UE SCell Random Access via PCell Mediation
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Solution Overview
Problem
In LTE-Advanced networks, user equipment (UE) performing contention-based random access channel (RACH) procedures on secondary cells (SCells) experiences increased blind detection times and false alarm probabilities due to the need to monitor common search spaces of multiple SCells.
Innovation Solution
The UE receives a physical random access channel resource subset from a base station, selects a preamble and PRACH resource on a first SCell, sends the preamble, generates a random access-radio network temporary identity, and receives scheduling information for random access response messages from a physical downlink control channel of a second SCell, thereby reducing the need to monitor multiple common search spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the UE performs contention-based RACH procedures on SCells by monitoring CSS of multiple SCells, then the RACH procedures can be completed on SCells, but the blind detection times and false alarm probability increase
Solution Approach 1:
The patent segments the RACH procedure into two distinct parts: (1) Preamble transmission on the SCell, and (2) Random Access Response reception on the PCell. This segmentation allows the UE to maintain RACH capability on SCell while avoiding the need to monitor CSS of multiple SCells, thereby reducing blind detection times and false alarm probability.
Solution Approach 2:
The patent introduces the PCell as an intermediary for receiving Random Access Response messages. Instead of requiring the UE to monitor CSS of multiple SCells, the PCell acts as a mediator that delivers the RAR messages back to the UE, eliminating the need for extensive blind detection across multiple SCell CSS while maintaining full RACH functionality.
2Adaptability or versatility
If the UE monitors CSS of multiple SCells for RACH procedures, then random access can be performed on SCells, but the processing complexity and time increase
Solution Approach 1:
The RACH procedure is segmented such that only the preamble transmission phase occurs on the SCell, while the response reception phase occurs on the PCell. This segmentation eliminates the need for the UE to monitor multiple SCell CSS, significantly reducing blind detection time while preserving SCell access capability.
Solution Approach 2:
The UE performs preliminary action by transmitting the preamble on the SCell first, then waits for the RAR message on the PCell. This preliminary preamble transmission allows the network to identify the UE's access request without requiring the UE to continuously monitor multiple SCell CSS, thereby reducing processing time.
3Productivity
If all RACH procedures are implemented on SCells, then carrier aggregation efficiency is improved, but the false alarm probability increases
Solution Approach 1:
The patent segments the RACH procedure to maintain carrier aggregation efficiency by allowing preamble transmission on SCell, while improving detection accuracy by relocating RAR reception to the PCell. This segmentation resolves the contradiction by separating the functions that require SCell involvement from those that benefit from PCell's more reliable monitoring.
Solution Approach 2:
The patent applies local quality by assigning different functional qualities to different cells: the SCell is optimized for preamble transmission (high productivity), while the PCell is optimized for RAR reception (high reliability). This localized functional assignment allows each cell to operate at its optimal quality level without compromising the other.
Data Source
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AI summary
The present invention provides a processing method and device for obtaining synchronization, where the method includes: selecting, by a UE, a Preamble on a first Scell, and reporting information of the Preamble to a base station by using a current PCell or a second SCell of the UE; receiving scheduling information of a random access response message or scheduling information of a conflict indication message delivered by the base station from a physical downlink control channel of the PCell, the second SCell or the first SCell by using a C-RNTI of the UE; and receiving the random access response message or the conflict indication message from a physical downlink shared channel according to the scheduling information of the random access response message or the scheduling information of the conflict indication message.