Distribution device, program, and method for distributing content using multiple distribution streams

Abstract

A distribution device and the like are provided that, for real-time broadcasting services, determines an optimal distribution method stream when the distribution device distributes content to terminals via a base station. [Solution] A distribution device distributes content to multiple terminals via base stations using multiple distribution method streams, and for each base station, stores a modulation index kn determined for each terminal. For each base station, distribution is performed using a first distribution method stream to terminals having a modulation index kn equal to or greater than a predetermined modulation index kc, and distribution is performed using a second distribution method stream to terminals having a modulation index kn lower than the predetermined modulation index kc. The first distribution method stream is distributed using broadcast or multicast, and the second distribution method stream is distributed using unicast.

Description

[Technical Field]

[0001] The present invention relates to a technology for a distribution device in IP broadcasting (Internet Protocol). [Background technology]

[0002] An example of a distribution device for IP broadcasting is a core system device that relays between a content server and a base station. An example of a core system device is an MBS (Multi-Broadcast Service). The MBS receives content for multiple channels from a content server in a BMSC (Broadcast Multicast Service Center). The core system device then distributes the content to multiple terminals (User Equipment) via the base station. Stream distribution methods include broadcast, multicast, and unicast.

[0003] For example, in the case of cable television businesses, the installation of a viewing environment requires the laying of lead-in cables to users' homes. For example, the more 4K and 8K video broadcasts become popular, the higher the costs of broadband installation within buildings, especially in apartment complexes. For this reason, "local IP broadcasting" using mobile communication systems is being considered for cable television businesses as an alternative to lead-in cables. High transmission quality can be ensured by using 5G, 4G, or even 6G in the future for local IP broadcasting.

[0004] Conventionally, there is a technology in which a core system device broadcasts content for a real-time broadcasting service in accordance with a wireless modulation method between a base station and a terminal (see, for example, Patent Document 1). According to this technology, the core system device collects modulation indices (MCS (Modulation and Cording Scheme)) of wireless modulation methods determined according to the wireless transmission path for each terminal, and determines, for each viewing channel, a statistical wireless modulation method that serves as a statistical value from multiple wireless modulation methods. The core system device then transmits a content request including the viewing channel and the statistical wireless modulation method to a content server. In response, the content server transmits the content of the viewing channel included in the content request to the core system device at a bit rate according to the statistical wireless modulation method. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7039155 Summary of the Invention [Problem to be solved by the invention]

[0006] The technology of Patent Document 1 is applied to a "storage-based broadcasting service" in which broadcasted content is completely stored in a terminal and then played back. On the other hand, cable television businesses are considering a "real-time broadcasting service" in which content received by terminals is played back immediately. To achieve this, local IP broadcasting distributes content via broadcast or multicast, and distributes individual data missing from terminals via unicast. However, in the case of real-time broadcasting services, it is difficult for a distribution device to determine the optimal distribution stream when distributing content to terminals via a base station.

[0007] Therefore, the present invention aims to provide a distribution device, program, and method that can determine the optimal distribution format stream when a distribution device distributes content to a terminal via a base station for a real-time broadcasting service. [Means for solving the problem]

[0008] According to the present invention, there is provided a distribution device that distributes content to a plurality of terminals via a base station using a plurality of distribution method streams, the distribution device comprising: For each base station, a modulation index kn determined for each terminal is stored, For each base station, a first transmission method stream is transmitted to a terminal having a modulation index kn equal to or greater than a predetermined modulation index kc; For each base station, a second transmission method stream is transmitted to a terminal having a modulation index kn lower than a predetermined modulation index kc. It is characterized by:

[0009] According to another embodiment of the distribution device of the present invention, a first required bandwidth calculation means for calculating a first required bandwidth Wc at a modulation index kc of a stream in a first delivery method; a second total required bandwidth calculation means for calculating a second total required bandwidth Wn for all terminals having a modulation index kn lower than the modulation index kc of the first delivery method stream; a modulation index determination means for determining a modulation index kc of a first delivery method stream, the modulation index kc being such that a total required bandwidth W obtained by adding the first required bandwidth Wc and the second total required bandwidth Wn satisfies a predetermined bandwidth condition, among a plurality of modulation indices kc of the first delivery method stream; It is also preferred that the

[0010] According to another embodiment of the distribution device of the present invention, The modulation index determination means determines, as a predetermined band condition, a modulation index kc that minimizes the required total band W, or a modulation index kc that makes the required total band W smaller than a predetermined threshold. It is also preferable.

