Wireless Communication Apparatus Guard Interval Elimination
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Solution Overview
Problem
Existing radio communication systems face reduced data transmission rates due to the need for guard intervals in frequency domain equalization, which also degrade Bit Error Rate (BER) characteristics in broadband mobile communications.
Innovation Solution
A radio communication apparatus and method that performs fast Fourier transform on received signals without guard intervals, followed by frequency domain equalization and inverse fast Fourier transform, allowing for the selection of signal sequences to minimize interference and maintain good BER characteristics without the need for guard intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If guard intervals are inserted in frequency domain equalization, then BER characteristics are improved, but data transmission rate decreases
Solution Approach 1:
The patent extracts and removes the guard interval from the conventional FDE structure, processing only the essential data-carrying symbols. By applying FDE directly to symbols without guard intervals and using selective signal processing to eliminate ISI, the system achieves both high transmission efficiency and good BER characteristics.
Solution Approach 2:
The patent changes the processing parameters by removing the guard interval length parameter and adjusting the FFT block size to match the symbol block size. This parameter change enables the system to achieve maximum transmission rate while maintaining BER performance through alternative ISI cancellation methods.
2Object-affected harmful factors
If guard intervals are provided in FDE, then ISI is reduced, but transmission efficiency decreases
Solution Approach 1:
The patent converts the harmful ISI effect into a manageable parameter by using the known channel impulse response to predict and subtract ISI components from the received signal. This approach transforms ISI from an unavoidable distortion into a compensable interference, eliminating the need for guard intervals while maintaining signal quality.
Solution Approach 2:
The patent performs preliminary estimation of the channel impulse response and predicted ISI components before the main equalization process. By preparing these reference signals in advance, the system can efficiently cancel ISI during symbol processing without requiring additional guard interval time.
3Reliability
If MLSE equalization is used, then BER characteristics are improved, but calculation complexity increases exponentially
Solution Approach 1:
The patent segments the equalization process into two independent stages: channel impulse response estimation and signal detection. By separating these functions and using FDE for the detection stage, the system avoids the exponential complexity of MLSE while maintaining BER performance through the combination of channel estimation and frequency domain equalization.
Solution Approach 2:
The patent replaces the time-domain MLSE mechanical processing with frequency-domain FDE processing. By transforming the equalization operation to the frequency domain using FFT, the system reduces computational complexity from exponential to linear scale while achieving similar or better BER characteristics.
Data Source
AI summary
A wireless communication apparatus capable of enhancing the transmission efficiency, while maintaining a good BER characteristic. In this apparatus, a setting part (13) sets, based on the maximum delay amount of a delayed wave and also based on the expansion of impulse response of FDE, an FFT part (14) to establish an FFT section of Nc symbol, and also sets a selecting part (17) to establish a selection section of Nc−2M−Δ symbol that is shorter than the FFT section. The setting part (13) also sets the start points of FFT and selection sections established at this time for such timings that they are shifted by Nc−2M−Δ symbol from the start points of the FFT and selection sections previously established. It should be noted that the maximum delay amount of the delayed wave is Δ symbol, the expansion of impulse response of FDE is plus/minus M symbols, and the symbol block length is Nc.