KR100221322B1 - Method for connection establishment for the real-time connections using per-session frame defined by the synchronus counter operation in atm networks - Google Patents

Abstract

The present invention relates to a terminal connected to the network from one terminal by Q.2931, which is a call and connection control standard of a user network interface (UNI) of asynchronous communication mode communication method. A method for using connection-specific frames for real-time communication by an asynchronous transmission mode communication method, wherein the call and connection control standard Q.2931 can accommodate the bandwidth and end-to-end delay limit required by a predetermined connection. A first step in which a node is selected to determine a path of the connection to establish a connection; Considering the traffic characteristics of a given connection, frame size ( Determining a second step; The frame counter is operated at a user network interface node of a caller terminal, so that the frame size ( A third step of transmitting information (frame size, initial value of a frame counter) of a frame of the connection along the set path after the frame of the connection is defined; A fourth step of initializing the value of the frame counter of the next node by the initial value of the frame counter and the transmission delay from the third step; When the value of the frame counter reaches from the calling terminal to the called terminal through every node, after the frame for the connection is defined at the called terminal, the response signal (ACK) for the frame setting of the connection is returned to the calling terminal. And a fifth step of completing frame setting of the predetermined connection.

Description

Admission control method for real-time connection using frame per connection in asynchronous transmission mode communication network

The present invention relates to a connection acceptance control method of a frame for each connection defined by counter interworking in an asynchronous transmission mode communication network, and in particular, a call of a user network interface (UNI) of an asynchronous transmission mode communication method. And Q.2931, the connection control standard, as defined by counter interworking in an asynchronous transmission mode communication network in which frames for each real time connection including delay and jitter time information at each node of the asynchronous transmission mode communication network are transmitted. It relates to a connection acceptance control method of a frame for each connection.

In general, a broadband integrated service digital network (B-ISDN) connects subscribers and service providers that are concentrated or discrete based on broadband transmission and switching technology to provide continuous real-time services with a wide bandwidth distribution and clustered data services. It is a digital communication network that comprehensively provides various services.

As such, in order to effectively process various services, ITU-T adopts an asynchronous transfer mode (ATM) as a communication method of BISDN. The asynchronous transmission mode communication method is a packet transfer method using an asynchronous time division multiplexing method, and various services can be uniformly processed by the advantages of the existing circuit switching method and the packet switching method.

In the future, asynchronous transmission mode networks will have many services that are unpredictable at present, and will have very different traffic characteristics, both qualitatively and quantitatively. In general, the service has various quality of service requirements for yield, delay, jitter, loss rate, etc., and in the network, the quality of service requirement must be guaranteed. In particular, as real-time services such as video and audio become the main services of broadband networks, the requirements for delay and jitter become very strict.

In real-time services, when information is not delivered within the time limit, it has the same effect as loss, and it is becoming very important to effectively satisfy the requirements for delay and jitter. Meanwhile, in the asynchronous transmission mode communication network, as cells from different connections interact in the switch, the cells must be properly controlled to guarantee the quality of service to the user.

1 is a diagram illustrating a call connection state through a node in a general asynchronous transmission mode communication network. In the drawings, reference numerals i-1 to i + n denote asynchronous transmission mode communication network nodes, and A to F denote subscribers.

The asynchronous transmission mode communication network is composed of a group of interconnected nodes, and data is transmitted from a source to a destination through a network of nodes. The figure illustrates the concept of data transmission, in which a node is connected to a transmission path. On the other hand, when data is input from the predetermined subscriber to the network, the data is reached through the predetermined node to reach a predetermined destination.

For example, when data is transmitted from subscriber A to subscriber D, it is first sent to node i-1 and then through node i and node i + 1 or node i + 2. To D).

In general, the queue service method determines the transmission order of cells in consideration of the relationship between cells stored in the queue. The queue service method manages three resources of the network, that is, bandwidth, delay limit, and buffer space, and these three resources are directly related to yield and delay loss rate, which are performance parameters of a service required by a user. Therefore, when the queue service method is effectively used and the three resources are used flexibly, the quality of service of the user can be guaranteed.

In addition, the queue service method is largely divided into work-conserving and nonwork-conserving. In the work preservation method, when a cell exists in a queue, the server never rests. In non-work preservation, even if a cell exists in the queue, it can not be serviced.

On the other hand, in the past, average delay and average yield were the main parameters of performance. In the past, the study on the preservation method of these parameters was the most important problem. This makes the thresholds for delay and jitter quite important.

In using the work preservation scheme, a big problem is that clustering gradually occurs as traffic passes through the network, which wastes network resources, thereby significantly reducing the jitter characteristic of the traffic. On the contrary, in the non-work preservation method, the server utilization rate is reduced because the server is not properly utilized, but the end-to-end support is sufficiently supported by a small amount of resources through the network with almost the traffic characteristics maintained. The jitter characteristic is improved. Thus, the non-work preservation scheme is more suitable for supporting continuity real-time services.

