JP2002191064A - Mobile atm network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mobile ATM network system that can warrant real time performance of communication and reduce a wired network resource utilization rate. SOLUTION: A real time call information storage function section 1 stores information denoting that a call is a real time call, a non real time call information storage function section 4 stores information denoting that a call is a non real time call. On the occurrence of a hand-over request from a mobile terminal, when the call is the real time call, a soft hand-over start function section 3 starts soft hand-over and when the call is the non real time call, a hard hand-over start function section 6 starts hard hand-over. Thus, interruption of cell transfer at hand-over of the real time call is prevented so as to nullify delay or delay fluctuations due to the interruption of cell transfer. Furthermore, the wired network utilizing rate at hand-over of the non real time call can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a handover control system in a mobile ATM network system including an ATM switch having a switching function of an ATM communication system, a base station, and a mobile terminal.

[0002]

2. Description of the Related Art A connection establishing operation for a handover in a conventional mobile ATM network system will be described with reference to FIGS. FIG. 3 includes a central control station (11a), a plurality of ATM switches (ae), a base station A, a base station B, a mobile terminal, and a communication partner.
1 shows a system configuration diagram of a conventional mobile ATM network that activates soft handover. Hereinafter, the operation of establishing a connection for handover for soft handover will be described with reference to FIG. In the network of FIG. 3, the handover request message (100) transmitted from the mobile terminal to the central control station (11a) is received by the soft handover activation function unit (13) via the message input / output function unit (10). I do. Upon receiving the handover request message (100), the soft handover activation function unit (13) transmits a soft handover real connection establishment message (121) regardless of whether the call is real-time or non-real-time, and performs soft handover. Start The real connection establishment message for soft handover (121) is transmitted in the order of the ATM switch (a), the ATM switch (b), the ATM switch (d), and the ATM switch (e). As a result, the real connection for soft handover (201a) ~
201b) is established. The real connection for soft handover is a connection through which actual ATM cells flow, in addition to the resource reservation of the ATM switch such as bandwidth reservation.

[0003] By doing so, the mobile terminal can use the AT
Two paths, an M switch (c) -ATM switch (a) -ATM switch (b) path and an ATM switch (e) -ATM switch (d) -ATM switch (b) path, can be used at the time of handover. . Therefore, the handover can be executed without interrupting the communication, the cell transfer is not interrupted at the time of the handover, and the delay and the delay fluctuation due to the interruption of the cell transfer do not occur. However, since communication is performed using a plurality of paths at the same time during handover, there has been a problem that the utilization rate of a wired network during handover increases.

FIG. 4 shows a central control station (11b) and a plurality of As.
FIG. 1 shows a system configuration diagram of a conventional mobile ATM network for initiating hard handover, which includes a TM switch (a to e), a base station A, a base station B, a mobile terminal, and a communication partner. Hereinafter, the operation of establishing a connection for handover for hard handover will be described with reference to FIG. In the network of FIG. 4, the handover request message (100) transmitted from the mobile terminal to the central control station (11b) is received by the hard handover activation function unit (16) via the message input / output function unit (10). I do. Upon receiving the handover request message (100), the hard handover activation function unit (16) determines whether the call is real-time or non-real-time.
A hard handover spare connection establishment message (122) is transmitted to start hard handover. The hard handover spare connection establishment message (122) is transmitted in the order of the ATM switch (a), the ATM switch (b), the ATM switch (d), and the ATM switch (e). As a result, the hard handover spare connection (202a) To 202b) are established. The spare connection for hard handover is a connection in which only ATM switch resources such as bandwidth reservation are reserved and actual ATM cells do not flow.

[0005] By doing so, the mobile terminal communicates on the ATM switch (c) -ATM switch (a) -ATM switch (b) path before the handover, and after the handover, the ATM switch (e) -ATM switch. (D)-Communication can be performed via the path of the ATM switch (b). Since communication can be performed without using a plurality of paths at the time of handover, the wired network utilization rate at the time of handover does not become higher than when using a plurality of paths at the same time. However, since communication is interrupted in order to switch the path at the time of handover, there is a problem that cell transfer is interrupted at the time of handover, and delay and delay fluctuation due to cell transfer interruption occur.

