UE Random Access in Secondary Cells via PCell Information Reuse
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Solution Overview
Problem
Legacy UE systems perform random access only in the Primary serving cell (PCell), leading to uplink performance degradation in Secondary serving cells (SCells) due to different uplink transmission timings, and increase implementation complexity by requiring separate random access procedures.
Innovation Solution
A method and apparatus that enable UE to perform random access in SCells, reusing information from PCell random access procedures, allowing for improved SCell uplink performance and reduced complexity by allowing UE to measure and notify mobility information during RRC connection release and reestablishment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If random access is performed only in PCell, then implementation complexity is reduced, but SCell uplink performance deteriorates due to different uplink transmission timings
Solution Approach 1:
The patent merges the random access procedures of PCell and SCell by allowing the UE to perform random access in both cells simultaneously or sequentially. The UE reuses the random access information (such as preamble, timing advance, and resource allocation) obtained from PCell random access for SCell random access, thereby maintaining SCell uplink performance while avoiding the need for completely separate random access procedures.
Solution Approach 2:
The patent makes the random access information universal across multiple cells. The random access parameters configured for PCell are made applicable to SCell as well, allowing the same random access procedure to serve multiple functions (both PCell access and SCell access). This multi-functionality reduces implementation complexity while maintaining SCell performance.
2Reliability
If separate random access procedures are implemented for PCell and SCell, then SCell uplink performance is improved, but device complexity increases
Solution Approach 1:
The patent performs preliminary random access in PCell first, obtaining random access information such as timing advance and preamble configuration. This preliminary action in PCell prepares the UE for subsequent SCell random access by providing reusable information, thereby improving SCell uplink performance without requiring completely separate random access procedures for each cell.
Solution Approach 2:
The patent copies the random access information obtained from PCell and applies it to SCell random access. Instead of implementing entirely separate random access procedures, the UE copies relevant parameters (preamble, timing advance, resource allocation) from PCell and reuses them for SCell, thereby maintaining SCell performance while reducing the complexity of implementing separate procedures.
3Device complexity
If random access information is reused from PCell for SCell, then implementation complexity is reduced, but measurement precision for SCell may deteriorate
Solution Approach 1:
The patent applies local quality by allowing the UE to reuse random access information from PCell for SCell when channel conditions are similar, but to perform separate measurements and adjustments when local conditions differ. The UE monitors SCell-specific channel quality and adjusts random access parameters locally for SCell based on measured conditions, thereby maintaining measurement precision while reducing overall implementation complexity through selective information reuse.
Data Source
AI summary
A data transmission method and an apparatus to communicate data on multiple carriers in the mobile communication system are provided. A random access method of a terminal in a mobile communication system including primary and secondary cells operating on multiple carriers according to the present invention includes communicating data after random access in the primary cell, receiving, when the random access is triggered in the secondary cell, information for use in the secondary cell random access from the primary cell, transmitting a preamble in the secondary cell based on the received information, monitoring the primary cell to receive a Random Access Response for the secondary cell, and applying, when the Random Access Response for the secondary cell is received, the information carried in the Random Access Response to the secondary cell in which the preamble has been transmitted.