RACH-PUSCH Occasion Mapping for Low-Latency Random Access
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Solution Overview
Problem
Existing wireless communication systems face challenges in optimizing the mapping patterns for random access procedures, particularly in two-step RACH procedures, leading to increased latency and reduced coverage due to the minimum transmission gap between preambles and uplink payloads.
Innovation Solution
The implementation of time-domain mapping patterns for RACH and uplink shared channel occasions, where UEs receive control signaling to transmit preambles and uplink payloads based on specific patterns, considering repetition levels and synchronization signal blocks, to enhance latency and coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a minimum transmission gap is maintained between preambles and uplink payloads, then transmission reliability is improved, but latency increases
Solution Approach 1:
The patent implements dynamic mapping patterns that adaptively adjust the timing relationship between RACH occasions and uplink shared channel occasions based on repetition levels. The system transitions from static gap requirements to dynamic timing adjustments, where the effective transmission gap is optimized according to channel conditions and repetition configurations, thereby reducing latency while maintaining reliability.
Solution Approach 2:
The patent changes key timing parameters by introducing different mapping patterns (e.g., pattern 1 and pattern 2) that define different time offsets between preamble and payload transmissions. By selecting appropriate mapping patterns based on repetition levels and channel conditions, the system optimizes the transmission timing to minimize latency while ensuring reliable delivery.
2Device complexity
If traditional mapping patterns are used for RACH occasions, then implementation simplicity is maintained, but coverage is reduced
Solution Approach 1:
The patent segments the uplink shared channel occasions into different types based on their mapping relationships with RACH occasions. By categorizing occasions into different mapping patterns and associating them with different repetition levels, the system creates a structured framework that extends coverage while maintaining manageable complexity through systematic classification.
Solution Approach 2:
The patent introduces an additional dimension to the mapping relationship by incorporating repetition levels into the mapping pattern selection. This creates a multi-dimensional mapping structure where occasions are not only mapped in time but also associated with specific repetition levels, thereby extending coverage without proportionally increasing implementation complexity.
3Loss of time
If multiple mapping patterns are implemented for different repetition levels, then latency is reduced, but device complexity increases
Solution Approach 1:
The patent implements dynamic selection of mapping patterns based on repetition levels, where the UE and network entity adaptively choose appropriate patterns (pattern 1 or pattern 2) according to the configured repetition level. This dynamic adaptation reduces latency for different channel conditions while keeping complexity manageable through rule-based selection rather than exhaustive processing.
Solution Approach 2:
The patent performs preliminary configuration of mapping patterns through control signaling from the network entity to the UE. By pre-configuring the mapping relationships and repetition level associations before actual transmission, the system prepares the timing structures in advance, reducing processing complexity during active communication while enabling optimized latency performance.
Data Source
AI summary
Methods, systems, and devices for wireless communication are described. A user equipment (UE) may receive control signaling indicating a time-domain mapping pattern between one or more random access occasions and one or more physical uplink shared channel (PUSCH) occasions. The UE may transmit one or more preambles of a random access message of a random access procedure in the one or more random access occasions in accordance with the time-domain mapping pattern. Additionally, the UE may transmit one or more PUSCHs (e.g., uplink payload transmissions) of the random access message in the one or more PUSCH occasions in accordance with the time-domain mapping pattern. In some examples, the UE may receive a random access response message based on a timing of the preamble and PUSCH transmissions.