In recent years, many non-working scheduling algorithms have been proposed to effectively support real-time services. However, these algorithms become quite inefficient by using packet headers or adopting a frame structure that cannot be supported in an asynchronous transmission mode network. . The algorithm may include a hierarchical round robin (HRR) algorithm, a stop-and-go algorithm, an jitter earlyliest-due-date algorithm, a rate-controlled static priority algorithm (RCSP). Etc.

The hierarchical turn algorithm and the stop-and-go algorithm both use a frame technique. In this hierarchical turn algorithm, the number of cells that can be serviced in one frame period for each connection is limited. Cell rate jitter is guaranteed. However, the frame used in the algorithm is defined independently without interaction with neighboring nodes so that the delay occurring when the cell passes through the node varies from cell to cell, thereby preventing end-to-end delay jitter.

In the stop-and-go algorithm, a cell is transmitted in a one-to-one correspondence between frames of an input link and frames of an output link at an exchange node. Almost the same delay occurs in all cells belonging to such a connection, and end-to-end delay jitter is generated only by position translation in the frame, which is ensured by a fairly small amount.

FIG. 2A is a view showing a switching node i having an output link l connected to input links l 'and l' 'in the conventional stop-and-go queue service method, and FIG. 2B is shown in FIG. It is a figure which shows the frame structure in each shown link.

Both algorithms have inherent problems caused by the adoption of the frame technique, such as the problem of coupling between delay limits and band allocation units, and both algorithms employ a layered frame structure. The structure is a bit different.

In the hierarchical ordering algorithm, a frame of a lower level is defined by passing a part of a time slot of a higher level, and thus, a process of selecting a cell to be serviced is simplified because one time slot belongs to a frame of a specific level. . However, the number of time slots that can be allocated at each level is limited, so that even if there is extra bandwidth, a new connection may not be accepted.

In the stop-and-go algorithm, a plurality of frames of a higher level are added together to form a frame of a lower level. Therefore, the complexity of the implementation is increased by increasing the number of levels by using the static priority of the level unit in the process of selecting a cell to be serviced because one time slot is simultaneously included in the frames of several levels. In each level, the extra bandwidth is fully utilized, thereby preventing the degradation of bandwidth usage efficiency caused by the sequential algorithm.

In both algorithms, a layered frame structure is introduced to solve the coupling problem to some extent, but the coupling problem at each level still exists.

3 illustrates a delay jitter control method in a general packet communication network.

To date, non-working conservation algorithms use jitter to control jitter by scheduling using frame structures, or jitter at each node by transmitting jitter information using packet headers.

In the hierarchical ordering algorithm and the stop-and-go algorithm, the frame scheme is adopted to simplify the implementation. However, a coupling problem occurs, resulting in poor bandwidth allocation and delay limit allocation characteristics. In addition, the jitter EDD algorithm and the RCSP algorithm can separate the allocation of the bandwidth and the delay limit, but the scheduling-related information is sent for every packet, resulting in an overhead. This is a big problem for networks with small packet sizes.

Accordingly, the present invention is to solve the above problems, the real-time in the existing Q.2931 call and connection control standard of the user network interface (UNI) of asynchronous transmission mode communication method Real-time using frame-by-connection frames in an asynchronous transmission-mode network, by adding a step to define the frame of the connection, allowing real-time connection-specific frames containing delay and jitter time information at each node of the asynchronous transmission-mode network. It relates to a connection acceptance control method for the connection.

The present invention for achieving the above object is an asynchronous transmission mode communication method from one terminal to another terminal connected to the network by Q.2931 which is a call and connection control standard of a user network interface of an asynchronous transmission mode communication method. In the method of using frame-by-connection frame for real-time communication by using the call and connection control standard, Q.2931, a node is selected that can accommodate the bandwidth and end-to-end delay limit required by a predetermined connection. A first step of determining a path of; Determining a frame size of a given connection; A third frame in which the frame counter is operated at a user network interface node of a called party terminal, and information about a frame of the connection is transmitted along the set path after the frame of the connection is defined by the frame size and the initial value of the frame counter; step; A fourth step of initializing the value of the frame counter of the next node by the initial value of the frame counter and the transmission delay from the third step; When the value of the frame counter reaches from the calling terminal to the called terminal through every node, a frame for the connection is defined between the nodes, and then a response signal for the connection is returned to the calling terminal and then the frame of the predetermined connection. This is characterized by consisting of a fifth step is defined completely.

According to the present invention configured as described above, each of the asynchronous transmission mode communication networks is defined by Q.2931, which is a call and connection control standard of a user network interface (UNI) of the asynchronous transmission mode communication method. Real-time connection-specific frames containing delay and jitter time information are transmitted. In addition, in the frame for each connection of the present invention, since information related to jitter can be obtained by itself, jitter can be adjusted by each node without having to exchange information with a previous node. Therefore, the packet size is small, like the asynchronous transmission mode network, and it is very effective in controlling delay and jitter in a high speed communication network that does not support the transmission of scheduling related information.

