Wireless Reference Signals with QA Sequences for Low-Interference Estimation
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Solution Overview
Problem
Existing wireless communication systems face challenges with channel aging and intra-/inter-cell cross reference signal interference, particularly in TDD systems, leading to inefficient DL precoding and increased interference, which degrades throughput and channel estimation accuracy.
Innovation Solution
Implement a set of QA modulation sequences with specific correlation criteria to generate a larger number of reference signals, ensuring orthogonal transmission and low interference, using cyclically shifted versions and compressive sensing for accurate channel estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of reference signals is increased to support more devices per cell, then system throughput is improved, but reference signal interference between cells increases
Solution Approach 1:
The patent segments the set of modulation sequences into Q subsets, where each subset contains A modulation sequences. Reference signals from different subsets are assigned to different cells, creating a hierarchical structure that enables both increased reference signal capacity and interference management through subset-based resource allocation
Solution Approach 2:
The patent changes the parameter of modulation sequence selection by introducing subset indexing (q=0 to Q-1) and intra-subset indexing (n=0 to A-1). This parameterization allows systematic control of reference signal generation, enabling more reference signals to be generated while maintaining orthogonality properties through controlled parameter combinations
2Measurement precision
If reference signal transmission period is shortened to reduce channel aging, then channel estimation accuracy is improved, but system overhead increases
Solution Approach 1:
The patent generates multiple reference signals by copying and cyclically shifting base modulation sequences within subsets. This allows the system to create diverse reference signals without requiring additional transmission resources, effectively reducing the need for frequent reference signal transmissions while maintaining accurate channel estimation
3Quantity of substance
If more modulation sequences are used to generate reference signals, then the number of supported devices is increased, but sequence design complexity increases
Solution Approach 1:
The patent divides the modulation sequence design into segmented subsets, where each subset contains A sequences with controlled correlation properties. This segmentation reduces the overall design complexity by breaking down the problem of generating QA sequences into manageable subset-based design units with predictable orthogonality characteristics
Solution Approach 2:
The patent uses parameter-based generation of modulation sequences through cyclic shifts and phase rotations controlled by parameters q and n. This parametric approach simplifies sequence design by allowing systematic generation of diverse sequences from base patterns, reducing design complexity while increasing the number of available reference signals
Data Source
AI summary
First and second communication devices employ reference signals for channel estimation in a communication system. The reference signals are based on modulation sequences from a set of QA modulation sequences of length L≥1. The set of QA modulation sequences includes Q subsets of modulation sequences, Q≥1, where each subset of modulation sequences comprises A modulation sequences, A≥1. A correlation between any two reference signals based on any two modulation sequences in a same subset of modulation sequences satisfies a first correlation criterion, and a correlation between any two reference signals based on any two modulation sequences in respective any two different subsets of modulation sequences satisfies a second correlation criterion.