Reduced Complexity Primary Synchronization Sequence Design for OFDMA
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Solution Overview
Problem
In cellular communication systems using OFDMA, the initial cell search process involves high computational complexity for user equipment to identify primary synchronization signals from adjacent base stations, leading to inefficiencies in timing and frequency acquisition.
Innovation Solution
Implementing a base station transmitter and user equipment receiver with a scheduling unit and processing unit that utilize distinguishable primary synchronization sequences with reduced computational complexity, designed in both frequency-domain and time-domain structures, allowing for efficient identification and correlation of primary synchronization signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional primary synchronization sequences are used in OFDMA systems, then reliable cell search and synchronization can be achieved, but the computational complexity for user equipment to identify synchronization signals from adjacent base stations becomes high
Solution Approach 1:
The patent divides the synchronization signal identification process into two stages: first identifying the group of synchronized base stations using a first set of sequences, then identifying the specific base station within that group using a second set of sequences. This segmentation reduces computational complexity by breaking down the search process into manageable portions, where the first stage narrows down candidates and the second stage performs precise identification only among reduced candidates.
Solution Approach 2:
The patent employs different primary synchronization sequences for different groups of base stations, where each group is characterized by specific properties (such as root indices in Zadoff-Chu sequences). By assigning distinct local characteristics to different base station groups, the system enables efficient differentiation between adjacent cells without requiring exhaustive search across all possible sequences, thus reducing overall computational complexity while maintaining identification reliability.
2Measurement precision
If multiple distinguishable primary synchronization sequences are transmitted by adjacent base stations, then accurate cell identification is enabled, but the complexity of processing and correlating multiple sequences increases
Solution Approach 1:
The patent performs preliminary actions by pre-configuring and pre-distributing specific primary synchronization sequences to different base station groups before the actual cell search process. The user equipment is also pre-provided with these sequences in advance. This preliminary preparation eliminates the need for real-time generation or complex analysis of synchronization sequences during the cell search, significantly reducing processing complexity while enabling accurate cell identification.
Solution Approach 2:
The patent uses copies of standardized primary synchronization sequences (such as Zadoff-Chu sequences with different root indices) for different base station groups. Instead of requiring the user equipment to process completely different signal structures, the system uses variations of a known sequence template, which simplifies the correlation process while still enabling distinguishable identification of different cells through the copied sequence variations.
3Adaptability or versatility
If conventional synchronization signal structures are used, then compatibility with existing OFDMA systems is maintained, but the initial cell search process becomes time-consuming
Solution Approach 1:
The patent introduces dynamic grouping of base stations into different sets based on their synchronization characteristics. Instead of treating all base stations uniformly, the system dynamically organizes them into groups that share common synchronization properties. This dynamic organization enables the user equipment to adapt its search strategy by first targeting specific groups with known sequences, thereby reducing cell search time while maintaining compatibility with the broader OFDMA system architecture.
Data Source
AI summary
The present disclosure provides a base station transmitter, a user equipment receiver and methods of operating a base station transmitter and a user equipment receiver. In one embodiment, the base station transmitter is for use with a cellular communication system and includes a scheduling unit configured to provide a primary synchronization sequence that is distinguishable from other primary synchronization sequences employed by adjacent base station transmitters located in contiguous communication cells, wherein a primary synchronization sequence structure is based on a reduced computational complexity for identification of the primary synchronization sequence in a user equipment receiver. Additionally, the base station transmitter also includes a transmit unit configured to transmit a primary synchronization signal corresponding to the primary synchronization sequence.