Hybrid Handoff for Wireless Base Stations
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Solution Overview
Problem
Current handoff techniques in wireless communication systems, such as hard and soft handoff, face challenges in balancing resource preservation, session interruption risk, throughput efficiency, and network complexity, particularly affecting real-time applications like voice communication.
Innovation Solution
A hybrid handoff scheme where control channel communications are transferred from a serving base station to a target base station while the mobile station continues data communication with the serving base station, using time periods designated for signaling and allocating a fast cell switch feedback channel for efficient handoff.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If soft handoff is used to maintain continuous communication and reduce session interruption, then reliability is improved, but device complexity and network complexity increase
Solution Approach 1:
The patent segments the handoff process into two independent phases: control channel handoff and traffic channel handoff. The control channel handoff is completed first, establishing signaling connectivity with the target base station. The traffic channel handoff follows separately, allowing data communications to be transferred. This segmentation reduces the complexity of simultaneous coordination required in traditional soft handoff while maintaining session continuity.
2Reliability
If soft handoff is used to provide diversity gain and reduce session interruption, then reliability is improved, but throughput efficiency decreases due to synchronous resource allocation requirements
Solution Approach 1:
By separating control channel handoff from traffic channel handoff, the patent eliminates the need for synchronous resource allocation across multiple base stations during the entire handoff process. The control channel phase handles signaling independently, while the traffic channel phase can proceed with more flexible resource allocation, thereby improving throughput efficiency while maintaining reliability.
3Device complexity
If hard handoff is used to preserve air-link resources and simplify network handling, then device complexity is reduced, but session interruption risk increases
Solution Approach 1:
The patent performs preliminary action by completing the control channel handoff before transferring the traffic channel. During the control channel handoff phase, the mobile station establishes signaling connectivity with the target base station in advance. This preliminary setup ensures that when the traffic channel handoff occurs, the target base station is already prepared to handle communications, reducing session interruption risk while keeping the overall process simpler than traditional soft handoff.
4Reliability
If soft handoff is used to reduce session interruption, then reliability is improved, but backhaul capacity requirements increase for high rate traffic channels
Solution Approach 1:
The patent segments the handoff process so that control channel communications are transferred first, establishing a clear path for signaling. This allows the traffic channel handoff to proceed with more efficient resource utilization and reduced backhaul overhead, as the control plane is already established at the target base station. The segmentation eliminates the need for prolonged dual-connectivity required in traditional soft handoff, reducing backhaul capacity requirements.
Data Source
AI summary
A system and method for handoff are provided. A mobile station performs a make-before-break handoff of a control channel between a serving and target base station and a break-before-make handoff of a traffic channel between the serving and target base stations. The traffic channel handoff is performed after the control channel handoff has completed.