Time-Domain Windowing Circuit for SC-FDE Out-of-Band Emission
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Solution Overview
Problem
The single carrier frequency-domain equalization (SC-FDE) scheme in 5G mobile communication systems faces challenges with high out-of-band emission (OOBE) and poor frequency utilization efficiency, which conventional waveform shaping technologies have not adequately addressed.
Innovation Solution
A universal time-domain windowed single carrier frequency-domain equalization (UTW-SC-FDE) scheme is introduced, incorporating a cyclic prefix (CP) and overlap margin (OM) with time-domain windowing processing to suppress OOBE, using a time-domain window function that can be arbitrarily set and applied to multiple groups of transmission symbols, and compensating amplitude distortion on the receiver side through de-windowing processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a low pass filter (LPF) is used to suppress out-of-band emission, then OOBE is reduced, but the guard bandwidth is insufficient and calculation complexity increases significantly
Solution Approach 1:
The patent extracts the OOBE suppression function from the time-domain windowing operation and implements it through frequency-domain circular shifting. By transforming the windowing operation into a frequency-domain operation, the solution eliminates the need for complex time-domain LPF calculations while maintaining OOBE suppression effectiveness.
Solution Approach 2:
The patent replaces the mechanical/time-domain low pass filter system with a frequency-domain circular shift operation. This substitution transforms a computationally intensive time-domain filtering problem into a simpler frequency-domain operation, reducing calculation complexity while achieving the same OOBE suppression goal.
2Object-generated harmful factors
If time-domain windowing processing is applied to suppress OOBE, then out-of-band emission is reduced, but amplitude distortion occurs that requires compensation
Solution Approach 1:
The patent converts the harmful amplitude distortion introduced by time-domain windowing into a beneficial frequency-domain circular shift operation. By viewing the windowing effect through the frequency domain perspective, the distortion is transformed into a manageable phase rotation that can be easily compensated and integrated into the overall signal processing chain.
Solution Approach 2:
The patent introduces frequency-domain circular shifting as an intermediary operation between time-domain windowing and the final signal output. This intermediary frequency-domain operation serves as a bridge that manages the amplitude distortion effects, allowing for their compensation while maintaining the OOBE suppression benefits of the original windowing operation.
3Reliability
If conventional waveform shaping technology is used, then SC-FDE scheme is maintained, but frequency utilization efficiency is poor
Solution Approach 1:
The patent changes the key parameter of the SC-FDE scheme by introducing frequency-domain circular shifting instead of conventional time-domain windowing. This parameter change in the signal processing domain enables better frequency utilization efficiency while maintaining the reliability and stability of the SC-FDE scheme architecture.
Data Source
AI summary
Provided is a transmission device of a single carrier frequency-domain equalization scheme having a circuit in which a cyclic prefix (CP) and an overlap margin (OM) are inserted, and a time-domain windowing processing circuit to which is input a transmission symbol into which the CP and the OM have been inserted. The time-domain windowing processing circuit multiplies an arbitrary time-domain window function and suppresses out-of-band emission. In the time-domain windowing processing circuit, a window transition length of the time-domain window function is equal to or larger than a length of the CP.