JP6195757B2 - Content distribution server and content distribution program - Google Patents

Description

The present invention, to deliver all at once the IP (Internet Protocol) content to a plurality of receiving apparatus, a content delivery server you and content distribution program.

  2. Description of the Related Art Conventionally, a push type information distribution technique is known in which information is directly sent from a distribution server to a user's receiving device without the user's voluntary action. Examples of distribution information (IP content) include information related to TV broadcast programs, the latest information on weather according to individual user needs, the latest information on traffic, applications, or various data requested by users.

  In a push type information distribution service linked to a TV broadcast program, information is distributed in real time as the program progresses in the receiving device. Such a service is particularly effective in increasing the added value of a television program.

  In a large-scale IP content push-type information distribution service, one content distribution server and each of a large number of receiving devices establish a communication session, and the content distribution server distributes IP content to each receiving device. Become. At that time, IP content distributed in real time is simultaneously distributed from the content distribution server to the receiving device.

  In such an IP content distribution system, a technique is known in which a distribution network is constructed so as to reduce the distribution delay time by taking into account the installation location of the receiving device, the connection environment, and the like (see Patent Document 1). ).

JP 2006-332825 A

  Distribution information linked to a TV broadcast program in IP content includes, for example, information on baseball players and soccer players displayed on the screen by broadcast waves in sports broadcast programs, quiz questions and answers linked to the program, and information Store information and product information displayed on the screen in the program, information (subtitles) according to the content of one scene of the drama and the characters spoken by the characters, and the like. It is desirable that these be distributed (synchronized) as much as possible to the screen of the TV broadcast program. For example, before the screen is displayed, related distribution information is displayed in advance, or a screen related to the distribution information has already been displayed. If the distribution information remains as it is even though the (scene) has ended, it is very uncomfortable for the viewer. Therefore, it is important to display the distribution information (IP content) as much as possible by linking with the screen of the TV broadcast program.

  However, the timing at which the IP content information is actually delivered to the receiving device by the content delivery server differs for each receiving device even in the case of simultaneous delivery. The reason for this is that when IP content is distributed simultaneously from one content distribution server to a large number of receiving devices, the server has only one communication interface (I / F) regardless of the number of receiving devices. This is because the distributed packets are multiplexed in time series (Time Division Multiplex (TDM)). Furthermore, even if each receiving apparatus that has established a session with the content distribution server is connected to the same (one) content distribution server, the communication position of the receiving apparatus (for example, the content distribution server is arranged in Tokyo). Depending on the situation, the time required for communication with the content distribution server differs depending on the receiving device depending on the location of the receiving device in Tokyo, Osaka, Okinawa, etc., that is, the round trip time (RTT) of information Are different). As a result, the timing at which the IP content actually reaches each receiving device varies.

  Note that the technique described in Patent Document 1 is to construct a distribution network by calculating a combination of a distribution server and a receiving device so that the distribution delay time becomes smaller for a plurality of distribution servers and each receiving device. However, the difference in delivery delay of each receiving device when connected to the same (one) content delivery server, which is a problem in the present invention, that is, the difference in arrival timing of IP content delivered to each receiving device Is not considered.

The present invention has been made in view of the above-described problems, and when distributing IP content from a content distribution server to a plurality of receiving devices all at once, variations in the arrival time of the distribution content in each receiving device are reduced. can be reduced, it is an object of the present invention to provide a content delivery server you and content delivery program.

To solve the previous SL problem, the content delivery server of claim 1, the plurality of receiving devices connected via the IP network, the content distribution server for distributing simultaneously the IP content to be displayed on the receiving device And it was set as the structure provided with the session control part, the delay amount measurement part, the delivery time determination part, and the content transmission part.

In such a configuration, the content distribution server receives connection requests from a plurality of receiving devices by the session control unit, and establishes a session with each of the plurality of receiving devices.
Then, the content distribution server transmits a delay amount confirmation request for confirming in advance the reception delay amount of the IP content from the content distribution server to the receiving device to the plurality of receiving devices that have established the session by the delay amount measuring unit. To do. Thereby, the content distribution server receives response information for the delay amount confirmation request from each of the receiving devices, and measures the reception delay amount of each of the plurality of receiving devices.

  Further, the content distribution server determines the distribution order of the IP contents in descending order of the measured reception delay amount by the distribution time determination unit, and matches the arrival time of the IP content of the receiving apparatus having the largest reception delay amount. Then, the distribution time to each receiving apparatus is calculated with the distribution time of the IP content to the receiving apparatus having the largest reception delay amount as a reference time, and distribution time information including the determined distribution order and the calculated distribution time is generated. . Then, the content distribution server stores the generated distribution time information in the storage unit.

  Also, the content distribution server transmits the IP content to each of the plurality of receiving devices at the calculated distribution time by the established session based on the distribution order determined by the content transmission unit.

  Thus, when the content distribution server distributes IP content to a plurality of receiving devices all at once, the IP content to other receiving devices is matched with the arrival time of the receiving device having the largest amount of IP content reception delay. Since the distribution is performed at an appropriate distribution time at the time of distribution, the arrival times of the IP contents can be matched in each receiving apparatus.

Further, the content distribution server, the storage unit, required time associated with the processing of the communication I / F required when one data delivery (L) is, is further stored, delivery time determining unit, In calculating the distribution time to each receiving device, the ideal distribution time (T _n ) to the n-th receiving device with the distribution order is calculated based on the following equation (1):
_{T n = t 1 + (RDT} 1 -RDT n) ... formula (1)
Furthermore, based on the following equation (2), the actual distribution time (t _n-1 ) of the IP content with the previous distribution order and the ideal distribution time (T _n ) of the IP content with the distribution order Determine whether the interval is longer than the required time (L),
_Tn <tn _-1 + L ... Formula (2)
When the expression (2) is not satisfied, the ideal distribution time (T _n ) is stored in the distribution time information as the actual distribution time (t _n ), and when the expression (2) is satisfied, the following Based on Expression (3), the time obtained by adding the required time (L) to the actual distribution time (t _n-1 ) of the IP content of the previous distribution order is set as the actual distribution time (t _n ). It memorize | stores in time information _tn = tn _-1 + L ... Formula (3)
It is characterized by.
Here, t ₁ is a group quasi-point in time, is a delivery time of I P content delivery order is Ru is delivered to the first. RDT _n is a reception delay amount of I P content delivery order is Ru are delivered to n-th. t _n, the distribution order is the actual delivery time of I P content to the n-th reception apparatus.

