Wireless Communication Apparatus Reducing PAPR via Selective Reference Symbols
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Solution Overview
Problem
In OFDM systems, the high peak-to-average power ratio (PAPR) leads to signal distortion, and existing methods like PTS reduce PAPR but at the cost of data rate due to the need for reference symbols, which can be inefficient, especially with a large number of subcarriers.
Innovation Solution
A wireless communication apparatus that divides subcarriers into segments, inserts reference symbols with predetermined phases, performs phase rotations based on various combination patterns, and selects the transmission signal with the smallest PAPR, allowing for accurate phase rotation detection and cancellation, thereby reducing PAPR without significantly reducing data rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reference symbols are inserted into each segment to notify phase rotations, then phase rotation detection accuracy is improved, but data rate decreases
Solution Approach 1:
The patent divides subcarriers into multiple segments and inserts reference symbols selectively in only some segments rather than all segments. This segmentation approach allows the system to maintain phase rotation detection capability while reducing the total number of reference symbols, thereby preserving more subcarriers for data transmission and improving overall data rate.
Solution Approach 2:
The patent makes the reference symbol insertion pattern configurable and adaptable to different system conditions. The same reference symbol mechanism serves multiple purposes: it provides phase rotation notification in segments where it is inserted, and its configurable presence/absence pattern allows optimization between detection accuracy and data rate based on specific system requirements.
2Reliability
If the amount of information in reference symbols is increased to achieve robustness in phase rotation notification, then reliability is improved, but data rate reduction increases
Solution Approach 1:
Instead of increasing information density in each reference symbol, the patent distributes phase rotation information across multiple segments selectively. By inserting reference symbols in only some segments, the system maintains robustness through spatial distribution rather than increasing information content per symbol, thus avoiding additional data rate penalties.
Solution Approach 2:
The patent changes the parameter of reference symbol insertion from 'all segments' to 'selective segments'. This parameter change allows the system to achieve robust phase rotation notification by strategically placing reference symbols in segments where they provide maximum benefit, while minimizing their total number to preserve data rate.
Data Source
AI summary
In some embodiments, a wireless communication apparatus may include, but is not limited to, a segment divider, a reference symbol inserter, a phase rotator, an adder, and a peak-to-average power ratio evaluator. The reference symbol inserter inserts at least one reference symbol having a phase into at least one of the subcarrier segments. The phase rotator performs respective phase rotations to the subcarrier segments, based at least in part on a plurality of different combination patterns, each of the different combination patterns identifying a respective phase rotation to the subcarrier segments. The peak-to-average power ratio evaluator calculates, for each of the plurality of different combination patterns, a peak-to-average power ratio of the transmission signals generated. The peak-to-average power ratio evaluator selects, from the transmission signals, a transmission signal having a smallest peak-to-average power ratio among the plurality of peak-to-average power ratios calculated.