[0006]

As described above, in the conventional mobile ATM network system, the handover of a system uniquely determined in the mobile ATM network system without distinguishing between a real-time call and a non-real-time call. Had started. Therefore, when a hard handover is activated for a real-time call, there is a problem that cell transfer is interrupted at the time of handover, and delay and delay fluctuation due to cell transfer interruption occur. In addition, when soft handover is started for both real-time calls and non-real-time calls, communication is performed using multiple paths at the same time during handover, and the wired network utilization rate during handover increases. there were.

Accordingly, an object of the present invention is to provide a mobile ATM
In a network system, it is an object of the present invention to perform handover capable of guaranteeing real-time communication and reducing the utilization rate of a wired network resource.

[0008]

In order to solve the above-mentioned problems, a first mobile ATM network system of the present invention comprises a real-time call information holding function unit (1) for holding information indicating that a call is in real time. A real-time call determination function unit (2) for determining whether a call is real-time based on information held in the real-time call information storage function unit (1); and a real-time call determination function unit (2). A soft handover activation function unit (3) for activating a soft handover for a call determined to be present is provided, and when a handover request occurs, the soft handover is activated if the call is in real time. Things. Thus, when a handover request is issued from the mobile terminal, the result of determining whether the call is real-time is checked, and in the case of real-time, a soft handover is activated to prevent interruption of cell transfer at the time of handover of the real-time call. However, delay and delay fluctuation due to cell transfer interruption can be reduced to zero.

The second mobile ATM network system of the present invention further comprises a non-real-time call information holding function unit (4) for holding information indicating that the call is non-real-time, and the non-real-time call information holding function unit. The non-real-time call determination function unit (5) for determining whether the call is non-real-time based on the information held in (4), and the non-real-time call determination function unit (5) determines that the call is non-real time. A hard handover activation function unit (6) for activating a hard handover for a call that has been made,
When the call is non-real time, a hard handover is activated. Thus, when a handover request is issued from the mobile terminal, the result of determining whether the call is non-real-time is determined, and in the case of non-real-time, a hard handover is activated, thereby enabling a wired network during non-real-time call handover. The utilization rate can be reduced.

[0010]

FIG. 1 is a diagram showing an example of a system configuration of a mobile ATM network system according to the present invention. This network system comprises a central control station (11).
And a plurality of ATM switches (a to e), a base station A, a base station B, a mobile terminal, and a communication partner. In this figure, a mobile terminal communicates with a communication partner terminal via a wired network as a mobile communication backbone while moving. Wired networks are base stations A, B, AT
It comprises M switches (a to e) and a central control station (11). The centralized control station 11 performs centralized control of rerouting during soft and hard handover, remote control of connection establishment and path switching, and the like.

Also, all ATM switches (a to e)
Has a built-in control platform common to hard handover and soft handover, and performs processing corresponding to each handover in response to a signaling message from the central control station (11). That is, at the time of executing the hard handover, the ATM switch serving as a branch point between the path before the handover and the path after the handover has a cell preservation (cell preservation) on its input buffer side.
ion) operation to temporarily stop cell transfer. Next, after the completion of the path switching, a cell release operation for flowing the accumulated cells is performed. On the other hand, when executing a soft handover, the ATM switch, which is a branch point between the route to one base station and the route to another base station, creates a copy based on the cell arriving at the input buffer side, and creates a copy of the original and the copy In addition to performing a cell replication operation for flowing cells, a cell fusion operation for synchronizing a plurality of cells arriving from different ports and selecting and flowing a cell having a better reception state or the like is performed.

First, a handover connection establishment operation in the first embodiment of the mobile ATM network system of the present invention for activating soft handover in response to a handover request of a real-time call will be described.
This will be described with reference to FIG. In the network of FIG.
When a call is established between a mobile terminal and a communication partner, the real-time call information holding function unit (1) of the central control station (11) determines whether the call is real-time or non-real-time. (50) is saved.
As this information, for example, information on the QoS class of the call can be used. The real-time call determination function unit (2) determines whether the call is real-time based on the real-time call information (50), and uses the result as a real-time call determination result (51). Output to (3). These processes are performed in advance before a handover occurs. For example, it may be performed when a call is established.

A handover request message (100) transmitted from the mobile terminal to the central control station (11) when the mobile terminal moves across a cell or the like is transmitted via the message input / output function unit (10). Received by the soft handover activation function unit (3). At this time, the hard handover activation function unit (6) also receives the handover request message (100) from the message input / output function unit (10) at the same time. The operation of the hard handover activation function unit (6) is described below. It will be described later with reference to FIG. The soft handover activation function unit (3), which has received the handover request message (100), sees the real-time call determination result (51) already output from the real-time call determination function unit (2), and determines that the call is in real time. Check if it is. That is, it is determined whether or not the call identification number included in the handover request message (100) is included in the real-time call determination result (51).

