JP4650513B2 - Content distribution system, network, and channel switching control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a content distribution system capable of switching a radio channel type used for broadcast services without deteriorating the use efficiency of radio resources. <P>SOLUTION: User terminals 101-103 receive the same contents on PtP channels 1-3. If a total sum of the downlink transmit power of these PtP channels is greater than the downlink transmit power of a single PtM channel in the case of distributing contents to the user terminals 101-103 on the PtM channel, it is determined that the radio channel for distributing contents to the user terminals 101-103 is switched from the PtP channels 1-3 to the PtM channel. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a content distribution system, a network, and a channel switching control method, and more particularly to a content distribution system that switches the type of a wireless channel used for content distribution.

  The broadcast service is a so-called broadcast-type service that simultaneously provides the same content to a plurality of user terminals located within the cell of each base station. As long as a user terminal receiving a broadcast service in a cell is within the area, the user terminal should be able to receive content with a certain quality of service (QoS). Power must be supplied.

  The broadcast service is realized by a point-to-multipoint (PtM) method or a point-to-point (PtP) method.

  The PtM scheme is a scheme in which content is distributed to all user terminals in a cell using a single point-to-multipoint channel (common channel) that the base station reaches to the cell boundary, and is also called a common channel scheme.

  In the PtM method, a single downlink radio channel is used and the user terminal receives it. Therefore, even if many user terminals receiving the broadcast service receive content at the same time, the number of user terminals is increased. Regardless, the base station does not need to increase the transmission power of the radio channel.

  Therefore, the PtM scheme can achieve high use efficiency of radio resources when the number of user terminals receiving the broadcast service in the cell is large. If the downlink power capacity is sufficient for the broadcast service, the base station adjusts the downlink transmission power of the PtM channel so that it can reach the cell boundary, so that content can be transmitted to all user terminals in the cell. It is possible to deliver. On the other hand, when there is no margin in the downlink power capacity, the base station adjusts the downlink transmission power of the PtM channel to a value smaller than the downlink transmission power at which the PtM channel can reach the cell boundary. Therefore, in this case, it is possible to distribute the content to some user terminals in the cell. However, for example, the user terminal near the cell boundary cannot receive the PtM channel, Cannot receive.

  The PtP scheme is a scheme in which a base station distributes the same content to each user terminal that receives a broadcast service in a cell using a point-to-point channel (dedicated channel), and is also called an individual channel scheme.

  The PtP method is used when there are relatively few user terminals that receive a broadcast service in a cell. Since the dedicated channel is used in the PtP scheme, the base station can set the downlink transmission power of the dedicated channel to an appropriate value by transmission power control. Therefore, when the number of user terminals is small, it is possible to reduce the amount of downlink transmission power for distributing content to these user terminals.

  As described above, there are the PtM method and the PtP method as a method for realizing the broadcast service, and it is necessary to determine which of the PtM method and the PtP method is used.

  Non-Patent Document 1 describes that a radio channel type (point-to-multipoint or point-to-point) is determined based on the number of user terminals that receive a broadcast service in a cell.

  Thus, when determining the radio channel type based on the number of user terminals receiving the broadcast service in the cell, the PtP channel is selected if the number of user terminals is less than or equal to the threshold, and the PtM if the number of user terminals is greater than the threshold. It is conceivable to use a channel.

3GPP TR 23.8446 1.2.0, September 2002, p. 17

  However, the method of determining the radio channel type used for content distribution based on the number of user terminals receiving the broadcast service in the cell has the following problems.

  For example, when the content is distributed through a single PtM channel to a user terminal that receives a broadcast service in a cell, if the number of user terminals changes and falls below a threshold, the wireless channel used for content distribution is The PtM channel is switched to the PtP channel, and content is distributed to each of the user terminals via the PtP channel. However, when all user terminals are near the cell boundary, there is a problem that the total transmission power of the PtP channel to these user terminals may be larger than the transmission power of the PtM channel.

  That is, when the radio channel used for content distribution is switched based on the number of user terminals, there is a problem in that the use efficiency of radio resources may be deteriorated due to this switching.

  An object of the present invention is to provide a content distribution system, a network, and a channel switching control method capable of switching a radio channel type used for a broadcast service without reducing the use efficiency of radio resources.

A mobile station according to the present invention has a receiving means for receiving content from the base station via a dedicated channel in the mobile station of the content distribution system having a base station and a plurality of mobile stations, Based on the transmission power amount and the downlink transmission power amount of the common channel when a common channel is used for the distribution, the content distribution system determines whether to switch the dedicated channel to the common channel, When the dedicated channel and the dedicated channel of another mobile station are switched to the common channel in order from the channel with the smallest downlink transmission power, the receiving unit is configured to transmit the base station from the base station via the switched common channel. It is characterized by receiving content . In addition, the mobile station according to the present invention comprises: a receiving means for receiving content from the base station via a common channel in the mobile station of the content distribution system having a base station and a plurality of mobile stations; Based on the transmission power amount and the downlink transmission power amount of the dedicated channel when the dedicated channel is used for the distribution, the content distribution system determines whether to switch the common channel to the dedicated channel, When the dedicated channel is used for the distribution, the dedicated channel is assigned in order from the mobile station that receives the content via the dedicated channel with large downlink transmission power, and the common channel is switched to the dedicated channel, A receiving means receives the content from the base station via the switched dedicated channel. Receiving a, characterized in that.

  A channel switching control method according to the present invention is a channel switching control method for a content distribution system for distributing content to a mobile station, wherein the base station is based on a power amount for distributing the content from a base station to the mobile station. A channel switching determination step of determining whether to switch the type of communication channel from the mobile station to the mobile station.

  The network according to the present invention includes channel switching determining means for determining whether to switch the type of communication channel from the base station to the mobile station based on the amount of power for content distribution from the base station to the mobile station. It is characterized by that.

  A channel switching control method according to the present invention is a channel switching control method for a network that distributes content to a mobile station, from the base station based on an amount of power for distributing the content from the base station to the mobile station. It is characterized by determining whether or not to switch the type of communication channel to the mobile station.

  According to the present invention, it is determined whether or not to switch the type of communication channel from the base station to the mobile station based on the amount of power for content distribution from the base station to the mobile station. Therefore, it is possible to prevent the use efficiency of radio resources from being lowered by switching the type of communication channel used for content distribution.

  The effect of the present invention is that the radio channel type used for the broadcast service can be switched without reducing the use efficiency of radio resources. The reason is that it is determined whether to switch the radio channel type from the base station to the mobile station based on the amount of power for content distribution from the base station to the mobile station. With this method, it is possible to select a radio channel type suitable for radio resource conditions.

  Embodiments of the present invention will be described below with reference to the drawings. In all the drawings shown below, equivalent parts are denoted by the same reference numerals.

  FIG. 1 is a diagram showing the configuration of a mobile communication system (content distribution system) according to an embodiment of the present invention. As shown in FIG. 1, a mobile communication system according to an embodiment of the present invention includes user terminals 101 to 103 which are mobile stations (MS), base station apparatuses (BS) 201 and 202, and a base station control apparatus (RNC: Radio Network Controller) 301, network connection device 401, and broadcast content server 501.

  The user terminals 101 to 103 are carried / carried by a user who receives a mobile communication service, and can receive the mobile communication service in an area covered by the mobile communication system. Base station apparatuses 201 and 202 are installed in an area covered by the mobile communication system.

  When user terminals 101-103 are in the cell of base station apparatus 201, user terminals 101-103 can communicate with base station apparatus 201 through a wireless medium. When user terminals 101-103 are in the cell of base station apparatus 202, user terminals 101-103 can communicate with base station apparatus 202 through a wireless medium.

  Base station apparatuses 201 and 202 are connected to network connection apparatus 401 via base station control apparatus 301. Base station control apparatus 301 has a function of relaying received signals and between each user terminal and each base station apparatus. A function of assigning a radio channel for transmitting a radio signal; Base station apparatuses 201 and 202 and base station control apparatus 301 constitute a RAN (Radio Access Network).

  The network connection device 401 is connected to, for example, a public telephone line network, a public data line network, a private line network, a facility (not shown) such as various service providers, and is also connected to the broadcast content server 501. The broadcast content server 501 holds various contents for a broadcast service that is one of mobile communication services. The contents of the broadcast content server 501 are distributed to users who have contracted with various service providers, and are transmitted to the user terminals 101 to 103 via the network connection device 401, the base station control device 301, and the base station device 201 or 202. be delivered.

  There are point-to-multipoint (PtM) and point-to-point (PtP) as wireless channel types for simultaneously delivering the same content to user terminals 101 to 103 that receive the broadcast service.

  According to the embodiment of the present invention, when the user terminals 101 to 103 receive content through the PtP channel (individual channel), the sum of the downlink transmission power of these PtP channels and a single PtM channel (common channel) Based on the downlink transmission power of this PtM channel when delivering content to the user terminals 101 to 103, it is determined whether or not to switch the radio channel for delivering content from the PtP channel to a single PtM channel. The

  When the user terminals 101 to 103 are receiving content through a single PtM channel, the downlink transmission power of this PtM channel and the PtP channel of these PtP channels when content is distributed to the user terminals 101 to 103 via the PtP channel Based on the total downlink transmission power, it is determined whether or not to switch the radio channel for distributing content from the PtM channel to the PtP channel.

  When switching the wireless channel type, switching is performed so that the content received by the user terminals 101 to 103 is not interrupted, or switching is performed with interruption.

