KR19990050444A - How to control egg information in communication system - Google Patents

Abstract

The present invention relates to a method for controlling RAU information in a communication system for transferring data between a master node and slave nodes. Its purpose is to propose a bandwidth allocation method and a frame format for the ATM-PON-based point-to-multipoint topology communication system that is being standardized by the ITU-T and the ATM Forum, which are being standardized. The present invention provides a method of controlling RAU information of a communication system that maximizes bandwidth utilization and minimizes data transmission delay waiting for transmission in each buffer of slaves to satisfy the highest quality of service (QoS). Its features include a first step in which the master node designates as many RAU grants as needed from among a given number of grants in the downward direction, and the grant designating which slaves should use which slots and which information should be transferred. In the second step, the slaves analyze each grant subfield to check whether the corresponding grant belongs to them, and then transfer the information to the master through the uplink slot. The effect is to achieve the maximum quality of service (QoS) by maximizing the bandwidth utilization within the limited bandwidth and minimizing the data transmission delay waiting for transmission in each buffer of slaves.

Description

How to control egg information in communication system

The present invention relates to a method for controlling RAU information in a communication system, and more particularly, to a method for controlling RAU information in a communication system for transferring data between a master node and slave nodes.

In general, in asynchronous transfer mode-passive optic network (ATM-PON) communication system in which one master node and multiple slave nodes communicate using a single medium, slave nodes are time-division multiple access. Division Multiple Access (hereinafter, abbreviated as TDMA) is used to access the common media to transfer data. A data transfer method and a frame structure therefor have been developed between a master node controlling such access and slave nodes accessing a shared medium by access control thereof.

In a conventional communication system having a point-to-multipoint topology, only a fixed bandwidth can be used for data transmission, thereby preventing dynamic bandwidth allocation problems. It allocates bandwidth as the amount of information to change from time to time and yields to other users for unused bands maximizes overall bandwidth utilization. By using the STM (Synchronous Transfer Mode) method, the dynamic bandwidth allocation function is unnecessary. However, in the process of integrating data transmission units of all communication networks into ATM cells, in the point-to-multipoint communication method using ATM cells as a unit, such dynamic bandwidth allocation becomes the maximum variable that satisfies the performance and quality of service of the network. . Of course, the ATM cell may be transmitted in the STM scheme, but this causes a waste of bandwidth because it is necessary to allocate more bandwidth than necessary.

The present invention devised to solve the above problems is a band allocation method applicable to the ATM-PON type point-to-multipoint topology communication system that is being standardized by the ITU-T and the ATM Forum, the world standardization organization, and the frame therefor. RAU information control method of communication system that satisfies the highest quality of service by minimizing data transmission delay waiting for transmission in each buffer of slaves by suggesting format to get maximum bandwidth utilization within limited bandwidth The purpose is to provide.

A feature of the present invention to achieve the above object is a first step in which a master node designates as many RAU grants as necessary from a predetermined number of grants in a downward direction, and which grants should be used by which slaves and which slots. A second step of designating whether information should be delivered, and a third step of slaves analyzing each grant subfield to determine whether the grant corresponds to them and delivering the specified information type to the master through an upward slot. There is. Here, in the first step, the grant determines what kind of information of a slot to which any slave is assigned. Of course, the information includes user ATM cell, PLOAM cell, IDLE cell and RAU information.

Another feature of the present invention for achieving the above object is a step in which a master node designates any one grant from a predetermined number of grants in a downward direction, and a predetermined subfield among the slaves is a subslot of a slot of an upward frame. The RAU information is inserted into the master and delivered to the master.

Another feature of the present invention for achieving the above object is the step of specifying a plurality of grants each master node can allocate a slot of a size that can include the entire slaves from a predetermined number of grants in the downward direction and each slave In order to deliver RAU information to subslots of corresponding slots in order. Here, in the designation step, grants are specified differently according to the size of the RAU information.

1 is an application of the present invention.

2 is a diagram illustrating an up-down frame format of the ATM-PON method.

3 is a diagram illustrating a PLOAM cell format of an ATM-PON scheme.

4 illustrates a frame format for point-to-point RAU control.

5 illustrates a frame format for point-to-multipoint RAU control.

6 illustrates a frame format for broadcasting RAU control.

The present invention provides an information transfer method necessary for allocating a dynamic band in an ATM-PON based communication system in which communication between a master node and multiple slave nodes is performed in a TDMA manner using a single medium. Contains the frame format for the.

