KR20100063584A - Method for providing abr service in mobile communication system and base station controller using the same - Google Patents

Abstract

PURPOSE: A method for providing abr service in a mobile communication system and a base station controller using the same are provided to comprise RM cell transceived between source and destination by F-RM cell and R-RM cell, thereby preventing traffic overhead in message transfer of a outband type. CONSTITUTION: A random arbitrary component of ATM(Asynchronous Transfer Mode) mobile communication system functions as ABR(Available Bit Rate) source or ABR destination. If the F-RM cell is received, the ABR destination transmits R-RM(Reverse-Resource Management) to the ABR source. The ABR source and the ABR destination are located in BSC(Base Station Controller) which controls one or more BSs(140~143). The R-RM cell includes congestion prediction information of network related to the BSC.

Description

Method of providing AVR service of mobile communication system and base station controller using same {METHOD FOR PROVIDING ABR SERVICE IN MOBILE COMMUNICATION SYSTEM AND BASE STATION CONTROLLER USING THE SAME}

The present invention relates to a mobile communication system, and more particularly, to traffic management in a hand-off period of a mobile communication system.

Today's mobile communication systems are dominated by ATM-based mobile communication systems. Asynchronous Transfer Mode (ATM) refers to a technology for realizing a multimedia communication network that transmits all voice, video, and data to one network.

The ATM Forum and ITU-T define the ABR (Available Bit Rate) function as one of the traffic services provided by ATM exchanges. By applying the ABR service to traffic having a large and variable burst characteristics, it is possible to transfer the maximum bandwidth existing in the network to the maximum. In the ABR service, when a congestion occurs in an ATM network and a loss of an ATM cell requires a plurality of packets to be retransmitted, the ABR service applies a congestion control scheme through feedback to a cell caused by congestion of the network. It is specified to prevent loss and provide minimal bandwidth.

In a conventional ATM mobile communication system, a base station controller and a base station are connected by a narrowband E1 line, and a main switching station that manages the base station controller and the base station controller is connected by a synchronous transmission module 1 (hereinafter referred to as STM-1) line. An 53-byte ATM cell is transmitted and received between the base station controller and the main switching center. At this time, for efficient use of the E1 line and the STM-1 line, the traffic message uses an AAL2 type ATM cell and the control message is transmitted using an AAL5 type ATM cell.

The narrow band E1 section of the mobile communication system is exposed to the possibility of being always congested by burst traffic. In particular, since hand-off calls go through more network paths than non-handoff calls, network congestion is relatively more likely to occur in the narrow band E1 interval. Accordingly, there is a need for efficient traffic management for handoff calls in ATM mobile communication systems.

Traffic of the handed off call is carried over a path including a network path of AAL2 type. However, an RM cell (Resource Management Cell), which is a traffic control message for an ABR service, is defined as an AAL5 type. Since the prior art for transmitting an AAL5 type RM cell in an AAL2 type network path is not known, when a conventional mobile communication system transmits and receives a traffic control message for an ABR service for a handoffed call, the RM cell is generally RM. Information to be transmitted / received to the cell is transmitted and received in an out-band manner through an application message separate from AAL2 traffic.

As such, since the traffic control message is transmitted in an outband manner separately from the traffic, overhead may occur in the network path. As the number of subscribers increases, the amount of traffic control messages to be transmitted increases as traffic increases, which may adversely affect high-speed broadband data services.

Another problem of the conventional mobile communication system is that in using the ABR service function, there may be a delay in transmitting a traffic control message. For example, when network congestion is predicted in the narrow band E1 interval, it is essential to effectively reduce the traffic rate of each subscriber by transmitting a traffic control message quickly. However, in the conventional mobile communication system, since a subject for transmitting and receiving a traffic control message corresponds to each base station, a propagation delay on a transmission path between the base station and the base station controller and a processing delay at the base station and the base station controller This can happen. If the delay of the traffic control message (eg, network congestion prediction information) is delayed due to such a delay, the traffic control message may be transmitted late after the network congestion has occurred and thus may not effectively control the traffic rate.

