Flowlet Scheduling for Wireless Packet Order

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Solution Overview

Problem

In wireless networks, particularly in fast-moving mobile systems like trains and buses, packet misorderings occur during handoffs due to dynamic network conditions and environmental RF challenges, leading to reduced throughput and latency issues, even with make-before-break roaming techniques.

Innovation Solution

A networking device identifies idle times between flowlets in a traffic flow and sends subsequent flowlets via a different wireless access point, ensuring packets are delivered in order by determining and utilizing the idle time to synchronize the transmission paths, and employing queuing and MAC adaptation to maintain packet order during handoffs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If make-before-break roaming is used to maintain connectivity during handoff, then connectivity continuity is improved, but packet misordering occurs

Engineering Contradiction:

Improveconnectivity continuityVSAvoidpacket order

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The traffic flow is segmented into flowlets separated by idle time thresholds. This segmentation allows the system to apply different access points to different flowlets, enabling controlled packet ordering while maintaining connectivity during handoff transitions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system determines idle time between flowlets in advance and uses this information to pre-plan which access point should handle subsequent flowlets. This preliminary analysis enables the system to maintain packet order without disrupting connectivity during handoff.

Inventive Principle:

Principle #10Preliminary action

2Stability of the object's composition

If packets are reordered at the mobile system to correct misordering, then packet order is improved, but latency increases due to extra reordering operations

Engineering Contradiction:

Improvepacket orderVSAvoidlatency

Core Design Contradiction:

Stability of the object's compositionVSLoss of time

Solution Approach 1:

Instead of reordering packets at the mobile system after reception, the invention inverts the approach by controlling packet transmission order at the access points. Packets are sent in the correct sequence from the beginning, eliminating the need for reordering operations at the mobile system and reducing latency.

Inventive Principle:

Principle #13The other way round (Inversion)

3Stability of the object's composition

If multiple access points are used for different flowlets, then packet misordering is reduced, but network complexity increases

Engineering Contradiction:

Improvepacket orderVSAvoidnetwork complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The system changes the parameter of access point selection based on flowlet idle time characteristics. By dynamically adjusting which access point handles which flowlet based on measured idle time parameters, the system maintains packet order without requiring complex multi-access point coordination infrastructure.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11575612B2Reducing packet misorderings in wireless networks

Publication Date: 2023.02.07 CISCO TECHNOLOGY INC

AI summary

In one embodiment, a networking device receives packets of a traffic flow destined for a mobile system. The networking device sends a first flowlet of the traffic flow towards the mobile system via a first wireless access point. The networking device determines an idle time between the first flowlet and a second flowlet of the traffic flow. The networking device sends, based on the idle time, the second flowlet towards the mobile system via a second wireless access point.