Activecasting Relay Station Handover in Multi-Hop BWA Systems
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Solution Overview
Problem
In multi-hop relay Broadband Wireless Access (BWA) systems, frequent Relay Station (RS) handovers lead to packet loss and service delays, and existing bicasting methods are not suitable for wireless networks, resulting in deteriorated system performance.
Innovation Solution
The implementation of an activecasting method, where a Base Station (BS) multicasts data packets to both the serving RS and the target RS using allocated resources, minimizing handover delays by considering channel conditions and utilizing redundant wireless resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If RS-to-RS handover is performed frequently to maintain mobility, then mobility support is improved, but packet loss and service delay increase
Solution Approach 1:
The system performs preliminary actions by buffering data packets at the Base Station before handover occurs. When handover is detected, the buffered packets are immediately transmitted to the target RS, eliminating waiting time and ensuring continuous service without packet loss or delay.
Solution Approach 2:
The Base Station acts as an intermediary that temporarily holds and manages data packets during the handover process. This mediator function allows seamless transfer of data from serving RS to target RS, maintaining service continuity and preventing packet loss during the transition.
2Reliability
If bicasting is used to avoid handover errors, then service continuity is improved, but device complexity increases due to multicasting requirements
Solution Approach 1:
The invention extracts and eliminates the complex multicasting mechanism from the system. Instead of using bicasting to achieve service continuity, the system uses a simpler unicast approach with data buffering at the Base Station, reducing device complexity while maintaining reliability.
Solution Approach 2:
The system uses temporary, disposable data buffering at the Base Station rather than implementing complex persistent multicasting infrastructure. This approach achieves service continuity with simpler, shorter-lived buffering operations instead of long-term multicasting capabilities.
3Productivity
If data packets are transmitted only to serving RS, then resource utilization is improved, but service continuity deteriorates during handover
Solution Approach 1:
The Base Station performs preliminary data buffering before handover occurs, preparing data packets in advance. This preliminary action ensures that when handover happens, data can be immediately forwarded to the target RS without interruption, maintaining both resource efficiency and service continuity.
Solution Approach 2:
The system dynamically adjusts data transmission based on handover status. During normal operation, data is transmitted only to the serving RS for optimal resource utilization. During handover, the system dynamically switches to buffer-and-forward mode, maintaining service continuity while adapting resource usage to current network conditions.
Data Source
AI summary
A technique for managing a packet to be transmitted to a Mobile Station (MS) that performs Relay Station (RS) handover in a multi-hop relay Broadband Wireless Access (BWA) system is provided. In the BWA system, a Base Station (BS) includes a controller for determining whether to perform activecasting on an MS upon receiving an activecast request message; a scheduler for allocating a resource by taking into consideration a channel condition between the MS and a serving RS when activecasting is determined to be performed; and a transmitter for multicasting a packet, which is to be transmitted to the MS, to a target RS and the serving RS by using the allocated resource.