  When switching without interrupting the content, the other type of wireless channel is set while maintaining the wireless channel currently used for content distribution to the user terminals 101 to 103. In addition, over a period in which these different types of radio channels are set together, all the user terminals (user terminals 101 to 103 and user terminals 101 to 103 in the cell of the base station) are transmitted from the base station transmitting content to the user terminals 101 to 103. Switching is performed so that the total transmission power to a user terminal (not shown not receiving broadcast service) does not exceed the upper limit of transmission power that the base station can release into the cell.

  When switching is performed with content interruption, the wireless channel currently used for content distribution to the user terminals 101 to 103 is released, and the other type of wireless channel is set. Also in this case, switching is performed so that the sum of the downlink transmission powers of the base station does not exceed the upper limit over the switching period.

  Hereinafter, the operation of the mobile communication system according to the embodiment of the present invention when a plurality of user terminals receiving the broadcast service in the cell of the base station 201 is receiving content through the PtP channel will be described with reference to the drawings.

  2 and 3 are flowcharts showing the operation of the mobile communication system according to the embodiment of the present invention when a broadcast service is provided on the PtP channel.

  2 and 3, the user terminal in the cell of the base station 201 requests to receive the broadcast service, or the user terminal already requesting to receive the broadcast service is in the cell. When it comes in, it is activated. That is, it is activated when the number of user terminals that receive the broadcast service on the PtP channel in the cell increases.

  Alternatively, the processing procedures shown in FIGS. 2 and 3 may be started periodically at predetermined intervals. The reason why the processing procedures shown in FIGS. 2 and 3 are periodically started is that even if the number of user terminals receiving the broadcast service on the PtP channel does not change, the PtP channel must be switched from the PtP channel to the PtM channel depending on the position of the user terminal. This is because a situation that must be performed may occur. For example, when the user terminal receiving the broadcast service on the PtP channel moves and the downlink transmission power of the PtP channel increases (generally when the user terminal moves away from the base station antenna), the above situation is Can occur.

  Alternatively, the processing procedure shown in FIGS. 2 and 3 may be started when the number of allowable receiving users of the broadcast service is reduced. As a classification of mobile communication services of a mobile communication system, a broadcast service that provides the same content to a plurality of users, and a non-provided service that is individually provided to each user such as a telephone service and an e-mail service There is a broadcast service. An opportunity to increase or decrease the number of allowable receiving users of the broadcast service or the non-broadcast service is determined by the distribution of services provided to users located in each wireless area. When the number of allowable receiving users of the broadcast service is reduced, the amount of transmission power that can be used for the broadcast service is restricted, and the number of user terminals that can distribute content on the PtP channel is reduced. Therefore, the processing procedure shown in FIGS. 2 and 3 is activated, and it is determined whether or not to switch from the PtP channel to the PtM channel. In this case, a part of user terminals that require more power may not be able to receive content.

  Alternatively, the processing procedure shown in FIGS. 2 and 3 may be activated when the number of allowable receiving users of the non-broadcast service is increased. When the allowable number of receiving users of the non-broadcast service is increased, the amount of transmission power that can be used for the broadcast service is reduced, and the number of user terminals that can distribute content through the PtP channel is reduced. Therefore, the processing procedure shown in FIGS. 2 and 3 is activated, and it is determined whether or not to switch from the PtP channel to the PtM channel. In this case as well, some user terminals that require more power may not be able to receive content. Alternatively, when the total transmission power of the PtP channel currently used for content distribution exceeds a preset value, the processing procedure shown in FIGS. 2 and 3 may be activated.

  When the above-described activation conditions are satisfied and the processing procedure illustrated in FIGS. 2 and 3 is activated, the base station control device 301 is used by a plurality of user terminals that receive the broadcast service in the cell of the base station 201. The base station 201 is requested to recognize the transmission power of all PtP channels. Then, the base station 201 recognizes the transmission power of all the PtP channels, and the base station 201 or the base station control device 301 obtains the sum (TTL_PtP) of these (step S1). By reporting the transmission power recognized by the base station 201 to the base station control apparatus 301, the base station control apparatus 301 can obtain the total (TTL_PtP).

  The base station 201 or the base station control device 301 is a user terminal (hereinafter referred to as a first user terminal) that receives content on a PtP channel (hereinafter referred to as a first PtP channel) having the maximum power among the transmission power of the PtP channel. The transmission power required when the PtM channel is used to distribute the content is estimated. That is, the transmission power (Max_PtM) of the PtM channel that reaches the first user terminal is estimated (step S2). The transmission power (Max_PtM) of the PtM channel can be estimated based on the transmission power of the first PtP channel and the measurement information from the first user terminal. The measurement information from the first user terminal is information on the reception power of the first PtP channel. When estimating in step S2, the measurement information received from the first user terminal is measured by the first user terminal. Report to the station 201 or the base station controller 301.

  The base station 201 or the base station control device 301 compares the total transmission power (TTL_PtP) of the PtP channel with the transmission power (Max_PtM) of the PtM channel that reaches the first user terminal (step S3). If the sum (TTL_PtP) is smaller than the transmission power (Max_PtM) (step S3, No), it is not determined that it is necessary to switch from the PtP channel to the PtM channel, and this flow ends and a new activation condition occurs. Wait until.

  On the other hand, if the total sum (TTL_PtP) is equal to or greater than the transmission power (Max_PtM) (Yes in Step S3), it is determined that the PtP channel is switched to the PtM channel, and the base station 201 or the base station controller 301 determines whether the cell of the base station 201 The power margin (Mgn_PW) is evaluated (step S4). The power margin (Mgn_PW) is an upper limit value of transmission power that can be released into the cell by the base station 201, and all user terminals in the cell from the base station 201 (user terminals receiving broadcast service in the cell and non-synchronization in the cell). It is a difference with the sum total of transmission power to the user terminal receiving the information service.

  The base station 201 or the base station controller 301 receives a user terminal (hereinafter referred to as a second PtP channel) having a minimum power (Min_PtP) among the transmission power of the PtP channel (hereinafter referred to as a second PtP channel). The transmission power required when the PtM channel is used to distribute content to a user terminal) is estimated. That is, the transmission power (Min_PtM) of the PtM channel that reaches the second user terminal is estimated (step S5). The transmission power (Min_PtM) can be estimated based on the transmission power of the second PtP channel or measurement information from the second user terminal. The measurement information from the second user terminal is information on the received power of the second PtP channel. When estimating in step S5, the second user terminal is made to measure the received power of the second PtP channel and It can be obtained by causing the station 201 or the base station control device 301 to report.

  Here, since the transmission power of the PtP channel obtained in step S1 may be different from the value initially evaluated due to the movement of the terminal or the like, the transmission power of all PtP channels may be re-evaluated in step S5. .

  The base station 201 or the base station control device 301 compares the power margin (Mgn_PW) with the transmission power (Min_PtM) of the PtM channel reaching the second user terminal (step S6). If the power margin (Mgn_PW) is equal to or greater than the transmission power (Min_PtM) of the PtM channel that reaches the second user terminal (step S6, Yes), the second user terminal does not interrupt content reception. The PtP channel is switched to the PtM channel (step S7). In this channel switching process, a PtM channel that reaches the second user terminal is established while maintaining the second PtP channel, and the channel for delivering content to the second user terminal is the second PtP. The channel is switched to the established PtM channel.

  On the other hand, if the power margin (Mgn_PW) is smaller than the transmission power (Min_PtM) of the PtM channel that reaches the second user terminal (step S6, No), the base station 201 or the base station control device 301 determines the power margin (Mgn_PW). ) Plus the transmission power (Min_PtP) of the second PtP channel and the transmission power (Min_PtM) of the PtM channel reaching the second user terminal (step S8). If “Mgn_PW + Min_PtP ≧ Min_PtM” (step S8, Yes), the channel switching process of the second user terminal with content interruption is performed (step S9). In this channel switching process, the PtM channel that reaches the second user terminal is established after releasing the second PtP channel, and the second user terminal receives the content on the established PtM channel. Accordingly, the reception of content is interrupted at the second user terminal until the PtM channel reaching the second user terminal is established after the second PtP channel is released.

  If “Mgn_PW + Min_PtP <Min_PtM” (step S8, No), channel switching processing for a plurality of user terminals receiving the broadcast service in the cell of the base station 201 is performed with content interruption (step S10). In this channel switching process, after releasing the PtP channel used for content distribution to the plurality of user terminals, a PtM channel that reaches all of the plurality of user terminals is established, and the plurality of user terminals are established PtM Receive content on the channel. Of course, this channel switching process is performed so that the sum of the downlink transmission power amounts of the base station 201 does not exceed the upper limit value of the transmission power that the base station 201 can release into the cell 100. In addition, if the channel switching process in step S10 is performed for all the user terminals receiving the broadcast service in the cell, the downlink transmission power amount of the base station 201 is reduced during the channel switching process in step S10. The sum does not exceed the upper limit. The reason is that the transmission power (Max_PtM) of the PtM channel reaching the first user terminal is equal to or less than the sum of transmission powers of the PtP channel (TTL_PtP) (see step S3).

  After step S7, step S9, and step S10, the process proceeds to step S11. The base station 201 or the base station control device 301 holds a target list in which all user terminals that receive the broadcast service in the cell of the base station 201 are registered in advance, and is switched from the PtP channel to the PtM channel in the previous step. The user terminal is deleted from the target list (step S11). The base station 201 or the base station control device 301 determines whether there is a user terminal to be switched from the PtP channel to the PtM channel based on the target list (step S12).

