Nested Orthogonal Phase Pattern Vectors for mmWave Synchronization
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Solution Overview
Problem
In ultrahigh frequency wireless communication systems, the Doppler effect and carrier frequency offset (CFO) caused by oscillator differences between user equipment (UE) and base stations (BS) lead to synchronization challenges, particularly in mmWave systems where Doppler spread and CFO are more significant due to higher frequencies, necessitating a more effective synchronization signal transmission method.
Innovation Solution
A method involving a nested orthogonal phase pattern vector set is used for synchronization signals, where base stations transmit synchronization signals with hierarchical phase pattern vectors, allowing for efficient sequence reuse and correlation-based connection establishment between UE and BS, reducing implementation complexity and memory demand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional reference symbol-based CFO estimation is used in ultrahigh frequency systems, then the method is simple to implement, but the CFO estimation accuracy deteriorates due to increased Doppler effect and carrier frequency offset at higher frequencies
Solution Approach 1:
The synchronization signal is segmented into multiple sequences with different phase patterns. Each sequence corresponds to a specific phase pattern vector, allowing the receiver to estimate CFO by comparing received signals with multiple known phase patterns. This segmentation enables more accurate CFO estimation without requiring a single complex reference symbol structure.
Solution Approach 2:
The invention changes the phase parameters of synchronization sequences by applying different phase pattern vectors. By varying the phase parameters across multiple sequences while maintaining orthogonal properties, the system enables accurate CFO estimation through phase correlation without increasing overall signal complexity.
2Loss of time
If multiple base stations transmit synchronization signals simultaneously, then connection establishment speed improves, but interference between base stations increases
Solution Approach 1:
Each base station is assigned a unique local phase pattern vector that distinguishes its synchronization signal from others. This local quality differentiation allows simultaneous transmission from multiple base stations without interference, as each signal maintains its unique phase characteristics for identification and correlation.
Solution Approach 2:
The invention introduces asymmetric phase pattern vectors for different base stations, where each base station uses a distinct phase progression pattern. This asymmetry ensures that synchronization signals from multiple base stations remain distinguishable and non-interfering, enabling parallel connection establishment.
3Productivity
If phase pattern vectors are reused across different hierarchies, then sequence efficiency improves, but orthogonality between signals deteriorates
Solution Approach 1:
The invention implements a nested hierarchy where phase pattern vectors are organized in hierarchical levels. Lower hierarchy base stations use phase patterns that are nested within or orthogonal to higher hierarchy patterns, allowing sequence reuse across hierarchies while maintaining orthogonality through the nested structure.
Solution Approach 2:
The invention extends the phase pattern space by introducing hierarchical dimensions. Phase patterns are differentiated not only by their basic orthogonal properties but also by their hierarchical level, creating an additional dimension for signal differentiation that enables reuse while preserving orthogonality.
Data Source
AI summary
Disclosed is a method for receiving a synchronization signal, comprising: respectively receiving, from a plurality of base stations, a plurality of synchronization signals generated by using a phase pattern vector set, which is nested orthogonal and hierarchically configured; measuring a sequence index and an index of a phase pattern vector for the plurality of synchronization signals; selecting, among the plurality of base stations, a base station having the highest correlation value calculated as a measurement result; and establishing a connection with the selected base station, wherein the phase pattern vector set has different phase pattern vectors for changing a phase of a synchronization signal sequence up to a predetermined repetition number.