KR101447199B1 - Method and system for minimizing delay that is owing to hard hand-off in wireless communication system - Google Patents

Abstract

A method and system for minimizing a delay occurring in FA handoff between subnetworks of different versions of a wireless communication network are disclosed. The method comprises the steps of: a) buffering packet data transmitted to a terminal in a general ATM switch network (GAN) by more than a predetermined level; And b) if a hard handoff request is generated from the terminal, the GAN checks a packet sequence confirmed by the terminal, and when the handoff is completed, the GAN does not transmit data using the buffered data in step a) And transmitting the packet to the terminal.

Wireless network, version, handoff

Description

TECHNICAL FIELD [0001] The present invention relates to a method and a system for minimizing a delay in a hard handoff in a wireless communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication system, and more particularly, to a method and system for minimizing a delay occurring in a FA handoff between subnetworks of different versions of a wireless communication network.

The mobile communication network is evolving in order of IS-95A, IS-95B, CDMA2000 1x, CDMA2000 1xEV-DO, CDMA2000 1xEV-DV, WCDMA. The IS-95A / B network separated the voice and line data from the exchange and provided the service by changing the line data to the packet data by the interworking device (IWF), and the data transmission speed was about 64Kbps to IS-95B . In addition, in the CDMA2000 1x network, a data core network (DCN) is introduced to support high-speed data service, a packet data service node (PDSN) can access the Internet, Mobility management has become possible and the data transmission speed reaches up to 153.6Kbps.

The CDMA2000 1xEV-DO network is a packet data dedicated network supporting a maximum data transmission rate of 2.4576Mbps. It is implemented together with a CDMA2000 1x system, providing voice service by CDMA2000 1x, sharing a data core network with CDMA2000 1x, - It has a terminal authentication function by the authentication device (AN-AAA) and has a function of managing the terminal position by the data location register (DLR).

Thus, the CDMA2000 1x service is a service that enables wireless Internet at a speed much faster than the speed supported by the IS-95A / B network using the IS-95C network that has evolved from the existing IS-95A / B network. The CDMA2000 1xEV-DO system began with Qualcomm's announcement of a technology called IS-95 HDR, which is completely different from the CDMA2000 1x method in terms of frequency band, but completely different from the other modulation methods. In order to provide packet data service, HDR technology adopts CDMA scheme, but adopts the modulated form of signal in completely new format and implements a kind of TDMA function in forward link. As a result, it has attracted attention because it provides a maximum data rate of 2.4 MHz using the same 1.25 MHz frequency band as IS-95.

Specifically, the forward link of the CDMA2000 1x system is transmitted with all channels multiplexed in the code direction so that all user signals occupy all frequencies simultaneously, while the forward link of the CDMA2000 1xEV-DO system transmits only one user at a time That is, time division multiple access (TDMA), having different signal transmission times for each user by transmitting another user's signal at the next moment. In this case, since the base station can set the transmission signal power for each user to the maximum value of the base station transmitter, the base station can transmit the signal with the signal most suitable for each user in the time occupied by each user, To support data rates up to 2.4576 Mbps.

Currently, the CDMA2000 1xEV-DO system is evolving from Rev.0, which was commercialized in 2002, to Rev.A, which is currently under commercialization. Rev.A is an existing 1xEV-DO Rev. 0 By upgrading only the channel card in the system, not only can provide higher peak data rate, but it also includes functions such as QoS that can not be implemented in Rev.0, Infrastructure.

However, since the current 1xEV-DO Rev.0 and Rev.A services are provided in a mixed manner, there is a problem that the quality of the communication service may deteriorate in the border region between Rev.0 and Rev.A. That is, when the Rev. A terminal moves to the Rev. 0 region in the Rev. A region, the terminal performs an inter-frequency handoff (hard handoff). That is, at the time of hard handoff, the UE has to disconnect the existing link and set a new link through another FA in the moving area, so that a delay occurs by the time corresponding to the FA transition and the data sequence number received from the existing service cell is calculated There is a problem that a delay occurs due to calculation time for sending subsequent data to the target cell.

Such a problem is caused by the evolution of the wireless communication network standard by version, which is not a problem in the CDMA2000 1xEV-DO system but a problem in other wireless communication systems such as a WCDMA system.

