OFDM Phase Rotation Estimation via Pilot Segmentation
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Solution Overview
Problem
In OFDM systems, the high peak-to-average power ratio (PAPR) of signals leads to distortion in power amplifiers, and existing methods like PTS struggle to accurately estimate phase rotations in wireless transmission paths, causing interference and reducing system efficiency.
Innovation Solution
A wireless communication apparatus that includes a pilot inserter, segment divider, and phase rotator to insert pilot symbols, divide subcarriers into segments, and perform phase rotations, allowing for accurate estimation and cancellation of phase rotations in both the transmitter and receiver, thereby reducing PAPR and improving signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If PTS phase rotation is applied to reduce PAPR, then signal distortion is reduced, but accurate estimation of phase rotation becomes difficult due to interference between PTS phase rotation and transmission path phase rotation
Solution Approach 1:
The patent introduces a reference symbol as an intermediary element that is not subjected to PTS phase rotation. This reference symbol serves as a clean reference point that allows the receiver to separately estimate the transmission path phase rotation without interference from PTS phase rotation, thereby resolving the estimation accuracy problem while maintaining PAPR reduction benefits
Solution Approach 2:
The patent segments the subcarriers into multiple groups and applies different processing: reference symbols are placed in specific subcarrier positions that remain unrotated by PTS, while data subcarriers receive PTS phase rotation. This segmentation allows simultaneous achievement of PAPR reduction and accurate phase estimation
2Loss of information
If reference symbols are transmitted to estimate phase rotation, then phase rotation information can be acquired, but the phase rotation amount includes both PTS phase rotation and transmission path phase rotation making separate estimation difficult
Solution Approach 1:
The reference symbol acts as an intermediary that carries only transmission path phase rotation information without PTS phase rotation interference. By comparing the transmitted reference symbol with the received reference symbol, the receiver can accurately estimate only the transmission path phase rotation, separating it from PTS phase rotation effects
Solution Approach 2:
The patent extracts the transmission path phase rotation information from the overall phase rotation by using reference symbols that are excluded from PTS processing. This extraction allows the receiver to obtain pure transmission path phase rotation data without contamination from PTS phase rotation
Data Source
AI summary
In some embodiments, a wireless communication apparatus may include, but is not limited to, a pilot inserter, a segment divider, a phase rotator, and a first adder. The pilot inserter inserts first and second pilot symbols into a symbol stream. The segment divider divides into a plurality of segments a plurality of subcarriers. Each of the subcarriers is allocated with a respective one of the symbols included in the symbol stream into which the first and second pilot symbols have been inserted. The phase rotator performs, for each segment, a phase rotation to all of the symbols, except for a predetermined one of the first and second pilot symbols, included in the symbol stream. The first adder adds together signals corresponding to the subcarriers included in the plurality of segments to which the phase rotation has been performed by the phase rotator to generate a transmission signal.