1 is a view illustrating a call connection state through a node in a general asynchronous transmission mode communication network;

FIG. 2A shows a switching node i having an output link l connected to input links l ', l' 'in a conventional stop-and-go queue service scheme. FIG.

FIG. 2B is a view showing a frame structure in each link shown in FIG. 2A; FIG.

3 illustrates a delay jitter control method in a general packet communication network.

4 is a conceptual diagram illustrating a general ATM protocol reference model;

5 illustrates a general B-ISDN call control protocol stack;

6 is a diagram showing the structure format of an ATM cell;

7 is a diagram illustrating a call processing related message flow in a user network interface (UNI) of an asynchronous transmission mode communication network;

8 illustrates a general format of a message related to call processing at a user network interface of an asynchronous transmission mode communication network;

9 is a diagram illustrating a format for an end-to-end transmission delay information element of the information elements shown in FIG. 8; FIG.

10 is a view showing an example of jitter information transfer method by counter interworking in an asynchronous transmission mode communication network;

FIG. 11 is a view illustrating the size of frames per connection (j, j ', j'') in the connection acceptance control method of a frame for each connection defined by a counter interworking in the asynchronous transmission mode communication network according to the present invention. ),

12 is a diagram illustrating a call processing related message flow in a method for controlling a connection acceptance of a frame for each connection defined by counter interworking in an asynchronous transmission mode communication network according to the present invention;

FIG. 13 is a diagram illustrating the operation of a frame counter in the connection acceptance control method of a frame for each connection defined by counter interworking in the asynchronous transmission mode communication network according to the present invention.

* Explanation of symbols for the main parts of the drawings

1: caller, 2: network,

3: called party, i-1 to i + n: node,

A to F: Subscriber.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail

First, to simplify the understanding of the present invention briefly described asynchronous transmission mode communication method to which the present invention is applied

4 is a conceptual diagram illustrating an ATM protocol reference model. Here, the conceptual diagram includes a management plane, a control plane, and a user plane, and the management plane is composed of hierarchical management and plane management. In addition, the plane management means the overall management of the system, and the hierarchical management manages resource and usage variables and OAM information management.

In addition, the control plane manages call control and connection control information, and the user plane transmits user information. The protocol of the control plane and the user plane is composed of an upper layer, an ATM adaptation layer, an ATM layer, and a physical layer. The functions of each layer are shown in Table 1 below.

As shown in Table 1, the asynchronous transmission mode communication scheme includes a vertical structure such as a physical layer, an ATM layer, an ATM adaptation layer (AAL), and a higher protocol layer, and the AAL layer is divided and recombined. Segmentation and Reassembly sublayer (SAR) and Convergence Sublayer (CS) are included, and the physical layer is composed of a physical medium (PM) and a Transmission Convergence (TC) sublayer.

In addition, the user network interface (UNI) is implemented in Q.2931 at the third layer (layer 3) of the control plane to control the call and connection between the asynchronous transmission mode communication network and the user. "Q.2931" is a higher standard of Q.93B that extends "Q.931", which is a layer 3 protocol of ISDN, and is used in user-network interface (UNI) layer 3 for B-ISDN. This is the proposed User Network Interface Layer 3 Specification for Basic Call / Connection Control.

In addition, in the third layer (layer 3) of the control plane, the network interface (NNI) is implemented as B-ISUP, and the related ITU-T standards are Q.2761 to Q.2764.

5 is a diagram illustrating a general B-ISDN call control protocol stack. First, the UNI call control protocol in the User Network Interface (UNI) is defined by Q.2931, and the Service Specific Connection Oriented Protocol (SAAL SSCOP) of the signaling AAL layer is Q.2130 and Q.2110. To be prescribed by The AAL Service Specific Coordination Function (SSCF) is specified by I.363, the ATM layer is defined by I.361, and the physical layer is defined by I.432, respectively.

Next, looking at the specifications in the network node interface (NNI), the user part (B-ISUP: B-ISDN User Part) is Q.2761 to Q.2764, the message transmission unit 3 (B-MTP: B-ISDN Message Transfer Part 3) is defined by Q.2210, SAAL SSCOP by Q.2140 and Q.2110, respectively, AAL SSCF layer by I.363, ATM layer by I.361, and physical layer by I.432 Will be.

When these protocols are compared with the corresponding layer of Open System Interconnection (OSI), Q.2931 and Q.2761 through Q.2764 correspond to OSI layer 3, SAAL SSCOP, AAL SSCF correspond to OSI layer 2, and ATM. The layer and the physical layer correspond to OSI layer 1.

