KR101663181B1 - Multicast service performance improving method for G.hn applied FTTdp access network - Google Patents

Abstract

The present invention relates to a method to improve multicast service performance of an FTTdp subscriber network to which a G.hn technology is applied to extend a multicast service providing distance and to improve performance by retransmitting a damaged packet in the occurrence of damage to a multicast packet generated by the performance limitation of a copper line bundle according to an in-house wiring environment when a high speed communication over gigabit is provided by applying the G.hn technology for the home network to a telephone subscriber network. The method can generate an error corresponding to a corresponding identification number and to intentionally restore by generating a value in which an identification number changed along the appointed pattern is added when an error confirmation code (for example, CRC) is generated for a packet transmitted from a port of line collecting equipment; uses an identifier to classify an identification number corresponding to intentional errors when the intentional errors in the received terminal (CPE) maintains an appointed pattern along with the order of a transmission packet; and can specify the packet of a multicast method without changing a communication frame required to reduce compatibility with a configuration to generate and analyze a non-standard communication frame. The method has an effect to improve a reception performance by the retransmission of a packet including errors and to extend a reception distance.

Description

{Multicast service performance improving method for G.hn applied FTTdp access network}

The present invention relates to a method for improving multicast service performance of an FTTdp (Fiber To The Distribution Point) subscriber network to which G.hn technology is applied, and more particularly to a G.hn technology for a home network, It is possible to retransmit a damaged packet when a multicast packet is damaged due to a performance limitation of a copper wire bundle providing a plurality of domestic wiring environments, and to improve the performance of multicast service of FTTdp subscriber network with .hn technology.

Due to the rapid development of various communication technologies and terminals, network services are also being developed to meet the demand for high quality and high capacity multimedia contents.

Therefore, the internet environment is also upgrading to a service environment of 1 Gbps exceeding several hundred Mbps.

Currently, gigabit internet services are based on the case where the domestic wiring environment of apartment houses or single houses is composed of optical cables and UTP lines. In the case where the wiring environment is a copper wiring such as a telephone line or a coaxial cable, New technologies are being researched.

G.hn is a general technical name for home network technology that has been complicated by related organizations including G.996x of ITU-T (International Telecommunication Union-Telecommunication Standardization Sector). It uses existing copper physical medium such as telephone line, power line and coaxial cable To provide a data transmission rate of 1 Gbps or more.

For example, in the case of a communication technology using a telephone line, the ADSL technology that provides a transmission rate of 512 kbps using the 25 kHz to 1.1 MHz band has developed to VDSL2 technology that provides a transmission speed of 200 Mbps using the 25 kHz to 30 MHz band, Is not provided. On the other hand, ITU-T G.996x standard recommendation using a telephone line, G.hn, a high-speed subscriber network technology, can provide a transmission speed of 1 Gbps using a wide band of 2 to 100 MHz. Recently, Research is also being done to double it.

This G.hn technology basically uses OFDM modulation and time division half duplex transmission using a sub-carrier of an appropriate band depending on the medium. For example, in the case of a telephone line, a transmission rate of 1 Gbps is implemented in a 100 MHz band using 2048 subcarriers of 48.828125 kHz band, and a method of using 4096 subcarriers by extending the used band to 200 MHz is also introduced.

If the G.hn technology is applied to the subscriber network, it is possible to connect the building to the premises through an optical line, and to apply the G.hn technology to the already-wired telephone line inside the building, Wire (Gigawire) technology has emerged.

However, due to the characteristics of the existing telephone line wiring system, crosstalk is inevitable in that dozens to hundreds of telephone line pairs are composed of bundles, so that a signal transmitted / received through an adjacent telephone line flows and crosstalk occurs. Especially, since the effect of near end cross talk (NEXT) generated in the vicinity of each port of the central office (CO) for providing G.hn technology can not be neglected, There is a problem that the quality of service provided through this is lowered.

In the subscriber network using G.hn technology, the aggregation equipment is connected to the customer premises equipment (CPE) connected to each port through a copper line, thereby providing a data communication service and a multimedia broadcasting service, The bandwidth required for this is continuously increasing. In particular, a multimedia broadcasting service such as IPTV (Internet Protocol Television) provides not only HD (High Definition) resolution video but also UHD (Ultra High Definition) video of 4K or more corresponding to such HD video It is expected that 8K HD video will be provided in the future. In the case of 8K HD video, the bandwidth for IPTV reaches 100 ~ 120Mbps, so a bandwidth of several hundred mega-bits is needed for stable service.

