JP2003111135A - Congestion control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a congestion control system that enables more user terminals to get into communication by suppressing a further increase in traffic when traffic increases to a certain degree. SOLUTION: When a D-RNC 122 detects congestion (step S61), the D-RNC 122 searches a table for DCH that can reduce the number of radio links 15 (step S62). Then the D-RNC 122 notifies the corresponding S-RNC 12 of the DCH. Upon receiving the notice, the S-RNC 12 examines the reduction of the number of radio links 15 and requests a mobile communication exchange 11 to correct the number of radio links 15. When the exchange 11 accepts the request, the traffic of the D-RNC 122 can be reduced. When the congestion is significant, the informed S-RNC 12 can also delete the corresponding radio link 15 itself.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a congestion control system which, when a slight congestion occurs in a wireless network control device which communicates wirelessly with a mobile terminal, prevents the state from further deteriorating or improves the state.

[0002]

2. Description of the Related Art FIG. 4 shows an outline of a communication system for mobile terminals. Mobile switching center (MM
S) 11 is a plurality of wireless network control devices 12 ₁ , 1
2 ₂ connected to nodes 13 ₁₁ and 13 ₁₂ respectively.
Or nodes 13 _21, 13 ₂₂ via the user terminal (U
E (User End) 14 ₁ , 14 ₂ wireless communication is realized. In the figure, each curve shows radio links 15 ₁ to 15 ₃ as links for three wireless sections for the first user terminal 14 ₁ to communicate with a terminal not shown.

Here, the first and second user terminals 1
Four₁, 14₂Is a mobile phone, for example, the node
Thirteen_{twenty one}, 13_{twenty two}Corresponds to a wireless base station. Mobile communication exchange
Although the station 11 is not shown in the figure, it is connected to a normal telephone line network.
Through this, the user terminal 14 ₁, 14₂Is not shown
You can also talk to fixed-line phones.

In such a communication system, for example, the first
It is assumed that the user terminal 14 ₁ has registered its location and started communication in the communication area (cell) of the node 13 ₁₁ . At this time, the first network control device 12 ₁ is treated as a device that handles the billing information of the _first user terminal 14 ₁ . Such a network controller 12 is generally an S-RNC.
It is called (Serving-Radio Network Controller).

After the communication using the first network controller 12 ₁ is started, the first user terminal 14 ₁ moves to the arrow 15
It is assumed that the soft handover is performed by moving from the communication area of the node 13 ₁₁ to the node 13 ₂₁ under the jurisdiction of the _second network control device 12 ₂ as shown in FIG.
A device such as the second network control device 12 ₂ having jurisdiction over the destination node 13 ₂₁ or the like is generally a D-RNC (Dri
fting-Radio Network Controller). If the first user terminal 14 ₁ moves, the D-RNC will be changed accordingly, but the S-RNC is a device that has registered the location of the first user terminal 14 ₁ , and billing information, etc. The change is not made due to the need to manage the. Therefore, even if the first user terminal 14 ₁ is moved to any position in the communication, the radio link 15 as shown in FIG. 4 ₁
˜15 ₃ always goes through the _first network control device 12 ₁ .

By the way, the node 1 under the control of the second network controller 12 _{2 to which} the first user terminal 14 ₁ moves
When the traffic of 3 ₂₁ or the node 13 ₂₂ is high, it becomes difficult to perform soft handover from another node 13 ₁₁ . Also, these nodes 13 ₂₁ ,
Another user terminal 1 (not shown) from the calling area 13 ₂₂
Even if 4 tries to make a call, it becomes difficult for the call to be set up. Therefore, measures for improving such traffic have been considered.

FIG. 5 shows a processing sequence when a soft handover is performed when congestion occurs in the conventionally proposed congestion control system. When performing a soft handover, the S-RNC (first network controller) 12 ₁ is connected to the D-RNC (second network controller) 12 ₂ by a radio
Link setup (Radio Link Setup) is performed (step S21). In D-RNC 12 ₂ side at this time and is generating congestion 31 high traffic. Then, the D-RNC12 ₂ side sends a signal (Failure) indicating that link setting has failed together with the cause (Cause) to the S-R.
Notify the NC 12 ₁ (step S22).

