KR100938259B1 - CATV network system and method for providing IPTV service - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

The present invention relates to a CATV network system having an IPTV service providing function and a method thereof.

2. The technical problem to be solved by the invention

The present invention integrates the bandwidth of a broadcast service and a communication service and replaces a broadcast channel with an IPTV service on an IP layer that is transmitted by a user's request, without considering a channel change delay in consideration of the DOCSIS protocol, which is a MAC protocol of a CATV network. The purpose of the present invention is to provide a CATV network system having a function of providing an IPTV service and a method thereof to support a smooth channel change of a user and to efficiently use an uplink band by providing an IPTV service.

3. Summary of Solution to Invention

The present invention relates to a CATV network system having an IIPTV service providing function, which receives all channel data from a broadcast server, integrates the bandwidth of a broadcast service with the bandwidth of a communication service, and provides a DOCSIS protocol extension stack that is a MAC protocol of a CATV network. Provides the channel data requested from the cable modem (CM) without channel change delay based on the hierarchical structure, but when operating in the continuous channel change mode, the adjacent channel ('current channel') of the channel being watched by the user ('current channel') A cable modem termination device for transmitting the first neighbor channel) in advance according to an uplink allocation interval (Grant Interval); And a plurality of cable modems for requesting specific channel data from the cable modem end device and receiving the corresponding channel data.

4. Important uses of the invention

The present invention is used in CATV network system and the like.

IPTV Service, CATV Network, Bandwidth Integration, DOCSIS Protocol, USG Service Class

Description

CATV network system having IPTV service providing function and method therefor {CATV network system and method for providing IPTV service}

1 is a configuration diagram of an embodiment of a CATV network system of a general bidirectional HFC structure;

2 is an exemplary diagram illustrating bandwidth for a CATV network of a general bidirectional HFC structure;

3 is an exemplary diagram for a hierarchical structure of a DOCSIS protocol extension stack according to the present invention;

4 is an exemplary view of a USG service class applied to the present invention;

5 is an example of an rtPS service class applied to the present invention;

6 is a configuration diagram of an embodiment of a CATV network system having an IPTV service providing function according to the present invention;

7 is a diagram illustrating an embodiment of a process for providing an IPTV service in a CATV network system according to the present invention;

8 is an exemplary explanatory diagram showing a relationship between channel delay and GI according to the present invention;

9 is a diagram illustrating an embodiment of a channel change management process under a continuous channel change situation according to the present invention;

FIG. 10 is an exemplary view illustrating performance of channel change delay in a CATV network system having an IPTV service providing function according to the present invention.

* Explanation of symbols for the main parts of the drawings

61: CMTS 62: CM

The present invention relates to a CATV network system having a function of providing an IPTV service and a method thereof, and more particularly, to an IPTV service on an IP layer that integrates a bandwidth of a broadcast service and a communication service and transmits a broadcast channel at the request of a user. In the replacement, CATV having IPTV service provision function to support user's smooth channel change and efficiently use uplink band by providing IPTV service without delay of channel change considering the DOCSIS protocol, which is the MAC protocol of CATV network. A network system and a method thereof are provided.

The current network seeks a convergence of broadcast service and communication service to support various services to users. This service model expects that various services (data, voice, and video services) are performed on one subscriber line, and by providing these various services in package form, it will contribute to attracting new subscribers and creating new profit model. .

However, broadcast services and communication services have been treated as separate areas. That is, the broadcast service is a one-way service, and transmits continuous data in all program types regardless of the user's request. On the other hand, a communication service is a bidirectional service, and transmits data at the request of a user. For example, even if the same video data is transmitted, VOD (Video-On-Demand) is treated as a communication service, while programs such as TV are treated as broadcast services.

As a representative network for simultaneously supporting such a broadcast service and a communication service, there is a CATV (Cable Television) network. The first CATV network was a unidirectional network for transmitting analog video channel data to all users, but was extended to a bidirectional hybrid fiber coaxial cable (HFC) structure as shown in FIG. 1 to simultaneously support a broadcast service and a communication service.

However, as shown in (a) of FIG. 2, the bandwidth of the CATV network having the bidirectional HFC structure is separated from each other by the bandwidth of the broadcast service and the communication service, and thus it is impossible to efficiently use the bandwidth. At this time, 5Mhz ~ 42Mhz and 500Mhz ~ 750Mhz are uplink and downlink transmission bandwidth for communication, respectively, 54Mhz ~ 450Mhz are downlink transmission bandwidth for analog broadcasting.