That is, the Q.2931 message of layer 3 is segmented to 48 bytes in length through SSCOP, SSCF, and CPCS of signaling adaptation layer (Signalling AAL 5), and thus, ATM layer. After 5 bytes of headers are added, a plurality of 53 bytes of ATM cells are mapped and transmitted.

6 is a diagram illustrating the structure format of a general ATM cell. In this case, the format is divided into a header of 5 bytes and a pay-load of 48 bytes. In the header structure of 5 bytes used in the user network interface (UNI), the first byte is composed of 4 bits of Generic Flow Control (GFC) and 4 bits of Virtual Path Identifier (VPI). The second byte is composed of four bits of the virtual path identifier (VPI) and four bits of the virtual channel identifier (VCI).

The third byte is composed of 8 bits of the virtual channel identifier (VCI), the fourth byte is 4 bits of the virtual channel identifier (VCI), 3 bits of the payload type (PT) and the cell abandonment rank (CLP). It consists of 1 bit of: Cell Loss Priority, and the fifth byte consists of 8 bits of header error control (HEC).

FIG. 7 is a diagram illustrating a call processing related message flow in a user network interface (UNI) of an asynchronous transmission mode communication network. Here, the figure shows a call processing process between a calling party 1 and a network 2 and a called party.

First, a virtual channel connection (VCC) is formed through a signaling adaptation layer (VCalling ALL) in order to perform call and access control, and a payload ( user data) The connection for delivery is controlled. And, the message used for call / access control is used for B-ISDN call / access control message as shown in the following Table 2, and for call / access control between N-ISDN and B-ISDN as shown in Table 3 below. There are messages to be used in the global call reference as shown in Table 4 below.

In FIG. 7, the messages of Tables 2 to 4 generated according to Q.2931 are transmitted using the 'AAL-DATA-REQUE ST' primitive of the signal AAL (SAAL).

On the other hand, if a "SETUP" message is generated to establish a call from the caller 1 and then transferred to the network through the assigned signaling virtual channel (VCI = 5) and the timer T303 is started, the "call initialization" (Call Initiated state) ".

In this case, the "Setup" message includes a call reference, various information elements (eg, called part number) required for call processing, user cell speed of the asynchronous transmission mode communication network, broadband bearer capability, and the like. , Quality of service parameters (QoS), etc.]. If there is no response for the time set by the timer T303, the " setup " message is retransmitted, and if there is no response even after a predetermined number of times, the call processing is stopped.

After the "Setup" message is received from the network 2, a valid connection identifier (VPCI / VCI) is selected and assigned, and then a "SETUP" message is transmitted to the called party 3 again, and then the "call procedure." (CALL PROCEEDING) "message is sent to the sender (1). At this time, when a "call procedure" message is input from the caller 1, the timer T303 is stopped, and after the timer T310 is started, the state of the outgoing call procedure is entered.

Then, after the "setup" message is received from the called party 3, the "CALL PROCEEDING" and "ALERTING" messages are transmitted to the network 2, and the alerting message from the network 2 is transmitted. When received, it is transmitted to the caller 1 and is in the state of "Call Delivered". Then, when the "alerting" message is received from the caller 1, the timer T303 or T310 is stopped, and the call is delivered.

Then, when a "CONNECT" message is generated so that the connection is allowed from the called party 3 and then transmitted to the network 2, the network 2 transmits it to the sender 1 and the "connect acknowledgment." (CONNECT ACK) "message to the called party 3 side, and receives a" connect acknowledgment "message from the sender (1).

Through the call processing process as described above, a communication path (connection) authorized by the connection identifier (VPCI / VCI) is formed between the caller 1 and the called party 2 so that data transmission and reception can be performed.

On the other hand, when the data transmission is terminated or in progress, the user (recipient or caller) who wants to release the connection generates a "RELEASE" message and starts the timer T 308 to request the release of the connection to the network. After that, it becomes a "Release Request state", and when the network receives a "release" message, the network releases the connection to the virtual channel, transmits a "release" message to the other party, and informs it of the "release request (RELEASE COMPLETE). Message is sent to the release request and is in the "NULL" state.

In addition, when the user (sender or called party) requesting the disconnection receives the "RELEASE COMPLETE" message, the timer T 308 is stopped, the virtual channel, the call number, etc. are released, and the "NULL" state is received. At this point, the user or network can generate a "STATUS ENQUIRY" message at any time to request information about the network or other user's status, and receive a "STATUS ENQUIRY" message. Or the network generates a "STATUS" message indicating its status.

8 illustrates a general format of a call processing control related message in a user network interface (UNI) of an asynchronous transmission mode communication network. Here, 1, ..., 8 at the top represent bits, and 1, 2, ... 9, etc. at the right side represent octets (bytes).

