Light RRC Connection Transfer for Wireless Handover
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Solution Overview
Problem
In LTE systems, there is a lack of clarity on how to perform a seamless connection transfer of a user equipment (UE) from one evolved Node-B (eNB) to another, which affects the efficiency of radio and network interface signaling and power consumption.
Innovation Solution
The implementation of a system where a first base station determines the type of UE and configures it to a light RRC connected mode, generating specific connection transfer messages with system information tailored to the UE's type or coverage enhancement status, and transmits these messages to a second base station for efficient handover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a connection transfer is performed for a UE in CE via a cell of the first eNB, then the UE can maintain connectivity during handover, but the signaling overhead and complexity of the connection transfer procedure increases
Solution Approach 1:
The connection transfer procedure is segmented into distinct phases: preparing the target cell, executing the handover, and completing the connection transfer. This segmentation allows each phase to be optimized independently and reduces overall complexity by breaking down the complex handover process into manageable steps.
Solution Approach 2:
The target cell is prepared in advance before the actual handover occurs. The second eNB configures the target cell and sends preparation confirmation to the first eNB before the UE handover is executed. This preliminary action ensures that when handover is needed, the target cell is already ready, reducing the complexity and time required for the actual connection transfer.
2Reliability
If standard RRC connected mode is used for connection transfer, then complete control is maintained, but radio and network interface signaling overhead increases
Solution Approach 1:
The patent extracts and removes unnecessary signaling elements from the standard RRC connected mode procedure. By identifying and eliminating redundant signaling messages and parameters that are not essential for the handover process, the solution reduces signaling overhead while maintaining the necessary control functionality.
Solution Approach 2:
Instead of using full RRC connected mode with all its signaling, the patent applies partial action by implementing only the essential signaling required for connection transfer in CE mode. This partial approach maintains sufficient control for the handover while significantly reducing the overall signaling overhead and energy consumption.
3Reliability
If connection transfer messages include all system information, then complete configuration is provided, but message size and processing time increase
Solution Approach 1:
The patent applies local quality by tailoring the connection transfer messages to include only the specific system information relevant to the UE's current state and the target cell configuration. Instead of transmitting all system information universally, the solution customizes the message content based on the specific requirements of CE mode UEs and the actual handover scenario, reducing message size and processing time while maintaining necessary configuration completeness.
Data Source
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AI summary
A first base station (BS) for handling a connection transfer with a second BS comprises a storage unit for storing instructions and a processing circuit coupled to the storage unit. The processing circuit is configured to execute the instructions stored in the storage unit. The instructions comprise determining to configure a first communication device to be in a light radio resource control (RRC) connected mode; generating a first RRC message configuring the first communication device to be in the light RRC connected mode; generating a first connection transfer message comprising first system information, when the first communication device is in coverage enhancement (CE) or a type of the first communication device is a first type; and generating the first connection transfer message comprising second system information, when the first communication device is not in CE or the type of the first communication device is a second type.