Contention Free Random Access Coverage Enhancement via Repeated Uplink Transmission
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Solution Overview
Problem
Current wireless communication systems face challenges in ensuring reliable transmission of uplink messages during contention-free random access (CFRA) procedures, particularly in maintaining coverage and reducing the likelihood of message failure.
Innovation Solution
The implementation of CFRA with coverage enhancement, where user equipment (UE) can request or be scheduled for repeated transmission of uplink messages (Msg3) based on reference signal measurements, using preambles and random access occasions configured for coverage enhancement, to increase the probability of successful reception by the base station.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If repeated transmission of uplink messages is implemented during CFRA procedures, then coverage and reliability are enhanced, but device complexity and signaling overhead increase
Solution Approach 1:
The network configures the UE with multiple preambles and random access occasions before the CFRA procedure begins. The UE determines in advance which preambles and occasions are associated with coverage enhancement based on reference signal measurements, eliminating the need for complex real-time decisions during the random access procedure.
Solution Approach 2:
The patent introduces an intermediary signaling mechanism where the UE indicates its coverage enhancement requirement to the network through preamble selection or random access occasion selection. The network then responds with appropriate configuration messages that guide the repeated transmission process, distributing the complexity between UE and network rather than concentrating it in one device.
2Reliability
If repeated transmission of uplink messages is implemented during CFRA procedures, then coverage and reliability are enhanced, but signaling overhead increases
Solution Approach 1:
The patent extracts the coverage enhancement indication from the main random access message payload and encodes it in the preamble selection or random access occasion selection itself. This allows the network to identify the need for repeated transmission without requiring additional signaling fields in the uplink message, thereby reducing signaling overhead.
Solution Approach 2:
The UE changes the parameter of preamble index or random access occasion index based on its coverage enhancement determination. By encoding the coverage requirement in the selection of these parameters rather than transmitting it explicitly, the system reduces the amount of signaling required while still conveying the necessary information to the network.
3Adaptability or versatility
If UE autonomously determines coverage enhancement based on reference signal measurements, then adaptability is improved, but measurement precision requirements increase
Solution Approach 1:
The patent provides the network with the ability to override or adjust the UE's autonomous determination of coverage enhancement. The network can configure specific thresholds or provide explicit indications that modify the UE's local decision-making, allowing the system to adapt to varying measurement conditions and network states without requiring extremely precise UE measurements alone.
Solution Approach 2:
The network receives measurement reports from the UE and provides feedback in the form of configuration messages that confirm or adjust the coverage enhancement parameters. This feedback loop allows the system to refine the coverage enhancement decision based on both UE measurements and network conditions, reducing the burden on UE measurement precision while maintaining adaptability.
Data Source
AI summary
Methods, systems, nodes, and devices for wireless communication are described. The method may include a first network node (e.g., a user equipment (UE)) receiving a first message that indicates a first preamble and transmitting a random access request message indicative of a request by the first network node for repetition based transmission of a second message. In response to the random access request, the first network node may receive a random access response message including an indication that the second message is to be transmitted with repetition and transmit the second message in accordance with repetition.