Typical data communication services use a unicast method. Typically, TCP (Transmission Control Protocol) is used. Because it has a function to retransmit an erroneous packet through 3-way handshaking, instantaneous deterioration of the line environment Is insensitive to. However, because multimedia service uses multicast method and most of it uses UDP (User Datagram Protocol), it is transmitted only in one direction without handshaking. Therefore, when transmission packet is damaged due to deterioration of the instantaneous line environment, it can not be restored. In particular, in the case of a UDP packet, since there is no means for identifying a received packet, even if an error occurs in the packet, it is impossible to apply the configuration for specifying the packet and retransmitting the packet to the transmitting side.

If there is no serious problem if there is some data corruption in the multiplex transmission of multimedia data that is audible and humanly verified by human beings, it is not a big problem. Therefore, even though there is a possibility that some packets may be damaged, However, in the current environment in which video data is transmitted in a compressed manner for a high-quality moving image service, serious quality degradation may occur due to some packet damage. For example, when a key frame that is a reference in the image compression method is damaged, the compressed key frame continuously affects other compressed frames based on the key frame.

Particularly, in case of G.hn based subscriber network which is intended to perform high-speed communication using copper line, on / off of neighboring port, long line distance, excessive traffic occurs in neighboring port, , There is a problem in that when the large-capacity data is downloaded along with the reception of the multimedia broadcasting service, the external quality of the weather is changed such as rainfall or lightning, and the cable is used for some services such as VDSL or ADSL. The actual available bandwidth is significantly lower than the peak bandwidth, and the multicast service, which can not recover the damaged packet, has a problem that the serviceable distance is short and the service quality is low.

Korean Patent No. 10-1403590 [Title of the invention: Method for applying G.hn technology to an access network]

An object of the present invention to solve such problems is to provide an error checking code (for example, a CRC code) for a frame to be transmitted from a port of a central office (CO) of a fiber to the distribution point (FTTdp) : cyclical redundancy check) is generated, a value obtained by adding an identification number changed according to an already-promised pattern is generated as a target, so that an error corresponding to the identification number is generated when the target is intentionally restored, In a CPE (Customer Premises Equipment), when the intentional error maintains a promised pattern according to the order of transmitted packets, an identification number corresponding to an intentional error is used as an identifier for packet classification, Which can improve the reception performance by retransmitting the error packet by making it possible to identify the packet even when the G.hn technique is applied And a method for improving the multicast service performance of the TTdp subscriber network.

It is another object of the present invention to provide a method and system for generating an error check code reflecting an identifier for each port of a concentrator, generating a transmission frame, backing up transmission frames (packets) of a predetermined size while identifying packets of each frame using the identifier, Upon receiving the retransmission request identifier, the packet is retransmitted, and the terminal arranges the reception order of retransmitted packets by rearranging the received packet queues, thereby improving the performance of receiving the multicast packet, The present invention provides a method for improving the multicast service performance of the FTTdp subscriber network to which the G.hn technology is applied so that it can be greatly extended and reliability can be enhanced.

A method for improving multicast service performance of an FTTdp (Fiber To The Distribution Point) subscriber network to which G.hn technology is applied according to an embodiment of the present invention includes a plurality of CPEs (Customer Premises Equipment) A method for improving the multicast service performance of a subscriber network to which G.hn technology is applied, the method comprising: a central office (CO) having a plurality of ports connected to a home line; An error check code generation step of adding an identification number so that an error value corresponding to the identification number is calculated in the error check code verification process when generating the check code; A transmitting step of a collecting device transmitting a packet including an identification number to a terminal through a transmission packet queue in a multicast manner; A receiving step of verifying an error check code of a received packet while storing a packet received by the terminal in a received packet queue in a multicast manner and calculating an identification number corresponding to the error; A retransmission request step of requesting retransmission of a packet having an identification number corresponding to the received packet to a concentrator when it is determined that the received packet is damaged when the identification number calculated in the reception step is out of a predetermined pattern; And a retransmission step of retransmitting the packet corresponding to the identification number to the terminal when the aggregation equipment receives a packet retransmission request from the terminal.

When the terminal receives the retransmitted packet from the concentrator, reordering the packets of the received packet queue based on the identification number of the received packets.

The error check code generation step, the transmission step, and the retransmission step are performed for each port of the aggregation equipment.

