Configured Grant Uplink Transmission in NR-U
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Solution Overview
Problem
In next-generation wireless communication systems, maintaining fair coexistence with incumbent technologies in unlicensed spectrum, particularly in the 5 GHz band, is challenging due to quadruple contention issues during uplink transmissions, which can degrade performance and increase latency.
Innovation Solution
Configured grant uplink transmission in New Radio (NR) systems allows User Equipment (UE) to transmit immediately after successful Listen Before Talk (LBT), avoiding multiple contention steps and not relying on an UL grant, thereby coexisting with Wi-Fi and reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional scheduled uplink transmission is used, then reliable connection is maintained, but latency increases due to multiple contention steps and UL grant dependencies
Solution Approach 1:
The network performs preliminary actions by configuring grant parameters (time resources, frequency resources, modulation and coding scheme) in advance through RRC signaling before the actual transmission occurs. This eliminates the need for real-time UL grants and multiple contention steps, allowing the UE to transmit immediately after LBT while maintaining connection reliability through pre-established configuration.
2Reliability
If multiple contention steps are performed for uplink transmission, then channel access is controlled, but performance degrades due to increased contention delays
Solution Approach 1:
The invention extracts and eliminates the UL grant step from the traditional four-step contention process. By removing this intermediate step through configured grant mechanism, the transmission process is reduced to only essential LBT and transmission steps, thereby reducing contention delays while maintaining fair channel access control through network-configured parameters.
Solution Approach 2:
Network performs preliminary configuration of grant parameters (time resources, frequency resources, modulation and coding scheme) through RRC signaling before transmission. This pre-establishes all necessary transmission parameters, eliminating the need for real-time UL grants and reducing contention steps while maintaining controlled channel access.
3Loss of time
If configured grant uplink transmission is used, then latency is reduced and coexistence with Wi-Fi is improved, but device complexity increases due to additional configuration requirements
Solution Approach 1:
The configured grant mechanism serves multiple functions simultaneously: it enables low-latency transmission, facilitates Wi-Fi coexistence through LBT-based access, provides fair spectrum sharing, and maintains connection reliability. By consolidating these functions into a single unified mechanism with pre-configured parameters, the solution achieves multiple benefits without proportionally increasing device complexity.
Data Source
AI summary
Technology for a user equipment (UE) operable for configured grant uplink (UL) transmission in new radio unlicensed (NR-U) is disclosed. The apparatus can comprise one or more processors. The one or more processors can be configured to select, at the UE, a hybrid automatic repeat request process identifier (HARQ process ID) from a set of HARQ IDs. The one or more processors can be configured to insert the HARQ process ID into uplink control information (UCI) on a physical uplink shared channel (PUSCH). The one or more processors can be configured to encode, at the UE, the UCI for transmission to a next generation node B (gNB) via a configured grant uplink transmission using the HARQ process ID.