second in-phase component and the second orthogonal component, IFFT 12 that transmits the first modulated signal and the second modulated signal, a DAC 13, an LPF 14, a Mixer 15, a BPF 16, and a LOCAL 18.