Complementary Sequence Encoding for Low PAPR OFDM Signals
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Solution Overview
Problem
Existing wireless communication systems face challenges in controlling peak-to-average power ratio (PAPR) in unlicensed bands, particularly for PUCCH signals, which can lead to increased complexity and power consumption at the receiver.
Innovation Solution
The use of complementary sequence (CS) encoding techniques, specifically Golay complementary sequences, to limit PAPR in OFDM symbols for both contiguous and non-contiguous frequency domain resource allocations, while minimizing receiver complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional encoding methods are used for PUCCH signals in unlicensed bands, then the system can operate in existing frameworks, but the peak-to-average power ratio (PAPR) increases leading to higher complexity and power consumption at the receiver
Solution Approach 1:
The patent applies parameter changes by transforming the encoding approach from conventional methods to complementary sequence (CS) encoding. Specifically, it uses Golay complementary sequences with specific mathematical properties (where the sum of autocorrelations of two sequences equals zero for all non-zero time shifts) to fundamentally alter the signal characteristics. This parameter transformation achieves PAPR reduction while maintaining signal integrity, directly resolving the contradiction between reliability and receiver complexity.
Solution Approach 2:
The patent employs composite materials principle by combining multiple complementary sequences to form a composite signal structure. It constructs encoded CS sequences by concatenating and modulating multiple base CS sequences, creating a composite signal that inherits the low-PAPR properties of individual sequences while achieving higher data rates. This composite structure enables simultaneous achievement of low PAPR and high spectral efficiency.
2Adaptability or versatility
If distinct channel encoding, modulation, and resource allocation procedures are implemented, then comprehensive communication functionality is achieved, but system complexity increases
Solution Approach 1:
The patent merges multiple distinct communication procedures into a unified complementary sequence encoding framework. It integrates channel encoding, modulation, and resource allocation into a single CS encoding process where information bits are directly mapped to CS sequences. This merging eliminates the need for separate processing stages, reducing system complexity while maintaining comprehensive communication functionality through the mathematical properties of CS sequences.
Solution Approach 2:
The patent achieves universality by designing a multi-functional complementary sequence encoding system that simultaneously performs encoding, modulation, and resource allocation. The CS sequences serve multiple purposes: they encode information, provide modulation through phase/amplitude variations, and enable flexible resource allocation through sequence selection. This multi-functionality reduces the number of separate components needed in the communication system.
3Reliability
If Golay complementary sequences are used for encoding, then PAPR is limited to less than 3 dB, but the encoding process requires specialized sequence generation
Solution Approach 1:
The patent applies segmentation by breaking down the complex Golay complementary sequence generation into manageable components. It divides the encoding process into stages: generating base CS sequences, selecting appropriate sequences based on data requirements, and concatenating them with specific modulation patterns. This segmentation makes the implementation more straightforward while maintaining the low-PAPR properties of the complete encoded sequence.
Data Source
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AI summary
Methods, apparatuses and systems directed to complementary sequence (CS) encoding and encoded CS transmissions are provided. Among the apparatuses is apparatus having a transmitter that may be configured to (i) transmit an encoded CS via a block based, e.g., orthogonal frequency division multiplexing (OFDM), waveform, and/or (ii) generate the encoded CS using a plurality of seed sequences and a plurality of information items, wherein: of the elements of the encoded CS encodes a first set of the plurality of information items; (b) phases of the encoded-CS elements encode a second set of the plurality of information items); and (c) the encoded-CS elements define a number of zeros that encode a third set of the plurality of information items. The encoded-CS elements may define respective numbers of zeros that collectively form the number of zeros that encode the third information-item set.