OFDM Receiver Window Timing Optimization for ISI Reduction
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Solution Overview
Problem
Existing OFDM receiving apparatuses face challenges in improving reception characteristics due to Inter Symbol Interference (ISI) and Inter Carrier Interference (ICI) caused by delay spreads exceeding the cyclic prefix (CP) length, leading to suboptimal signal power recovery and residual interference.
Innovation Solution
A receiving apparatus and method that determine Fourier transform window start and end timings based on signal-to-interference power ratio and signal power, using a window timing selection unit to optimize the Fourier transform processing and reduce residual interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cyclic prefix length is increased to prevent ISI and ICI caused by delay spread, then reception characteristics are improved, but transmission efficiency deteriorates due to increased overhead
Solution Approach 1:
The patent dynamically adjusts the FFT window timing based on detected channel delay spread characteristics rather than using a fixed cyclic prefix length. The window start timing is shifted according to the actual delay spread measured from the received signal, allowing the system to adapt to varying channel conditions and optimize the balance between interference suppression and transmission efficiency.
2Device complexity
If conventional FFT window timing is used without optimization, then device complexity is low, but signal power recovery is insufficient and residual interference remains
Solution Approach 1:
The patent performs preliminary detection of channel delay spread characteristics and determines optimal FFT window timing before actual data reception. By pre-calculating the appropriate window start timing based on channel conditions, the system prepares the optimal reception parameters in advance, ensuring maximum signal power recovery without adding complex real-time processing during data reception.
Solution Approach 2:
The patent skips the traditional approach of using fixed cyclic prefix timing and directly applies optimized FFT window timing based on detected channel characteristics. This allows the receiver to rush through the interference-prone period by aligning the FFT window to start after the main delay spread components, thereby reducing residual interference while maintaining simple receiver architecture.
3Measurement precision
If FFT window timing is optimized based on delay profile, then signal power recovery improves, but device complexity increases due to additional processing units
Solution Approach 1:
The patent enables the receiver to self-determine optimal FFT window timing by detecting delay spread characteristics from the received signal itself. The system uses built-in processing to analyze the channel impulse response and automatically adjust window timing without requiring external control or complex additional hardware, thereby achieving improved signal recovery with minimal increase in device complexity.
Data Source
AI summary
The present invention improves reception characteristics of a receiving apparatus based on OFDM. The receiving apparatus includes: a window timing selection unit that determines Fourier transform window start and end timings for a received signal(s) based on OFDM, based on a signal-to-interference power ratio and signal power in a Fourier transform window; and a Fourier transform unit that performs Fourier transform on the received signal(s) in accordance with the Fourier transform window start and end timings outputted by the window timing selection unit.