Multicarrier Signal Precoding for Self-Interference Mitigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing solutions for mitigating self-interference in FDD systems either distort the signal or increase energy consumption, which is not acceptable in ultra-reliable communications.
Innovation Solution
A precoding technique using a near-orthogonal space to suppress out-of-band subcarriers, with a channel estimation mechanism to facilitate receiver equalization, without distorting the signal or increasing energy consumption, by employing a mapping function based on frequency offset and transfer matrix analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If RF analog filters are used to filter out the transmit signal, then self-interference is reduced, but device area and energy consumption increase
Solution Approach 1:
The patent replaces the mechanical RF analog filter system with a digital signal processing approach using precoding in the frequency domain. Instead of using physical filters to suppress sidelobes, the system applies a precoding matrix to the data symbols before OFDM modulation, achieving sidelobe suppression through mathematical transformation rather than physical filtering. This substitution eliminates the need for complex RF filter hardware and reduces energy consumption.
2Object-generated harmful factors
If data symbols are modified to suppress OOB emissions, then out-of-band emissions are reduced, but signal distortion and EVM increase
Solution Approach 1:
The patent applies precoding as a preliminary action before OFDM modulation and transmission. By pre-multiplying the data symbols with a precoding matrix designed to suppress sidelobes, the system proactively shapes the spectral characteristics of the transmitted signal. This preliminary transformation ensures that OOB emissions are suppressed at the source without requiring post-processing or modification that would distort the signal, thereby maintaining signal accuracy while reducing harmful emissions.
3Productivity
If transmit and receive frequencies are placed close to each other, then spectral efficiency increases, but self-interference worsens
Solution Approach 1:
The patent changes the spectral parameters of the transmit signal through precoding to suppress sidelobes and OOB emissions. By applying a precoding matrix that modifies the amplitude and phase relationships among subcarriers, the system reshapes the spectral envelope to reduce energy leakage into adjacent frequency bands. This parameter transformation allows the receive frequency to be placed closer to the transmit frequency without suffering from strong sidelobe interference, thereby enabling higher spectral efficiency while controlling self-interference.
Data Source
AI summary
The disclosure relates to a transmission device, comprising: a processor configured: to generate a multicarrier signal based on a combination of data symbols and reference symbols, wherein the multicarrier signal comprises a first plurality of inband subcarriers and a second plurality of out-of band (OOB) subcarriers, and to precode the multicarrier signal based on a mapping function with respect to the first plurality of inband subcarriers and the second plurality of out-of band subcarriers, wherein the mapping function is configured to mitigate the OOB subcarriers.