RAR-less Mobility Enhancing Solutions for 5G Handover
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current 5G wireless systems face challenges in reducing mobility interruption time during handover procedures, particularly for user equipment (UE) with a single transceiver, as they need to monitor random access responses and cannot exchange data with the source cell while sending preamble messages, leading to increased interruption times and potential retransmissions.
Innovation Solution
The proposed solution involves a method where the UE receives a command to send a preamble message to a target base station while continuing to exchange data with the source base station, temporarily detaching to synchronize with the target station, and resuming data exchange immediately after sending the preamble, with the option to skip uplink transmissions and receive random access responses via the source base station's radio link, allowing for coordinated time occasions to minimize interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE monitors random access response from the target base station while sending preamble messages, then the handover procedure follows the standard protocol, but the mobility interruption time increases and data exchange with the source cell must be suspended
Solution Approach 1:
The source base station pre-configures the UE with downlink configuration information and random access parameters before the actual handover execution. This preliminary configuration allows the UE to perform random access to the target cell without needing to monitor random access responses from the target during the handover process, thereby reducing mobility interruption time while maintaining protocol reliability
Solution Approach 2:
The source base station acts as an intermediary by forwarding handover command messages to the UE and providing the necessary configuration information. This intermediary role allows the UE to execute handover procedures without direct real-time interaction with the target base station during critical phases, reducing interruption time while ensuring reliable handover execution
2Productivity
If the UE exchanges data with the source base station while listening for random access response, then data exchange continuity is maintained, but the UE cannot properly monitor random access responses due to single transceiver constraints
Solution Approach 1:
The source base station provides downlink configuration information and random access parameters in advance through RRC messages before the UE needs to perform random access. This preliminary provision of configuration data allows the UE to maintain data exchange with the source while having all necessary parameters pre-loaded, eliminating the need to suspend data exchange for configuration purposes
Solution Approach 2:
The random access response monitoring function is extracted from the target base station and redirected to the source base station. The source base station monitors the random access preamble sent by the UE and provides the response, allowing the UE to continue data exchange with the source while the handover to target is being prepared, thus maintaining productivity without compromising reliability
3Reliability
If the UE temporarily detaches from the source base station to synchronize with the target base station, then synchronization with the target is achieved, but data exchange with the source is interrupted
Solution Approach 1:
The source base station pre-configures all necessary synchronization parameters, timing advance values, and random access parameters in the handover command message before the UE detaches. This preliminary configuration allows the UE to quickly synchronize with the target base station without needing to perform lengthy synchronization procedures, thereby achieving reliable target synchronization while minimizing data exchange interruption time
Solution Approach 2:
The UE dynamically switches its connection state from source to target base station based on the handover execution timing. The system allows the UE to maintain data exchange with the source during the preparation phase, then quickly transition to the target when synchronization is complete, optimizing both reliability and productivity through dynamic state management
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Systems, methods, apparatuses, and computer program products for random access response-less (RAR-less) mobility enhancing solutions are provided. One method may include exchanging packet data with a source base station. The method may also include receiving, from the source base station, a command to send a preamble message to a target base station and to listen for a random access response from the source base station. The method may further include continuing to exchange packet data with the source base station while listening for the random access response. The method may also include after receiving the command, temporarily detaching from the source base station and synchronizing with a target base station. In addition, the method may include sending the preamble message to the target base station according to a coordinated time occasion, and resuming packet data exchange with the source base station immediately after sending the preamble message.