RRC Inactive TAU Indication to Avoid Double Area Updates
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Solution Overview
Problem
In wireless communication networks, particularly in the 5G system, UEs in RRC_INACTIVE state often trigger both Radio Access Network Notification Area Updates (RNAUs) and Tracking Area Updates (TAUs) simultaneously, leading to unnecessary transitions to RRC_CONNECTED state, which can result in inefficient network resource usage and potential context retrieval failures.
Innovation Solution
A coordinated procedure where UEs prioritize RNAUs over TAUs when crossing overlapping borders of tracking areas and RNA lists, and the network responds with RRC Resume messages to maintain UEs in RRC_INACTIVE unless a TAU is necessary, thereby avoiding double procedures and optimizing network resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If UE performs both RNAU and TAU simultaneously when crossing overlapping borders, then area coverage is improved, but network resource usage increases and context retrieval failures occur
Solution Approach 1:
The patent combines RNAU and TAU procedures into a single integrated update process. When a UE detects that it has crossed both RNA and TAI borders, the system merges both update types into one procedure, allowing the UE to perform a single RRC resume and send one TAU request that handles both area updates simultaneously, thereby reducing network resource usage while maintaining comprehensive area coverage
Solution Approach 2:
The TAU procedure is enhanced to serve multiple functions: it not only performs tracking area update but also simultaneously handles radio access network notification area update. The modified TAU request message and network response mechanisms enable a single procedure to address both RNAU and TAU requirements, making the update process universal and efficient
2Reliability
If UE transitions to RRC_CONNECTED state for both RNAU and TAU, then update reliability is improved, but connection establishment time increases
Solution Approach 1:
The system performs preliminary determination of whether a TAU is actually needed before initiating the full update procedure. The UE and network exchange preliminary messages to assess if the UE has truly crossed TAI borders, allowing the system to prepare for efficient processing while avoiding unnecessary full connection establishment if the update is not required
Solution Approach 2:
The patent maintains continuity of useful action by keeping the RRC connection in a suspended state during the update process. The UE can perform area updates while remaining in RRC_INACTIVE state with the connection suspended, allowing the network to process update requests efficiently without requiring complete connection establishment and teardown for each update type
Data Source
AI summary
Embodiments include methods performed by an access network node configured to operate in a wireless communication system. Such methods include receiving, from a wireless device via a cell, a Radio Resource Control (RRC) Resume Request message that includes a cause indicator indicating mobility signaling as a cause for the wireless device resuming an RRC Connected state. Such methods include retrieving a context for the wireless device. The context includes a tracking area identifier (TAI) list for the wireless device. Such methods include determining whether a tracking area code (TAC) of the cell is represented in the TAI list and when it is determined that the TAC is not represented in the TAI list, responding to the RRC Resume Request message with an RRC Resume message. Other embodiments include complementary methods for a wireless device as well as access network nodes and wireless devices configured to perform such methods.