[0011] According to another embodiment of the distribution device of the present invention, The first required bandwidth calculation means calculates a first required bandwidth Wc (=b / log2kc) for the stream in the first distribution format by dividing the content bit rate b by the number of codeword bits based on the modulation index kc. It is also preferable.

[0012] According to another embodiment of the distribution device of the present invention, The modulation index determining means The lower the modulation index kc of the first distribution method stream, the smaller the number of codeword bits and the larger the first required bandwidth Wc. The higher the modulation index kc of the first distribution method stream, the larger the number of codeword bits and the smaller the first required bandwidth Wc. In the above, a modulation index kc of the first distribution method stream is determined so that the total required bandwidth W satisfies the predetermined bandwidth condition. It is also preferable.

[0013] According to another embodiment of the distribution device of the present invention, the first required bandwidth calculation means calculates a first required bandwidth Wc (=m(t)·b / log2kc(t)) by further multiplying the first required bandwidth Wc by the number of channels m(t) to be simultaneously distributed in a time period t; The modulation index determining means The larger the number of channels m(t), the larger the first required bandwidth Wc becomes. The smaller the number of channels m(t), the smaller the first required bandwidth Wc. In the above, a modulation index kc of the first distribution method stream is determined so that the total required bandwidth W satisfies the predetermined bandwidth condition. It is also preferable.

[0014] According to another embodiment of the distribution device of the present invention, The second total required bandwidth calculation means calculates a second individual bandwidth (= b / log2kn) obtained by dividing the content bit rate b by the number of codeword bits based on the modulation index kn of the stream in the second distribution method, and sums it with the number of viewing households n(t) (= total number of households N × viewing rate q(t)) in the time slot t to obtain a second total required bandwidth (= Σ i=1~n N bi / log2kni(t) The modulation index determining means The larger the number of viewing households n, the larger the second required total bandwidth Wn. The smaller the number of viewing households n, the smaller the second required total bandwidth Wn. In the first distribution method, a modulation index kc of the stream is determined so that the total required bandwidth W satisfies the predetermined bandwidth condition. It is also preferable.

[0015] According to another embodiment of the distribution device of the present invention, The first delivery method stream is delivered by broadcast and the second delivery method stream is delivered by unicast, or The first delivery method stream is delivered by multicast, and the second delivery method stream is delivered by unicast, and also delivered by unicast to terminals that have not sent a multicast join request. It is also preferable.

[0016] According to another embodiment of the distribution device of the present invention, The distribution device is a core system device that functions as an MBS (Multi-Broadcast Service) and is connected between a content server that transmits content from multiple channels and a base station that distributes content to multiple terminals in a real-time broadcasting service. It is also preferable.

[0017] According to another embodiment of the distribution device of the present invention, the core system device transmits to the content server a content request including the modulation index kc of the first delivery method stream determined by the modulation index determination means, and transmits to the content server each content request including each modulation index kn of the second delivery method stream; Receives content with a bit rate corresponding to each modulation index included in each content request from the content server and distributes it to the base station. It is also preferable.

[0018] According to the present invention, there is provided a program for causing a computer installed in a device that distributes content to a plurality of terminals via a base station using a plurality of distribution method streams, the program comprising: For each base station, a modulation index kn determined for each terminal is stored, For each base station, a first transmission method stream is transmitted to a terminal having a modulation index kn equal to or greater than a predetermined modulation index kc; For each base station, a second transmission method stream is transmitted to a terminal having a modulation index kn lower than a predetermined modulation index kc. The present invention is characterized in that the computer functions as follows.

