PDCCH Repetition for 5G Random Access Reliability
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Solution Overview
Problem
Current wireless communication systems face challenges in ensuring reliable decoding of random access response messages, particularly in scenarios where the physical downlink control channel (PDCCH) messages are prone to errors due to high path loss, leading to bottlenecks in 5G NR coverage, especially at millimeter-wave frequencies.
Innovation Solution
The implementation of PDCCH repetition across multiple monitoring occasions, where the base station transmits multiple copies of the Msg2 PDCCH message using different radio network temporary identifiers (RNTIs) and alternative control resource sets, allowing user equipment (UE) to perform soft combination and improve signal-to-interference-plus-noise ratio (SINR) for successful decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PDCCH messages are transmitted without repetition, then device complexity and signaling overhead are kept low, but decoding reliability deteriorates in high path loss environments
Solution Approach 1:
The patent transmits multiple copies of the PDCCH message (repetition transmissions) to improve decoding reliability. The UE receives multiple copies of the same PDCCH message across different monitoring occasions and combines them to achieve reliable decoding, directly addressing the reliability improvement while managing complexity through standardized combination procedures.
Solution Approach 2:
The patent configures the UE with multiple RNTI values in advance before the random access procedure. This preliminary configuration allows the UE to efficiently monitor and decode repeated PDCCH messages without requiring complex real-time processing, thereby improving reliability while controlling device complexity.
2Length of stationary object
If PDCCH repetition is implemented across multiple monitoring occasions, then coverage is enhanced, but loss of time increases due to extended random access response window
Solution Approach 1:
The patent pre-configures the UE with multiple RNTI values and repetition parameters before the random access procedure begins. This allows the UE to efficiently monitor for repeated PDCCH transmissions across multiple monitoring occasions without requiring extended processing time, thereby enhancing coverage while minimizing time loss.
Solution Approach 2:
The patent implements periodic repetition of PDCCH messages across multiple monitoring occasions with defined intervals. This structured periodic transmission allows the UE to accumulate signal energy over time to extend coverage, while the regular pattern enables efficient time management and prevents excessive delay.
3Reliability
If multiple RNTI values are used for PDCCH repetition, then decoding reliability is improved, but device complexity increases due to additional identifier management
Solution Approach 1:
The patent pre-configures the UE with multiple RNTI values (e.g., RA-RNTI, TC-RNTI, C-RNTI) before the random access procedure. This preliminary configuration allows the UE to efficiently manage multiple identifiers without complex real-time processing, improving decoding reliability while controlling device complexity through standardized procedures.
Solution Approach 2:
The patent makes the UE capable of using multiple RNTI values for different purposes within the random access procedure. Each RNTI serves a specific function (initial access, contention resolution, etc.), allowing the system to improve reliability through diverse identifier usage while managing complexity through specialized, standardized handling of each RNTI type.
Data Source
AI summary
Aspects relate to random access procedures. A base station may transmit a random access response message to a user equipment (UE) on a downlink control channel at a first monitoring occasion and transmit at least one repetition of the random access message at at least one offset from the first monitoring occasion. The base station may also transmit an indication of the offset(s) to the UE. Upon receiving the indication of the offset(s), the UE may monitor for the random access response message on the downlink control channel at the first monitoring occasion and at the monitoring occasion(s) for the repetition(s). A UE may identify a first radio network temporary identifier (RNTI) used to affect a physical downlink control channel (PDCCH) sent within a random access response (RAR) window and determine based on the first RNTI that the PDCCH is one of a plurality of PDCCH repetitions.