KR20120068536A - Apparatus and method for operating cable modem termination system in cable network communication system - Google Patents

Abstract

PURPOSE: A device and a method for operating a cable modem termination system(CMTS) in a cable network communication system are provided to implement a cutting operation with respect to a corresponding service defined in one CMTS if an error is generated in the core of the CMTS. CONSTITUTION: A contents server system(101) provides an electronic program guide and video on demand service contents. A DOCSIS timing interface service(103) secures the same period of times for the time synchronization of CMTS cores(104 to 107) and the time synchronization of the CMTS cores and edge-quadrature amplitude modulation(EQAM). An operating system support server operates and manages networks. The EQAM modulates media access controlling data into QAM.

Description

Apparatus and method for operating CMTs in cable network communication system {APPARATUS AND METHOD FOR OPERATING CABLE MODEM TERMINATION SYSTEM IN CABLE NETWORK COMMUNICATION SYSTEM}

The present invention relates to a cable network communication system. More particularly, the present invention provides a plurality of cable mode termination systems (CMTSs) at a head end to provide rapid failure recovery and maximum service continuity. The present invention relates to a network operating system, an apparatus, and a method in charge of CMTSs.

In a cable network, a communication system generally has one cable modem termination system (CMTS) at a headend and communicates with cable modems (CMs) in the homes of several subscribers. Under this structure, if the CMTS fails, the communication service of all subscribers is disconnected. In addition, since the CMTS must proceed with the initialization process with all CMs again at the point of failure recovery, it takes quite a long time for all subscribers to receive normal service again.

There is a way to put a backup CMTS for quick recovery from network failures. In other words, if one CMTS fails, the system switches to the backup CMTS. Even in this case, since the initialization process needs to be performed for all CMs, it takes a lot of time for normal service to be performed. In addition, service continuity cannot be maintained because all connected services are disconnected before failure.

The technical problem of the present invention is to provide a network management system, apparatus and method for each CMTS for each service with a number of CMTS in the head end to ensure rapid failure recovery and maximum service continuity in the cable network.

Another technical problem of the present invention is to provide a system, an apparatus, and a method in which multiple CMTSs share an up and down channel for communicating with each CM.

According to an aspect of the present invention, there is provided a system for operating a cable modem termination system (CMTS) in a cable network communication system. The system performs a function of a medium access control (MAC) layer, transmits downlink MAC data to edge-quadature amplitude modulation (EQAM) based on DEPI (DOCSIS External PHY Interface), and modularizes each function. And a plurality of CMTS for providing different services, EQAM for QAM modulating the downlink MAC data and transmitting them to a physical channel, and a first time synchronization between the plurality of CMTS and a second time synchronization between the plurality of CMTS and the EQAM. It includes a DTI (DOCSIS Timing Interface) server that controls it.

The plurality of CMTS and the EQAM may operate in a data transmission mode of a PSP mode.

In the cable network according to the present invention, even if one CMTS core fails, only the service limited to the CMTS is disconnected to the subscriber, and other services can be maintained. In addition, since the initialization of all CMs due to a failure is not necessary, rapid failure recovery is possible. In addition, the CMTS that supports only a specific service can be used, compared to the expensive CMTS that provides all services, thereby reducing the unit price of the CMTS.

1 is a block diagram showing the structure of a cable network system according to an embodiment of the present invention.
2 is a conceptual diagram illustrating a method in which a plurality of CMTS cores share a downlink channel according to an embodiment of the present invention.
3 is a conceptual diagram illustrating a method in which a plurality of CMTS cores share an uplink channel according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise. Also, the term "part" or the like, as described in the specification, means a unit for processing at least one function or operation, and may be implemented by hardware, software, or a combination of hardware and software.

1 is a block diagram showing the structure of a cable network system according to an embodiment of the present invention.

Referring to FIG. 1, the cable network system 100 includes a content server system 101, an external network 102, a DOCSIS Timing Interface (DTI) server 103, a plurality of CMTS cores 104, 105, and 106. 107), Operating System Support (OSS) Server 108, Edge-Quadrature Amplitude Modulation (EQAM), Uplink Stream (US) Splitter (110), Hybrid Fiber-Coaxial (HFC) Network (HFC) 111) and a cable modem (112).

The content server system 101 provides an electronic program guide (EPG), video on demand (VOD) service content, and the like.

The external network 102 may be a backbone network or a core network of a cable network as a high speed network.

