Cell Search Synchronization Using Side Information
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Solution Overview
Problem
Cell search in wireless communication systems, particularly in LTE-Advanced carrier aggregation, faces challenges with low Signal-to-Interference-plus-Noise-Ratio (SINR) and high computational complexity, especially in heterogeneous network deployments where synchronization is difficult due to interference from macro cells to pico or femto cells.
Innovation Solution
The method involves utilizing side information such as cell ID and carrier frequency to reduce the number of hypotheses in cell search, adapt the receiver window, and perform detection using a subset of synchronization signals, thereby minimizing complexity and power consumption while achieving synchronization at low SINRs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cell search is performed using traditional methods with full hypothesis testing, then detection accuracy is improved, but computational complexity and power consumption increase significantly
Solution Approach 1:
The patent applies preliminary action by utilizing side information (cell ID, carrier frequency) obtained during SCell configuration to pre-determine which synchronization signals to search for and where to search. This eliminates the need to test all possible hypotheses, as the search space is narrowed in advance based on previously received configuration information from the eNodeB.
Solution Approach 2:
The patent segments the cell search process into targeted steps based on side information. Instead of a unified exhaustive search, the method divides the synchronization signal detection into specific segments: determining search space based on cell ID, selecting specific synchronization signals to search, and focusing correlation operations only on relevant time-frequency resources.
2Reliability
If cell search accumulates correlation values over many radio frames to handle low SINR, then detection reliability is improved, but time consumption and complexity increase
Solution Approach 1:
The patent uses side information received during SCell configuration to perform preliminary determination of the search space and target synchronization signals. This preliminary action enables the UE to start accumulated correlation immediately with focused hypotheses, rather than needing to accumulate over many frames testing all possibilities, thus achieving reliable detection faster.
3Area of stationary object
If the UE searches for synchronization signals on all possible cells, then coverage is improved, but power consumption increases
Solution Approach 1:
The patent extracts and utilizes side information (cell ID, carrier frequency) from the SCell configuration to eliminate unnecessary search hypotheses. By taking out the irrelevant search spaces and focusing only on the specific cell indicated by side information, the UE reduces power consumption while maintaining coverage capability for the intended cell.
4Reliability
If traditional cell search methods are used in heterogeneous networks with macro and pico cells, then interference coordination is improved, but synchronization performance deteriorates due to lack of coordination on synchronization channels
Solution Approach 1:
The patent applies preliminary action by having the eNodeB provide side information about the target SCell before the UE attempts synchronization. This preliminary information includes cell ID and carrier frequency, which enables the UE to directly search for the correct synchronization signals without being confused by interference from other cells in the heterogeneous network, thus improving synchronization performance despite lack of interference coordination on sync channels.
Data Source
AI summary
A receiver performs synchronization to a secondary component carrier in a wireless communication system. The secondary component carrier is aggregated with a primary component carrier in the wireless communication system. Side information of the secondary component carrier is utilized to reduce occurrences of a number of synchronization hypotheses in a hypothesis test in the case that synchronization to the secondary component carrier is performed. Symbol timing synchronization of the secondary component carrier is determined in accordance with the reduced occurrences of the number of synchronization hypotheses.