Therefore, in order to efficiently support a broadcast service and a communication service simultaneously on a CATV network, as shown in FIG.

The CATV network of the conventional bidirectional hybrid fiber coaxial cable (HFC) structure, in which the bandwidths of the broadcast service and the communication service are separated, transmits all channels to the user regardless of the user's needs, causing unnecessary waste of bandwidth. For example, even if there are no viewers using the 'fishing channel', the multiple system operator (MSO) transmits the 'fishing channel' to all users through the downlink band of the CATV network.

As a result, the waste of bandwidth constrains the resource utilization for the communication service, thus integrating the bandwidth of the broadcast service and the communication service as shown in FIG. 2 (b) in order to efficiently use network resources. Based on the hierarchical structure of the DOCSIS protocol extension stack as shown, a broadcast channel is replaced with an IPTV service on an IP layer transmitted according to a user's request.

In addition, in replacing a conventional broadcast service with an IPTV service, it is important to reduce a channel change delay. In other words, a mechanism for making a channel change requested by a user in an appropriate time is essential.

At this time, in order to smoothly support the IPTV service on the CATV network, the channel change delay must consider DOCSIS protocol, which is the MAC protocol of the CATV network. This is because when a user changes a channel, the transmission of information about the channel change is caused by contention of data slots, which increases the channel change delay and causes the user's channel change to not be made in a timely manner. to be.

Hereinafter, the service class of the DOCSIS protocol will be described in detail.

The DOCSIS protocol was developed based on IEEE 801.14. DOCSIS-1.0 employs a variety of technologies including virtual queues, minislots, downlink MPEG-2 formats, security modules, piggybacking, synchronization processes, and modulation schemes.

However, in case of DOCSIS-1.0, there is no quality of service (QoS) mechanism, so it is impossible to guarantee QoS according to the characteristics of data. Suggesting. In other words, DOCSIS-1.1 is designed to be more sensitive to QoS guarantees. In particular, the classification of five service classes according to the characteristics of data becomes the most important factor in providing QoS.

The five service classes include unsolicited grant service (UGS), unsolicited grant service-activity detection (UGS-AD), real-time polling service (rtPS), non real-time polling service (nrtPS), and best effort (Be). In the present invention described below, only the UGS service class and the rtPS service class suitable for transmitting the user's channel change request information to the cable mode termination system (CMTS) within an appropriate time period are considered.

USG service class is a service class defined to support real-time traffic flow that periodically generates fixed size packets such as Voice over IP (VoIP). By periodically assigning to (Cable Modem), it is possible to eliminate the delay and overhead caused by slot contention and admission process.

However, if there is no data to transmit, bandwidth is wasted.

The rtPS service class is a service class that supports real-time traffic that periodically generates variable length data packets such as MPEG video, and a user wants without contention due to being allocated a request slot that is periodically provided as shown in FIG. You can request a data slot of size, which allows you to send real-time data.

The rtPS service class can utilize the bandwidth of uplink transmission more effectively than the UGS service class, but has a disadvantage of causing a relatively long delay time after the request.

In the proposed IPTV system, since the channel change information of the user includes only information about a new channel requested by the user, the size of information to be delivered is constant. Since such channel change information should be transmitted as soon as possible, a low delay UGS service class is suitable, and for this reason, it is preferable that a dynamic channel management mechanism uses a UGS service class on a DOCSIS CATV network.

As a result, it is important to reduce channel change delays in disseminating IPTV services. In other words, a mechanism for making a channel change requested by a user in an appropriate time is essential.

Some conventional techniques for solving this problem will be described.

According to 'Chunglae Cho', 'Intak Han', 'Yongil Jun' and 'Hyeongho Lee', entitled 'Improvement of Channel Zapping Time in IPTV Services Using the Adjacent Groups Join-Leave Method', 'Advanced Communication Technology 2004, vol. 2 (pp. 971-975, 2004.) suggests a mechanism for reducing channel change delay by sending additional channels in advance in addition to the channel the user is currently watching. That is, when the user requests the adjacent channel of the channel currently being watched, the user can watch the requested adjacent channel without network delay.

'J.M. Boyce ',' A. M. Tourapis', entitled "Fast efficient channel change [set-top box applications]". The prior art, published in 2005 Digest of Technical Papers (pp. 1-2, Jan. 2005), proposes a system that can reduce the decoding delay and increase the efficiency of video coding. That is, the encoder periodically encodes I frames encoded with low bits and transmits them with general image frames. Therefore, when the user requests a new channel, the decoder performs a fast decoding using a low bit encoded I frame without reducing the decoding delay without having to wait for the I frame of a general video frame.

