KR100705599B1 - Apparatus and method for hand-off of terminal in wireless broadband internet system - Google Patents

Abstract

In the portable Internet system according to the present invention, a handoff method of a terminal and a device thereof allow the terminal of the portable Internet system to request a handoff to one base station that satisfies the best QoS for a service currently being performed or to be performed. Various QoS required by the user may be provided to the terminal user, and communication traffic of the portable Internet system generated when the terminal performs handoff may be reduced.

Description

A handoff method of a terminal in a portable internet system and a device therefor {APPARATUS AND METHOD FOR HAND-OFF OF TERMINAL IN WIRELESS BROADBAND INTERNET SYSTEM}

1 is a diagram illustrating a handoff process of a terminal in a portable internet system according to the prior art.

2 is a block diagram showing a portable Internet system according to the present invention.

3 is a block diagram showing a terminal according to the present invention.

4 is a signal flow diagram illustrating a handoff process of a portable Internet system according to an embodiment of the present invention.

5 is a flowchart illustrating a handoff process of a terminal according to an embodiment of the present invention.

6 is a flowchart illustrating a handoff process of a terminal according to another embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

100: terminal 200: BS

300: ACR

The present invention relates to a handoff method of a terminal and a device thereof in a portable internet system.

The Wireless Broadband Internet system allows wireless devices such as notebooks, personal digital assistants, and smartphones to be provided at any time, anywhere, at any time, while stationary and moving (over 60 km / h). Make sure

In such a portable Internet system, when a terminal leaves a cell boundary of a base station currently connected for communication with a counterpart terminal, the terminal communicates with a counterpart terminal (for example, a smartphone, a laptop, a desktop, a server, etc.). In order to perform without interruption, handoff is performed to a new base station.

1 is a diagram illustrating a handoff process of a terminal in a portable internet system according to the prior art.

As shown in FIG. 1, when a terminal is currently communicating with a counterpart terminal through a base station (hereinafter, referred to as a 'BS'), when the terminal moves out of a service area of the BS, the terminal is received from the BS. If the signal size is less than the set signal size is determined (S11).

When the UE determines that the signal size received from the BS is less than or equal to the set signal size, the UE scans neighbor BSs for handoff (S12), and performs carrier to interference and noise ratio (CINR) included in each scanned BS. Analyze (S13).

In addition, the UE determines whether the CINR value of the scanned BSs is greater than or equal to the CINR value of the currently serving BS (S14), and the target BS to perform handoff on the BS having a value greater than or equal to the CINR value of the scanned BS. To select. The terminal selecting the target base station transmits a signal for requesting handoff to the selected target BS to the currently serving BS (S15).

The terminal receives a handoff response signal corresponding to the transmitted handoff request signal from the serving BS (S16), and performs communication with the other terminal without interruption through the selected target BS.

On the other hand, if the terminal performing such a handoff has a plurality of BSs including CINR values equal to or greater than the CINR value of the currently serving BS among the scanned neighbor BSs, all of the BSs are selected as target BSs, and the selected target BS is selected. The all-inclusive handoff request signal is transmitted to the currently serving BS.

Accordingly, the portable Internet system allows the currently serving BS to transmit a handoff request signal to a plurality of target BSs according to a handoff request signal received from the terminal to an access control router (hereinafter referred to as 'ACR'). In addition, the ACR receiving the ACR transmits a handoff request signal to the plurality of target BSs, and then selects one of the target BSs to which the response signal is received and provides the terminal to the target BS.

However, the handoff method of the terminal in such a portable Internet system has a problem of increasing the communication traffic of the portable Internet system due to the communication between the ACR and the plurality of target BSs.

In addition, such a handoff method of the terminal has a limitation that does not satisfy various QoS as the target BS is selected based on the CINR only.

Accordingly, the present invention is to solve the above problems according to the prior art, an object of the present invention is to provide a portable Internet system for the terminal of the portable Internet system to perform a handoff to a target base station that satisfies various QoS required by the user In the present invention, a handoff method and an apparatus thereof are provided.

