JP4548125B2 - Congestion control method and apparatus - Google Patents

Description

  The present invention relates to a congestion control method and apparatus, and in particular, monitors and detects an overload state of a wireless communication system called “congestion control” in wireless network communication, and maintains the system in a stable state so as not to cause congestion in a wireless area. The present invention relates to a congestion control method and apparatus.

  In today's information age, users can communicate with other terminals using a communication terminal, that is, send and receive data. Each user can communicate at any time within the service area of the network. However, in any network, there is a limit to the number of terminals that can be accommodated or provided with services simultaneously. Therefore, when terminals exceeding the capacity of the network access simultaneously, the capacity is exceeded, so that so-called “congestion control” is required to restrict all call settings.

  Prior art relating to or related to such techniques is disclosed in several technical literatures. ARQ QOS control method in a radio communication network that guarantees a class of service quality required by a user corresponding to a traffic state, shortens a resolution time of a congestion state, and guarantees a service quality of a call having a high priority during communication And a control system is disclosed (for example, refer to Patent Document 1). In addition, a communication restriction control method is disclosed that efficiently performs communication restriction due to a sudden increase in traffic in the TDMA-TDD mobile communication system, thereby preventing an overload of a base station and preventing abnormal operation of the system (for example, (See Patent Document 2). In addition, when a call exceeding a certain processing level is received on the base station side, the restriction is triggered. Therefore, if abnormal congestion occurs in a specific base station, the conventional incoming call restriction method that falls into a congestion state before the restriction is triggered There is disclosed a base station incoming call restriction method for abnormal congestion that is improved by registering a restriction condition for a base station that is desired to restrict incoming calls with a command when there is a possibility of congestion (see, for example, Patent Document 3). .)

JP 2001-36578 A (page 4, FIG. 1) JP-A-4-373324 (page 3, FIG. 1) Japanese Laid-Open Patent Publication No. 10-336321 (page 3, FIG. 1)

  A general congestion control will be described with reference to FIG. FIG. 10 is a schematic diagram relating to a threshold for detecting a congestion state determined by the radio network controller. The horizontal axis represents time, and the vertical axis represents power (traffic state). At time t1 when traffic gradually increases from time t0 and reaches the congestion start threshold TL1, congestion control starts. Thereafter, the congestion control is released at time t2 when the traffic decreases and reaches the congestion release threshold TL2. Therefore, the time t1 to the time t2 is a period for restricting all call settings.

  However, the conventional congestion control as described above has the following problems. That is, when it approaches an overload state, it tries to avoid the congestion state as early as possible for all mobile devices regardless of the real-time communication service or non-real-time communication service. As a result, the real-time communication service is also forcibly disconnected. In addition, since the acceptance of new calls is also restricted in order to suppress new congestion until the congestion state is avoided, this leads to an increase in the call loss rate of the entire system.

  Furthermore, data communication services are increasing in recent years, and it is considered that the downlink transmission power increases or decreases in bursts due to the burstiness of data communication. If the congestion state is remarkably generated due to the burst property, the communication quality of the real-time communication service cannot be maintained.

  In order to solve the above-described problems, the congestion control method and apparatus according to the present invention employs the following characteristic configuration.

