Pre-DFT Spreading Codes for Uplink Control Information Multiplexing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wireless communication systems face inefficiencies in resource utilization due to the need to repeat modulated communications across multiple symbols when using cover codes across multiple symbols, leading to suboptimal use of shared time-frequency resources for uplink control information (UCI) in multiple-user scenarios.
Innovation Solution
The implementation of pre-discrete Fourier transform (DFT) time-domain spreading codes for user equipment (UE) multiplexing, utilizing orthogonal cover codes (OCCs) such as Fourier basis or Hadamard matrix-based codes to enable efficient multiplexing of UCI across multiple UEs within the same time-frequency resources, ensuring orthogonality and reducing the need for repeated transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If modulated communications are multiplied by a cover code across multiple symbols, then user multiplexing is enabled, but resource utilization becomes inefficient due to the inability to divide the minimum frequency resource unit among multiple UEs
Solution Approach 1:
The patent segments the minimum frequency resource unit (resource block) into smaller subcarriers that can be individually assigned to multiple UEs. Instead of treating the entire resource block as an indivisible unit, the system divides it into 12 subcarriers, allowing flexible allocation to support user multiplexing while maintaining efficient resource utilization.
Solution Approach 2:
The patent applies different cover codes to different UEs based on their specific resource allocations. Each UE receives a customized cover code assignment that matches its allocated subcarriers and symbols, enabling orthogonal separation of multiple users while optimizing resource usage for each individual user's transmission needs.
2Reliability
If modulated communications are repeated across multiple symbols, then coverage is improved, but resource utilization deteriorates due to redundant transmissions
Solution Approach 1:
The patent applies cover codes to modulated communications before DFT spreading and resource mapping. This preliminary encoding ensures that multiple UEs can transmit simultaneously on the same time-frequency resources with orthogonal separation, eliminating the need for redundant retransmissions while maintaining coverage through the inherent orthogonality of the cover codes.
3Device complexity
If the minimum frequency resource unit is used as-is, then resource allocation is simple, but user multiplexing becomes difficult due to the inability to easily divide the resource unit
Solution Approach 1:
The patent divides the resource block into 12 subcarriers and allows flexible assignment of these subcarriers to multiple UEs. This segmentation enables the system to support user multiplexing by allocating different subsets of subcarriers to different users, while the standardized subdivision pattern keeps the allocation process manageable and not overly complex.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Methods, systems, and devices for wireless communications are described. Pre-discrete Fourier transform (DFT) time-domain spreading codes may be applied for UE multiplexing for uplink control information (e.g., over shared resources of an uplink slot). For example, a moderate number of UEs may be multiplexed within the same slot by having each UE spread modulation symbols before DFT-spreading by different spreading code. For orthogonality across UEs, the pre-DFT spreading codes may be selected as orthogonal cover codes (OCCs). The spreading sequences can be generated from a set of any orthogonal sequences or generated from unitary matrices. In some cases, orthogonality in the time domain may be kept as well as a frequency division multiplexed (FDM) structure in the frequency domain. For such property, a Fourier basis OCC design may be used. In some other examples, a Hadamard matrix based OCC design may be used.