Another object of the present invention is to provide a method and apparatus for handoff of a terminal in a portable internet system to reduce communication traffic weighted as the terminal performs handoff in the portable internet system.

In the portable Internet system according to an aspect of the present invention for achieving the above object, the handoff device of the terminal, the storage unit for storing the reference signal size and QoS parameters for each service; If the size of the signal received from the access base station is less than or equal to the reference signal size, the neighboring base station is scanned, and the best QoS parameter for the service currently being performed or to be performed among the scanned base stations with reference to the QoS parameter stored in the storage unit. And a control unit for selecting a base station having a value as a target base station of the handoff.

The storage unit further stores a threshold value for each QoS parameter for each service.

The control unit selects, as a target base station, a base station having a maximum value of a QoS parameter having the highest weight of a service currently being performed or to be performed, which is greater than or equal to a threshold stored in the storage unit.

The controller selects, as the handoff target base station, the base station having the largest number of QoS parameters that are equal to or greater than the threshold value among at least one QoS parameter value.

The control unit transmits a handoff request signal including identification information of the selected target base station to the currently connected base station.

The QoS parameters include a carrier to interference and noise ratio (CINR), a receive signal strength indicator (RSSI), a round trip delay (BS RTD), a minimum data rate (MDR), a mean datr rate (MDR), and a relative delay (RD). At least one of the parameters.

In addition, a handoff apparatus of a terminal in a portable Internet system according to another aspect of the present invention includes a storage unit for storing a reference signal magnitude and a threshold value for each QoS parameter for each service; If the size of the signal received from the access base station is less than or equal to the reference signal size, at least one QoS for each of the scanned base stations, currently performed or to be performed, is scanned by neighboring base stations and by referring to the QoS parameters of the storage unit. And a control unit for selecting a base station having the largest number of parameters whose parameter value is greater than or equal to the threshold value as a handoff target base station.

On the other hand, in the portable Internet system according to another aspect of the present invention for achieving the above object, the handoff method of the terminal, while moving from the service area of the access base station, determining the magnitude of the signal received from the access base station step; If the signal is determined to be less than or equal to a preset reference signal size, scanning a neighboring base station; Selecting, among each of the scanned base stations, a base station having the best QoS parameter value for a service currently or to be performed as a handoff target base station.

In the selecting of the handoff target base station, the handoff target base station selects a base station having a maximum value equal to or greater than a preset threshold for the QoS parameter having the highest weight in the currently performing or performing service.

The selecting of the handoff target base station selects a base station having the largest number of QoS parameters whose at least one QoS parameter value is greater than or equal to the threshold value as the handoff target base station.

In addition, the handoff method of the terminal in the portable Internet system further includes the step of transmitting a handoff request signal including the identification information of the selected target base station to the access base station.

The QoS parameter includes at least one of CINR, RSSI, BS RTD, MDR, MDR and RD parameters.

The handoff method of a terminal in a portable internet system according to another embodiment of the present invention includes: determining a magnitude of a signal received from the access base station while moving from a service area of the access base station; If the signal is determined to be less than or equal to a preset reference signal size, scanning a neighboring base station; Selecting, as the handoff target base station, the base station having the largest number of QoS parameters in which at least one or more QoS parameter values of the currently executed or performed service are equal to or greater than a predetermined threshold value among the scanned base stations.

Hereinafter, a handoff method and a device of a terminal in a portable Internet system according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram showing a portable Internet system according to the present invention.

As shown in FIG. 2, the portable Internet system includes a subscriber portable terminal (hereinafter referred to as 'terminal' 100), a base station (hereinafter referred to as 'BS') 200, and an access control router. : May be referred to as 'ACR') 300.

Here, the terminal 100 is wirelessly connected to the BS 200, and the BS 200 is connected to the ACR 300 to perform a communication service between the terminal 100.

