Wireless Handover in Drop State Using Previous Base Station Identifier

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Solution Overview

Problem

In wireless portable Internet systems, handovers often result in communication interruptions and data loss due to the sleep mode or handover process, particularly when a subscriber station moves between base stations, leading to a drop state where the target base station lacks necessary information for seamless re-entry.

Innovation Solution

A handover method where the mobile subscriber station determines a drop state and selects a target base station, including the previous base station's identifier in initial messages to facilitate re-entry, allowing the target base station to request handover and re-establish the network connection, thereby maintaining service continuity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the subscriber station moves between base stations in sleep mode, then mobility is achieved, but communication interruption and data loss occur

Engineering Contradiction:

ImprovemobilityVSAvoidservice continuity

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The invention performs preliminary actions by having the target base station request and receive handover information from the previous base station before the subscriber station completes its re-entry. The target base station proactively initiates the information transfer process using the previous base station identifier included in the initial ranging request, ensuring that service continuity can be maintained without waiting for the mobile station to provide all necessary information.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If conventional handover methods are used, then base station switching is achieved, but handover delays and data loss occur in drop states

Engineering Contradiction:

Improvebase station switchingVSAvoidhandover delay

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The invention uses the previous base station identifier as an intermediary key that enables the target base station to identify and contact the previous base station. This identifier acts as a mediator that facilitates the transfer of handover information between base stations without requiring the mobile station to maintain continuous communication links, thereby reducing handover delays.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The target base station proactively requests handover information from the previous base station before the mobile station completes its re-entry process. This preliminary action eliminates the need to wait for the mobile station to provide all handover information, significantly reducing handover delay time.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If the target base station lacks handover information, then re-entry is simplified, but service session continuity is interrupted

Engineering Contradiction:

Improvere-entry processVSAvoidservice session information

Core Design Contradiction:

Ease of operationVSLoss of information

Solution Approach 1:

The previous base station identifier serves as an intermediary that enables the target base station to obtain necessary service session information from the previous base station. The identifier allows the target base station to act as a mediator in the information transfer process, receiving handover information including service session data from the previous base station to maintain continuity.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Reliability

If radio resources are extensively used for handover information transfer, then service continuity is maintained, but radio resource efficiency decreases

Engineering Contradiction:

Improveservice continuityVSAvoidradio resource consumption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The invention extracts only the essential previous base station identifier from the handover information that needs to be transferred. By taking out just this critical piece of information that enables the target base station to contact the previous base station, the system minimizes radio resource consumption while still achieving service continuity through subsequent information transfer.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS8934448B2Handover method in wireless portable internet system

Publication Date: 2015.01.13 SAMSUNG ELECTRONICS CO LTD

AI summary

Disclosed is a handover method in a wireless portable Internet system. When a mobile subscriber station is in a drop state, a ranging request message including an identifier of a previous base station and a string generated by encoding the ranging request message using an authentication key of the previous base station is sent to a target base station. The target base station requests the previous base station to execute handover of the mobile subscriber station using the identifier of the previous base station included in the ranging request message. The previous base station carries out message authentication using the encoded string received from the target base station, and when the authentication is successful, transmits information about the mobile subscriber station that is required for handover to the target base station. Accordingly, a ceaseless service session can be provided even in the drop state.