KR20090066151A - Method of call control and apparatus thereof - Google Patents

Abstract

A call control method and an apparatus thereof based on QoS are provided to perform a call request or a channel allocation by differentiating a call control according to a drop rate between services or a drop rate between neighboring cells. A QoS output unit(210) produces a first wireless network QoS(Quality of Service) every window. If the QoS does not reach the standards QoS, a time window controller(220) sets up the next time window as perpendicular the time window. In case the second wireless network which is the first wireless network and different kind and the possible with data communications lice mobile terminal request the house for the time window, a call control function(230) performs the first vertical handoff to the second wireless network.

Description

Method of call control and apparatus therefor {Method of Call Control and Apparatus}

The present invention relates to a method and apparatus for controlling a call for a call request in a mixed network of heterogeneous communication networks, and more particularly, to a method and apparatus for controlling a call in consideration of fairness between adjacent cells and services.

The present invention is derived from the research conducted as part of the IT growth engine technology development project of the Ministry of Information and Communication and the Ministry of Information and Telecommunications Research and Development. Networking technology development].

With the development of mobile communication technology, technologies related to interworking and handoff between heterogeneous communication networks according to different radio access technologies (RAT) have emerged.

Handoff between heterogeneous communication networks means that the service can be continuously received after a slight delay or no interruption of service in the second communication network while receiving the service in the first communication network. In particular, in the 3GPP (3rd Gerneration Partnership Project) standardization research group and IEEE 802 working group, standards for interworking between a 3GPP mobile communication network and a wireless local area network (WLAN) are being developed.

In the mobile communication, handoff occurs between cells according to the movement of the mobile terminal, and when the mobile terminal enters a new cell, it may be impossible to allocate radio resources due to congestion. Therefore, efficient allocation of radio resources is required. In particular, there is a need for efficient allocation of radio resources in hot-spots.

Accordingly, an object of the present invention is to provide a call control method and apparatus for improving service resource utilization and system throughput (call request) to provide a continuous service while moving. The present invention also provides a call control method and apparatus for efficiently allocating or accepting a call by varying call control according to a blocking rate between adjacent cells or a blocking rate between services.

In addition, the present invention provides a call control method and apparatus for preventing the blocking of the reverse vertical handoff of a vertical handoff call.

The call control method according to the present invention for achieving the above object is a call control method for a call request from the control station of the first wireless network performing data communication with the mobile terminal, the first periodically every time window Calculating a Quality of Service (QoS) with at least one parameter of traffic change, available bandwidth, service availability, quality of real-time and non-real-time services, and call blocking rate of a wireless network, and generating a next time window according to the QoS. Setting one of a general time window and a vertical time window, receiving a call request of a mobile terminal capable of data communication with a second wireless network heterogeneous with the first wireless network during the vertical time window, and setting the call to the second time window. A first vertical handoff to a wireless network.

Meanwhile, the call control device according to the present invention is a call control device for a call request of a mobile terminal in a first wireless network performing data communication with the mobile terminal, and periodically changes the traffic of the first wireless network every time window, A QoS calculator which calculates a Quality of Service (QoS) with at least one parameter of available bandwidth, service availability, quality of real-time and non-real-time services, and call blocking rate; A time window control unit configured to set a vertical time window, and a first vertical handoff to a second wireless network when a call request of a mobile terminal capable of data communication with a second wireless network heterogeneous with the first wireless network is performed during the time window; And a call controller.

According to the present invention, the quality of each service is improved by varying channel assignments according to real-time and non-real-time services as multimedia services are activated. In addition, the call control is differentiated according to the new call and the handoff call, and the vertical handoff is performed according to the QoS value such as the call blocking rate to prevent the high load traffic cell, that is, the hot spot cell. In addition, according to the present invention, as the call blocking rate is increased, the processing power for a new call or a handoff call can be improved through vertical handoff, and other communication networks can be efficiently used.

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

1 is a schematic diagram of a communication network system including a call control device according to the present invention. It is a schematic diagram of call acceptance when a mobile terminal exists in an integrated network in which a 3G communication network and a WLAN network overlapped with a 3G communication network exist.

Of course, it may also include a wireless network that can be included in the integrated wireless network other than the 3G communication network and WLAN network.

The mobile terminal 20 may be connected to each of the 3G communication network 30 and the wireless LAN network 40 in the present embodiment as a device that requests and provides a service with mobility.

