Packet Scheduling With Deadline Adjustment for Low Jitter
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Solution Overview
Problem
In deterministic networks, latency jitter occurs due to varying node latencies, leading to failure in meeting service demands with stricter jitter requirements.
Innovation Solution
A method for packet scheduling that adjusts the time of packet transmission based on local deadline time, cumulative deadline time, and cumulative residence time to reduce latency jitter, using Deadline queues and deadline time adjustment values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If nodes send packets when their local deadline time is reached, then the minimum latency requirement is met, but the latency jitter becomes large and stricter jitter requirements are not met
Solution Approach 1:
The patent applies preliminary action by pre-calculating the cumulative deadline time and cumulative residence time before packet transmission. Each node along the deterministic path预先 computes these time parameters and includes them in the packet metadata, enabling downstream nodes to make informed scheduling decisions that proactively control latency jitter rather than reacting to it after it occurs.
Solution Approach 2:
The patent implements feedback by using the cumulative residence time (actual time spent at upstream nodes) to adjust the sending time at the current node. The deadline time adjustment value is calculated based on the difference between cumulative deadline time and cumulative residence time, creating a feedback loop that compensates for actual latency variations and maintains bounded jitter.
2Reliability
If a deterministic path is calculated with resource reservation, then QoS goals are achieved, but the system complexity increases due to centralized controller requirements
Solution Approach 1:
The patent applies self-service by enabling each network node to autonomously perform deadline time calculations and packet scheduling decisions using locally available information (cumulative deadline time and cumulative residence time from packet metadata). This eliminates the need for continuous centralized controller intervention, allowing nodes to self-manage their packet transmission timing while still achieving QoS guarantees.
Solution Approach 2:
The centralized controller performs preliminary action by pre-calculating the deterministic path and resource reservations, and pre-computing the cumulative deadline time for each node along the path. This preliminary configuration enables subsequent decentralized autonomous operation at individual nodes without requiring real-time centralized coordination.
3Ease of operation
If nodes transmit packets at their local deadline time, then transmission timing is simplified, but latency variations accumulate across nodes causing large jitter
Solution Approach 1:
The patent uses feedback to adjust the local deadline time based on actual cumulative residence time experienced by the packet at upstream nodes. The deadline time adjustment value = cumulative deadline time - cumulative residence time, creating a feedback mechanism that compensates for actual latency variations while maintaining simple local scheduling operations.
Solution Approach 2:
The patent changes the parameter of deadline time from a fixed local value to a dynamically adjusted value. The adjusted deadline time incorporates feedback about actual network conditions (cumulative residence time), allowing the system to adapt to latency variations while maintaining the simplicity of deadline-based scheduling at each node.
Data Source
AI summary
A method for packet scheduling, a network device, a storage medium, and a computer program product are disclosed. The method may include acquiring a local deadline time indicative of a maximum allowable residence time of a packet at a local node; acquiring a cumulative deadline time indicative of a sum of each local deadline time that the packet goes through at each upstream node via which the packet is transferred, and a cumulative residence time indicative of the sum of each local residence time that the packet goes through at each upstream node via which the packet is transferred; and calculating a deadline time adjustment value according to the local deadline time, the cumulative deadline time, and the cumulative residence time; and adjusting a time at which the packet is sent according to the deadline time adjustment value.