As a result, if the call is a real-time call, the soft handover activation function unit (3) issues an actual connection establishment message for soft handover (121).
To initiate soft handover. Real connection establishment message for soft handover (121)
Has a list of ATM switches to which the message is to be transmitted, information on the call such as a band used by the call, and information such as designation of an ATM switch for performing cell duplication and cell fusion. According to the list, the real connection establishment message (121) for soft handover is transmitted in the order of the ATM switch (a), the ATM switch (b), the ATM switch (d), and the ATM switch (e). Then, according to the information about the call, such as the band used by the call,
ATM switch resource reservation such as bandwidth reservation used by the call is performed by the ATM switch (b), ATM switch (d), and AT.
This is performed for the M switch (e). Further, cell replication and cell fusion are performed in the ATM switch (b), which is a branch point between the path before handover and the path after handover, according to the information specified by the ATM switch that performs cell replication and cell fusion. As a result, a real connection for soft handover (201a to 201b) is established. The actual connection for soft handover is defined as A such as bandwidth reservation.
This is a connection that not only reserves resources for the TM switch but also flows actual ATM cells.

[0015] By doing so, the mobile terminal can access the AT
Two paths, an M switch (c) -ATM switch (a) -ATM switch (b) path and an ATM switch (e) -ATM switch (d) -ATM switch (b) path, can be used at the time of handover. . Therefore, handover can be performed without interrupting communication for a real-time call, and cell transfer interruption during handover does not occur.
No delay or delay fluctuation due to cell transfer interruption occurs for a real-time call. On the other hand, since communication is performed by simultaneously using a plurality of paths at the time of handover only for a real-time call, the wired network utilization rate at the time of handover is lower than when soft handover is always activated.

Next, a handover connection establishing operation in the second embodiment of the mobile ATM network system according to the present invention for activating a hard handover in response to a handover request for a non-real-time call will be described with reference to FIG. . FIG. 2 shows a central control station (1
FIG. 1 is a system configuration diagram of a mobile ATM network according to an example of the present invention for initiating a hard handover, including a 1), a plurality of ATM switches (a to e), a base station A, a base station B, a mobile terminal, and a communication partner Has the same configuration as the system configuration diagram shown in FIG.

In the network of FIG. 2, when a call is established between a mobile terminal and a communication partner, a central control station (11)
The non-real-time call information holding function unit (4) stores non-real-time call information (60) that is used to determine whether the call is real-time or non-real-time. As this information, information on the QoS class of the call can be used as described above. Then, the non-real-time call determination function unit (5) outputs the non-real-time call information (6).
Based on (0), it is determined whether the call is non-real-time, and the result is output to the hard handover activation function unit (6) as a non-real-time call determination result (61).
These are performed before the handover occurs (for example, when a call is established).

The handover request message (100) transmitted from the mobile terminal to the central control station (11) is received by the hard handover activation function unit (6) via the message input / output function unit (10). Upon receiving the handover request message (100), the hard handover activation function unit (6) sees the non-real-time call determination result (61) already output from the non-real-time call determination function unit (5), and determines that the call has not been made. Check if it is real time. This corresponds to the handover request message (10
The determination is made based on whether or not the identification number of the call included in 0) is included in the non-real-time call determination result (61).

As a result, if the call is non-real time, the hard handover start-up function unit (6) sends a hard handover backup connection establishment message (12).
Send 2) to initiate hard handover. Hard handover spare connection establishment message (1
22) has a list of ATM switches to which the message is to be transmitted and information on the call such as a band used by the call. According to the list, the spare connection establishment message for hard handover (122) is transmitted in the order of the ATM switch (a), the ATM switch (b), the ATM switch (d), and the ATM switch (e). Then, according to information about the call, such as the band used by the call,
ATM switch resource reservation such as bandwidth reservation used by the call is performed by ATM switch (b), ATM switch (d), and AT switch.
This is performed for the M switch (e). As a result, the hard handover spare connection (202a-202)
b) is established. The spare connection for hard handover is a connection in which only ATM switch resources such as bandwidth reservation are reserved and actual ATM cells do not flow. By the way, information such as designation of an ATM switch that performs cell storage and cell release is provided by a hard handover spare connection establishment message (1).
The message is transmitted by another message transmitted at a timing later than 22), and according to the other message, the ATM switch (b) serving as a branch point between the path before the handover and the path after the handover stores and releases the cell. Will be performed.