The DTI server 103 uses the same time for temporal synchronization between the plurality of CMTS cores 104, 105, 106, and 107 and the temporal synchronization between the CMTS cores 104, 105, 106, 107 and the EQAM 109. To provide.

The OSS server 108 operates and manages the network. For example, OSS server 108 manages network resources such that a plurality of CMTS cores 104, 105, 106, 107 share limited channel capacity.

The EQAM 109 modulates Medium Access Control (MAC) data received from the plurality of CMTS cores 104, 105, 106, and 107 into QAM and transmits the modulated data to a cable network, which is a physical channel.

The upstream branching unit 110 is a kind of radio frequency (RF) signal branching unit, and simply performs the function of equally distributing one RF signal to all CMTS cores 104, 105, 106, and 107.

The plurality of CMTS cores 104, 105, 106, and 107 may be Modular-CMTS (M-CMTS) cores, which are modularized TSTS in the DOCSIS standard. According to this, a plurality of CMTS cores 104, 105, 106, and 107 are responsible for the MAC layer function, and the EQAM 109 is responsible for the physical layer function. In this way, if multiple CMTS cores are used and each CMTS core supports only a specific application or a specific service and communicates with the CMs, the cable modems can support the application even if the CMTS core supporting one application fails. You will not only receive services for the service, but you will be able to continue with the rest of the service. In addition, failure recovery can be done very quickly because no initialization is required.

Each CMTS core 104, 105, 106, 107 is configured to support a particular service. For example, the CMTS core 104 supports Voice over Internet Protocol (VoIP) services, the CMTS core 105 supports DOCSIS Set-top Gateway (DGS) services, and the CMTS core 106 supports VOD services. And the remaining CMTS cores 107 may support Internet services. In this structure, if one CMTS core fails, only the corresponding service is disconnected, and communication with the cable modem 112 is still valid, and other services can be normally provided.

In FIG. 1, only four CMTS cores 104, 105, 106, and 107 are illustrated, but this is only an example and the inventive concept is not limited to the number of CMTS cores shown in FIG. 1.

Each CMTS core 104, 105, 106, 107 transmits downlink data to the EQAM 109 based on an interface defined in the DEPI (DOCSIS External PHY Interface) standard. According to the DEPI specification, data can be transmitted from one CMAM core to one EQAM.

When an uplink stream is input to each CMTS core 104, 105, 106, and 107 through the upstream brancher 110, each CMTS core 104, 105, 106, and 107 filters only the stream corresponding to it. filtering).

On the other hand, in order for several CMTS cores to communicate with cable modems, there must be a solution related to uplink / downlink channel sharing. In addition, since channel capacity is limited, a management method is required in which each CMTS does not exceed a certain amount of network load.

2 is a conceptual diagram illustrating a method in which a plurality of CMTS cores share a downlink channel according to an embodiment of the present invention.

Referring to FIG. 2, four CMTS cores share four downlink channels in a channel combining environment of DOCSIS 3.0. CMTS 1, CMTS 2, CMTS 3 and CMTS 4 provide VoIP service, DSG service, VOD service and Internet service, respectively.

Basically, EQAM can be configured so that multiple CMTS cores share a specific downlink channel or each can use a different channel. The DOCSIS 3.0 specification introduces a downlink channel combining function so that one cable modem can receive multiple downlink channels. Therefore, it is possible to configure the form in which a specific service is transmitted for each channel, and can also be transmitted by sharing all channels. For example, as shown in FIG. 2, CMTS 4 and CMTS 3 use downlink channel 1 and channel 2, respectively, and CMTS 1 and CMTS 2 share downlink channel 3.

The DEPI specification, which defines the interface between the CMTS core and EQAM, defines PSP (Packet Streaming Protocol) and MPT (MPT-2) modes as data transmission modes. PSP mode is preferred over MPT mode.

The reason for this is as follows. In general, in the MPT mode, MAC frames are converted into MPEG-2 TS packets, which are input formats defined in the physical layer, in order to transmit the MAC frames. That is, a variable length MAC frame is converted into a fixed length TS (transport stream) packet and transmitted at a constant rate. That is, when the MPT mode is used, the TS format that has already been converted must be transmitted. In this case, if the TS packets generated by each CMTS core are to receive EQAM and share each channel, the reception error may occur at the receiving side because the value of the Continuous Count field of the TS packet header is not continuous. . Therefore, the MPT mode is not suitable for sharing the downlink channel.