By 'Jaegwan Kim', 'Hyunho Yun', 'Minho Kang', 'TaeYeon Kim', 'Jungju Yoo', titled "Performance evaluation of channel zapping protocol in broadcasting services over hybrid WDM-PON" , vol. 2 (pp. 1152-1155, Feb. 2005.) proposes a method for reducing channel change delay by reducing GQI (General Query Interval) of IGMP parameters. That is, since the GQI is related to the join processing time of the channel multicast group, adjusting the GQI enables fast channel change.

Prior art, published by ICF 2004, vol. 3 (pp.2075-2078, Oct. 2004.), entitled "Increasing bandwidth utilization in next generation IPTV networks" by "Ulf Jennehag" and "Tingting Zhang". Has proposed a system that can improve bandwidth efficiency by reducing the number of synchronization frames compared to GOP encoding, and the proposed system can reduce decoding delay by increasing the frequency of synchronization frames.

These conventional techniques (algorithms) do not consider the characteristics of the CATV network at all, there is a problem that can not be applied directly on the CATV network.

The present invention has been proposed to solve the above problems, and it is a MAC protocol of CATV network in integrating bandwidth of broadcast service and communication service and replacing broadcast channel with IPTV service on IP layer transmitting by user's request. By providing an IPTV service without delay of channel change in consideration of the DOCSIS protocol, the present invention provides a CATV network system and a method for providing a CATV network system having an IPTV service providing function to support user's smooth channel change and to efficiently use an uplink band. There is this.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

An apparatus of the present invention for achieving the above object is a CATV network system having an IIPTV service providing function, receiving all channel data from a broadcast server, integrating the bandwidth of the broadcast service and the bandwidth of the communication service, Based on the hierarchical structure of the DOCSIS protocol extension stack, which is a MAC protocol, it provides the channel data requested from the cable modem (CM) without delay of channel change, but when operating in the continuous channel change mode, the channel currently being watched by the user (' A cable modem termination device for previously transmitting an adjacent channel ('first adjacent channel') of the current channel 'according to an uplink allocation interval (Grant Interval); And a plurality of cable modems for requesting specific channel data from the cable modem end device and receiving the corresponding channel data.

On the other hand, in the method of the present invention, in a method for providing an IPTV service in a CATV network system, the cable modem end device receives all channel data from the broadcast server, integrates the bandwidth of the broadcast service and the bandwidth of the communication service, Based on the hierarchical structure of the DOCSIS protocol extension stack, which is a MAC protocol of the MAC protocol, provides the channel data requested from the cable modem (CM) without delay of channel change, and when operating in the continuous channel change mode, the channel currently being viewed by the user ( A channel data providing step of previously transmitting an adjacent channel ('first adjacent channel') of the 'current channel' according to an uplink allocation interval (Grant Interval); And requesting, by the cable modem, specific channel data to the cable modem end device, and receiving the corresponding channel data.

In addition, the present invention proposes a broadcast service structure for an efficient IPTV service on a DOCSIS CATV network, and proposes a dynamic channel management mechanism for smoothly changing a channel while using network resources efficiently under such a structure.

In addition, in the present invention, the information on the channel change request of the user is transmitted to the CMTS by the UGS service class.

In addition, in the present invention, broadcast channel data is provided in the form of IPTV service, and the bandwidth of broadcast and communication is integrated on a DOCSIS CATV network.

In addition, an element that can be controlled in the present invention is the network management part.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art may easily implement the technical idea of the present invention. There will be. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

6 is a configuration diagram of an embodiment of a CATV network system having an IPTV service providing function according to the present invention.

As shown in FIG. 6, the CATV network system having an IPTV service providing function according to the present invention receives all channel data from a broadcast server, integrates the bandwidth of the broadcast service with the bandwidth of the communication service, and provides the MAC of the CATV network. Based on the hierarchical structure of the DOCSIS protocol extension stack, which is a protocol, specific channel data is requested to the CMTS (Cable Modem Termination System) 61 and CMTS to provide corresponding channel data requested from a cable modem (CM) without delay of channel change. And a plurality of cable modems (CMs) 62 for receiving corresponding channel data.

Hereinafter, an IPTV service providing process in a CATV network system will be described with reference to FIG. 7.

As shown in (a) of FIG. 7, a conventional CATV network system transmits all channel data to a user, while a CATV having an IPTV service providing function according to the present invention is illustrated as shown in (b) of FIG. 7. Since the network system transmits only some channel data related to the user's request, there is an advantage that the extra bandwidth can be used for services other than broadcasting.