The transmitting step may further include temporarily storing the packets stored in the transmission packet queue in a backup queue having a predetermined size, and the retransmitting step selects the retransmission request packet from the backup queue based on the identification number and retransmits .

The error checking code generating step may include changing the identification number according to a predetermined pattern according to the packet order, and the identification number may be a unique value for each packet received in the received packet queue.

The promised pattern may be a sequentially increasing or decreasing number of n bits in size.

The error check code may be a CRC (Cyclical Redundancy Check).

In addition, it is possible to adaptively adjust the sizes of the transmission packet queue and the reception packet queue according to the frequency of the packet retransmission request.

In addition, the aggregator adds a VLAN tag to the frame for packet transmission and inserts information for verifying the identification number included in the error check code or information identifying the packet according to the retransmission request in the corresponding VLAN tag have.

The method for improving the multicast service performance of the FTTdp subscriber network to which the G.hn technology is applied according to the embodiment of the present invention is characterized in that when an error check code (for example, CRC) is generated for a packet to be transmitted from a port of a concentrator, And an error corresponding to the identification number is generated when the terminal is intentionally restored, and the intentional error is transmitted from the terminal (CPE) It is possible to use an identification number corresponding to an intentional error as an identifier for identifying a packet, so that a configuration for generation and analysis of a non-standard communication frame and a communication frame change requiring a reduction in compatibility are required It is possible to specify a multicast type packet and to improve reception performance by retransmission of an error occurrence packet It is possible to extend the new distance.

Also, in the multicast service performance improvement method of the FTTdp subscriber network to which the G.hn technology is applied according to the embodiment of the present invention, an error check code reflecting an identifier for each port of the aggregation equipment is generated to generate a transmission packet, When receiving a retransmission request identifier from a terminal, the packet is quickly retransmitted, and the terminal retransmits the retransmitted packet through the reordering of the received packet queue based on the identifier It is possible to improve the performance of multicast packet reception, thereby greatly extending the multicast service providing distance and improving the quality.

Also, the multicast service performance improvement method of the FTTdp subscriber network to which the G.hn technology is applied according to the embodiment of the present invention causes an intentional error corresponding to the identification number when generating the error check code, It is possible to verify the normal reception by confirming that the identification number according to the intended error obtained from the error check code of the received packet conforms to the promised pattern, and at the same time, the identification number of the corresponding packet can be verified. There is an effect that a plurality of functions are performed using CRC of the same size.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating a general telephone line-based subscriber network. FIG.
FIG. 2 is a block diagram showing a configuration of a subscriber network employing G.hn technology. FIG.
3 is a conceptual diagram illustrating a problem caused by packet corruption that may occur in a multicast service of a subscriber network applying G.hn technology.
4 is a simple communication frame structure diagram.
5 is a configuration diagram of a multicast service performance improvement system of a subscriber network applying G.hn technology according to an embodiment of the present invention.
6 to 9 are conceptual diagrams for explaining an operation method of a multicast service performance improvement system of a subscriber network applying G.hn technology according to an embodiment of the present invention.
10 is a conceptual diagram illustrating an operation method according to an embodiment of the present invention.
11 is a flowchart illustrating a multicast service process of a subscriber network to which G.hn technology is applied according to an embodiment of the present invention.

It is noted that the technical terms used in the present invention are used only to describe specific embodiments and are not intended to limit the present invention. In addition, the technical terms used in the present invention should be construed in a sense generally understood by a person having ordinary skill in the art to which the present invention belongs, unless otherwise defined in the present invention, and an overly comprehensive It should not be construed as meaning or overly reduced. In addition, when a technical term used in the present invention is an erroneous technical term that does not accurately express the concept of the present invention, it should be understood that technical terms that can be understood by a person skilled in the art can be properly understood. In addition, the general terms used in the present invention should be interpreted according to a predefined or context, and should not be construed as being excessively reduced.

Furthermore, the singular expressions used in the present invention include plural expressions unless the context clearly dictates otherwise. The term "comprising" or "comprising" or the like in the present invention should not be construed as necessarily including the various elements or steps described in the invention, Or may include additional components or steps.

In addition, terms including ordinals such as first, second, etc. used in the present invention can be used to describe elements, but the elements should not be limited by terms. Terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein like reference numerals refer to like or similar elements throughout the several views, and redundant description thereof will be omitted.

In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. It is to be noted that the accompanying drawings are only for the purpose of facilitating understanding of the present invention, and should not be construed as limiting the scope of the present invention with reference to the accompanying drawings.

