LAA Cell Discovery Signal Detection in Unlicensed Bands
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In densely deployed small cell environments, user equipment (UE) faces difficulties in quickly detecting small cells due to intermittent transmission of discovery signals in unlicensed bands, especially when neighboring IEEE 802.11 systems are active, leading to incomplete cell identification and inefficient frequency utilization.
Innovation Solution
A method and apparatus for UE to receive a discovery signal measurement timing configuration (DMTC) for License Assisted Access (LAA) cells, allowing for periodic cell detection and measurement within specific subframes, including primary synchronization signals (PSS), secondary synchronization signals (SSS), and cell-specific reference signals (CRS), to enhance cell identification efficiency in unlicensed bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If small cells transmit discovery signals periodically in unlicensed bands, then frequency utilization is improved, but cell detection speed deteriorates when neighboring IEEE 802.11 systems are active
Solution Approach 1:
The patent applies preliminary action by having the UE perform cell detection before measurement. The UE first detects the presence of the discovery signal in the first subframe, and only if detection is successful does it proceed to perform measurements in the second subframe. This preliminary detection step ensures that the UE can quickly identify small cells even when discovery signals are intermittently transmitted due to CCA failures in unlicensed bands.
2Object-affected harmful factors
If discovery signals are transmitted intermittently due to CCA failures, then neighboring channel interference is reduced, but cell identification completeness deteriorates
Solution Approach 1:
The patent ensures cell identification completeness by performing detection in the first subframe before measurements in the second subframe. This preliminary detection action allows the UE to identify small cells reliably even when discovery signals are transmitted intermittently due to CCA failures, maintaining complete cell identification while reducing neighboring channel interference.
3Loss of time
If UE performs both cell detection and measurement in the same subframe, then time efficiency is improved, but signal processing accuracy deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the discovery signal occasion into two distinct subframes: the first subframe dedicated to cell detection and the second subframe dedicated to measurements. This temporal segmentation allows the UE to perform detection and measurement functions separately, ensuring signal processing accuracy while maintaining time efficiency through the structured division of tasks.
Data Source
AI summary
One disclosure of the present specification provides a method for receiving a discovery signal from a license assisted access (LAA) based cell operating in an unlicensed band. The method may be performed by a user equipment (UE) and comprise: receiving a discovery signal measurement timing configuration (DMTC) including information on a periodicity of the DMTC and information on an occasion duration of a discovery signal. Here, if the UE operate in a bandwidth of 10 Mhz, the occasion duration may include a first subframe and a second subframe. The method may comprise: performing a cell detection for the LAA based cell operating in the unlicensed band, on the first subframe of the occasion duration; and performing measurements for the LAA based cell operating in the unlicensed band, on the second subframe of the occasion duration.