Random-access occasion selection for reduced-capability user equipment
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Solution Overview
Problem
Half-duplex reduced-capability user equipment (RedCap) UEs face challenges in selecting random-access occasions (ROs) due to insufficient time to transition from receive to transmit mode, leading to delayed random-access procedures.
Innovation Solution
RedCap UEs receive system information mapping synchronization signal blocks (SSBs) to ROs and select an RO based on a duration threshold, ensuring sufficient time for transition, allowing efficient random-access procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If half-duplex RedCap UEs use conventional random-access occasion selection, then the random-access procedure can be initiated, but the UE cannot complete transmission in time due to insufficient transition time from receive to transmit mode
Solution Approach 1:
The patent applies preliminary action by pre-calculating and identifying suitable random-access occasions that satisfy the threshold duration requirement before actual random-access transmission. The UE determines the duration between latest received downlink transmission and each RO in advance, filters ROs that meet the threshold, and selects from the valid subset, ensuring sufficient transition time is guaranteed before transmission begins.
Solution Approach 2:
The patent changes the selection criterion parameter from conventional SSB-based selection to duration-based selection. By introducing a threshold duration parameter that compares the time between latest downlink transmission and RO against a minimum required transition time, the system adapts the random-access occasion selection to accommodate half-duplex UEs' switching requirements.
2Reliability
If the UE waits for sufficient transition time before transmitting random-access preamble, then mode switching can be completed reliably, but the random-access procedure is delayed
Solution Approach 1:
The system performs preliminary filtering of random-access occasions to identify those that inherently satisfy the threshold duration requirement. By pre-identifying valid ROs that already provide sufficient transition time, the UE can immediately transmit without additional waiting, thus maintaining both reliability and productivity.
Solution Approach 2:
The patent introduces dynamic adaptation by adjusting the random-access occasion selection based on the UE's half-duplex operational characteristics. The system dynamically determines which ROs are valid based on the threshold duration criterion, allowing flexible adaptation to different downlink transmission timing while maintaining reliable mode transitions.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. The described techniques relate to improved methods, systems, devices, and apparatuses that support random-access occasion (RO) selection for reduced-capability (RedCap) user equipment (UEs). A RedCap UE operating in a half-duplex mode may use the techniques described herein to efficiently select an RO in which to transmit a random-access preamble based on a duration between a latest received downlink transmission and the RO satisfying a threshold duration. The UE may receive system information mapping a set of synchronization signal blocks (SSBs) to a set of ROs. The UE may then select an RO from the set of ROs in which to transmit the random-access preamble such that the UE has sufficient time to transition from a receive mode to a transmit mode to transmit the random-access preamble.