Random Access Response Scheduling via Multiple PDCCHs
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Solution Overview
Problem
In LTE networks, multiple UEs attempting random access using the same PRACH resource have a low success rate due to the base station's inability to distinguish between them and return only one Random Access Response (RAR) on a single PDCCH, limiting the success rate of random access.
Innovation Solution
The base station detects the random access preamble sequence sent by UEs and determines the corresponding control channel based on configuration information, scheduling RARs using multiple types of PDCCHs, such as PDCCH and E-PDCCH, to differentiate and respond to each UE, even if they use the same PRACH sequence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the base station returns only one RAR on a single PDCCH for the same PRACH resource, then the system maintains simple control channel structure, but the random access success rate deteriorates when multiple UEs use the same PRACH resource
Solution Approach 1:
The patent segments the control channel resources by dividing PDCCH into multiple search spaces (common and dedicated) and further segmenting RAR responses by assigning different RA-RNTI values to different UEs. This segmentation allows multiple UEs to receive individualized RAR responses on the same PRACH resource, improving random access success rate while maintaining structured control channel organization.
Solution Approach 2:
The patent introduces additional dimensions for control channel differentiation beyond the single PDCCH approach. By adding RA-RNTI as a new dimension (derived from time-frequency resources and UE-specific parameters) and creating multiple search spaces, the system can address multiple UEs simultaneously on the same PRACH resource, resolving the contradiction between simplicity and success rate.
2Reliability
If multiple UEs send the same PRACH sequence, then the system maintains simple sequence selection process, but the base station cannot distinguish between UEs leading to low access success rate
Solution Approach 1:
The patent changes the parameter space for UE identification by deriving RA-RNTI from multiple parameters including time-frequency resource indices and UE-specific parameters (such as cell ID, subframe number, and PRACH resource index). This parameter transformation allows the base station to distinguish between UEs even when they send the same PRACH sequence, as each UE gets a unique RA-RNTI value for RAR reception.
Data Source
AI summary
Embodiments of the present invention provide a method and a device for processing random access. The method includes: detecting a random access preamble sequence which is sent by a user equipment UE according to configuration information; determining a control channel corresponding to the detected random access preamble sequence, and scheduling random access response information corresponding to the random access preamble sequence by using the control channel. Another method includes: sending a random access preamble sequence to a base station according to configuration information; detecting, on a control channel corresponding to the random access preamble sequence, scheduling information of random access response information which corresponds to the random access preamble sequence; and detecting the random access response information according to the scheduling information. In the embodiments of the present invention, as many different types of PDCCHs as possible can be used for RAR scheduling to avoid the problem that only one UE can receive an RAR, thereby improving the success rate of random access.