(1) In a congestion control method for maintaining communication quality by restricting a radio area of a radio base station from becoming a congestion state due to an increase in communication load by a plurality of mobile devices by a processing operation by a radio network controller,
A congestion control method for detecting approaching the congestion state before entering the congestion state, and for stepwise regulating the entry into the congestion state based on the detection result.
(2) The congestion control method according to (1), wherein the congestion state is regulated by call setting restriction and communication speed (or data rate) restriction.
(3) The congestion control method according to (2), wherein the call setting is first restricted and then the communication speed is restricted.
(4) The approach to the congestion state is performed by setting the circuit switching (CS) restriction start threshold and the CS restriction release threshold, and the packet switching (PS) restriction start threshold and the PS restriction release threshold. 2) Congestion control method.
(5) One or more radio base stations that provide services to a plurality of mobile stations in a radio area and a radio network control device that controls radio of the radio base stations are provided, and the radio base stations are congested. In the congestion control device that regulates
When a plurality of restriction start thresholds and a plurality of restriction release thresholds are set in advance by the wireless network control device, and the conditions are determined by comparing and judging the plurality of threshold values and downlink transmission power, the congestion state is generated by the wireless network control device. A congestion control device that reduces the frequency.
(6) The congestion control apparatus according to (5), wherein the comparison and determination of the plurality of threshold values and the downlink transmission power are performed by the radio base station.
(7) The radio base station periodically reports downlink transmission power to the radio network control apparatus, and the radio network control apparatus compares and determines the reported downlink transmission power and the plurality of threshold values. 5) The congestion control device.
(8) The plurality of threshold values are the line switching (CS) restriction start threshold value, the CS restriction release threshold value, the packet switching (PS) restriction start threshold value, and the PS restriction release threshold value (5), (6), or (7) Congestion control device.

  According to the present invention, the following practical effects can be obtained. That is, by reducing the communication speed of PS calls, resources allocated for PS calls can be allocated to resources for calls requiring high priority such as CS calls and emergency calls. It is possible to ensure quality and reduce the call loss rate for communication services and high priority communication services. Furthermore, since the communication speed of the PS call is suppressed and the number of PS calls accommodated is regulated before the congestion state occurs, the frequency of the congestion state can be reduced.

  First, the configuration and operation of a preferred embodiment of a congestion control method and apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is an explanatory diagram of a congestion control method and apparatus according to the present invention. FIG. 1 shows a radio network controller (RNC) 11 and nodes 21 and 22 which are radio base station apparatuses each having radio areas 41 and 42, respectively.

  Here, the radio network control device 11 performs control related to radio. The nodes 21 and 22 monitor the wireless state and report the measurement result to the wireless network control device 11. The radio area 41 and the radio area 42 are areas (or cells) covered by the node 21 and the node 22 that are radio base station apparatuses, respectively. These radio areas 41 and 42 usually overlap each other partially as shown in FIG. It is assumed that a plurality of mobile devices (or UEs) 31, 32, 33, and 34 exist in these wireless areas 41 and 42.

  The radio network controller 11 has a congestion determination function for determining whether or not the radio areas 41 and 42 are in a congested state based on received signal strength and downlink transmission power monitored by the radio base station apparatuses 21 and 22. In addition, the node 21 and the node 22 that are radio base station apparatuses have a function of comparing the threshold value determined by the radio network control apparatus 11 and the received signal strength or downlink transmission power in the radio area. Further, the node 21 and the node 22 can notify the radio network control device 11 that the condition requested by the radio network control device 11 is satisfied.

  This system employs a CDMA (Code Division Multiple Access) system as a radio access system, and supports a plurality of communication services. A real-time communication service is provided as the first communication service, and a non-real-time communication service is provided as the second communication service.

Voice communication exists as a representative service of the real-time communication service. In voice communication, information is transmitted by circuit switching (CS). Data communication exists as one of non-real time communication services. Data communication uses packet switching (PS:
Information is transmitted by Packet Switch). Therefore, in the following description, voice communication is referred to as a CS call, and data communication is referred to as a PS call.

  Next, the operation of the congestion control method and apparatus according to the present invention will be described with reference to the operation explanatory diagram of FIG. In FIG. 2, the horizontal axis represents time, and the vertical axis represents power. That is, FIG. 2 shows a CS call restriction start threshold TL1 indicating the start of CS call restriction on the downlink transmission power in the radio network control apparatus 11, a CS restriction release threshold TL2 indicating the restriction release of the CS call, and a PS call restriction start. PS call restriction start threshold value TL3 indicating PS and PS call restriction release threshold value TL4 indicating release restriction of the PS call are determined. As shown in FIG. 2, the CS call restriction start threshold value TL1 is a threshold value indicating that the wireless areas 41 and 42 are in a congested state. The value is determined so as to be low.

