Low-Complexity Primary Synchronization Sequences for OFDMA Cell Search
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing cellular communication systems face challenges in efficiently performing initial cell search due to high computational complexity and sensitivity to frequency offsets, particularly in orthogonal frequency division multiple access (OFDMA) systems, which affect the synchronization process between base stations and user equipment.
Innovation Solution
Employing distinct primary synchronization sequences with complex conjugate symmetry in the time domain, such as Zadoff-Chu sequences, to reduce computational complexity and mitigate frequency offset sensitivity, using techniques like complex conjugate correlation and phase correlation to optimize synchronization signal design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional synchronization sequences are used in OFDMA systems, then initial cell search can be performed, but computational complexity is high and frequency offset sensitivity is high
Solution Approach 1:
The patent changes the fundamental parameter of the synchronization sequence from conventional designs to Zadoff-Chu sequences with specific root indices. This parameter change provides constant amplitude zero autocorrelation properties, which reduces computational complexity for correlation operations while improving frequency offset tolerance and synchronization accuracy in OFDMA systems
Solution Approach 2:
The patent employs asymmetric Zadoff-Chu sequences where the root index selection creates specific asymmetric properties that provide directional frequency offset tolerance. The sequences are designed with specific root indices (e.g., u=1, 2, 3 for different cell groups) that create asymmetric correlation patterns, enabling the receiver to distinguish and correct frequency offsets more effectively while reducing computational burden
2Reliability
If conventional synchronization sequences are used, then cell search can be initiated, but frequency offset sensitivity is high
Solution Approach 1:
The patent changes the sequence parameter to Zadoff-Chu sequences with specific root indices selected from defined sets. These parameter changes provide inherent frequency offset tolerance through their autocorrelation properties, where the constant amplitude zero autocorrelation characteristic maintains synchronization accuracy even in the presence of frequency offsets
Solution Approach 2:
The patent converts the harmful effect of frequency offsets into a beneficial feature by designing Zadoff-Chu sequences where frequency shifts produce predictable phase rotations rather than destructive interference. The specific root index selection ensures that frequency offsets transform the signal in a controllable manner that can be easily compensated, turning frequency sensitivity into frequency tolerance
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Embodiments of the present disclosure provide a transmitter, a receiver and methods of operating a transmitter and a receiver. In one embodiment, a user equipment (110) comprises a receiver (111) configured to receive a primary synchronization signal, and a unit (112) configured to identify one of a plurality of primary communication signals corresponding to a communication cell location of the receiver, wherein at least two of a group of multiple sequences have complex conjugate symmetry in the time domain. In another embodiment a corresponding method of operating a receiver in a user equipment (110) is provided.