  If there is still a user terminal that receives the broadcast service on the PtP channel (step S12, Yes), the process proceeds to step S4. On the other hand, if all the user terminals receiving the broadcast service have received the content through the PtM channel (No in step S12), this flow is terminated and the process waits until a new activation condition occurs.

  In the above-described target list, not all user terminals that receive the broadcast service in the cell are registered, but only a part of user terminals that receive the broadcast service in the cell are registered. Also good. In this case, a state in which the PtP channel and the PtM channel are mixed in the cell may occur temporarily or constantly.

  If the power margin (Mgn_PW) is smaller than the transmission power (Min_PtM) in step S6, it is determined in step S8 whether to perform the channel switching process in step S9 or the channel switching process in step S10. The processes of S8 and S9 may not be performed. In this case, if the power margin (Mgn_PW) is smaller than the transmission power (Min_PtM) in step S6, the channel switching process in step S10 is performed.

  If the sum (TTL_PtP) is greater than or equal to the transmission power (Max_PtM) in step S3 (step S3, Yes), it is determined to switch from the PtP channel to the PtM channel. However, even if the total sum (TTL_PtP) is equal to or higher than the transmission power (Max_PtM), it may not be determined that switching is performed depending on the security attribute of the content. For example, when the content is paid content, the switching may not be performed.

  Next, the channel switching process in step S7 shown in FIG. 3 will be described in detail with reference to the drawings.

  FIG. 6 is a diagram showing a situation in which user terminals 101 to 103 located in the cell 100 of the base station 201 are receiving content through the PtP channels 1 to 3, and the same parts as those in FIG. Yes. In FIG. 6, the base station 201 transmits content to the user terminal 101 using the PtP channel 1, transmits content to the user terminal 102 using the PtP channel 2, and transmits content to the user terminal 103 using the PtP channel 3. Sending. It is assumed that the transmission power of PtP channel 1 is the largest and the transmission power of PtP channel 3 is the smallest among the transmission powers of PtP channels 1 to 3 from base station 201 to user terminals 101 to 103.

  FIG. 17 is a sequence chart showing an operation when the channel switching process of step S7 shown in FIG. 3 is performed in the situation shown in FIG. When the channel switching process of step S7 shown in FIG. 3 is performed in the situation shown in FIG. 6, the base station controller 301, as shown in FIG. 17, the PtM channel 13 reaching the user terminal 103 (see FIG. 7). A PtM channel transmission start message is sent to the base station 201 so as to start transmission (step A1). In response to receiving the PtM channel transmission start message, the base station 201 starts transmission of the PtM channel 13 while maintaining the PtP channel 3 as shown in FIG. A message is returned (step A2).

  In response to the reception of the transmission start completion message, the base station control apparatus 301 sends a switching instruction message for instructing to receive the content not on the PtP channel 3 but on the PtM channel 13 to the user terminal 103 (step A3). . In response to the reception of the switching instruction message, the user terminal 103 enters an operation of receiving content on the PtM channel 13 and confirms that the content can be received satisfactorily on the PtM channel 13, and then notifies the base station controller 301 of the switching completion message. Is returned (step A4).

  In response to receiving the switching completion message, the base station control device 301 sends a PtP channel transmission stop message for releasing the PtP channel 3 to the base station 201 (step A5), and the base station 201 sends a transmission stop message. When receiving, transmission of the PtP channel 3 is stopped. As a result, the radio channel used for content distribution to the user terminal 103 is switched from the PtP channel 3 to the PtM channel 13, and the user terminal 103 receives the content on the PtM channel 13 as shown in FIG.

  Note that before sending the switching instruction message in step A3, the base station 201 or the base station control apparatus 301 stops the content reception on the PtP channel 3 and inquires whether the content can be received on the PtM channel 13. An inquiry message may be sent to the user terminal 103, and a switching instruction message may be sent when a response is received from the user terminal 103.

  However, if the user terminal 103 returns a response indicating that the content cannot be normally received as a result of sending the inquiry message, the current transmission power of the PtP channel 3 and the measurement by the user terminal 103 are performed. The transmission power of the PtM channel 13 is readjusted on the basis of the current reception power of the PtP channel 3 to be executed. Then, after the transmission power of the PtM channel 13 is readjusted, an inquiry message is sent to the user terminal 103 again.

  As described above, in FIG. 8, the user terminal 101 receives content on the PtP channel 1, the user terminal 102 receives content on the PtP channel 2, and the user terminal 103 receives content on the PtM channel 13. It is shown.

  FIG. 18 is a sequence chart showing an operation when the channel switching process of step S7 shown in FIG. 3 is performed in the situation shown in FIG. When the channel switching process in step S7 shown in FIG. 3 is performed in the situation shown in FIG. 8, the base station controller 301 makes the PtM channel 13 reach the user terminal 102 as shown in FIG. A PtM channel transmission power increase message for increasing the transmission power of is transmitted to the base station 201 (step A6). In response to receiving the transmission power increase message, the base station 201 increases the transmission power of the PtM channel 13. As a result, a PtM channel 12 that reaches the user terminal 102 is generated as shown in FIG. Since the transmission power of the PtM channel 12 reaching the user terminal 102 has already been estimated in step S5 shown in FIG. 2, the base station 201 determines the transmission power of the PtM channel 13 based on the estimated transmission power. By increasing, the PtM channel 12 can be generated.

  When the base station 201 generates the PtM channel 12, it returns a transmission power increase completion message to the base station controller 301 (step A7). In response to the reception of the transmission power increase completion message, the base station controller 301 sends a switching instruction message for instructing to receive the content not on the PtP channel 2 but on the PtM channel 12 to the user terminal 102 (step A8). ). In response to the reception of the switching instruction message, the user terminal 102 enters an operation of receiving content on the PtM channel 12 and confirms that the content can be normally received on the PtM channel 12, and then notifies the base station controller 301 of the switching completion message. Is returned (step A9).

  In response to receiving the switching completion message, the base station control device 301 sends a PtP channel transmission stop message for releasing the PtP channel 2 to the base station 201 (step A10), and the base station 201 sends a transmission stop message. When receiving, transmission of the PtP channel 2 is stopped. As a result, the radio channel used for content distribution to the user terminal 102 is switched from the PtP channel 2 to the PtM channel 12, and the user terminals 102 and 103 receive the content on the PtM channel 12 as shown in FIG.

  Before sending the switching instruction message in step A8, the base station 201 or the base station control device 301 stops content reception on the PtP channel 2 and inquires whether it is possible to receive content on the PtM channel 12. An inquiry message may be sent to the user terminal 102, and a switching instruction message may be sent when there is a response from the user terminal 102 that it is possible.

  However, when a response indicating that the content cannot be normally received is returned from the user terminal 102 as a result of sending the inquiry message, the current transmission power of the PtP channel 2 and the measurement by the user terminal 102 are performed. The transmission power of the PtM channel 12 is readjusted based on the current received power of the PtP channel 2 to be executed. After the transmission power of the PtM channel 12 is readjusted, an inquiry message is sent to the user terminal 102 again.

  As described above, FIG. 10 shows a situation in which only the user terminal 101 receives content on the PtP channel 1 and the user terminals 102 and 103 receive content on the PtM channel 12.

  FIG. 19 is a sequence chart showing an operation when the channel switching process of step S7 shown in FIG. 3 is performed in the situation shown in FIG. When the channel switching process of step S7 shown in FIG. 3 is performed in the situation shown in FIG. 10, the base station controller 301 causes the PtM channel 12 to reach the user terminal 101 as shown in FIG. A PtM channel transmission power increase message for increasing the transmission power of is transmitted to the base station 201 (step A11). In response to receiving the transmission power increase message, the base station 201 increases the transmission power of the PtM channel 12. As a result, a PtM channel 11 that reaches the user terminal 101 is generated as shown in FIG. Since the transmission power of the PtM channel 11 reaching the user terminal 101 has already been estimated in step S5 shown in FIG. 2, the base station 201 determines the transmission power of the PtM channel 12 based on the estimated transmission power. By increasing, the PtM channel 11 can be generated.

  When the base station 201 generates the PtM channel 11, it returns a transmission power increase completion message to the base station controller 301 (step A12). In response to the reception of the transmission power increase completion message, the base station controller 301 sends a switching instruction message for instructing to receive the content not on the PtP channel 1 but on the PtM channel 11 to the user terminal 101 (step A13). ). In response to the reception of the switching instruction message, the user terminal 101 enters an operation of receiving content on the PtM channel 11 and confirms that the content can be normally received on the PtM channel 11, and then notifies the base station controller 301 of the switching completion message. Is returned (step A14).

  In response to receiving the switching completion message, the base station control device 301 sends a PtP channel transmission stop message for releasing the PtP channel 1 to the base station 201 (step A15), and the base station 201 sends a transmission stop message. When receiving, transmission of the PtP channel 1 is stopped. As a result, the radio channel used to distribute the content to the user terminal 101 is switched from the PtP channel 1 to the PtM channel 11, and all of the user terminals 101 to 103 receive the content on the PtM channel 11 as shown in FIG.

  Note that before sending the switching instruction message in step A13, the base station 201 or the base station control device 301 stops the content reception on the PtP channel 1 and inquires whether the content can be received on the PtM channel 11. An inquiry message may be sent to the user terminal 101, and a switching instruction message may be sent when a response is received from the user terminal 101.

