Mobile Relay Handover with Separated Data and Control Planes
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Solution Overview
Problem
In wireless communication systems like LTE and UMTS, mobile relay base stations deployed in areas such as city centers face challenges in efficiently handling handovers of user equipment (UEs) due to their low relative speed, which affects the quality of service and increases latency when transferring data and control traffic between mobile relay base stations.
Innovation Solution
A method is introduced where handovers are performed for data traffic only while maintaining direct control signalling links, allowing for the measurement of signal quality between relay stations and determining the need for handovers based on predetermined thresholds, enabling efficient data plane handovers without disrupting control plane operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If mobile relay base stations are deployed to provide wireless communication services in areas such as city centers, then service coverage and capacity are improved, but handover latency increases and quality of service deteriorates due to low relative speed between relay stations and user equipment
Solution Approach 1:
The patent segments the handover process into two independent parts: control plane handover and data plane handover. The control plane handover handles signaling and control messages, while the data plane handover handles user data traffic. This segmentation allows each plane to be optimized independently, reducing overall handover latency while maintaining service coverage.
Solution Approach 2:
The patent introduces a donor eNB as an intermediary entity that maintains control plane connectivity with the mobile relay base station. The donor eNB acts as a fixed anchor point, receiving control plane messages from the mobile relay and forwarding them to the core network, thereby stabilizing the control plane connection during mobile relay movements.
2Ease of operation
If conventional handover procedures are used for mobile relay base stations, then handover can be performed, but both data traffic and control signalling must be transferred, increasing handover complexity and latency
Solution Approach 1:
The handover procedure is divided into separate control plane handover and data plane handover operations. Control plane handover involves signaling between the mobile relay, donor eNB, and core network for mobility management. Data plane handover involves transferring user data paths. This segmentation simplifies the overall procedure by allowing independent optimization of each plane.
Solution Approach 2:
The control plane handover is performed preliminarily before data plane handover. The mobile relay establishes control plane connectivity with the donor eNB and receives handover commands in advance. This preliminary action prepares the system for the subsequent data plane handover, reducing overall handover latency and complexity.
3Reliability
If control signalling is transferred along with data traffic during handover, then complete handover is achieved, but handover latency increases and quality of service deteriorates
Solution Approach 1:
The patent segments handover into control plane handover (handling signaling and control messages) and data plane handover (handling user data traffic). The control plane handover is performed first to establish control connectivity, while data plane handover follows separately. This segmentation allows the control plane to be established quickly without waiting for data traffic transfer, reducing overall handover latency while maintaining completeness.
Solution Approach 2:
The control plane handover is executed preliminarily before data plane handover. The mobile relay establishes control plane connection with the donor eNB, receives handover commands, and prepares for data transfer in advance. This preliminary establishment of control connectivity reduces the time required for complete handover while ensuring reliability.
Data Source
AI summary
Providing mobility support of UEs that are served by mobile relay base stations, by providing handover of a UE for data traffic only between two mobile relay base stations. Exchanging information between the source and target mobile relay stations of the concerned UE in handover, and/or the corresponding donor base stations if applicable. The handover is triggered by any of the following: based on UE's measurement report, the signal quality of a neighbor cell is better than the current serving cell; based on the measurement of the serving mobile relay base station, the signal quality of the link to the UE is worse than a certain threshold; or based on the measurement of the serving mobile relay base station, the signal quality of a neighbor cell is much better than the current donor base station.