More specifically, in the hard handoff, unlike the soft handoff, since the established link is broken and the FA is switched to the other FA, link loss may occur at the time of handoff, Data may not be transmitted for a certain period of time. That is, as the link is instantaneously lost, the flow control is operated in the system, so that the throughput may be lowered for a certain period of time even after the link is established, and the sequence between the transmitted data and the data to be transmitted And when it is lost, it is requested to retransmit it to an upper node, which also causes a problem that the throughput of the work is lowered.

Therefore, from the viewpoint of the operator, it is possible to improve the delay in the hard handoff between versions in the border region between subnetworks (for example, between Rev.0 and Rev.A) constituting different versions of the wireless communication network, It is important to prevent.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a wireless communication system capable of minimizing a data transmission delay in hard handoff in a border region between subnetworks of different versions of a wireless communication network And a system therefor.

It is another object of the present invention to provide a method and apparatus for recognizing that a hard handoff is requested during a hard handoff between a base station and a base station in different versions of a wireless communication network, A base station of a first sub-network and a base station of a second sub-network, which enable data to be transmitted without delay due to sequence calculation by allowing a packet after the completion of transmission to be transmitted as soon as the link setting between the target base station and the terminal is completed, And to provide a system for minimizing a delay in a hard handoff in a wireless communication system capable of minimizing a delay in handoff between the base station and the base station.

According to a first aspect of the present invention, there is provided a method for minimizing a delay during a hard handoff in a wireless communication system, the method comprising the steps of: a) buffering a packet data transmitted to a terminal in a switch network by more than a predetermined level; And b) if a hard handoff request is generated from the terminal, the GAN checks a packet sequence checked by the terminal, and when the handoff is completed, the GAN uses the data buffered in step a) And transmitting the transmitted packet to the terminal.

Preferably, the GAN performs the packet sequence check in a predetermined cycle.

Also preferably, step a) is performed by a buffer installed on the board of the GAN.

More preferably, the step b) comprises the steps of: b-1) determining if the handoff is a hard handoff in the GAN when a handoff request is generated from the terminal; b-2) checking a packet sequence determined by the terminal if the handoff request is a hard handoff as a result of the determination in step b-1); And b-3) when the handoff is completed, the GAN transmits the untransmitted packet to the terminal based on the result of step b-2).

A method for minimizing delay during hard handoff in a wireless communication system according to a second aspect of the present invention includes the steps of: a) buffering packet data transmitted to a mobile station in a GAN in a buffer of a predetermined level or more; b) if the handoff request is generated from the terminal, determining whether the handoff is a hard handoff between FAs in the GAN; c) if the handoff request is a hard handoff as a result of the determination in step a), checking a packet sequence determined by the terminal at predetermined intervals; And d) determining whether the hard handoff is completed and the terminal has completed link establishment with the target base station. And e) upon completion of the link establishment with the target base station as a result of the determination in step d), the GAN transmits the untransmitted packet to the terminal based on the check result of step c) .

A system for minimizing a delay in hard handoff according to a third aspect of the present invention is a wireless communication system including a GAN for buffering packet data to be transmitted to a terminal by more than a predetermined level, When a hard handoff request is generated, checks a packet sequence determined by the terminal, and transmits the untransmitted packet to the terminal using the buffered data when the handoff is completed .

Preferably, the GAN performs the packet sequence check in a predetermined cycle.

Preferably, the GAN further comprises a buffer for buffering the packet data.

More preferably, the buffer is installed on the board of the GAN.

A system for minimizing a delay in hard handoff according to a fourth aspect of the present invention is a wireless communication system including a buffer installed on a board for buffering packet data to be transmitted to a terminal by more than a predetermined level Wherein the GAN determines whether the handoff is a hard handoff between FAs when a handoff request is generated from the terminal, and when the handoff request is a hard handoff, Checks a packet sequence determined by the terminal at a predetermined period and transmits a packet not yet transmitted to the terminal based on the check result when the terminal completes link setting with the target base station in response to the hard handoff request .

According to the present invention, when a hard handoff is requested between a base station of a first sub network and a base station of a second sub network in a border region between subnetworks of different versions of a wireless communication network, It is possible to check the sequence of the packet confirmed by the terminal until the completion of the link establishment between the target base station and the terminal and to transmit the packet after the completion of the transmission so that the data can be transmitted without a delay according to the sequence calculation , It is possible to minimize the data transmission delay in hard handoff.

Hereinafter, the present invention will be described in more detail with reference to examples of the present invention.

In a wireless communication system according to the present invention, a system for minimizing a delay during a hard handoff includes a GAN for buffering packet data to be transmitted to a terminal over a predetermined level.