  Since the CS call restriction start threshold TL1 indicates that the wireless area 41 or 42 is in a congested state, the wireless network control device 11 also restricts a high-priority communication service or CS call. However, the PS call restriction start threshold TL3 does not fall into a congestion state, so only PS calls are restricted. At that time, in order to prevent a congestion state, the PS call that is carrying out the communication service is regulated to suppress traffic.

  More specifically, in the specific state shown in FIG. 2, at time t0 to t1, since the power is equal to or less than the PS regulation start threshold TL3, no (that is, PS and CS) call regulation is performed. From time t1 to t2, PS call restriction is performed, but CS call restriction is not performed. On the other hand, at time t2, in order to indicate that the wireless area 41 or 42 has entered a congestion state exceeding the CS call restriction start threshold TL1, the wireless network control device 11 can make a high priority communication service or CS call. It also regulates. Accordingly, the time t1 to t4 is a period for restricting the PS call setting. Times t2 to t3 are periods for restricting CS call setting.

  Next, FIG. 3 is a diagram for explaining the operation between the devices in the system shown in FIG. The conditions (threshold values) as shown in FIG. 2 are notified from the wireless network control device 11 to the nodes 21 and 22 (step 1). The node 21 and the node 22 that have received this condition monitor the state of the downlink transmission power of the radio areas 41 and 42. That is, the threshold values TL1 to TL4 shown in FIG. 2 are compared and determined with the downlink transmission power (step 2). When the downlink transmission power state satisfies the condition notified from the radio network control apparatus 11, the nodes 21 and 22 notify the radio network control apparatus 11 that the condition is satisfied (step 3).

  Therefore, the wireless network control device 11 performs a restriction process according to the notification from the nodes 21 and 22 (step 4). That is, when the PS call restriction start threshold value TL3 is exceeded, the restriction is started so as not to accept the PS call setting request until the restriction is released. Further, a mobile device capable of changing a communication speed to suppress traffic for a mobile device UE that implements or provides a PS call service in the wireless areas 41 and 42 in order to release the restriction state. Select a UE. If the PS call restriction release threshold value TL4 is not reached, the call setting and communication speed restriction for the PS call is released, and the radio network controller 11 determines that it can be avoided from the restricted state.

  On the other hand, when the CS call restriction start threshold value TL1 is exceeded, the radio network controller 11 determines that the radio areas 41 and 42 have become congested and restricts the call setting request for the CS call from being accepted. To start. Further, in order to cancel the congestion state, the mobile device UE that performs the service by the PS call in the radio areas 41 and 42 is the target, and the mobile device UE is used to change the communication speed or change to the common channel. Select. If the congestion state is not resolved even if the PS call is restricted, the mobile station UE that performs the service by the CS call in the radio areas 41 and 42 is forcibly released.

  If the CS call restriction release threshold value TL2 is not reached, the call setting for the CS call is released, and the radio network controller 11 determines that it can be avoided from the congestion state. On the other hand, for PS calls, PS call restriction is continued until it falls below the PS call restriction release threshold TL4.

  Next, the overall operation of the congestion control method and apparatus according to the present invention will be described in detail with reference to the flowcharts of FIGS. First, FIG. 4 shows comparison processing between downlink transmission power and threshold values TL1 to TL4 in the node 21 and the node 22 which are wireless base stations. Nodes 21 and 22 which are wireless base stations monitor the amount of power being transmitted. Then, it is determined whether or not the transmission power exceeds the PS regulation start threshold value TL3 (step A1). If it exceeds TL3 (step A1: YES), the nodes 21 and 22 determine that PS regulation is started, and notify the radio network controller 11 that PS regulation needs to be started (step A2).