In order to solve the above problems, the present invention provides a method for preventing the traffic overhead of transmitting and receiving traffic control messages in an outband manner in providing the ABR service of the ATM mobile communication system. The present invention also provides a mobile communication system capable of minimizing a delay in transmitting a traffic control message.

In one embodiment of the present invention, a method for providing an ABR (Available Bit Rate) service via an AAL2 network section in an ATM mobile communication system capable of data communication is provided, wherein the ABR source is ABR. Transmitting an F-RM cell to an ABR destination and correspondingly to receiving the F-RM cell, the ABR destination transmitting an R-RM cell to the ABR source, wherein the ABR source And the ABR destination is located in a base station controller that controls one or more base stations, wherein the R-RM cell includes congestion prediction information of a network associated with the base station controller where the destination is located. In one embodiment, the F-RM cell and the R-RM cell are standard OAM cells of an ATM Forum.

In one embodiment of the present invention, an apparatus for providing an ABR service via an AAL2 network section in an ATM mobile communication system capable of data communication is provided, and the apparatus includes an RM cell transmitter and an RM cell for transmitting an RM cell. Included in the base station controller for controlling one or more base stations for receiving and operating as an ABR source and an ABR destination, the RM cell transmitter converts AAL5 type traffic to AAL2 type and AAL5 type It is operable to transmit the VPC information of the RM cell to the AAL5 type traffic in accordance with the AAL5 type traffic, the RM cell receiver divides the received cell into AAL2 type traffic and AAL5 type RM cell, It is operable to convert AAL2 type traffic to AAL5 type.

By configuring the RM cell that is exchanged between the source and the destination with the F-RM cell and the R-RM cell recommended in the standard ABR, it is possible to prevent the traffic overhead that occurs when the message is delivered in an outband manner. In addition, by positioning the destination at the base station controller, the delay in message transmission for the ABR function is minimized.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, components generally known in the art are not shown in order not to unnecessarily obscure the description of the present invention.

1 illustrates a mobile communication system according to an embodiment of the present invention. The system shown in FIG. 1 is a sample of the CDMA2000 1x EVDO system, but the WCDMA system is not much different. In one embodiment, mobile communication system 100 may include a Central Area Network (CAN) 120, base station controllers 130 and 131, base stations 140-143, and subscriber station 150. . The mobile communication system 100 may further include a Packet Data Serving Node (PDSN) 160 for data communication. The PDSN 160 may be connected to the CAN 120 by Ethernet. Each component of the mobile communication system 100 forms a layer, and each component is connected to communicate with an upper component and a plurality of lower components. The subscriber station 150 is connected to communicate with the base station 140 covering the area where the subscriber station 150 is located.

In the embodiment shown in FIG. 1, CAN 120 is connected to two base station controllers 130 and 131, and each base station controller 130 and 131 is connected to two base stations 140, 141 or 142, 143. Although the configuration is shown, it is not limited thereto. For example, CAN 120 may be connected with any one or more base station controllers, and each base station controller may also be connected with one or more any number of base stations. In one embodiment, the mobile communication system 100 may further include additional layers other than the layers shown in FIG. For example, there may be a higher level control device connected to multiple CANs.

The base station controllers 130 and 131 and the base stations 140 to 143 may be connected to a narrow band E1 line. The base station controllers 130 and 131 and the CAN 120 may be connected to the STM-1 line. A 53-byte ATM cell may be transmitted and received between the base stations 140-143, the base station controller 130, and the CAN 120. In this case, in order to efficiently use the E1 line and the STM-1 line, an AAL2 type ATM cell is used for transmitting and receiving a traffic message, and an AAL5 type ATM cell is used for transmitting and receiving a control message.