In the description of the present invention, terms such as a packet and a frame are used. However, the present invention is not limited to the specific meaning on the transport layer, and the technical principle of the present invention can be applied If so, the application of the technology as a specific layer is not limited.

In addition, in describing the present invention, a central office (CO), a port, and a customer premises equipment (CPE) may be referred to as another term GAM (G.hn Access Multiplexer ), Domain master (DM: Domain Master), and GNT (G.hn Network Terminal) / EP (End Pointer).

The present invention relates to a method for improving multicast service performance of a subscriber network basically applying G.hn technology, and more particularly, to a method for improving multicast service performance of a subscriber network employing G.hn technology, in which a multicast method (more specifically, UDP) The present invention relates to a multicast service performance improving method capable of retransmitting an error occurrence packet by allowing each packet to be identified without changing the packet standard in the packet.

FIG. 1 is a block diagram illustrating a general telephone line based subscriber line network, and illustrates an xDSL subscriber network as an example.

(CO: Central) having a switching device (packet switching device) 21 for connecting a plurality of ports 22 to an external network (a matro network, a backbone network, an Internet network, etc.) A customer premises equipment (CPE) 41 connected to each port 22 of the concentrator 20 and a terminal 41 connected to the concentrator 20, And a telephone line 31 to 33 for connection.

The home office 40 includes a hub 42 connected to the terminal 41 to enable connection of various data communication terminals (PC, set-top box, IPTV, etc.) Telephone service can be used as is.

In the case of such a general telephone line-based subscriber network, the concentrator 20 is mostly located on the network service operator side and the terminal 41 is located in the house.

Meanwhile, the conventional telephone line-based subscriber line uses a telephone line that has already been constructed with in-house wiring, and a telephone line connected to the concentrator 20 has dozens or hundreds of pairs of telephone line bundles. Particularly, in the case of a distribution network for distributing telephone lines to each household constructed in a building (apartment or building) 50, dozens of pairs of telephone lines are vertically arranged and horizontally branched for each household.

Although the existing xDSL-based subscriber network provides a transmission rate of about 200Mbps, it is not enough to cope with the recent high-quality high-definition multimedia service.

FIG. 2 is a diagram showing a configuration of a FTTdp (Fiber To The Distribution Point) subscriber network employing the G.hn technology. In recent years, a Giga wire (G.992x) Giga Wire).

In other words, unlike the existing collective equipments of the copper wire-based (telephone network, cable network) subscriber network are configured on the network service provider side, the aggregation equipment 100 is arranged in the premises of the collective building 50, The concentrator 100 and the network service provider are connected by an optical cable so that the existing copper wire medium can be used for high-speed communication at a short distance inside the building. This configuration can be utilized as a terminal configuration of the FTTdp subscriber network.

In the G.hn technology, each port of the concentrator 100 is referred to as a domain master (DM) 130, the terminal is referred to as an end point (EP) 46, G.hn domain. This is a term for distinguishing ports and terminals supporting G.hn technology, and refers to ports and terminals supporting G.hn technology in a comprehensive sense.

In addition, in the Giga wire which is recently approved as a domestic standard, the concentrator 100 is referred to as a G.hn Access Multiplexer (GAM) and the terminal is referred to as a GNT (G.hn Network Terminal) 45.

The illustrated concentrator 100 plays a role of G.hn's Global Master and controls the GAM Manager 110 that adjusts the settings of the domain master 130 to reduce the interference of each G.hn domain .

As shown in the example of the structure of a subscriber network employing the G.hn technology shown in the drawing, a copper line, for example, a telephone line 31, 32, 33, which is already constituted by existing domestic wiring lines, 30, the telephone lines 31, 32, 33 connected to the respective domain master 130 are physically adjacent to each other.

Therefore, the inter-line crosstalk occurs in the domain master 130, and the bit error rate of the line also increases sharply as the distance increases. Therefore, a general multicast type service in which an error packet can not be restored has a short distance that can be provided, User complaints frequently occur.