In the portable Internet system, while the terminal 100 performs a communication service with the counterpart terminal 100 through the currently connected BS A 200a, when the user moves in the counterpart area of the BS A 200a, Determines that the size of the signal received from the BS A 200a is less than or equal to the preset reference signal size, performs a peripheral BS 200 scan to perform communication with the counterpart terminal 100 without interruption, and scans the neighboring BS. A handoff request signal to one of the target BSs (eg BS B 200b) is sent to BS A 200a.

When the BS A 200a receives the handoff request signal from the terminal 100 to the BS B 200b, the BS A 200a transmits the handoff request signal back to the ACR 300 so as to correspond to the handoff signal received from the ACR 300. The response signal is provided to the terminal 100.

Accordingly, even if the terminal 100 leaves the counterpart area of the BS A 200a, the terminal 100 performs communication with the counterpart terminal 100 without interruption through the connection with the BS B 200b.

In such a portable Internet system, the BS 200 and the terminal 100 are connected in an orthogonal frequency division multiplexing (OFDM) system, an orthogonal frequency division multiplexing access (OFDMA) system, or a time division multiple access (TDMA) system. Perform communication service through allocated bandwidth.

In addition, the portable Internet system supports an uplink scheduling algorithm for guaranteeing a quality of service (QoS) of a service between the BS 200 and the terminal 100. In other words, the portable Internet system allows the bandwidth of the uplink to be allocated through different scheduling algorithms according to the services provided between the BS 200 and the terminal 100.

The uplink scheduling algorithm includes an unsolicited grant service (USG) algorithm, a real-time polling service (rtPS) algorithm, a non-real-time polling service (nrtPS) algorithm, and a best effect (BE) algorithm.

The USG algorithm is an algorithm for providing a service that is very sensitive to time delay of data transmission, such as voice call service according to Voice of IP (VoIP), so that the BS 200 continuously guarantees the uplink bandwidth of the terminal 100. do.

In the USG algorithm, the allocation period and the size of the bandwidth of the uplink are made by negotiation between the terminal 100 and the BS 200 at the first connection, and when the negotiation is completed, even if there is no additional request of the terminal 100, the BS It ensures the terminal 100 of the bandwidth of the negotiated uplink (200).

The rtPS algorithm is an algorithm for providing a service for transmitting image data such as a video stream, and allows the BS 200 to variably allocate an uplink bandwidth of the terminal 100.

While the USG algorithm allows the BS 200 to continuously guarantee the uplink bandwidth of the terminal 100 periodically, the rtPS algorithm continuously requests the bandwidth according to the capacity of the data to be transmitted by the terminal 100, and the BS 200 The bandwidth required from the terminal 100 is variably allocated.

The nrtPS algorithm is an algorithm for providing a service in which a time delay of data transfer is not sensitive, such as a file transfer protocol (FTP) service, and while a connection between the BS 200 and the terminal 100 is maintained. The 100 always transmits a bandwidth request message to the BS 200 and the BS 200 allocates the bandwidth of the requested size to the terminal 100.

The BE algorithm is an algorithm for providing a service such as a web service, which is not sensitive to a time delay of data transmission but has a persistent and bursty characteristic, and the terminal 100 transmits it through an upper application. Whenever data occurs, the BS 200 requests the required uplink bandwidth and transmits the data using the bandwidth allocated from the BS 200.

Meanwhile, in selecting the target BS 200, the terminal 100 of the portable Internet system, according to the uplink scheduling algorithm, thresholds for respective QoS parameter values according to a service currently being performed or to be performed. The BS 200 including the highest QoS parameter value may be selected as the target BS 200 among the BSs 200 including the QoS parameters satisfying a value equal to or greater than the preset threshold.

3 is a block diagram illustrating a terminal according to the present invention.

As shown in FIG. 3, the terminal may include a transceiver, a controller, and a storage.

The transceiver 110 of the terminal 100 performs wireless communication with the BS 200.

The controller 120 scans the neighbor BS 200 according to the signal size of the BS 200 received through the transceiver 110, and selects one target BS 200 from the scanned neighbor BSs 200. Perform a handoff. The control unit 120 includes a scanning unit 130 that scans the neighboring BS 200 and checks QoS parameters included in each scanned terminal 100.

