Random Access Procedure for Multiple Uplink Timing Advances
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Solution Overview
Problem
Conventional random access protocols in LTE-A systems with Carrier Aggregation (CA) fail to effectively manage multiple uplink timing advances, limiting the ability to perform random access procedures in scenarios where different cells have distinct timing advances, especially for Secondary Cells (SCells).
Innovation Solution
The method involves designating a carrier for each message during the random access procedure, allowing the network side to initiate and the UE to perform random access on a designated carrier, ensuring that the random access procedure can be executed in scenarios with multiple uplink timing advances by coordinating the transmission of Msg0, Msg1, Msg2, Msg3, and Msg4 messages across different carriers, using cross-carrier scheduling and Carrier Indication Fields (CIF) to maintain synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional random access protocol is used in LTE-A with Carrier Aggregation, then compatibility with LTE system is maintained, but the ability to manage multiple uplink timing advances is insufficient
Solution Approach 1:
The patent segments the random access procedure by carrier, introducing carrier-specific Msg0, Msg1, Msg2, and Msg4 for each cell in the CA configuration. This segmentation allows independent timing advance management for each carrier while maintaining overall system compatibility, resolving the contradiction between versatility and reliability.
Solution Approach 2:
The patent applies local quality by enabling each carrier to have its own specific random access parameters and timing advance values. The Msg0 for each carrier includes carrier-specific PRACH configuration, and each carrier maintains its own timing advance independently, allowing optimized performance for each local carrier while supporting multi-TA scenarios.
2Adaptability or versatility
If single carrier random access is used, then protocol simplicity is maintained, but multi-TA scenario support is limited
Solution Approach 1:
The patent implements universality by designing a unified random access framework that works across multiple carriers simultaneously. The same basic random access procedure (Msg0-Msg4) is applied to each carrier, with each carrier's Msg0 containing references to other carriers' configurations. This multi-functional design enables multi-TA support while maintaining procedural consistency, balancing versatility with manageable complexity.
Solution Approach 2:
The patent employs nesting by having each carrier's Msg0 contain references to other carriers' PRACH configurations and timing advance information. The random access procedure for one carrier is nested within the context of other carriers, allowing compact representation of multi-carrier dependencies without proportionally increasing complexity.
3Ease of operation
If cross-carrier scheduling is implemented, then random access flexibility is improved, but message transmission coordination becomes more complex
Solution Approach 1:
The patent uses Msg0 as an intermediary message that coordinates between carriers. Each carrier's Msg0 contains references to other carriers' configurations, acting as a mediator that establishes the cross-carrier scheduling relationships. This intermediary approach simplifies coordination by centralizing the reference information in Msg0 rather than requiring complex direct coordination between all carriers.
Data Source
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AI summary
Disclosed are a random access method and apparatus based on multiple uplink timing advances. The method includes: when acquiring that a user equipment has multiple uplink timing advances, initiating, by a network side, for the user equipment a random access on a designated carrier of a secondary cell. According to the examples, random access in the SCell can be realized in scenarios that multi-TA is maintained.