Particularly, in the case of the FTTdp subscriber network to which the G.hn technology is applied, a method of improving the performance according to the crosstalk is used by various methods such as variable frame size allocation and frame retransmission according to the variation of the SNR value. However, due to the limitation of the bundle configuration using the copper line, on / off of the adjacent domain master, traffic change of the adjacent domain master, occurrence of failure of the adjacent domain master, use of excess traffic (downloading of large amount data during reception of multimedia broadcast) There is no way to overcome the packet loss in real time in case of sudden deterioration of line quality due to the change of the external environment such as the change of the external environment such as ADSL or VDSL service through a part of the bundled medium. Especially, in case of instantaneous deterioration of line quality, it is difficult to provide a stable multimedia service because the possibility of damaging a packet transmitted in a multicast scheme increases rapidly, and this problem becomes worse as the length of a line becomes longer.

FIG. 3 is a conceptual diagram illustrating a problem caused by a packet loss that may occur in a multicast service of a subscriber network to which a G.hn technology is applied. As shown in FIG. 3, one of the domain masters 130b is connected to a terminal 40b, In which multimedia data for IPTV broadcasting is transmitted in a multicast manner.

If another domain master changes from an off state to an on state in a process of transmitting multimedia data in a multicast manner (i.e., a UDP packet), a specific crosstalk may occur, and as a result, Some may be lost. If the lost packet corresponds to a part of the compressed multimedia data, some of the screen may be damaged. In general, the entire screen may be damaged until the next key frame reception due to the key frame damage.

Full-HD service requiring 8 ~ 12Mbps bandwidth is generally provided. 4K HD video service (28 ~ 35Mbps bandwidth) providing resolution corresponding to 4 HD screens is being tested, and next generation standard 8K Since support for HD video service (100 ~ 120Mbps bandwidth) is being considered, the quality standards of users receiving recent high definition (HD) or ultra high definition (UHD) video services are very high and visual image damage is easily identified Therefore, even if some packets are damaged, user complaints against them are very large.

Therefore, even a multicast packet transmitted using UDP requires retransmission of a lost packet. In order to do so, unique identification information that can distinguish each packet is required.

FIG. 4 shows a simple communication frame structure, and shows a simplified structure of an Ethernet frame. As shown in the figure, a destination address, a source address, type information, data, and an error check code (e.g., cyclic redundancy check (CRC)) for such information are configured.

In the case of such a standard communication frame, since there is no field for defining a separate identifier for identifying a packet, the frame structure should be changed in order to include an identifier for identifying the packet. However, if the frame structure is changed, it is necessary to change the configuration to process the frame. Therefore, a new design or mass production is required, and existing commercialized processing configurations are not available, . Particularly, when a new identifier field is added to a frame, the transmission speed is delayed and the performance is lowered.

Therefore, according to the embodiment of the present invention, it is possible to retransmit a lost packet by inserting an identifier capable of distinguishing individual packets without changing an existing packet frame. In particular, by enabling such functions to be performed through software changes, it is possible to maintain the compatibility by using the functions according to the embodiments of the present invention or conforming to the existing standards according to the operation mode, thereby improving the usability and applicability .

FIG. 5 is a block diagram of a system for improving multicast service performance of an FTTdp subscriber network using G.hn technology according to an embodiment of the present invention. The domain master 230 corresponding to a port of a concentrator and the terminal 300 ). ≪ / RTI >

First, the domain master 230 includes a frame generation unit 233 for generating a frame for a packet. The domain master 230 can use the conventional conventional frame generation unit 233 as it is. The CRC calculation unit 232 includes an identifier for identifying a corresponding packet in a CRC to be used when generating a frame including such a packet, and an identifier having a predetermined promised pattern for each generated packet to the CRC calculation unit 232 And an identifier generator 231 for generating an identifier. In addition, a transmission packet queue 234 for sequentially storing the packets generated by the frame generation unit 233 and transmitting the packets in a multicast manner, a backup queue 233 for storing a part of the packets transmitted for retransmission of the lost packets, And a retransmission processing unit 236 for selectively retransmitting the packet corresponding to the identifier requested by the retransmission request from the backup queue 235 and retransmitting the packet.

Here, the identifier generation unit 231 includes a step of changing the identification number according to the promised pattern according to the packet order, and this pattern may be a sequentially increasing or decreasing number of n-bit size, for example. Of course, it may be a pattern obtained according to a specific mathematical expression or a pattern such as a known separable sequence.

As a simplest example, an identifier may be defined as 8-bit information identifying a packet and incremented from 0 to 1 according to the packet order. Basically, an identifier for such a packet classification is preferably a unique code, but it may be an implementation-limited unique code.

This identifier can be designed to have a variable size depending on the transmission / reception queue and the transmission rate. Considering that the number of packets buffered in the transmission / reception queue is 200 or less, even if the range of 0 to 255 is repeated, It can have uniqueness. Of course, the size of the identifier may be increased or decreased as needed.