Here, the first octet is a protocol discriminator, Q.2931 is "0000,1001b", bits 8 to 5 of the second octet are "0000b", and bits 4 to 1 are call reference values. value) is expressed in octets and is typically "0011b".

The third to fifth octets indicate a call reference value. In particular, if bit 8 of the third octet is "0" as a call reference flag, a side for generating a call reference (usually, a caller side). Indicates a message to be sent from, and a " 1 " indicates a message to be sent to the party (usually the originator) that generates the call reference. If the call reference value is "0b", it represents a global call reference, and if it is "1b", it is a dummy call reference for a semi-permanent virtual channel connection (SPC). )

The sixth and seventh octets indicate message type related information, and the messages are classified according to the sixth octet value as shown in Table 5 below.

In addition, bit 8 of the seventh octet indicating message type related information is normally "1b" as an extension, bits 7 and 6 are "00b" as spares, and bit 5 is a message type flag (Flag). "0b" indicates that the Message instruction field is not important, and "1b" is followed by an explicit instruction.

And bits 4 and 3 are spares as "0b", bits 2 and 1 are message action indicators, and "00b" indicates a clear call, and "01b" indicates a spare. Discard and ignore, "10b" denotes Discard and report status, and "11b" denotes Reserved.

In addition, the eighth and ninth octets indicate a message length and may have a maximum length of 64K (2 ¹⁶ ) octets, and from the tenth octet (etc), an information element (IE) of variable length Follows.

FIG. 9 is a diagram illustrating a format of an end-to-end transmission delay information element of the information elements IE shown in FIG. 8. Here, 1, ..., 8 at the top represent bits, and 1, 2, 3, 4.5, 5.1, 5.2, 6, 6.1, 6.2, etc. on the right side represent octets (bytes).

In FIG. 9, the first octet is an information element identifier, and information elements are classified according to the values as shown in Table 6 below. The present invention relates to a received end-to-end transmission delay information element (EETD IE). Since it is for detection, it is checked whether the information element identifier (IE Id.) Of the first octet is "01000010b", that is, the end-to-end transmission delay information element identifier (EETD IE Id.).

The end-to-end delay information element (EETD IE) indicates a nominal maximum end-to-end transit delay (MEETD) that can be accepted on the basis of a call, and also by virtual channel access. It represents the cumulative transit delay (CTD) actually generated.

The transit delay means a one-way transmission delay of the user data transmitted between the sender and the called party, that is, during the data transmission step in the user plane, and the transmission delay includes the total processing time in the terminal user system, for example, processing. Time, AAL processing delay, ATM cell combining delay, and the like, and network transmission delays such as delivery delays, ATM layer transmission delays, and the like.

The cumulative transmission delay value (CTDV) indicated by the sender in the setup message includes a cumulative transit delay (CTD) from the sender to the network boundary.

Also, the Maximum End-to-End Transit Delay Value (MEETDV) is indicated by the originator requesting the end transmission delay for the call.

In addition, in the second octet, bit 8 is “1b” as an extension, bits 7 and 6 are coding standards, and bits 5 to 1 are information element instruction fields.

Herein, the coding standard is classified into four types according to bits 7 and 6 of the second octet, and in case of "00b", an ITU-T standard, and in case of "01b", an ISO / IEC standard and "10b". In the case of the National Standard, "11b" indicates the defined standard.

Bit 5 of the information element command field is a flag, "0b" means that the information element command field is not important, and "1b" means that an explicit command follows.

Bit 4 of the information element command field is a reserved bit and is used to indicate a "pass along request".

In addition, bits 3 to 1 of the information element command field are IE action indicators, for example, "000b" indicates a clear call, and "001b" indicates information element abandonment and processing (Discard). and Proceed), "010b" for information element message Discard, Proceed and Report Status, "101b" for Discard and Ignore, "110b" for message abandonment and status report (Discard) message, and report status).

The third and fourth octets indicate the length of the end-to-end transit delay contents (L).

The fifth octet represents a Cumulative Transit Delay Identifier (CTDI), the bit value of which is "00000001b", and the 5.1 octet and the 5.2 octet represent the Cumulative Transit Delay Value (CTDV). Indicates. At this time, the cumulative transmission delay value CTDV occupies a total of 16 bits. Bit 8 of the 5.1 octet is the most significant bit, and bit 1 of the 5.2 octet is the least significant bit.

The sixth octet represents the Maximum End-To-End Transit Delay Identifier (MEETI), and its bit value is "00000011b", and the 6.1-octet and 6.2 octets are the maximum end-to-end transmit delay identifier. (MEETDV: Maximum End-to-End Transit Delay Value) In this case, the maximum end-to-end transmission delay value MEETDV occupies a total of 16 bits. Bit 8 of the 6.1 octet is the most significant bit, and bit 1 of the 6.2 octet is the least significant bit.

First, we will briefly look at how end-to-end delay and jitter can be effectively guaranteed, such as the jitter adjustment service method, and then look at the proposed algorithm in detail.

