KR20050020878A - Method for implementation of handover between wireless lan and cellular networks - Google Patents

Abstract

PURPOSE: A handover method between a wireless LAN and a wireless public network is provided to ensure the stability and reliability for monitoring a remote patient which requires successive data transmission. CONSTITUTION: A PDA(Personal Digital Assistant) measures the strength of a signal received from an AP(Access Point)(S101) and checks whether the measured signal strength is greater than a pre-set reference value for discriminating a wireless LAN environment and a wireless public network(S102). If the measured signal strength is greater than the pre-set reference value, the PDA checks a currently connected communication network(S103) to determine whether the currently connected communication network is being connected with a remote server through an RAS(Remote Access Server) of the wireless public network(S104). If the PDA determines that the currently connected communication network is providing a bio-signal measured from a testee to the remote server, it cuts off the connection with the wireless public network and is simultaneously connected with the wireless LAN(S105,S106). The PDA transmits the bio-signal data with respect to the testee to the remote server through the wireless LAN so that the testee can be monitored from the remote place(S107).

Description

Handover method between wireless LAN and wireless public network {METHOD FOR IMPLEMENTATION OF HANDOVER BETWEEN WIRELESS LAN AND CELLULAR NETWORKS}

The present invention relates to a wireless communication network, and more particularly, data detected when a data source continuously generating low-speed data, such as a patient monitoring system, moves between an indoor wireless LAN environment and an outdoor wireless public network environment. The present invention relates to a handover method between a wireless LAN network and a wireless public network for transmitting the data stably to a monitoring system.

In general, the proliferation of infrastructure and improvement of service quality for wireless public network enables users to continuously transmit and receive data in various environments using PCS, IMT-2000 terminal, and portable information terminal that they carry. I'm giving it.

In addition, as the demand for consumers to receive multimedia services anytime, anywhere has increased, wireless infrastructure has been rapidly increasing due to the advantages of near-free call charges and wide bandwidth as indoor wireless LANs have been established in indoor environments. The use of this is increasing.

In particular, the use of IEEE 802.11b wireless LAN devices using the 2.4GHz band that can be easily wirelessly connected to the existing wired infrastructure is rapidly increasing.

Despite the rapid growth of wireless LANs, wireless LANs are still mainly used in indoor environments such as homes, offices, and public institutions, and general services in outdoor environments are inadequate.

Therefore, in the process of performing data communication using a portable information terminal (hereinafter, referred to as a 'PDA') equipped with a wireless LAN card capable of jointly connecting the wireless public network and the wireless LAN, the environment and the wireless public network When moving a LAN environment, data communication is disconnected due to differences in applications and protocols supported in respective communication environments.

For example, when performing data communication in a wireless LAN environment, if a user moves out of another area not covered by the wireless LAN environment, data transmission may be interrupted.

Therefore, the disconnection of the transmission data in the monitoring of a remote patient where continuous data transmission is required causes a problem that the monitoring of the patient cannot be normally performed.

The present invention has been invented to solve the above problems, its purpose is to measure the signal strength from the AP (Access Point) of the wireless LAN as the user moves out of the service area of the wireless LAN environment In this case, automatic switching to the wireless public network is performed, and when entering the wireless LAN environment from the wireless public network environment, the stable broadband high-speed communication is switched to the service of the wireless LAN accompanied by stable broadband high-speed communication. It enables continuous transmission to provide stability and reliability in remote patient monitoring where continuous data transmission is required.

The present invention for realizing the above object in the data transmission using the portable information terminal, the communication module of the portable information terminal measuring the signal strength from the AP and comparing with the set reference value; Determining a connected communication environment in which current data transmission is maintained; And handing over the communication network according to the signal strength compared to the reference value and the currently connected communication environment to continue data transmission to the remote server.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram illustrating a wireless data environment to which the present invention is applied.

As can be seen from the figure, the PDA 100 as a medium for transmitting and receiving wireless data is applied.

As can be seen in FIG. 2, the PDA 100 includes a biosignal measurement module 110, a PDA module 120, and a wireless communication module 130.

The biosignal measuring module 110 is a module for detecting a data source, and extends contraction of the heart muscle from a predetermined number of ceramics (hereinafter referred to as an electrode terminal) attached to the left and right wrists and ankles or ribs of the examinee. Detects and analyzes waveforms such as P, Q, R, S, and T, which are active currents generated according to the cardiovascular system, and measures diseases of the heart system such as angina, myocardial infarction, and arrhythmia.

The PDA module 120 is a module that performs various operations for various voice communication and data communication in the portable information terminal. The PDA module 120 displays information on the presence or absence of heart abnormality and cardiac disease of the subject to be measured through display means.

The wireless communication module 130 transmits a monitoring device installed in an affiliated medical institution or a hospital in charge of periodic inspection by processing a data source for a cardiac abnormality and a cardiac disease of a test subject measured and analyzed by connecting to a wireless communication network. do.

The wireless communication module 130 is composed of a cellular communication module and a wireless LAN card for connecting a wireless public network.

