Joint Reference Signal Structure for Wireless Frequency Synchronization
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Solution Overview
Problem
Next-generation wireless communication systems face complexity and increased overhead in synchronization procedures due to the elimination of always-available reference signals, leading to potential reductions in data rates and increased complexity in synchronization processes.
Innovation Solution
A joint reference signal structure is implemented, dividing the demodulation reference signal (DMRS) and synchronization signal (SS) to achieve efficient frequency synchronization without relying heavily on DMRS symbols, with SS having high density in the time domain and low density in the frequency domain, and vice versa for DMRS, thereby reducing overhead and enhancing demodulation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If always-available reference signals (CRS) are eliminated to reduce overhead and increase data rates, then spectral efficiency is improved, but frequency synchronization performance deteriorates
Solution Approach 1:
The patent segments the reference signal functionality by separating synchronization signals (SS) from demodulation reference signals (DMRS). SS are transmitted in dedicated resources for frequency synchronization, while DMRS are transmitted sparsely for channel estimation. This segmentation allows each signal type to be optimized independently, reducing overall overhead while maintaining synchronization accuracy.
Solution Approach 2:
The synchronization signal (SS) serves multiple functions: it provides both frequency synchronization and acts as a reference for channel estimation in the absence of always-available CRS. This multi-functionality reduces the need for separate reference signals, thereby reducing overhead while maintaining synchronization performance.
2Measurement precision
If demodulation reference signal (DMRS) density is increased to improve demodulation performance, then channel estimation accuracy is improved, but signal overhead increases
Solution Approach 1:
The patent segments channel estimation functionality between synchronization signals (SS) and demodulation reference signals (DMRS). SS provide coarse channel information and frequency synchronization, while DMRS provide fine-tuned channel estimation. This segmentation allows DMRS to be transmitted sparsely (reducing overhead) while still achieving accurate channel estimation through the combined use of SS and DMRS.
3Measurement precision
If synchronization signal (SS) density in time domain is increased to improve frequency synchronization, then synchronization accuracy is improved, but resource overhead increases
Solution Approach 1:
The patent applies local quality by concentrating SS resources in the time domain (multiple SS symbols within a subframe) rather than distributing them uniformly in both time and frequency. This localized concentration in time provides robust frequency synchronization without requiring high frequency-domain density, thereby reducing overall overhead while maintaining synchronization accuracy.
Data Source
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AI summary
Techniques are disclosed for transmitting and receiving a user-specific transmission comprising user data symbols and user-specific reference signal symbols. According to one aspect, a method comprises transmitting, within a group of time-frequency resources scheduled in a first time interval for a first user, a plurality of demodulation reference signal (DMRS) symbols, where the plurality of DMRS symbols within the group of time-frequency resources are more densely arranged in the frequency domain than in the time domain; and transmitting, within the group of time-frequency resources scheduled in the first time interval for the first user, a plurality of synchronization signal (SS) symbols, where the plurality of SS symbols within the group of time-frequency resources are more densely arranged in the time domain than in the frequency domain.