Broadcast system, broadcast management device, broadcast method, and terminal

Provided is a broadcast system that assigns a communication channel to a program and broadcasts data for the program to terminals, the broadcast system including a broadcast management device and a communication access network device. The management device calculates as a score a measure of viewing requests from users of the terminals for a plurality of programs, and determines a program to actually broadcast on the communication channel based on the score. The communication access network device transmits program data on a communication channel according to the determination of the broadcast management device.

The present application is the National Phase of PCT/JP2009/055739, filed Mar. 24, 2009, which claims the benefit of priority based on Japanese Patent Application No. 2008-086614 filed on Mar. 28, 2008, disclosure of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a data communication technique for delivering same data to a number of terminals in a communication system.

BACKGROUND ART

In a wireless communication system that covers its communication area with cells formed by wireless base stations, positioning of multiple cells enables communication between wireless terminals over a large area. In Worldwide Interoperability for Microwave Access (WiMAX), communication at various places is enabled by covering a communication area with small size cells called femtocells. There is a form of communication in which program data is broadcast to multiple wireless terminals in this type of wireless communication system (see JP2005-516474A and JP2007-174645A).

In a band available for a wireless communication system, multiple wireless channels are defined, from which a wireless channel for broadcasting programs is selected. On the selected wireless channel, program data is broadcast from a wireless base station. A user can watch the program by receiving data on the wireless channel on which the program is broadcast with a wireless terminal.

General wireless terminals for viewing broadcasts of this kind include fixed terminals represented by home radios or televisions and mobile terminals that can be carried by users. Also, schemes for broadcasting programs include a scheme which releases programs in advance prior to their broadcast and carries out broadcast according to the programs as well as a scheme which temporarily changes programs for announcing an emergency or for extending a program that is currently on air.

In a wireless communication system, however, radio resources are limited. Besides, because wireless channels are also used for point-to-point calls, the number of wireless channels available for program broadcast is further limited.

Meanwhile, in view of the situation in which wireless channels available for program broadcast are not sufficient despite a host of programs, it is desirable to have a communication scheme to select some provided programs and broadcast only the selected programs.

As an example, when there are ten programs and each of the programs requires a radio band of 1 MHz, a radio band of 10 MHz is necessary for broadcasting all the programs. In reality, however, such a situation is possible where only a radio band of 3 MHz is available. In such a case, three out of the ten programs would have to be selected.

One method of selection is to broadcast programs as previously scheduled without consideration of users' preferences. In this method, users can reliably learn when and which programs are broadcast by referring to a program table published beforehand. However, programs really desired by users are less likely to be broadcast. Although there is a technique to take into account users' preferences in selection of broadcast programs (see JP2001-313922A (paragraphs 0023 and 0024)), the technique does not reflect users' preferences in broadcast programs in real time.

While the descriptions here illustrate a wireless communication system as an example, broadcast of program data is similarly performed in a wired communication system as well. In addition, that the communication resources may be limited is also true for a wired communication system.

DISCLOSURE OF THE INVENTION

Since the number of communication channels available for program broadcast is limited in such a communication system as mentioned above, it is not possible to assign wireless channels to all the programs at all times when the number of programs increases. As a possible measure, users' preferences can be summarized in some way and programs can be selected based on the result of summarization. A problem is, however, how to summarize users' requests and reflect the requests in selection of broadcast programs.

An object of the present invention is to provide a technique that enables users' requests to be appropriately reflected in the selection of broadcast programs in a broadcast system which selectively broadcast programs.

To attain the object, a broadcast system according to an aspect of the present invention is a broadcast system that assigns a communication channel to a program and broadcasts data for the program to terminals, the system including:

a broadcast management device that calculates as a score a measure of viewing requests from users of the terminals for a program that is being actually broadcast on the communication channel and a program that is not being actually broadcast but can be broadcast, and that updates the program that is to be actually broadcast on the communication channel by selecting from the program that is being actually broadcast on the communication channel and a program that is not actually being broadcast but can be broadcast based on the score calculated; and

a communication access network device that, upon the program to be actually broadcast on the communication channel being updated by the broadcast management device, broadcasts on the communication channel data for the program selected as the program to be broadcast.