[0008] Then, in the S-RNC 12 ₁ side by using the timer (not shown) to reset the timing setup (step S23). Then, after the predetermined time has elapsed, set the radio link setup again to D-RNC1.
22. Attempt to perform on the 2 ₂ side (step S24).
If resolved congestion in D-RNC 12 ₂ side at this time, soft handover is realized. When that is not right, the process of step S22 will be performed and timing will be taken again.

However, the congestion control system as shown in FIG.
In the stem, the D-RNC12 is actually ₂Traffic on the side
Soft handoff when the value becomes unacceptably high
I try to limit the number of servers. Therefore, the congestion state
There is no choice but to wait for the link setting until the problem disappears. others
Therefore, the user terminal 14 on the move₁Is the place where you cannot talk
There was an inconvenience. Also, the node 13_{twenty one}
Or node 13_{twenty two}Existing in the call area of
Congestion is resolved in the other user terminals 14 that are not talking
Problem that you cannot start a call until
was there.

The above is 3GPP (The Third Generation)
It is being considered at the stage of creating specifications for a third-generation mobile communication system called Partnership Project, and part of the procedure is ITU (International Telecommunicatio).
n Union: International Telecommunication Union) and has been recommended as IMT2000.

In view of this, in Japanese Unexamined Patent Publication No. 8-65338, when congestion occurs, notification is given to an adjacent switching node or terminal to control the line speed to suppress an increase in unnecessary traffic. I have to.

FIG. 6 shows the structure of a frame relay terminal in the proposed congestion control system. The frame relay switching node has the same configuration. The frame relay terminal 41 includes a negotiation frame creation unit 42, a line speed control unit 43, and a frame input / output unit 44 connected to these. The frame input / output unit 44 is connected to the line 45.

According to this proposal, two or more terminals are connected via one or two or more switching nodes to form a network for transferring information in units of frames of a predetermined format. Then, when congestion occurs, the congestion notification is given to the frame relay terminal 41 and the like shown in FIG. Frame relay terminal 41 that received the congestion notification
In the negotiation frame creating unit 42, the negotiation frame creating unit 42 creates a negotiation frame for performing negotiation regarding a change in line speed. Through this negotiation, the line speed control unit 43 controls to increase or decrease the line speed with the adjacent transfer destination terminal or switching node (both not shown). That is, the line speed control unit 43 of the frame relay terminal 41 reduces the speed of the line into which the frame flows into the switching node having the congestion. On the contrary, if the frame relay terminal 41 is on the side where the frame flows in from the switching node, the line speed is increased to increase the ratio of the frames flowing out from the switching node. In this way traffic is reduced.

Further, in the proposal disclosed in Japanese Patent Laid-Open No. 22407/1993, a congestion exchange serving as an exchange that has detected congestion uses a signal of a common line signaling system or the like as the originating exchange as the originating exchange. I am trying to notify you of this.
Upon receiving this notification, the originating exchange starts control for changing the call restriction amount and limits the target for continuing the call processing. The congestion exchange also reduces the traffic by changing the restriction amount of the incoming call by feedback control.

[0015]

However, in the proposal disclosed in Japanese Unexamined Patent Publication No. 8-65338, since the traffic of a specific switching node is reduced by changing the line speed, it is possible to change the line speed. Otherwise, this technology cannot be applied. In addition, JP-A-5
According to the proposal disclosed in Japanese Patent Laid-Open No. 22407/1994, since the call regulation amount is changed, a person who has already made a call has a problem that the call cannot be made due to the call restriction.

Therefore, an object of the present invention is to suppress the further increase when the traffic increases to some extent,
It is to provide a congestion control system that enables more user terminals to communicate.

[0017]

In a congestion control system according to claim 1, (a) a plurality of mobile terminals that perform wireless communication, and (b) a mobile terminal that sets links for communication between these mobile terminals. (C) A maximum of a plurality of links is formed between the same transmission / reception with each of the mobile switching center and (c) each of the mobile terminals that are subordinate to this mobile switching center and to which wireless communication is allocated from the mobile communication switching center, and wirelessly form a maximum of (D) a plurality of wireless network control devices each having a communication means for performing communication and a traffic detection means for detecting the traffic state from the ratio of the number of links to the allowable total number; When the traffic detecting means detects traffic of a predetermined value or more, the control device sends a packet from another wireless network control device via the mobile switching center. The link number reduction request means for requesting the mobile terminal having set the number to reduce the number of a plurality of links set between the same transmission / reception, and the link number reduction request means of another radio network controller It further comprises link number reduction executing means for executing the reduction when requested to reduce the number.