  As a result, the content distribution server performs actual distribution based on the reception delay amount of each reception device and the required time associated with the processing of the communication I / F so as to match the arrival time of the reception device having the largest reception delay amount. Time can be calculated. Therefore, the arrival time of the IP content can be more accurately matched in each receiving device.

In addition, the content distribution program according to claim 2 controls a computer serving as a content distribution server that simultaneously distributes IP content to be displayed on a plurality of receiving devices connected via an IP network. Means, delay amount measuring means, delivery time determining means, and content transmitting means.

In such a configuration, the content distribution program receives connection requests from a plurality of receiving devices by the session control means, and establishes a session with each of the plurality of receiving devices.
Then, the content distribution program transmits a delay amount confirmation request for confirming in advance the reception delay amount of the IP content to the receiving device by the delay amount measuring means to the plurality of receiving devices that have established sessions. Thereby, the delay amount measuring means of the content distribution program receives the response information for the delay amount confirmation request from each of the receiving devices, and measures the receiving delay amount of each of the plurality of receiving devices.

  In addition, the content distribution program determines the distribution order of the IP content in descending order of the measured reception delay amount by the distribution time determining means, and matches the arrival time of the IP content of the receiving device having the largest reception delay amount. Then, the distribution time to each receiving apparatus is calculated with the distribution time of the IP content to the receiving apparatus having the largest reception delay amount as a reference time, and distribution time information including the determined distribution order and the calculated distribution time is generated. . The content distribution program stores the generated distribution time information in the storage unit.

  In addition, the content distribution program transmits the IP content to each of the plurality of receiving devices by the established session at the calculated distribution time based on the distribution order determined by the content transmission unit.

Since this content distribution program causes the computer to function as each of the above-described means, when distributing IP content to a plurality of receiving devices all at once, it matches the arrival time of the receiving device with the largest amount of IP content reception delay. Since the distribution is performed at the optimal distribution time when distributing the IP content to other receiving apparatuses, the arrival times of the IP contents can be matched in each receiving apparatus.
The storage means further stores the required time (L) associated with the processing of the communication I / F required for one data distribution, and the distribution time determination means distributes to each receiving device. In calculating the time, an ideal distribution time (T _n ) to the receiving apparatus with the nth distribution order is calculated based on the following formula (1) :
_{T n = t 1 + (RDT} 1 -RDT n) ... formula (1)
Furthermore, based on the following equation (2), the actual distribution time (t _n-1 ) of the IP content with the previous distribution order and the ideal distribution time (T _n ) of the IP content with the distribution order Determine whether the interval is longer than the required time (L),
_{T n <t n-1 +} L ... formula (2)
When the expression (2) is not satisfied, the ideal distribution time (T _n ) is stored in the distribution time information as the actual distribution time (t _n ), and when the expression (2) is satisfied, the following Based on Expression (3), the time obtained by adding the required time (L) to the actual distribution time (t _n-1 ) of the IP content of the previous distribution order is set as the actual distribution time (t _n ). Memorize in time information
_{t n = t n-1 +} L ... formula (3)
It is characterized by.
Here, t ₁ is the reference point, a distribution time of the IP content delivery order is delivered to the first. RDT _n is the reception delay amount of the IP content distributed in the nth distribution order. t _n is the actual distribution time of the IP content to the receiving apparatus having the nth distribution order.
As a result, the content distribution program performs actual distribution based on the reception delay amount of each reception device and the required time associated with the processing of the communication I / F so as to match the arrival time of the reception device having the largest reception delay amount. Time can be calculated. Therefore, the arrival time of the IP content can be more accurately matched in each receiving device.

The present invention has the following excellent effects.
According to the invention described in 請 Motomeko 1 transmits When establishing a session to receive a connection request from the receiving apparatus connected via an IP network, the delay confirmation request to the respective receiving devices By receiving the response information, the reception delay amount for each receiving device can be measured. Furthermore, according to the present invention, IP content can be transmitted at a delivery time that matches the arrival time of the receiving device having the largest reception delay amount of the IP content in order from the receiving device having the largest measured reception delay amount. Therefore, the arrival times of the IP contents can be matched in each receiving apparatus.

In addition, the actual delivery time can be calculated based on the reception delay amount of each reception device and the required time associated with the processing of the communication I / F so as to match the arrival time of the reception device having the largest reception delay amount. it can. Therefore, the arrival time of the IP content can be more accurately matched in each receiving device.

It is a figure which shows the structural example of the content delivery system which concerns on the 1st Embodiment of this invention. It is a functional block diagram which shows the structural example of the content delivery server which concerns on the 1st Embodiment of this invention. It is a figure which shows the data structural example of the session management information which concerns on the 1st Embodiment of this invention. It is a figure which shows the data structural example of the delivery order information which concerns on the 1st Embodiment of this invention. It is a flowchart which shows operation | movement of the content delivery server which concerns on the 1st Embodiment of this invention. It is a figure which shows the structural example of the content delivery system which concerns on the 2nd Embodiment of this invention. It is a functional block diagram which shows the structural example of the content delivery server which concerns on the 2nd Embodiment of this invention. It is a figure which shows the data structural example of the session management information which concerns on the 2nd Embodiment of this invention. It is a figure which shows the data structural example of the delivery time information which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows operation | movement of the content delivery server which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows the flow of the process which calculates actual delivery time by the delivery time determination part of the content delivery server which concerns on the 2nd Embodiment of this invention.

  Hereinafter, modes for carrying out the present invention (hereinafter referred to as “embodiments”) will be described with reference to the drawings.

(First embodiment)
First, the content distribution system 5 according to the first embodiment of the present invention will be described.