At this time, the channel data that the user wants to watch should be transferred by switching in the CMTS 61. For this purpose, the bandwidth of the broadcast service and the bandwidth of the communication service are integrated, and the hierarchical structure of the DOCSIS protocol extension stack, which is the MAC protocol of the CATV network, is provided. Based on this, the user's viewing channel information and status are quickly transmitted to the CMTS 61 without delay.

Here, the delay for the channel change is made up of the user's command processing time, network delay, and decoding delay.

First, the user's command processing time means the user's channel change request and the time until this information is transmitted in the upband on the CATV network.

Next, the network delay means a time from when the channel change information is transmitted to the CMTS 61 until the first packet for the requested channel is delivered to the user.

Finally, the decoding delay refers to the delay time from the arrival of the first (I) frame required for displaying the image to the user and displayed on the imaging apparatus.

In this case, since the command processing time and the decoding delay are related to the performance of the user system and the video coding algorithm, respectively, these two factors cannot be adjusted through network management.

As a result, an element that can be accessed from a network point of view is network delay, and the present invention enables efficient channel switching by reducing network delay.

Hereinafter, the channel change delay will be described in detail with reference to FIG. 8.

As shown in FIG. 8, the channel change delay depends on the Grant Interval (GI) of the UGS service class. In FIG. 8 (a), it can be seen that the user's channel change request occurs at 2ms, and this information is transmitted to the CMTS 61 through the uplink at 50ms. That is, since the GI is 50ms, after waiting 48ms, the channel change request information of the user may be transmitted to the CMTS 61 through the upband.

On the other hand, if the GI is 10ms as shown in (b) of FIG. 8 and is smaller than that of FIG. 8 (a), the channel change request information of the user may be transmitted to the CMTS 61 immediately after waiting only 8 ms. As a result, network costs increase from 20 / sec to 100 / sec.

In view of this, the present invention considers such network cost and channel delay at the same time.

In other words, if most of the uplink transmission bandwidth is used for such a broadcasting service, the user can smoothly change the channel, while the bandwidth for the communication service is relatively reduced, thereby minimizing the network cost for the broadcasting service. By transmitting the channel change request information of the user to the uplink as soon as possible, it is possible to reduce the uplink bandwidth for unnecessary broadcast services and to support efficient communication services.

Meanwhile, the user's channel change can be classified into a continuous channel change and an arbitrary channel change. Continuous channel change means a request for an adjacent uplink or downlink channel of the channel that the user is currently watching. In other words, if the user is currently watching channel 10, the next new channel request will be channel 9 or 11.

In case of random channel change, the user's channel selection is random in the new channel request.

The present invention is to determine the GI that satisfies Equation 1 below, and the number of adjacent channels (AC _new ) additionally transmitted for the current channel when the continuous channel is changed.

Cost (GI),

Constraints (1): Dc (GI) ≤ DBc

Constraints (2): Dr (GI) ≤ DBr

Here, Cost (GI) means network cost for GI of UGS service class, Dc (GI) and Dr (GI) mean continuous channel change delay and random channel change delay for a given GI, respectively. DBr means a threshold value of the continuous channel change delay and the random channel change delay, respectively.

In the continuous channel change situation, it is easy to predict which channel the user will select, and thus, by transmitting several adjacent channels in advance in an appropriate time in addition to the channel currently being watched by the user, the channel change delay felt by the continuous channel change is reduced. You can. At this time, reduce the GI or increase the AC _{new so} that the continuous channel change delay does not exceed DBc.

Referring to FIG. 9, a channel change management process in a continuous channel change situation will be described.

As shown in FIG. 9, D _trans is a network delay and D _dec is a decoding delay. In this case, GIc is called GI for continuous channel change.

Initially, the user is watching channel n, and three adjacent channels (n + 1, n + 2, n + 3) are transmitted together.

Since, t ₂ In response to the channel request at that point in time, the user receives additional adjacent channels (n + 4, n + 5) for the current channel from the CMTS 61 at time t _{4 and} at time t ₅ due to the decoding delay. The image of the channel n + 4 is output to the display device.

At this time, since the channels (n + 1, n + 2, n + 3) are already transmitted to the user at time t ₁ , the channel change delay for this time takes only D _dec, while the channel (n + 4) The change delay takes t ₅ -t ₃ . In order for such a continuous channel change delay to satisfy the constraint (1) of Equation 1, Equation 2 below must be established.

