Frequency Domain Linear Precoding for MIMO-FBMC Stream Separation
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Solution Overview
Problem
MIMO-FBMC systems are more complex than MIMO-OFDM systems due to the need for orthogonality in the complex plane to eliminate intersymbol interference, requiring complex precoding methods to guarantee stream separation and absence of interference between sub-channels.
Innovation Solution
A MIMO-FBMC system implementing a simple linear precoding method in the frequency domain, where data streams are spread over adjacent subcarriers and filtered using a prototype filter, followed by IFFT and spectral despreading, allowing for efficient separation of streams without introducing additional interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex precoding methods are used to guarantee stream separation and absence of interference between sub-channels in MIMO-FBMC systems, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent extracts the precoding operation from the time domain to the frequency domain, where it can be performed independently on each subcarrier. This separation allows the precoding function to be isolated and simplified, avoiding the complex time-domain operations required in conventional MIMO-FBMC systems while maintaining stream separation and interference cancellation.
Solution Approach 2:
The patent changes the domain parameter from time to frequency, transforming the precoding operation. By performing precoding in the frequency domain using FFT-based operations, the system achieves the same reliability goals with significantly reduced computational complexity, as frequency-domain operations can be efficiently implemented using standard FFT algorithms.
2Productivity
If FBMC modulation is used to achieve better spectral localization and out-of-band rejection, then productivity is improved, but device complexity increases compared to OFDM
Solution Approach 1:
The patent merges MIMO precoding with FBMC modulation by integrating the precoding operation into the FBMC signal generation process in the frequency domain. This combination allows the system to achieve both the spectral efficiency benefits of FBMC and the stream separation capabilities of MIMO precoding within a unified framework, avoiding the need for separate complex processing stages.
Data Source
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Figure 3A~3B
AI summary
The invention relates to a linear precoding MIMO-FBMC transmitter/receiver implemented in the frequency domain. In one transmitter-level embodiment, the linear precoding (5251, ..., 525 kN) is performed after filtering and spectral spreading, before IFFT and FBMC symbol combination in the time domain, such that the precoding does not introduce interference between the data streams. In a second embodiment, the linear precoding can be combined with beamforming at the transmitter or receiver so as to spatially separate the data streams.