<Outline of content distribution system 5>
First, the outline of the content distribution system 5 according to the first embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 1, a content distribution system 5 is connected to a content distribution server 1 and a plurality of receiving devices 3 (3a, 3b, 3c,..., 3n) via an IP network (IP network) 2. Configured. Then, the content distribution server 1 distributes IP content all at once to the receiving devices 3 (3a, 3b, 3c,..., 3n) via the IP network 2. The receiving device 3 is, for example, a PC (Personal Computer), a mobile phone, a smartphone, a television, and the like, and has at least a function of receiving and displaying a broadcast wave and a function of transmitting and receiving information connected to the IP network 2. The IP content (distribution information) received from the content distribution server 1 is displayed on the screen together with the broadcast wave received in real time.

This content distribution server 1 multiplexes and transmits IP content to be distributed (specifically, packets transmitted via the IP network 2) in time series. Furthermore, since the communication positions (installation locations) of the receiving devices 3 (3a, 3b, 3c,..., 3n) that receive the IP content are different from each other, the content distribution server 1 and the receiving devices 3 (3a, 3b, 3c,. 3n) The amount of reception delay with each other (for example, a value obtained by halving the round-trip delay time (RTT)) is different from each other, such as A second, B second, C second,. (See FIG. 1).
Therefore, the arrival time of the IP content simultaneously distributed from the content distribution server 1 to each receiving device 3 (3a, 3b, 3c,..., 3n) is the receiving device 3 (3a, 3b, 3c,..., 3n). In this case, variations occur.

Therefore, when the content distribution server 1 according to the first embodiment of the present invention receives a connection request from each receiving device 3 connected via the IP network 2 and establishes a session, Send a delay confirmation request. Then, the content distribution server 1 receives the response information for the delay amount confirmation request from each receiving device 3, so that the reception delay amount for each receiving device 3 (for example, a value obtained by halving the round trip delay time (RTT)). ). Based on the measurement result, the content distribution server 1 determines the IP content distribution order in order from the receiving device 3 with the largest reception delay amount, and executes the distribution of the IP content according to the determined distribution order.
In this way, in the content distribution system 5 according to the embodiment of the present invention, when the IP content is simultaneously distributed from the content distribution server 1 to each receiving device 3, the distribution content in each receiving device 3 is distributed. The variation in arrival time can be reduced.

<Configuration of Content Distribution Server 1>
Next, the configuration of the content distribution server 1 according to the first embodiment of the present invention will be described with reference to FIG. 2 (refer to FIG. 1 as appropriate).
FIG. 2 is a functional block diagram showing a configuration example of the content distribution server 1 according to the first embodiment of the present invention. The content distribution server 1 is a device that distributes IP content to a plurality of receiving devices 3 via the IP network 2, and includes a control unit 10, a communication unit 20, an input / output unit (not shown), and a storage unit 30. Consists of including.

  The communication unit 20 is configured by a communication interface that receives a connection request or the like from the receiving device 3 or transmits a delay amount confirmation request to the receiving device 3 via the IP network 2. The input / output unit (not shown) is configured by an input / output interface for inputting / outputting information to / from an input unit such as a keyboard or an output unit such as a monitor, which is not shown.

  The control unit 10 controls the entire content distribution server 1 and includes a session control unit 11, a delay amount measurement unit 12, a content generation unit 13, a distribution order determination unit 14, and a content transmission unit 15.

  The session control unit (session control means) 11 receives a connection request or a disconnection request from the receiving device 3 and controls establishment or disconnection of a session with the receiving device 3. Further, the session control unit 11 assigns a session ID to the session at the time of establishment of the session, and adds a record regarding the session to the session management information 100 (see FIG. 3) in the storage unit 30 to be described later. Information related to the session linked to the session ID is stored.

The delay amount measuring unit (delay amount measuring unit) 12 measures the reception delay amount of each receiving device 3 and stores it in the session management information 100 (see FIG. 3) in the storage unit 30.
The delay amount measuring unit 12 measures a reception delay amount by transmitting a delay amount confirmation request to each receiving device 3. This delay amount confirmation request is transmitted in order to confirm in advance the reception delay amount of the IP content from the content distribution server 1 to the receiving device 3.
Specifically, the delay amount measurement unit 12 executes request information (echo request) indicating that a response is returned to each receiving device 3 by executing a ping command of ICMP (Internet Control Message Protocol), for example. Is transmitted to each receiving device 3, response information (echo response) is received from each receiving device 3, and the time when request information (echo request) is transmitted and the time when response information (echo response) is received To measure the round trip delay time (RTT). Then, the delay amount measuring unit 12 calculates the reception delay amount by halving the measured round trip delay time (RTT). In addition, when the transmission / reception between the content distribution server 1 and the receiving device 3 is performed by TCP (Transmission Control Protocol), the delay amount measurement unit 12 receives a request message (delay amount confirmation request) from the content distribution server 1. The round trip delay time (RTT) may be measured based on the difference between the time when the ACK message is received from the receiving device 3 and the request message is transmitted and the time when the ACK message is received.

FIG. 3 is a diagram illustrating a data configuration example of the session management information 100 according to the first embodiment of the present invention.
As shown in FIG. 3, the session management information 100 includes session information 102 and reception delay amount 103 information for each session ID 101.

In the session ID 101, an identifier unique to the session established with the receiving device 3 is added and stored by the session control unit 11. For example, “ID0” or the like is stored as the session ID 101.
In the session information 102, the session control section 11 stores the session information of the session assigned with the session ID 101, specifically, the IP address and port number of the receiving device 3. In FIG. 3, for example, session information regarding a session whose session ID 101 is “ID0” is expressed as “session 0”, and session information regarding a session whose session ID 101 is “ID1” is expressed as “session 1” or the like. Yes.
In the reception delay amount 103, the delay amount measurement unit 12 stores the reception delay amount between the content distribution server 1 and the reception device 3 that has established the session indicated by the session ID 101. FIG. 3 shows an example in which a value obtained by halving the round trip time (RTT) is stored as the reception delay amount 103. In addition, since the reception delay amount 103 in the first embodiment is information used by the distribution order determination unit 14 to determine the distribution order, the round trip time (RTT) is not halved and the round trip time is reduced. The value of the delay time (RTT) itself may be regarded as the reception delay amount 103 and stored in the session management information 100.