According to the ABR service specification, any component in an ATM mobile communication system will function as an ABR source (hereinafter referred to as "source") or an ABR destination (hereinafter referred to as "destination"). The source and the destination transmit and receive the RM cell (Resource Management Cell) with the traffic at regular intervals. The RM cell is used to convey ATM network state (eg, available bandwidth, congestion, etc.) and is a standard 53 byte ATM cell. The RM cell is composed of an F-RM cell and a R-RM cell. An F-RM cell is an RM cell that a source transmits to a destination, and an R-RM cell is an RM cell that a destination feeds back to a source.

The source transmits the F-RM cell to the destination, receives the response from the destination, and performs traffic control accordingly. The destination may, in response to receiving the F-RM cell, transmit to the source an R-RM cell containing state information (eg, congestion, network congestion prediction, etc.) of current traffic. The source enables traffic control based on information included in the received R-RM cell. In one embodiment, the RM cell that the source and destination transmit and receive may be a standard OAM cell specified in the ATM forum.

In one embodiment of the present invention, the base station controllers 130 and 131 of the mobile communication system 100 perform the functions of the source and the destination. This is different from the ABR function of the conventional mobile communication system in which the base station controllers 130 and 131 serve as sources, and the base stations 140 and 143 serve as destinations. To perform these functions as a source and a destination, the base station controller includes an RM transmitter and an RM receiver.

In one embodiment, if the RM transmitter of the source transmits the F-RM cell to the destination, the RM receiver of the destination receives it, and in response, if the RM transmitter of the destination transmits the F-RM cell to the source, The RM receiver receives it. However, since a network path through which data is delivered after the handoff occurs may include an AAL2 type network path, an AAL2 type network path may exist between a source and a destination. However, since the standard RM cell defined for the ABR service is an AAL5 type ATM cell, the RM transmitter and the RM receiver have an appropriate conversion mechanism in order to transmit and receive RM messages in-band with AAL2 type traffic. It must be included.

2 is a schematic structural diagram of an RM transmitter according to an embodiment. This structure applies equally to the RM transmitter of the source and the RM transmitter of the destination. Referring to the operation of the RM transmitter 200 based on the structural diagram of FIG.

In one embodiment, the RM transmitter 200 includes a cell receiver 210, a cell routing unit 220, a traffic converter 230, an RM cell processor 240, a cell transmitter 250, a processor 260, VPC information providing unit 270 may be configured.

The RM transmitter 200 may transmit traffic to be relayed by the base station controller and an RM cell prepared by the base station controller as a source or a destination. The cell receiver 210 receives an ATM cell to be transmitted (that is, traffic to be relayed or prepared RM cell) from a predetermined function unit (not shown) in the base station controller and transmits it to the cell routing unit 220. The cell routing unit 220 determines whether the ATM cell transmitted from the cell receiving unit 210 is a traffic or an RM cell. In one embodiment, the RM cell is a standard OAM cell specified in the ATM Forum, with the PTI field in its header set to 6 ("110"). The cell routing unit 220 reads the PTI fields of the headers of all the received ATM cells. A cell having a read value of 6 ("110") is determined as an RM cell and transmitted to the RM cell processing unit 240, and other cells are determined to be traffic and transmitted to the traffic converter 230.

On the other hand, the processor 260 of the RM transmitter receives the VPC (Virtual Path Connection) information of the subscriber through a predetermined path (not shown) and delivers it to the VPC information provider 270. The VPC information provider 270 stores the transferred VPC information.

The traffic converter 230 converts the AAL5 type traffic transmitted from the cell routing unit 220 into the AAL2 type traffic. It is known to convert AAL5 type ATM cells to AAL2 type and vice versa. The converted traffic is transmitted to the cell transmitter 250.

3 shows a schematic structure of the RM cell processing unit 240. The RM cell processor 240 may include a VPC converter 302, a CID inserter 304, and a CRC processor 306. The VPC converter 302 may read the VPC information stored in the VPC information provider 270 and insert the VPC information into the RM cell transferred from the cell routing unit 220. In one embodiment, the VPC converter 302 converts AAL5 VP / VC to AAL2 VP / VC when the AAL5 VP / VC of the RM cell delivered from the cell routing unit 220 is equal to the stored VP / VC.