The 3G (Generation) communication network 30 is a third generation communication network capable of providing data services, providing global roaming, and having a maximum data rate of 2Mbps. W-CDMA (UMTS) and CDMA 2000 Mx (IS-2000).

The 3G communication network system includes a base station 110 wirelessly connected to the mobile terminal 20 and a call control device 10 for controlling the base station and controlling call such as call acceptance and rejection of a call request of the mobile terminal 20. do.

As a basic service, the mobile terminal 20 requests a new new call service in the 3G communication network 30 and a handoff process in which a service being used in an adjacent 3G communication network moves to the current 3G communication network 30. There is).

The WLAN network 40 provides a service between the LAN-based wired network and the mobile terminal 20 using radio frequency. The WLAN network system performs call control such as control of the WLAN base station 130 and the WLAN base station 130 wirelessly connected to the mobile terminal 20 and call acceptance and rejection of the call request of the mobile terminal 20. WLAN network call control device 120 is included.

There is a process 170 in which the mobile terminal 20 requests a new new call service in the WLAN network 40.

The wireless service in the integrated network is a first handoff process 180 in which the service used in the 3G communication network 30 moves to the WLAN network 40 and the 3G communication network 30 in the WLAN network 40. There is a second handoff process 190 in which the service moves.

2 is a block diagram of the internal structure of the call control device 10 according to an embodiment of the present invention.

Referring to FIG. 2, the call control device 10 includes a QoS calculator 210, a time window controller 220, and a call controller 230.

The QoS calculation unit 210 periodically performs QoS by at least one parameter of traffic change, available bandwidth, service availability, delay time, real-time and non-real-time service quality, and call blocking rate of the 3G communication network 30 at every time window. (Quality of Service) can be calculated. Here, QoS refers to a value that can be measured and expressed quantitatively as a resource element that can be controlled to ensure a certain level of quality of service.

The time window controller 220 receives the QoS from the QoS calculator 210 and sets the next time window according to the QoS. Setting values include normal time window and vertical time window. When there is a call request of the mobile terminal 20 during the vertical time window, the first vertical handoff is performed to the WLAN network.

The call controller 230 controls the call request according to whether or not the current time window is a vertical time window. The call controller 230 includes a channel control module 240 for controlling a channel and a standby buffer 250 for waiting for a non-real time handoff call.

There may be two kinds of call request: a new call requesting a new connection in the communication network and a handoff call requesting a connection in an adjacent cell. In addition, the call request may be a call request for a real-time service and a call request for a non-real-time service. That is, a call request may include a new call request for a real time service (hereinafter referred to as 'real time new call'), a new call request for a non real time service (hereinafter referred to as a 'non real time new call'), and a handoff call request for a real time service (hereinafter referred to as 'real time new call'). , 'Real-time handoff call'), and a handoff call request for the non-real-time service (hereinafter, 'non-real-time handoff call').

The call controller 230's response to the call request may be call acceptance and rejection, vertical handoff, and call waiting. When accepting a call request, it allocates a channel for service. Vertical handoff is to transfer a call to another network, and call waiting is temporarily suspended.

The channel control module 240 controls the channel according to the call characteristic and adjusts the amount of the channel. Wait buffer 250 is a temporary place for waiting for a call.

3 is a diagram illustrating a call characteristic model of a cell in an integrated network. The call is controlled by the call controller 230 of FIG. 2 and a channel is allocated according to the characteristics of the call.

Referring to FIG. 3, in this embodiment, the total number of channels of one cell of the 3G communication network is Ck 300. The total channel Ck (300) is an Rk (310) channel that is dedicated to real-time services, an NRk (320) channel that is dedicated to non-real-time services, and a real-time service and a non-real-time service. The channel may be divided into an Sk 330 channel.

Real-time new calls can be assigned only to the Rk 310 channel that accepts real-time services exclusively. The non-real time new call may be assigned only to the NRk 320 channel which dedicatedly receives the non real time service.

The real-time handoff call may be assigned to an Rk 310 channel that accepts real-time services exclusively and an Sk 330 channel that commonly accepts real-time and non-real-time services. The non-real time handoff call may be assigned to an NRk 320 channel dedicated to accepting non real time services and an Sk 330 channel for both real time and non real time services.

The reserved channel 340 is used only for the second vertical handoff call originating in the WLAN, leaving a portion of the NRk 320 which is a shared channel. The reserved channel 340 is dynamically allocated and its amount can be adjusted.

The standby buffer 250 uses a finite buffer to prevent service interruption of the non-real time handoff call.

4 is a flowchart according to an embodiment of the present invention call control method.

