QAM Signal Transmission in Filter Bank Multicarrier Systems
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Solution Overview
Problem
Existing Filter Bank Multicarrier (FBMC) communication systems face interference issues due to overlapping filtering of odd and even sub-carriers, limiting their ability to use Quadrature Amplitude Modulation (QAM) signals and resulting in inferior spectrum performance compared to OFDM systems.
Innovation Solution
The method involves spreading QAM signals into the frequency domain, intersecting and filtering them to prevent interference, and overlapping the filtered signals in the time domain, using complex domain filters to maintain orthogonality between sub-carriers, thereby enabling QAM-based MIMO techniques and reducing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If filtering signals of odd sub-carrier and even sub-carrier are overlapped in FBMC system, then spectrum efficiency is improved, but intrinsic interference occurs between adjacent sub-carriers
Solution Approach 1:
The patent divides QAM signals into multiple groups and processes different groups through different filtering paths. Even sub-carrier signals and odd sub-carrier signals are separated into distinct signal groups, each undergoing specific filtering operations. This segmentation prevents interference between adjacent sub-carriers while maintaining spectrum efficiency through controlled overlapping of filtered signals.
2Productivity
If QAM signals are transmitted in FBMC system with overlapping filters, then data transmission rate is improved, but signal orthogonality is lost
Solution Approach 1:
The patent applies different filtering characteristics to different sub-carrier groups. Even sub-carrier signals undergo one type of filtering while odd sub-carrier signals undergo another type of filtering. This local differentiation in filtering quality maintains orthogonality between adjacent sub-carriers while enabling QAM modulation for high-rate data transmission.
3Measurement precision
If complex domain filters are used for QAM signals in FBMC, then spectrum performance is improved, but system complexity increases
Solution Approach 1:
The patent segments the filtering process into distinct paths for even and odd sub-carrier groups. By processing these groups separately with appropriate complex domain filters and then combining the results, the system achieves high spectrum performance while managing complexity through modular processing architecture.
Data Source
AI summary
Disclosed is a 5G or pre-5G communication system to be provided for supporting a data transfer rate higher than that of a 4G communication system, such as LTE, and subsequent systems. The present invention relates to a method for transmitting and receiving a QAM signal in a filter bank-based multicarrier communication system, and an apparatus therefor. Particularly, the present invention provides an efficient transmission and reception method and apparatus capable of obtaining high performance in the transmission of a QAM signal without intrinsic interference in a multi-path delay channel environment in a filter bank-based multicarrier communication system. Accordingly, the present invention relates to a transmission method in a filter bank-based multicarrier (FBMC) communication system, and an apparatus therefor, the method comprising the steps of: spreading each of two QAM signals divided into a plurality of groups to a plurality of signals on a frequency axis; intersecting at least one signal, which is overlapped with a spread signal of an adjacent QAM signal among the plurality of spread signals, with the spread signal of the adjacent QAM signal; filtering, by each of the plurality of groups, the plurality of spread signals of which at least one signal has been intersected; and transmitting the plurality of filtered spread signals by being overlapped on a time axis.