The GAN according to the present invention checks a packet sequence determined by the terminal when a hard handoff request is generated from the terminal. At this time, the GAN performs the packet sequence check at a predetermined period. When the handoff is completed, the GAN transmits the untransmitted packet to the terminal using the buffered data according to the packet sequence check result.

1 is a diagram illustrating an example of a system to which a method for minimizing a delay in hard handoff is applied in a wireless communication system according to the present invention.

Referring to FIG. 1, in a wireless communication system according to a preferred embodiment of the present invention, a system to which a method of minimizing a delay during hard handoff is applied includes a first sub network and a second sub network, Systems can be configured in a mixed manner.

If the wireless communication system is a 1xEV-DO system, the first sub network may be Rev.A and the second sub network may be Rev. 0.

In this system, each of the base stations (AN (Access Network) 120 and 130) of the first sub network and the second sub network is connected to the AT (or AT) according to the standards of the first sub network and the second sub network of the wireless communication network, (Access Terminal) 110) IP network (not shown). The ANC / PCFs 131 and 132 include an SC / MM (Session Control and Mobility Management) function. The ANC / PCFs 131 and 132 exchange control signals and traffic information for packet data services as base station controllers for providing packet data services.

AN-AAA (Access Network Authentication, Authorization and Accounting) 140 performs authentication and accounting functions of the terminal 110 for the base stations 120 and 130. The Packet Data Serving Node (PDSN) 160 is connected to the BSs 120 and 130 via the ANC / PCFs 131 and 132 to provide packet data services to the MS 110. [

The system also includes a GAN 150. The GAN 150 is connected to the ANC / PCFs 131 and 132 to perform mobility maintenance / session control functions for the subscriber. In accordance with the present invention, the GAN 150 transmits packet data to be transmitted to the terminal 110 And buffers more than a predetermined level.

Advantageously, the GAN 150 includes a buffer installed on the board to buffer the packet data.

When a handoff request is generated from the SS 110, the GAN 150 determines whether the handoff is a hard handoff between the FAs. As a result of the determination, if the handoff request is a hard handoff, the GAN 150 checks a packet sequence checked by the terminal 110 every predetermined time. Thereafter, when the UE completes the link establishment with the target base station in response to the hard handoff request, the GAN 150 transmits an untransmitted packet to the UE 110 according to the check result.

Accordingly, when the system performs a hard handoff between the first sub network base station 120 and the second sub network base station 130 of the wireless communication system in a border region of a sub-network constituting a different version of the wireless communication network, a link is established It is possible to check the sequence of the packet confirmed by the terminal until the completion of the link establishment between the target base station 130 and the terminal 110 and to transmit the packet after the transmission is completed. . ≪ / RTI >

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method and a system for minimizing delay in hard handoff in a wireless communication system according to the present invention will be described in detail with reference to the accompanying drawings.

Fig. 2 is a flow chart for explaining the operation of the apparatus shown in Fig. 1. Fig.

Referring to FIG. 2, the GAN 150 according to the present invention includes a buffer mounted on an APP board to minimize delay in hard handoff according to the present invention, The data is buffered (S1).

The terminal 110 accesses the base station 130 of the second subnetwork as the target base station from the base station 120 of the first subnetwork as the source base station so that the terminal 110 determines handoff (S2) .

If the handoff is determined, the SS 110 transmits a Route Update Message to the BS 120 of the first sub-network for handoff (S3).

When receiving a route update message for handoff from the SS 110 at the BS 120 of the first sub-network designated as a boundary cell. The base station 120 of the first sub-network requests handoff to the GAN 150 through the source ANC / PCF 131 (S4).

Upon receiving the handoff request, the GAN 150 determines whether the handoff is a hard handoff between FAs, that is, a handoff from a version of the first subnetwork to a version of the second subnetwork (S5) . For example, the GAN 150 compares the PN included in the route update message with the PN of the target base station requested for handoff to determine whether the handoff is a hard handoff.

Then, the GAN 150 requests the target ANC / PCF 132 of the handoff request to the base station 130 of the second sub network, which is the target AN, as a result of the handoff request. Off request is a hard hand-off, it checks a packet sequence determined by the terminal at predetermined intervals (S5, S6).

When handoff is completed between the UE 110 and the target base station 130 and a handoff completion message is received from the target base station 130, The GAN 150 transmits an untransmitted packet to the terminal 110 based on the check result of step S7).

