Real-Type Space-Time Coding for OFDM/OQAM Multi-Antenna Systems
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Solution Overview
Problem
Current OFDM/OQAM modulation systems with multiple antennas face challenges in combating interference due to spatial interference, leading to increased noise levels and unacceptable bit error rates, making it difficult to use Alamouti schemes effectively.
Innovation Solution
A transmission method employing real-type space-time coding with a coding matrix for OFDM/OQAM modulation, distributing symbols in time-frequency blocks of at least three symbols, ensuring consistent neighbors within blocks, and using channel coding with different error correction codes for edge symbols to combat interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Alamouti schemes are used in OFDM/OQAM modulation systems with multiple antennas, then spatial diversity can be exploited, but interference between symbols increases leading to unacceptable bit error rates
Solution Approach 1:
The transmission block is segmented into multiple sub-blocks, each processed independently with its own precoding matrix. This segmentation allows the system to manage interference locally within each sub-block rather than across the entire block, reducing the cumulative interference effect that causes high bit error rates in conventional Alamouti schemes.
Solution Approach 2:
Different precoding matrices are applied to different sub-blocks, creating local variations in the transmission characteristics. This local quality approach allows the system to optimize each sub-block independently, managing interference patterns differently across various parts of the transmission to overall reduce symbol interference.
2Productivity
If multiple antennas transmit simultaneously to increase transmission capacity, then spatial diversity is improved, but spatial interference increases leading to increased noise levels
Solution Approach 1:
The system changes the parameters of the transmitted signal by applying different precoding matrices to different sub-blocks. This parameter variation allows multiple antennas to transmit simultaneously with different characteristics, enabling the receiver to distinguish between signals from different antennas and reducing spatial interference while maintaining high transmission capacity.
Data Source
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AI summary
The present invention relates to a method of transmitting a multi-carrier signal intended to be implemented by a system with Nt transmit antennas, where Nt is greater than or equal to 2, Nr receive antennas, where Nr is greater than or equal to 1, of the type for distributing symbols before transmission into a time-frequency plan and for implementing an OFDM/OQAM modulation, in which the distributing (2) of the symbols is performed on blocks of determined size (4) nt.nf where nt ³ 3 and nj ³ 3. The method comprises a space-time coding (3) of real type by a space-time coder per block of blocks of coding matrix Nt ´ N and of efficiency Nc/N which are determined so as to generate Nt coded sequences of N blocks of symbols of an input sequence of Nc blocks of symbols.