  A record for each session ID 101 included in the session management information 100 is generated when a session is established with the receiving device 3 by the session control unit 11. Further, when the session control unit 11 disconnects the session, the session control unit 11 deletes the record associated with the session ID 101 of the session from the session management information 100 stored in the storage unit 30.

  Returning to FIG. 2, the content generation unit 13 generates IP content to be distributed to each receiving device 3. The content generation unit 13 is not provided in the content distribution server 1, but is provided in another device provided outside, and the content distribution server 1 transmits the IP content generated by the other device to the communication unit 20 or It may be acquired via an input / output unit (not shown) and stored in the storage unit 30.

  The distribution order determining unit (distribution order determining means) 14 refers to the session management information 100 (FIG. 3) in the storage unit 30, and in descending order of the reception delay amount 103 stored as the session management information 100, that is, round trip. The records associated with the session ID 101 are sorted in the descending order of the value obtained by halving the delay time (RTT) to determine the distribution rank, and the distribution rank information 150 (see FIG. 4) is generated.

FIG. 4 is a diagram illustrating a data configuration example of the distribution order information 150 according to the first embodiment of the present invention. As shown in FIG. 4, the distribution order information 150 is information in which the distribution order 151 is determined by sorting the records in descending order of the reception delay amount 103 of the session management information 100 of FIG. In FIG. 4, the receiving apparatus 3 connected in the session with the session ID 101 “ID2” is “1” having the highest distribution order 151, and the receiving apparatus 3 connected in the session with the session ID 101 “ID1” is distributed. The rank 151 is “2”, which is the next highest rank, and the distribution rank 151 of the receiving apparatus 3 connected in the session with the session ID 101 “ID0” is “3”, which is the next rank. .
When the session control unit 11 disconnects the session, the session control unit 11 deletes the record associated with the session ID 101 of the session from the distribution order information 150. At that time, the delivery order determination unit 14 determines and updates the delivery order 151 in descending order of the reception delay amount 103 except for the deleted record.

  Returning to FIG. 2, the content transmission unit (content transmission unit) 15 refers to the distribution order information 150 stored in the storage unit 30 and based on the distribution order 151 determined by the distribution order determination unit 14, that is, the reception delay. The IP contents are transmitted to the corresponding session in the descending order of the amount 103, and transmitted to the receiving device 3.

  The storage unit (storage unit) 30 includes storage units such as a hard disk, a flash memory, and a RAM (Random Access Memory), and stores the session management information 100, the distribution order information 150, and the like.

  The control unit 10 is realized by, for example, a program (content distribution program) stored in the storage unit 30 being developed and executed in a RAM which is a main memory by a CPU (Central Processing Unit) (not shown). The

  As described above, the content distribution server 1 can determine the IP content distribution order in order from the receiving device 3 having the largest reception delay amount, and can transmit the IP content according to the determined distribution order. Therefore, when the IP content is simultaneously distributed from the content distribution server 1 to each receiving device 3, it is possible to reduce variations in the arrival time of the distribution content in each receiving device 3.

<Operation of Content Distribution Server 1>
Next, the operation of the content distribution server 1 according to the first embodiment of the present invention will be described with reference to FIG. 5 (refer to FIGS. 1 to 4 as appropriate).
FIG. 5 is a flowchart showing the operation of the content distribution server 1 according to the first embodiment of the present invention. Here, the delay amount measuring unit 12 of the content distribution server 1 measures the round trip delay time (RTT) by executing the ping command, and halves the measured round trip delay time (RTT). Thus, description will be made assuming that the reception delay amount is calculated.

  First, the session control unit 11 of the content distribution server 1 receives a connection request from each receiving device 3 (step S10).

  Then, the session control unit 11 establishes a session with the receiving device 3, assigns a session ID to each established session, and adds a new record to the session management information 100 (see FIG. 3) in the storage unit 30. create. The session control unit 11 stores the session information between the session ID and the receiving device 3 associated with the session ID in the created record (step S11).

  Subsequently, the delay amount measuring unit 12 transmits a delay amount confirmation request to each receiving device 3 (step S12). Specifically, the delay amount measurement unit 12 transmits request information (echo request) for returning a response to each receiving device 3 to each receiving device 3 by executing a ping command.

  Then, the delay amount measuring unit 12 receives the response information (echo response) from each receiving device 3, and the difference between the time when the request information (echo request) is transmitted and the time when the response information (echo response) is received To measure the round trip delay time (RTT). The delay amount measuring unit 12 stores a value obtained by halving the measured round trip delay time (RTT) with each receiving device 3 in the session management information 100 as a reception delay amount (step S13).

  Next, the distribution order determination unit 14 refers to the session management information 100 (FIG. 3) in the storage unit 30 and determines the reception delay amount 103 stored in the session management information 100 in descending order, that is, the round trip delay time ( The records associated with the session IDs are sorted in descending order of the value obtained by halving (RTT) to determine the distribution rank, and distribution rank information 150 (see FIG. 4) is generated (step S14).

  Then, the content transmission unit 15 acquires the information on the IP content generated by the content generation unit 13, refers to the distribution order information 150 (FIG. 4), and receives the IP content from the one with the highest distribution order. (Step S15).

  Subsequently, the session control unit 11 determines whether or not the distribution of the IP content has ended (step S16). If the distribution has not ended (step S16 → No), the session control unit 11 returns to step S12 and continues the processing. On the other hand, when the distribution is finished (step S16 → Yes), the process proceeds to the next step S17.

In step S <b> 17, the session control unit 11 receives a session disconnection request from the receiving device 3.
Subsequently, the session control unit 11 deletes the record related to the session in the session management information 100 (see FIG. 3) and the distribution order information 150 (see FIG. 4) in the storage unit 30 for the session that has received the disconnection request (see FIG. 4). Step S18), the process ends.

