Zadoff-Chu Sequence Length Selection for Low PAPR Reference Signals
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Solution Overview
Problem
In LTE systems, the limited transmit power of cell-edge users results in reduced accuracy of channel-related information measurement, deteriorating data transmission performance due to high peak-to-average ratio (PAPR) and raw cubic metric (RCM) of reference signals, especially when using block reference signals or frequency domain filters.
Innovation Solution
Generating reference signal sequences based on ZC sequences with specific length values and applying linear phase rotation to achieve low PAPR/RCM, ensuring orthogonality and improving data transmission performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional reference signal sequences are used in LTE systems, then orthogonality between reference signals is maintained, but PAPR and RCM remain high, reducing measurement accuracy for cell-edge users
Solution Approach 1:
The patent applies parameter changes by modifying the reference signal sequence generation parameters. Specifically, it uses ZC sequences with optimized root indices and lengths, and introduces linear phase rotation parameters to transform the reference signal sequences. These parameter modifications reduce PAPR and RCM while maintaining sequence orthogonality, directly resolving the contradiction between measurement accuracy and harmful factors.
Solution Approach 2:
The patent substitutes the conventional reference signal generation mechanism with a new approach based on ZC sequences and linear phase rotation. Instead of using traditional sequence generation methods that result in high PAPR/RCM, the invention replaces them with mathematically optimized sequences that inherently have lower peak values, thereby reducing the harmful effects on cell-edge users.
2Power
If transmit power is limited for cell-edge users, then power constraints are satisfied, but channel measurement accuracy deteriorates due to high PAPR/RCM
Solution Approach 1:
The patent converts the harmful effect of high PAPR/RCM into a benefit by using the same ZC sequence structure but with optimized parameters and linear phase rotation. This transformation maintains the useful properties of ZC sequences (orthogonality, good autocorrelation) while eliminating the harmful peak power characteristics, enabling cell-edge users to achieve accurate measurements within power constraints.
3Productivity
If block reference signals or frequency domain filters are used, then resource efficiency is improved, but PAPR and RCM increase, further reducing measurement accuracy
Solution Approach 1:
The patent introduces dynamic linear phase rotation parameters that can be adjusted based on channel conditions and resource allocation. This dynamic approach allows the system to maintain low PAPR/RCM characteristics while adapting to different resource efficiency requirements, resolving the contradiction between resource efficiency and harmful factors.
Data Source
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AI summary
This application provides a reference signal transmission method and a device. The method includes: converting, by a sending device, a frequency domain reference signal from frequency domain to time domain, to generate a time domain reference signal, where the frequency domain reference signal includes a reference signal sequence mapped to a frequency domain resource, the reference signal sequence is determined based on a Zadoff-Chu sequence, and a length value of the Zadoff-Chu sequence is selected from at least two length values; and sending, by the sending device, the time domain reference signal. According to the reference signal transmission method in this application, one ZC sequence is selected from at least two ZC sequences with different lengths to generate the reference signal sequence, so that the generated reference signal sequence is characterized by a PAPR and an RCM. The reference signal sequence is used to generate a reference signal, to improve data transmission performance.