4 is a flowchart of a call control method, in particular, taking into account fairness between adjacent cells or between services.

Referring to FIG. 4, the QoS calculator 210 periodically changes traffic of the 3G communication network 30, available bandwidth, service availability, delay time, real-time and non-real-time quality of service, and call blocking rate every time window. The QoS value is calculated using the parameter S (S410). The QoS calculator 210 transmits the calculated QoS value to the time window controller 220.

The time window controller 220 determines whether the QoS value affects a predetermined QoS prescribed value (S420). In this case, the QoS may be a value obtained by measuring a quality of service or the like in a call request to the 3G communication network 30 of the mobile terminal 20. In this case, if the quality of service for the call request reaches the QoS rule, general control is performed on the call request.

If the QoS value does not reach the QoS prescribed value, the time window controller 220 determines whether the call blocking rate exceeds a predetermined call blocking rate prescribed value (S430). If the call block rate exceeds the call block rate prescribed value, the time window controller 220 sets the next time window as a vertical time window (S440). If a call request occurs during a vertical time window, the call control unit 230 makes a first vertical handoff to the call request.

As described above, there are calls for real-time and non-real-time services, and new and handoff calls. The time window controller 220 determines whether an average call blocking rate for real-time and non-real-time services exceeds a prescribed value or a call blocking rate for a handoff call exceeds a prescribed value. If the call block rate exceeds the specified value, it means that the quality of service for the call request is not good. Therefore, if the call blocking rate exceeds the prescribed value, the call blocking rate can be lowered through the vertical handoff, and the QoS can be increased.

If the vertical time window is set, the call controller 230 executes resource management in preparation for the second vertical handoff call of the first vertical handoff call (S450). Resource management for the second vertical handoff call increases the reserve channel 340 in the channel control module 240. The reservation channel 340 may be dynamically changed, so that the channel control module 240 may increase the amount in proportion to the first vertical handoff call.

The reserved channel 340 is preferably located in the Sk 340 channel which is a common channel. Since the second vertical handoff call includes both real-time and non-real-time services, it is efficient to manage them collectively on a common channel that can accommodate both real-time and non-real-time services.

5 is a flowchart of another embodiment of the call control method according to the present invention. See FIGS. 1 to 4.

Referring to FIG. 5, the QoS calculator 210 periodically changes traffic of the 3G communication network 30, available bandwidth, service availability, delay time, real-time and non-real-time quality of service, and call blocking rate every time window. A QoS value is calculated using the parameter of S510. The QoS calculator 210 transmits the calculated QoS value to the time window controller 220.

The time window controller 220 determines whether the QoS value affects the QoS prescribed value (S520). If the QoS value does not reach the QoS prescribed value, the time window controller 220 determines whether a call blocking rate between adjacent cells exceeds a preset neighbor cell defined value (S530). The main cause of hot spot cells is that multiple handoffs are requested in adjacent cells. The basic method for preventing hotspot cells in a wireless network is to reduce the handoff rate of neighboring cells or hotspot cells. If the call blocking rate between neighboring cells exceeds the prescribed value, the first vertical handoff may be performed through the WLAN to maintain fairness between neighboring cells. In addition, if the call blocking rate exceeds the prescribed value, the call blocking rate can be lowered through the vertical handoff, and the QoS can be increased. Here, the call block rate between adjacent cells can be quantified by the average block rate.

The time window controller 220 sets the next time window as a vertical time window when the call blocking rate between adjacent cells exceeds a neighbor cell prescribed value (S550). If a call request occurs during a vertical time window, the call control unit 230 makes a first vertical handoff to the call request.

If it is set as the vertical time window, the call controller 230 executes resource management in preparation for the second vertical handoff call of the first vertical handoff call (S560). Resource management for the second vertical handoff call increases the reserve channel 340 in the channel control module 240. The reservation channel 340 may be dynamically changed, so that the channel control module 240 may increase the amount in proportion to the first vertical handoff call.

The reserved channel 340 is preferably located in the Sk 340 channel which is a common channel. Since the second vertical handoff call includes both real-time and non-real-time services, it is efficient to manage them collectively on a common channel that can accommodate both real-time and non-real-time services.

The time window controller 220 determines whether the call blocking rate between services exceeds a predetermined service prescribed value when the call blocking rate between adjacent cells does not exceed the adjacent cell prescribed value (S540). If the call blocking rate between services exceeds the service threshold, the next time window is set as a vertical time window (S550). If it is set as the vertical time window, the call controller 230 executes resource management in preparation for the second vertical handoff call of the first vertical handoff call (S560).

