Selective HARQ Suppression for Low-Latency TCP Packet Flows
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing packet transmission methods using ACK/NACK and retransmission mechanisms on individual links introduce delays and resource consumption, particularly in low-latency packet flows, which can be detrimental to overall communication efficiency.
Innovation Solution
Implementing HARQ suppression techniques selectively for packet flows with low latency requirements, disabling ACK/NACK signaling and retransmissions on specific links, while relying on end-to-end packet retransmission mechanisms for reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ACK/NACK signaling and retransmission mechanisms are implemented on individual links, then communication reliability is improved, but latency and resource consumption increase
Solution Approach 1:
The patent extracts and removes the HARQ acknowledgment mechanism from the system for specific packet flows. By disabling HARQ ACK/NACK signaling at the physical and MAC layers for flows that support end-to-end retransmission (like TCP), the system eliminates the intermediate reliability mechanism that causes latency, while relying on the end-to-end TCP retransmission for reliability assurance.
Solution Approach 2:
Instead of using multiple intermediate ACK/NACK mechanisms across different layers (PHY, MAC, RLC) to ensure reliability, the patent inverts the approach by disabling these intermediate mechanisms and relying solely on the end-to-end TCP acknowledgment and retransmission mechanism. This inversion reduces complexity and latency while maintaining reliability through the higher-layer protocol.
2Reliability
If ACK/NACK signaling and retransmission mechanisms are implemented on individual links, then communication reliability is improved, but processing resources and bandwidth are consumed
Solution Approach 1:
The patent removes the HARQ acknowledgment processing from the system for specific packet flows. By disabling HARQ at the PHY and MAC layers for flows with end-to-end retransmission support, the system eliminates the processing overhead associated with generating, transmitting, and handling HARQ ACK/NACK signals, thereby reducing device complexity and freeing processing resources.
Solution Approach 2:
The patent applies a universal disabling of HARQ mechanisms across multiple packet flows that support end-to-end retransmission. Instead of implementing complex per-flow HARQ management, the system universally disables HARQ for all such flows, simplifying the processing requirements while relying on the universal TCP retransmission mechanism to handle reliability for all these flows collectively.
3Loss of time
If HARQ suppression is applied to packet flows, then latency is reduced, but reliability mechanisms must be ensured at higher layers
Solution Approach 1:
The patent introduces the TCP protocol as an intermediary reliability mechanism at the transport layer. By disabling HARQ at lower layers (PHY and MAC) and relying on TCP's end-to-end acknowledgment and retransmission mechanism, the system transfers the reliability function from the data link layer to the transport layer, thereby reducing latency while maintaining packet delivery reliability through this intermediary mechanism.
Data Source
AI summary
A first wireless communications device including a transmitter, such as a base station or UE, identifies a first traffic flow, e.g., a TCP packet flow, for which end to end packet retransmission is supported. The first wireless communications device transmits an explicit indication to a second wireless communications device to skip Hybrid Automatic Repeat Request (HARQ) feedback for data, corresponding to the first traffic flow, said data being transmitted to the second wireless communications device. The explicit indication to skip HARQ feedback for data is, e.g., one of: a HARQ Off Indicator in a Downlink Control Information (DCI) Scheduling message, a Semi-Persistent Scheduling HARQ Off Indicator, or a AUL HARQ Off Indicator. HARQ suppression is applied for the first traffic flow at a radio link layer and/or MAC layer.