[0019] According to the present invention, there is provided a distribution method for a device that distributes content to a plurality of terminals via a base station using a plurality of distribution method streams, the method comprising: The device is For each base station, a modulation index kn determined for each terminal is stored, For each base station, a first transmission method stream is transmitted to a terminal having a modulation index kn equal to or greater than a predetermined modulation index kc; For each base station, a second transmission method stream is transmitted to a terminal having a modulation index kn lower than a predetermined modulation index kc. The method is characterized in that it is executed as follows. [Effects of the Invention]

[0020] According to the distribution device, program, and method of the present invention, when a distribution device distributes content to a terminal via a base station for a real-time broadcasting service, it is possible to determine the optimal distribution format stream. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a system configuration diagram of local IP broadcasting according to the present invention. [Figure 2] FIG. 2 is a diagram showing the basic functional configuration of a core system device according to the present invention. [Figure 3] FIG. 2 is an explanatory diagram of a coverage area of ​​a broadcast wave in the present invention. [Figure 4] FIG. 2 is a functional configuration diagram of a distribution control unit according to the present invention. [Figure 5] FIG. 2 is an explanatory diagram showing the relationship between the modulation index and the total bandwidth in the present invention. [Figure 6] FIG. 2 is a sequence diagram of the entire system according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0023] FIG. 1 is a diagram showing the system configuration of local IP broadcasting according to the present invention.

[0024] 1 shows a system that applies IP broadcasting to a cable television network. This system includes a distribution device 1, a content server 2, a base station 3, and a terminal 4. Local IP broadcasting is applied between the distribution device 1 and the terminal 4 via the base station 3.

[0025] <Content Server 2> The content server 2 is a real-time broadcasting service that transmits content in response to a content request from the distribution device 1. When the distribution device 1 is an MBS, the content server 2 functions as a BMSC.

[0026] The content server 2 transmits the content (segment series) to the distribution device 1 based on, for example, MPEG-DASH (Dynamic Adaptive Streaming over HTTP). MPEG-DASH is an adaptive HTTP (HyperText Transport Protocol) streaming protocol for the Internet. This means that a CDN (Contents Delivery Network), which is used to speed up and scale up websites, can be used directly, without the need for a separate video distribution server. Adaptive streaming also makes it possible to dynamically switch video quality, ensuring stable distribution.

[0027] <Base station 3> The base station 3 broadcasts the content received from the distribution device 1 to multiple terminals 4 as a local IP broadcast. Each base station synchronizes content with radio resources assigned by an MCE (Multi-Cell Multicast Coordination Entity), and broadcasts the content simultaneously using an MBSFN (MBS Single Frequency Network) transmission method.

[0028] <Terminal 4> The terminal 4 transmits a user-desired "viewing channel" to the distribution device 1 via the base station 3. The viewing channel may be transmitted between the terminal 4 and the distribution device 1 based on a C (Control) plane connection. Then, the terminal 4 receives the content via a wireless transmission path from the base station 3. At this time, the terminal 4 performs RF (Radio Frequency) synthesis on the radio waves received from the base station 3, and reproduces the content for the user.

[0029] FIG. 2 is a diagram showing the basic functional configuration of the core system device in the present invention.

[0030] <Distribution Device 1> The distribution device 1 is based on a real-time broadcasting service and distributes content of multiple channels received from a content server 2 to multiple terminals 4 via a base station 3. As a feature of the present invention, the distribution device 1 is a core system device and functions as an MBS (Multi-Broadcast Service).

[0031] The distribution device 1 distributes content in a plurality of "distribution method streams" to a plurality of terminals 4 via the base station 3. Examples of the distribution method streams are as follows. First delivery method stream: Broadcast (one-to-an unspecified number of broadcasts, no need to specify a device) Multicast (one-to-many broadcasting, targeted at joined devices) Secondary delivery stream: Unicast (one-to-one communication) Regardless of the delivery method, the stream is delivered as MPEG-DASH at the highest layer. By making the content segment length relatively short, it can be used for real-time broadcasting services.