By doing so, the mobile terminal communicates on the ATM switch (c) -ATM switch (a) -ATM switch (b) path before the handover, and after the handover, the ATM switch (e) -ATM switch. (D)-Communication can be performed via the path of the ATM switch (b). Since communication can be performed without using a plurality of paths at the time of handover, the wired network utilization rate at the time of handover does not become higher than when using a plurality of paths at the same time. On the other hand, since communication is interrupted at the time of handover only for non-real-time calls,
Delay or delay fluctuation due to cell transfer interruption occurs only for non-real-time calls. In general, non-real-time calls are not guaranteed for delay or delay fluctuation, so even if they become large, for example, about one second, there is no significant problem.

As described above, when a handover request is issued from a mobile terminal, if the request is a real-time call, a soft handover is activated to prevent interruption of cell transfer at the time of handover of a real-time call. Delay and delay fluctuation can be set to zero. Further, when a handover request is issued from the mobile terminal, if the request is a non-real-time call, by activating a hard handover, it is possible to reduce the wired network utilization rate during the handover of the non-real-time call.

In FIGS. 1 and 2, the real-time call information holding function unit (1) and the non-real-time call information holding function unit (4) are provided independently. An information holding function unit may be provided. The real-time call determining function unit (2) and the non-real-time call determining function unit (5) are also provided with a unified function and a determining function unit for determining whether the call is a real-time call or a non-real-time call. It may be. Further, in the above-described embodiment, the real-time call determination result (51) and the non-real-time call determination result (61) are output in advance to the soft handover activation function unit (3) and the hard handover activation function unit (6), respectively. However, the present invention is not limited to this, and a database storing determination result information as to whether the call is a real-time call or a non-real-time call is provided, and the soft handover activation function unit is provided. (3) and the hard handover activation function unit (6) executes the handover request message (10
When (0) is received, the operation may be determined with reference to the database.

[0023]

As described above, the mobile ATM of the present invention is
According to the network system, when a handover request is issued from a mobile terminal, the result of judging whether the call is real-time or not is activated in the case of real-time. There is an effect that interruption can be prevented and delay and delay fluctuation due to interruption of cell transfer can be reduced to zero.
Also, when a handover request is issued from a mobile terminal,
Looking at the result of determining whether the call is non-real-time, in the case of non-real-time, activating the hard handover has the effect of reducing the wired network utilization rate during the non-real-time call handover.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of an embodiment of a mobile ATM network of the present invention.

FIG. 2 is a system configuration diagram of another embodiment of the mobile ATM network of one example of the present invention.

FIG. 3 is a system configuration diagram of a conventional mobile ATM network.

FIG. 4 is a system configuration diagram of another conventional mobile ATM network.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Real-time call information holding function part 2 Real-time call judgment function part 3 Soft handover starting function part 4 Non-real-time call information holding function part 5 Non-real-time call judgment function part 6 Hard handover starting function part 10 Message input / output function part 11 Central control station a to e ATM switch A, B base station

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5K030 HA10 HC09 KA03 LB01 LB09 LB19 5K051 AA02 BB02 CC07 DD09 DD15 EE01 FF02 FF11 FF16 5K067 AA15 AA33 BB02 DD36 DD43 DD57 EE02 EE10 EE16 EE24 HH11 JJ39

Claims (2)

[Claims] 1. A real-time call information holding function unit for holding information indicating that a call is real-time, and a real-time determining whether the call is real-time based on the information held by the real-time call information holding function unit. A call determination function unit; and a soft handover activation function unit for activating a soft handover for a call determined to be real-time by the real-time call determination function unit. A mobile ATM network system characterized by activating soft handover in case of (1). 2. A non-real-time call information holding function unit for holding information indicating that a call is non-real-time, and whether the call is non-real-time based on the information held by the non-real-time call information holding function unit. A non-real-time call determination function unit for determining whether a call is determined to be non-real-time by the non-real-time call determination function unit. A mobile ATM network system characterized by activating a hard handover when the call is non-real-time.