  However, if the user terminal 101 returns a response indicating that the content cannot be normally received as a result of sending the inquiry message, the current transmission power of the PtP channel 1 and the measurement by the user terminal 101 are performed. The transmission power of the PtM channel 11 is readjusted based on the current reception power and the like of the PtP channel 1 to be executed. Then, after the transmission power of the PtM channel 11 is readjusted, an inquiry message is sent to the user terminal 101 again.

  In the channel switching process of step S7 shown in FIG. 3, a plurality of PtP channels currently used for content distribution to a plurality of user terminals may be switched to a PtM channel at a time. When the channel switching process in step S7 shown in FIG. 3 is performed for a plurality of user terminals, the total downlink transmission power of the base station 201 is set while the PtM channel is set while maintaining the plurality of PtP channels. Of course, it is necessary not to exceed the upper limit.

  A case will be described in which the channel switching process in step S7 shown in FIG. 3 is performed on the user terminals 102 and 103 in the situation shown in FIG. FIG. 23 is a sequence chart showing an operation when the channel switching process of step S7 shown in FIG. 3 is performed on the user terminals 102 and 103 in the situation shown in FIG. In this process, the transmission power of the PtM channel reaching the user terminal 102 is estimated in step S5 shown in FIG. 2, and the estimated transmission power and the margin power (in the cell 100) in step S6 shown in FIG. (Mgn_PW), and it is confirmed that the estimated transmission power is equal to or less than the margin power (Mgn_PW).

  When the channel switching process in step S7 shown in FIG. 3 is performed on the user terminals 102 and 103 in the situation shown in FIG. 6, the base station control apparatus 301 reaches the user terminal 102 as shown in FIG. A PtM channel transmission start message is sent to the base station 201 to start transmission of the PtM channel 12 (see FIG. 13) (step C1). In response to the reception of the PtM channel transmission start message, the base station 201 starts transmission of the PtM channel 12 while maintaining the PtP channels 2 and 3 as shown in FIG. A start completion message is returned (step C2).

  In response to the reception of the transmission start completion message, the base station controller 301 sends a switching instruction message to the user terminals 102 and 103 to instruct to receive the content on the PtM channel 12 instead of the PtP channels 2 and 3. (Steps C3 and C4). In response to receiving the switching instruction message, the user terminals 102 and 103 enter an operation of receiving content on the PtM channel 12 and switch to the base station controller 301 when confirming that the content can be normally received on the PtM channel 12. A completion message is returned (steps C5 and C7).

  In response to receiving the switch completion message from the user terminals 102 and 103, the base station control device 301 sends a PtP channel transmission stop message for releasing the PtP channels 2 and 3 to the base station 201 (steps C6 and C6). C8) When the base station 201 receives the transmission stop message, the base station 201 stops transmission of the PtP channels 2 and 3. As a result, the radio channel used for content distribution to the user terminals 102 and 103 is switched from the PtP channels 2 and 3 to the PtM channel 12, and the user terminals 102 and 103 receive the content on the PtM channel 12 as shown in FIG. To do.

  In this way, by switching a plurality of PtP channels to the PtM channel at a time, all the PtP channels used for the broadcast service in the cell 100 can be switched to the PtM channel earlier.

  Next, a case where the channel switching process in step S7 shown in FIG. 3 is performed on the user terminals 101 to 103 receiving the broadcast service in the cell 100 in the situation shown in FIG. Note that this processing is performed by the PtM channel 11 (FIG. 14) reaching the user terminal 1 having the margin power (Mgn_PW) in the cell 100 in step S6 shown in FIG. 3 and the transmission power (Max_PtM) estimated in step S2. And the transmission power (Max_PtM) is confirmed to be equal to or less than the margin power (Mgn_PW).

  This process is realized by slightly modifying the procedure shown in FIG. When the channel switching process in step S7 shown in FIG. 3 is performed on the user terminals 101 to 103 in the situation shown in FIG. 6, the base station control device 301 determines that the PtM channel 11 reaching the user terminal 101 in step C1. A transmission start message is sent to the base station 201 to start transmission (see FIG. 14). Therefore, the base station 201 starts transmission of the PtM channel 11 while maintaining the PtP channels 1 to 3 as shown in FIG.

  When transmitting the switching instruction message in steps C3 and C4, the base station control apparatus 301 also transmits a switching instruction message for instructing to receive the content not on the PtP channel 1 but on the PtM channel 11 to the user terminal 101. Therefore, the user terminals 101 to 103 enter an operation of receiving content on the PtM channel 11, and the user terminal 101 confirms that the content can be normally received on the PtM channel 11 as in the case of the user terminals 102 and 103. A switching completion message is returned to the control device 301.

  In step C6 and C8, the base station controller 301 sends a transmission stop message for releasing the PtP channels 2 and 3 to the base station 201, and in response to receiving the switch completion message from the user terminal 101, PtP A transmission stop message for releasing channel 1 is sent to the base station 201. Accordingly, the base station 201 stops transmission of the PtP channels 1 to 3. As a result, the radio channel used to distribute the content to the user terminals 101 to 103 is switched from the PtP channels 1 to 3 to the PtM channel 11, and the user terminals 101 to 103 receive the content on the PtM channel 11 as shown in FIG. To do.

  In addition, when the base station 201 starts transmission of the PtM channel while maintaining the PtP channel, the PtM channel is transmitted with the transmission power estimated in advance as described above, but there is a slight margin from the transmission power estimated in advance. You may make it transmit a PtM channel with the electric power which has. Thereby, it is possible to prevent the user terminal that should receive the PtM channel from moving away from the base station 201 and not receiving the PtM channel. When a user terminal that receives content on the PtM channel detects an error in the received data, an error detection notification is sent to the base station 201, and the base station 201 responds to the error detection notification to increase the transmission power of the PtM channel. You may make it increase.

  For example, in the channel switching process of step S7 shown in FIG. 3 for all the user terminals 101 to 103, the base station 201 starts transmission of the PtM channel 11 while maintaining the PtP channels 1 to 3 as shown in FIG. Instead of this, transmission of the PtM channel 10 having transmission power higher than that of the PtM channel 11 may be started as shown in FIG. In this case, the radio channel used for content distribution to the user terminals 101 to 103 is switched from the PtP channels 1 to 3 to the PtM channel 10, and the user terminals 101 to 103 receive the content on the PtM channel 10 as shown in FIG. Will do.

  When the channel switching process of step S7 shown in FIG. 3 is performed in the situation shown in FIG. 10, the channel switching process of step S7 shown in FIG. 3 is performed for all the user terminals 101 to 103. 12, after the user terminals 101 to 103 receive the content on the PtM channel 11 as shown in FIG. 12, the base station 201 increases the transmission power of the PtM channel 11, and the PtM channel as shown in FIG. 15. 10 may be generated. Of course, even if the PtM channel 10 that reaches the vicinity of the boundary of the cell 100 is generated as described above, it is necessary that the sum of the downlink transmission power of the base station 201 does not exceed the upper limit value.

  Next, the channel switching process in step S9 shown in FIG. 3 will be described in detail with reference to the drawings.

  FIG. 20 is a sequence chart showing an operation when the channel switching process of step S9 shown in FIG. 3 is performed in the situation shown in FIG. When the channel switching process of step S9 shown in FIG. 3 is performed in the situation shown in FIG. 6, the base station control apparatus 301 stops receiving the content on the PtP channel 3 as shown in FIG. A switching preparation instruction message is sent to the user terminal 103 to instruct the user terminal 103 to prepare for receiving content on the PtM channel 13 (see FIG. 8) that arrives (step B1). The switching preparation instruction message includes time information at which the PtM channel 13 can be received. When receiving the switching preparation instruction message, the user terminal 103 returns a switching preparation completion message to the base station controller 301 (step B2).

  In response to receiving the switch preparation completion message, the base station control device 301 sends a transmission stop message for releasing the PtP channel 3 to the base station 201 (step B3), and the base station 201 receives the transmission stop message. Then, transmission of the PtP channel 3 is stopped. Then, the base station 201 returns a transmission stop completion message to the base station control device 301 (step B4).

  When receiving the transmission stop completion message, the base station control apparatus 301 sends a transmission start message for instructing to start transmission of the PtM channel 13 reaching the user terminal 103 to the base station 201 (step B5). In response to reception of the transmission start message, the base station 201 starts transmission of the PtM channel 13 as shown in FIG. 8, and returns a transmission start completion message to the base station controller 301 (step B6).

  The user terminal 103 starts the content reception operation on the PtM channel 13 at the time designated by the switching preparation instruction message. As a result, the radio channel used to distribute the content to the user terminal 103 is switched from the PtP channel 3 to the PtM channel 13, and the user terminal 103 receives the content on the PtM channel 13 as shown in FIG.

  FIG. 21 is a sequence chart showing an operation when the channel switching process of step S9 shown in FIG. 3 is performed in the situation shown in FIG. When the channel switching process of step S9 shown in FIG. 3 is performed in the situation shown in FIG. 8, the base station control device 301 stops receiving the content on the PtP channel 2 as shown in FIG. A switching preparation instruction message is sent to the user terminal 102 to instruct to make preparations for receiving content on the reaching PtM channel 12 (see FIG. 10) (step B7). The switching preparation instruction message includes time information at which the PtM channel 12 can be received. When receiving the switching preparation instruction message, the user terminal 102 returns a switching preparation completion message to the base station control apparatus 301 (step B8).

  In response to the reception of the switch preparation completion message, the base station controller 301 sends a transmission stop message for releasing the PtP channel 2 to the base station 201 (step B9), and the base station 201 receives the transmission stop message. Then, transmission of the PtP channel 2 is stopped. Then, the base station 201 returns a transmission stop completion message to the base station control device 301 (step B10).