A broadcast management device according to an aspect of the invention is a broadcast management device that manages programs to broadcast in a broadcast system which assigns a communication channel to a program and broadcasts data for the program to terminals, the broadcast management device including:

score calculating means for calculating as a score a measure of viewing requests from users of the terminals for a program that is actually being broadcast on the communication channel and a program that is not being actually broadcast but can be broadcast; and

determination means for updating the program to be actually broadcast on the communication channel by selecting from among the program that is being actually broadcast on the communication channel and the program that is not actually being broadcast but can be broadcast based on the score calculated by the score calculating means.

A broadcast method according to an aspect of the invention is a broadcast method for assigning a communication channel to a program and broadcasting data for the program to terminals, the method including the steps of:

calculating as a score a measure of viewing requests from users of the terminals for a program that is actually being broadcast on the communication channel and a program that is not being actually broadcast but can be broadcast;

updating the program that is to be actually broadcast on the communication channel by selecting from among the program that is being actually broadcast on the communication channel and the program that is not actually being broadcast but can be broadcast based on the score calculated; and

upon updating the program to be actually broadcast on the communication channel, broadcasting on the communication channel data for the program selected as the programs to be broadcast.

BEST MODE FOR CARRYING OUT THE INVENTION

An exemplary embodiment for implementing the invention will be described in detail with reference to the drawings.

FIG. 1is a block diagram showing a configuration of a broadcast system according to the exemplary embodiment. Referring toFIG. 1, the broadcast system includes base station devices11, gateway device12, broadcast device13, and broadcast management device14. Base station devices11and gateway device12form wireless access network16. Base station devices11transmit and receive data to/from wireless terminals15on wireless channels.

The broadcast system of the present exemplary embodiment supports bi-directional point-to-point communication typified by voice calls as well as broadcast-type communication for broadcasting program data to multiple wireless terminals15from base station device11. Broadcast device13and broadcast management device14are devices for realizing broadcast of programs.

Broadcast device13outputs program data. Data output from broadcast device13is sent to, for example, base station devices11by way of a network not shown and gateway device12. Program data is broadcast from base station devices11to wireless terminals15on wireless channels, but because the number of wireless channels between base station devices11and wireless terminals15is limited, wireless channels may not be assigned to all programs.

Wireless terminal15is a device that sends and receives data via base station device11to realize communication desired by a user. As for programs, wireless terminal15is capable of selecting a program desired by the user from multiple programs broadcast from base station device11on wireless channels and receiving data for that program. The user thus can view the desired program. Wireless terminal15also sends to broadcast management device14via base station device11a viewing request message that contains request information indicating a program the user watches or a program the user wants to watch which is selected from programs broadcast on wireless channels from base station device11and from programs that are not being actually broadcast but can be broadcast.

A viewing request message may be sent when the user performs an operation for starting or terminating viewing of a program, or when the user performs an operation for changing the program he is watching, for example. A viewing request message may also be sent when wireless terminal15has entered a coverage area of a certain base station device11during viewing of a program, or when wireless terminal15has exited the area. Or as another example, a viewing request massage may be sent at certain time intervals.

Broadcast management device14selects programs that are to be actually broadcast on wireless channels from programs output from multiple broadcast devices13. Programs output from broadcast device13include programs that are actually being broadcast on wireless channels and programs that are not currently being broadcast but can be broadcast. A result of selection made on broadcast management device14is provided to base station device11via a network not shown and gateway device12.

To select programs to broadcast, broadcast management device14always manages programs being output from broadcast device13, and also calculates as a score how much requests for viewing are made for each program based on request information provided by wireless terminals15in viewing request messages. The viewing request may also contain an indication of how much views there are for programs that are currently broadcast. Broadcast management device14then determines programs to be broadcast according to each of the scores of programs.

Specifically, broadcast management device14may select a number of programs that can be broadcast in descending order of score, for example. If programs determined based on scores differ from programs currently being broadcast, programs to be broadcast are changed.

Also, because too frequent changing of broadcast programs based on simple comparison of scores would conversely cause inconvenience to users, protection for slowing down the frequency of change in broadcast programs may be effected. For example, broadcast programs may be changed when the score of a program that is not being broadcast has exceeded the score of a program currently being broadcast plus a predetermined protection value. Alternatively, broadcast programs may be changed when the score of a program has been continuously satisfying a condition for changing programs for a predetermined protection time period or longer.

Gateway device12is a gateway for connecting each base station device11to a network not shown.