Under a communication environment consisting of one master node and several slave nodes, when a network connection between them is made up of one single medium, that is, in a communication system having a point to multipoint topology, access of shared media between the slaves is prevented. The MAC (Media Access Control) function and its dynamic operation are key factors in determining the performance of the network. This MAC function and dynamic band management require frequent information exchange between the master and each slave node and the most appropriate frame format should be defined. That is, each slave node must continuously transmit the amount of information buffered by its own node to the master node to be allocated an additional band (which is used as a slot here). This additional bandwidth allocation requirement is not arbitrarily made by the slave without control of the master node in a communication system based on ATM PON, which is currently defined by the World Standards Organization such as the ATM Forum or ITU-T. This is because the master node either counts the number of ATM cells delivered from each slave node periodically, or polls the slaves by a value defined in proportion to the value of the band defined at connection establishment. This requires additional bandwidth requirements of the slaves. To this end, the present invention proposes three methods in which a master node polls slaves and a frame format in which slaves require additional band allocation accordingly.

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

1 is an application of the present invention. The application of the present invention will be described with reference to FIG.

The communication method of the ATM-PON system composed of one master 11 and several slaves 12 to 1N is schematically shown. The master 11 (also called OLT (Optical Line Terminator)) broadcasts data to multiple slaves (also called optical network units (ONUs)) by a time division multiplexing (hereinafter referred to as TDM) method. Broadcasting, each slave extracts only the information in its allowed band. In addition, the slaves can only transmit data to the slot designated by the master. 'Master Tx Frame generation and Grant allocation unit' of the master 11 generates a frame composed of 56 time slots by 53 bytes when the line rate is 155.52 Mb / s, and 53 bytes by 622.08 Mb / s. Generate a frame consisting of 224 time slots. One ATM cell allocated to each slot is delivered to one, several, or all slave nodes by VPI / VCI value. At this time, the E / O converts the electrical signal into an optical signal and the WDM element transmits data at the wavelength λ1. The transmitted optical signal is delivered to N slave nodes in the optical splitter. Each slave node extracts an optical signal having a wavelength [lambda] 1 through a WDM device and converts the optical signal into an electrical signal through an O / E (optical / electrical conversion device). The slaves analyze the VPI / VCIs of an ATM cell every slot to extract an ATM cell with a number that matches its own (called ONU Id or PON Id). In addition, the slaves transmit data using the wavelength lambda 2 only to the slot designated by the master, and the data transmitted from each slave is transmitted to the master through the optical splitter. The slaves insert user information (user ATM cell) or RAU (Request Access Unit) information into corresponding slots of the frame under the control of the master. RAU information communicates its buffering status to the master node so that if more bandwidth is needed, i.e., the buffering depth of its own node is above the threshold and can cause overflow. Used to request an allocation. The master extracts user information and RAU information by analyzing data of each slot of the delivered frame.

2 is a diagram illustrating a vertical frame format of the ATM-PON method. The up-down frame format of the ATM-PON method will be described with reference to FIG. 2.

This shows the structure of the frame delivered from the master to each slave (called Downstream). (21) shows the downlink frame format when the line rate is 622.08 Mb / s. Here, the first ATM cell of the frame becomes a PLOAM (Physical Layer Operation & Maintenance) cell, and every 27 cells occupy a fixed position of eight PLAOM cells in one frame. (22) shows the downward frame format when the line speed is 155.52 Mb / s. Here, the first ATM cell of the frame becomes a PLOAM (Physical Layer Operation & Maintenance) cell, and every 27 cells occupy a fixed position of two PLAOM cells in one frame. (23) shows the frame format transmitted from each of the slaves to the master when the line rate is 155.52 Mb / s (this is called an upstream). The uplink frame consists of 53 time slots of 56 bytes each. Control of which slave carries information in which slot is transmitted is performed by downlink PLOAM cell information.

3 is a diagram illustrating a PLOAM cell format of the ATM-PON method. A PLOAM cell format of the ATM-PON method will be described with reference to FIG. 3.

This shows the format of the PLOAM cell for each direction. (31) shows the format of the downlink PLOAM cell. The location of the downlink PLOAM cell is broadcast to all slaves using the predefined location as shown in (21). There are many different functions of the PLOAM cell, but only the functions related to band allocation are described here. The master broadcasts to the slaves the information in the grant subfield that decides which slave to use each slot of each frame in the upstream in the first and second PLOAM cells of each frame. 27 grants are delivered to the first PLOAM cell and 26 grants are delivered to the second PLOAM cell. These 56 grants designate a user for the uplink 56 time slots. (32) shows the format of the upward PLOAM cell. The uplink PLOAM cell does not have a band request field defined that requires an additional band other than the band allocated when establishing the ATM connection. This is because ATM communication is based on asynchronous transmissions, so that at any time there may be more than just the bandwidth allocated to the slave nodes. If slave nodes always transmit data only by the bandwidth at connection establishment, the slave nodes must perform a very large buffering function. However, the cell transmission delay caused by this buffering function is the biggest cause of degrading the quality of communication service. Therefore, when the amount of data to be transmitted from a slave increases, an additional instantaneous band is allocated to satisfy the minimum communication quality of service, which is a very important function in an ATM-PON system. For this purpose, an additional bandwidth allocation request scheme of the current RAU (Request Access Unit) concept is needed. 33 shows one possible example of the RAU. That is, (GT + PM + DL) represents the same overhead as the existing uplink ATM cell, and PON Id (PON Identification) represents the slave number that transmitted the RAU. The Ident subfield is used to distinguish the duplicated slaves.P-queue (Priority queue depth) represents the depth of the priority buffer and N-queue (Normal queue depth) represents the depth of the buffer with normal priority. . The cyclic redundancy check (CRC) subfield is error detection information for bytes excluding overhead.

