OFDM Reception Phase Drift Correction via Pilot Segmentation
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Solution Overview
Problem
The MISO method for terrestrial digital broadcasts faces challenges in accurately demodulating signals due to multipath interference, particularly in accurately estimating phase differences between transmission channels, which affects the accuracy of demodulation processing.
Innovation Solution
A reception apparatus and method that acquire OFDM signals from multiple transmission apparatuses, calculate correction values using either in-phase or out-of-phase pilot signals, and correct the drift amount of the OFDM signal to enhance demodulation accuracy, utilizing sum and difference pilot signals to determine the appropriate phase estimation based on transmission channel status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MISO method is used to transmit signals from multiple antennas, then signal transmission reliability is improved, but phase estimation accuracy deteriorates due to multipath interference
Solution Approach 1:
The patent segments the composite signal from multiple transmission antennas into individual antenna signals through separate signal paths. Each antenna's signal is processed independently through correlation operations with pilot signals, allowing separate phase estimation for each path before combining the results. This segmentation enables accurate phase estimation despite multipath interference by treating each transmission path individually.
Solution Approach 2:
The patent introduces pilot signals as intermediary reference signals embedded in the transmission. These pilot signals serve as mediators for phase estimation by providing known reference points that the receiver can correlate with the received signals. The correlation operation uses these pilot intermediaries to extract accurate phase information even in the presence of multipath interference and drift.
2Device complexity
If conventional AFC using only in-phase pilots is used, then device complexity is reduced, but demodulation accuracy deteriorates under varying channel conditions
Solution Approach 1:
The patent implements a dynamic AFC system that adapts to varying channel conditions. The system dynamically selects between using only in-phase pilots or using both in-phase and out-of-phase pilots based on the detected channel status. This dynamic adaptation allows the system to maintain low complexity when conditions permit while achieving high accuracy when channel variations require it.
Solution Approach 2:
The patent changes the parameter set used for phase correction based on channel conditions. When channels are stable, only in-phase pilot parameters are used. When channel variations occur, the system switches to using both in-phase and out-of-phase pilot parameters. This parameter change strategy allows flexible adaptation to different transmission environments without permanently increasing system complexity.
Data Source
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AI summary
Disclosed herein is a reception apparatus including: an acquisition section configured to acquire an orthogonal frequency division multiplexing signal composed resultingly of signals transmitted by the orthogonal frequency division multiplexing method from a plurality of transmission apparatuses; a correction value calculation block configured to calculate a correction value for correcting a drift amount of the orthogonal frequency division multiplexing signal using the phase of either a first pilot signal or a second pilot signal extracted from the acquired orthogonal frequency division multiplexing signal, the first pilot signal being obtained from pilot signals which are in phase with one another coming from the plurality of transmission apparatuses, the second pilot signal being acquired from pilot signals which are out of phase with one another coming from the plurality of transmission apparatuses; and a correction block configured to correct the drift amount of the orthogonal frequency division multiplexing signal in accordance with the calculated correction value.