  On the other hand, if the power is below the PS regulation release threshold TL3 (step A1: NO), it is determined whether or not the power is below the PS regulation release threshold TL4 (step A3). When the power is lower than TL4 (step A3: YES), the radio network controller 11 is notified that the PS regulation needs to be released (step A4). Next, when the transmission power is not lower than TL4 (step A3: NO), it is determined whether or not the power exceeds the CS regulation start threshold TL1 (step A5). If TL1 is exceeded (step A5: YES), the nodes 21 and 22 determine that CS restriction is being implemented, and notify the wireless communication network control device 11 that CS restriction needs to be started (step A6). ). If it does not exceed TL1 (step A5: NO), it is determined whether or not the transmission power is below the CS restriction release threshold TL2 (step A7). If the value is below the CS restriction release threshold TL2 (step A7: YES), it is determined that the CS restriction is released, and the wireless network control device 11 is notified that the CS restriction needs to be released (step A8). Exit.

  Next, FIG. 5 is a flowchart showing the operation of the radio network controller 11 when the start of PS regulation is notified from the radio base stations (nodes 21 and 22). First, the presence / absence of a CS call setup request is determined (step B1). When this request is generated (step B1: YES), the call setting is not regulated and the call setting is accepted (step B2) because the congestion state is not established. On the other hand, if there is no CS call setup request (step B1: NO), it is determined whether there is a PS call setup request (step B3). If there is a PS call setup request (step B3: YES), PS call setup is restricted to maintain the quality of the CS call (step B4). On the other hand, when there is no PS call setting request (step B3: NO), in order to cancel the restriction state, a PS call in service is extracted, that is, it is determined whether there is a PS call in service. (Step B5).

  If there is no PS call (step B5: NO), the process is terminated, and if it exists (step B5: YES), it is determined whether a high data rate is being used (step B6). When the high data rate is being used (step B6: YES), the data rate is restricted to a low data rate (step B7). On the other hand, when the high data rate is not being used (step B6: NO), the process is terminated as it is. The PS call extraction process is repeated at regular intervals until the restricted state is released.

  Next, FIG. 6 is a flowchart showing the processing operation when the transmission power exceeds the CS regulation start threshold value TL1. First, the presence / absence of a CS call setup request is determined (step C1). If there is a CS call setup request (step C1: YES), the call setup is restricted because of the congestion state (step C2). On the other hand, if there is no CS call setup request (step C1: NO), it is determined whether there is a PS call setup request (step C3). If there is a PS call setting request (step C3: YES), the PS call setting is also restricted because of the congestion state (step C4). When there is no PS call setting request (step C3: NO), in order to release the congestion state, a PS call in service is extracted, that is, it is determined whether there is a PS call in service (step S3). C5). If there is a PS call in service (step C5: YES), it is determined whether a high data rate is being used (step C6). If a high communication speed is used (step C6: YES), the communication speed is restricted to a low communication speed (step C7).

  On the other hand, when the high data rate is not used (step C6: NO), it is determined whether or not the low data rate is being used (step C8). For PS calls that are already communicating at a low communication speed (step C8: YES), a change to the common channel is performed (step C9). If the congestion state is not canceled even after all PS calls have been extracted, CS calls are extracted. When the low data rate is not being used (step C8: NO), it is determined whether or not there is a CS in service (step C10). For the CS call whose presence has been extracted (step C10: YES), forcible release is performed to release the congestion state (step C11). Note that the extraction process of the mobile device UE is repeated at regular intervals until the congestion state is released.

  Next, FIG. 7 shows the radio network controller 11 when the radio base station (nodes 21 and 22) notifies the cancellation of CS restriction (that is, when the transmission power falls below the CS release restriction threshold TL2). It is a flowchart which shows operation | movement. First, the presence / absence of a CS call setup request is determined (step D1). When a CS call setting request is generated (step D1: YES), the congestion state is released, so that the call setting is accepted, that is, the call setting is not regulated (step D2). If there is no CS call setting request (step D1: NO), it is determined whether there is a PS call setting request (step D3). If there is a PS call setting request (step D3: YES), call setting is restricted to maintain the quality of the CS call (step D4).

