Packet Scheduling Mechanism for Buffer Delay Variation Compensation
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Solution Overview
Problem
Packet delay variation in communication networks, particularly due to buffer delay and head-of-line blocking, affects the timeliness and reliability of time-sensitive signals like IEEE1588/PTP in packet-switched networks, impacting real-time communication such as audio and video streaming.
Innovation Solution
A method that assigns the highest transmission priority to time-sensitive packets, queues them separately, and introduces a predetermined transmission delay to minimize buffer delay variations by interrupting or delaying non-time sensitive packets when necessary, ensuring time-sensitive packets are transmitted first, thereby reducing latency and packet loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If time-sensitive packets are assigned highest transmission priority and queued separately, then latency for time-sensitive traffic is reduced, but device complexity increases due to multiple buffers and scheduling mechanisms
Solution Approach 1:
The patent segments packet transmission by creating separate queues for time-sensitive and non-time-sensitive packets. The scheduling mechanism is divided into distinct handling paths: time-sensitive packets are transmitted immediately when available, while non-time-sensitive packets are transmitted only when time-sensitive queues are empty. This segmentation reduces latency for time-sensitive traffic without requiring complex integrated scheduling algorithms.
2Loss of time
If non-time sensitive packets are interrupted to transmit time-sensitive packets, then head-of-line blocking is reduced, but packet loss increases for non-time sensitive traffic
Solution Approach 1:
The patent segments the transmission medium into dedicated time slots for time-sensitive and non-time-sensitive packets. Time-sensitive packets occupy the transmission medium when available, and non-time-sensitive packets use the medium only when time-sensitive packets are absent. This temporal segmentation eliminates head-of-line blocking for time-sensitive packets while ensuring non-time-sensitive packets are not lost but merely delayed, maintaining their integrity.
3Productivity
If separate buffers are used for time-sensitive and non-time sensitive packets, then transmission priority is improved, but buffer memory requirements increase
Solution Approach 1:
The patent implements dynamic buffer allocation where the effective buffer memory requirement depends on traffic patterns. When time-sensitive traffic is present, its buffer is actively used and non-time-sensitive buffer is idle. When time-sensitive traffic is absent, the non-time-sensitive buffer is used. This dynamic sharing reduces total buffer memory requirements compared to static allocation while maintaining high transmission priority for time-sensitive packets.
Data Source
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AI summary
There is provided a method in a packet based network system for node-to-node transmission of data packets comprising timing packets and non-timing packets, which is directed to a mechanism for providing a delay variation compensation in a timing system or timing sensitive signal transport in a packet based network without participating in the timing signaling of the timing packets or timing sensitive packets themselves. The method comprises associating the data packets with different levels of transmission priority Pr, Pl, assigning highest (or highest available) transmission priority Pr to the timing packets, separately queuing the timing packets in different buffers 401, 402, and providing first opportunity transmission of the timing packets regardless of transmission priority level of non-timing packets waiting to be transmitted. The advantage of the method is that timing-sensitive traffic thereby experiences reduced buffer delay variations.