WO2008100003A1

WO2008100003A1 - Device and method for buffering data in the hybrid-fiber coaxial

Info

Publication number: WO2008100003A1
Application number: PCT/KR2007/005576
Authority: WO
Inventors: Hyung Suk Choi; Dong Young Park; Hyung Jun Lim
Original assignee: Ls Cable Ltd.
Priority date: 2007-02-16
Filing date: 2007-11-06
Publication date: 2008-08-21
Also published as: KR100826224B1

Abstract

Disclosed are a device for buffering data in a hybrid-fiber coax and a method for the same, which reduce a load of a service providing side in the hybrid-fiber coax, and improve a data transmission rate and a data throughput from the service providing side to a subscriber side.

Description

DEVICE AND METHOD FOR BUFFERING DATAIN THE HYBRID-FIBER

COAXIAL

Technical Field The present invention relates to a device for buffering data in a hybrid-fiber coaxial system and a method for the same, and more particularly, to a device for buffering data in a hybrid-fiber coax and a method for the same, which reduce a load of a service providing side in the hybrid-fiber coax, and improve a data transmission rate and a data throughput from the service providing side to a subscriber side.

Background Art

A hybrid-fiber coax includes an optical fiber (or optical cable) and a coaxial cable, and can transmit a data signal, for example, for the Internet, cable television, crime prevention, disaster prevention, remote inspection, and automatic control to a broadcasting station and an optical network unit via the optical fiber, and from the optical network unit to a subscriber via the coaxial cable.

FIG. 1 illustrates a configuration of an entire network in a conventional hybrid- fiber coax.

The hybrid-fiber coax as shown in FKJ. 1 includes a cable television (CATV) system, an optical transmitter (OTX), a video on demand (VOD), an Internet network, a voice over Internet protocol gate/keeper (VoIP G/K), which are installed in a service providing side 110, and a plurality of terminals such as a television, a personal computer (PC), a telephone, and an air conditioner, which are installed in a subscriber side 150. Also, an optical fiber 120, an optical network unit (ONU) 130, and a coaxial cable 140 may be installed between the service providing side 110 and the subscriber side 150.

The ONU 130 in the hybrid-fiber coax may be constructed by replacing an existing modem (CMTS: Cable Modem Termination System) equipment of the hybrid- fiber coax and an upstream amplifier of an existing ONU, and acts as a server managing terminals (clients) installed in the subscriber side 150.

In the hybrid-fiber coax, the subscriber side is managed as cell units by the ONU 130, however, all processes for data transmission to the subscriber side 150 are performed in the service providing side 110, and thus data transmission capability of the service providing side 110 is overloaded and taxed.

Also, since data, which is received in a relatively higher speed from the service providing side 110 of the hybrid-fiber coax via the optical fiber 120, is transmitted in a relatively lower speed to the subscriber side 150 via the coaxial cable 140, the difference in the data transmission rate occurring due to a difference between the transmission mediums causes problems such as transmission delay of the entire network, a bottleneck state, and the like.

Also, User Created Contents (UCC) is a newly-coined word which refers to on- line contents that are created by netizens. Currently, these contents including images, digital videos, photographs taken by mobile devices, moving pictures, and the like have gained tremendous popularity on the Internet. In this regard, as a pay audio on demand (AOD) and a pay VOD increase, there arises a need for a network configuration where a large amount of contents, particularly, VOD streaming data, are transmitted to a user in real time without being delayed.

Accordingly, there is a need for development of technologies which may solve problems such as a load in the service providing side occurring due to the above- described overload of the transmission capability in the hybrid-fiber coax, and the transmission delay occurring due to the difference between respective transmission mediums of the optical cable and the coaxial cable, so that the transmission of the large amount of streaming data can be readily performed.

Disclosure of Invention Technical Goals An aspect of the present invention provides a device for buffering data in a hybrid-fiber coax and a method for the same in which data transmission to a subscriber side is performed via a buffer memory installed on a transmission line of the hybrid- fiber coax, thereby reducing a load of a service providing terminal.

Another aspect of the present invention provides a device for buffering data in a hybrid-fiber coax and a method for the same in which difference in transmission speed of an optical cable and a coaxial cable is adjusted, thereby improving a speed of an entire network and transmission efficiency. Technical solutions

According to an aspect of the present invention, there is provided a device for buffering data in a hybrid-fiber coax, which includes a buffer memory for receiving, from a service providing side of the hybrid-fiber coax, data via an optical cable, and storing the received data; and a buffer control unit for controlling transmission of the received data. In this instance, the buffer memory transmits the stored data to a subscriber side via a coaxial cable depending on control of the buffer control unit.

