Cell Searcher Module Synchronization Channel Interference Cancellation
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Solution Overview
Problem
In synchronous wireless communication networks, the strong serving cell signal interferes with the detection of neighbor cells sharing the same primary synchronization channel sequence, leading to failure in identifying new neighbor cells due to incorrect channel estimation.
Innovation Solution
The cell searcher module generates a joint estimate of the received power of secondary synchronization channel sequences for both the serving and hypothetical neighbor cells, reconstructs and subtracts the serving cell's synchronization channel signals to mitigate interference, and correlates channel responses to identify neighbor cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the UE uses PSCH sequence to estimate the channel reference in a synchronous network, then the channel reference can be obtained for processing SSCH, but the serving cell signal strength dominates and causes the UE to estimate the propagation channel from the serving cell rather than the neighbor cell, leading to corrupted channel estimates and failure in identifying neighbor cells
Solution Approach 1:
The patent extracts and removes the serving cell signal component from the composite received signal. By separating the known serving cell PSCH and SSCH sequences from the received signal, the system isolates and eliminates the dominant serving cell interference, allowing clear detection of neighbor cell signals that would otherwise be masked by the stronger serving cell transmission.
Solution Approach 2:
The patent applies preliminary anti-action by pre-subtracting the reconstructed serving cell signal from the received signal before attempting to detect neighbor cell sequences. This proactive interference cancellation prevents the serving cell signal from corrupting the channel estimation process, enabling accurate neighbor cell identification even in synchronous networks where timing alignment causes signal overlap.
2Reliability
If the serving cell signal strength is strong in a synchronous deployment, then the serving cell transmission is reliably received, but the strong serving cell signal prevents the UE from detecting neighbor cells with the same PSCH sequence due to signal dominance and corrupted channel estimates
Solution Approach 1:
The patent extracts the serving cell signal component from the composite received signal by reconstructing it using known PSCH and SSCH sequences. This extraction removes the dominant serving cell transmission that masks neighbor cell signals, enabling the UE to detect and measure neighbor cells even when the serving cell signal is strong and reliable.
Solution Approach 2:
The patent uses the known serving cell synchronization sequences as an intermediary to facilitate neighbor cell detection. By using the serving cell's own sequences as a reference for reconstruction and subtraction, the system creates a mediator process that eliminates serving cell interference and enables clear detection of previously undetectable neighbor cell signals.
3Productivity
If PSCH and SSCH are transmitted in overlapping subframes from serving and neighbor cells in a synchronous network, then time and frequency resources are efficiently utilized, but the overlapping transmissions cause interference that prevents accurate identification of neighbor cells
Solution Approach 1:
The patent extracts and removes the serving cell's PSCH and SSCH components from the overlapping transmissions. By separating the known serving cell sequences from the composite signal, the system eliminates the interference caused by simultaneous transmissions, allowing recovery and identification of neighbor cell information that would otherwise be lost in the overlapping signal mixture.
Solution Approach 2:
The patent converts the harmful effect of overlapping transmissions into a beneficial process. By using the known serving cell sequences that cause interference to reconstruct and subtract the serving cell signal, the system transforms the interfering serving cell transmission into a useful reference that enables cancellation and reveals the hidden neighbor cell information embedded in the overlapping signal.
Data Source
AI summary
The cell searcher module (CSM) of a wireless communication device detects that the device is in coverage region of an eNB by processing received signal associated with the primary synchronization (PSCH) and secondary synchronization (SSCH) sequences transmitted by the eNB. The wireless device determines whether candidate SCH signals from candidate neighbor cells are synchronous with SCH sequences from the serving cell by implementing one of three methods. In a first method, the CSM generates a joint estimate of the received power of SSCH sequences corresponding to already detected/identified serving cell and a hypothetical neighbor cell. In a second method, the CSM re-constructs SCH sequences corresponding to already detected cells and subtracts the re-constructed SCH sequences from the received signal to obtain a residual signal with reduced serving cell interference. In a third embodiment, the CSM performs a correlation of estimated channel responses to determine whether the neighbor cell is present.