  When receiving the transmission stop completion message, the base station controller 301 sends a transmission power increase message for increasing the transmission power of the PtM channel 13 to the base station 201 so that the PtM channel 13 reaches the user terminal 102 (step B11). ). In response to receiving the transmission power increase message, the base station 201 increases the transmission power of the PtM channel 13. As a result, a PtM channel 12 that reaches the user terminal 102 is generated as shown in FIG. Then, the base station 201 returns a transmission power increase completion message to the base station control device 301 (step B12).

  The user terminal 102 starts content reception operation on the PtM channel 12 at the time designated by the switching preparation instruction message. As a result, the radio channel used for content distribution to the user terminal 102 is switched from the PtP channel 2 to the PtM channel 12, and the user terminals 102 and 103 receive content on the PtM channel 12 as shown in FIG. .

  FIG. 22 is a sequence chart showing an operation when the channel switching process of step S9 shown in FIG. 3 is performed in the situation shown in FIG. When the channel switching process of step S9 shown in FIG. 3 is performed in the situation shown in FIG. 10, the base station controller 301 stops the content reception on the PtP channel 1 as shown in FIG. A switching preparation instruction message is sent to the user terminal 101 to instruct to make preparations for receiving content on the reaching PtM channel 11 (see FIG. 12) (step B13). The switching preparation instruction message includes time information at which the PtM channel 11 can be received. When receiving the switching preparation instruction message, the user terminal 101 returns a switching preparation completion message to the base station control device 301 (step B14).

  In response to receiving the switch preparation completion message, the base station control device 301 sends a transmission stop message for releasing the PtP channel 1 to the base station 201 (step B15), and the base station 201 receives the transmission stop message. Then, the transmission of the PtP channel 1 is stopped. Then, the base station 201 returns a transmission stop completion message to the base station control device 301 (step B16).

  When receiving the transmission stop completion message, the base station controller 301 sends a transmission power increase message for increasing the transmission power of the PtM channel 12 to the base station 201 so that the PtM channel 12 reaches the user terminal 101 (step B17). ). In response to receiving the transmission power increase message, the base station 201 increases the transmission power of the PtM channel 12. As a result, a PtM channel 11 that reaches the user terminal 101 is generated as shown in FIG. Then, the base station 201 returns a transmission power increase completion message to the base station control device 301 (step B18).

  The user terminal 101 starts content reception operation on the PtM channel 11 at the time designated by the switching preparation instruction message. As a result, the radio channel used for content distribution to the user terminal 101 is switched from the PtP channel 1 to the PtM channel 11, and the user terminals 101 to 103 receive the content on the PtM channel 11 as shown in FIG. .

  Next, the channel switching process in step S10 shown in FIG. 3 will be described in detail with reference to the drawings.

  FIG. 24 is a sequence chart showing an operation in the case where the channel switching process (the process of switching the PtP channels 2 and 3 to the PtM channel at a time) shown in FIG. 3 is performed in the situation shown in FIG. When the channel switching process in step S10 shown in FIG. 3 is performed in the situation shown in FIG. 6, the base station controller 301 stops the content reception on the PtP channels 2 and 3 as shown in FIG. A switching preparation instruction message is sent to the user terminals 102 and 103 to instruct to prepare to receive content on the PtM channel 12 (see FIG. 10) that reaches 102 (steps D1 and D2). Each of the switching preparation instruction messages includes time information at which the PtM channel 12 can be received. Upon receiving the switching preparation instruction message, the user terminals 102 and 103 return a switching preparation completion message to the base station control device 301 (steps D3 and D6).

  In response to receiving the switch preparation completion message from the user terminals 102 and 103, the base station control apparatus 301 sends a transmission stop message for releasing the PtP channels 2 and 3 to the base station 201 (steps D4 and D7). When the base station 201 receives these transmission stop messages, the base station 201 stops transmission of the PtP channels 2 and 3. Then, the base station 201 returns a transmission stop completion message to the base station control device 301 (steps D5 and D8).

  When receiving the transmission stop completion message, the base station control device 301 sends a transmission start message for instructing to start transmission of the PtM channel 12 reaching the user terminal 102 to the base station 201 (step D9). In response to receiving the transmission start message, the base station 201 starts transmission of the PtM channel 12 as shown in FIG. 10, and returns a transmission start completion message to the base station controller 301 (step D10).

  The user terminals 102 and 103 start the content reception operation on the PtM channel 12 at the time designated by the switching preparation instruction message. As a result, the radio channel used for content distribution to the user terminals 102 and 103 is switched from the PtP channels 2 and 3 to the PtM channel 12, and the user terminals 102 and 103 receive the content on the PtM channel 12 as shown in FIG. Will come to do.

  In FIG. 24, the PtP channels 2 and 3 are released and the PtM channel 12 is established, but the PtP channels 1 to 3 are released and the PtM channel 11 reaching the user terminal 1 is established. Of course it is good. In this case, in the situation shown in FIG. 6, PtP channels 1 to 3 are released, and as shown in FIG. 12, PtM channel 11 reaching user terminal 1 is established, and user terminals 101 to 103 receive content on PtM channel 11. To do.

  Next, referring to the drawings, the operation of the mobile communication system according to the embodiment of the present invention when a plurality of user terminals receiving the broadcast service in the cell of the base station 201 is receiving content through a single PtM channel. I will explain.

  4 and 5 are flowcharts illustrating the operation of the mobile communication system according to the embodiment of the present invention when a broadcast service is provided on the PtM channel.

  4 and 5, the user terminal receiving the broadcast service in the cell of the base station 201 cancels the reception of the broadcast service or receives the broadcast service in the cell of the base station 201. It is activated when the user terminal escapes from the cell. That is, it is activated when the number of user terminals that receive the broadcast service on the PtM channel in the cell decreases. For example, by measuring the entry / exit of a user terminal receiving a broadcast service to / from a cell, or sending a request signal requesting the user terminal to report its location, if necessary, to report the location. Thus, the base station 201 and the base station control device 301 can recognize the number.

  Alternatively, the processing procedures shown in FIGS. 4 and 5 may be periodically activated at predetermined intervals. The reason why the processing procedure shown in FIGS. 4 and 5 is periodically started is that even if the number of user terminals receiving the broadcast service on the PtM channel does not change, the PtM channel must be switched from the PtM channel to the PtP channel depending on the position of the user terminal. This is because a situation that must be performed may occur. For example, when the user terminal receiving the broadcast service on the PtM channel moves to a position that does not require transmission power from the initial position (generally, when the user terminal approaches the base station antenna), the above situation may occur. Can occur.

  Alternatively, the processing procedure shown in FIGS. 4 and 5 may be started when the number of allowable receiving users of the broadcast service is increased. When the number of allowable receiving users of the broadcast service increases, the amount of transmission power that can be used for the broadcast service increases, and the number of user terminals that can distribute content on the PtP channel increases. Therefore, the processing procedure shown in FIGS. 4 and 5 is activated, and it is determined whether or not to switch from the PtM channel to the PtP channel.

  Alternatively, the processing procedure shown in FIGS. 4 and 5 may be started when the number of allowed receiving users of the non-broadcast service is reduced. If the allowable number of users receiving the non-broadcast service is reduced, the amount of transmission power that can be used for the broadcast service increases, and the number of user terminals that can distribute content on the PtP channel increases. Therefore, the processing procedure shown in FIGS. 4 and 5 is activated, and it is determined whether or not to switch from the PtM channel to the PtP channel.

  When the above-described activation conditions are satisfied and the processing procedure illustrated in FIGS. 4 and 5 is activated, the base station 201 or the base station control device 301 can receive a plurality of broadcast services on the PtM channel in the cell of the base station 201. The transmission power of the PtP channel when content is distributed to all the user terminals via the PtP channel is estimated, and the sum (TTL_PtP) of these is obtained (step T1). For the transmission power of these PtP channels, the reception power of the radio channel transmitted from the base station 201 to the plurality of user terminals is measured by the plurality of user terminals, and the measurement results are reported to the base station 201 or the base station control device 301. Can be estimated. The wireless channel is a PtM channel currently used for content distribution, a perch channel received by each of the plurality of user terminals, or the like. Notification of measurement results from the plurality of user terminals may be performed passively in response to reception of a measurement request instruction transmitted from the base station 201 or the base station control apparatus 301, or the plurality of user terminals may be notified. You may make it a user terminal perform voluntarily or periodically.

  Then, the base station 201 or the base station control device 301 evaluates the transmission power (Max_PTM) of the PtM channel currently used for content distribution to the plurality of user terminals (step T2). The base station 201 or the base station control device 301 compares the sum (TTL_PtP) obtained in step T1 with the transmission power (Max_PtM) obtained in step T2 (step T3). If the sum (TTL_PtP) is equal to or greater than the transmission power (Max_PtM) (No at Step T3), it is not determined that it is necessary to switch from the PtM channel to the PtP channel, and this flow ends and waits until a new activation condition occurs. .

  On the other hand, if the sum (TTL_PtP) is smaller than the transmission power (Max_PtM) (step T3, Yes), the base station 201 or the base station controller 301 determines that the PtM channel is switched to the PtP channel. The power margin (Mgn_PW) in the cell is evaluated (step T4). The power margin (Mgn_PW) is an upper limit value of transmission power that can be released into the cell by the base station 201, and all user terminals in the cell from the base station 201 (user terminals receiving broadcast service in the cell and non-synchronization in the cell). It is a difference with the sum total of transmission power to the user terminal receiving the information service.