[0032] 2, the distribution device 1 includes a distribution control unit 10, a first distribution unit 11, and a second distribution unit 12. These functional components are realized by executing a program that causes a computer installed in the distribution device to function. The processing flow of these functional components can also be understood as a distribution method of the device.

[0033] [Distribution control unit 10] The distribution control unit 10 collects and stores the modulation index kn determined for each terminal 4 from each base station 3. The modulation index kn changes over time depending on the state of the wireless transmission path between the base station 3 and the terminal 4. Furthermore, the distribution control unit 10 receives a viewing channel from the terminal 4 based on a C (Control) plane connection.

[0034] The distribution control unit 10 controls the distribution method stream as follows. For each base station 3, a stream in the first distribution method is distributed to a terminal having a modulation index kn equal to or greater than a predetermined modulation index kc. For each base station 3, a stream in the second distribution method is distributed to terminals having a modulation index kn lower than a predetermined modulation index kc.

[0035] [First Distribution Section 11] The first distribution unit 11 transmits a content request for the user's viewing channel to the content server 2. At this time, the content request also includes a predetermined modulation index kc instructed by the distribution control unit 10. Content request (viewing channel, modulation index kc) In response to this, the first distribution unit 11 receives from the content server 2 content based on a predetermined modulation index kc in the user's viewing channel. Then, the first distribution unit 11 distributes the content to a plurality of terminals 4 via the base station 3 using a first distribution method stream (broadcast or multicast). The content of the stream in the first distribution format can be received by a terminal 4 having a modulation index kn that is equal to or greater than a predetermined modulation index kc.

[0036] The first distribution unit 11 distributes content to the terminal 4 via the base station 3 based on FLUTE (File Delivery over Unidirectional Transport) or ROUTE (Real-time Object Delivery over Unidirectional Transport) of MBS. FLUTE and ROUTE specify file transfer via a one-way transmission protocol. This technology is transmitted in seconds and played in real time. Buffering of segments introduces a delay of a few seconds, but video playback is supported by standard browsers.

[0037] [Second Distribution Section 12] The second distribution unit 12 distributes the user's viewing channel using a second distribution method stream (unicast) to terminals 4 having a modulation index kn lower than a predetermined modulation index kc instructed by the distribution control unit 10. The second distribution unit 12 receives a "unicast distribution request" for the viewing channel from a terminal 4 in which data loss has occurred in the first distribution method stream (broadcast or multicast). At that time, the second distribution unit 11 transmits a content request for the user's viewing channel to the content server 2 based on the modulation index kn of the terminal 4. In response to this, the second distribution unit 12 receives from the content server 2 content based on a predetermined modulation index kn in the user's viewing channel. Then, the second distribution unit 12 distributes the content to the terminal 4 via the base station 3 in a second distribution format stream (unicast).

[0038] Terminal 4 receives content corresponding to the viewing channel from distribution device 1 using a first distribution method stream (broadcast or multicast). At this time, terminal 4 detects whether data loss has occurred. When detecting data loss, terminal 4 sends a "unicast distribution request" for the viewing channel to distribution device 1. In response, second distribution unit 12 of distribution device 1 distributes the content of that viewing channel using a second distribution method stream (unicast).

[0039] When the distribution device 1 distributes a first distribution method stream by broadcast, it targets a second distribution method stream to terminals 4 having a modulation index kn lower than a predetermined modulation index kc. In other words, the second distribution unit 12 will not distribute content by unicast to terminals 4 unless it receives a unicast distribution request from the terminal 4. As a result, content will be distributed by unicast to terminals 4 having a modulation index kn lower than the predetermined modulation index kc.

[0040] Furthermore, when the distribution device 1 distributes the first distribution method stream by multicast, the second distribution method stream is targeted to terminals 4 that have a modulation index kn lower than a predetermined modulation index kc and terminals 4 that have not sent a multicast join request (have not joined). Of these, the distribution device 1 transmits the content by unicast to terminals 4 that have sent a unicast distribution request.

