Cell Reselection for Switched-Off Home eNodeB
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Solution Overview
Problem
Existing cell reselection and handover procedures in wireless communication systems fail when user equipment (UE) moves from a macrocell to a Home eNodeB (HeNB) whose radio section is switched off, leading to disconnection and delayed handover due to the inability to measure the HeNB's RSRP until it is switched on.
Innovation Solution
The method involves the UE detecting proximity to HeNBs with a short radio interface, setting a fictitious high RSRP value for stored HeNBs with the CSG Power parameter TRUE, allowing for immediate cell reselection or handover without waiting for measurement gaps, and using a CSG Power parameter to indicate switchable HeNBs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the radio section of HeNB is switched off when no UE is camping in it, then energy consumption and radio interference are reduced, but cell reselection and handover procedures fail when UE moves from macrocell to HeNB
Solution Approach 1:
The UE performs preliminary actions by storing HeNB information (cell ID, frequency, CSG ID) and maintaining a list of HeNBs with switched-off radio sections before actually needing to hand over. This allows the UE to quickly identify and connect to HeNBs without waiting for radio section activation, thus maintaining handover reliability while allowing energy-saving shutdown.
Solution Approach 2:
The patent introduces an intermediary mechanism where the UE uses stored HeNB information and proximity detection algorithms to mediate between the macrocell and the dormant HeNB. The UE can initiate handover procedures based on stored information even when the HeNB radio section is off, acting as an intermediary that bridges the connection gap.
2Measurement precision
If the UE waits for HeNB to be switched on before measuring RSRP, then accurate measurement can be performed, but handover is delayed causing disconnection
Solution Approach 1:
The UE performs preliminary actions by storing HeNB information (cell ID, frequency, CSG ID) and maintaining a list of HeNBs with switched-off radio sections before actually needing to hand over. This allows the UE to quickly identify and connect to HeNBs without waiting for radio section activation, thus maintaining handover reliability while allowing energy-saving shutdown.
Solution Approach 2:
The patent prepares cushioning measures in advance by maintaining a list of potential HeNBs with their basic information. When handover is needed, the UE can immediately start the connection process with pre-identified HeNBs, cushioning against the delay that would otherwise occur while searching for and measuring dormant HeNBs.
3Extent of automation
If the UE autonomously triggers cell reselection based on serving cell RSRP threshold, then mobility is automated, but the UE cannot detect HeNBs with switched-off radio sections
Solution Approach 1:
The UE performs preliminary actions by storing HeNB information (cell ID, frequency, CSG ID) and maintaining a list of HeNBs with switched-off radio sections before actually needing to hand over. This allows the UE to quickly identify and connect to HeNBs without waiting for radio section activation, thus maintaining handover reliability while allowing energy-saving shutdown.
Data Source
AI summary
The method comprises: a user equipment measuring its proximity to one or more cells, or radio access nodes, by detecting the signal emission power thereof, and recognizing some cells as distinctive cells which radio section can be switched off when no user equipment is camping in it; determining that at least one of said cells is candidate for cell reselection or handover as a function of said signal emission power, and, if the cell is a distinctive cell, directly determining it as a candidate cell even if its signal emission power is not detected; and performing the cell reselection or handover between the user equipment and the candidate cell.