That is, according to the first aspect of the present invention, mobile terminals, a mobile communication switching center that establishes links for communication between these mobile terminals, and a wireless network arranged between the mobile terminals and the mobile communication switching center. In the communication system including the control device, the traffic detection means of the wireless network control device detects when traffic of a predetermined value or more,
A request is made from another wireless network control device to a mobile terminal having a path set via the mobile communication switching center to reduce the number of a plurality of links set for the same transmission and reception. Similarly, when the link number reduction requesting means of another wireless network control device requests reduction of the link number, the link number reduction executing means reduces the number of links so as to meet this request. . As described above, since the wireless network control device is provided with the link number reduction requesting means on the side requesting the traffic adjustment and the link number reducing execution means on the side requested to adjust the traffic, whether it functions as an S-RNC or not. -R
Regardless of whether it functions as an NC, when traffic increases to some extent, it is possible to control congestion so that more user terminals can communicate while suppressing further increase.

According to the second aspect of the present invention, (a) traffic detecting means for detecting a traffic state of each wireless network control device, and (b) when the traffic detecting means detects traffic of a predetermined value or more. , A specific mobile terminal that determines a mobile terminal that has moved by a soft handover from a wireless network control device other than the wireless network control device that has detected the communication, and that has multiple links for wireless communication between the same transmission and reception A determining means; (c) a link number reduction requesting means for requesting the mobile terminal discriminated by the specific mobile terminal discriminating means to reduce the number of links; Link number reduction execution means for reducing the reduction when requested,
(E) When this link number reduction executing means reduces the number of links, the number of links is reduced to the devices existing on the path from the radio network controller to the link number reduction requesting means that has requested the reduction of the number of links. The congestion control system is provided with a link number reduction notifying means for notifying the.

That is, according to the second aspect of the present invention, the traffic detecting means detects the traffic state of each wireless network control device, and when the detected value is equal to or more than a predetermined value, the specific mobile terminal discriminating means detects it. A mobile terminal that has moved by a soft handover from a wireless network control device other than the wireless network control device that has performed the above-mentioned is determined to have a plurality of links for wireless communication between the same transmission and reception.
In order to reduce the total number of links, the link number reduction requesting means requests the mobile terminal discriminated by the specific mobile terminal discriminating means to reduce the link number. This is because a plurality of links for wireless communication are provided between the same transmission / reception, and communication is possible even if some of these links are lost, so that the number of these links can be reduced. In response to this request, the link number reduction executing means reduces the number of links to reduce the traffic. However, by notifying the relevant path in advance that the number of links will be reduced, the occurrence of a failure due to this will occur. To prevent.

According to a third aspect of the invention, in the congestion control system according to the first or second aspect, the link number reduction executing means reduces the number of links of mobile terminals having low priority.

That is, in the invention according to claim 3, the link number reduction executing means reduces the number of links in which low-priority communication is performed, so that communication having high priority is not affected as much as possible. .

According to a fourth aspect of the present invention, in the congestion control system according to the third aspect, the link number reduction executing means disconnects all the links to one mobile terminal when the request is not satisfied due to the reduction of the link number. I am trying.

That is, in the invention according to claim 4, the link number reduction executing means discards the method of leaving at least one link from a plurality of links for one mobile terminal when the traffic problem cannot be solved by the reduction of the number of links. ,
I'm going to disconnect all links. Also at this time, it is effective to disconnect the link with the link having the lower priority first.

According to a fifth aspect of the present invention, in the congestion control system according to the second aspect, the link number reduction notifying means is the wireless network after soft handover is performed from the wireless network control device before soft handover is performed. It is characterized in that this is notified to the mobile switching center which has set a path in the control device.

That is, according to the invention described in claim 5, since it is necessary to notify each device having the link that the number of links is reduced, the mobile switching center in charge is also notified of this. Is shown.