Note that the processing from the transmission of the delay amount confirmation request to each receiving device 3 to the generation of the distribution order information 150 executed in steps S12 to S14 is always executed immediately after the session with the receiving device 3 is established. In the loop after transmission of the IP content in S15 (in the case of step S16 → No), it is not always necessary to execute it every time, and may be executed at a predetermined timing. In that case, the transmission of the IP content to each receiving device 3 by the content transmitting unit 15 in step S15 is executed in the order based on the distribution order information 150 similar to the previous time stored in the storage unit 30.
If the session control unit 11 receives a disconnection request from the receiving device 3 after establishing a session with the receiving device 3 in step S11, the session control unit 11 does not finish the distribution of the IP content (step S16 → No). Even if the distribution is still in progress). And the session control part 11 deletes the record regarding the said session of the session management information 100 (refer FIG. 3) and the delivery order information 150 (refer FIG. 4) in the memory | storage part 30 about the session which received the cutting | disconnection request | requirement. In this way, the content distribution server 1 can update the distribution order information 150 with information about the session connected at that time.
Further, in step S14, the distribution order determination unit 14 refers to the session management information 100 (FIG. 3) in the storage unit 30 and halves the number of sessions and the reception delay amount 103 (round trip delay time (RTT)). Value) does not change compared to the previous generation of the distribution order information 150, the new distribution order information 150 is not created, that is, step S14 is not executed and stored in the storage unit 30. Based on the distribution order information 150, the processing after step S15 may be executed.

(Second Embodiment)
Next, a content distribution system 5a and the like according to the second embodiment of the present invention will be described.

<Outline of Content Distribution System 5a>
FIG. 6 is a diagram showing a configuration example of a content distribution system 5a according to the second embodiment of the present invention. The difference from the content distribution system 5 according to the first embodiment shown in FIG. 1 is that the content distribution server 1 according to the first embodiment is a content distribution server 1a as shown in FIG. It is. About the other structure, the code | symbol and name same as the structure shown in FIG. 1 are attached | subjected, and description is abbreviate | omitted.

In the content distribution system 5 according to the first embodiment, the content distribution server 1 receives a connection request from each receiving device 3 (3a, 3b, 3c,..., 3n) connected via the IP network. When a session is established, a delay amount confirmation request is transmitted to each receiving device 3 (3a, 3b, 3c,..., 3n), and the response information is received, whereby a receiving delay amount for each receiving device 3 (for example, , A value obtained by halving the round trip delay time (RTT). And the content delivery server 1 shall deliver IP content in an order from the receiver 3 with the largest received delay amount.
On the other hand, in the content distribution system 5a according to the second embodiment, the content distribution server 1a receives the reception delay amount (for example, round-trip delay time (RTT)) of each receiving device 3 as in the first embodiment. ) Is measured. Then, the content distribution server 1a identifies the receiving device 3 having the largest reception delay amount, and sets the distribution time of the IP content of each of the other receiving devices 3 so as to match the arrival time of the data of the identified receiving device 3. The IP content is calculated and distributed at the calculated distribution time.
By doing in this way, since the IP content for each of the other receiving devices 3 is distributed at an appropriate distribution time so as to match the arrival time of the receiving device 3 with the largest reception delay amount of the IP content, each receiving device The arrival times of the three IP contents can be matched. The “arrival time coincidence” in the second embodiment of the present invention is not a complete coincidence of the arrival times, but is an arrival time of the IP content distributed to each receiving device 3 as compared to the first embodiment. This means that the variation can be further reduced (details will be described later).

<Configuration of Content Distribution Server 1a>
Next, the configuration of the content distribution server 1a according to the second embodiment of the present invention will be described with reference to FIG. 7 (refer to FIG. 6 as appropriate).
FIG. 7 is a functional block diagram showing a configuration example of the content distribution server 1a according to the second embodiment of the present invention. The content distribution server 1a is a device that distributes IP content to a plurality of receiving devices 3 via the IP network 2, and includes a control unit 10, a communication unit 20, an input / output unit (not shown), and a storage unit 30. Consists of including.
The difference from the content distribution server 1 according to the first embodiment shown in FIG. 2 is that, as shown in FIG. 7, the content distribution server 2 according to the second embodiment includes a distribution in the control unit 10. In other words, the distribution time determination unit 16 is provided instead of the rank determination unit 14, and the content transmission unit 15 is the content transmission unit 15a. Furthermore, the storage unit 30 includes distribution time information 200 (see FIG. 9 described later) instead of the distribution order information 150 (see FIG. 2). In addition, about a structure other than that, it is provided with the function similar to the structure shown in FIG. 2, attaches | subjects the same code | symbol and a name, and abbreviate | omits description.

  The distribution time determination unit (distribution time determination means) 16 refers to the session management information 100 (FIG. 8 to be described later) stored in the storage unit 30 and arrives at the IP content arrival time of the receiving device 3 having the largest reception delay amount 103. The distribution order and the distribution time are calculated for each session of each session ID so that the distribution time information 200 (see FIG. 9) is generated.

  FIG. 9 is a diagram illustrating a data configuration example of the distribution time information 200 according to the second embodiment of the present invention. The distribution time information 200 shown in FIG. 9 is an example generated by the distribution time determination unit 16 based on the session management information 100 according to the second embodiment of the present invention shown in FIG.

  As shown in FIG. 9, the delivery time information 200 includes data of a delivery order 201, a session ID 101, session information 102, and a delivery time 202.

For the distribution order 201, the distribution time determination unit 16 refers to the session management information 100 (FIG. 8) in the storage unit 30, sorts the records associated with the session ID 101 in descending order of the reception delay amount 103, and determines the distribution order. Information.
In FIG. 9, the session management information 100 (FIG. 8) has the reception delay amount 103 of “50.0 ms”, and the session with the largest reception delay amount 103 is the session ID 101 connected by the session of “ID2”. The distribution order 201 of the receiving device 3 is “1”. Then, the distribution order 201 of the receiving apparatus 3 connected in the session with the session ID 101 of “ID3” having the next largest reception delay amount “40.0 ms” is “2”. Subsequently, the distribution order 201 of the receiving apparatus 3 connected in the session with the session ID 101 “ID1” having the next largest reception delay amount “38.0 ms” is “3”, and the reception delay amount 103 is This shows that the distribution order 201 of the receiving apparatus 3 connected in the session having the next largest ID “20.0 ms” and the session ID 101 “ID0” is “4”. The content transmitting unit 15a transmits IP content to each receiving device 3 in the order determined by the distribution order 201.

  In the session ID 101 and the session information 102, information of the session management information 100 (see FIG. 8) is stored in association with the distribution order 201.

