HARQ Multi-Link Scheduling for Wireless Reliability
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Solution Overview
Problem
Current wireless communication systems, particularly those using LTE, face challenges in achieving high reliability and low latency required for mission-critical applications due to limitations in existing HARQ mechanisms, which struggle with error rates and round trip times.
Innovation Solution
The implementation of hybrid automatic repeat/request (HARQ) with improved reliability for low latency wireless communications involves scheduling user equipment (UE) on multiple links, managing multi-modal capacity probability density functions per link and interference pattern, and using alternative acknowledgement formats to enhance rate-control loops, allowing for more efficient resource allocation and interference management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional HARQ mechanisms are used in LTE systems, then system compatibility and ease of operation are maintained, but reliability and latency performance are insufficient for mission-critical applications
Solution Approach 1:
The patent segments the HARQ process into multiple independent links between UE and eNB. Each link operates with its own HARQ instance, allowing parallel error correction attempts. This segmentation enables the system to achieve higher reliability by distributing error correction across multiple paths rather than relying on a single complex HARQ mechanism.
Solution Approach 2:
The patent introduces a new dimension to HARQ operation by enabling simultaneous HARQ processes across multiple radio links. Instead of improving reliability within a single link through increased complexity, the solution adds spatial diversity by utilizing multiple links, each with its own HARQ timeline and resources.
2Loss of time
If shorter transmission time intervals are implemented to reduce latency, then round trip time is reduced, but the reliability of HARQ communications deteriorates
Solution Approach 1:
The patent divides the communication path into multiple segmented links, each capable of independent HARQ operation. By segmenting the overall communication task across multiple links, the system can maintain shorter TTIs on each link while achieving cumulative reliability through the combined error correction capability of all links.
Solution Approach 2:
The patent establishes multiple HARQ links and their associated resources in advance, before actual data transmission begins. This preliminary configuration allows the system to immediately utilize multiple parallel paths when data needs to be transmitted, reducing the need for sequential error correction attempts and thereby reducing overall latency while maintaining reliability.
3Reliability
If multiple links are used for HARQ communications to improve reliability, then error rates decrease, but resource allocation complexity and interference management difficulty increase
Solution Approach 1:
The patent creates a universal HARQ framework that operates consistently across multiple links using the same protocol rules and procedures. Each link follows identical HARQ timing relationships and acknowledgment mechanisms, allowing the system to manage multiple links with standardized procedures rather than requiring complex link-specific configurations. This multi-functionality enables reliable multi-link operation while controlling complexity through standardization.
Data Source
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AI summary
Various aspects described herein relate to hybrid automatic repeat/request (HARQ) communications in a wireless network. A first instance of a HARQ communication is transmitted or received over a first set of one or more links. Based on the transmitting or receiving the first instance of the HARQ communication, a scheduling grant can be received for a second instance of the HARQ communication over a second set of one or more links different from the first set of one or more links. The second instance of the HARQ communication can accordingly be transmitted or received over the second set of one or more links based at least in part on the scheduling grant.