According to a sixth aspect of the present invention, in the congestion control system according to the first or second aspect, the traffic detecting means detects traffic in a plurality of stages and the link number reduction requesting means responds to the link number reduction. It is characterized by making a request.

That is, the invention according to claim 6 indicates that the traffic can be classified into a plurality of stages and a request for reducing the number of links can be made according to these. When the traffic is low, the demand for reducing the number of links is small, and when the traffic is extremely high, disconnection of the entire link may be required. By classifying traffic in multiple stages and handling it in this way, fine-grained control becomes possible.

[0029]

DETAILED DESCRIPTION OF THE INVENTION

[0030]

EXAMPLES The present invention will be described in detail below with reference to examples.

FIG. 1 shows a processing sequence for congestion occurrence in one embodiment of the present invention. In addition,
The overall configuration of the congestion control system in this embodiment is the same as that shown in FIG. Therefore, FIG. 4 is also used in the description of this embodiment.

As a premise of the description of the present embodiment, the first user terminal 14 ₁ is the S-RNC (first
Node 13 ₁₁ under the network control device 12 ₁
It is assumed that communication is started by registering the location in the call area (cell) of. After this, the first user terminal 14 ₁ moves as shown by the solid line in FIG.
-It is assumed that wireless communication is performed using the nodes 13 ₂₁ and 13 ₂₂ under the control of the RNC (second network control device) 12 ₂ . At this time, the first user terminal 14
The _1, three radio link (Radio Link) 15 ₁ ~1
5 ₃ is set. It is assumed that, in principle, three radio links (Radio Link) are set for each of the other user terminals (not shown) in order to secure stable communication. In the figure, the mobile switching center 11 and S
The interface between -RNC12 ₁ is called "iu", and the interface between S-RNC12 ₁ and D-RNC12 ₂ is called "iu". In addition, the interface between the D-RNC 12 ₂ and the nodes 13 ₂₁ and 13 ₂₂ is set to “iu
b ".

[0033] Under such circumstances, D-RNC 12 ₂ as a radio network controller of a destination that has been subjected to the soft handover, detects that a first value or more set in advance for traffic congestion It is assumed that the occurrence of is determined (step S61). D-RNC12
₂ is a DCH (Dedicated Channel: user information) that can reduce the number of the radio links 15 described above at this point.
Search for control information transfer channel) (step S6)
2). Then, S- as a wireless network control device
If RNC12 ₁ corresponds to this, D-RNC1
2 ₂ notifies it of the occurrence of congestion (step S63).

Upon receiving this notification, the S-RNC 12 ₁ considers executing the reduction of the number of radio links 15 ₁ to 15 ₃ for the first user terminal 14 ₁ that has been soft-handed over (step S64). The details of the reduction of the number of radio links 15 ₁ to 15 ₃ are described in detail in a mobile communication switching center (MMS (Mobile Multimedia Switching Cente
r), MSC (Mobile-services Switching Center),
CN (Core Network)) 11 and D-RNC 12 sends to the mobile communication switching center 11 a request for a change to notify ₂ (step S65). Here, it is assumed that this is the content of deleting one of the radio links 15 ₁ to 15 ₃ . When the mobile switching center 11 recognizes this and returns a response, the S-RNC 12 ₁ deletes _one of the radio links 15 ₁ to 15 ₃ .

At this stage, the mobile switching center 11 and D-
The RNC 12 ₂ has been notified of the reduction of the number. Therefore, even if the number of radio links 15 reaching the D-RNC 12 ₂ via the S-RNC 12 ₁ is reduced to the notified content, these devices may erroneously determine that the link reduction is a failure. There is no.

On the D-RNC 12 ₂ side, the number of radio links 15 set through the S-RNC 12 ₁ decreases, so the traffic decreases by this amount. Also, if the occurrence of congestion is similarly notified to other S-RNC 12 not shown in step S63, these S
-RNC12 can through to reduce the number of radio link 15 leading to D-RNC 12 ₂ to. Therefore, if the traffic decreases as planned, the congestion state can be resolved.

In this way, the target S-RNC 12 may avoid the congestion state by reducing the number of radio links 15 respectively, but traffic may not be reduced or may be reduced due to new call setting or the like. May increase. If such a latter improved traffic is not performed, again with D-RNC 12 ₂ side is notified that it is congested. It may be a notification that the traffic has increased and further congestion has occurred.

