RAR Message Transmission via Physical Downlink Control Channel
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Solution Overview
Problem
The 5G communication system's random access channel (RACH) procedure is inefficient, requiring significant time and resources for UE to establish an RRC layer connection, particularly due to delays in decoding the random access response (RAR) message and resource allocation.
Innovation Solution
The RACH procedure is optimized by masking the RAR message with a unique RA-RNTI value, allowing its transmission through a physical downlink control channel instead of a shared channel, reducing decoding time and resource usage, and simplifying the interface between schedulers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the RAR message is transmitted through the physical downlink shared channel, then the message can be delivered to the UE, but the decoding time and resource usage increase
Solution Approach 1:
The patent extracts the RAR message transmission from the physical downlink shared channel and relocates it to the physical downlink control channel. This separation allows the RAR message to be handled through a dedicated control channel pathway, reducing the decoding complexity and time required when using the shared data channel.
Solution Approach 2:
The patent introduces RA-RNTI (Random Access Radio Network Temporary Identifier) as an intermediary masking mechanism. By masking the RAR message with RA-RNTI, the system enables efficient identification and decoding at the UE side through the control channel, reducing the computational resources and time needed compared to unmasked transmission through the shared channel.
2Ease of operation
If the RACH procedure uses standard RAR message transmission, then the procedure is well-defined, but the interface complexity between schedulers increases
Solution Approach 1:
The patent merges the RAR message transmission function into the physical downlink control channel, which is already responsible for control information delivery. This consolidation eliminates the need for separate scheduling interfaces between data and control channels, simplifying the overall scheduler architecture while maintaining the established RACH procedure flow.
3Reliability
If downlink resources are allocated for RAR message transmission, then the UE can receive the response, but the resource consumption increases
Solution Approach 1:
The patent leverages the physical downlink control channel's existing multi-functional capability to also carry the RAR message. By making the control channel universal enough to handle both control information and random access responses, the system avoids allocating additional dedicated downlink resources, thereby reducing overall resource consumption while maintaining reliable response delivery.
Data Source
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AI summary
The disclosure relates to a pre-5th-generation (5G) or 5G communication system to be provided for supporting higher data rates beyond 4th-generation (4G) communication system such as long term evolution (LTE). According to an embodiment of the present disclosure, when a base station performs a random access channel (RACH) procedure with a terminal, the base station can receive a random access (RA) preamble from the terminal, generate a random access response (RAR) message including an uplink grant allocated to the terminal, allocate a physical downlink control channel resource through which the generated RAR message is to be transmitted, transmit the RAR message to the terminal through the allocated physical downlink control channel resource, and receive a radio resource control (RRC) layer connection request message from the terminal through a resource allocated to the terminal by the uplink grant. The present research has been conducted with support from the "Cross-Departmental Giga-KOREA Project" funded by the government (Ministry of Science and ICT) in 2017(No.GK17N0100, development of a millimeter wave 5G mobile communication system).