In addition, if the size of the transmission / reception queue excessively increases, the service quality may be deteriorated due to the delay. Therefore, the size of the queue increases when there is a large number of retransmission requests according to the retransmission request status, It is possible to enable delay-optimized transmission by adjusting the queue size.

The CRC calculation unit 232 calculates the CRC of a frame to be transmitted from the domain master 230 (a packet to be transmitted in a multicast manner) (for example, when generating a CRC for the frame) An identifier is added so that an error value corresponding to the identification number is calculated in the process of verifying the error check code. For example, if identification number 1 is inserted as an identifier, a CRC value is generated such that the error value becomes 1 in the CRC verification process.

The terminal 300 includes a reception packet queue 310 for storing received multicast packets, a CRC verification unit 320 for verifying a CRC for a frame including a packet, A retransmission request unit 350 for confirming an identifier corresponding to the lost packet and requesting the domain master 230 to retransmit the identifier to the domain master 230 and an identifier management unit 330 for identifying the identifier of the received packet And a reordering unit 340 for reordering the packets of the received packet queue based on the identifiers upon confirming that the packets are received through the retransmission request based on the reference.

When the CRC verification unit 320 verifies the CRC of the received packet by inserting the number corresponding to the identifier in the domain master 230, the CRC verification unit 320 calculates a value corresponding to the identifier. If the error is calculated, it is not determined that the error is a reception error but the received error is verified by checking whether the pattern of the calculated error is a promised pattern, and at the same time, an identifier of the packet is obtained. For example, if the error calculated for the previous packet is 1 and the promised pattern is a value that increases by 1, it is determined that reception is normal and that the identifier is 2 if the calculated error is 2. If the error is not a promised pattern, it can be determined as a reception error (although, of course, the packet received by the retransmission request may be different from the promised sequential pattern, and this is also handled more).

The identifier management unit 330 manages the identifiers verified by the CRC verification unit 320 in association with the packets received in the reception packet queue 310. When the CRC verification unit 320 receives a packet that is not the promised pattern It is determined that the packet is a reception error, and an identifier corresponding to the packet corresponding to the reception error is generated according to the promised rule, and the generated identifier is provided to the retransmission request unit 350. For example, if the promised pattern is incremented by 1 and the identifier determined to have been normally received is 2, and the next received packet is lost, the identifier management unit 330 stores the packet to be received this time, It is determined that the identifier of the packet is 3 and the identifier 3 is provided to the retransmission request unit 350 to request the domain master 230 to retransmit the packet corresponding to the identifier 3. [

The operation according to the embodiment of the present invention will be described in more detail with reference to FIGS. 6 to 9. FIG.

6, the CRC is calculated using the information of the header and the data portion of the frame, and added to the end of the frame to generate the frame data so that the reception error can be verified .

The CRC calculation is one of several known error checking codes.

When there is n bits of information given, it is shifted up by k bits and divided by the key value of the promised k bits, leaving the remainder of the r bits. On the transmitting side, the original information bit is added to the k bit position and the rest of the r bit is added to generate n + r bits of data. The receiving side divides the received n + r bits of data by the key value and verifies whether the remainder is equal to 0 and verifies the error. If an error occurs, the receiver requests retransmission of the corresponding data.

Of course, the error checking code of the present invention is not limited to the CRC, but may be various other redundant checking codes (e.g., checksum, Longitudinal Redundancy Check (LRC), etc.).

7 shows the process of inserting the identifier generated by the identifier generator 231 into the CRC by the CRC calculator 232. When calculating the CRC using the information of the header and the data portion of the packet frame to be transmitted, The CRC calculation unit 232 generates an identifier generated in accordance with the promised pattern with an error in verification and inserts it into the end of the corresponding frame.

For example, when the identifier generator 231 generates an identifier such that the identifier generator 231 has a value that increases by one every eight bits in units of packets, the identifier may be repeatedly generated from 0x01 to 0xff continuously. The CRC calculation unit 232 inserts the identifiers generated by the identifier generation unit 231 one by one for each packet to be transmitted, and generates a CRC for intentionally generating a corresponding error. Of course, more bits can be used or fewer bits can be used for identifier generation, and promised patterns can be applied to various patterns other than simple increase / decrease.