Therefore, in the wireless communication system, when a hard handoff between the base station of the first sub-network and the base station of the second sub-network is requested in the wireless communication system in the border region of the sub-network constituting a different version of the wireless communication network, So as to check the sequence of the packet confirmed by the terminal until the link is established and to transmit the packet after the completion of the transmission as soon as the link setting between the target base station and the terminal is completed, Data can be transmitted.

As described above, according to the present invention, there is provided a method of minimizing delay in hard handoff in a wireless communication system capable of minimizing a data transmission delay in hard handoff in a border region of a subnetwork constituting a different version of a wireless communication network, and System can be realized.

Although the present invention has been described in detail by way of the above embodiments, the present invention is not limited thereto, but can be modified or improved within the ordinary knowledge of those skilled in the art.

Further, the present invention recognizes that a hard handoff is requested during a hard handoff between a base station of a first sub-network and a base station of a second sub-network in a wireless communication system in a border region of a sub- , It checks the sequence of the packet confirmed by the terminal until the link is established and enables to transmit the packet after the completion of the transmission as soon as the link setting between the target base station and the terminal is completed, Since it is intended to minimize the data transmission delay in the hard handoff, it is an industrially applicable invention since the possibility of market or business is sufficient and it can be practically and practically carried out.

1 is a diagram illustrating an example of a system to which a delay minimization method in a hard handoff in a wireless communication system according to an embodiment of the present invention is applied.

Fig. 2 is a flow chart for explaining the operation of the apparatus shown in Fig. 1. Fig.

Description of the Related Art

110: AT 120: Source AN Rev.A

130: Target AN Rev.01: Source ANC / PCF

132: target ANC / PCF 140: AN AAA

150: GAN 160: PDSN

Claims (10)

In a wireless communication system, And a GAN (General ATM switch Network) buffering packet data to be transmitted to the terminal at a predetermined level or higher; The GAN, When a hard handoff request is generated from a first subnetwork to a second subnetwork of a different version of the wireless communication system from the terminal, a packet sequence checked by the terminal is checked, and the hard handoff And transmits the untransmitted packet to the terminal using the buffered data when the completion of the hard handoff is completed. The method according to claim 1, The GAN, And checks a packet sequence confirmed by the terminal at a predetermined period. 3. The method according to claim 1 or 2, The GAN, And a buffer for buffering the packet data. The method of claim 3, The buffer includes: Wherein the system is installed on a board of the GAN. In a wireless communication system, A GAN including a buffer installed on a board for buffering packet data to be transmitted to a terminal by more than a predetermined level; The GAN, When a handoff request is generated from a first sub-network to a second sub-network constituting a different version of the wireless communication system from the terminal, it is determined whether the hand-off is a hard handoff between FAs, Wherein the control unit checks a packet sequence determined by the MS in a predetermined period when the request is a hard handoff and if the MS completes the link establishment with the target BS in response to the hard handoff request, And transmits the transmitted packet to the mobile station. A method for minimizing delay in hard handoff in a wireless communication system, a) buffering packet data transmitted to a terminal in the wireless communication system beyond a predetermined level; And b) When a hard handoff request is generated from the MS, the GAN checks a packet sequence checked by the MS, and when the handoff is completed, And transmitting the packet to the terminal. The method according to claim 6, The GAN, And checks a packet sequence determined by the terminal at a predetermined period. The method according to claim 6, The step a) Wherein the buffer is provided by a buffer installed in the GAN board. 9. The method according to any one of claims 6 to 8, The step b) b-1) determining whether the handoff is a hard handoff in the GAN when a handoff request is generated from the terminal; b-2) checking a packet sequence determined by the terminal if the handoff request is a hard handoff as a result of the determination in step b-1); And b-3) when the handoff is completed, the GAN transmits, to the terminal, an untransmitted packet based on the result of step b-2). A method for minimizing delay during handoff. A method comprising: a) buffering packet data transmitted to a terminal by a GAN in a wireless communication system in a buffer of the board at a predetermined level or higher; b) if the handoff request is generated from the terminal, determining whether the handoff is a hard handoff between FAs in the GAN; c) if the handoff request is a hard handoff as a result of the determination in step a), checking a packet sequence determined by the terminal at predetermined intervals; And d) determining whether the hard handoff is completed and the terminal has completed link establishment with the target base station; e) Upon completion of the link establishment with the target BS, the GAN transmits the untransmitted packet to the terminal based on the check result of step c) as a result of the determination in step d) Wherein a delay is minimized in a hard handoff in a wireless communication system.

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