Inter-Frequency Handover Control in Broadband Wireless Systems
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Solution Overview
Problem
Current broadband wireless access systems lack an effective method for inter-frequency handover within one cell and between different cells when multiple frequency allocations are used, particularly in IEEE802.16e systems, leading to inefficiencies in multimedia service provision due to unallocated frequency bands and unclear handover procedures.
Innovation Solution
A handover control method that involves a serving base station receiving a handover request from a mobile subscriber station, notifying a target base station, and performing a network reentry procedure based on supported frequency allocations, including steps for transmitting and confirming handover messages to ensure seamless frequency allocation and handover execution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple frequency allocations are allocated to one base station to increase subscriber accommodation and transmit data more efficiently, then the subscriber accommodation and data transmission efficiency are improved, but the handover control complexity increases because there is no established method for inter-frequency handover within one cell or between different cells
Solution Approach 1:
The target base station prepares frequency allocation information in advance by receiving a handover request notification from the serving base station and storing supportable frequency allocation details before the actual handover occurs. This preliminary preparation enables the handover to proceed smoothly without requiring complex real-time decisions during the handover execution.
Solution Approach 2:
The patent introduces a standardized handover control protocol that acts as an intermediary mechanism between the serving base station and target base station. This protocol includes defined message formats (handover request notification, handover request notification response) that mediate the handover process, reducing the complexity by providing clear procedural guidelines.
2Reliability
If a handover is performed from a serving base station to a handover target base station with multiple frequency allocations, then the service continuity is improved, but the handover execution time increases due to the need to determine which frequency allocation to use
Solution Approach 1:
The target base station performs preliminary action by receiving and processing the handover request notification message in advance, storing the supportable frequency allocation information before the handover execution. This eliminates the need for time-consuming frequency selection during the handover critical path.
Solution Approach 2:
The serving base station receives feedback from the target base station through the handover request notification response message, which includes information about supportable frequency allocations. This feedback mechanism enables the serving base station to make informed handover decisions and transmit accurate handover response messages, reducing overall handover time.
3Adaptability or versatility
If inter-frequency handover is attempted within one cell or between different cells without an established method, then the frequency band utilization is improved, but the handover reliability decreases due to lack of standardized procedures
Solution Approach 1:
The patent creates a universal handover control protocol that can handle multiple handover scenarios (within-cell handover, inter-cell handover, different frequency allocations) through a single standardized procedure. The handover request notification and response messages serve multiple functions: they convey subscriber information, indicate supported frequency allocations, and guide the handover execution regardless of the specific scenario.
Data Source
AI summary
A handover control method in a broadband wireless access system is disclosed. In a broadband wireless access system supporting multiple frequency allocations, in which a serving base station controls a handover, the present invention includes the steps of receiving from a mobile subscriber station a handover request message including an identifier of the mobile subscriber station, transmitting a handover request notification message including the identifier of the mobile subscriber station to a handover target base station, receiving a handover request notification response message including information for frequency allocation supportable by the target base station, and transmitting a handover response message including the information for the frequency allocation to the mobile subscriber station. Accordingly, in the broadband wireless access system supporting the multiple FA, the present invention enables the handover between FAs within one cell or between FAs in different cells.