Base station device11is a device that sends and receives data to/from wireless terminal15through a wireless channel. By covering a communication area with cells of multiple base station devices11as illustrated inFIG. 2, communication by wireless terminal15at various places is enabled. As for broadcast programs, base station device11broadcasts data for programs selected by broadcast management device14on a wireless channel.

Gateway device12may manage assignment of wireless channels of base station devices11and assign wireless channels to broadcast programs from broadcast device13according to decision by broadcast management device14. In that case, base station device11can broadcast program data on wireless channels according to assignment by gateway device12.

FIG. 3is a flowchart illustrating a broadcast program update process performed by the broadcast system according to the present exemplary embodiment. Referring toFIG. 3, broadcast management device14of the broadcast system calculates the score of each program based on request information provided by wireless terminals15(step101).

FIG. 4shows a table illustrating an example of the result of calculating each of the scores of programs. In the example ofFIG. 4, four programs on CH1to CH4are output from broadcast device13. CH1is broadcasting a baseball game and has a score of 20. Broadcast on CH2is a soccer game and has a score of 10. Broadcast on CH3is a tennis match and has a score of 8. Broadcast on CH4is a wrestling match and has a score of 15.

Referring back toFIG. 3, broadcast management device14then determines programs to broadcast on wireless channels based on each of the scores of programs (step102). If there is a change of broadcast programs (YES at step103), broadcast management device14notifies gateway device12of the change and updates broadcast programs (step104). If there is no change of programs to broadcast (NO at step103), the process is then terminated. In the example ofFIG. 4, it is assumed that the number of programs that can be broadcast on wireless channels is two. The programs on CHs1and4are being broadcast and programs on CHs2and3are not. Because there has been no reversal of scores, programs to be broadcast are not changed.

FIG. 5is a block diagram showing a configuration of broadcast management device14of the present exemplary embodiment. Referring toFIG. 5, broadcast management device14includes program manager21, broadcast-number manager22, score calculator23, determination unit24, and notification unit25.

Program manager21manages information on programs that are output from broadcast device13(broadcast information). Broadcast information includes a program broadcast schedule, for example. From the information, the start or end time of each program can be found out.

Broadcast-number manager22manages the number of broadcast programs that can be assigned a wireless channel and that can be actually broadcast. The number of such broadcast programs may be either a fixed value or a value that varies depending on the assignment of wireless channels on base station device11.

Score calculator23calculates the score of each program currently output from broadcast device13. The score of each program is counted based on request information provided by wireless terminals15.

For a program that is being broadcast, actual viewing thereof is regarded as a viewing request, for example: the score of the program may be incremented by one when a user has started to view the program or when wireless terminal15on which the program is being viewed has entered an area. Likewise, the score of the program may be decremented by one when a user has finished viewing the program or when wireless terminal15on which the program is being viewed has gone outside the area, for example.

For a program that is not being broadcast, its score may be incremented by one when a user makes an operation for requesting viewing of the program, for example. Likewise, the score of the program may be decremented by one when a user who has requested viewing of the program has cancelled his viewing request or requests viewing of another program.

Determination unit24selects programs equal to the number of broadcast programs that has been determined under management of broadcast-number manager22from among programs managed by program manager21, based on scores calculated by score calculator23. Selection of broadcast programs may be based on simple comparison of scores or may be protected by applying a protection number for scores or a protection time regarding timing of program change.

Notification unit25notifies base station device11or gateway device12of a change of programs to be broadcast when such a change has been determined by determination unit24.

FIG. 6is diagram for illustrating how each of scores of programs calculated by score calculator23varies depending on the state of wireless terminal15.

Wireless terminal15can be in a state in which a program is being viewed thereon and a state in which no program is being viewed, and in each of the two states, a state in which a program is being requested and a state in which no program is being requested. For simplicity, these states will be referred as follows: a state in which a program is being viewed will be called “viewing” state and a state in which no program is being viewed will be called “non-viewing” state. A state in which another program is being requested will be called “requesting” state and a state in which no other program is being requested will be called “non-requesting” state.

And combinations of these states will be called as follows. A state in which no program is being viewed and no program is being requested will be called “non-viewing and non-requesting” state; a state in which no program is being viewed but a program is being requested will be called “non-viewing and requesting” state; a state in which a program is being viewed and no other program is being requested will be called “viewing and non-requesting” state; and a state in which a program is being viewed but another program is being requested will be called “viewing and requesting” state.

