FBMC Transmitter Phase Amplitude Pre-Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
FBMC transmission/reception systems face challenges due to the real character of modulation symbols, which complicates channel estimation and receiver implementation, especially in mobile terminals, and existing solutions like FFT-FBMC have drawbacks such as amplitude variations and complex receiver structures.
Innovation Solution
A variant of the FBMC system with phase and amplitude pre-compensation at the transmitter, using Hadamard products to compensate for phase and amplitude rotations, simplifying the receiver structure to a single FFT, and allowing for direct channel estimation and equalization like conventional OFDM systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If FBMC modulation is used to improve out-of-band rejection ratio, then spectral efficiency is improved, but the real character of modulation symbols complicates channel estimation and receiver implementation
Solution Approach 1:
The patent applies preliminary phase and amplitude compensation to the modulation symbols before transmission. By pre-compensating the symbols at the transmitter side, the receiver structure is simplified and can be reduced to a single FFT operation, making the system more suitable for mobile terminals while maintaining the out-of-band rejection benefits of FBMC
Solution Approach 2:
The patent modifies the modulation symbols by applying phase and amplitude transformations through Hadamard products. This parameter change compensates for the intrinsic interference and amplitude variations introduced by FBMC modulation, enabling simpler receiver implementation with direct channel estimation capabilities
2Device complexity
If FFT-FBMC is used to simplify receiver structure, then receiver complexity is reduced, but amplitude variations and complex receiver structures still remain
Solution Approach 1:
The patent performs preliminary amplitude compensation on the modulation symbols before transmission. By pre-adjusting the amplitude parameters at the transmitter, the system eliminates amplitude variations at the receiver side, achieving both simple receiver structure and accurate amplitude control without the drawbacks of conventional FFT-FBMC approaches
3Ease of operation
If conventional OFDM is used to simplify implementation, then receiver structure is simple, but spectral efficiency is reduced due to guard interval insertion
Solution Approach 1:
The patent changes the modulation parameters by applying phase and amplitude transformations to the symbols. This allows the system to achieve OFDM-like simple receiver implementation (single FFT) while maintaining FBMC's high spectral efficiency by eliminating the need for long guard intervals through intrinsic interference elimination
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to an FBMC transmit/receive system in which phase (210) and amplitude (220) pre-compensation is performed at the transmitter on a block of modulation symbols. The compensated symbol block is segmented (230) into M sub-blocks equal to the number of carriers in an FBMC modulator. The sub-blocks are divided into N/2 size vectors and padded (240) with isolation zeros to form N-size padded vectors. Each of these M padded vectors is subjected to an IFFT (250) to produce time sequences to which cyclic prefixes and suffixes (260) are added. The resulting cyclic sequences are then provided to the M input channels of the FBMC modulator. The receive symbols can be recovered at the receiver using a simple NM/2 size FFT.