LTE Handover Control via QCI-Based Network Selection
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Solution Overview
Problem
Existing network selection techniques in LTE networks are inefficient when handling handovers, particularly for VoLTE and SR-VCC devices, as they often result in the loss or suspension of multiple bearers due to the inability of voice networks to support all Quality of Service (QoS) Class Indicators (QCIs).
Innovation Solution
The LTE network processes radio measurement data based on specific network-selection parameters, such as signal strength differences and hysteresis control timers, to select data communication networks instead of voice communication networks, thereby preserving multiple bearers with combined QCIs and ensuring continuity of services like voice, video, and gaming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the home LTE network drives the UE to the best available voice network, then voice call quality is improved, but multiple bearers are lost or suspended due to voice network inability to support all QCIs
Solution Approach 1:
The patent implements dynamic network selection by introducing a hysteresis timer that adapts the handover decision based on the duration of network conditions. The system dynamically adjusts between voice network and data network selection based on real-time QCI combination evaluation, allowing the network to switch strategies based on current bearer requirements and network conditions.
Solution Approach 2:
The patent changes the selection parameter from simple signal quality metrics to a composite parameter that includes the QCI combination state. By evaluating whether the QCI combination includes only voice-supported QCIs or includes data-only QCIs, the system adjusts the handover decision parameters to either prioritize voice quality or preserve bearer continuity.
2Speed
If traditional network selection techniques are used, then handover decisions are simple and fast, but bearer loss occurs due to inability to preserve all QCIs
Solution Approach 1:
The patent performs preliminary evaluation of the QCI combination before making the handover decision. By checking in advance whether the QCI combination includes data-only QCIs and setting the hysteresis timer accordingly, the system prepares the handover strategy beforehand, ensuring that bearer continuity is maintained without delaying the actual handover execution.
3Reliability
If the hysteresis timer is set to prolong connection to current network, then bearer loss is reduced, but handover responsiveness to network changes is delayed
Solution Approach 1:
The hysteresis timer value is dynamically adjusted based on the QCI combination state. When data-only QCIs are detected, the timer is set to a longer value to preserve bearers. When only voice-supported QCIs are present, the timer is set to a shorter value for faster handover response. This dynamic adjustment resolves the contradiction between reliability and time loss.
Data Source
AI summary
A Long Term Evolution (LTE) network wirelessly exchanges data with User Equipment (UE) over multiple data bearers having a combination of Quality-of-Service Class Indicators (QCIs). The LTE network wirelessly receives radio measurement data from the UE for a voice communication network and for a data communication network. The LTE network determines at network-selection parameters based on the combination of the QCIs for the UE. The LTE network processes the radio measurement data based on the network-selection parameters to select the data communication network for the UE instead of the voice communication network.