If the inter-service call blocking rate does not exceed the service threshold, the call controller 230 causes the channel control module 240 to adjust the channel. The channel control module 240 increases an available channel of a service having a relatively high call blocking rate among channels related to each service, and decreases one available channel of a service having a relatively low call blocking rate (S570). This resource management enables fair call control between services.

6 is a flowchart illustrating an embodiment of a call control method when a call is requested.

Referring to FIG. 6, as a call control method for a call request, particularly a new call request, a new call is requested to the 3G communication network 30 (S610).

The call controller 230 determines whether the current time window is a vertical time window or a general time window (S620). If it is the vertical time window, the call controller 230 may lower the call blocking rate by performing a first vertical handoff (S625).

If it is a normal time window, the call controller 230 determines which service a new call request is for (S630). If a new call request for the real-time service, the call controller 230 determines whether there is an available channel in the real-time channel (Rk) 310 (S640). If there is an available channel, the call controller 230 allocates a new call to the corresponding channel (S660) and accepts the new call (S670).

If there is no available channel in the real time channel, the call controller 230 blocks the call reject, that is, the call (S680).

If the new call is a call request for the NRT service, the call controller 230 determines whether there is an available channel in the NRT 320 (S650). If there is an available channel, call control unit 230 allocates a new non-real-time call to the channel (S660), and accepts the call (S670).

If there is no available channel in the non-real-time channel, the call controller 230 blocks the call reject, that is, the call (S680).

7 is a flowchart illustrating another embodiment according to a call control method when a call is requested.

Referring to FIG. 7, as a call control method for a call request, in particular, a handoff call request, a handoff call is requested to the 3G communication network 30 (S710).

The call controller 230 determines whether the current time window is a vertical time window or a general time window (S720). If it is the vertical time window, the call controller 230 may lower the call blocking rate by performing a first vertical handoff (S725). Accordingly, even if a handoff occurs during the movement and the wireless network resource is insufficient, the communication service can be continuously provided to the mobile terminal through the first vertical handoff.

If it is a normal time window, the call controller 230 determines which handoff call request for which service (S730). If the call controller 230 requests a handoff call for the real-time service, the call controller 230 first determines whether there is an available channel in the real-time channel (Rk) 310 (S740). If there is an available channel, the call controller 230 allocates a handoff call to the corresponding channel (S770) and accepts the handoff call (S775). If there is no available channel in the real-time channel (Rk) 310, the call controller 230 determines whether there is an available channel in the common channel (Sk) 330 (S745). If there is no available channel in the common channel (Sk) 330, the call controller 230 blocks the call, that is, blocks the call (S790). (S770) and accept the handoff call (S775).

If the handoff call is a call request for the non-real time service, the call controller 230 determines whether there is an available channel in the non-real time channel (NRk) 320 (S750). If there is an available channel in the non-real time channel (NRk) 320, the call controller 230 allocates a non-real time handoff call to the corresponding channel (S770) and accepts the call (S775).

If there is no available channel in the non-real-time channel, the call controller 230 determines whether there is an available channel in the common channel (Sk) 330 (S755). If there is an available channel in the common channel (Sk) 330, the call controller 230 allocates a non-real time handoff call to the corresponding channel (S770), and accepts the call (S775).

If there is no available channel in the shared channel (Sk) 330, the call controller 230 determines whether there is an available space in the standby buffer 250 (S760). If there is an available space in the standby buffer 250, the call controller 230 stores the non-real time handoff call 250 (S765). When a free channel is generated in a non-real time channel or a shared channel and stored in a buffer, the channel can be allocated and the call is accepted to prevent blocking of the non-real time handoff call as much as possible. The wait buffer 250 may reject the call after a certain period of time. This is to prevent a long delay of a service state that does not allocate a channel and a service delay that does not call rejection.

If there is no available space in the wait buffer 250, the call controller 230 rejects the call, or blocks the call (S790).

The present invention can also be embodied as computer readable code on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disks, optical data storage devices, and the like, which are also implemented in the form of carrier waves (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable code is stored and executed in a distributed fashion. And functional programs, codes and code segments for implementing the present invention can be easily inferred by programmers in the art to which the present invention belongs.

