Secondary Cell Random Access Using Primary Cell Information
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Solution Overview
Problem
Legacy UE systems perform random access only on the Primary Cell (PCell), leading to uplink performance degradation in Secondary Cells (SCells), especially when PCell and SCells have different uplink transmission timings, and increase implementation complexity.
Innovation Solution
A method and apparatus that allow UE to perform random access in SCells, reuse information from PCell random access for SCell random access, and measure/notify mobility information during RRC connection release and reestablishment, improving SCell uplink performance and reducing complexity by reusing PCell information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE performs random access only on the PCell, then the PCell uplink transmission is reliable, but the SCell uplink performance degrades and may fail when PCell and SCells have different uplink transmission timings
Solution Approach 1:
The patent applies the copying principle by allowing the UE to reuse the random access information (such as timing advance, preamble, and other parameters) obtained from the PCell random access procedure for the SCell random access procedure. Instead of performing a completely independent random access on the SCell, the UE copies and adapts the PCell's random access information to the SCell context, thereby reducing implementation complexity while improving SCell uplink transmission reliability.
2Productivity
If the UE reuses PCell random access information for SCell random access, then SCell uplink performance improves and implementation complexity is reduced, but the SCell and PCell have different uplink transmission timings that must be handled
Solution Approach 1:
The patent applies the local quality principle by allowing different timing advance values to be applied to different cells (PCell and SCell) based on their specific characteristics. The UE maintains separate timing advance information for each cell, allowing the SCell to have its own specific timing alignment independent of the PCell. This enables each cell to have optimized local timing properties while still reusing the overall random access procedure framework.
Data Source
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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.