Base Station Synchronization Signal Generation for Carrier Aggregation
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Solution Overview
Problem
In existing communication systems, the efficiency of cell search and synchronization signal arrangement is low due to the need to perform multiple cell searches for each component carrier and the requirement of multiple downlink synchronization signals for different Physical Cell Identities (PCIs), which hampers efficient carrier aggregation.
Innovation Solution
A base station device and mobile station device configuration that generates and transmits synchronization signals using distinct parameters for different frequency bands, allowing for efficient aggregation by using a virtual cell identity in one frequency band and a physical cell identity in another, thereby reducing the number of cell searches and synchronization signal overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple downlink synchronization signals are arranged for different PCIs in carrier aggregation, then cell identification accuracy is improved, but the number of cell searches and synchronization signal overhead increases
Solution Approach 1:
The patent uses a virtual cell identity (V-PCI) that is copied or derived from the physical cell identity (PCI) of the primary cell. The V-PCI allows the mobile station to identify the secondary cell without requiring a separate synchronization signal, thereby reducing the number of cell searches while maintaining identification accuracy through the relationship between PCI and V-PCI.
Solution Approach 2:
The synchronization signal of the primary cell serves multiple functions: it enables cell identification for the primary cell itself and also provides the basis for identifying secondary cells through the V-PCI relationship. This multi-functionality eliminates the need for separate synchronization signals for each component carrier.
2Measurement precision
If multiple downlink synchronization signals are arranged for different PCIs in carrier aggregation, then cell identification accuracy is improved, but synchronization signal overhead increases
Solution Approach 1:
Instead of transmitting separate synchronization signals for each component carrier, the system copies the PCI information to create a V-PCI for secondary cells. This copying approach maintains identification capability while eliminating redundant synchronization signal transmissions, thereby reducing overhead.
Solution Approach 2:
The patent extracts the essential cell identification function from the synchronization signal and separates it from the actual signal transmission. The PCI/V-PCI relationship allows cell identification to be achieved through information extraction and calculation rather than through repeated signal transmission.
3Loss of time
If a single PCI is used for all component carriers in carrier aggregation, then the number of cell searches is reduced, but inter-cell interference increases
Solution Approach 1:
The patent applies different identity characteristics to different component carriers: the primary cell uses the actual PCI while secondary cells use derived V-PCIs. This local differentiation allows each cell to have unique identification properties, reducing inter-cell interference, while the overall aggregation process remains efficient.
Solution Approach 2:
The cell identity space is segmented into primary PCI and virtual PCI domains. The primary PCI identifies the primary cell, while V-PCIs identify secondary cells. This segmentation allows distinct identification for each component carrier, reducing interference while maintaining efficient aggregation through the structured relationship between PCI and V-PCI.
Data Source
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AI summary
A communication system which performs communication between a base station device configuring at least one cell and a mobile station device, wherein: the base station device includes: a synchronization signal generation unit which generates a synchronization signal corresponding to a cell identity for identifying a cell; and a transmission unit which generates a first transmission signal including the synchronization signal using a first parameter obtained from the cell identity, generates a second transmission signal excluding the synchronization signal using a second parameter obtained from a virtual cell identity different from the cell identity, transmits the first transmission signal using a first frequency band, and transmits the second transmission signal via a second frequency band different from the first frequency band. The mobile station device includes: a reception unit which receives a first reception signal including the synchronization signal using the first parameter obtained from the cell identity via the first frequency band and receives a second reception signal using the second parameter obtained from the virtual cell identity via the second frequency band.