  The base station 201 or the base station control device 301 specifies a PtP channel (hereinafter referred to as a first PtP channel) having the maximum power (Max_PtP) among the transmission power of the PtP channel estimated in step T1 (step S1). T5). In step T5, the transmission power of the PtP channel may be estimated again to identify the first PtP channel having the maximum power (Max_PtP).

  The base station 201 or the base station control device 301 compares the power margin (Mgn_PW) with the estimated transmission power (Max_PtP) of the first PtP channel (step T6). If the power margin (Mgn_PW) is equal to or greater than the estimated transmission power (Max_PtP) of the first PtP channel (step T6, Yes), the user who should receive the content on the first PtP channel among the plurality of user terminals A process of switching the PtM channel currently used for content distribution to the first user terminal to the first PtP channel so that reception of the content is not interrupted at the terminal (hereinafter referred to as the first user terminal). Performed (step T7). In this channel switching process, the first PtP channel is established in a state where the PtM channel is maintained, and the first PtP channel in which a channel for delivering content to the first user terminal is established from the PtM channel Is switched to.

  On the other hand, if the power margin (Mgn_PW) is smaller than the estimated transmission power (Max_PtP) of the first PtP channel (step T6, No), the base station 201 or the base station controller 301 is estimated in step T1. The user terminal (hereinafter referred to as the second user terminal) that should receive the PtP channel (hereinafter referred to as the second PtP channel) having the second largest transmission power among the transmission powers of the PtP channels. The transmission power (2nd_PtM) of the PtM channel is estimated (step T8). The transmission power (2nd_PtM) of the PtM channel reaching the second user terminal is the transmission power of the PtM channel currently used for content distribution to the plurality of user terminals, and this PtM channel or perch in the second user terminal. It can be estimated based on the received power of the channel.

  The base station 201 or the base station controller 301 transmits the PtM channel transmission power (Max_PTM) currently used for content distribution to the plurality of user terminals and the PtM channel transmission power (2nd_PtM) reaching the second user terminal. And a value obtained by adding the difference to the power margin (Mgn_PW) to the transmission power (Max_PtP) of the first PtP channel (step T9). If “Mgn_PW + (Max_PTM−2nd_PtM) ≧ Max_PtP” (step T9, Yes), the channel switching process of the first user terminal accompanied by the interruption of the content is performed (step T10). In this channel switching process, the transmission power of the PtM channel currently used for content distribution to the plurality of user terminals is reduced so that it reaches the second user terminal but cannot reach the first user terminal. Then, a first PtP channel is established, and the first user terminal receives content on the established first PtP channel. Therefore, reception of content is interrupted at the first user terminal from when the PtM channel reaching the second user terminal is generated until the first PtP channel is established.

  If “Mgn_PW + (Max_PTM−2nd_PtM) <Max_PtP” (step T9, No), channel switching processing for a plurality of user terminals receiving the broadcast service in the cell of the base station 201 is performed with interruption of content ( Step T11). In this channel switching process, the transmission power of the PtM channel used for content distribution to the plurality of user terminals is reduced so that the plurality of user terminals cannot be reached or the PtM channel is released, and then the plurality of users A PtP channel is established between the terminal and the base station 201, and the plurality of user terminals receive content through the established PtP channel. Of course, this channel switching process is performed so that the sum of the downlink transmission power amounts of the base station 201 does not exceed the upper limit value of the transmission power that the base station 201 can release into the cell 100. If the channel switching process in step T11 is performed for all user terminals receiving the broadcast service in the cell, the sum of the downlink transmission power amounts of the base station 201 during the channel switching process in step T11. Does not exceed the upper limit. This is because the sum (TTL_PtP) obtained in step T1 is smaller than the transmission power (Max_PtM) obtained in step T2 (see step T3).

  After step T7, step T10, and step T11, the process proceeds to step T12. The base station 201 or the base station control device 301 holds in advance a target list in which all user terminals that receive the broadcast service in the cell of the base station 201 are registered, and the user terminal that has been switched to the PtP channel in the previous step Is deleted from the target list (step T12). The base station 201 or the base station control device 301 determines whether there is a user terminal to be switched to the PtP channel based on the target list (step T13).

  If there is still a user terminal that receives the broadcast service on the PtM channel (step T13, Yes), the process proceeds to step T4. On the other hand, if all user terminals receiving the broadcast service have received the content through the PtP channel (No at step T13), this flow is terminated and a new start condition is awaited.

  In the above-described target list, not all user terminals that receive the broadcast service in the cell are registered, but only a part of user terminals that receive the broadcast service in the cell are registered. Also good. In this case, a state in which the PtM channel and the PtP channel are mixed in the cell may occur temporarily or constantly.

  If the power margin (Mgn_PW) is smaller than the transmission power (Max_PtP) in step T6, it is determined in step T9 whether to perform the channel switching process in step T10 or the channel switching process in step T11. You may make it not perform the process of T8-T10. In this case, if the power margin (Mgn_PW) is smaller than the transmission power (Max_PtP) in step T6, the channel switching process in step T11 is performed.

  If the sum (TTL_PtP) is equal to or greater than the transmission power (Max_PtM) in step T3, it is determined that there is no need to switch from the PtM channel to the PtP channel. However, even if the total sum (TTL_PtP) is equal to or greater than the transmission power (Max_PtM), it may be determined that switching is performed depending on the security attribute of the content. For example, when the content is paid content, the PtM channel may be switched to the PtP channel.

  Next, the channel switching process in step T7 shown in FIG. 5 will be described in detail with reference to the drawings.

  FIG. 25 is a sequence chart showing an operation when the channel switching process of step T7 shown in FIG. 5 is performed in the situation shown in FIG. When the channel switching process in step T7 shown in FIG. 5 is performed in the situation shown in FIG. 12, the base station controller 301 starts transmission of the PtP channel 1 (see FIG. 11) as shown in FIG. A transmission start message is sent to the base station 201 (step E1). In response to receiving the transmission start message, the base station 201 starts transmission of the PtP channel 1 to the user terminal 101 while maintaining the PtM channel 11 as shown in FIG. A transmission start completion message is returned (step E2).

  In response to the reception of the transmission start completion message, the base station control apparatus 301 sends a switching instruction message for instructing to receive the content not on the PtM channel 11 but on the PtP channel 1 to the user terminal 101 (step E3). . In response to receiving the switching instruction message, the user terminal 101 enters an operation of receiving content on the PtP channel 1 and confirms that the content can be normally received on the PtP channel 1, and then notifies the base station controller 301 of the switching completion message. Is returned (step E4).

  In response to receiving the switching completion message, the base station controller 301 decreases the transmission power of the PtM channel 11 so that the PtM channel 11 does not reach the user terminal 101 but reaches the user terminal 102. Is sent to the base station 201 (step E5). In response to receiving the transmission power reduction message, the base station 201 decreases the transmission power of the PtM channel 11. As a result, a PtM channel 12 that reaches the user terminal 102 is generated as shown in FIG. When the base station 201 generates the PtM channel 12, it returns a transmission power reduction completion message to the base station controller 301 (step E6). Therefore, as shown in FIG. 10, the user terminal 101 receives content on the PtP channel 1, and the user terminals 102 and 103 receive content on the PtM channel 12.

  Note that, in the situation shown in FIG. 15, it is also possible to perform the channel switching process in step T7 shown in FIG. When performing the channel switching process of step T7 shown in FIG. 5 in the situation shown in FIG. 15, the base station 201 starts transmission of the PtP channel 1 to the user terminal 101 while maintaining the PtM channel 10, and the user terminal 101 After starting content reception on the PtP channel 1, the base station 201 generates the PtM channel 12 by reducing the transmission power of the PtM channel 10 as shown in FIG.

  FIG. 26 is a sequence chart showing an operation when the channel switching process of step T7 shown in FIG. 5 is performed in the situation shown in FIG. When the channel switching process in step T7 shown in FIG. 5 is performed in the situation shown in FIG. 10, the base station controller 301 starts transmission of the PtP channel 2 (see FIG. 9) as shown in FIG. A transmission start message is sent to the base station 201 (step E7). In response to receiving the transmission start message, the base station 201 starts transmission of the PtP channel 2 to the user terminal 102 while maintaining the PtM channel 12 as shown in FIG. A transmission start completion message is returned (step E8).

  In response to the reception of the transmission start completion message, the base station control device 301 sends a switching instruction message for instructing to receive the content not on the PtM channel 12 but on the PtP channel 2 to the user terminal 102 (step E9). . In response to the reception of the switching instruction message, the user terminal 102 enters an operation of receiving content on the PtP channel 2 and confirms that the content can be normally received on the PtP channel 2, and then notifies the base station controller 301 of the switching completion message. Is returned (step E10).

  In response to receiving the switching completion message, the base station control device 301 transmits a transmission power decrease message for reducing the transmission power of the PtM channel 12 so that the PtM channel 12 does not reach the user terminal 102 but reaches the user terminal 103. Is sent to the base station 201 (step E11). In response to receiving the transmission power decrease message, the base station 201 decreases the transmission power of the PtM channel 12. As a result, a PtM channel 13 that reaches the user terminal 103 is generated as shown in FIG. When the base station 201 generates the PtM channel 13, it returns a transmission power reduction completion message to the base station controller 301 (step E12). Therefore, as shown in FIG. 8, user terminals 101 and 102 receive content on PtP channels 1 and 2, and user terminal 103 receives content on PtM channel 13.

