Space Time Transmit Diversity With Selected Complex Conjugate Inputs
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Solution Overview
Problem
Current wireless communication systems, such as CDMA and TDMA, face challenges in improving signal-to-noise ratio (SNR) and reducing channel effects due to redundancy in space-time transmit diversity (STTD) systems and lack of orthogonality in multiple-input multiple-output (MIMO) systems, leading to interference and reduced data rates.
Innovation Solution
A wireless transmitter and receiver system that employs multiple space-time transmit diversity encoding with circuitry for forming complex conjugates of selected symbols before encoding and decoding, using multiple antennas to transmit and receive signals, and estimating channel effects to improve data rate and signal processing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If space-time transmit diversity (STTD) encoding is used to improve signal-to-noise ratio, then reliability is improved, but device complexity increases due to redundancy requirements
Solution Approach 1:
The patent applies partial conjugation where only selected symbols (every other symbol) undergo complex conjugation before STTD encoding, rather than all symbols. This partial action reduces the redundancy and complexity of the encoding process while maintaining the essential diversity benefits for improving signal-to-noise ratio and reliability.
2Productivity
If multiple-input multiple-output (MIMO) system is used to increase data rate, then productivity is improved, but object-generated harmful factors increase due to lack of orthogonality causing interference
Solution Approach 1:
The patent applies different processing to different symbol positions: selected symbols undergo complex conjugation while non-selected symbols do not. This local differentiation creates orthogonality between signals from different antennas at specific time instances, reducing interference while maintaining high data rates through multiple simultaneous transmissions.
Data Source
AI summary
A transmitter comprising circuitry (14) for converting input bits to a plurality of symbols; and circuitry (24x) for forming a complex conjugate of signals corresponding to selected ones of the plurality of symbols. The selected ones of the plurality of symbols consist of signals corresponding to some and less than all the plurality of symbols. The transmitter also comprises circuitry (28x) for space time encoding both the signals corresponding to the selected ones of the plurality of symbols and signals corresponding to non-selected ones of the plurality of symbols. Lastly, the transmitter comprises a plurality of transmit antennas (TATx) coupled to transmit signals in response to the circuitry for space time encoding.