Here, t ₂ - t ₁ has a value between 0 GI _C, t ₂ in consideration of the worst case - if there be expressed as shown in Equation 3] t ₁ to set a GI _C.

Here, 3 means the number of adjacent channels with respect to the current channel, and this is expressed as Equation 4 below.

Here, AC is represented by the sum of AC _old and AC _new as shown in Equation 5 below, where AC _old and AC _new are additionally transmitted and the number of adjacent channels provided for the current channel, respectively. It means the number of adjacent channels.

In order to satisfy the above Equation 5 and minimize the network cost, the GIc has to have a large value as much as possible, and thus has a relationship as shown in Equation 6 below.

Here, the meaning of [Equation 6] is as follows.

If the user has a large number of adjacent channels for the current channel, the user's GIc is set large so that unnecessary continuous channel change information is not transmitted. On the other hand, when the number of adjacent channels available to the user is small, the GIc is set small so that the user can react to the channel change request of the user and transmit broadcast data in a timely manner.

The relationship between AC, GIc, and Cost (GIc) is shown in Equation 7 below.

At this time, if AC is set too small, the GIc must be very small accordingly. However, if the GIc is set too small, a large amount of uplink bandwidth is required, which is not preferable because the uplink transmission efficiency of other services is lowered.

Therefore, we define GIm, which is the minimum value that GIc can have, and if the adjusted GIc is less than or equal to GIm, AC _new is increased a little so that the GIc can always keep above the allowable value.

The pseudo code for the algorithm for determining GI and AC _new for minimizing Cost (GI) while satisfying the constraint (1) in the continuous channel situation is shown in Table 1 below.

So far only continuous channel changes have been considered.

In the case of random channel change, it is difficult to predict which channel the user selects, and thus it takes more time to process the channel, so that the continuous channel change delay should be below DBr to support the user's smooth channel change. give. At this time, DBr has a larger value than DBc.

That is, in order to satisfy the constraint (2) of Equation 1, Equation 8 below must be established.

Here, GIr means GI for a random channel change, and as in the continuous channel change, the GIr is set as large as shown in [Equation 9] below, thereby making the bandwidth for uplink transmission available for other services. .

In the present invention, GIr is set smaller than GIc, and has a relationship as shown in Equation 10 below.

Since only one GI can be assigned to one user, to satisfy the constraints (1) and (2) at the same time, the smaller one of GIc and GIr is assigned to the user as shown in Equation 11 below.

Hereinafter, a performance of channel change delay of a CATV network system having an IPTV service providing function according to the present invention will be described with reference to FIG. 10.

As shown in (a) of FIG. 10, all delays for continuous channel change by the user are equal to or less than DBc, and most channel change delays are concentrated around 60 ms. This is because, in addition to the channel requested by the user, by additionally transmitting adjacent channels in advance, when the user requests the adjacent channel of the channel currently being viewed, only D _dec is required without a network delay before outputting the requested channel to the display device. .

Similarly, even when only a random channel change is taken into account, all delays for a user's random channel change are less than or equal to DBr. The reason is that the delay for some arbitrary channel change becomes 60ms even if the adjacent channel is not sent in advance, because the random channel requested by the user is already watched by another user and is already transmitted on the CATV. At this time, the average GI of the user was measured 312ms, so the average network cost was 3.2.

10B illustrates a case where the channel management method according to the present invention is not applied.

As in FIG. 10A, the GI is set to 312 ms and the GI and the AC _new are not adjusted. Although the same network cost is used, the average channel change delay is increased by 68 ms than in the case of FIG. 10A, and it can be seen that the continuous channel change delay and random channel change delay of most users are out of the specified delay thresholds. have.

Through this, it can be seen that the present invention efficiently supports the uplink band on the CATV network while supporting the user's smooth channel change.

Meanwhile, the QoS (packet loss and delay time) performance of the present invention was also tested.

The experimental environment is the same as the above experiment. When the amount of traffic flowing from the non-real-time server to the CATV network is large enough to cause packet loss, the QoS performance of the existing broadcasting system and the proposed broadcasting system is analyzed and additionally, WFQ Performance measurement was performed according to the application of the down scheduler.

The WFQ downlink scheduler used in the experiment classifies incoming packets into three classes (broadcast data, real-time data, and non-real-time data) based on the type of service (TOS) value. Each enters.

Since broadcast data is the data that should be serviced first, the highest weight is assigned to guarantee timely processing with minimum loss and delay, and the lowest priority weight is assigned because non real-time data is not sensitive to time delay. do.