The CID inserting unit 304 may insert the CID information into the RM cell in which the VPC information is converted. In one embodiment, the CID inserting unit 304 inserts the CID information into the 22nd octet inside the RM cell. 6 is an RM cell format specified in the ATM Forum. As shown in FIG. 6, since the 22nd to 52nd octets of the RM cell are reserved octets, the 22nd octet may be used to store the CID.

The CRC processing unit 306 resets the cyclic redundancy check (CRC) value of the RM cell into which the CID information is inserted. The 22nd octet of the RM cell is set to 0x6A by default, but since CID information is arbitrarily inserted by the CID inserting unit, the CRC value of the corresponding RM cell should be recalculated and set. This is because if the CRC is not calculated and set again, it may be regarded as a CRC error by the passing network node and discarded before reaching the RM receiver via an AAL2 type network node (eg, CAN). Accordingly, the RM cell processing unit 240 calculates the CRC of the payload portion (0 to 5 bits of the 6th to 52th octets) of the cell with respect to the RM cell into which the CID information is inserted. Insert the calculated CRC into 6 ~ 7 bits and 53rd octet. As shown in FIG. 6, the CRC calculation method of the RM cell is CRC-10.

Through this process, the RM cell to be transmitted has the same VPC as traffic converted to AAL2, and may include CID information and a modified CRC value. Referring back to FIG. 2, the RM cell processed by the RM processor 240 is transferred to the cell transmitter 250. The cell transmitter 250 transmits the traffic transmitted from the traffic converter 230 and the RM cell in an AAL2 type network section.

4 is a schematic structural diagram of an RM receiver according to an embodiment. This structure applies equally to the RM transmitter of the source and the RM transmitter of the destination. Referring to the operation of the RM receiver 400 based on the structural diagram of Figure 4 as follows.

The RM receiver 400 performs a function corresponding to the RM transmitter. In an embodiment, the RM receiver 400 may include a cell receiver 410, a cell routing unit 420, a traffic converter 430, an RM cell playback unit 440, a cell transmitter 450, a processor 460, It consists of a VPC information providing unit 470.

The cell receiver 410 may receive an ATM cell including the AAL2 type traffic and the AAL5 type RM cell and transmit the received ATM cell to the cell routing unit 420. The cell routing unit 420 may divide the received ATM cell into traffic and RM cell. In one embodiment, the operation of the cell routing unit 420 is the same as the cell routing unit 420 shown in FIG. That is, the cell routing unit 420 may determine whether the received cell is a traffic or an RM cell by reading the PTI field of the header of the received cell. A cell having a PTI field value of 6 (“110”) may be determined as an RM cell and transmitted to the RM reproducing unit 440, and other cells may be determined to be traffic and transmitted to the traffic converter 430.

The processor 460 of the RM receiver 400 performs the same function as the processor 260 of the RM transmitter 200 described above. That is, the processor 460 receives the VPC information of the subscriber through a predetermined path (not shown). The received VPC information is stored in the VPC information provider 470.

The traffic converter 430 receives the ATM cell determined to be traffic by the cell routing unit 420, and converts the AAL2 type traffic into the AAL5 type. The converted traffic is transmitted to the cell transmitter 450.

5 is a schematic structural diagram of the RM reproducing unit 440. The RM playback unit 440 may include a CID extractor 502, a VPC converter 504, and a CRC processor 506. The CID extractor 502 may extract and store the CID information inserted into the RM cell delivered from the cell routing unit 420.

The VPC converter 504 converts AAL2 VP / VC into AAL5 VP / VC using the VPC information stored in the VPC information provider 470 so that the RM cell includes the same VPC information as the traffic converted by the traffic converter 430. You can convert to VC.

