Time-Domain Windowing Circuit for OFDM Out-of-Band Emission Suppression
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Solution Overview
Problem
Existing methods for suppressing out-of-band emission (OOBE) in OFDM and DFTs-OFDM schemes face challenges, including increased circuit complexity and communication quality deterioration due to strict bandwidth limitation and long window transition lengths.
Innovation Solution
A transmission device and method utilizing a time-domain windowing process where a transmission symbol is multiplied by a pre-convolved arbitrary filter, generating a new window function to achieve effective OOBE suppression with reduced circuit scale and improved communication quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If strict bandwidth limitation by a filter is performed, then OOBE suppression effect is improved, but the number of multipliers involved in convolution processing increases, leading to increased circuit scale and calculation amount
Solution Approach 1:
The filter is pre-convolved with the time window function during an offline preparation phase to generate a pre-computed time window. This preliminary action transfers the computational burden from the real-time transmission path to the offline preparation phase, eliminating the need for complex real-time filtering operations while maintaining OOBE suppression effectiveness.
Solution Approach 2:
The invention merges the filter function and the time window function into a single pre-computed time window. By combining these two separate processing stages into one integrated component, the system achieves both bandwidth limitation and discontinuity smoothing without requiring separate filter and windowing operations, thereby reducing circuit complexity.
2Object-generated harmful factors
If a window transition length is increased to suppress OOBE by smoothing discontinuity between symbols, then OOBE suppression effect is improved, but communication quality deteriorates
Solution Approach 1:
The invention changes the parameters of the time window function by incorporating filter characteristics into the window design. This parameter modification allows the system to achieve effective OOBE suppression with optimized window transition lengths that balance both suppression performance and communication quality, avoiding the degradation associated with excessively long transition lengths.
3Reliability
If a window transition length is shortened to improve communication quality, then communication quality is improved, but OOBE suppression effect decreases
Solution Approach 1:
The invention creates a composite time window function that integrates the characteristics of both filtering and windowing. This composite approach combines the spectral shaping properties of filters with the discontinuity smoothing properties of time windows, enabling effective OOBE suppression even with shorter transition lengths that preserve communication quality.
Data Source
AI summary
A transmission device including a time-domain windowing processing circuit to which a transmission symbol is input and in which the transmission symbol is multiplied by a time window. As the time window, a result of pre-convolving an arbitrary filter into an arbitrary time window is used.