In addition, although the preferred embodiment of the present invention has been shown and described above, the present invention is not limited to the specific embodiments described above, but the technical field to which the invention belongs without departing from the spirit of the invention claimed in the claims. Of course, various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

1 is a schematic diagram of a communication network system including a call control device according to the present invention;

2 is a block diagram of the internal structure of the call control device 10 according to an embodiment of the present invention;

3 is a diagram illustrating a call characteristic model of a cell in an integrated network;

4 is a flowchart according to an embodiment of the present invention call control method;

5 is a flowchart of another embodiment of the call control method according to the present invention;

6 is a flowchart of an embodiment according to a call control method when a call is requested, and

7 is a flowchart illustrating another embodiment according to a call control method when a call is requested.

Explanation of symbols on the main parts of the drawings

10: call control device 210: QoS calculation unit

220: time window control unit 240: channel control module

Claims (17)

A call control method for a call request from a control station of a first wireless network performing data communication with a mobile terminal, Calculating a quality of service (QoS) and a call blocking rate of the first wireless network periodically every time window; Setting a next time window to either a normal time window or a vertical time window based on the QoS and the call block rate; And Performing a first vertical handoff of the call to the second wireless network when receiving a call request from a mobile terminal capable of data communication with a second wireless network that is heterogeneous with the first wireless network during the time window set as the vertical time window. Call control method comprising a. The method of claim 1, If the first vertical handoff is performed, Increasing the amount of dynamic reserved channels for a call making a second vertical handoff from the second wireless network to the first wireless network corresponding to the first vertical handoff. The method of claim 2, The dynamic reservation channel is a call control method, characterized in that the common channel for the real-time and non-real-time service for the public. The method of claim 1, The measured QoS in the time window is less than the preset reference QoS And setting the next time window of the time window as a vertical time window when the call blocking rate exceeds a predetermined call blocking rate prescribed value. The method of claim 4, wherein The call blocking rate is a call blocking rate for a call request of neighbor cells. The method of claim 4, wherein The call blocking rate is a call blocking rate between services for call requests for real-time and non-real-time services. The method of claim 6, When the call blocking rate between the services is below the prescribed value, Increase the available channel of a service having a relatively high call blocking rate among the services by a certain amount, Reducing the available channel of a service having a relatively low call block rate by the predetermined amount. The method of claim 1, If the call request is a new call request for a new call request during a time window for which no vertical handoff is performed, Determining whether the new call request is a call request for a real-time service or a non-real-time service and assigning the new call to an available channel of a channel that accepts the service. The method of claim 1, If the call request is a handoff call request requesting a handoff for a time window during which no vertical handoff was performed, If the handoff call request is a call request for a real-time service, the call further comprises assigning the handoff call to an available channel of a real-time channel that accepts real-time service and a common channel that accommodates both real-time and non-real-time services. Control method. The method of claim 1, If the call request is a handoff call request requesting a handoff for a time window during which no vertical handoff was performed, If the handoff call request is a call request for a non-real-time service, assigning the handoff call to an available channel of a non-real-time channel that accepts the non-real-time service. The method of claim 10, If there is no available channel in the non-real-time channel, Allocating the handoff call to an available channel of a common channel that accepts both real-time and non-real-time services. The method of claim 11, If there is no available channel in the shared channel, Determining whether storage space remains in a standby buffer to prevent blocking of a handoff call for a non-real-time service; And Storing the handoff call in the wait buffer if there is storage space left in the wait buffer. The method of claim 12, If there is no storage space in the wait buffer, rejecting the handoff call request. The method of claim 1, The first wireless network may be any one of a mobile communication network, a wireless LAN network, a Wibro network, an ultra wide band (UWB) network, and a satellite communication network. A call control device for a call request of a mobile terminal in a first wireless network performing data communication with the mobile terminal, QoS that periodically calculates a Quality of Service (QoS) with at least one parameter of traffic change, available bandwidth, service availability, quality of real-time and non-real-time services, and call block rate of the first wireless network every time window. A calculator; A time window controller configured to set a next time window as a vertical time window if the QoS falls below a reference QoS; And And a call controller for performing a first vertical handoff to a second wireless network when a call request of a mobile terminal capable of data communication with a second wireless network that is heterogeneous with the first wireless network is performed during the time window. The method of claim 15, When the first vertical handoff is performed, the call control unit determines the amount of the dynamic reservation channel for the call to make the second vertical handoff from the second wireless network to the first wireless network corresponding to the first vertical handoff. Call control device further comprising a channel control module to increase the. The method of claim 15, And the call control unit includes a wait buffer that waits for the call when the call request is a handoff call request for a non real-time service during a general time window rather than the vertical time window, and there is no available channel.

Images