Grant-Free Uplink Transmission Parameter Optimization
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Solution Overview
Problem
In the 5G NR Phase 1, the grant-free uplink transmission method in wireless communication systems faces inefficiencies due to excessive redundancy and air interface resource occupation, especially when the number of terminals is large, leading to reduced performance gains and increased signaling overhead.
Innovation Solution
A method where user equipment transmits a first radio signal in a first air interface resource pool, receives control information, and then transmits a second radio signal in a second air interface resource pool, with the base station acquiring beamforming and timing advance information to optimize grant-free data channel transmission, reducing the need for cyclic prefix and guard time, and dynamically adjusting transmission parameters to improve spectral efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If periodic reference signals are configured to acquire spatial characteristics for grant-free uplink transmission, then the base station can correctly receive uplink data, but excessive redundancy is added and air interface resources are excessively occupied
Solution Approach 1:
The base station performs spatial characteristic acquisition and timing advance adjustment in advance through random access procedures before grant-free transmission. The UE stores these pre-acquired parameters and uses them directly during grant-free transmission without requiring periodic reference signals, thus reducing resource occupation while maintaining reception accuracy.
Solution Approach 2:
The UE autonomously determines transmission parameters including spatial characteristics and timing advance based on pre-configured information and stored measurement results. The UE performs self-adjustment of transmission timing and beamforming parameters without continuous base station intervention or periodic reference signal transmission, reducing system overhead while maintaining reliability.
2Reliability
If enough Cyclic Prefix and Guard Time are added to each uplink transmitted data to avoid inter-slot interference, then interference between slots is avoided, but spectral efficiency is reduced
Solution Approach 1:
The base station performs timing advance adjustment in advance during random access procedures. The UE stores the timing advance value and applies it to grant-free transmissions to ensure uplink data from different UEs arrives at the base station at the correct time, avoiding inter-slot interference without requiring excessive guard time, thus maintaining spectral efficiency.
3Quantity of substance
If grant-free uplink transmission is used to reduce air interface signaling overhead, then signaling overhead is reduced, but transmission parameter accuracy deteriorates when the number of terminals is large
Solution Approach 1:
The system divides transmission parameters into two categories: frequently changing parameters (such as timing advance) that are adjusted through random access procedures, and relatively stable parameters (such as spatial characteristics) that are pre-configured and stored. This segmentation allows grant-free transmission to maintain accuracy for stable parameters while using minimal signaling for dynamic parameter adjustments.
Solution Approach 2:
The base station pre-configures spatial characteristics and other transmission parameters for multiple UEs during initial access. The UE stores these parameters and uses them for grant-free transmission, reducing the need for continuous signaling while maintaining parameter accuracy even when the number of terminals is large.
Data Source
AI summary
The disclosure discloses a method and device in user equipment and a base station for wireless communication. The user equipment transmits a first radio signal in a first air interface resource pool, then receives first control information, and transmits a second radio signal in a second air interface resource pool; the first control information is physical layer signaling, the second air interface resource pool is associated with the first air interface resource pool; the first control information comprises at least one of the first information and the second information; the timing advance of the second radio signal is related to the first information, a first transmission parameter set for transmitting the second radio signal is related to the second information; and the transmission of the second radio signal is grant-free.