Multi-Link Roaming Context Transfer for Sequence Number Continuity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless local area networks supporting multi-link operation, seamless roaming between access point multi-link devices within the same seamless mobility domain can result in data loss or duplication due to the lack of coordination of context information such as sequence numbers, buffer state, and media access control protocol data unit delivery progress, compromising network performance.
Innovation Solution
Implement mechanisms for coordinating sequence number (SN) state, buffer occupancy, and media access control protocol data unit delivery status between serving and target access point multi-link devices during roaming, including options for SN coordination, data flushing, and buffer state reporting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If seamless roaming is enabled between access point multi-link devices, then data transfer continuity is improved, but data loss or duplication occurs due to lack of context coordination
Solution Approach 1:
The serving access point performs preliminary actions by determining and transferring context information (sequence number state, buffer occupancy, MPDU delivery status) to the target access point before the roaming transition is complete. This advance preparation ensures that the target AP is ready to seamlessly take over data transfer without causing data loss or duplication, thus resolving the contradiction between maintaining continuity and ensuring reliability.
Solution Approach 2:
The serving access point acts as an intermediary by coordinating the context transfer between the client device and the target access point. It determines the appropriate context information to transfer and initiates the transfer to the target AP, ensuring proper coordination during the roaming process. This intermediary role prevents data loss or duplication while maintaining seamless data transfer continuity.
2Reliability
If context information is coordinated between serving and target access points, then data loss is avoided, but system complexity increases
Solution Approach 1:
The patent extracts only the essential context information needed for seamless roaming (sequence number state, buffer occupancy, MPDU delivery status) and transfers it from the serving AP to the target AP. By taking out only the critical elements rather than transferring all possible data, the solution achieves reliable data loss avoidance while minimizing the complexity of the coordination mechanism.
Solution Approach 2:
The context information is transformed into specific transferable parameters (sequence number state, buffer occupancy levels, delivery status flags) that can be efficiently exchanged between access points. This parameterization simplifies the coordination mechanism by converting complex context data into standardized, manageable parameters that are easier to process and transfer, thus reducing system complexity while maintaining reliability.
Data Source
AI summary
The present disclosure provides techniques for seamless roaming with uplink/downlink context transfer. A first AP MLD of a SMD establishes an association between the SMD and a non-AP MLD, maintains a DL transmit buffer comprising DL data MPDUs and corresponding sequence numbers for the DL data MPDUs, maintains a SN of a first unacknowledged DL data MPDU in the DL transmit buffer (WinStartO), receives a roaming request from the non-AP MLD, transfers DL context information to the second AP MLD, the DL context information comprising a SN of the first unacknowledged DL data MPDU (WinStartO) and a next SN value indicating a SN corresponding to a first DL data MPDU that the second AP MLD is expected to transmit to the non-AP MLD, and transmits a roaming response to the non-AP MLD.