Multi-Stream Transmission Method for Flexible Modulation Selection
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Solution Overview
Problem
Current multi-carrier modulation techniques, such as OFDM, are not well-suited for sporadic low-power communications like MTC due to spectral spreading and complexity issues, while FBMC offers better spectral efficiency but is too complex for low-complexity devices like MTC, and there is a need for a flexible method to support various communication services like MBB, MTC, and V2X with low complexity and high spectral efficiency.
Innovation Solution
A multi-stream transmission method using linear frequency filtering with configurable coefficients and a common time-frequency transform to generate both conventional OFDM and FBMC modulations, allowing easy switching between different services and pre-equalizing phase changes to reduce inter-carrier interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If OFDM modulation is used for multi-carrier transmission, then ease of implementation and standard compatibility are improved, but spectral efficiency deteriorates due to spectral spreading
Solution Approach 1:
The patent dynamically selects between OFDM and FBMC modulation schemes based on service type requirements. For MBB services, OFDM is used for ease of implementation, while for MTC services, FBMC is selected to improve spectral efficiency. This dynamic adaptation resolves the contradiction by allowing each modulation scheme to be used where it is most appropriate.
Solution Approach 2:
The patent changes the modulation parameter (OFDM vs FBMC) according to the service type. By adjusting this parameter based on whether the service is MBB or MTC, the system optimizes both implementation ease and spectral efficiency for different communication scenarios.
2Quantity of substance
If FBMC modulation is used to improve spectral efficiency, then spectral efficiency is improved, but device complexity increases making it unsuitable for low-complexity MTC devices
Solution Approach 1:
The patent applies different modulation qualities to different service locations. FBMC with higher spectral efficiency is applied locally to MTC services where spectral resources are critical, while OFDM is applied to MBB services where implementation simplicity is prioritized. This local differentiation resolves the contradiction between spectral efficiency and device complexity.
Solution Approach 2:
The modulation scheme parameter is changed based on service type requirements. For MTC services, the parameter is set to FBMC to improve spectral efficiency, while for MBB services, it is set to OFDM to maintain low device complexity. This parameter adaptation resolves the technical contradiction.
3Adaptability or versatility
If separate transmission chains are used for different service types, then service-specific optimization is improved, but system complexity and resource utilization deteriorate
Solution Approach 1:
The patent creates a universal transmission chain that can handle multiple service types (MBB and MTC) through a single IFFT block. The system uses service-type-specific filtering and modulation parameter selection to optimize for different services while maintaining a common underlying structure, thereby achieving service-specific optimization without proportionally increasing system complexity.
Solution Approach 2:
The patent segments the transmission chain into service-specific filtering stages and a common IFFT stage. By separating the filtering function (which is service-dependent) from the core IFFT operation (which is common), the system achieves service-specific optimization while avoiding the need for completely separate transmission chains for each service type.
4Use of energy by moving object
If MTC devices use low power consumption mode, then power consumption is reduced, but communication reliability deteriorates for high-speed cellular communications
Solution Approach 1:
The patent changes the modulation scheme parameter based on service type. For MTC services, FBMC is used which provides better spectral efficiency and allows for more reliable low-power operation. For MBB services, OFDM is used which maintains high data rates and reliability. This parameter adaptation resolves the contradiction between power consumption and communication reliability.
Data Source
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AI summary
The present invention relates to a method for transmitting multiple communications of different types, in particular sporadic (MTC) or cellular (broadband) communication comprising symbols to be transmitted, corresponding to communication services implementing a modulation having M subcarriers of the FBMC-OQAM or OFDM-OQAM type. The method uses linear frequency filtering of a sequence of length N including symbols having L coefficients that are parametrizable according to the communication, L, N, and M being natural numbers, so as to generate N + L - 1 symbols, reducing out-of-band spurious emissions. Said method also uses, no matter what the communication is, a single frequency/time transform (IFFT) having a size M, where N < M. Indeed for sporadic communications (MTC) in a lower frequency band, the constraints on the out-of-band side-lobes are more stringent on the filter and FBMC modulation is thus better adapted.