[0041] Note that even if terminal 4 is receiving content via unicast, it may be able to receive the same content via broadcast. In other words, it enters a "simulcast" distribution state. Distribution device 1 distributes the same content via both broadcast and unicast with different modulation indices kc and kn.

[0042] FIG. 3 is an explanatory diagram of the coverage area of ​​the broadcast wave in the present invention.

[0043] FIG. 3 shows the width of the coverage area of ​​the broadcast wave according to the modulation index kc of the content distributed in the first distribution stream (broadcast or multicast).

[0044] Figure 3(a) shows a case where the modulation index kc of content distributed by broadcast or multicast is low (low-order modulation). The lower the modulation index kc, the weaker the wireless modulation method, the fewer bits transmitted per symbol, and the lower the broadcast quality. This allows only a low transmission rate to be achieved, but increases noise resistance and the coverage area of ​​the broadcast wave becomes wider. On the other hand, the lower the modulation index kc of the content, the wider the bandwidth required for broadcast or multicast. This means that the total bandwidth required for unicast cannot be made wide.

[0045] Figure 3(a) shows the case where the modulation index kc of content distributed by broadcast or multicast is high (high-order modulation). The higher the modulation index kc, the more advanced the wireless modulation method, the more bits transmitted per symbol, and the better the broadcast quality. This allows for a high transmission rate, but reduces noise resistance and narrows the coverage area of ​​the broadcast wave. On the other hand, the higher the modulation index kc of the content, the narrower the bandwidth required for broadcast or multicast. This allows for a wider total bandwidth required for unicast.

[0046] The coverage rate of the first delivery method stream is expressed as P(kc(t)), where kc(t) is the modulation index in time period t. In contrast, the coverage rate of the second delivery method stream is expressed as 1-P(kc(t)). Furthermore, out of the total number of households N, the number of households that cannot be covered by the first required bandwidth of the stream in the first delivery format is expressed as N(1-P(kc(t))).

[0047] FIG. 4 is a functional block diagram of the distribution control unit of the present invention.

[0048] The distribution control unit 10 in FIG. 4 includes a modulation index storage unit 100, a first required bandwidth calculation unit 101, a second total required bandwidth calculation unit 102, and a modulation index determination unit 103.

[0049] [Modulation index storage unit 100] The modulation index storage unit 100 stores the wireless modulation scheme kn determined for each terminal 4.

[0050] The modulation index kn is determined by adaptive radio link control between the base station 3 and the terminals 4. Specifically, when establishing a radio link between the base station 3 and the terminals 4, the base station 3 transmits a pilot signal to the terminals 4, and each terminal 4 detects the received signal strength. Then, each terminal 4 transmits the received signal strength to the base station 3. The base station 3 determines the modulation index of the radio modulation scheme for each terminal 4 based on the received signal strength. Assume that eight terminals 4 are viewing one channel. In this case, for example, 3, 5, 10, 8, 9, 4, 5, and 4 are collected as modulation indices (MCS indices) for each terminal 4.

[0051] The higher the received strength of the pilot signal at terminal 4, the higher the modulation index that can be received is selected. On the other hand, the lower the received strength of the pilot signal at terminal 4, the lower the modulation index that can be received is selected.

[0052] [First required bandwidth calculation unit 101] The first required bandwidth calculation unit 101 calculates the first required bandwidth Wc at the modulation index kc of the first distribution format stream. Here, the first required bandwidth calculation unit 101 calculates the first required bandwidth Wc for the first distribution method stream (broadcast or multicast) by dividing the content bit rate b by the number of codeword bits based on the modulation index kc. Wc=b / log2kc b: content bit rate kc: modulation index of the content delivered in the first delivery method stream log2kc: number of codeword bits That is, the smaller the number of codeword bits log2kc, the larger the first required bandwidth Wc.