In the jitter adjustment service method, a server is conceptually divided into two components, for example, a jitter adjuster and a scheduler. The jitter adjuster compensates for the distortion of traffic generated in the network, and the scheduler determines a service order among the distortion-compensated cells. Done. This functional separation allows delay limits to be flexibly allocated regardless of bandwidth, and greatly improves end-to-end jitter.

When the traffic is partially or totally reconfigured at each node so that the distortion of the traffic can be compensated for, the original traffic characteristic passes through the network without being greatly distorted. Therefore, the required buffer space can be reduced to save network resources, and the jitter characteristic of the transmitted traffic becomes good, thereby reducing the burden of jitter compensation processing on the receiving side.

In case of reconfiguring the characteristics of the traffic, the eligible time (ET) of the arriving cell is calculated, and the destination cell is temporarily stored in the jitter controller until the time is reached, and at the moment when the eligibility time is reached, Will print to the scheduler. In other words, the cell is not scheduled as soon as it arrives, but is considered as if the cell has not arrived by the cell's qualifying time.

The jitter regulator is divided into a cell rate jitter regulator and a delay jitter regulator by a method of calculating the eligibility time, which defines the eligibility time based on the distance from the previous cell, while the delay jitter regulator defines the The eligibility time is calculated based on the deadline to completely reconstruct the traffic.

On the other hand, in the scheduler, the service order is determined by the delay requirements so that each cell performs the service within the delay limit. The scheduling method is a first-in-first-out (FCFS) method, a static priority method, and a dynamic method. It is classified in a dynamic priority manner.

The first-in, first-out method is the simplest to implement, but only one delay limit is provided regardless of the type of traffic, making it difficult to use in various network characteristics, and the fixed priority method is fixed after dividing the traffic into different classes. Service will be provided at the priorities provided to provide the delay limits for each class. However, there is a limit to the efficiency that can be achieved since fixed priorities are always used regardless of network conditions.

In the dynamic priority method, priority is provided in units of cells, and then services are provided from the highest priority. This method is the most efficient, but it causes the hassle of sorting all the cells in the queue in order for the highest priority cell to be selected.

In general, all the non-working preservation algorithms can be interpreted by the jitter adjustment service method, and the jitter adjusters and schedulers adopted by the existing non-work preservation algorithm are listed in Table 7 below.

In general, the conventional jitter control service method is divided into two types according to the jitter control method, one of which is to control jitter by transmitting information related to scheduling to one node by using one section of the packet header. The other is a method in which jitter is adjusted by transmitting and exchanging cells in units of frames by a frame technique.

On the other hand, since there is no extra section to transmit scheduling related information in the ATM cell header, the first method cannot be applied to an asynchronous transmission mode communication network, but the second method can be used in an asynchronous transmission mode communication network, but there are various problems. Moreover, the efficiency is degraded by the coupling nature between delay limits and bandwidth allocation units, which are inherent by the adoption of the frame technique, and the problem can be alleviated to some extent if a layered frame technique is used, but still resolved. This is a difficult problem.

The following describes the method of transferring jitter information by interlocking counters in an asynchronous transmission mode communication network.

Therefore, in order for the jitter to be adjusted by the method of interlocking jitter information by the interlocking method of the counter, the node i in the network has a qualified time of the cell through interaction with the previous node i-1 regardless of the neighboring cells. To be defined. That is, it defines the eligible time as if the cell has experienced the maximum allowable delay, e.g., the size of the frame, at the previous node (i-1). And the qualified time of cell (k) in connection j for the node after the source node ( ) Is defined in the following equation (where i = 1, 2, ..., N).

Τ _i denotes a propagation delay between the previous node i-1 and node i, Denotes the frame size of connection j. Equation 1 shows that the qualified time of the k-th cell arriving at node i is determined by the previous node i-1 of the cell. This means that the previous node i-1 should output the qualified time information of the k-th cell to the node i. In the conventional method, the information is loaded on the header of the k-th cell.

However, the jitter information transfer method by the counter linkage can be known by itself as soon as the cell arrives at the node without having to send the information each time. That is, for connection j By operating the per-session counter (C _{i, j} ) to establish the relationship between ), The value of the counter is read out and immediately known. Thus, only one counter per connection can be used to know the virtual arrival times for all cells of the connection so that delay jitter can be effectively adjusted.

Therefore, each node has one counter per-session, and each counter is counted in slot units to define individual frames. The counter decrements the counter value by 1 for each slot, and is initialized again by the size value of the frame as soon as the counter value becomes "0". The counter is interlocked by accurately reflecting the transmission delay between neighboring nodes. That is, when the cell starting when the value of the counter in the previous node (i-1) is "c" arrives at the node (i), the value of the counter of the instant node (i) is also linked to "c", This is made possible by synchronizing the operation of the counter in the neighboring node upon accepting the connection.

