Intermediate Buffer Management Layer for Link Handoff Packet Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current link layer handoff in wireless communication systems results in noticeable performance impacts, particularly for VoIP and PTT applications, due to packet loss and subsequent TCP congestion control mechanisms during inter-AR handoffs.
Innovation Solution
The introduction of an intermediate buffer management layer (IBML) between OSI layer 3 and lower layers, which buffers and transfers packets during a link layer hard handoff, reducing packet loss by enabling seamless handover of buffered data between source and target communications interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a new link layer connection is established between the MN and the target AR during inter-AR handoff, then the mobility agent function is successfully switched from source AR to target AR, but packet loss occurs and TCP congestion control is triggered
Solution Approach 1:
The source AR proactively transfers buffered data packets to the target AR before the handoff is completed. This preliminary action ensures that the target AR already has the necessary data when the handoff occurs, preventing packet loss without requiring TCP retransmission
Solution Approach 2:
The patent introduces an intermediate data transfer mechanism between the source AR and target AR. The source AR acts as an intermediary that holds and transfers buffered data to the target AR, ensuring continuous data flow during the handoff transition without gaps or losses
2Ease of operation
If the link layer flushes outstanding transmit and re-transmit queues during handoff, then the new link layer connection is established, but end-to-end application performance deteriorates
Solution Approach 1:
The patent maintains continuous data transmission during handoff by transferring buffered packets from source AR to target AR. This continuity prevents the interruption that would otherwise occur when flushing queues, ensuring that application performance remains unaffected by the handoff process
3Reliability
If TCP slow start procedure is invoked due to packet loss during handoff, then congestion control is initiated, but end-to-end throughput decreases
Solution Approach 1:
The patent applies preliminary anti-action by preventing packet loss at the link layer through proactive data transfer. This prevents the false congestion signal that would otherwise trigger TCP slow start, thereby maintaining high throughput while still providing accurate congestion control when actually needed
Data Source
AI summary
Various embodiments are described to address the need for an apparatus and method that improves link layer handoff by addressing the packet-loss problem existing today. An intermediate buffer management layer (IBML) (201, 211) is introduced below layer 3 of an OSI-based communications interface. The IBML buffers copies of OSI layer 3 packets being transmitted via lower layers (205, 215) of the interface and manages the buffer contents using indications the IBML receives from one or more of the lower layers. When the IBML receives an indication that a link layer hard handoff is proceeding, the IBML transfers the presently buffered packets to a corresponding IBML (202, 212) in the target communications interface. This sub-layer 3 buffer transfer enables the target communications interface to reduce packet-loss associated with the hard handoff.