[0053] The first required bandwidth calculation unit 101 may also calculate the first required bandwidth Wc by further multiplying it by the number of channels m(t) that are simultaneously distributed in the time period t. Wc(t)=m(t)·b / log2kc(t)

[0054] [Second Total Bandwidth Calculation Unit 102] The second total required bandwidth calculation unit 102 calculates the second total required bandwidth Wn for all terminals N (n=1 to N) having a modulation index kn lower than the modulation index kc of the first distribution format stream. Here, the second total required bandwidth calculation unit 102 calculates the second individual bandwidth (= b / log2kn) obtained by dividing the content bit rate b by the number of codeword bits based on the modulation index kn of the stream in the second distribution method, and then calculates the second total required bandwidth (= Σ i=1~n N Calculate bi / log2kni(t). Wn(t)=Σ i=1~n N bi / log2kni(t) kni: Deliver using the second delivery method stream at terminal i Content Modulation Index kni(t): modulation index at time period t log2kn(t): number of codeword bits in time period t

[0055] [Modulation index determination unit 103] The modulation index determination unit 103 determines the modulation index kc of the first distribution method stream, among multiple modulation indices kc in the first distribution method stream, such that the total required bandwidth W obtained by adding the first required bandwidth Wc and the second total required bandwidth Wn satisfies the specified bandwidth condition. W=Wc+Wn Here, as a predetermined band condition, for example, the modulation index kc is determined as follows. The modulation index kc that minimizes the total required bandwidth W The modulation index kc at which the total bandwidth W required is smaller than a predetermined threshold That is, the modulation index kc of the first distribution stream is determined so that W is the minimum or equal to or less than a predetermined threshold. This means that the first distribution stream is distributed most efficiently with the required total bandwidth W as small as possible.

[0056] In other words, the modulation index determination unit 103 determines the modulation index kc of the stream in the first distribution format in which the total required bandwidth W satisfies the predetermined bandwidth condition under the following circumstances. The lower the modulation index kc of the first distribution method stream, the smaller the number of codeword bits and the larger the first required bandwidth Wc. Conversely, the higher the modulation index kc of the first distribution method stream, the larger the number of codeword bits and the smaller the first required bandwidth Wc.

[0057] Furthermore, the modulation index determination unit 103 determines the modulation index kc of the stream in the first distribution format in which the total required bandwidth W satisfies the predetermined bandwidth condition under the following circumstances. The greater the number of channels m(t), the larger the first required bandwidth Wc. Conversely, the smaller the number of channels m(t), the smaller the first required bandwidth Wc.

[0058] Furthermore, the modulation index determination unit 103 determines the modulation index kc of the first distribution method stream in which the total required bandwidth W satisfies the predetermined bandwidth condition under the following circumstances. The greater the number of viewing households N, the larger the second total required bandwidth Wn. Conversely, the smaller the number of viewing households N, the smaller the second total required bandwidth Wn.

[0059] FIG. 5 is an explanatory diagram showing the relationship between the modulation index and the total bandwidth in the present invention.

[0060] The modulation index (MCS (Modulation and Coding Scheme)) is an index that combines the radio modulation method (modulation) and the error correction coding method (coding). 5G supports QPSK, 16QAM, 64QAM, 256QAM, and 1024QAM as modulation indices. 256QAM has the highest number of bits that can be transmitted per radio symbol (RE: Resource Element), but has low noise resistance. On the other hand, QPSK has a low number of bits that can be transmitted per telephone symbol, but has strong noise resistance. By encoding the transmitted data with redundant information, even if some transmission errors occur, the receiving side can correct the errors. The ratio of the amount of redundant information to the actual data amount (coding rate) determines the amount of transmittable data and error resistance.