According to another aspect of the present invention, there is provided a method for buffering data in a hybrid-fiber coax, which includes receiving, from a subscriber side, a data transmission request; retrieving the requested data from a buffer memory; when the requested data does not exist in the buffer memory, requesting a service providing side of the hybrid-fiber coax for the requested data, receiving the requested data from the service providing side via an optical cable, and storing the received data in the buffer memory; and transmitting the data stored in the buffer memory to the subscriber side via a coaxial cable. In this instance, the transmitting transmits the stored data to the subscriber side while receiving data from the service providing terminal.

Brief Description of Drawings

FIG. 1 illustrates a configuration of an entire network in a conventional hybrid- fiber coax;

FIG. 2 illustrates a configuration of a device for buffering data in a hybrid-fiber coax according to an exemplary embodiment of the present invention; FIG. 3 illustrates a configuration of a hybrid-fiber coax where a subscriber side is managed as cell units by an optical network unit (ONU) according to an exemplary embodiment of the present invention;

FIG. 4 is a flowchart illustrating a method for buffering data in a hybrid-fiber coax according to an exemplary embodiment of the present invention; and FIG. 5 illustrates a configuration of a network for bidirectionally buffering data using a device for buffering data in a hybrid-fiber coax according to another exemplary embodiment of the present invention. Best Mode for Carrying Out the Invention

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.

FIG. 2 illustrates a configuration of a device for buffering data in a hybrid- fiber coax according to an exemplary embodiment of the present invention.

A service providing side 210 according to the present exemplary embodiment of the invention functions to provide services in the hybrid-fiber coax, and may be interpreted as a general concept including at least one of cable television (CATV) services, video on demand (VOD) services, Internet services, voice over Internet protocol (VoIP) services, according to service types.

Also, the service providing side 210 according to the present exemplary embodiment of the invention may be a station acting as a headend, which is connected with another communication network to receive a terrestrial television broadcasting program or a satellite television broadcasting program and send the received program to a coaxial cable or an optical cable, or may be a system operator (SO) or a broadcasting server which sends their own programs created by CATV broadcasters or programs provided by program providers to a cable.

The device for buffering data in the hybrid-fiber coax according to the present exemplary embodiment of the invention includes a buffer memory 230 and a buffer control unit 240.

In general, the buffer memory denotes a storage place where data is temporarily stored in order to overcome a problem that a processing speed of peripheral devices is relatively slower than that of a central processing unit (CPU), and also denotes a device facilitating to independently operate two different systems. The buffer memory 230 of the present exemplary embodiment of the invention is a storage place where data is temporarily stored in order to adjust a difference in data transmission rate between a relatively lower-speed transmission medium of an optical cable 220 and a relatively lower-speed transmission medium of a coaxial cable 250 in the hybrid-fiber coax, and may be installed within an optical network unit (ONU) intermediating between the optical cable 220 and the coaxial cable 250. The buffer memory 230 temporarily stores data received in a relatively higher speed from the service providing side 210 of the hybrid-fiber coax via the optical cable 220, and transmits the stored data to the subscriber side 260 via the coaxial cable 250 according to control of the buffer control unit 240, thereby preventing a bottleneck state of data transmission from occurring, and improving a speed of an entire network.

In this instance, the buffer memory 230 may transmit, to the subscriber side 260, data having been stored so far in the buffer memory 230 according to the control of the buffer control unit 240 while receiving data from the service providing side 210 of the hybrid-fiber coax. As a result, the buffer memory 230 can ontinuously transmit data to the subscriber side 260 without waiting for all data to be transmitted to the buffer memory 230.

The buffer control unit 240 controls transmission of data received in the buffer memory 230 to the subscriber side 260. For example, when the buffer control unit 240 receives a data transmission request from the subscriber side 260, the buffer control unit 240 determines whether data corresponding to the received data transmission request is stored in the buffer memory 230. When corresponding data is stored in the buffer memory 230 according to the determination result, data corresponding to the data transmission request is transmitted to the subscriber side 260, and when the corresponding data is not stored in the buffer memory 230 according to the determination result, the service providing side 210 is requested for the data corresponding to the data transmission request.

A device 270 for buffering data in the hybrid-fiber coax according to the present exemplary embodiment of the invention may be located on a transmission line from the service providing side 210 to the subscriber side 260, and installed in the ONU functioning to manage the subscriber side 260.