When there is a change in the state of wireless terminal15, the score of program(s) changes. Also, when wireless terminal15in any of such states moves between areas, program scores in the source and destination areas change. InFIG. 6, arrows represent changes in state, and score variation as a result of a state change is indicated near the arrows. “R” and “R′” represent a program currently being viewed or requested, “+” denotes an increment of a score, and “−” denotes a decrement of a score.

For describing scores in these states, the state of wireless terminal15present in a particular area will be discussed first.

A score is not counted when wireless terminal15in “non-viewing and non-requesting” state.

When wireless terminal15transitions from non-viewing and non-requesting to viewing and non-requesting state, the score of the program which is now being viewed is incremented by one. This corresponds to when a user has started to watch a program.

When wireless-terminal15transitions from viewing and non-requesting state to non-viewing and non-requesting state, the score of the program that was being viewed is decremented by one. This represents a case where the user stops viewing a program without requesting any other program.

When wireless terminal15transitions from non-viewing and non-requesting to non-viewing and requesting state, the score of the requested program is incremented by one. This is caused by the user seeing a terminal indication described below and starting to request a program he wants to watch.

When wireless terminal15transitions from non-viewing and requesting to non-viewing and non-requesting state, the score of the program that was being requested is decremented by one. This occurs as a result of the user giving up viewing a program he has wanted to watch.

When wireless terminal15transitions from viewing and non-requesting to viewing and requesting state, the score of the program that has been viewed is decremented by one and the score of the program being requested is incremented by one. This is caused by the user wanting to view a different program. In this case, the score of the program that is being viewed is decremented on the assumption that the program the user is now watching is watched expediently and is not really desired by the user.

When wireless terminal15transitions from viewing and requesting to a viewing and non-requesting state, the score of the program that has been viewed is incremented by one and the score of the program that was being requested is decremented by one. This corresponds to when the user wanted to watch a different program from the current one but found that the current program was the program he wants to watch.

When wireless terminal15transitions from viewing and requesting to a non-viewing and requesting state, neither the score of the program that was being viewed nor the score of the program that has been requested change. This corresponds to a case where the user was watching a program that the user did not desire and stopped viewing the program because a program the user was requesting did not start. In this case, the scores do not change because the program requested by the user remains unchanged.

When wireless terminal15transitions from non-viewing and requesting to a viewing and non-requesting state, the score of the program that was being requested is equivalent to the score of the program that is currently being viewed and there is no change in score. This is caused by transition from a non-viewing to a viewing state as a result of the user seeing a terminal indication described below to learn that the program the user requested has become available for viewing or by an internal mechanism inside wireless terminal15detecting that the requested program is now available for viewing. In this case, there is no change in score because the program the user wants to watch remains unchanged.

When wireless terminal15changes the program it requests while in a viewing and requesting state, the score of the program for which a request has been canceled is decremented by one and the score of the program newly requested is incremented by one.

When wireless terminal15changes the program it requests while in a non-viewing and requesting state, the score of the program for which a request has been canceled is decremented by one and the score of the program newly requested is incremented by one.

Now, variation in scores that occurs when wireless terminal15moves between areas will be described.FIG. 7is a diagram illustrating how scores change when wireless terminal15moves between areas. InFIG. 7, arrows represent state transitions caused by wireless terminal15moving between areas.

Descriptions will be given on the movement of wireless terminal15from one area to another area in one of the two viewing states and in one of the two requesting states. Program scores in each of the source and destination areas are independent of each other. When wireless terminal15moves, the score of a program that has been requested in the source area is decremented as a result of wireless terminal15leaving the area. In the destination area, in response to the entry of wireless terminal15, the score of a program that was being requested in the source area may be incremented, or when the program is not defined in the destination area, the score of the program may not be incremented. It is assumed that wireless terminal15moves from area1to area2, and the state of wireless terminal15in area1will be described for four states, i.e., non-viewing and non-requesting, non-viewing and requesting, viewing and non-requesting, and viewing and requesting another program.

When wireless terminal15that is non-viewing and non-requesting in area1moves to area2, there is no change in program scores.

When wireless terminal15that is in non-viewing and requesting state in area1moves to area2, wireless terminal15can transition to one of two states, that is, a non-viewing and non-requesting state and a non-viewing and requesting state. A reason for transitioning to a non-viewing and non-requesting state in area2is that the program that wireless terminal15was requesting in area1is not able to broadcast in area2. In this case, the score of the program that was being requested in area1is decremented and the score of no program is incremented in area2. When wireless terminal15transitions to non-viewing and requesting state in area2as in area1, the score of the program that was being requested in area1is decremented and the score of the same program is incremented in area2.