FIG. 8 shows a concept of applying sequential identifiers to a plurality of sequential frames. The CRC 1 is inserted after the identifier 1 is inserted in the first frame, and the CRC 1 is added. In the second frame, An identifier 2 is inserted to calculate the CRC2 for which the error is intended, and then the CRC2 is appended. In the third frame, the identifier 3 changed in the pattern promised in the identifier 2 is inserted to calculate the CRC3 for which the error is intended.

Since the size of the identifier may be limited, it may be a smaller value again after a predetermined maximum value. For example, if the value is an 8-bit value that increases by 1, the identifier after 0xff may be 0x00, and it may reflect this when checking the identifier pattern.

9 shows a concept of CRC verification in a receiver that receives a frame having an error-intended CRC in the above-described manner. As shown in FIG. 9, the CRC verification unit 320 generates a CRC And the intended error corresponding to the identifier when it is normally received is calculated.

Meanwhile, IEEE 802.1Q is a network standard supporting a virtual LAN (VLAN) in a single Ethernet network. In this standard, contents of a VLAN tag addition system for an Ethernet frame are defined. That is, one or a plurality of VLAN tags can be added to the frame header (QinQ), and the tag information can be set by the user. Therefore, it is possible to add necessary VLAN tags to transmit necessary additional information. Although it is possible to add such a VLAN tag to a transmission frame and designate a packet identifier through the corresponding tag, in the case of the identifier transmission by the additional tag, the network speed degradation due to an increase in the frame capacity may occur. Therefore, it is preferable that the utilization of the VLAN tag is utilized as additional information for verifying an identifier included in the CRC when extreme packet retransmission is required, or for indicating that the packet is a retransmission packet by a retransmission request.

FIG. 10 is a conceptual diagram illustrating an operation method according to an embodiment of the present invention. As shown in FIG. 10, a domain master 230 calculates a CRC including an identifier and provides it to a frame generation unit 233, And sequentially stores the packets in the transmission packet queue 234, and transmits the generated packets to the terminal 300 in a multicast manner in the stored order. In this case, the transmitted packets are stored in the backup queue 235, and the identifiers for the stored packets can be managed separately.

The terminal 300 receives the transmitted multicast packets and stores them in the received packet queue 310. The CRC checking unit 320 checks the CRC of the packet stored therein and identifies the deliberately inserted identifier And verifies compliance with the promised rules. There are two cases when it does not meet the promised rule. One is when an error occurs in the received packet, and the other is when the packet that requested the retransmission is received. The identifier management unit 300 identifies the identifiers of the packets stored in the received packet queue using the identifiers verified by the CRC verification unit 320 and, in the case of the packets lost due to the errors, And transmits the identifier to the retransmission requesting unit 350. [0064] If the received packet does not match the promised pattern but matches the identifier of the packet retransmitted by the retransmission request, the identifier management unit 330 transmits the retransmitted packets including the retransmitted packet through the reordering unit 340 as an identifier (In the case of such a retransmission packet identifier, it may be defined that one of the promised patterns is satisfied if the corresponding identifier is confirmed within a predetermined period after the retransmission request is made according to the setting).

The retransmission request unit 350 requests the domain master 230 to retransmit a packet corresponding to the identifier (identifier '2' in the illustrated example) transmitted through the identifier management unit 330, A protocol can be defined and used, or it can be requested via a previously defined management channel.

When the retransmission processing unit 236 of the domain master 230 receives a request for retransmission of a packet having a specific identifier from the terminal 300, a packet having the same identifier among the packets stored in the backup queue 235 is transmitted to the transmission packet queue 234. [ As shown in FIG.

In this case, the CRC verification unit 320 and the identifier management unit 330 of the UE may transmit the packet through the management channel or the other kind of channel, Lt; RTI ID = 0.0 > retransmission < / RTI > Of course, even if a retransmission packet is received through such a separate channel, the reordering process of the received packet queue based on the identifier can be performed.

Meanwhile, the size of the transmission / reception queue (and the size of the backup queue) can be adaptively adjusted according to the frequency of the retransmission request, thereby enabling the delay optimization transmission.

11 is a flowchart illustrating a multicast service process of an FTTdp subscriber network using G.hn technology according to an embodiment of the present invention. As shown in the figure, the upper part of the area divided by the dotted line is a step performed in the domain master and the lower part is a step performed in the terminal.

First, when generating an error check code for a packet frame to be transmitted from the domain master in a multicast manner, an error check code for adding an identification number is generated so that an error value corresponding to the identification number is calculated during the error check code verification process. And generates a packet frame in which the error check code is inserted.