  On the other hand, when there is no PS call setting request (step D3: NO), in-service PS calls are extracted to release the restricted state (step D5). If there is a PS call in service (step D5: YES), it is determined whether or not a high communication speed is used (step D6). When a high data rate is used (step D6: YES), the communication speed is restricted to a low communication speed (step D7). When the high data rate is not used (step D6: NO), it is determined whether or not the low data rate is used (step D8). That is, for PS calls that are already communicating at a low communication speed (step D8: YES), the change to the common channel is performed (step D9), and the CS call extraction process is stopped. The PS call extraction process is repeated at regular intervals until the restricted state is released.

  Next, FIG. 8 shows the processing operation of the radio network controller 11 when the transmission power is lower than the PS restriction release threshold TL4, that is, when the PS restriction release notice is given from the radio base station (nodes 21 and 22). It is a flowchart to show. Since the restriction state is released, restriction processing is not performed even when a CS call setting request is generated. The PS call extraction process performed to release the restricted state is stopped.

  That is, it is determined whether or not there is a CS call setting request (step E1). If there is a CS call setup request (step E1: YES), call setup is not restricted (step E2). On the other hand, if there is no CS call setup request (step E1: NO), it is determined whether there is a PS call setup request (step E3). Even when there is a PS call setting request (step E3: YES), call setting is not restricted (step E4).

  Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 9 is an explanatory diagram corresponding to FIG. 3 of the first embodiment described above. The basic configuration of the second embodiment is the same as that of the first embodiment described above, but further improvements are made to the threshold comparison process. That is, in FIG. 9, the radio base stations (nodes 21 and 22) do not compare the downlink transmission power with the threshold value, and only periodically transmit the measurement results to the radio network controller 11 (step 11). Since the wireless network control device 11 performs comparison / determination with the threshold (step 12), the processing operations shown in FIGS. 5 to 8 are the same as those in the first embodiment, but the processing operation shown in FIG. This is done with the device 11. Since the radio base stations (nodes 21 and 22) do not perform comparison with the threshold value, the processing (load) of the radio base station can be reduced as compared with the first embodiment.

  The configuration and operation of the preferred embodiment of the congestion control method and apparatus according to the present invention have been described in detail above. However, it should be noted that such examples are merely illustrative of the invention and do not limit the invention in any way. Those skilled in the art will readily understand that various modifications and changes can be made according to a specific application without departing from the gist of the present invention.

It is a system configuration | structure figure of the congestion control apparatus by this invention. It is explanatory drawing of the threshold value set with the radio | wireless network control apparatus in FIG. It is explanatory drawing of 1st Example of the congestion control method by this invention. It is a determination flowchart of congestion control by a wireless base station. It is a processing flowchart in the case of exceeding the PS regulation start threshold. It is a processing flowchart in the case of exceeding the CS regulation start threshold. It is a processing flowchart in case it is less than CS regulation cancellation | release threshold value. It is a processing flowchart in case it is less than PS regulation cancellation | release threshold value. It is operation | movement explanatory drawing of 2nd Example of this invention. It is explanatory drawing of the conventional congestion control method.