The wireless data environment of the PDA 100 forms an indoor environment 200 and an outdoor environment 300.

Indoor environment 200 is made of a connection between the wireless LAN and the AP 210, by connecting the wireless LAN network 400 through the relay of the AP 210 and stable and high speed with the server 600 does not exist in the same network state Broadband data communication is performed.

In addition, the outdoor environment 300 is formed by the connection of the base station 310 relaying the connection of the wireless public network through the cellular protocol, and the server 600 through the wireless public network network 500 connected to the base station 310. In connection, data communication is performed.

Therefore, the indoor environment 200 transmits the data source to the remote monitoring means via the wireless LAN network 400, and the outdoor environment 300 transmits the data source to the remote monitoring means through the wireless public network 500. do.

In the above, the transmission data source of the PDA 100 should be able to be transmitted to a remote place anytime and anywhere, and applies a biosignal of an examinee requiring continuous observation from a remote place.

Accordingly, the PDA 100 is connected to the measurement module 110 for measuring the biological signal of the subject through a serial interface, the measurement module 110 is a conductor (hereinafter, referred to as 'electrode' attached to each part of the subject's body). The terminal detects and analyzes information such as ECG, respiration, and body temperature of the examinee and transmits the information to the PDA 100 through the serial interface, and the PDA 100 measures the measurement module 110. Field inspection is performed on the test subject's biometric information detected from the tester. If the error is not detected in the received data as a result of the test, and reliability is confirmed, it is displayed on its own display means and measured by the test subject according to the current communication environment. Monitor the vital signs of the subject by transmitting the data source to a remote means, that is, monitoring means installed in medical institutions such as homes, hospitals and emergency centers. This makes it possible.

As shown in FIG. 3, the wireless LAN network constructed in the indoor environment 200 includes remote monitoring means for monitoring the test subject A and the test subject A, which are data sources, in the same network environment. By applying the relatively fast Ad-Hoc method, the biosignal data measured from the monitor A is transmitted to the monitoring means without the relay procedure of the central management means.

That is, as shown in the figure, when the remote monitoring means is a PC (100A) (100B) existing on the same network, the PDA (100) from the monitor (A) in the Ad-Hoc method without the relay procedure of the central management means The measured biosignal data is transmitted.

However, when the PDA 100 and the remote monitoring means for detecting a data source from the monitored person A do not exist on the same network, communication with the remote monitoring means existing on another WLAN network by applying an infrastructure scheme. This is done by the following structure.

An AP (Access Point; 210) connected to the PDA 100 carried by the examinee A through a wireless LAN to relay data transmission and reception, and AC for managing and controlling the data transmission / reception relay of the AP 210. Access Controller (220), RT (Router; 230) for relaying communication data by connecting a plurality of communication networks connected to the AC 220 and connected to the wireless Internet network, and manages the wireless LAN Internet network 400 WIMS (Wireless Internet Management System; 410), the wireless LAN Internet network 400 and the remote home, hospital, emergency center operating under the management of the WIMS (410) is installed, the wireless LAN Internet network 400 It comprises a server 600 connected to and receiving the data transmitted from the PDA 100 to monitor the biological signal of the subject (A).

Accordingly, the PDA 100 carried by the examinee A accesses the AP 210 through the wireless LAN, and then connects the RT 230 to another wireless LAN internet network 400 so that the home, hospital, and emergency of the remote place can be accessed. Monitoring of the subject A is performed by transmitting data on the measured bio-signals to the server 600 installed in the center or the like.

In addition, the infrastructure for the outdoor environment 300 in the above, as can be seen in the accompanying Figure 4, the wireless communication of the bio-signal data measured by being connected through the wireless public network with the PDA (100) carried by the examinee (A) BS (Base Station: 310) for relaying transmission and reception, BTS (Base Transfer System: 320) in charge of processing bio-signal radio data relayed through BS 310, MSC (Mobile Switching Center: 340) and BTS Base Station Controller (330) for controlling and managing a plurality of BSs 310 located between the 320 and a Public Switched Telephone Network (PSTN) 350 for connecting the MSC 340 to a subscriber wired terminal. And a RAS (Remote Access Server) 360 connected to the BSC 330 to perform remote control so that TCP / IP-based data communication can be performed, and the RAS 360 Packet network 370 for transmitting packet data connected to PSDN (Public Switched Data Network: 380) connecting the packet network 370 and the Internet network 390 to connect a server installed in a remote home, hospital, emergency center, and the like to transmit the biosignal data measured by the monitored person A. )

The communication path connection between the PDA 10 carried by the testee A and the RAS 360 is maintained in the point to point (PPP) connection, and the TCP / remote server is installed from the RAS 360 to a server installed remotely. Connected by IP protocol.

As described above, in transmitting data on a biological signal, which is a data source measured from the monitor A, to the monitoring means located at a remote location, the monitor A is over the indoor environment 200 and the outdoor environment 300. Since the case of lapping occurs, appropriate switching must be involved.

Therefore, a process of implementing an overlap according to entry into different communication environments will be described with reference to FIG. 5.