Data transmitted from the service providing side 210 to the subscriber side 260 of the hybrid-fiber coax of the present exemplary embodiment of the invention may be streaming data transmitted in real time, such as audio on demand (AOD), VOD, animation, and the like, which are reproduced in the Internet, or data frequently updated.

In general, the streaming data denotes data reproduced in real time without being stored in a terminal of a subscriber. Since the streaming data is transmitted at an uneven speed depending on states of the Internet network, by buffering data, the transmission of the streaming data requiring to maximally prevent suspended or delayed streaming data is possible. According to the present exemplary embodiment of the invention, by buffering the streaming data transmitted from the service providing side 210 through the device 270 for buffering data in the hybrid-fiber coax, the streaming data is continuously transmitted to the subscriber side 260.

FIG. 3 illustrates a configuration of a hybrid-fiber coax where a subscriber side is managed as cell units by an optical network unit (ONU) according to an exemplary embodiment of the present invention. The hybrid-fiber coax is connected with an ONU 330 from a service providing side 310 via an optical cable 320, and further connected a subscriber side 350 via a coaxial cable 340. The subscriber side 350 of the hybrid-fiber coax according to the present exemplary embodiment of the invention may be managed by the ONU 330 including the device 270 for buffering data of FIG. 2, as cell units, such as Cell #1 360, Cell #2 370, ^{• • •}, and Cell #n 380. Accordingly, a repeated data processing (for example, retransmission of data) of the service providing side 310 may be performed in Cell #11 360 through the device for buffering data, thereby reducing a load in the service providing side 310.

FIG. 4 is a flowchart illustrating a method for buffering data in a hybrid-fiber coax according to an exemplary embodiment of the present invention.

First, in operation S410, the device 270 for buffering data determines whether a data transmission request is received from the subscriber side 260 of the hybrid-fiber coax.

The device 270 for buffering data includes the buffer memory 230 where data is temporarily stored in order to adjust the difference in the data transmission rate of the high-speed transmission medium of the optical cable 220 and the low-speed transmission medium of the coaxial cable 250 in the hybrid-fiber coax, and the buffer control unit 240 for controlling transmission of data received in the buffer memory 230 to the subscriber side 260. The device 270 for buffering data may be installed and used within the ONU intermediating between the optical cable 220 and the coaxial cable 250.

When the data transmission request is not received according to the determination result of operation S410, a stand-by state for the data transmission request reception is maintained, and when the data transmission request is received according to the determination result, the requested data is retrieved in the buffer memory 230 in operation S420. In operations S430 and S440, when the data does not exist in the buffer memory 230 according to the retrieval result of operation S420, the service providing side 210 of the hybrid-fiber coax is requested for the data transmission, the requested data is received from the service providing side 210 via the optical cable 220, and the received data is stored in the buffer memory 230. The data transmitted from the service providing side 310 to the subscriber side

260 of the hybrid-fiber coax may be streaming data transmitted in real time such as AOD, VOD, animation, and the like which are reproduced in the Internet, or data frequently updated.

When the data exists in the buffer memory 230 according to the retrieval result of operation S420, operation S450 is performed.

In operation S450, data stored in the buffer memory 230 is transmitted to the subscriber side 260 via the coaxial cable 250.

For example, in operations S440 and S450, the buffer memory 230 of the buffering device 270 transmits data having been stored so far in the buffer memory 230 to the subscriber side 260 depending on control of the buffer control unit 240 while receiving data from the service providing side 210 of the hybrid-fiber coax, thereby enabling receiving/transmitting of data in parallel.

As described above, the device 270 for buffering data according to the present exemplary embodiment of the invention may retrieve the requested data from the buffer memory of the buffering device 270 depending on the data transmission request received from the subscriber side of the hybrid-fiber coax and transmit the retrieved data, or request the service providing side for the requested data, thereby enabling data transmission to the subscriber side in one-way direction.

According to another exemplary embodiment of the invention, by responding a data transmission request from another user connecting with a head-end (or service providing side) of the hybrid-fiber coax, when a service request which occurs from the head-end is received, data bidirectionally requested may be transmitted through the device for buffering data.

The other user may be a user connecting with the head-end through the hybrid- fiber coax of the present exemplary embodiment of the invention or another communication network other than the hybrid-fiber coax. The data requested from the other user may be streaming data transmitted in real time such as AOD, VOD, animations, and the like, which are reproduced in the Internet, or data frequently updated.

