Adjustable Transmit Diversity Frequency Spacing
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Solution Overview
Problem
Conventional phase sweeping transmit diversity techniques with fixed sweeping frequency spacing raise signal energy for non-fading channels, reducing network capacity.
Innovation Solution
Adjusting the sweeping frequency spacing based on measurements of fading and other impairments in the transmission path to dynamically optimize transmit diversity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed sweeping frequency spacing is used in PSTD, then fading resistance is improved, but network capacity is reduced due to increased Ec/Io for non-fading channels
Solution Approach 1:
The patent applies dynamics by transitioning from fixed sweeping frequency spacing to variable sweeping frequency spacing that adapts to channel conditions. The base station adjusts the sweeping frequency spacing dynamically based on feedback from the mobile station about detected fading conditions, allowing the system to optimize between fading resistance and network capacity depending on current channel state
Solution Approach 2:
The patent applies parameter changes by modifying the sweeping frequency spacing parameter based on channel conditions. When fading is detected, the sweeping frequency spacing is increased to improve fading resistance; when no fading is present, the spacing is decreased or eliminated to maintain network capacity, thus dynamically adjusting this key parameter to resolve the contradiction
2Reliability
If sweeping frequency spacing is increased to combat fading, then reliability is improved, but signal energy consumption increases
Solution Approach 1:
The patent applies parameter changes by adjusting the sweeping frequency spacing based on detected fading conditions. The base station receives feedback from the mobile station about channel conditions and modifies the sweeping frequency spacing accordingly - increasing it only when fading is detected to maintain reliability, and reducing or eliminating it during non-fading conditions to conserve signal energy
Data Source
AI summary
Systems and methods for adjustable transmit diversity (adjustable PSTD) are provided. A base station transmits information to a mobile station over two antennas. Using information received from the mobile station related to channel conditions, the base station can adjust a frequency offset between the information transmitted over the two antennas.