In the distribution time 202, the distribution order 201 is “1”, that is, the IP content distribution time to the receiving device 3 having the largest reception delay amount 103 (see FIG. 8) (hereinafter, “t ₁ ” may be described). The distribution time 202 in the session of each distribution order 201 is stored in the case where “there is a reference time”.
The distribution time 202 is calculated by the distribution time determination unit 16 as follows.

The distribution time “t ₁ ” of the IP content distributed in the distribution order 201 “1” is set as the reference time point as described above. Then, the distribution time determination unit 16 obtains (ideal) time “T _n ” at which the “n” -th IP content in the distribution order 201 is distributed by the following equation (1). Here, the reception delay amount 103 (see FIG. 8) is the largest, the reception delay amount 103 of the IP content distributed in the distribution order 201 “1” is “RDT ₁ ”, and the distribution order 201 is “n”. The reception delay amount 103 of the delivered IP content is “RDT _n ”.

_{T n = t 1 + (RDT} 1 - RDT n) ... formula (1)

  For example, the distribution time 202 of the receiving device 3 whose distribution order 201 of the distribution time information 200 illustrated in FIG. 9 is “1” is calculated as follows using Expression (1).

T ₁ = t ₁ + (RDT ₁ −RDT ₁ )
= T ₁ + (50.0-50.0) = t ₁ + 0.0 (ms)

  Similarly, the distribution time 202 of the receiving device 3 whose distribution order 201 of the distribution time information 200 is “2” is calculated as follows using Expression (1).

T ₂ = t ₁ + (RDT ₁ −RDT ₂ )
= T ₁ + (50.0-40.0) = t ₁ + 10.0 (ms)

  Similarly, the distribution time 202 of the receiving device 3 whose distribution order 201 of the distribution time information 200 is “3” is calculated as follows using Expression (1).

T ₃ = t ₁ + (RDT ₁ −RDT ₃ )
= T ₁ + (50.0-38.0) = t ₁ + 12.0 (ms)

  Similarly, the distribution time 202 of the receiving device 3 whose distribution order 201 of the distribution time information 200 is “4” is calculated by the following formula (1).

T ₄ = t ₁ + (RDT ₁ −RDT ₄ )
= T ₁ + (50.0-20.0) = t ₁ + 30.0 (ms)

As described above, the distribution time determination unit 16 calculates the (ideal) distribution time associated with each distribution order 201 using the equation (1) by referring to the reception delay amount 103 of the session management information 100. To do. However, at this calculated (ideal) distribution time, there are cases where distribution cannot be performed for the following reason.
In normal content distribution, a plurality of receiving devices 3 are connected to one distribution server (one communication I / F), so packets that are actually distributed are multiplexed in time series (time division multiplexing). Is done. Therefore, a minimum required time, that is, a delay (time) associated with the distribution data size and communication I / F is essential for data distribution to each receiving device 3. Therefore, for example, when the required time “L” accompanying the communication I / F required for one data transmission is “0.5 ms”, when one IP content is distributed, “0” which is less than “0.5 ms” The next IP content cannot be delivered at an interval of .3 ms, and is always delivered after the required time “L” associated with the communication I / F of “0.5 ms”.

Therefore, the distribution time determination unit 16 ideally sets t _n = T, _where “t _n ” is the time at which distribution is actually performed to the n-th receiving device 3 (actual distribution time). _n , in consideration of the time required for delivery per receiving device 3 based on the delivery data size and the delay associated with the communication I / F “L”,
_Tn <tn _-1 + L ... Formula (2)
If the condition is satisfied, the distribution interval is less than “L”, which is the minimum distribution interval of the distribution server, so t _n is calculated by the following equation (3).

_{t n = t n-1 +} L ... formula (3)

That is, when T _n <t _n−1 + L, the distribution is performed later than the ideal time for distribution.

In this way, the distribution time determination unit 16 first calculates the (ideal) time “T _n ” for distributing the IP content using Expression (1). Next, the delivery time determination unit 16 determines whether or not Expression (2) is satisfied based on the calculated (ideal) time “T _n ”, and when Expression (2) is not satisfied, The ideal time “T _n ” is stored in the distribution time 202 of the distribution time information 200 as the actual distribution time “t _n ”. On the other hand, when the expression (2) is satisfied, the distribution time determination unit 16 calculates the actual distribution time “t _n ” according to the expression (3) and stores it in the distribution time 202 of the distribution time information 200.

The distribution time determination unit 16 determines the distribution order 201 of each session as described above, calculates the distribution time 202, generates the distribution time information 200 (see FIG. 9), and stores it in the storage unit 30. To do.
As described above, the IP content cannot be distributed at the (ideal) time “T _n ”, and the actual distribution is accompanied by the required time “L” accompanying the communication I / F required for one data transmission. Since the time “t _n ” may be delivered with a delay, the arrival time of the IP content to each receiving device 3 may not be completely coincident. However, as compared with the first embodiment, it is possible to further reduce variations in arrival times of IP contents distributed to each receiving device 3.

  Returning to FIG. 7, the content transmission unit (content transmission unit) 15 a refers to the distribution time information 200 (FIG. 9) stored in the storage unit 30, the distribution order 201 determined by the distribution time determination unit 16, that is, The IP content is transmitted to the corresponding session at the time indicated by the delivery time 202 in the descending order of the reception delay amount 103 (see FIG. 8), and is transmitted to the receiving device 3.

  As described above, the content distribution server 1a calculates the IP content distribution time to each of the other receiving devices 3 so as to match the arrival time of the receiving device having the largest IP content reception delay amount. The IP content can be distributed at the distributed time. Therefore, the arrival times of the IP contents can be matched in each receiving device 3. That is, the variation in the arrival time of the IP content can be further reduced.

<Operation of Content Distribution Server 1a>
Next, the operation of the content distribution server 1a according to the second embodiment of the present invention will be described with reference to FIG. 10 (refer to FIGS. 6 to 9 as appropriate).
FIG. 10 is a flowchart showing the operation of the content distribution server 1a according to the second embodiment of the present invention. Here, the delay amount measuring unit 12 of the content distribution server 1a measures the round trip delay time (RTT) by executing the ping command, and halves the measured round trip delay time (RTT). Thus, description will be made assuming that the reception delay amount is calculated. Further, it is assumed that the required time “L” (for example, “0.5 ms”) associated with the communication I / F is stored in advance in the storage unit 30 of the content distribution server 1a.

