Context Reuse for Fast RRC Connection in LTE
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Solution Overview
Problem
In LTE systems, frequent signaling occurs during transitions between RRC idle and connected states, and there is a lack of efficient methods for a base station to determine whether user equipment retains context information for connection establishment by reusing retained context.
Innovation Solution
User equipment and base stations implement a messaging system where the user equipment transmits a message indicating retained context information, and the base station responds with associated context information, allowing for connection establishment using reused context.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE transitions between RRC idle state and RRC connected state using traditional signaling procedures, then connection establishment is achieved, but signaling overhead increases and latency increases
Solution Approach 1:
The UE retains UE context information (including security information, bearer information, and radio resource configuration) in idle state before transition to connected state. The eNB also retains corresponding context information. This preliminary retention of context information enables faster connection establishment without full signaling exchange, reducing latency while maintaining connection reliability.
Solution Approach 2:
The patent introduces a context retention indicator parameter that changes the state of context information retention. When this parameter indicates retention, the UE and eNB can reuse existing context information instead of performing complete signaling procedures, thereby reducing signaling overhead and latency while maintaining reliable connection establishment.
2Loss of energy
If the UE retains UE context information in idle state for connection reuse, then signaling overhead is reduced, but the eNB cannot determine whether the UE retains valid context information
Solution Approach 1:
The patent uses a context retention indicator (acting as a signal or 'color' change) to indicate whether the UE retains valid context information. When the UE has valid context information, it sets this indicator; when transitioning to connected state, the eNB can detect this indicator to determine whether to proceed with context reuse or perform full authentication and setup procedures.
Solution Approach 2:
The eNB provides feedback by monitoring the context retention indicator from the UE and determining whether to accept context reuse. This feedback mechanism allows the eNB to verify the validity of retained context information without requiring complete re-authentication, thereby reducing signaling overhead while maintaining system reliability.
Data Source
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AI summary
Provided is user equipment of a mobile communication system that supports a function for establishing a connection by reusing context information retained in each of the user equipment and a base station, the user equipment including a transmitter that transmits, to the base station, a first message indicating that the user equipment retains user equipment side context information; a receiver that receives, from the base station, a second message indicating that the base station retains base station side context information associated with the user equipment; and a connecting unit that establishes a connection with the base station using the user equipment side context information after receiving the second message.