Here, in selecting the target base station, the control unit 120 selects the neighbor BS 200 having the best value for the QoS parameter having the highest weight in the service currently being performed or to be performed as the target BS 200, At least one QoS parameter value for a service that is currently being performed or to be performed is selected as the handoff target BS 200 as the neighbor BS 200 having the largest number of QoS parameters whose threshold number is greater than or equal to the threshold of the storage 140. .

The storage 140 stores a threshold for at least one QoS parameter and a reference signal size for the signal size received from the BS 200.

Referring to the operation of the terminal 100 having such a configuration, first, when the control unit 120 of the terminal 100 is moved from the range of the BS 200 that is currently connected to the service, the transmission and reception unit 110 When the signal size received from the BS 200 is determined to be less than or equal to the reference signal size of the storage 140, the scanning unit 130 scans the neighboring BSs 200 through the transceiver 110.

The scanning unit 130 scans the neighbor BSs 200 through the transceiver 110 and analyzes the scanned neighbor BSs 200 to determine QoS parameters included in each neighbor BS 200. Here, the QoS parameters include a carrier to interference and noise ratio (CINR), a receive signal strength indicator (RSSI), a round trip delay (BS RTD), a minimum data rate (MDR), a mean datr rate (MDR), and a relative delay (RD) parameter. And so on.

When the QoS parameters of the respective neighboring BSs 200 are determined by the scanning unit 130, the controller 120 determines the best target BS 200 among the neighboring BSs 200 scanned according to the determined QoS parameter values. Select.

Herein, in selecting the target BS 200, the controller 120 selects the neighbor BS 200 including the best value, that is, the highest value, for the QoS parameter having the highest weight in the service currently being performed or to be performed. The target BS 200 may be selected.

In addition, the control unit 120 includes the best combination of at least one or more QoS parameters according to the service currently being performed or performed, that is, the periphery including the QoS parameter having the maximum value over the threshold of the storage unit 140. BS 200 may be selected as a target BS 200.

For example, if the type of service currently being performed or to be performed is a real-time service such as a telephone call, the controller 120 assigns the highest weight to QoS parameters related to delay, such as BS RTD, RD, and the like. The neighbor BS 200 having the best value for the target BS 200 may be selected.

In addition, if the type of service currently being performed or to be performed is a data service such as a short message transmission, the control unit 120 assigns the highest weight to the QoS parameter related to the data transmission and has the best value for the QoS parameter. Select 200 as the target BS 200.

On the other hand, when the control unit 120 selects the target BS 200 having the best combination for at least one or more QoS parameters, if the service QoS parameter currently being performed or to be performed is CINR, RSSI and BS RTD, each value All of these select the peripheral BS 200 that is greater than or equal to the threshold stored in the storage 140 first. The controller 120 selects the neighbor BS 200 as the target BS 200 among the selected neighbor BSs 200 including the highest value for each of the CINR, RSSI, and BS RTD values.

When the target BS 200 is selected in this way, the controller 120 generates a handoff request signal including the selected target BS 200, and transmits the generated handoff request signal to the BS (transmitter 110). 200).

The controller 120 receives a handoff response signal corresponding to the transmitted handoff request signal from the BS 200 through the transceiver 110.

Accordingly, when the terminal 100 receives the handoff response signal from the BS 200 through the operation of the above configurations, the terminal 100 may access the target BS 200 to perform communication with the counterpart terminal 100 without interruption. .

4 is a signal flowchart illustrating a handoff process of the portable Internet system according to an embodiment of the present invention.

As shown in FIG. 4, the terminal 100 is connected to the BS A 200a and is performing communication service with the counterpart terminal 100 (S101), and is deviated from the service area of the BS A 200a by the user. Can be moved to.

In this case, the terminal 100 analyzes whether the size of the signal received from the BS A 200a is less than or equal to the preset reference signal size (S102), and if it is determined that the signal is less than or equal to the preset reference signal size, performing handoff. The neighbor BSs 200 are scanned for operation (S103).

