Independent Paging and Access Cell Selection in Mobile Networks
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Solution Overview
Problem
In mobile cellular networks with hierarchical structures, including macrocells and femtocells, frequent location updates are necessary as users move, leading to increased power consumption and bandwidth usage, particularly when moving between femtocells and macrocells with different location area identifiers, which reduces network efficiency and increases the need for battery recharging.
Innovation Solution
A method where a mobile device selects a paging cell based on paging capabilities, favoring macrocells for reduced location updates, and an access cell based on access capabilities, allowing for independent selection to optimize both paging and access processes, with higher paging capability values assigned to macrocells and access capability values to femtocells, ensuring efficient paging and access without sacrificing quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the network uses traditional paging procedures where the UE's location area is registered and paging messages are broadcast in cells with the applicable LAI, then the network can contact the UE when a call is directed to it, but frequent location updates are necessary as users move between femtocells and macrocells with different location area identifiers, leading to increased power consumption and bandwidth usage
Solution Approach 1:
The patent segments the cell selection process into two independent parts: access cell selection and paging cell selection. The access cell is selected based on access capabilities (signal strength, quality) while the paging cell is selected based on paging capabilities (location area coverage, macrocell preference). This segmentation allows the UE to camp on a femtocell for good access quality while registering in a macrocell's location area for efficient paging, reducing location updates and power consumption.
Solution Approach 2:
The patent applies local quality by allowing different cells to serve different functions with different selection criteria. The access cell prioritizes local signal quality for communication, while the paging cell prioritizes broader location area coverage for network contact. This enables the UE to optimize for access quality locally while maintaining efficient paging registration globally.
2Loss of information
If the UE frequently updates its location when moving between cells with different location area identifiers, then the network maintains accurate location information, but this increases bandwidth usage and reduces network efficiency
Solution Approach 1:
By separating access cell and paging cell selection, the patent reduces the frequency of location updates. The UE only needs to update its paging cell registration when moving between macrocells or when access quality degrades, rather than updating every time it moves between any cells with different LAIs. This segmentation significantly reduces location update frequency and associated bandwidth usage.
3Reliability
If the UE selects cells based solely on access capabilities, then communication quality is optimized, but paging efficiency deteriorates due to excessive location updates when moving between femtocells and macrocells
Solution Approach 1:
The patent divides cell selection into two independent selection processes: one for access cell based on access capabilities (signal strength, communication quality) and one for paging cell based on paging capabilities (location area coverage, macrocell preference). This allows simultaneous optimization of both communication quality and paging efficiency without compromise.
Solution Approach 2:
The patent enables different quality metrics to apply to different functional aspects: access cell selection optimizes for local communication quality, while paging cell selection optimizes for global paging efficiency. The UE can thus maintain high communication quality through femtocell access while achieving paging efficiency through macrocell registration.
4Productivity
If macrocells are used for paging, then location update frequency is reduced, but access quality may be compromised compared to femtocells
Solution Approach 1:
The patent segments the cell selection function so that macrocells can be used for paging registration (reducing location updates) while femtocells can be used for access (providing better access quality). The UE independently selects the best cell for each function, allowing macrocells to serve paging purposes and femtocells to serve access purposes simultaneously.
Solution Approach 2:
The patent enables cells to serve multiple functions: a femtocell can provide both access service and paging service, while a macrocell can provide paging service. The UE can camp on a femtocell for access while using its location area registration in a macrocell for paging, allowing the system to leverage the strengths of different cell types for different functions.
Data Source
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AI summary
In a mobile network a mobile device selects a paging cell whose location area is registered to the network and determines where paging of this mobile device takes place, and selects an access cell to be used by the mobile device when connecting to the network. When the mobile device receives a paging message in the paging cell it sends the paging response through the access cell. Nodes in the mobile network are configured not to reject or filter out paging responses received from mobile devices that this node did not page; instead the nodes initiate call setup for such mobile devices.