Satellite-Based HARQ Feedback for Extended Propagation Delays
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Solution Overview
Problem
Existing wireless communication protocols, such as LTE, are designed assuming round-trip propagation delays of 3 milliseconds or less, which is not feasible for satellite-based communications due to orbital distances and delays exceeding this limit, leading to failures in HARQ operations.
Innovation Solution
Implement methods such as blind NACK, blind ACK, and TTI bundling to manage excessive propagation delays without modifying standard handsets, allowing HARQ to operate deterministically by proactively sending feedback or combining HARQ processes to reduce latency and improve efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard LTE HARQ protocol is used, then communication reliability is maintained under normal conditions, but HARQ operations fail when propagation delay exceeds 3 milliseconds
Solution Approach 1:
The patent changes the timing parameters of HARQ operations to accommodate satellite propagation delays. Specifically, it extends the round-trip time (RTT) window and adjusts the timing of retransmission attempts to match the longer delay characteristics of satellite communications while maintaining protocol compatibility with standard LTE handsets.
Solution Approach 2:
The patent introduces dynamic adaptation mechanisms that allow the HARQ process to adjust its behavior based on measured propagation delays. The system dynamically modifies retransmission timing and window sizes to optimize performance for the specific satellite link characteristics while maintaining compatibility with standard protocols.
2Reliability
If retransmission timing is extended to accommodate satellite delays, then communication reliability improves, but latency increases
Solution Approach 1:
The patent employs preliminary actions by pre-configuring extended timing windows and preparing retransmission resources in advance based on predicted satellite delay characteristics. This allows the system to accommodate long propagation delays without ad-hoc adjustments that would further increase latency.
Solution Approach 2:
The patent implements mechanisms to skip unnecessary waiting periods by using predictive timing based on satellite orbital mechanics. The system calculates expected delay ranges and prepares retransmissions at optimal times, reducing idle waiting while ensuring reliable delivery.
3Adaptability or versatility
If HARQ process timing is adjusted for satellite delays, then protocol compatibility is maintained, but standard design assumptions are violated
Solution Approach 1:
The patent achieves universality by designing a HARQ adaptation layer that can operate with both standard LTE handsets and satellite base stations. The adaptation mechanisms are implemented in the satellite equipment, allowing standard handsets to communicate with satellites without modification while maintaining protocol compliance at the interface level.
Data Source
AI summary
A method of communication over a cellular network connection between a mobile device and a base station is provided, wherein the mobile device and the base station are configured to operate according to a protocol, wherein the protocol has a design assumption of a maximum distance between communicating devices, and wherein the mobile device and the base station are separated by more than the maximum distance. The method might comprise receiving uplink data at the base station, decoding the uplink data, and prior to determining whether the uplinked data is correctly received at the base station, transmitting a feedback acknowledgement message to the mobile device, determining whether the uplinked data is correctly received at the base station, and if not, recording a need for retransmission, and transmitting to the mobile device a feedback message for a subsequent data unit, wherein the feedback message indicates failure of the uplink data unit.