When wireless terminal15that is in a viewing and non-requesting state in area1moves into area2, wireless terminal15can transition to one of three states: non-viewing and non-requesting, non-viewing and requesting, and viewing and non-requesting states. A reason for transitioning to non-viewing and non-requesting state in area2is that the program that was being viewed in area1cannot be requested in area2because the program is not being broadcast or is not able to be broadcast in area2. In this case, the score of the program that was being viewed in area1is decremented and no program score is incremented in area2. A reason for transitioning to a non-viewing and requesting state in area2is that the program that was being viewed in area1is not currently broadcast in area2but is not able to be broadcast and thus can be requested. In this case, the score of the program that was being viewed in area1is decremented and also incremented for the reason that the same program is requested in area2. A reason for transitioning to a viewing and non-requesting state in area2is that the same program as in area1can be viewed in area2. In this case, the score of the program that was being viewed in area1is decremented and the score of the same program is incremented in area2.

When a terminal that is in a viewing and requesting state in area1moves to area2, the terminal can transition to one of four states: non viewing and non-requesting, non-viewing and requesting, viewing and non-requesting, and viewing and requesting states. A reason for transitioning to a non-viewing and non-requesting state in area2is that the program that was being viewed in area1is not currently being broadcast or is not able to be broadcast in area2and thus cannot be requested. In this case, the score of the program that was being requested in area1is decremented and the score of no program is incremented in area2. A reason for transitioning to a non-viewing and requesting state in area2is that the program that was being viewed in area1is not currently being broadcast in area2but the program that was being requested in area1is able to be broadcast in area2and thus can be continued to be requested. In this case, the score of the program that was being requested in area1is decremented and then incremented as the same program is requested in area2. A reason for transitioning to a viewing and non-requesting state in area2is that the program that was being viewed in area1is currently being broadcast in area2but the program that was being requested is not able to be broadcast in area2. In this case, the score of the program that was being requested in area1is decremented, and the score of the currently viewed program is incremented in area2regarding that the program is requested. Another reason for transitioning to a viewing and non-requesting in area2is that the program that was being viewed in area1is not being broadcast in area2now but a program that was being requested is able to be broadcast in area2, so the user is encouraged to watch the program that the user has requested. In this case, the score of the program that was being requested in area1is decremented and the score of no program is incremented in area2.

As described above, the present exemplary embodiment calculates scores for multiple programs that represent how much the programs are viewed or how much viewing requests are made for the programs, and updates programs that are actually broadcast on wireless channels based on the scores. Therefore, limited wireless channels can be efficiently used and programs highly requested by users can be selected and broadcast.

In the broadcast system of the present exemplary embodiment, wireless terminals15may be notified of each of program scores calculated by broadcast management device14via wireless access network16as notice information. In that case, a result of calculation by score calculator23may be provided by notification unit25by broadcast, for example. By wireless terminal15indicating the status of individual programs on a screen based on the notice information, the user can learn the status of the program he is now watching or a program for which the user has made a viewing request. Status of a program may be information including its scheduled start and end of broadcast or the score of the program itself.

In the present exemplary embodiment, broadcast management device14is located outside wireless access network16and sends decisions made on device14to wireless access network16. However, this is not limitative. As another example, broadcast management device14may also be integrated into gateway device12or base station device11.

A more specific exemplary embodiment will be shown in the following.

The broadcast system according to the exemplary embodiment has such a configuration as shown inFIG. 1, and multiple base station devices11are positioned in the system as illustrated inFIG. 2.

