Handover Control Using Packet Delay in Multi-Backhaul Networks
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Solution Overview
Problem
Current handover processes in networks with multiple backhaul connections, such as relay-enhanced access networks and femto cell environments, face inefficiencies due to increased end-to-end delay, which is particularly adverse for real-time and delay-sensitive bearers, and existing mechanisms are either cell-specific or inadequate for addressing UE-specific handover needs.
Innovation Solution
A method and apparatus for evaluating the suitability of an access node cell as a handover target based on expected packet delay and signal quality, enabling or disabling the cell for handover, and adjusting handover measurement reporting, using delay information, resource characteristics, and mobility information to ensure suitable handover decisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If handover processes are performed in networks with multiple backhaul connections (relay-enhanced access networks, femto cell environments), then network coverage and capacity are improved, but end-to-end delay increases which adversely affects real-time and delay-sensitive bearers
Solution Approach 1:
The patent applies preliminary action by performing handover preparation procedures in advance, including establishing X2 interfaces between donor base stations before handover is needed, and pre-configuring backhaul connections. This allows the network to quickly execute handovers without incurring significant delay during the actual handover moment, thus maintaining low end-to-end delay while enabling handover capability in relay-enhanced and femto cell networks
2Ease of operation
If existing handover mechanisms are used in networks with multiple backhaul connections, then handover functionality is provided, but the mechanisms are either cell-specific or inadequate for addressing UE-specific handover needs
Solution Approach 1:
The patent applies local quality by transitioning from cell-specific handover parameters to UE-specific handover parameters. Each user equipment can have customized handover thresholds, offset values, and measurement configurations tailored to its specific requirements and service type (e.g., delay-sensitive vs. non-delay-sensitive bearers). This allows different UEs in the same cell to have differentiated handover behaviors appropriate to their individual needs
3Area of stationary object
If relay nodes are introduced for coverage extension, then coverage area and cell capacity are enhanced, but the number of backhaul hops increases leading to higher packet delay
Solution Approach 1:
The patent introduces donor base stations as intermediaries that establish direct X2 interfaces with each other, creating a optimized backhaul path. Instead of multiple hops through relay nodes for handover signaling, the donor base stations communicate directly via pre-configured X2 interfaces. This intermediary approach reduces the number of hops and processing steps during handover, thereby reducing packet delay while maintaining the coverage extension benefit of relay nodes
Data Source
AI summary
There are provided measures for handover control for backhaul connections, said measures exemplarily including evaluation of the suitability of an access node cell in access network as target for a handover of a terminal based on delay information being indicative of an expected packet delay in a cell of the access node, wherein such delay information may be generated and/or exchanged in the access network. Said measures may exemplarily be applied for improving handover control in relay-enhanced access networks or networks that contain access nodes connected via different kinds of backhaul that can result in different end-to-end packet delays.