FIG. 5 illustrates a configuration of a network for bidirectionally buffering data using a device for buffering data in a hybrid-fiber coax according to another exemplary embodiment of the present invention.

When a head-end 510 connected with a device 520 for buffering data of the present exemplary embodiment of the invention via a hybrid fiber coax (HFC) receives signals for data transmission request from another user 540 connected via a communication network, the requested data is retrieved within the head-end 510. When the requested data does not exist within the head-end 510 connected with the buffering device 520 via the HFC, the head-end 510 requests the buffering device 520 for the requested data. When the requested data exists in a buffer memory of the device 520, data is provided to the other user 540 via the head-end 510. Conversely, when the requested data does not exist in the buffer memory, the request for the requested data to the buffering device 520 is transmitted to the user 530 connecting with the buffering device 520 via the HFC, and data received from the user 530 may be provided to the other user 540 via the head-end 510.

The device for buffering data according to the above-described embodiments of the invention, that enables bidirectional VOD services, receives a data transmission request of a user in a relatively higher speed through an optical network (or optical cable) of the hybrid-fiber coax via the head-end so that a network performance is improved in comparison with a reception scheme of the data transmission via the coaxial cable in a relatively lower speed.

The above-described exemplary embodiments of the present invention may be recorded in computer-readable media including program instructions to implement various operations embodied by a computer. The media may also include, alone or in combination with the program instructions, data files, data structures, and the like. The media and program instructions may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer- readable media include magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD ROM disks and DVD; magneto-optical media such as optical disks; and hardware devices that are specially configured to store and perform program instructions, such as read-only memory (ROM), random access memory (RAM), flash memory, and the like. Examples of program instructions include both machine code, such as produced by a compiler, and files containing higher level code that may be executed by the computer using an interpreter. The described hardware devices may be configured to act as one or more software modules in order to perform the operations of the above-described exemplary embodiments of the present invention.

As described above, according to the present invention, a repeated data process of the service providing side is performed in cell units through the buffer memory installed in a transmission line of the hybrid-fiber coax, thereby reducing a load of the service providing side.

According to the present invention, difference in the data transmission rate of the optical cable and the coaxial cable is adjusted through the buffer memory installed in a transmission line of the hybrid-fiber coax, thereby improving a response speed of the subscriber side, an entire network speed, and transmission efficiency

According to the present invention, bidirectional VOD services are possible, and a data transmission request of a user is received in a relatively higher speed through an optical network (or optical cable) of the hybrid-fiber coax via the head-end (or service providing side), thereby improving a network performance in comparison with a reception scheme of the data transmission via the coaxial cable in a relatively lower speed.

Although a few embodiments of the present invention have been shown and described, the present invention is not limited to the described embodiments. Instead, it would be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A device for buffering data in a hybrid-fiber coax, the device comprising: a buffer memory for receiving, from a service providing side of the hybrid- fiber coax, data via an optical cable, and storing the received data; and a buffer control unit for controlling transmission of the received data, wherein the buffer memory transmits the stored data to a subscriber side via a coaxial cable depending on control of the buffer control unit.

2. The device of claim 1, wherein the device is installed in an optical network unit.

3. The device of claim 1, wherein the data is streaming data or frequently updated data.

4. The device of claim 1, wherein the buffer control unit receives, from the subscriber side, a data transmission request, determines whether data corresponding to the received data transmission request is stored in the buffer memory, and when the data is not stored in the buffer memory according to the determination result, requests the service providing side for the data corresponding to the received data transmission request.

5. The device of claim 1, wherein the buffer memory transmits the stored data to the subscriber side while receiving data from the service providing side of the hybrid- fiber coax.

6. The device of claim 1, wherein the device is connected with a plurality of subscriber sides via the coaxial cable to manage the plurality of subscriber sides as cell units.

7. A method for buffering data in a hybrid-fiber coax, the method comprising: receiving, from a subscriber side, a data transmission request; retrieving the requested data from a buffer memory; when the requested data does not exist in the buffer memory, requesting a service providing side of the hybrid-fiber coax for the requested data, receiving the requested data from the service providing side via an optical cable, and storing the received data in the buffer memory; and transmitting the data stored in the buffer memory to the subscriber side via a coaxial cable, wherein the transmitting transmits the stored data to the subscriber side while receiving data from the service providing terminal.

8. A computer-readable recording medium storing a program for implementing the method of claim 7.