  First, the session control unit 11 of the content distribution server 1a receives a connection request from each receiving device 3 (step S20).

  Then, the session control unit 11 establishes a session with the receiving device 3, assigns a session ID to each established session, and adds a new record to the session management information 100 (see FIG. 8) in the storage unit 30. create. The session control unit 11 stores the session information between the session ID and the receiving device 3 associated with the session ID in the created record (step S21).

  Subsequently, the delay amount measuring unit 12 transmits a delay amount confirmation request to each receiving device 3 (step S22). Specifically, the delay amount measurement unit 12 transmits request information (echo request) for returning a response to each receiving device 3 to each receiving device 3 by executing a ping command.

Then, the delay amount measuring unit 12 receives the response information (echo response) from each receiving device 3, and the difference between the time when the request information (echo request) is transmitted and the time when the response information (echo response) is received To measure the round trip delay time (RTT). The delay amount measuring unit 12 stores a value obtained by halving the measured round-trip delay time (RTT) with each receiving device 3 in the session management information 100 as a reception delay amount (step S23).
In addition, the process to step S20-S23 so far is the same process as the process to step S10-S13 of FIG.

  Next, the distribution time determination unit 16 refers to the session management information 100 (FIG. 8) in the storage unit 30 and calculates a distribution rank 201 and a distribution time 202 for each receiving device 3 corresponding to each session ID. Distribution time information 200 (see FIG. 9) is generated (step S24).

Specifically, the delivery time determination unit 16 refers to the session management information 100 (FIG. 8), and determines the reception delay amount 103 stored in the session management information 100 in descending order, that is, the round trip delay time (RTT). The distribution rank 201 is determined by sorting the records associated with the session IDs in descending order of the halved value. Then, the distribution time determination unit 16 calculates (ideal) time “T _n ” for distributing the IP content using the above-described equation (1). Furthermore, the delivery time determination unit 16 uses the above-described equation (1) based on the required time “L” associated with the communication I / F stored in the storage unit 30 to obtain the (ideal) time “ It is determined whether or not the distribution can be performed by “T _n ” based on the equation (2), and when the distribution cannot be performed at the (ideal) time “T _n ”, the actual distribution time “ The distribution time information 200 is generated by calculating “t _n ”.

FIG. 11 is a flowchart showing a flow of calculating the actual delivery time “t _n ”.
The distribution time determination unit 16 determines whether or not the IP content can be distributed at the (ideal) time “T _n ” calculated using the equation (1), and the actual IP content in the previous distribution order 201 is determined. With reference to the delivery time “t _n−1 ” and the required time “L” associated with the communication I / F stored in the storage unit 30, the determination is made based on the above equation (2) (step S 30).

And the delivery time determination part 16 progresses to step S31, when satisfy | filling Formula (2) (step S30-> Yes).
In step S31, since the distribution time is less than the required time “L” associated with the communication I / F, the distribution time determination unit 16 determines the IP content in the previous distribution order 201 based on the above equation (3). The time obtained by adding the required time “L” to the actual distribution time “t _n−1 ” is defined as the actual distribution time “t _n ” of the IP content in the distribution order 201 (n-th).

On the other hand, the distribution time determination unit 16 proceeds to step S32 when the expression (2) is not satisfied (step S30 → No).
In step S32, the delivery time determination unit 16 sets the (ideal) time “T _n ” as the actual delivery time “t _n ” because the delivery interval is equal to or longer than the required time “L” associated with the communication I / F. (T _n = T _n ).

  In this way, the distribution time determination unit 16 calculates the distribution time 202 for each distribution order 201 and generates the distribution time information 200 (FIG. 9).

  Returning to FIG. 10, the content transmission unit 15 acquires the information on the IP content generated by the content generation unit 13, refers to the distribution time information 200 (FIG. 9), and starts with the distribution time 202 from the one having the highest distribution order 201. The IP content is transmitted to the receiving device 3 at the time indicated by (Step S25).

  Subsequently, the session control unit 11 determines whether or not the distribution of the IP content has ended (step S26). If the distribution has not ended (step S26 → No), the process returns to step S22 and continues the processing. On the other hand, when the distribution is finished (step S26 → Yes), the process proceeds to the next step S27.

In step S <b> 27, the session control unit 11 receives a session disconnection request from the receiving device 3.
Subsequently, the session control unit 11 deletes the record regarding the session in the session management information 100 (see FIG. 8) and the distribution time information 200 (see FIG. 9) in the storage unit 30 for the session that has received the disconnection request (see FIG. 9). Step S28), the process ends.

Note that the processing from the transmission of the delay amount confirmation request to each receiving device 3 to the generation of the distribution time information 200 executed in steps S22 to S24 is always executed immediately after the session with the receiving device 3 is established. In the loop after the transmission of the IP content in S25 (in the case of step S26 → No), it is not necessarily executed every time, and may be executed at a predetermined timing. In that case, the transmission of the IP content to each receiving device 3 by the content transmission unit 15 in step S25 is executed by the distribution order 201 and the distribution time 202 based on the distribution time information 200 similar to the previous time stored in the storage unit 30. The
If the session control unit 11 receives a disconnection request from the receiving device 3 after establishing a session with the receiving device 3 in step S21, the session control unit 11 does not finish IP content distribution (step S26 → No). Even if the distribution is still in progress). And the session control part 11 deletes the record regarding the said session of the session management information 100 (refer FIG. 8) and the delivery time information 200 (refer FIG. 9) in the memory | storage part 30 about the session which received the cutting | disconnection request | requirement. When the session control unit 11 deletes the record of the distribution time information 200, the distribution time determination unit 16 refers to the session management information 100 after deletion of the corresponding record and newly generates the distribution time information 200. Update. By doing in this way, the content delivery server 1a can update the delivery time information 200 to the information about the session connected at that time.
Further, in step S24, the delivery time determination unit 16 refers to the session management information 100 (FIG. 8) in the storage unit 30, and halves the number of sessions and the reception delay amount 103 (round trip delay time (RTT)). Value) does not change compared to the previous generation of the delivery time information 200, the new delivery time information 200 is not created, that is, step S24 is not executed and stored in the storage unit 30. Based on the distribution time information 200, the processing after step S25 may be executed.

