Random Access Channel Association for Msg2 Overhead Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The separation of random access channel (RACH) occasions (ROs) between different types of user equipment (UEs) leads to higher Msg2 overhead, including physical downlink control channel (PDCCH) overhead and physical downlink shared Channel (PDSCH) overhead, which deteriorates the random access (RA) performance of other types of UEs, such as legacy eMBB or URLLC UEs.
Innovation Solution
The method involves determining an association between a first RO and a second RO, where the second RO is configured for a different type of UE and is not earlier than the first RO in the time domain, with the association based on synchronization signal blocks (SSBs), allowing for shared Msg2 transmission with appropriate scrambling sequences and RA response windows, thereby reducing overhead and improving RA performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ROs are separated between different types of UEs, then RA performance for specific UE types is improved, but Msg2 overhead increases and RA performance for other UE types deteriorates
Solution Approach 1:
The patent combines Msg2 resources for different UE types by establishing associations between ROs of different UE types. Specifically, a first RO for a first UE type is associated with a second RO for a second UE type, allowing the base station to transmit Msg2 for the first UE type using the second RO's resources. This merging approach reduces overall Msg2 overhead while maintaining dedicated RA performance for different UE types.
Solution Approach 2:
The patent makes Msg2 resources universal by enabling a single Msg2 transmission to serve multiple UE types through RO association. The second RO is configured to handle Msg2 for both the second UE type and the first UE type, creating multi-functional resource usage that reduces overhead while supporting diverse UE requirements.
2Reliability
If ROs are separated between different types of UEs, then RA performance for specific UE types is improved, but PDCCH overhead increases
Solution Approach 1:
The patent merges PDCCH resources by associating ROs across different UE types. When a first RO for a first UE type is associated with a second RO for a second UE type, the PDCCH for Msg2 can be transmitted using the second RO's time-frequency resources, reducing the total number of PDCCH transmissions required while maintaining reliable RA for both UE types.
3Reliability
If ROs are separated between different types of UEs, then RA performance for specific UE types is improved, but PDSCH overhead increases
Solution Approach 1:
The patent combines PDSCH resources through RO association mechanisms. By associating a first RO for a first UE type with a second RO for a second UE type, the PDSCH carrying Msg2 can be transmitted using the second RO's resources, reducing PDSCH overhead while ensuring reliable delivery to both UE types.
Data Source
AI summary
Disclosed are methods and apparatuses for small data transmission in random access. One embodiment of the subject application provides a method performed by a user equipment, including determining an association among a first random access channel (RACH) occasion (RO), a preamble, and a second RO, and receiving an random access response (RAR) in an Msg2 at least according to the second RO in response to transmitting the preamble in the first RO.