Sidelink HARQ Feedback Subcarrier Allocation
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Solution Overview
Problem
Current wireless communication systems, particularly in LTE and NR technologies, face challenges in efficiently transmitting sidelink hybrid automatic repeat request (HARQ) feedback due to limitations in subcarrier allocation and multiplexing techniques, which affect the reliability and efficiency of peer-to-peer communications between user equipment (UEs).
Innovation Solution
A method for determining and transmitting HARQ feedback in sidelink communications involves identifying sets of non-contiguous subcarriers for each sidelink communication, using these subcarriers to multiplex feedback, and employing pseudorandom noise (PN) sequences with orthogonal cover codes or cyclic shifts based on ACK/NACK decisions, ensuring efficient use of bandwidth and power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If contiguous subcarriers are used for HARQ feedback transmission, then the simplicity of resource allocation is improved, but the spectral efficiency and interference management deteriorate
Solution Approach 1:
The patent divides the frequency spectrum into non-contiguous subcarrier sets for different HARQ feedback transmissions. Each set of subcarriers is separated by a guard band, allowing multiple UEs to transmit feedback simultaneously without interference while maintaining organized resource allocation. This segmentation enables efficient spectral utilization by distributing feedback signals across different frequency regions.
Solution Approach 2:
The patent transitions from time-division multiplexing (contiguous subcarriers in different time slots) to frequency-division multiplexing with non-contiguous subcarrier sets. By introducing frequency separation with guard bands between subcarrier sets, the system achieves better interference management and spectral efficiency while maintaining resource allocation tractability through structured frequency domain organization.
2Quantity of substance
If more subcarriers are allocated for HARQ feedback, then the feedback capacity is improved, but the bandwidth consumption and power usage increase
Solution Approach 1:
The patent assigns specific non-contiguous subcarrier sets to different UEs or different HARQ feedback types based on their specific needs. Each UE receives feedback resources tailored to its channel conditions and feedback requirements, optimizing the local quality of resource allocation. This localized approach ensures that each UE uses an appropriate number of subcarriers for its feedback capacity needs without unnecessarily consuming excessive bandwidth or power.
Solution Approach 2:
The patent dynamically adjusts the number of subcarriers allocated to each UE's HARQ feedback based on channel conditions, feedback priority, and system load. By changing the parameter of subcarrier quantity adaptively rather than allocating fixed resources, the system optimizes the balance between feedback capacity and power consumption, allocating more subcarriers when needed and fewer when sufficient.
3Reliability
If non-contiguous subcarriers with guard bands are used, then the interference management is improved, but the resource allocation complexity increases
Solution Approach 1:
The patent segments the frequency spectrum into distinct non-contiguous subcarrier sets separated by guard bands. This segmentation provides natural frequency isolation between different HARQ feedback transmissions, improving interference management. The structured segmentation into predefined subcarrier sets maintains allocation complexity at manageable levels through systematic organization.
Solution Approach 2:
The patent creates a universal framework where non-contiguous subcarrier sets with guard bands serve multiple functions: providing frequency isolation for interference management, enabling simultaneous feedback from multiple UEs, and supporting different feedback types (ACK, NACK, DTX). This multi-functional approach reduces overall system complexity by using a single resource allocation mechanism for multiple purposes.
Data Source
AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment may determine hybrid automatic repeat request (HARQ) feedback for one or more sidelink communications received from one or more other UEs. The UE may identify one or more sets of subcarriers of a HARQ feedback occasion for the HARQ feedback for the one or more sidelink communications. The UE may transmit, to the one or more other UEs and on a sidelink, the HARQ feedback for the one or more sidelink communications using the one or more sets of subcarriers of the HARQ feedback occasion. Numerous other aspects are provided.