As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment described here.
For example, the delay amount measuring unit 12 of the content distribution servers 1 and 1a measures the round-trip delay time (RTT) with each receiving device 3, and halves the measured round-trip delay time (RTT). The reception delay amount is calculated according to the above, but each receiving device 3 is provided with a timing unit that synchronizes the time, measures the reception time of the delay amount confirmation request received from the content distribution server 1, and receives the reception time. May be returned from each of the receiving apparatuses 3 to the content distribution servers 1 and 1a. That is, instead of the round trip delay time (RTT), the reception delay amount may be determined by measuring the delay time in one direction.

DESCRIPTION OF SYMBOLS 1,1a Content delivery server 2 IP network 3 Receiving device 5,5a Content delivery system 10 Control part 11 Session control part (session control means)
12 Delay measurement unit (delay measurement unit)
13 Content Generation Unit 14 Distribution Order Determination Unit (Distribution Order Determination Unit)
15, 15a Content transmission unit (content transmission means)
16 Distribution time determination unit (distribution time determination means)
20 communication unit 30 storage unit (storage unit)
100 Session management information 150 Delivery order information 200 Delivery time information

Claims (2)

A content distribution server that simultaneously distributes IP content to be displayed on a plurality of receiving devices connected via an IP network,
A session control unit that receives connection requests from a plurality of receiving devices and establishes a session with each of the plurality of receiving devices;
A delay amount confirmation request for confirming in advance the reception delay amount of the IP content from the content distribution server to the receiving device is transmitted to the plurality of receiving devices that have established the session, and each of the receiving devices receives the delay amount confirmation request. A delay amount measuring unit that measures the reception delay amount of each of the plurality of receiving devices by receiving response information to a delay amount confirmation request;
The receiving apparatus having the largest reception delay amount so as to match the arrival time of the IP content of the receiving apparatus having the largest reception delay amount while determining the distribution order of the IP contents in the descending order of the measured reception delay amount. The distribution time to each of the receiving devices is calculated based on the distribution time of the IP content to the reference time, and distribution time information including the determined distribution order and the calculated distribution time is generated and stored in the storage unit A delivery time determination unit,
A content transmission unit configured to transmit the IP content to each of the plurality of receiving devices based on the determined distribution order at the calculated distribution time through the established session;
Equipped with a,
The storage unit further stores a required time (L) associated with communication I / F processing required for one data distribution,
In the calculation of the delivery time to each of the receiving devices, the delivery time determination unit,
Based on the following formula (1), an ideal delivery time (T _n ) to the receiving device whose delivery order is nth is calculated,
_{T n = t 1 + (RDT} 1 -RDT n) ... formula (1)
Furthermore, based on the following formula (2), the actual distribution time (t _n-1 ) of the IP content with the previous distribution order and the ideal distribution time (T _n ) of the IP content with the distribution order Whether or not there is more than the required time (L),
_{T n <t n-1 +} L ... formula (2)
When the expression (2) is not satisfied, the ideal delivery time (T _n ) is stored as the actual delivery time (t _n ) in the delivery time information,
When the expression (2) is satisfied, based on the following expression (3), a time obtained by adding the required time (L) to the actual distribution time (t _n-1 ) of the IP content of the previous distribution order Is stored in the distribution time information as the actual distribution time (t _n )
_{t n = t n-1 +} L ... formula (3)
Content distribution server according to claim.

Here, t ₁ is the said reference point, a distribution time of the IP content delivery order is delivered to the first. RDT _n is the reception delay amount of the IP content distributed in the nth distribution order. t _n is the actual distribution time of the IP content to the receiving apparatus of the nth distribution order. A computer serving as a content distribution server for simultaneously distributing IP content to be displayed on the receiving device to a plurality of receiving devices connected via an IP network,
Session control means for receiving connection requests from a plurality of receiving devices and establishing a session with each of the plurality of receiving devices;
A delay amount confirmation request for confirming in advance the reception delay amount of the IP content to the reception device is transmitted to the plurality of reception devices that have established the session, and each of the reception devices responds to the delay amount confirmation request. A delay amount measuring means for measuring the reception delay amount of each of the plurality of receiving devices by receiving response information;
The receiving apparatus having the largest reception delay amount so as to match the arrival time of the IP content of the receiving apparatus having the largest reception delay amount while determining the distribution order of the IP contents in the descending order of the measured reception delay amount. The distribution time to each of the receiving devices is calculated based on the distribution time of the IP content to the reference time, and distribution time information including the determined distribution order and the calculated distribution time is generated and stored in the storage unit A delivery time determination means,
Content transmitting means for transmitting the IP content to each of a plurality of receiving devices by the established session at the calculated distribution time based on the determined distribution order;
Function as
The storage means further stores a required time (L) associated with communication I / F processing required for one data distribution,
In the calculation of the distribution time to each of the receiving devices, the distribution time determining means,
Based on the following formula (1), an ideal delivery time (T _n ) to the receiving device whose delivery order is nth is calculated,
_{T n = t 1 + (RDT} 1 -RDT n) ... formula (1)
Furthermore, based on the following formula (2), the actual distribution time (t _n-1 ) of the IP content with the previous distribution order and the ideal distribution time (T _n ) of the IP content with the distribution order Whether or not there is more than the required time (L),
_{T n <t n-1 +} L ... formula (2)
When the expression (2) is not satisfied, the ideal delivery time (T _n ) is stored as the actual delivery time (t _n ) in the delivery time information,
When the expression (2) is satisfied, based on the following expression (3), the time obtained by adding the required time (L) to the actual distribution time (t _n-1 ) of the IP content of the previous distribution order Is stored in the distribution time information as the actual distribution time (t _n )
_{t n = t n-1 +} L ... formula (3)
Content distribution program to function as

Here, t ₁ is the said reference point, a distribution time of the IP content delivery order is delivered to the first. RDT _n is the reception delay amount of the IP content distributed in the nth distribution order. t _n is the actual distribution time of the IP content to the receiving apparatus of the nth distribution order.

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