The value of the counter has two meanings, which means the time remaining until the deadline for the cells in the scheduler and the time remaining until the qualified time for the cells in the jitter adjuster. Thereafter, as the value of the counter becomes "0", the service deadline of the cell in the scheduler becomes a service, and the cell in the scheduler must be serviced before the counter becomes "0".

For example, if a service is performed when the value of the counter is "3", then the cell is serviced before the 3 slots of the deadline, and when the cell arrives at the next node, the value of the counter at that time is "3". Cell will be stored in the jitter regulator for three slots. If it is stored for 3 slots in the jitter controller and then output to the scheduler, it is the same as having received the deadline service from the previous node and reaching the scheduler of this node.

FIG. 10 is a diagram illustrating an example of a method of transmitting jitter information by interlocking a counter in an asynchronous transmission mode communication network, and illustrates a case where a size of a frame transmitted is 10. FIG. As shown in FIG. 10, regardless of when a given cell is serviced by a previous node, a time point input to the scheduler of the next node is always constant, so that after all cells have experienced the maximum delay at the node, the service is performed. Is performed so that delay jitter is completely removed.

On the other hand, in the jitter information transfer method by the counter interworking method, although the packet size is small as in an asynchronous transmission mode communication network, it can be effectively applied to adjust jitter in a high speed communication network that does not support the transmission of scheduling related information. It is completely dependent on the operation of the counter once interlocked, so that the transmission delay can be used only in a synchronization network.

As described above, in the jitter information transfer method by counter interworking in an asynchronous transmission mode communication network, a cell is serviced using a frame for each connection, and a separate frame counter must be operated for each connection to define a frame for each connection of all connections. do. Therefore, in each node, one counter exists for each connection for each frame, and each counter counts in units of slots to define individual frames.

The counter decrements the value of the counter by 1 for each slot, and then initializes it back to the size of the frame as soon as the value of the counter becomes "0". In addition, the operation of the counter is interlocked by accurately reflecting the transmission delay between neighboring nodes. In this interlocking operation, the cell which started when the counter value at node i-1 of the frame counter is "c" is a node. The counter value at the moment of arrival at (i) is also linked to be "c". This is made possible by synchronizing the operation of the frame counter by sending information about the frame counter to neighboring nodes upon accepting the connection.

11 is a view illustrating the size of frames per connection (j, j ', j'') in a connection acceptance control method of a frame for each connection defined by counter interworking in an asynchronous transmission mode communication network according to the present invention. ). Here, the size of the frame for each connection (j, j ', j'') ( ) Is different for each definition.

12 is a diagram illustrating a call processing related message flow in the connection acceptance control method of a frame for each connection defined by a counter interworking in an asynchronous transmission mode communication network according to the present invention.

Meanwhile, asynchronous transmission from one terminal to another terminal connected to the network is performed by Q.2931, which is a call and connection control standard of a user network interface (UNI) of asynchronous transmission mode communication method. A method of using a connection-specific frame for real-time communication by mode communication method is as follows.

First, in the first step, a node that can accommodate the bandwidth and end-to-end delay limit required by a predetermined connection is selected by Q.2931, the call and connection control standard, and the path of the connection is determined. Frame size of the connection ( ).

In the third step, the frame counter is operated at the user network interface node of the called party terminal to operate the frame size ( After the frame of the connection is defined by the initial value of the frame counter), information about the frame of the connection is transmitted along the set path, and in the fourth step, the initial value and transmission of the frame counter from the third step are transmitted. The delay causes the value of the frame counter of the next node to be initialized.

Further, in the fifth step, when the value of the frame counter reaches from the calling terminal to the called terminal through every node, a frame for the connection is defined between the nodes, and then an acknowledgment signal (ACK) for the connection is sent to the calling terminal. After returning to the frame of the given connection is fully defined.

On the other hand, when a cell is serviced using a frame for each connection in an asynchronous transmission mode communication network, when a setting request is received for a predetermined connection j, the frame for connection is defined by defining a frame for each connection after a normal connection acceptance control process. I'm trying to. Therefore, for general non-real-time connections, connection acceptance control is performed in the conventional method. For each real-time connection, for example, real-time connections requiring strict quality of service (QOS) for delay and jitter, connection-specific frames are defined at each node. The transmission delay time information of the can be transmitted.

After that, when a connection establishment request is received from a predetermined caller, the connection acceptance control method operates as follows. First, when the path to the called party is established by the routing method, a node that can allow the bandwidth required by the connection is usually selected.

At this time, if the bandwidth requested by the connection cannot be accepted by at least one node on the path to the called party, the connection acceptance request of the connection is not accepted. In addition, if each node in the path allows the bandwidth requested by the connection, an allocable delay limit for that bandwidth is calculated and sent to the destination node. Here, each node performs a scheduling availability test along with a bandwidth availability test, which is performed to detect a schedule saturation state. This is because the saturation occurs even when the bandwidth is not exceeded.