[Tables 2] and [Table 3] below show a conventional broadcast system without WFQ downlink scheduling, a conventional broadcast system with WFQ downlink scheduling, a broadcast system with no WFQ downlink scheduling, and a WFQ downlink. The packet loss rate and transmission delay of the broadcasting system according to the present invention are measured.

As can be seen from [Table 2], the proposed broadcasting system can efficiently use the downlink band of the CATV network for the broadcast service, so that the extra downlink band can be used for other services, and thus, compared with other cases. It shows a lower packet loss rate.

In particular, in the case of the proposed broadcasting system using WFQ downlink scheduling, the packet loss due to overflow of CTMS is limited to non-real-time data through WFQ downlink scheduling.

Similarly, it can be seen from Table 3 that similar results are shown in terms of transmission delay. That is, the proposed system shows better performance in terms of packet loss rate and transmission delay than the existing system.

In addition, when WFQ downlink scheduling is applied to the proposed system, stable broadcasting service can be provided to the user.

As described above, the method of the present invention may be implemented as a program and stored in a recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.) in a computer-readable form. Since this process can be easily implemented by those skilled in the art will not be described in more detail.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by the drawings.

As described above, the present invention integrates the bandwidth of a broadcast service and a communication service and replaces a broadcast channel with an IPTV service on an IP layer that is transmitted by a user's request, and considers a DOCSIS protocol that is a MAC protocol of a CATV network. By providing an IPTV service without change delay, it is possible to efficiently support the user's channel change and to efficiently use the uplink band.

Claims (8)

In a CATV network system having an IPTV service providing function, Receive all channel data from the broadcast server, integrate the bandwidth of the broadcast service with the bandwidth of the communication service, and from the cable modem (CM) without delay of channel change based on the hierarchical structure of the DOCSIS protocol extension stack, which is the MAC protocol of the CATV network. Providing the requested channel data, when operating in the continuous channel change mode, the first channel comprising a predetermined number of N channels (N is one or more natural numbers) among the channels adjacent to the current channel currently viewed by the user. A cable modem termination device for previously transmitting an adjacent channel according to an uplink allocation interval (Grant Interval); And A plurality of cable modems for transmitting channel request data to the cable modem end device and receiving the current channel and the first adjacent channel data; CATV network system having an IPTV service providing function comprising a. The method of claim 1, The cable modem termination device, In the case of the UGS (Unsolicited Grant Service) service class, a predetermined number of M channels (M is a natural number of 1 or more) among channels adjacent to the changed current channel upon receiving the channel request data indicating the change of the current channel from the cable modem. CATV network system having an IPTV service providing function, characterized in that for additionally transmitting the second adjacent channel by adjusting the number of the second adjacent channel (AC _new ). The method of claim 2, The cable modem termination device, CATV network system having an IPTV service providing function, characterized in that as the number of the first adjacent channel increases the number of the second adjacent channel (AC _new ). The method of claim 2, The cable modem termination device, CATV network system having an IPTV service providing function, characterized in that the number of the second adjacent channel (AC _new ) increases as the number of the first adjacent channel decreases. In the method of providing IPTV service in a CATV network system, The cable modem end device receives all channel data from the broadcast server, integrates the bandwidth of the broadcast service with the bandwidth of the communication service, and based on the hierarchical structure of the DOCSIS protocol extension stack, which is the MAC protocol of the CATV network, Provides the channel data requested from the modem (CM), but when operating in the continuous channel change mode, the predetermined number of N channels (N is a natural number of 1 or more) among the channels adjacent to the current channel being viewed by the current user. A channel data providing step of previously transmitting a first adjacent channel including the channel according to an uplink allocation interval; And The cable modem transmitting channel request data to the cable modem end device and receiving the current channel and the first adjacent channel data IPTV service providing method in a CATV network system comprising a. The method of claim 5, wherein the channel data providing step, In the case of the UGS (Unsolicited Grant Service) service class, a predetermined number of M channels (M is a natural number of 1 or more) among channels adjacent to the changed current channel upon receiving the channel request data indicating the change of the current channel from the cable modem. And adjusting the number of second neighboring channels (AC _new ), which additionally transmits the second neighboring channels. The method of claim 6, The channel data providing step, And increasing the number of second adjacent channels (AC _new ) as the number of the first adjacent channels increases. The method of claim 6, The channel data providing step, And increasing the number of second adjacent channels (AC _new ) as the number of first adjacent channels decreases.

Images