  FIG. 27 is a sequence chart showing an operation when the channel switching process of step T7 shown in FIG. 5 is performed in the situation shown in FIG. When the channel switching process of step T7 shown in FIG. 5 is performed in the situation shown in FIG. 8, the base station controller 301 starts transmission of the PtP channel 3 (see FIG. 7) as shown in FIG. A transmission start message is sent to the base station 201 (step E13). In response to receiving the transmission start message, the base station 201 starts transmission of the PtP channel 3 to the user terminal 103 while maintaining the PtM channel 13 as shown in FIG. A transmission start completion message is returned (step E14).

  In response to the reception of the transmission start completion message, the base station control device 301 sends a switching instruction message for instructing to receive the content not on the PtM channel 13 but on the PtP channel 3 to the user terminal 103 (step E15). . In response to receiving the switching instruction message, the user terminal 103 enters an operation of receiving content on the PtP channel 3 and confirms that the content can be normally received on the PtP channel 3, and then notifies the base station controller 301 of the switching completion message. Is returned (step E16).

  In response to receiving the switching completion message, the base station control device 301 sends a transmission stop message for releasing the PtM channel 13 to the base station 201 (step E17). When the base station 201 receives the transmission stop message, The transmission of the PtM channel 13 is stopped. Therefore, as shown in FIG. 6, the user terminals 101 to 103 receive content through the PtP channels 1 to 3.

  As described above, the actual transmission power of the PtP channels 1 to 3 is initially estimated by switching the radio channel used for content distribution to the user terminals 101 to 103 from the PtM channel 11 to the PtP channels 1 to 3. When the transmission power amount is larger than the total transmission power amount (total (TTL_PtP) obtained in step T1 shown in FIG. 4), the original PtM channel 11 may be switched back to.

  When the channel switching process in step T7 shown in FIG. 5 is performed, as described above, only one terminal among a plurality of user terminals receiving content on the PtM channel is switched to the PtP channel. The user terminal may be switched to the PtP channel at the same time. When performing the channel switching process of step T7 shown in FIG. 5 for a plurality of user terminals in this way, the base station 201 is in the process of transmitting the PtP channel to the plurality of user terminals while maintaining the PtM channel. Of course, it is necessary that the total sum of the downlink transmission powers does not exceed the upper limit.

  A case will be described in which the channel switching processing in step T7 shown in FIG. 5 is performed on the user terminals 101 and 102 in the situation shown in FIG. Note that this processing compares the total estimated transmission power of the PtP channels 1 and 2 with the margin power (Mgn_PW) in the cell 100 in step T6 shown in FIG. This is performed after it has been confirmed that the total sum of the estimated transmission powers is equal to or less than the margin power (Mgn_PW).

  When the channel switching process of step T7 shown in FIG. 5 is performed on the user terminals 101 and 102 in the situation shown in FIG. 12, the base station 201 maintains the PtM channel 11 and the PtP channel 1 to the user terminal 101. And the user terminal 101 and 102 start receiving content on the PtP channels 1 and 2, and then the base station 201 transmits the PtM channel 11 as shown in FIG. By reducing the power, the PtM channel 13 is generated. As a result, as shown in FIG. 8, the user terminals 101 and 102 receive the content on the PtP channels 1 and 2, and the user terminal 103 receives the content on the PtM channel 13. Of course, the operation of the base station 201 described above is controlled by the base station controller 301.

  The case where the channel switching process of step T7 shown in FIG. 5 is performed on the user terminals 101 to 103 in the situation shown in FIG. In this process, in step T6 shown in FIG. 5, the estimated total transmission power of the PtP channels 1 to 3 is compared with the margin power (Mgn_PW) in the cell 100, and the PtP channels 1 to 3 are compared. This is performed after it has been confirmed that the total sum of the estimated transmission powers is equal to or less than the margin power (Mgn_PW).

  When the channel switching process of step T7 shown in FIG. 5 is performed on the user terminals 101 to 103 in the situation shown in FIG. 12, the base station 201 maintains the PtM channel 11 as shown in FIG. After starting transmission of PtP channel 1 to 101, PtP channel 2 to user terminal 102, and PtP channel 3 to user terminal 103, and user terminals 101 to 103 start receiving content on PtP channels 1 to 3, As shown in FIG. 6, the base station 201 stops transmission of the PtM channel 11. As a result, as shown in FIG. 6, the user terminals 101 to 103 receive content through the PtP channels 1 to 3. Of course, the operation of the base station 201 described above is controlled by the base station controller 301.

  Next, the channel switching process in step T10 shown in FIG. 5 will be described in detail with reference to the drawings.

  FIG. 28 is a sequence chart showing an operation when the channel switching process of step T10 shown in FIG. 5 is performed in the situation shown in FIG. When the channel switching process of step T10 shown in FIG. 5 is performed in the situation shown in FIG. 12, the base station controller 301 stops content reception on the PtM channel 11 as shown in FIG. 10), a switching preparation instruction message for instructing preparation for receiving content is sent to the user terminal 101 (step F1). The switching preparation instruction message includes time information at which the PtP channel 1 can be received. When receiving the switching preparation instruction message, the user terminal 101 returns a switching preparation completion message to the base station control apparatus 301 (step F2).

  In response to receiving the switch preparation completion message, the base station controller 301 decreases the transmission power for reducing the transmission power of the PtM channel 11 so that the PtM channel 11 does not reach the user terminal 101 but reaches the user terminal 102. A message is sent to the base station 201 (step F3). In response to receiving the transmission power reduction message, the base station 201 decreases the transmission power of the PtM channel 11. Thereby, the PtM channel 12 reaching the user terminal 102 is generated. When the base station 201 generates the PtM channel 12, it returns a transmission power reduction completion message to the base station controller 301 (step F4).

  In response to receiving the transmission power reduction completion message, the base station control device 301 sends a transmission start message to the base station 201 to start transmission of the PtP channel 1 (step F5). In response to receiving the transmission start message, the base station 201 starts transmission of the PtP channel 1 to the user terminal 101 as shown in FIG. The user terminal 101 starts receiving content on the PtP channel 1 at the time designated by the switching preparation instruction message. Therefore, as shown in FIG. 10, the user terminal 101 receives content on the PtP channel 1, and the user terminals 102 and 103 receive content on the PtM channel 12.

  FIG. 29 is a sequence chart showing an operation when the channel switching process of step T10 shown in FIG. 5 is performed in the situation shown in FIG. When the channel switching process of step T10 shown in FIG. 5 is performed in the situation shown in FIG. 10, the base station controller 301 stops content reception on the PtM channel 12 as shown in FIG. 8), a switching preparation instruction message for instructing preparation for receiving content is sent to the user terminal 102 (step F6). The switching preparation instruction message includes time information at which the PtP channel 2 can be received. When receiving the switching preparation instruction message, the user terminal 102 returns a switching preparation completion message to the base station control apparatus 301 (step F7).

  In response to the reception of the switch preparation completion message, the base station control device 301 decreases the transmission power for reducing the transmission power of the PtM channel 12 so that the PtM channel 12 does not reach the user terminal 102 but reaches the user terminal 103. A message is sent to the base station 201 (step F8). In response to receiving the transmission power decrease message, the base station 201 decreases the transmission power of the PtM channel 12. As a result, the PtM channel 13 that reaches the user terminal 103 is generated. When the base station 201 generates the PtM channel 13, it returns a transmission power reduction completion message to the base station controller 301 (step F9).

  In response to receiving the transmission power reduction completion message, the base station control apparatus 301 sends a transmission start message to the base station 201 to start transmission of the PtP channel 2 (step F10). In response to receiving the transmission start message, the base station 201 starts transmission of the PtP channel 2 to the user terminal 102 as shown in FIG. The user terminal 102 starts content reception operation on the PtP channel 2 at the time designated by the switching preparation instruction message. Therefore, as shown in FIG. 8, the user terminals 101 and 102 receive content on the PtP channels 1 and 2, and the user terminal 103 receives content on the PtM channel 13.

  FIG. 30 is a sequence chart showing an operation when the channel switching process of step T10 shown in FIG. 5 is performed in the situation shown in FIG. When the channel switching process of step T10 shown in FIG. 5 is performed in the situation shown in FIG. 8, the base station controller 301 stops content reception on the PtM channel 13 as shown in FIG. (See FIG. 6), a switching preparation instruction message for instructing preparation for receiving content is sent to the user terminal 103 (step F11). The switching preparation instruction message includes time information at which the PtP channel 3 can be received. When receiving the switching preparation instruction message, the user terminal 103 returns a switching preparation completion message to the base station controller 301 (step F12).

  In response to receiving the switch preparation completion message, the base station control device 301 sends a transmission stop message for releasing the PtM channel 13 to the base station 201 (step F13). The base station 201 stops the transmission of the PtM channel 13 in response to the reception of the transmission stop message, and returns a transmission stop completion message to the base station control device 301 (step F14).

  In response to receiving the transmission stop completion message, the base station control device 301 sends a transmission start message to the base station 201 to start transmission of the PtP channel 3 (step F15). In response to receiving the transmission start message, the base station 201 starts transmission of the PtP channel 3 to the user terminal 103 as shown in FIG. The user terminal 103 starts the content reception operation on the PtP channel 3 at the time designated by the switching preparation instruction message. Therefore, as shown in FIG. 6, the user terminals 101 to 103 receive content through the PtP channels 1 to 3.