[0061] According to Figure 5, it is expressed as follows: (MCS) (Modulation method) (Encoding rate) (Cover rate) (Required bandwidth Wc) 0 BPSK 1 / 2 Wide Large 1 QPSK 1 / 2 ↓ ↓ 2 QPSK 3 / 4 ↓ ↓ 3 16QAM 1 / 2 ↓ ↓ 4 16QAM 3 / 4 ↓ ↓ 5 64QAM 2 / 3 ↓ ↓ 6 64QAM 3 / 4 ↓ ↓ 7 64QAM 5 / 6 ↓ ↓ 8 256QA 3 / 4 ↓ ↓ 9 256QAM 5 / 6 ↓ ↓ 10 1024QAM 3 / 4 ↓ ↓ 11 1024QAM 5 / 6 Narrow Small

[0062] The first required bandwidth Wc and the second total required bandwidth Wn have the following relationship: When the first delivery method stream is broadcast with high communication quality, the first required bandwidth Wc becomes smaller and the coverage rate becomes narrower. On the other hand, the number of terminals using the second delivery method stream increases, which may increase the second total required bandwidth Wn. When the first delivery method stream is broadcast with low communication quality, the first required bandwidth Wc increases and the coverage rate increases. On the other hand, the number of terminals receiving the second delivery method stream also decreases, which may result in a smaller second total required bandwidth Wn. Then, a modulation index kc of the first distribution method stream is determined such that the total required bandwidth W obtained by adding the first required bandwidth Wc and the second total required bandwidth Wn is, for example, the minimum or equal to or less than a predetermined threshold. W=Wc+Wn

[0063] FIG. 6 is a sequence diagram of the entire system according to the present invention.

[0064] (S1) The terminal 4 transmits the user's desired "viewing channel" to the distribution device 1 via the base station 3. The base station 3 also notifies the distribution device 1 of the "modulation index" determined for each terminal 4. (S2) The distribution device 1 transmits to the content server 2 a content request including the viewing channel and a predetermined modulation index kc. (S3) In response to this, the content server 2 transmits content based on the modulation index kc of the viewing channel in response to the content request to the distribution device 1. The distribution device 1 distributes the content to multiple terminals 4 via the base station 3 using a first distribution method stream (broadcast or multicast). (S4) Now, suppose that terminal 4 detects a loss in the content of the viewing channel it is receiving via the first delivery method stream. In particular, terminal 4 with a modulation index lower than modulation index kc will experience a loss in the content of the first delivery method stream. (S5) At this time, the terminal 4 transmits a unicast distribution request corresponding to the missing channel to the distribution device 1 via the base station 3. (S6) In response to this, the distribution device 1 transmits to the content server 2 a content request according to the viewing channel and modulation index kn of the terminal 4 that transmitted the unicast distribution request. (S7) The content server 2 transmits the content of the viewing channel in response to the content request to the distribution device 1 at a bit rate of the modulation index kn. The distribution device 1 distributes the content to the terminal 4 via the base station 3 using the second distribution stream.

[0065] As described above in detail, the distribution device, program, and method of the present invention enable a distribution device to determine the optimal distribution stream for real-time broadcasting services when distributing content to a terminal via a base station. According to the present invention, for each base station, based on the modulation index kn determined for each terminal, the modulation index kc of the content to be distributed by broadcast or multicast is determined so that the total bandwidth W is minimized or kept below a predetermined threshold.

[0066] With respect to the various embodiments of the present invention described above, various changes, modifications, and omissions that fall within the scope of the technical spirit and aspects of the present invention may be easily made by those skilled in the art. The above description is merely illustrative and is not intended to be limiting in any way. The present invention is limited only by the claims and their equivalents. [Explanation of symbols]

[0067] 1. Distribution device 10 Distribution control section 100 Modulation index memory section 101 First required bandwidth calculation unit 102 Second total required bandwidth calculation unit 103 Modulation index determination unit 11 First Distribution Section 12 Second Distribution Section 2 Content Server 3 base station 4. Terminal

Claims

1. A distribution device that distributes content to a plurality of terminals via a base station using a plurality of distribution method streams, For each base station, a modulation index kn determined for each terminal is stored, For each base station, a first transmission method stream is transmitted to a terminal having a modulation index kn that is equal to or greater than a predetermined modulation index kc; For each base station, a second distribution method stream is distributed to a terminal having a modulation index kn lower than a predetermined modulation index kc. A distribution device characterized by:

