Wireless Handover via Base Station Resource Reservation
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Solution Overview
Problem
In wireless mobile communication systems, especially in 4G systems like IEEE 802.16e, handovers between Base Stations (BS) are inefficient due to the need for scanning across multiple frequency bands and modes, leading to increased scanning time and hardware/software complexity, and the inability to receive data traffic during scanning.
Innovation Solution
The system and method enable efficient scanning and handover by allowing Mobile Stations (MS) to scan in a predetermined frequency band or mode, with Base Stations reserving radio resources in advance to ensure successful handovers and minimize delay, using modified messages like MOB_NBR-ADV and RESOURCE-RESERVE-REQ to manage resource allocation between BSs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the MS scans across multiple frequency bands and modes to find the best BS, then the handover reliability is improved, but the scanning time and device complexity increase
Solution Approach 1:
The serving BS proactively reserves radio resources at the target neighbor BS before the MS actually needs to hand over. This preliminary resource reservation eliminates the need for the MS to scan multiple frequency bands and modes during handover, as the target BS is already prepared to receive the MS. The resource reservation message is sent in advance, and the MS can directly transition to the predetermined frequency band or mode where resources are already allocated.
Solution Approach 2:
The serving BS acts as an intermediary that coordinates between the MS and the target neighbor BS. It sends resource reservation requests to the target BS based on MS measurements, and then provides the MS with information about the reserved resources. This intermediary role eliminates the need for the MS to perform extensive scanning, as the serving BS has already established the handover path and resource allocation.
2Reliability
If the MS scans across multiple frequency bands and modes, then the handover reliability is improved, but the hardware and software complexity increase
Solution Approach 1:
The target BS reserves radio resources in advance before the MS needs to hand over. This preliminary action means the MS does not need complex hardware or software to scan and evaluate multiple frequency bands and modes during handover. The MS simply follows the predetermined path provided by the serving BS, significantly reducing its scanning complexity.
Solution Approach 2:
The serving BS serves as an intermediary that handles the complexity of coordinating with multiple neighbor BSs and managing resource reservations. The MS only needs to provide measurement information and follow the handover instructions from the serving BS, rather than independently managing complex scanning across multiple frequency bands and modes.
3Measurement precision
If the MS performs scanning to measure CINRs of pilot signals, then the handover accuracy is improved, but the data reception is interrupted
Solution Approach 1:
Radio resources are reserved at the target BS before the MS needs to hand over. This allows the MS to maintain data reception on the current link while the handover is prepared in advance. The MS can continue receiving data until the handover is triggered, at which point it switches to the predetermined frequency band or mode where resources are already allocated, minimizing interruption.
Solution Approach 2:
The system maintains continuous data reception by preparing the handover path in advance. The MS continues to receive data from the serving BS until the handover is executed, at which point it transitions to the target BS that has already reserved resources. This eliminates gaps in data reception that would occur during traditional scanning-based handovers.
Data Source
AI summary
A system and method for performing handover in a wireless mobile communication system are provided. In a Mobile Station (MS)-initiated scanning method of an (MS) in a wireless mobile communication system having at least two frequency bands with different central frequencies, the MS receives from a serving Base Station (BS) a mobile neighbor advertisement message including information about available radio resources of the neighbor BSs, transmits a new scanning request message to the serving BS, if the MS determines to measure Carrier-to-Interference and Noise Ratios (CINRs) of pilot signals from the serving BS and the neighbor BS, receives from the serving BS a response message for the scanning request message, including information about a BS which has reserved radio resources for a predetermined one of the at least two frequency bands, and measures the CINRs of the pilot signals in the predetermined frequency band.