The terminal 100 analyzes the scanned neighbor BSs 200, grasps QoS parameters included in each BS 200, and selects the best target BS 200 to perform a handoff (S104).

Here, in selecting the target BS 200, the terminal 100 selects the neighbor BS 200 including the best value, that is, the highest value, for the QoS parameter having the highest weight in the service currently being performed or to be performed. The target BS 200 is selected as the target BS 200 or the neighbor BS 200 having the largest number of QoS parameters for which at least one QoS parameter value for a service currently being performed or to be performed is greater than or equal to a preset threshold. You can choose. In FIG. 4, for example, the terminal 100 may select the BS B 200b as the target BS 200.

In addition, the terminal 100 generates a handoff request signal including the selected target BS 200, that is, the BS B 200b, and transmits the generated handoff request signal to the BS A 200a (S105).

Accordingly, the BS A 200a transmits a handoff request signal received from the terminal 100 to the ACR 300 (S106), and the ACR 300 handsoff the terminal 100 to the BS B 200b. The request signal is transmitted (S107).

When the handoff request signal is received, the BS B 200b transmits a handoff response signal corresponding to the received handoff request signal to the ACR 300 after determining whether to respond to the handoff request signal (S108). Here, the BS B 200b may transmit a handoff response signal including a new IP address to be provided to the corresponding UE 100 requesting handoff to the ACR 300.

When the handoff response signal is received from the BS B 200b, the ACR 300 transmits the received signal to the BS A 200a (S109), so that the corresponding signal is provided to the terminal 100 (S110).

When the terminal 100 transmits a handoff request signal and receives a handoff response signal corresponding to the corresponding handoff request signal from BS A 200a, the terminal 100 uses an IP address included in the received handoff response signal. The BS B 200b may be connected to perform communication with the counterpart terminal 100 without interruption (S111).

5 is a flowchart illustrating a handoff process of a terminal according to an embodiment of the present invention.

As shown in FIG. 5, when the terminal 100 moves in a direction away from the service area of the currently connected BS 200, whether the size of a signal received from the BS 200 is less than or equal to a preset reference signal size is determined. It is determined (S201).

If it is determined that the size of the signal received from the BS 200 is less than or equal to the preset reference signal size, the terminal 100 scans the neighboring BSs 200 (S202).

When the neighboring BSs 200 are scanned, the terminal 100 analyzes the scanned neighboring BSs 200 to determine QoS parameters included in each BS 200 (S203).

The terminal 100 selects, as the target BS 200, the neighbor BS 200 having the maximum value for the QoS parameter having the highest weight in the service currently being performed or to be performed, among the identified QoS parameters (S204). .

The terminal 100 generates a handoff request signal including the selected target BS 200 and transmits it to the BS 200 (S205), and receives a handoff response signal corresponding to the transmitted handoff request signal (S206). ).

The terminal 100 receiving the handoff response signal as described above connects to the target BS 200 and performs communication with the counterpart terminal 100 without interruption.

6 is a flowchart illustrating a handoff process of a terminal according to another embodiment of the present invention.

As shown in FIG. 6, when the terminal 100 moves in a direction away from the service area of the currently connected BS 200, whether the size of a signal received from the BS 200 is less than or equal to a preset reference signal size is determined. It is determined (S301).

If it is determined that the size of the signal received from the BS 200 is less than or equal to the preset reference signal size, the terminal 100 scans the neighboring BSs 200 (S302).

When the neighboring BSs 200 are scanned, the terminal 100 analyzes the scanned neighboring BSs 200 to determine QoS parameters included in each of the BSs 200 (S303).

In addition, the terminal 100 may include a neighbor BS including the best combination of at least one or more QoS parameters according to a service currently being performed or to be performed, that is, a QoS parameter having a maximum value over a preset threshold. 200 may be selected as the target BS 200 (S304).

The terminal 100 generates a handoff request signal including the selected target BS 200 and transmits the generated handoff request signal to the BS 200 (S305), and receives a handoff response signal corresponding to the transmitted handoff request signal (S306). ).

