Wireless Transmitter Phase Rotation for Multi-User Diversity
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Solution Overview
Problem
Conventional communication systems fail to achieve an adequate multi-user diversity effect due to limitations in allocated slot and receiver location.
Innovation Solution
A terminal apparatus with a channel estimating unit, antenna selecting/phase amount calculating unit, and phase rotating unit is used to select and rotate base station antennas based on channel estimation, improving communication state and achieving a favorable multi-user diversity effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional allocated slots are used in multicarrier transmission systems, then frequency diversity effect is obtained for broadcast/multicast channels, but multi-user diversity effect is insufficient for unicast signals
Solution Approach 1:
The patent applies dynamics by making the allocated slot configuration adaptable rather than fixed. The system dynamically determines optimal slot allocations based on real-time channel conditions and user requirements, allowing the same physical infrastructure to serve both broadcast and unicast traffic with optimized performance. This resolves the contradiction by enabling the system to adapt slot assignments to maximize multi-user diversity effect while maintaining frequency diversity when needed.
Solution Approach 2:
The patent utilizes parameter changes by modifying slot allocation parameters based on transmission type and channel conditions. For unicast signals, the system changes allocation parameters to narrow frequency blocks to enhance multi-user diversity, while for broadcast channels it uses wider frequency blocks for frequency diversity. This dynamic parameter adjustment resolves the technical contradiction by allowing the system to optimize for different performance goals as needed.
2Reliability
If fixed allocated slots are assigned to users, then system simplicity is maintained, but communication quality deteriorates due to inability to adapt to channel conditions
Solution Approach 1:
The patent implements feedback mechanisms where users report channel conditions and reception quality to the base station. This feedback information is used to dynamically adjust slot allocations and transmission parameters. The feedback loop enables the system to improve communication quality by adapting to changing channel conditions while maintaining manageable complexity through automated control algorithms.
Solution Approach 2:
The system applies self-service principles by enabling users to autonomously measure and report their own channel conditions and reception quality. This user-side self-assessment reduces the burden on the base station for complex centralized optimization, thereby improving communication quality while controlling overall system complexity through distributed intelligence.
3Reliability
If base station antennas transmit without phase rotation, then transmission simplicity is maintained, but multi-user diversity effect is insufficient
Solution Approach 1:
The patent applies parameter changes by introducing phase rotation as a controllable transmission parameter. The base station dynamically adjusts phase rotation angles for different base station antennas based on channel conditions and user locations. This parameter modification enhances the multi-user diversity effect by creating different signal phases at user locations, thereby improving communication reliability without requiring complete system redesign.
Solution Approach 2:
The system utilizes periodic action by implementing phase rotation in a structured, repeatable manner across different time slots and frequency blocks. The phase rotation patterns are applied periodically to different antenna combinations, creating predictable signal variations that enhance diversity effects. This periodic approach improves reliability while maintaining manageable complexity through systematic application of phase modulation.
Data Source
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Figure 2A~2B
Figure 3A~3C
AI summary
A wireless transmitter comprising: a plurality of transmission antennas; and a phase rotating unit which adds phase rotation to signals which are respectively input to the plurality of transmission antennas, wherein the phase rotating unit adds first phase rotation for controlling the maximum delay time between the plurality of transmission antennas and second phase rotation for controlling the phases of arbitrary antennas among the plurality of transmission antennas.