In this exemplary embodiment, notice information provided by wireless terminal15includes a channel that the user is actually watching (a viewed channel) and a channel the user wants to watch (a requested channel).FIG. 8shows a format of a viewing request message sent from wireless terminal15. Referring toFIG. 8, a viewing request message is in a format that can indicate a viewed channel (Viewed CH) and a requested channel (Requested CH) as notice information together with a terminal ID (Identifier). In a viewing request message from wireless terminal15, the viewing and requesting status of programs by the user of wireless terminal15is indicated. The content of the viewing request message may be based on the following patterns, for example:(1) When the user is viewing a certain broadcast program and requesting the same program; Viewed CH=“viewed channel”, and Requested CH=“unspecified” or “viewed channel”.(2) When the user is viewing a certain broadcast program and requesting a different program; Viewed CH=“viewed channel” and Requested CH=“requested channel”.(3) When the user is neither viewing nor requesting a program; Viewed CH=“unspecified” and Requested CH=“unspecified”.(4) When the user is not viewing a program and requesting viewing of any program; Viewed CH=“unspecified” and Requested CH=“requested channel”.
FIG. 9shows an example of a signal sequence between a wireless terminal and a base station device performed when the user has updated the requested CH. The requested channel is updated when the user changes the requested channel or cancels a viewing request for a program, for example. Referring toFIG. 9, notification of viewed and requested channels is sent in response to a request operation on wireless terminal15performed by the user. This notification is sent in the viewing request message illustrated inFIG. 8.

When the user is currently viewing a broadcast program, the user may then request for a program different from the current one, or cancel the current request for a program, or request no program. When the user requests no program, the user can be considered to be requesting the program he is now watching.

FIG. 10is an example of a signal sequence between a wireless terminal and a base station device that takes place when a wireless terminal on which a broadcast program is being viewed enters the coverage area of a base station device. A similar sequence will be also performed when a wireless terminal that has not been viewing a broadcast program starts viewing a broadcast program. Referring toFIG. 10, upon entering the area, wireless terminals1to3send notification of their viewed and requested channels. Notification of viewed and requested channels is transferred in the viewing request message shown inFIG. 8.

When wireless terminal15enters the coverage area of base station device11from outside of the area, the channel of a program that is now being viewed on the terminal is reported as its viewed channel and the channel of a program that is currently being requested by the terminal is reported as its requested channel. Wireless terminal15automatically sends a viewing request message without requiring the user to perform an operation on wireless terminal15.

If a program that was not broadcast in the coverage area of base station device11in which wireless terminal15was previously positioned and which the user was requesting is broadcast in the coverage area of base station device11which wireless terminal15has newly entered, wireless terminal15may automatically change the viewed channel. Wireless terminal15may also indicate to the user that the program the user has requested is now available for viewing through display, sound output, or vibration. This allows the user to automatically start viewing a desired broadcast program without being aware of travel between base station devices11.

When the user of wireless terminal15who has not been viewing a program starts viewing a broadcast program, wireless terminal15transfers a message indicating viewed and requested channels as soon as or upon elapse of a certain time period after the user selects a program to receive and wireless terminal15starts receiving operations.

FIG. 11shows a signal sequence for collecting information on viewed and requested channels by the system requesting wireless terminals in the coverage area of the base station device to send such information. In this example, base station device11sends a simultaneous request message using a common channel which can be received by wireless terminals15, in response to which wireless terminals1to3send their respective viewed and requested channels to broadcast management device14via base station device11.

To avoid the occurrence of congestion on base station device11or broadcast management device14with messages from wireless terminals15, wireless terminals15in the coverage area of base station device11may be divided into some groups and a simultaneous request message may be sent to each of the groups at different times.

FIG. 12shows an illustrative program viewing and requesting states on each of the wireless terminals that are present in the coverage area of a base station device at a certain time. It is assumed here that programs on four channels1to4can be broadcast in the coverage area of base station device15and that programs actually being broadcast are channels1and4, and that programs channels2and3are not being broadcast.

For example, wireless terminals15having a terminal ID from 1 to 19 are watching channel1and not requesting any other channel. Wireless terminals15having a terminal ID from 20 to 22 are watching channel1and requesting channel2. This corresponds to a situation in which a user really wants to view channel2but is viewing channel1because channel2is not broadcast, for example. Wireless terminal15having a terminal ID of 26 is viewing channel1and requesting channel4. This represents a situation where the user actually wants to view channel4but is temporarily watching channel1, for example. Wireless terminals15having a terminal ID from 51 to 55 are not viewing any program and are requesting channel2.

FIG. 13is a schematic representation of the situation ofFIG. 12, where the four programs being able to be broadcast are indicated as boxes #1to #4. A solid-line box represents a program that is actually being broadcast and a broken-line box represents a program not in service. Programs #1and #4are being broadcast, and #2and #3are not.

The #1box shows that there are nineteen wireless terminals15that are viewing program #1and are not requesting other program. Also, three wireless terminals15are viewing the #1program and requesting the #2programs. Three wireless terminals15are viewing the #1program and requesting the #3program. One wireless terminal15is viewing the #1program and requesting the #4program.