  Next, the channel switching process in step T11 shown in FIG. 5 will be described.

  In the situation shown in FIG. 12, by performing the channel switching process in step T11 shown in FIG. 5, the radio channels used for content distribution to the user terminals 101 and 102 are changed from PtM channel 11 to PtP channels 1 and 2 (see FIG. 8). When switching at once, the base station 201 reduces the transmission power of the PtM channel 11 so that the PtM channel 11 does not reach the user terminals 101 and 102 but reaches the user terminal 103. As a result, the PtM channel 13 that reaches the user terminal 103 is generated.

  Then, the base station 201 starts transmission of the PtP channel 1 to the user terminal 101 and transmission of the PtP channel 2 to the user terminal 102 as shown in FIG. Then, as shown in FIG. 8, the user terminals 101 and 102 receive the content through the PtP channels 1 and 2. Of course, the operation of the base station 201 described above is controlled by the base station controller 301.

  In the situation shown in FIG. 12, by performing the channel switching process in step T11 shown in FIG. 5, the radio channels used for content distribution to the user terminals 101 to 103 are changed from PtM channel 11 to PtP channels 1 to 3 (see FIG. 6). May be switched at once. In this case, the base station 201 stops transmission of the PtM channel 11. Then, the base station 201 starts transmission of the PtP channel 1 to the user terminal 101, transmission of the PtP channel 2 to the user terminal 102, and transmission of the PtP channel 3 to the user terminal 103 as shown in FIG. Then, as shown in FIG. 6, the user terminals 101 to 103 receive content through the PtP channels 1 to 3. Of course, the operation of the base station 201 described above is controlled by the base station controller 301.

  As described above, in each of the channel switching processes in steps S7, S9, S10, T7, T10, and T11 shown in FIGS. 3 and 5, the type of the radio channel is switched under the control of the base station controller 301. That is, the base station control device 301 has channel switching control means for switching the type of the radio channel, and steps S7, S9, S10, T7, T10 shown in FIGS. Each of the channel switching processes of T11 is realized. Further, in each of steps S3 and T3 shown in FIGS. 2 and 4, it is determined whether or not to switch the type of the radio channel. As described above, this determination is made by either the base station 201 or the base station controller 301. You may go. That is, the base station 201 or the base station controller 301 has channel switching determination means for determining whether or not to switch the type of the radio channel, and this channel switching determination means is currently used for content distribution. Based on the downlink transmission power amount of one channel and the downlink transmission power amount of the second channel when the second channel of a different type from the first channel is used for content distribution, It is determined whether or not to switch to the second channel.

  Content includes content that is not desired to be interrupted and content that may be interrupted. Content that is not desirable to be interrupted is content that is continuously delivered and causes dissatisfaction for the user when the delivery is interrupted, such as a movie or a relay image. On the other hand, content that can be interrupted is delivered, for example, intermittently and repeatedly, and even if delivery is interrupted, the user can obtain lost data again and is delivered repeatedly at certain intervals. Notification information.

  Each of the channel switching processes of steps S9, S10, T10, and T11 shown in FIGS. 3 and 5 is a channel switching process with content interruption as described above, but is distributed to user terminals that receive the broadcast service. When the content is content that is not desired to be interrupted, it is not desirable to perform channel switching processing that is accompanied by content interrupt. Therefore, if the content is content that is not desirably interrupted, the channel switching process that accompanies the content may not be performed.

  In order for the base station control device 301 to know whether the content from the broadcast content server 501 is undesirable for the content to be interrupted, the broadcast content server 501 receives the broadcast distribution of the content from the broadcast content server 501. When started or during the broadcast of content, the base station controller 301 is notified of the content attributes, that is, whether the content is undesirable for the content. Thereby, the base station control apparatus 301 can determine whether or not the channel switching process with content interruption may be performed.

  FIG. 31 shows an operation in which the broadcast content server 501 notifies the base station control apparatus 301 of content attributes. FIG. 31A is a sequence chart showing an operation of notifying content attributes when content distribution is started, and FIG. 31B shows notification of content attributes or change of attributes during content distribution. It is a sequence chart which shows operation | movement to notify.

  In FIG. 31A, the broadcast content server 501 sends a content attribute notification message for notifying the content attribute when the distribution of the content is started (step G1). A content attribute notification confirmation message is transmitted to notify the broadcast content server 501 that the notification of the attribute of (2) has been received (step G2). In FIG. 31B, the broadcast content server 501 sends a content attribute change notification message notifying the content attribute or notifying the change of the attribute during the distribution of the content (step G3), and the base station control device 301. Sends a content attribute change notification confirmation message for notifying the broadcast content server 501 that the content attribute has been notified (step G4).

It is a figure which shows the structure of the mobile communication system by the Example of this invention. 3 is a flowchart illustrating an operation of a mobile communication system according to an embodiment of the present invention when a broadcast service is provided on a PtP channel. 3 is a flowchart illustrating an operation of a mobile communication system according to an embodiment of the present invention when a broadcast service is provided on a PtP channel. 3 is a flowchart illustrating an operation of a mobile communication system according to an embodiment of the present invention when a broadcast service is provided on a PtM channel. 3 is a flowchart illustrating an operation of a mobile communication system according to an embodiment of the present invention when a broadcast service is provided on a PtM channel. It is a figure for demonstrating operation | movement of the mobile communication system by the Example of this invention. It is a figure for demonstrating operation | movement of the mobile communication system by the Example of this invention. It is a figure for demonstrating operation | movement of the mobile communication system by the Example of this invention. It is a figure for demonstrating operation | movement of the mobile communication system by the Example of this invention. It is a figure for demonstrating operation | movement of the mobile communication system by the Example of this invention. It is a figure for demonstrating operation | movement of the mobile communication system by the Example of this invention. It is a figure for demonstrating operation | movement of the mobile communication system by the Example of this invention. It is a figure for demonstrating operation | movement of the mobile communication system by the Example of this invention. It is a figure for demonstrating operation | movement of the mobile communication system by the Example of this invention. It is a figure for demonstrating operation | movement of the mobile communication system by the Example of this invention. It is a figure for demonstrating operation | movement of the mobile communication system by the Example of this invention. 5 is a sequence chart showing an operation of the mobile communication system according to the embodiment of the present invention. 5 is a sequence chart showing an operation of the mobile communication system according to the embodiment of the present invention. 5 is a sequence chart showing an operation of the mobile communication system according to the embodiment of the present invention. 5 is a sequence chart showing an operation of the mobile communication system according to the embodiment of the present invention. 5 is a sequence chart showing an operation of the mobile communication system according to the embodiment of the present invention. 5 is a sequence chart showing an operation of the mobile communication system according to the embodiment of the present invention. 5 is a sequence chart showing an operation of the mobile communication system according to the embodiment of the present invention. 5 is a sequence chart showing an operation of the mobile communication system according to the embodiment of the present invention. 5 is a sequence chart showing an operation of the mobile communication system according to the embodiment of the present invention. 5 is a sequence chart showing an operation of the mobile communication system according to the embodiment of the present invention. 5 is a sequence chart showing an operation of the mobile communication system according to the embodiment of the present invention. 5 is a sequence chart showing an operation of the mobile communication system according to the embodiment of the present invention. 5 is a sequence chart showing an operation of the mobile communication system according to the embodiment of the present invention. 5 is a sequence chart showing an operation of the mobile communication system according to the embodiment of the present invention. 5 is a sequence chart showing an operation of the mobile communication system according to the embodiment of the present invention.

Explanation of symbols

1 to 3 PtP channels 10 to 13 PtM channels 100 cells 101 to 103 User terminals 201 and 202 Base station 301 Base station controller 401 Network connection device 501 Broadcast content server

Claims (6)

In the mobile station of the content distribution system having a base station and a plurality of mobile stations,
Receiving means for receiving content from the base station via a dedicated channel;
Whether or not to switch the dedicated channel to the common channel based on the downlink transmission power amount of the dedicated channel and the downlink transmission power amount of the common channel when a common channel is used for the distribution. When the channel is switched to the common channel sequentially from the channel with the smallest downlink transmission power among the dedicated channel and the dedicated channel of another mobile station ,
The mobile station , wherein the receiving means receives the content from the base station via the switched common channel . In the mobile station of the content distribution system having a base station and a plurality of mobile stations,
Receiving means for receiving content from the base station via a common channel;
Whether or not to switch the common channel to the dedicated channel based on the downlink transmission power amount of the common channel and the downlink transmission power amount of the dedicated channel when the dedicated channel is used for the distribution. is determined by the order individual channel from the mobile station for receiving the content via a dedicated channel downlink transmission power is greater in the case of using the delivery an individual channel is allocated, the common channel is switched to the dedicated channel If you are Ru,
The mobile station , wherein the receiving means receives the content from the base station via the switched dedicated channel . In response to a change in the number of the mobile station, whether to switch the type of communication channel to the mobile station from the base station, according to claim 1, characterized in that it is determined by the content distribution system or 2. The mobile station according to 2 . Characterized in that in response to a change in the allowable number of receiving stations service of distributing the content, whether to switch the type of communication channel to the mobile station from the base station is determined by the content distribution system The mobile station according to claim 1 or 2 . In response to the allowable number of receiving stations change in services other than the service of distributing the content, whether to switch the type of communication channel to the mobile station from the base station is determined by the content distribution system The mobile station according to claim 1 or 2, characterized in that The switching from the base station of the type of communication channel to the mobile station, the mobile station according to any one of claims 1-5, characterized in that it is switched in the service of distributing the content.

Images