Grant-Free Uplink Transmission Using Interleaving and CDMA
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In next-generation wireless communications networks, the grant-free transmission mode experiences reliability issues and increased latency due to contention-caused collisions during massive user access, particularly in scenarios requiring ultra-reliable and low-latency services.
Innovation Solution
A grant-free transmission method that pre-allocates transmission resources to terminal devices, allowing them to select and use resources without dynamic scheduling by the network, using interleaving patterns and Code Division Multiple Access (CDMA) coding schemes to improve reliability and distinguish between devices, thereby reducing collisions and enhancing link performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If grant-free transmission is used for massive user access, then transmission latency is reduced and access efficiency is improved, but transmission reliability deteriorates due to contention-caused collisions
Solution Approach 1:
The patent segments the code domain by assigning different codebooks to different UEs. Each UE is configured with a specific codebook from a codebook set, and uses codes from that codebook for grant-free transmission. This segmentation in the code domain reduces collision probability while maintaining the low-latency benefits of grant-free access.
Solution Approach 2:
The patent applies local quality by making the codebook configuration UE-specific. Each UE receives tailored codebook configuration parameters (such as codebook index, spreading factor, root index) from the network, allowing local optimization of transmission characteristics for each UE while maintaining overall system efficiency.
2Productivity
If multiple UEs transmit on the same time-frequency resource in grant-free mode, then resource utilization is improved and access overhead is reduced, but collision probability increases reducing transmission reliability
Solution Approach 1:
The patent introduces a new dimension for resource differentiation by moving from traditional time-frequency resource allocation to code-domain resource allocation. By assigning different codebooks and codes in the code domain, multiple UEs can simultaneously transmit on the same time-frequency resources with reduced collision probability, effectively adding a fourth dimension to resource allocation.
Solution Approach 2:
The patent changes the parameter space for resource allocation by using codebook configuration parameters (codebook index, spreading factor, root index, cyclic shift) instead of traditional time-frequency resource parameters. This parameter transformation allows for more granular and flexible resource differentiation, enabling better collision avoidance while maintaining high resource utilization.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Embodiments of this application provide a grant-free transmission method, a terminal device, and a network device, to improve grant-free transmission reliability. The grant-free transmission method includes: obtaining, by a terminal device, an interleaving pattern based on at least one of a cell identity of the terminal device, a terminal device identifier, time-domain resource information, and frequency-domain resource information; interleaving data based on the obtained interleaving pattern, to obtain interleaved data; and sending the interleaved data.