Mobile Terminal RRC Connection Failure Prevention
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Solution Overview
Problem
In Universal Mobile Telecommunications Systems (UMTS), mobile terminals face successive call connection failures due to network conditions like congestion, as they cannot determine when a Base Station (BS) is unable to perform a Radio Resource Control (RRC) connection, leading to repeated failed call attempts.
Innovation Solution
A method and apparatus that monitor the frequency of RRC connection reject messages to determine if a BS is capable of performing a connection, and if it is not, the mobile terminal reselects a neighboring cell with the highest RX power and transmits a new RRC Connection Request message.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the mobile terminal continuously transmits RRC Connection Request messages to the same BS despite rejection, then the terminal maintains simple call connection logic, but the call connection success rate deteriorates due to network congestion
Solution Approach 1:
The mobile terminal monitors the RRC connection reject message frequency from the BS and uses this feedback information to dynamically adjust its call connection strategy. When reject frequency exceeds a threshold, the terminal switches to selecting neighboring cells, thereby resolving the contradiction between simple logic and connection success rate
Solution Approach 2:
The call connection method transitions from a static approach (always selecting the same cell with highest RX power) to a dynamic approach (switching between serving cell and neighboring cells based on reject message frequency), improving reliability while maintaining operational simplicity through adaptive behavior
2Ease of operation
If the mobile terminal repeatedly attempts call connection to the same BS, then the terminal maintains simple access logic, but uplink interference increases due to successive failed attempts
Solution Approach 1:
The terminal uses feedback from reject message frequency monitoring to determine when to switch access targets, reducing unnecessary repeated access attempts that cause uplink interference while keeping access logic simple through threshold-based decision making
Solution Approach 2:
The terminal performs preliminary monitoring of reject message frequency before making access decisions, allowing it to proactively avoid BSs with high rejection rates and thereby prevent unnecessary uplink interference from failed connection attempts
3Reliability
If the mobile terminal continuously monitors network condition, then the call connection reliability improves, but the energy consumption increases
Solution Approach 1:
The terminal monitors reject message frequency rather than continuously monitoring all network parameters, achieving sufficient reliability information at reduced energy cost by focusing on the specific metric that indicates network accessibility
Solution Approach 2:
The terminal uses passively received RRC connection reject messages for monitoring purposes rather than actively querying network status, obtaining reliability information without additional energy-consuming transmission operations
Data Source
AI summary
Provided is an apparatus and method for preventing successive failures in a call connection in a mobile communication terminal. When a call connection is attempted, a cell with the highest RX power is selected among cells and an RRC Connection Request message is transmitted from the mobile terminal to a BS of the selected cell. It is determined whether the mobile terminal receives an RRC Connection Accept/Reject message from the BS. If the mobile terminal receives an RRC Connection Reject message from the BS of the selected cell, it is determined whether the selected cell is able to perform the RRC connection by detecting a Connection Reject message frequency that is the number of times of rejection of an RRC connection request for a predetermined period. If the selected cell is not able to perform the RRC connection, a neighboring cell is reselected and an RRC Connection Request message is transmitted to the reselected neighboring cell.