In such a case, for example, S-RNC12
_{In 1} , the number of radio links 15 should be further reduced by one, or if the communication is of low urgency, it is considered to disconnect all the numbers of radio links 15. And similarly to step S65 described above, the contents, and sends a change request to notify the mobile switching center 11 and D-RNC 12 ₂ to the mobile communication switching center 11.
Then, if a response to this is returned, the number of radio links 15 is further reduced by one at that time, or if the communication is of low urgency, disconnection of all the radio links 15 is performed. .

By performing the above control, the D-RN
On the C12 ₂ side, it is possible to reduce the traffic and eliminate the congestion state. Incidentally, when the line state of the D-RNC 12 ₂ becomes good, the control for increasing the number of radio link 15 to the original value may be made is of course.

FIG. 2 shows D- when the above control is performed.
It specifically shows one example of the flow of processing on the RNC side. The D-RNC 12 ₂ is equipped with a CPU (central processing unit) (not shown) together with the S-RNC 12 ₁ and performs predetermined control using a control program stored in a storage medium (not shown).

[0041] That is D-RNC 12 ₂ is detected traffic for the node 13 _21, 13 ₂₂ under, when it reaches the first H (high) level, such as less than 90 percent, for example 75 percent or more (step S71 : Y), S-RNC1 searching its own table and communicating on multiple radio links 15
2 is picked up (step S72). Then, the D-RNC12 ₂ is the first of these S-RNC12.
Notification that the H level has been reached (step S7)
3).

FIG. 3 shows the control contents on the S-RNC side. S-RNC 12 is either notification sent from the D-RNC 12 ₂ are first H level of one (step S81) traffic, or traffic that a second H-level as when higher and 90 percent or more (step Check S82). If the notification is the first H level notification (step S81: Y), it is determined whether or not the link remains even after one radio link 15 is reduced for the call (step S8).
3). If it remains (Y), the mobile communication switching center (MMS) 1 is required to reduce the radio link 15 by one.
1 is requested (step S84). When a response indicating that the request is recognized is returned (step S85:
Y), one radio link 15 is reduced (step S86). As a result, since the radio link 15 still remains, communication with the corresponding user terminal 14 ₁ such as the _first user terminal 14 ₁ is possible.

On the other hand, D-RNC 12 ₂ Returning to FIG. 2 is not improved for traffic, and its value reaches the second H-level (step S74: Y). In this case, D-RNC 12 ₂ is communicating with a plurality of radio link 15 searches its own table as well S
-Pick up the RNC 12 (step S75).
Then, for these S-RNC12, D-RNC1
2 ₂ notifies that it has reached the second H level (step S76).

In the S-RNC 12, as shown in FIG.
-When the RNC 12 ₂ notifies that the traffic has reached the second H level (step S81: N, step S82: Y), is the target of the radio link 15 high-priority communication or other communication? It is determined whether it is communication (step S87). Here, the high-priority communication refers to communication to a place such as a police station or a fire station that is likely to require an urgency registered in advance. It is possible to treat this as high-priority communication when communication with high billing is performed in advance.

If the target of the radio link 15 is not high priority (N), a request to delete the entire relevant radio link 15 is sent to the mobile communication switching center 11 (step S88). When a response indicating that the request has been recognized is returned (step S89: Y), the entire radio link 15 concerned is reduced (step S90). In this case, the communication of the user terminal such as the corresponding user terminal 14 ₁ cannot be performed.

On the other hand, when the target of the radio link 15 has high priority (step S87: Y), the process proceeds to step S83 and thereafter. That is, multiple radios
If one link 15 is to be reduced, this is requested and executed (step S86). The target of the radio link 15 is high priority, and the radio link 1
If the further deletion of 5 eliminates the link itself and disables communication, the request for link reduction is ignored (end). This is to ensure high-priority communication. In this case also, the traffic can be reduced by the other similar S-RNC 12 deleting the radio link 15 or the like.

