5G Terminal Random Access Preamble for RedCap Identification
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Solution Overview
Problem
In wireless communication systems, particularly in 5G NR, there is a lack of specification for identifying terminals like RedCapUE or CovEnhUE during the random access procedure, specifically at the time of PRACH transmission, which hinders effective coverage enhancement and resource allocation.
Innovation Solution
A terminal is configured with a receiver to obtain system information, a controller to select appropriate resources for random access based on the terminal type, and a transmitter to send a random access preamble using those resources, allowing identification as a reduced-function or enhanced-coverage terminal type.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coverage enhancement techniques are applied to Msg3 in random access procedure, then coverage enhancement is achieved, but terminal identification at the time of PRACH transmission becomes unspecified and problematic
Solution Approach 1:
The terminal transmits its type information (RedCapUE or CovEnhUE) during the PRACH transmission phase, before the actual random access procedure progresses to Msg3. This preliminary identification allows the base station to prepare appropriate coverage enhancement configurations in advance, eliminating the need for complex identification mechanisms later in the procedure.
Solution Approach 2:
The random access procedure is segmented into distinct phases with specific identification functions. Terminal type identification is separated from general random access signaling by introducing dedicated indication fields (such as specific preamble sequences or uplink signal configurations) that carry type information independently, allowing the base station to handle different terminal types with specialized procedures.
2Ease of operation
If general random access procedures are used without terminal type identification, then procedure simplicity is maintained, but resource allocation efficiency and coverage enhancement capability deteriorate
Solution Approach 1:
The random access preamble and uplink signal structures are designed with multi-functionality, serving both as standard access signals and as terminal type indicators. For example, specific preamble sequences or PRACH resource selections simultaneously perform the dual function of initiating random access and identifying the terminal as RedCapUE or CovEnhUE, eliminating the need for separate identification signaling.
Solution Approach 2:
The terminal autonomously selects and transmits type-specific parameters (such as choosing from predefined sets of time/frequency resources or preamble groups based on its type) without requiring explicit base station configuration for each terminal type. This self-service approach maintains procedure simplicity while enabling efficient type-based resource allocation.
Data Source
AI summary
A terminal includes a receiver configured to receive system information including information pertaining to random access procedures from the base station; a controller configured to select the resources to be used for random access based on the information pertaining to the random access procedure and a device type of the terminal acting as a reference terminal; and a transmitter configured to transmit a random access preamble to the base station using the selected resource, wherein the device type of the reference terminal is a reduced-function terminal type or an enhanced-coverage terminal type.