On the other hand, in the PSP mode, the MAC frame is transmitted from the CMTS core to the EQAM as it is. In the PSP mode, since the EQAM receives the MAC frame and converts it into a TS packet, an error such as the MPT mode does not occur. As shown in FIG. 2, when a MAC frame transmitted from each CMTS core is input to the transmission queue of EQAM, it is converted into an MPEG-2 TS packet. The converted TS packets are stored in the transmission queue for each channel so as to be transmitted for each channel. In the order of storing, even if one MAC frame is divided into several TS packets as in the example of FIG. 2, one MAC frame is transmitted in one channel so that the MAC frame can be reassembled at the receiving side. However, when the DSID (Downstream Service ID) is applied differently for each service, the receiver may rearrange the output order after MAC frame reassembly.

3 is a conceptual diagram illustrating a method in which a plurality of CMTS cores share an uplink channel according to an embodiment of the present invention.

Referring to FIG. 3, an example in which four CMTS cores share four uplink channels to allocate bands in a channel combining environment of DOCSIS 3.0 is provided. It is assumed that CMTS 1, CMTS 2, CMTS 3, and CMTS 4 provide different services.

In uplink, several physical channels may be combined. Unlike in the case where one CMTS core exists, the bandwidth allocation for cable modems is relatively complicated in the multiple CMTS core system because scheduling is performed for uplink channels of a plurality of CMTS cores. For example, as shown in FIG. 3, each CMTS core is divided into bands in time. The downlink channel is a method in which data is broadcast to all cable modems, but the uplink channel is logically time-divided into channels to transmit data to all cable modems.

In DCOSIS, uplink band allocation is performed through a MAP message. The MAP message is periodically transmitted to all cable modems through the downlink channel for transmission time and length information for the allocated band. This allows the cable modem to transmit data in the corresponding time period.

In DOCSIS 3.0 specification, data is transmitted based on logical channel, not physical channel. In FIG. 3, each CMTS core divides an uplink band in time. In the CMTS core, the MAP message must transmit the MAP for all physical channels used by the cable modem without any time gap. That is, in the example of FIG. 3, each CMTS core must generate a MAP message even for a section not used by itself, and in this case, all bands in the MAP message are defined as Null Interval Elements (IEs). From the cable modem's point of view, four MAP messages exist for each physical channel for the same time interval, and bands are allocated from valid MAP messages in the corresponding interval.

In this case, there are substantially four uplink physical channels, but logically there are 16 channels. In order to share such an uplink channel, a channel usage interval for channel sharing between each CMTS cores must be promised in advance, and the OSS server grasps the channel operation status of each CMTS core and manages it dynamically.

Meanwhile, the apparatus and method according to the present invention described above may be embodied as computer readable codes / instructions / programs. For example, it may be implemented in a general-purpose digital computer for operating the code / instructions / program using a computer-readable recording medium. The computer-readable recording medium may include a magnetic storage medium (eg, ROM, floppy disk, hard disk, magnetic tape, etc.), an optical reading medium (eg, CD-ROM, DVD, etc.) and a carrier wave (eg Storage media, such as through the Internet). In addition, embodiments of the present invention may be implemented as a medium (s) containing computer readable code, such that a plurality of computer systems connected through a network may be distributed and processed. Functional programs, codes and code segments for realizing the present invention can be easily inferred by programmers in the art to which the present invention belongs.

Although the present invention has been described with reference to the embodiments shown in the drawings for clarity, this is merely exemplary, and various modifications and equivalent other embodiments are possible to those skilled in the art. Will understand. Therefore, the true technical protection scope of the present invention will be defined by the appended claims.

Claims (1)

In the cable system communication system CMTS (Cable Modem Termination System) operating system,
It performs the function of Medium Access Control (MAC) layer and transmits downlink MAC data to Edge-Quadrature Amplitude Modulation (EQAM) based on DEPI (DOCSIS External PHY Interface). A plurality of CMTSs for providing a service;
EQAM for QAM modulation on the downlink MAC data and transmitting the same on the physical channel; And
A DOCSIS Timing Interface (DTI) server controlling a first time synchronization between the plurality of CMTSs and a second time synchronization between the plurality of CMTSs and the EQAM,
And the plurality of CMTS and the EQAM operate in a data transmission mode of a PSP (Packet Streaming Protocol) mode.

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