The CRC processing unit 506 may insert an original value of 0x6A into the 22nd octet of the RM cell into which the CID is inserted, recalculate the CRC, and restore the original RM cell to transfer the cell to the cell transmitter 450. As a result, the traffic transmitted to the cell transmitter 450 and the RM cell have the same VPC information.

Referring back to FIG. 4, the cell transmitter 450 forwards the traffic and the RM cell to a predetermined function unit (not shown) of the base station controller to be processed as necessary.

As described above, the structures of the RM transmitter and the RM receiver have been described with reference to FIGS. 4 and 5, but the present invention is not limited thereto, and other forms of implementation of the above-described operations of the RM transmitter and the RM receiver may be implemented. Do.

As described above, by using the RM transmitter and the RM receiver according to an embodiment of the present invention, the AAL2 network section included in the traffic transmission path during handoff can transmit and receive not only AAL5 traffic but also RM cells. Therefore, a traffic control message can be transmitted and received in-band using only a standard RM cell, without transmitting and receiving a traffic control message between a source and a destination. As a result, the likelihood of generating traffic overhead is significantly reduced as compared with the case of using the outband method.

The ABR service providing method in the mobile communication system 100 will be described using a source and a destination including the above configuration. Referring back to FIG. 1, the traffic paths before and after handoff are described.

First, it is assumed that before the handoff occurs, that is, the subscriber station 150 receives the service in the area where the base station 140 covers. The path through which the subscriber station 150 receives data service is L100-L200-L300. Data is transmitted over Ethernet in L100 and AAL5 type ATM cells in L200 and L300. In this case, the base station controller 130 is responsible for both the source and destination of the ABR service. Note that the destination is located in the base station controller 130, unlike a typical mobile communication system in which the base station serves as the destination.

Sources and destinations in the base station controller 130 may transmit and receive RM cells with each other. In one embodiment, the source periodically transmits the F-RM cell to the destination. In response to receiving the F-RM cell, the destination may insert traffic control information into the R-RM cell to feed back to the source. If congestion is expected in the network region associated with the base station controller 130 to which the destination belongs, the congestion prediction information may be inserted into the R-RM cell to feed back to the source. The source may perform traffic control by reading the traffic control information carried on the R-RM cell. For example, if the received RM cell includes network congestion prediction information, the source may reduce the traffic rate for the corresponding subscriber transmitted to the destination to prevent network congestion at the destination.

Next, it is assumed that the subscriber station 150 moves to an area covered by the base station 142 and a handoff occurs. In general, even if a handoff occurs, the traffic route is changed while the corresponding call occupies the same selector. Therefore, the path through which data is transmitted is L100-L200 (CAN 120-> base station controller 130)-L200. (Base station controller 130-> CAN 120)-L201-L302. Data is transmitted as Ethernet in L100 and AAL5 type in L200 (CAN 120-> base station controller 130). In addition, L200 (base station controller 130-> CAN 120) is transmitted as AAL2 type in L201 and AAL5 type in L302.

In this case, the source of the ABR service is still in charge of the base station controller 130, which was initially served by the subscriber station 150, and the destination is set to the new base station controller 131. Note that the base station controller 131 is not responsible for the function of the destination, but the base station 142.

Similar to the case before the handoff, the source 130 and the destination 131 may transmit and receive RM cells with each other. In one embodiment, the source 130 periodically transmits the F-RM cell to the destination 131. In response to receiving the F-RM cell, the destination 131 may insert traffic control information into the R-RM cell and feed it back to the source 130. If network congestion is expected in the region of the base station controller corresponding to the destination 130, the network congestion prediction information may be inserted into the R-RM cell and fed back to the source 130. The source 130 may perform traffic control by reading the traffic control information transmitted on the R-RM cell. For example, if the received RM cell includes network congestion prediction information, the source 130 may reduce the traffic rate for the corresponding subscriber transmitted to the destination 131 to prevent network congestion of the destination.