The generated multicast transmission packet is stored in the transmission packet queue and transmitted to the mobile station, and the transmitted packets are temporarily stored in a backup queue of a predetermined size.

The terminal calculates the identification number corresponding to the error by verifying the error check code of the received packet while storing the packet received in the multicast method in the received packet queue.

If the calculated identification number matches the promised identifier pattern (in the case of a retransmission packet, it is processed in the order shown in the case of processing as a part of the identifier pattern, otherwise it can be checked first whether the packet is a retransmission packet) If the packet is a retransmission packet, the packet stored in the reception queue is rearranged according to the identification number and stored again.

If it does not match the promised identifier pattern, the packet is discarded due to a packet reception error, and a request is made to the domain master for retransmission of the packet for the identification number in that order.

If there is a retransmission request, the domain master selects a packet corresponding to the requested identification number from the backup queue and transmits it to the terminal through the transmission packet queue.

Although not shown, a process of adaptively adjusting the size of the transmission / reception queue (and the size of the backup queue) according to the frequency of the retransmission request may be included.

The G.hn based FTTdp subscriber network, where various line environment changes occur through this process, will enable reliable multicast services, improve the quality of providing high quality multimedia services, and, above all, It is possible to extend the service range of the subscriber's network.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or essential characteristics thereof. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

200: aggregation equipment (GAM) 230: domain master
231: identifier generation unit 232: CRC calculation unit
233: frame generation unit 234: transmission packet queue
235: backup queue 236: retransmission processing section
300: Terminal 310: Received Packet Queue
320: CRC verification unit 330:
340: Reorder section 350:

Claims (9)

(Fiber To The Distribution (FTT)) with G.hn technology, which is composed of a CPE (Customer Premises Equipment) and a central office (CO) having a plurality of ports connected to each terminal through a domestic line bundled with each terminal point) multicast service performance improvement method of a subscriber network,
An error check code generation step of adding an identification number so that an error value corresponding to an identification number is calculated in an error check code verification process when generating an error check code for a packet to be transmitted in a multicast manner by a concentrator;
A transmitting step of a collecting device transmitting a packet including an identification number to a terminal through a transmission packet queue in a multicast manner;
A receiving step of verifying an error check code of a received packet while storing a packet received by the terminal in a received packet queue in a multicast manner and calculating an identification number corresponding to the error;
A retransmission request step of requesting retransmission of a packet having an identification number corresponding to the received packet to a concentrator when it is determined that the received packet is damaged when the identification number calculated in the reception step is out of a predetermined pattern;
And a retransmission step of retransmitting the packet corresponding to the identification number to the terminal when the aggregation equipment receives a packet retransmission request from the terminal.
2. The method of claim 1, further comprising reordering the packets of the received packet queue based on the identification number of the received packets when the terminal receives the retransmitted packet from the concentrator, A Method for Improving Performance of Multicast Service of Net.
The method of claim 1, wherein the error checking code generation step, the transmission step, and the retransmission step are performed for each port of the aggregation equipment.
The method of claim 1, wherein the transmitting step further comprises temporarily storing packets stored in a transmission packet queue in a backup queue having a predetermined size,
Wherein the retransmitting step further comprises retransmitting the retransmission request packet from the backup queue based on the identification number and retransmitting the retransmitted packet.
The method of claim 1, wherein the step of generating the error confirmation code comprises the step of changing the identification number according to the promised pattern according to the packet order, wherein the identification number is a unique value for each packet received in the received packet queue To improve performance of multicast service of FTTdp subscriber network with G.hn technology.
[6] The method of claim 5, wherein the predetermined pattern is a sequence of n-bit sequential increases or decreases.
The method of claim 1, wherein the error check code is a cyclic redundancy check (CRC).
The method according to claim 1, wherein the size of the transmission packet queue or the reception packet queue is adaptively adjusted according to the capacity of the terminal or the terminal according to the frequency of the packet retransmission request, the multicast service performance improvement of the FTTdp subscriber network to which the G.hn technology is applied Way.
The method of claim 1, wherein the aggregation equipment adds a VLAN tag to a frame for packet transmission after the error check code generation step, and transmits information for verifying an identification number included in the error check code or retransmission Further comprising the step of inserting information for identifying the packet according to the request. The method for improving the multicast service performance of the FTTdp subscriber network to which the G.hn technology is applied.

Images