Explanation of symbols

11 Wireless network control devices 21 and 22 Wireless base station (node)
31-34 Mobile device 41, 42 Wireless area

Claims (2)

For one or more radio base stations that provide communication services including a first communication service having a high priority and a second communication service having a low priority to a plurality of mobile stations in the radio area, In a congestion control method for maintaining communication quality by a wireless network control device that performs processing operations for restricting a communication load from increasing and becoming a congestion state,
First restriction threshold for starting restriction of the first communication service, first release threshold for releasing restriction of the first communication service, and restriction of the second communication service are started. A second start threshold value for canceling the restriction of the second communication service and a second release threshold value for canceling the restriction of the second communication service are set in advance so as to be a small value in the order,
Detecting increase / decrease in downlink transmission power in the radio base station based on communication with the plurality of mobile devices,
When it is detected that the transmission power has increased from a value less than the second start threshold value to a value greater than or equal to the second start threshold value, restricting acceptance of a call setting request for the second communication service; When the call setting request does not exist and the call setting data rate in the second communication service is equal to or higher than a predetermined value, the data rate is regulated to be lower than the predetermined value;
When it is detected that the transmission power has increased from a value less than the first start threshold to a value greater than or equal to the first start threshold, regulation of acceptance of a call setting request for the first communication service is restricted, When the call setting request does not exist and the call setting data rate in the second communication service is equal to or higher than a predetermined value, the data rate is regulated to be lower than the predetermined value, and the second If the call setup data rate during the communication service is less than a predetermined value, the call setup is changed to the common channel, the call setup request does not exist, and the call setup during the second communication service Disconnects the call setup in the first communication service,
When it is detected that the transmission power has decreased from a value greater than or equal to the first release threshold to a value less than the first release threshold, a call setup request for the first communication service is received, and the call setup is performed. When the request does not exist and the call setup data rate in the second communication service is equal to or higher than a predetermined value, the data rate is regulated to be lower than the predetermined value, and the second communication service If the call setup data rate is less than the specified value, change the call setup to a common channel,
Call setup of the first communication service and the second communication service when it is detected that the transmission power has decreased from a value greater than or equal to the second release threshold to a value less than the second release threshold A congestion control method characterized by receiving a request .   Multiple mobile units,
  One or more radio base stations that provide communication services including a first communication service having a high priority and a second communication service having a low priority to the plurality of mobile devices in a radio area;
  A radio network controller for controlling the radio base station to be congested;
  A congestion control system comprising:
  The radio network controller is
  First restriction threshold for starting restriction of the first communication service, first release threshold for releasing restriction of the first communication service, and restriction of the second communication service are started. A second start threshold for canceling the restriction of the second communication service and a second release threshold for canceling the restriction of the second communication service are set in advance so as to be a small value in the order, and the wireless base station Notify
  The radio base station is
  Detecting increase / decrease in downlink transmission power in the radio base station based on communication with the plurality of mobile devices, and notifying the detection result to the radio network controller,
  The radio network controller is
  When it is detected that the transmission power has increased from a value less than the second start threshold value to a value greater than or equal to the second start threshold value, restricting acceptance of a call setting request for the second communication service; When the call setting request does not exist and the call setting data rate in the second communication service is equal to or higher than a predetermined value, the data rate is regulated to be lower than the predetermined value;
  When it is detected that the transmission power has increased from a value less than the first start threshold to a value greater than or equal to the first start threshold, regulation of acceptance of a call setting request for the first communication service is restricted, When the call setting request does not exist and the call setting data rate in the second communication service is equal to or higher than a predetermined value, the data rate is regulated to be lower than the predetermined value, and the second If the call setup data rate during the communication service is less than a predetermined value, the call setup is changed to the common channel, the call setup request does not exist, and the call setup during the second communication service Disconnects the call setup in the first communication service,
  When it is detected that the transmission power has decreased from a value greater than or equal to the first release threshold to a value less than the first release threshold, a call setup request for the first communication service is received, and the call setup is performed. When the request does not exist and the call setup data rate in the second communication service is equal to or higher than a predetermined value, the data rate is regulated to be lower than the predetermined value, and the second communication service If the call setup data rate is less than the specified value, change the call setup to a common channel,
  Call setup of the first communication service and the second communication service when it is detected that the transmission power has decreased from a value greater than or equal to the second release threshold to a value less than the second release threshold A congestion control system characterized by receiving a request.

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