Returning to FIG. 2 again, the description of the control of the D-RNC 12 ₂ will be continued. D-RNC12 ₂ is the mobile communication switching center 1
If there is a notification to reduce or delete links from 1 (step S77: Y), the contents of its own table are modified (step S78). As a result, the contents of the table to be searched can be always kept in a new state when the traffic next reaches the first H level or the second H level.

In the embodiment, the traffic or congestion state is specified in two stages, but it goes without saying that it may be one stage or three or more stages. Further, the traffic threshold value is not limited to the value such as 75% as in the embodiment.

[0049]

As described above, the first to sixth aspects of the invention are described.
According to the described invention, the traffic is reduced by reducing the number of links for a plurality of links that are set between the same transmission / reception, so that the traffic is sufficiently improved without disconnecting the entire link. Therefore, it is possible to avoid further congestion and call loss at the time of congestion without significantly affecting the ongoing communication.

According to the third aspect of the present invention, the link number reduction executing means reduces the number of links of mobile terminals having low priority, so that the communication with high priority is prevented from being affected as much as possible. it can.

Further, according to the invention described in claim 6, the traffic detecting means detects the traffic in a plurality of stages and the link number reduction requesting means requests the link number reduction corresponding thereto, so that the traffic is not so high. Fine control over traffic is possible over time.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a processing sequence for congestion occurrence in an embodiment of the present invention.

FIG. 2 is a flowchart showing the flow of processing on the D-RNC side in this embodiment.

FIG. 3 is a flowchart showing the control contents on the S-RNC side in this embodiment.

FIG. 4 is a block diagram showing an outline of a communication system for mobile terminals.

FIG. 5 is an explanatory diagram showing a processing sequence when soft handover is performed when congestion occurs in the conventionally proposed congestion control system.

FIG. 6 is a block diagram showing a configuration of a frame relay terminal in another conventional congestion control system proposed.

[Explanation of symbols]

11 Mobile Switching Center (MMS) 12 ₁ S-RNC 122 ₂ D-RNC 13 Node 14 User Terminal 15 Radio Link

Claims (6)

[Claims] 1. A plurality of mobile terminals that perform wireless communication, a mobile communication switching center that establishes links for communication between these mobile terminals, and a mobile communication switching center that is placed under the control of the mobile communication switching center. Traffic status based on the communication means for forming a maximum of a plurality of links between the same transmission / reception with each mobile terminal to which wireless communication is allocated and performing wireless communication, and the ratio of the number of links to the allowable total number. And a plurality of wireless network control devices each having a traffic detection means for detecting, and the wireless network control device, when the traffic detection means detects traffic of a predetermined value or more,
Link number reduction requesting means for requesting from the other wireless network control device to a mobile terminal having a path set via the mobile switching center, a request to reduce the number of a plurality of links set between the same transmission and reception. A congestion control system, further comprising link number reduction executing means for executing a reduction in the number of links when a request for reducing the number of links of another wireless network control device is made. 2. A traffic detecting means for detecting a traffic state of each wireless network control device, and, when the traffic detecting means detects traffic of a predetermined value or more, other than the wireless network control device which has made the detection. Specific mobile terminal discriminating means for discriminating a mobile terminal that has moved from the wireless network control device by soft handover and has a plurality of links for wireless communication between the same transmission and reception; A link number reduction requesting means for requesting a reduction in the number of links to the mobile terminal, and a link number reducing execution means for reducing the number of links when a reduction in the number of links is requested from any radio network control device; When the link reduction execution means reduces the number of links, the wireless network Congestion, characterized in that it comprises link number reduction notifying means for notifying a device existing on a path from the work control device to the link number reduction requesting means that has requested reduction of the link number, to the device existing on the path Control system. 3. The congestion control system according to claim 1 or 2, wherein the link number reduction executing means reduces the number of links of mobile terminals having low priorities. 4. The congestion control system according to claim 3, wherein the link number reduction executing means disconnects all the links to one mobile terminal when the request is not satisfied due to the link number reduction. 5. The link number reduction notifying means notifies the mobile communication switching center that has set a path from the radio network controller before soft handover to the radio network controller after soft handover. The congestion control system according to claim 2, wherein the congestion control system is notified. 6. The congestion according to claim 1, wherein the traffic detecting means detects traffic in a plurality of stages, and the link number reduction requesting means makes a request for link number reduction in response to the detected traffic. Control system.