2. a first required bandwidth calculation means for calculating a first required bandwidth Wc at a modulation index kc of a first distribution method stream; a second total required bandwidth calculation means for calculating a second total required bandwidth Wn for all terminals having a modulation index kn lower than the modulation index kc of the first distribution method stream; a modulation index determination means for determining a modulation index kc of a first delivery method stream, the modulation index kc being such that a total required bandwidth W obtained by adding the first required bandwidth Wc and the second total required bandwidth Wn satisfies a predetermined bandwidth condition, among a plurality of modulation indices kc of the first delivery method stream; 2. The distribution device according to claim 1, further comprising:

3. The modulation index determining means determines, as a predetermined band condition, a modulation index kc at which the required total band W is smallest, or a modulation index kc at which the required total band W is smaller than a predetermined threshold value.

3. The distribution device according to claim 2.

4. The first required bandwidth calculation means calculates a first required bandwidth Wc (=b / log 2 Calculate kc 3. The distribution device according to claim 2.

5. The modulation index determining means The lower the modulation index kc of the first distribution method stream, the smaller the number of codeword bits and the larger the first required bandwidth Wc. The higher the modulation index kc of the first distribution method stream, the larger the number of codeword bits and the smaller the first required bandwidth Wc. In the above, a modulation index kc of the first distribution method stream is determined so that the required total bandwidth W satisfies the predetermined bandwidth condition.

3. The distribution device according to claim 2.

6. The first required bandwidth calculation means calculates the first required bandwidth Wc (= m(t)·b / log 2 kc(t)) The modulation index determining means The greater the number of channels m(t), the larger the first required bandwidth Wc becomes. The smaller the number of channels m(t), the smaller the first required bandwidth Wc. In the above, a modulation index kc of the first distribution method stream is determined so that the required total bandwidth W satisfies the predetermined bandwidth condition.

6. The distribution device according to claim 5.

7. The second total required bandwidth calculation means calculates a second individual bandwidth (=b / log 2 kn), the second total required bandwidth (=Σ i=1～n N bi / log 2 kni(t)) The modulation index determining means The larger the number of viewing households n, the larger the second required total bandwidth Wn. The smaller the number of viewing households n, the smaller the second required total bandwidth Wn. In the first distribution method, a modulation index kc of the stream is determined so that the total required bandwidth W satisfies the predetermined bandwidth condition.

7. The distribution device according to claim 5 or 6.

8. The first delivery method stream is delivered by broadcast and the second delivery method stream is delivered by unicast, or The first distribution method stream is distributed by multicast, and the second distribution method stream is distributed by unicast, and also distributed by unicast to terminals that have not transmitted a multicast participation request.

3. The distribution device according to claim 1 or 2.

9. The distribution device is a core system device that functions as an MBS (Multi-Broadcast Service) and is connected between a content server that transmits content from multiple channels and a base station that distributes content to multiple terminals in a real-time broadcasting service.

3. The distribution device according to claim 1 or 2.

10. The core system device transmits a content request including the modulation index kc of the first delivery method stream determined by the modulation index determination means to the content server, and transmits each content request including each modulation index kn of the second delivery method stream to the content server; Receives content with a bit rate corresponding to each modulation index included in each content request from the content server and distributes it to the base station.

3. The distribution device according to claim 1 or 2.

11. A program that causes a computer installed in a device that distributes content to multiple terminals via a base station using multiple distribution method streams to function, For each base station, a modulation index kn determined for each terminal is stored, For each base station, a first transmission method stream is transmitted to a terminal having a modulation index kn that is equal to or greater than a predetermined modulation index kc; For each base station, a second distribution method stream is distributed to a terminal having a modulation index kn lower than a predetermined modulation index kc. A program that causes a computer to function in such a way.

12. A distribution method for a device that distributes content to multiple terminals via a base station using multiple distribution method streams, comprising: The device is For each base station, a modulation index kn determined for each terminal is stored, For each base station, a first transmission method stream is transmitted to a terminal having a modulation index kn that is equal to or greater than a predetermined modulation index kc; For each base station, a second distribution method stream is distributed to a terminal having a modulation index kn lower than a predetermined modulation index kc. The method for distributing a device is characterized by performing the following.

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