Early Indicator for Fast Random Access in LTE
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Solution Overview
Problem
Current wireless communication systems face challenges in reducing latency and power consumption during random access procedures, particularly in LTE systems, where users and service providers demand faster and more efficient data transmission with reduced costs and improved service availability.
Innovation Solution
The method involves User Equipment (UE) receiving an indicator from the eNodeB indicating unsuccessful decoding of the Random Access Preamble (RAP), allowing the UE to stop monitoring the PDCCH and proceed to select a new random access resource within the same RAR window, thereby reducing unnecessary monitoring and enhancing the efficiency of the random access procedure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE continues monitoring PDCCH throughout the RAR window, then the reliability of random access response reception is improved, but the power consumption and latency increase
Solution Approach 1:
The eNB performs preliminary action by transmitting an indicator before the RAR window ends, informing the UE in advance that the RAP was not successfully decoded. This allows the UE to stop monitoring PDCCH early without compromising reliability, as the indicator provides advance notice of the decoding failure before the UE would have had to continue monitoring anyway.
Solution Approach 2:
The eNB provides feedback to the UE through the indicator signal, which conveys information about the RAP decoding status. This feedback mechanism allows the UE to adjust its monitoring behavior dynamically, stopping PDCCH monitoring when the indicator signals failure, thus reducing power consumption while maintaining reliable access through retransmission opportunities.
2Stability of the object's composition
If the UE waits for the RAR window to end before selecting a new random access resource, then the protocol compliance is improved, but the latency increases
Solution Approach 1:
The eNB transmits the indicator before the RAR window expires, providing advance information about the RAP decoding status. This preliminary action allows the UE to determine early whether to continue monitoring or proceed to resource selection, reducing the time the UE must wait while maintaining protocol compliance through structured decision-making points.
Solution Approach 2:
The random access procedure becomes dynamic rather than static. The UE's behavior changes based on real-time feedback from the indicator, allowing it to adapt its actions within the RAR window. This dynamic approach enables early termination of monitoring when failure is indicated, reducing latency while maintaining protocol compliance through flexible, condition-based resource selection.
3Reliability
If the UE monitors PDCCH continuously during RAR window, then the completeness of random access response is improved, but the processing time and power consumption increase
Solution Approach 1:
The indicator serves as feedback that informs the UE about the RAP decoding status before the RAR window ends. This feedback allows the UE to make informed decisions about whether to continue monitoring PDCCH or proceed to resource selection, reducing processing time while maintaining complete and reliable random access response through structured monitoring and decision points.
Data Source
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AI summary
The present invention relates to a wireless communication system. More specifically, the present invention relates to a method and a device for operating fast random access procedure in a wireless communication system, the method comprising: transmitting a RAP including a first RAP ID to an e-NodeB; starting monitoring a Physical Downlink Control Channel PDCCH addressed by RA-RNTI during RAR window; receiving, from the eNB, an indicator including at least one RAP ID, wherein one of the at least one RAP ID matches to the first RAP ID; and stopping monitoring the PDCCH addressed by RA-RNTI upon reception of the indicator.