First of all, in the two communication environments of the wireless public network and the wireless LAN in data transmission, priority is given to a WLAN in which cost reduction, fast transmission speed, and communication stability are maintained.

The measurement module connected to the PDA 100 via a serial interface measures biosignal, such as ECG, body temperature, and breathing information for the subject A, from an electrode terminal attached to a predetermined measurement portion of the subject A. Then, after analyzing the result and applying the result to the PDA 100, the PDA 100 to the subject (A) detected by the monitoring means installed in a remote place, for example, a server installed in a home, hospital, emergency center, etc. Transmit a biological signal

At this time, the PDA 100 measures the signal strength from the AP 210 (S101), and determines whether the measured signal strength is greater than or equal to a reference value set for distinguishing the environment of the wireless LAN environment from the wireless public network (S102).

When it is determined that the signal strength measured from the AP 210 is equal to or greater than the set reference value, it is determined that stable data transmission is possible through the WLAN environment, and then the currently connected communication network is checked (S103). It is determined whether the remote server is being accessed through the RAS 360 (S104).

If it is determined in the above state that the biological signal measured from the subject A is transmitted to the remote server through the connection to the RAS 360 of the wireless public network, the transmission is switched to the transmission through the wireless LAN that maintains more stable and high-speed transmission. In order to block the connection with the wireless public network, the wireless LAN network is connected at the same time (S105) (S106).

Thereafter, the PDA 100 transmits the biosignal data of the subject A applied from the measurement module to the remote server through the connected WLAN, so that the subject A can be monitored remotely (S107). ).

In addition, if it is determined in step S102 that the signal strength measured from the AP 210 is less than or equal to the set reference value, the testee A determines that he is willing to leave the environment of the WLAN, and then checks the currently connected communication network (S108). It is determined whether the WLAN is connected (S109).

At this time, if it is determined that the currently connected communication network connected to a remote server via a wireless LAN is transmitting a biological signal measured from the test subject A, the communication network is disconnected from the data transmission according to the communication environment of the test subject A. In order to prevent this from occurring, the connection with the wireless LAN is blocked and the wireless public network is connected at the same time (S110) (S111).

Thereafter, the PDA 100 transmits the biosignal data of the subject A applied from the measurement module to the remote server through the RAS 360 of the connected wireless public network, so that the monitoring of the subject A is remotely performed. It is possible to (S112).

In addition, in transmitting the bio-signal to the subject A through the access of the wireless LAN, when the remote server is located in the same network environment, data transmission is performed more quickly by communication in Ad-Hoc mode.

 As described above, the present invention maintains a stable transmission to a monitoring system when a data source moves indoor wireless LAN environment and outdoor wireless public network environment, thereby providing remote patient monitoring for continuous data transmission. Provide stability and reliability.

1 is a schematic diagram illustrating a wireless data environment to which the present invention is applied.

2 is a block diagram of a portable information terminal in the configuration of FIG.

3 is a configuration diagram of a network of a wireless LAN network in FIG. 1.

4 is a diagram illustrating a network configuration of a wireless public network in FIG. 1.

5 is a flowchart of an embodiment for performing handover between a wireless LAN network and a wireless public network according to the present invention.

Claims (8)

In data transmission using a portable information terminal, The communication module of the portable information terminal measures the signal strength from the AP and compares it with a set reference value; Determining a connected communication environment in which current data transmission is maintained; And handing over a communication network according to the signal strength compared to the reference value and a currently connected communication environment to continue data transmission to a remote server. The method of claim 1, If the signal strength measured from the AP is equal to or greater than a set reference value and the currently connected communication environment is a wireless public network, the wireless public network is blocked and the user is handed over to the wireless LAN to maintain data transmission to a remote server through the wireless LAN. Handover implementation method between a WLAN and a wireless public network comprising a process. The method of claim 1, If the signal strength measured from the AP is greater than or equal to a set reference value and the currently connected communication environment is a wireless LAN, handover between the wireless LAN and the wireless public network is characterized by maintaining data transmission to a remote server through the currently connected wireless LAN. Implementation method. The method of claim 1, If the signal strength measured from the AP is equal to or less than a set reference value and the currently connected communication environment is a wireless LAN, the wireless LAN is disconnected and handed over to a wireless public network to maintain data transmission to a remote server. Implementation method of handover between WLAN and wireless public network. The method of claim 1, If the signal strength measured from the AP is equal to or less than a set reference value and the currently connected communication environment is a wireless public network, the hand between the wireless LAN and the wireless public network may maintain data transmission to a remote server through the currently connected wireless public network. Over implementation. The method of claim 1, If the connected communication environment is a wireless LAN on the same network, the method of implementing a handover between a wireless LAN and a wireless public network, characterized in that performing data transmission to a remote server in the Ad-Hoc mode. The method of claim 1, If the connected communication environment is a wireless LAN network on another network, handover between the wireless LAN and wireless public network, characterized in that to maintain the data transmission to the remote server through the infrastructure connected to the AP and AC. The method of claim 1, And a data source transmitted to the remote server is biosignal information of the examinee requiring continuous transmission.