UE Random Access Subframe Configuration for Dual Connectivity
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Solution Overview
Problem
In heterogeneous LTE networks, UEs supporting dual connectivity face challenges in ensuring the success of random access procedures due to timing requirements for MSG3/MSG1 transmissions, which often fall outside the designated subframes for communications with the secondary base station, leading to potential handover failures.
Innovation Solution
Modifying the LTE random access procedure timing requirements to ensure that MSG3/MSG1 transmissions occur within the assigned subframes for communications with the secondary base station, by obtaining and utilizing subframe configurations from the primary base station to perform random access operations based on specific timing adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If UEs support dual connectivity at Layer 2 and Layer 3 with TDM scheme, then the UE can communicate with both Macro eNB and pico eNB, but the random access timing requirements cannot be satisfied leading to handover failure
Solution Approach 1:
The patent makes the subframe configuration dynamic by allowing the network to configure different subframe sets for different base stations. The UE can adaptively determine which subframes are available for random access to the second base station based on the configured subframe sets, enabling flexible time-division multiplexing between multiple base stations while satisfying timing requirements.
Solution Approach 2:
The patent segments the uplink subframes into different sets, where each set is associated with a specific base station. This segmentation allows the UE to perform random access to the second base station using only the subframes allocated to that base station, ensuring timing requirements are met while maintaining dual connectivity capability.
2Manufacturing precision
If strict timing requirement for MSG3/MSG1 transmission is enforced, then random access procedure specification is followed, but TDM type UE cannot guarantee successful random access in dual connectivity scenario
Solution Approach 1:
The patent changes the parameter of subframe availability by configuring subframe sets that indicate which uplink subframes are valid for random access to the second base station. This parameter change allows the system to maintain strict timing requirement compliance while adapting to TDM operation modes, ensuring both specification adherence and random access success.
3Adaptability or versatility
If subframes are split into two sets for TDM operation, then communication with multiple base stations is enabled, but random access timing may fall outside assigned subframes
Solution Approach 1:
The patent introduces subframe configuration as an intermediary mechanism that mediates between the TDM scheduling requirements and random access timing requirements. The network configures subframe sets that act as a bridge, indicating to the UE which subframes are valid for random access to the second base station, thereby aligning timing without sacrificing multi-base station communication capability.
Data Source
AI summary
The present disclosure relates to a method used in a UE for performing a random access to a second base station and an associated UE. The UE has been in communications with a first base station. The method includes: obtaining from the first base station a subframe configuration for the UE, which indicates a first set of subframes assigned to communications between the UE and the first base station and a second set of subframes assigned to communications between the UE and the second base station; and performing the random access to the second base station based on the subframe configuration. The present disclosure also relates to a method used in a second base station for establishing a connection with a UE and an associated second base station.