OFDM Transmitter Dynamic Windowing for Out-of-Band Radiation Suppression
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Solution Overview
Problem
Existing wireless communication methods using OFDM or OFDMA in strict transmission spectrum regulation bands, such as white spaces, face challenges in suppressing out-of-band radiation without reducing transmission signal power, leading to increased costs and reduced coverage areas.
Innovation Solution
A wireless transmitter and receiver system that analyzes RF circuit characteristics and multipath delays to dynamically set windowing functions, windowing durations, guard intervals, and transmission power for OFDM symbols, allowing for separate adjustments in preamble and data sections, thereby effectively suppressing out-of-band radiation while maintaining signal strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If waveform shaping by windowing is used to suppress out-of-band radiation, then transmission spectrum mask compliance is improved, but transmission signal power must be reduced leading to reduced coverage area
Solution Approach 1:
The patent dynamically adjusts windowing parameters (windowing function type, windowing duration, roll-off coefficient) based on RF circuit characteristics and communication environment to achieve optimal out-of-band suppression without excessive power reduction. This allows adaptation to different hardware characteristics and transmission conditions.
Solution Approach 2:
The system dynamically selects windowing functions and parameters based on detected multipath delay, RF circuit characteristics, and desired transmission power levels. This dynamic adaptation enables the system to maintain coverage area while complying with spectrum masks by optimizing the windowing approach for each transmission condition.
2Object-affected harmful factors
If convolution filter is applied to transmission signal on baseband to suppress out-of-band radiation, then transmission spectrum mask compliance is improved, but device complexity increases
Solution Approach 1:
The patent adjusts digital filter parameters (filter type, cutoff frequency, order) based on RF circuit characteristics and desired spectrum mask compliance. By dynamically tuning filter parameters rather than using fixed complex filtering, the system achieves out-of-band suppression with manageable device complexity.
Solution Approach 2:
The system dynamically selects and adjusts digital filter characteristics based on detected communication conditions and RF circuit measurements. This allows the filter complexity to be optimized for each situation, using simpler filters when sufficient and more complex filters only when necessary for spectrum mask compliance.
3Object-affected harmful factors
If transmission signal power is reduced to comply with transmission spectrum mask regulation, then out-of-band radiation is suppressed, but coverage area is reduced
Solution Approach 1:
The patent optimizes windowing and filtering parameters to achieve the minimum necessary out-of-band suppression for spectrum mask compliance, thereby minimizing power reduction requirements. By tuning parameters like windowing duration and filter cutoff frequency, the system maintains maximum permissible transmission power while meeting regulatory requirements.
Solution Approach 2:
The system dynamically determines the appropriate transmission power level based on RF circuit characteristics, selected windowing parameters, and filter settings. This allows the transmission power to be maximized within regulatory limits for each specific hardware and environmental configuration, preserving coverage area.
4Object-affected harmful factors
If high-performance radio frequency conversion function is used to satisfy strict transmission spectrum mask regulation, then out-of-band radiation is suppressed, but device cost increases
Solution Approach 1:
The patent adjusts windowing and filtering parameters based on the actual RF circuit characteristics of the specific hardware implementation. This allows standard, lower-cost RF components to achieve spectrum mask compliance through software-based parameter optimization rather than requiring expensive high-performance hardware.
Solution Approach 2:
The system replaces hardware-based spectrum suppression mechanisms with software-based windowing and filtering parameter adjustment. By using programmable parameter changes instead of fixed high-performance hardware, the system reduces device cost while achieving the required out-of-band radiation suppression.
Data Source
AI summary
In order to suppress out-of-band radiation within a range of a spectrum mask regulation without reducing transmission signal power or the like even when a wireless communication is performed in a white space by using OFDM or the like, the present invention is characterized by including an RF circuit characteristic analysis unit, a multipath delay detection unit, a digital filter setting unit, and a transmission power setting unit and further including: a windowing function/windowing duration selection unit configured to select a windowing function and a windowing duration based on the analysis result by the RF circuit characteristic analysis unit, the detection result by the multipath delay detection unit, and the setting by the digital filter setting unit and the transmission power setting unit; a guard interval duration selection unit configured to select a guard interval duration; and a transmission power selection unit configured to select transmission power.