As such, the terminal 100 receiving the handoff response signal may access the target BS 200 and perform communication with the counterpart terminal 100 without interruption.

The method and apparatus for handoff of a terminal in a portable internet system according to the present invention as described above, by allowing the terminal of the portable internet system to request a handoff to the base station that satisfies the best QoS for the service currently being performed or to be performed. In this case, various QoS required by the terminal user may be provided to the terminal user.

In addition, in the portable Internet system according to the present invention, the handoff method of a terminal and a device thereof allow the terminal to request handoff to one base station that satisfies the best QoS for a service currently being performed or to be performed. It is possible to reduce the communication traffic of the portable Internet system generated when performing the off.

Claims (13)

A handoff device of a terminal in a portable internet system, A storage unit which stores the reference signal size and the QoS parameter for each service; Wow If the size of the signal received from the access base station is less than or equal to the reference signal size, the neighboring base station is scanned, and the best QoS parameter for the service currently being performed or to be performed among the scanned base stations with reference to the QoS parameter stored in the storage unit And a control unit for selecting a base station having a value as a target base station of the handoff. The method of claim 1, The storage unit, Handoff device of the terminal further stores a threshold for each of the QoS parameters for each service. The method of claim 1, The control unit, A handoff apparatus of a terminal for selecting a base station having a maximum value of a QoS parameter having the highest weight of a service currently being performed or to be performed and having a maximum value greater than or equal to a threshold stored in the storage unit. The method of claim 1, The control unit, And a base station having the largest number of QoS parameters that is equal to or larger than a threshold stored in the storage unit among at least one QoS parameter value, as a handoff target base station. The method of claim 1, The control unit, And a handoff request signal including the identification information of the selected target base station to the access base station. The method of claim 1, The QoS parameter is At least one of carrier to interference and noise ratio (CINR), receive signal strength indicator (RSSI), round trip delay (BS RTD), minimum data rate (MDR), mean datr rate (MDR), and relative delay (RD) parameters Handoff device of the terminal comprising. A handoff device of a terminal in a portable internet system, A storage unit for storing a reference signal magnitude and a threshold for each of the service-specific QoS parameters; Wow If the size of the signal received from the access base station is less than or equal to the reference signal size, at least one QoS for each of the scanned base stations, currently performed or to be performed, is scanned by neighboring base stations and by referring to the QoS parameters of the storage unit. And a control unit for selecting a base station having the largest number of parameters whose parameter value is greater than or equal to the threshold value as a handoff target base station. In a handoff method of a terminal in a portable internet system, Determining a magnitude of a signal received from the access base station while moving from a service area of the access base station; If the signal is determined to be less than or equal to a preset reference signal size, scanning a neighboring base station; And Selecting a base station having the best QoS parameter value for a service currently being performed or to be performed as the handoff target base station among the scanned base stations. The method of claim 8, Selecting the handoff target base station, A method for handoff of a terminal that selects a base station having a maximum value over a preset threshold as a handoff target base station with respect to a QoS parameter having the highest weight in a service currently being performed or to be performed. The method of claim 8, Selecting the handoff target base station, And a base station having the largest number of QoS parameters whose at least one QoS parameter value is greater than or equal to the threshold value as a handoff target base station. The method of claim 8, And transmitting a handoff request signal including the identification information of the selected target base station to the access base station. The method of claim 8, The QoS parameter is Handoff method of the terminal including at least one of the CINR, RSSI, BS RTD, MDR, MDR and RD parameters. In a handoff method of a terminal in a portable internet system, Determining a magnitude of a signal received from the access base station while moving from a service area of the access base station; If the signal is determined to be less than or equal to a preset reference signal size, scanning a neighboring base station; And And selecting, as the handoff target base station, the base station having the largest number of QoS parameters, wherein the at least one QoS parameter value for the service currently being performed or to be performed is equal to or greater than a predetermined threshold value among the scanned base stations. A handoff method of a terminal in an internet system.

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