4 is a diagram illustrating a frame format for point-to-point RAU control. A frame format for point-to-point RAU control will be described with reference to FIG. 4.

This is one of the overall configuration of the present invention shows that the master and one slave delivers the RAU by the point-to-point RAU delivery method. The master node assigns as many RAU grants as needed out of the 53 random grants in the downward direction. In other words, the grant determines what kind of information a given slave will deliver. The information becomes a user ATM cell, a PLOAM cell, an IDLE cell, and RAU information proposed by the present invention. Thus, grant specifies which slave should use which slot and what information should be passed. Therefore, the slaves analyze each grant subfield to confirm that the grant corresponds to them, and transmit the information to the master through the uplink slot. (41) instructs any one slave to transmit the RAU using point-to-point RAU delivery in grant subfield 8 (i.e., the ninth slot), and in the uplink frame of (42), Shows that one RAU is delivered to the ninth slot. At this time, 53 grants can be designated for RAU as many grants as necessary by the master.

5 is a diagram illustrating a frame format for point-to-multipoint RAU control. A frame format for point-to-multipoint RAU control will be described with reference to FIG. 5.

This is one of the overall configuration of the present invention, it shows that the master and several slaves deliver the RAU by the point-to-multipoint RAU delivery method. The master node assigns any one grant among the 53 grants downward to a value called 'multi', and sets the PON Id (PON Identification: each slave or multiple slaves) to 'multi'. 'Is specified. In addition, Msg. By specifying Id (Message Identification) (which indicates the type of message subfield) as 'grant', it indicates that the current message content indicates the Id (Identification) of the slave for the point-to-multipoint RAU delivery method. At this time, the value of the ten message subfields represents a maximum of ten slave addresses. In the downward frame format of (51), the grant subfield 1 (ie, the second grant) is designated as 'multi', the PON Id subfield is designated as 'multi', and the Msg. It shows Id as 'grant', Msg.0 as 'onu1', Msg1 as 'onu3', and Msg.6 as 'onu9'. In (52), among the slaves interpreting these frames, onu1, onu3, and onu9 insert RAU information into the first, second, and seventh subslots in which the second slot of the uplink frame is divided into up to 10 equal parts, and delivered to the master. Show the orientation frame structure.

6 illustrates a frame format for broadcasting RAU control. A frame format for broadcasting RAU control will be described with reference to FIG. 6.

This is one of the overall configuration of the present invention shows that the master and the entire slaves deliver the RAU by the broadcasting RAU delivery method. The master node designates a number of grants that can allocate a slot having a size that can include all slaves among the 53 grants as a value called 'broad'. How many grants should be defined as 'broad' depends on the size of the RAU information. In the downlink frame format of 61, the size of the RAU is assumed to be 8 bytes including the overhead. In this case, as shown in (62), since the size of one slot is 56 bytes, one slot includes seven RAU information. In addition, when there are 56 total slaves, eight slots are required. These eight slots designate any eight grants as 'broad', as in (61).

As described above, the present invention proposes a band allocation method and a frame format that can be applied to an ATM-PON type point-to-multipoint topology communication system that is being standardized by ITU-T and ATM Forum. It is effective in bringing out maximum bandwidth usage within a limited bandwidth and minimizing data transmission delay waiting for transmission in each buffer of slaves to satisfy the highest quality of service (QoS).

Claims (6)

A first step of the master node designating as many RAU grants as necessary from among a predetermined number of grants in a downward direction; A second step in which the grant specifies which slave should use which slot and what information to convey; And Slave analyzes each grant subfield to determine whether the corresponding grant corresponds to the third step, and transmits the information to the master through the uplink slot, the point-to-point RAU information control method . The method of claim 1, In the first step, And the grant determines what kind of information of a given slot is transmitted by any slave. The method of claim 2, And the information is user ATM cell, PLOAM cell, IDLE cell and RAU information. Specifying, by the master node, any one of a predetermined number of grants in a downward direction; And And a predetermined subfield among the slaves inserts the RAU information into the subslot of the slot of the uplink frame and transmits the RAU information to the master. Designating, by the master node, a plurality of grants capable of allocating slots having a size that can include all slaves from a predetermined number of grants in a downward direction; And And transmitting slave RAU information sequentially to subslots of corresponding slots. The method of claim 5, The point-to-point RAU information control method characterized in that the granting step in accordance with the size of the RAU information in the designation step.