Meanwhile, the called party node can determine whether a predetermined connection can be established by summing up delay limits that can be guaranteed by each node and comparing the end-to-end delay limits required by the user. In this case, when it is determined that the predetermined connection can be established, various parameters for the connection, for example, a value of a delay limit at each node are determined. Then, the determined value is informed to all nodes on the path, indicating that the connection establishment request has been accepted for the connection.

On the other hand, in the present embodiment, the connection acceptance control method of the frame for each connection defined by the counter interworking in the asynchronous transmission mode communication network is largely composed of two stages. The first stage corresponds to the existing connection acceptance control process. Algorithm routing, in which a node is selected that can accommodate both the bandwidth and end-to-end delay limits required by the connection.

The second step defines a frame of the connection along the path set to be performed after the path is established. ) Is determined first, and the operation of the frame counter is interlocked by accurately reflecting the transmission delay from each node to the neighboring node.

Each node operates a frame counter to define a frame of the connection, and simultaneously sends frame size and initial value information of the frame counter to the next node on the path. And, the initial value information of the frame is the frame counter value of the node at the moment the cell is sent, and when the next node receives the cell, it initializes the node's frame counter in consideration of the initial value information and the transmission delay.

13 is a view showing the operation of the frame counter in the connection acceptance control method of the frame for each connection defined by the counter interlocking in the asynchronous transmission mode communication network according to the present invention.

Meanwhile, the frame start time of the predetermined connection j is determined by the predetermined node i. , The frame start time of connection j on node i + 1 Then, Equation 2 below is established.

here, Denotes the transmission delay between node i and node i + 1, Denotes the delay caused by slot mismatches when the cell sent from node i arrives at node i + 1, Will be satisfied.

For example, if a cell is transmitted when a value of a frame counter is "c" at a predetermined node i, the cell is timed. Will reach node i + 1. Therefore, in order to match the frame boundary at node i + 1 with the frame boundary at node i, the frame counter of node i is set to the first slot (i.e. ) Must be initialized to "c". After the frame counter is initialized in this manner, the frame counter is decremented by 1 every slot, and then the size of the frame is re-entered as soon as the counter value becomes "0". Will be initialized to

When the value of the frame counter reaches the destination node through every node, the frame for the connection is completely defined between neighboring nodes. After that, the frame counter returns to the source node and informs that the frame of the connection is completely defined.

Explained above

Claims (6)

Asynchronous transmission mode communication from one terminal to the other terminal connected to the network by Q.2931, which is a call and connection control standard of a user network interface (UNI) of the asynchronous transmission mode communication method In the method for using the connection-specific frame for real-time communication by way, Q.2931, the call and connection control standard, a first step of selecting a node that can accommodate the bandwidth and end-to-end delay limit required by a predetermined connection and establishing a connection; Frame size of a given connection Determining a second step; The frame counter is operated at a user network interface node of a called party terminal, so that A third step of transmitting information about the frame of the connection along the established path after the frame of the connection is defined by the initial value of the frame counter; A fourth step of initializing the value of the frame counter of the next node by the initial value of the frame counter and the transmission delay from the third step; When the value of the frame counter reaches from the calling terminal to the called terminal through every node, a frame for the connection is defined between the nodes, and then the acknowledgment signal (ACK) for the connection is returned to the calling terminal. The admission control method for a real-time connection using a frame for each connection in an asynchronous transmission mode communication network, characterized in that the frame of the connection is completely defined. The method according to claim 1, wherein the start time of a frame of a predetermined connection j at the predetermined node i + 1 ( ) Is the frame start time from the previous node ( )and Admission control method for a real-time connection using a frame for each connection in an asynchronous transmission mode communication network, characterized in that the setting so that the relationship. 3. The method of claim 2, wherein the arrival time of the cell at the predetermined node i + 1 during transmission when the predetermined cell at the predetermined connection j is the value of the frame counter at the predetermined node i is "c". Admission control method for a real-time connection using the frame for each connection in the asynchronous transmission mode communication network, characterized in that the setting to be. 4. The time period of claim 3, wherein the value of the frame counter of node i is the first slot after cell arrival so that the frame boundary at node i + 1 matches the frame boundary at node i. Admission control method for a real-time connection using a frame for each connection in the asynchronous transmission mode communication network, characterized in that to be initialized to "c". 5. The method according to claim 4, wherein after the value of the frame counter is initialized, the frame size decreases by "1" every slot and becomes "0" again. Admission control method for a real-time connection using a frame for each connection in the asynchronous transmission mode communication network, characterized in that the initialization to. The method of claim 1, wherein the initialization value transmitted to the next node is a value of a frame counter at the moment when a predetermined cell is sent from a predetermined node. Admission Control Method.