Configurable HARQ Timing for Satellite Propagation Delays
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Solution Overview
Problem
Long Term Evolution (LTE) Hybrid Automatic Retransmission Request (HARQ) timing relationships are fixed and do not accommodate round-trip propagation delays greater than four milliseconds, which is a limitation for satellite communications and other deployments with large delays, leading to reduced throughput and reliability.
Innovation Solution
Determine configurable HARQ timing relationships and operational parameters based on round-trip propagation delay information, allowing for adjustable numbers of parallel stop-and-wait HARQ processes, which are signaled through System Information Blocks (SIBs), enabling HARQ to function effectively in deployments with large delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fixed HARQ timing relationship of 4 subframes is used, then LTE HARQ operation is simple and standardized, but it cannot accommodate deployments with round-trip propagation delays greater than four milliseconds
Solution Approach 1:
The patent makes the HARQ timing relationship dynamic by allowing it to be configured based on the actual round-trip propagation delay of the deployment scenario. Instead of a fixed 4-subframe timing, the system can adaptively set the timing relationship (k value) according to the propagation characteristics of satellite or terrestrial deployments, enabling HARQ to function effectively in both low-delay and high-delay environments
Solution Approach 2:
The patent changes the timing parameter (k value) of the HARQ process based on the propagation delay characteristics. By adjusting this parameter, the system accommodates different deployment scenarios - using k=4 for terrestrial deployments with small delays and larger k values for satellite deployments with delays exceeding 4 milliseconds, thus resolving the contradiction between fixed simplicity and adaptive versatility
2Productivity
If number of parallel HARQ processes is increased to support larger propagation delays, then continuous data transmission is maintained, but system complexity and resource overhead increase
Solution Approach 1:
The patent dynamically adjusts the number of parallel HARQ processes based on the configured timing relationship and propagation delay. Rather than using a fixed large number of processes, the system optimizes the count according to actual deployment needs - using fewer processes for terrestrial scenarios and increasing them for satellite scenarios where larger delays require more parallel processes to maintain continuous transmission
Solution Approach 2:
The patent changes the number of parallel HARQ processes as a configurable parameter based on the timing relationship. By adjusting this parameter alongside the timing configuration, the system achieves an optimal balance between maintaining continuous data transmission (productivity) and managing system complexity, avoiding unnecessary resource overhead in low-delay scenarios while providing sufficient parallelism in high-delay satellite deployments
Data Source
AI summary
Systems and methods for determining configurable timing relationships and operational parameters are provided. In some embodiments, a method of operation of a wireless device in a wireless system includes determining round-trip propagation delay information between the wireless device and a network node. This round-trip propagation delay information may be a round-trip propagation delay a quantized round-trip propagation delay, or any other value indicative of the round-trip propagation delay. The in method also includes determining a Hybrid Automatic Retransmission Request (HARQ) operational parameter based on the round-trip propagation delay information between the wireless device and the network node. In this way, HARQ is extended to work for deployments with large round-trip propagation delays, such as satellite systems. This may increase the throughput and reliability of data transmission.