HNB Mobility in Cell_FACH State via Extended Measurement
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Solution Overview
Problem
In UTRAN R9, Home NodeB (HNB) mobility in Cell_FACH state faces challenges such as insufficient time for WTRU to read MIB/SIB3 of target cells due to short FACH measurement occasions and potential data loss, as well as issues with unique U-RNTI assignment leading to incorrect context fetching and handling of mixed CSG and non-CSG neighbor cell lists.
Innovation Solution
The method involves a WTRU communicating an indication for extended measurement occasions to prevent data loss and ensure sufficient time to read MIB/SIB3, and implementing mechanisms to manage CSG membership and context fetching without CN involvement, including querying the core network for access control during cell reselection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If FACH measurement occasions are kept at fixed standard length, then network signaling complexity is reduced, but WTRU cannot acquire MIB/SIB3 of target HNB cell in time
Solution Approach 1:
The patent applies dynamics by making the FACH measurement occasion duration variable rather than fixed. The network node receives an indication from the WTRU about the required measurement time and configures the measurement occasion duration accordingly. This allows the measurement occasion to be extended when the WTRU needs more time to acquire MIB/SIB3 of a target HNB cell, while maintaining standard duration when not needed, thus resolving the contradiction between signaling complexity and acquisition time.
2Loss of information
If WTRU autonomously prolongs measurement occasions to read MIB/SIB3, then target cell information can be acquired, but data loss occurs at source HNB
Solution Approach 1:
The patent applies feedback by establishing a communication loop between the WTRU and the network node. The WTRU sends an indication to the network node about its measurement needs, and the network node responds by configuring appropriate measurement occasion parameters. This feedback mechanism ensures that the WTRU can acquire target cell information without autonomously prolonging measurements, as the network coordinates the measurement timing to prevent data loss at the source HNB.
3Productivity
If same U-RNTI is assigned to multiple WTRUs by different HNBs, then resource allocation is efficient, but context fetching becomes ambiguous
Solution Approach 1:
The patent applies the intermediary principle by introducing the HNB gateway as a mediating entity in the context fetching process. When a target HNB needs to fetch WTRU context, it sends the U-RNTI to the HNB gateway, which then identifies the source HNB and retrieves the appropriate context. This intermediary mechanism resolves the ambiguity caused by non-unique U-RNTI assignments while maintaining the efficiency of reusable U-RNTI resources across different HNBs.
Data Source
AI summary
Disclosed herein are systems and methods for managing home nodeB (HNB) mobility in forward access channel (Cell_FACH) states. According to an aspect, a method may be implemented at a Wireless Transmit/Receive Unit (WTRU). The method may include determining whether to communicate an indication to a network node for extended measurement occasion. Further, the method may include communicating the indication to the network node in response to determining to communicate the indication.