Uplink Sequence Length Adaptation for 5G NR-U Coexistence
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Solution Overview
Problem
Current 5G NR-U systems face challenges in efficiently managing uplink transmissions to coexist with other radio access technologies like Wi-Fi, particularly in terms of occupied channel bandwidth, energy detection thresholds, and initial access procedure latency, which affect resource efficiency and channel access probability.
Innovation Solution
The system configures different sequence lengths for uplink transmissions based on conditions such as occupied channel bandwidth and UE capability, allowing dynamic selection of sequence lengths and energy detection thresholds to optimize resource usage and reduce signaling overhead, and introduces a two-step RACH procedure to enhance initial access efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed sequence length is used for uplink transmissions, then the system operation is simple, but the resource efficiency is poor under varying channel conditions
Solution Approach 1:
The patent implements dynamic sequence length selection where the UE can choose between first and second sequence lengths based on channel conditions and occupancy status. This dynamic adaptation allows the system to optimize resource efficiency by using longer sequences when channels are occupied and shorter sequences when channels are free, without requiring complex centralized control
Solution Approach 2:
The UE autonomously determines whether to use the first or second sequence length based on local channel occupancy detection and configured parameters. This self-service mechanism eliminates the need for complex network-side control and signaling, achieving adaptability while keeping system complexity low
2Reliability
If longer sequence lengths are used for uplink transmissions, then the channel access probability improves, but the access latency increases
Solution Approach 1:
The patent changes the sequence length parameter dynamically based on channel occupancy conditions. When the channel is detected as occupied, the UE uses the first (longer) sequence length to improve detection reliability and channel access probability. When the channel is free, the UE switches to the second (shorter) sequence length to minimize access latency. This parameter adaptation resolves the contradiction between reliability and time loss
3Productivity
If dynamic sequence length selection is implemented, then the resource efficiency improves, but the signaling overhead increases
Solution Approach 1:
The patent extracts the sequence length selection decision from the network-side control plane and places it at the UE side based on local observations. The network only provides configuration parameters (first sequence length, second sequence length, threshold values), but the actual selection is made autonomously by the UE based on channel occupancy detection. This extraction eliminates continuous signaling for sequence length indication, reducing overhead while maintaining resource efficiency
Solution Approach 2:
The UE autonomously selects between sequence lengths using locally configured parameters and channel occupancy detection, eliminating the need for network-side signaling to indicate sequence length changes. This self-service approach achieves dynamic resource efficiency without incurring additional signaling overhead
Data Source
AI summary
A user equipment (UE), or other network component can operate to configure different sets of resources for an uplink (UL) physical channel for an uplink (UL)-to-downlink (DL) channel occupancy time (COT) sharing to coexist with another radio access technology (RAT). An energy detection (ED) threshold can be selected from the different sets of resource configurations for an UL transmission based on one or more conditions. A gap can be configured between a physical random access control channel (PRACH) transmission and a PUSCH transmission based on one of at least a first value associated with a numerology between the PRACH and the PUSCH and a second value greater than the first value. The UL transmission can be provided based on the ED threshold or the configured conditional gap via the UL physical channel.