Space-Time Block Coder With Phase Rotation For Full Diversity And Rate
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Solution Overview
Problem
Current space-time block coding (STBC) techniques fail to achieve full diversity and full rate simultaneously in mobile communication systems using two transmit (Tx) antennas, leading to reduced data rate and performance degradation due to channel changes in fast fading channels.
Innovation Solution
A new STBC apparatus and method that uses a coding matrix [a×s1+j×b×s4, b×s2+a×s3, a×s2-b×s3, j×b×s1+a×s4] with constants a and b related by a2+b2=½, where θ is optimized to maximize coding gain, allowing for full diversity and full rate transmission through two Tx antennas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional STBC schemes are used with two Tx antennas, then diversity gain is improved, but data rate is reduced and full rate is not achieved
Solution Approach 1:
The patent changes the parameters of the coding matrix by introducing phase rotation angles (θ1, θ2, θ3, θ4) and complex coefficients (α, β, γ, δ) that satisfy specific constraints. This allows the system to achieve full diversity gain while maintaining full rate operation. The coding matrix uses these parameter changes to create orthogonal designs that maximize both reliability and productivity.
2Reliability
If conventional STBC schemes are used with two Tx antennas, then coding gain is improved, but performance degrades in fast fading channels due to channel changes
Solution Approach 1:
The patent employs dynamic phase rotation angles (θ1, θ2, θ3, θ4) in the coding matrix that can be optimized for different channel conditions. The use of complex coefficients with specific constraints allows the system to adapt to fast fading channels while maintaining coding gain. This dynamic approach ensures performance stability despite rapid channel changes.
3Productivity
If higher order modulation is used to increase data rate, then productivity is improved, but error rate increases due to reduced coding gain
Solution Approach 1:
The patent changes the parameters of the coding matrix by introducing phase rotation angles and complex coefficients that maximize coding gain. This allows the system to achieve full diversity and full rate simultaneously, reducing the error rate while maintaining high data rate through higher order modulation. The parameter optimization ensures that coding gain is maximized for the given modulation scheme.
Data Source
AI summary
An apparatus and method for full-diversity, full-rate space-time block coding in a transmitter using two Tx antennas are provided. An input symbol sequence is STBC-encoded in a predetermined method and transmitted through the two Tx antennas.