As described above, since the destination of the ABR service is located in the base station controller rather than the base station, transmission and reception of the RM cell is performed only in the wideband period and not in the E1 narrowband period. Therefore, while using the ABR service, the impact on the throughput of the high-speed data service is very small.

In addition, since the destination of the ABR service function is located in the base station controller, the prediction congestion information in the narrow band E1 is fed back to the source without passing through the path between the base station and the base station controller, so that the propagation delay between the base station and the base station controller and Processing delay and the like can be reduced. Therefore, compared with the conventional system, the source can receive the network congestion prediction information in the narrow band E1 section more quickly, thereby effectively adjusting the traffic rate.

The above embodiments have been described with reference to the embodiments illustrated in the drawings to aid in understanding of the invention, but these are merely exemplary, and various modifications and equivalent forms of the embodiments may be obtained by those skilled in the art. I understand that it is possible. Therefore, the technical protection scope of the present invention will be defined by the appended claims.

1 is a structural diagram of a mobile communication system according to an embodiment;

2 is a schematic diagram of an RM transmitter according to one embodiment;

3 is a diagram of an RM processing unit of the RM transmitter, according to an embodiment;

4 is a schematic diagram of an RM receiver according to one embodiment;

5 is a diagram of an RM reproducing unit of the RM receiving unit according to an embodiment;

6 is an RM cell format table specified in the ATM Forum.

Claims (12)

A method of providing an ABR (Available Bit Rate) service through an AAL2 network section in an ATM mobile communication system capable of data communication, Transmitting, by an ABR source, an F-RM cell to an ABR destination; And In response to receiving the F-RM cell, the ABR destination transmitting an R-RM cell to the ABR source Including, The ABR source and the ABR destination are located in a base station controller that controls one or more base stations, The R-RM cell includes congestion prediction information of a network associated with a base station controller where the ABR destination is located, How to Provide ABR Services. The method of claim 1, The F-RM cell and the R-RM cell is a standard OAM cell of the ATM Forum, ABR service providing method. The method of claim 1, Wherein the F-RM cell and the R-RM cell include CID information and are periodically transmitted with traffic of the mobile communication system. The method of claim 3, The CID information is included in the 22nd octet of the F-RM cell and the R-RM cell. The method of claim 4, wherein And resetting the CRCs of the F-RM cell and the R-RM cell including the CID information. A mobile communication system providing an ABR service using any one of claims 1 to 4. As a base station controller providing an ABR service, An RM cell transmitter for transmitting a first type of traffic and a second type of RM cell; And RM cell receiver for receiving the first type of traffic and the second type of RM cell Including, When the base station controller operates in the first type of traffic transmission and reception mode, The RM cell transmitter is operable to convert the second type of traffic into the first type and to match the VPC information of the second type of RM cell with the converted first type of traffic, The RM cell receiver divides the received cell into a first type of traffic and a second type of RM cell, converts the first type of traffic into a second type, and converts the VPC information of the RM cell of the second type into the converted type. Operable to match traffic of a second type of Base station controller. The method of claim 7, wherein Wherein the first type is AAL2 type and the second type is AAL5 type. The method of claim 7, wherein The RM transmitter is further operable to insert CID information into the RM cell to be transmitted, And the RM receiver is further operable to extract CID information from a received RM cell. 10. The method of claim 9, And the RM transmitter is operable to insert the CID information into the 22nd octet of the RM cell to be transmitted. The method of claim 7, wherein And the RM cell receiver is operable to divide the received RM cell into AAL2 type traffic and AAL5 type RM cell based on the PTI field value of the ATM header of the received RM cell. 10. The method of claim 9, The RM transmitter is further operable to insert CID information into the RM cell to be transmitted, and then reset CRC information of the RM cell to be transmitted, And the RM receiving unit is further operable to extract CID information from the received RM cell and then to reset CRC information of the received RM cell.

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