Inter-system Call Handover Using Preliminary Neighbor Cell Measurements
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Solution Overview
Problem
Current mobile communication devices face challenges in seamlessly handover calls between networks with different air interfaces, leading to substantial delay and potential packet loss, especially when high-quality data calls are involved, due to the need for dual transceivers which increase cost, size, and weight.
Innovation Solution
A method for call handover between networks with dissimilar air interfaces, where a mobile communication device performs neighbor cell measurements, transmits session profiles, and negotiates with a radio network controller to switch to a target base station on a different network, using a grant message with connection parameters to minimize interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a mobile communication device uses dual transceivers to support multiple air interfaces simultaneously, then handover capability between different networks is improved, but device cost, size, and weight increase substantially
Solution Approach 1:
The system performs preliminary measurements of neighbor cells on the target air interface before actual handover occurs. The mobile device tunes to the target frequency temporarily to measure signal quality and transmit uplink signals, allowing the network to evaluate handover feasibility in advance without committing to immediate handover, thus avoiding the need for continuous dual transceiver operation
Solution Approach 2:
The network controller acts as an intermediary that coordinates the handover process between the mobile device and target base station. The controller manages the measurement configuration, receives measurement results, makes handover decisions, and coordinates resource allocation, allowing the mobile device to use a single transceiver while the network handles the complexity of multi-interface coordination
2Adaptability or versatility
If the mobile communication device performs measurements on neighbor cells of a different air interface, then handover preparation is improved, but call interruption time increases due to tuning away from the serving base station
Solution Approach 1:
The mobile device performs measurements on the target air interface periodically or at scheduled intervals rather than continuously. The network configures specific measurement windows where the device temporarily tunes to the target frequency to perform measurements and transmit signals, then returns to the serving cell for data transmission, minimizing disruption to the ongoing call
Solution Approach 2:
Measurements and signal transmissions on the target air interface are performed in advance before the actual handover decision is made. This preliminary action allows the network to assess handover conditions without requiring the device to remain away from the serving cell for extended periods, reducing call interruption time
Data Source
AI summary
A call in progress in a first communication network is handed over to a second communication network which uses a different air interface. To facilitate the handover, the present serving base station commands the mobile communication device to take measurements of surrounding cells of the second communication network. The measurements are sent along with a handover request from the serving base station to a radio network controller of the second network, which decides upon a cell to which the cal will be handed. A grant message including an identifier to be used by the mobile communication device and an identifier of the base station receiving the handover is transmitted back to the first network, and used by the mobile communication device in handing over the call.