Similarly, in the #4box, it can be seen that there are seventeen wireless terminals15that are viewing the #4program and are not requesting other programs. Two wireless terminals15are viewing the #4program and requesting the #2program. Three wireless terminals15are viewing the #4program and requesting the #3program. Two wireless terminals15are viewing the #4program and requesting the #1program.

Referring to the broken-line box in the center, there are five wireless terminals15that are viewing no program and requesting the #2program. Seven wireless terminals are viewing no program and requesting the #3program.

FIG. 14shows a situation after elapse of a certain time from the situation ofFIG. 13.

For example, in the #1box, there are nineteen wireless terminals15that are viewing the #1program and not requesting any other program, which remains unchanged from the situation ofFIG. 13. However, the number of wireless terminals15that are viewing the #1program and requesting the #2program has increased to five.

Similarly, in #4, wireless terminals15that are viewing the #4program and that are not requesting other program have decreased to thirteen. Also, wireless terminals15that are viewing the #4program and requesting the #2program have increased to four.

FIG. 15is a tabular representation of the situation shown inFIG. 13.FIG. 16is a table that re-sorts the table ofFIG. 15.

Referring toFIG. 16, the #1program is being viewed and requested on nineteen wireless terminals15. The #1program is requested by two wireless terminals15that are viewing the #4program.

The #2program is requested by three wireless terminals15viewing the #1program, two wireless terminals15viewing the #4program, and five wireless terminals15not viewing any program.

The #3program is requested by three wireless terminals15viewing the #1program, three wireless terminals15viewing the #4program, and seven wireless terminals15not viewing any program.

The #4program is being viewed and requested on seventeen wireless terminals15. The #4program is also requested by one wireless terminal15that is viewing the #1program.

FIG. 17is a tabular representation of the situation shown inFIG. 13.FIG. 18is a table that re-sorts the table ofFIG. 17.

Referring toFIG. 18, the #1program is being viewed and requested on nineteen wireless terminals15. The #1program is also requested by two wireless terminals15that are viewing the #4program.

The #2program is requested by five wireless terminals15viewing the #1program, four wireless terminals15viewing the #4program, and eight wireless terminals15not viewing any program.

The #3program is requested by three wireless terminals15viewing the #1program, three wireless terminals15viewing the #4program, and seven wireless terminals15not viewing any program.

The #4program is being viewed and requested on thirteen wireless terminals15. The #4program is also being requested by one wireless terminal15viewing the #1program.

In this exemplary embodiment, the score of each program is calculated according to Equation (1):
Score=(the number of views)+(the number of requests)−(the number of other-channel requests)  (1)

The number of views is the number of wireless terminals15that are actually viewing the program of interest. The number of requests is the number of wireless terminals15that are requesting the program. The number of other-channel requests is the number of wireless terminals15that are viewing the program and also requesting another program.

The score serves as an index to indicate which program is desired for viewing, whether actually watched by the users of wireless terminals15or not. By selecting programs based on the score, it is possible to select and broadcast programs that are truly requested.

FIG. 19is a diagram illustrating the process of calculating the score of each program in the situation ofFIG. 13(andFIGS. 15,16).FIG. 20is a diagram illustrating the process of calculating the score of each program in the situation ofFIG. 14(andFIGS. 17,18).

In the situation ofFIG. 13, for example, the number of views is the sum of the numbers of reports inFIG. 15in the column direction. The number of requests is the number of reports that are requesting the program of interest minus the number of reports from wireless terminals15that are viewing that program, which are shown inFIG. 16. The number of other-channel requests is the number of reports requesting other programs among reports from wireless terminals15that are viewing the program, which is shown inFIG. 15.

The score calculated with Equation (1) indicates users of how many wireless terminals15request each program for viewing. Broadcast management device14selects programs to broadcast on wireless channels starting with a program that is requested by the most users for viewing.

More specifically, suppose that viewing and requesting states at a certain time are analyzed as shown inFIGS. 15 and 16, and scores are calculated as illustrated inFIG. 19. At this point, the scores of the #1, #2, #3and #4programs are 21, 10, 13, and 18, respectively.

Then, when a certain time has elapsed, the situation is analyzed as illustrated inFIGS. 17,18and scores are calculated as shown inFIG. 20. At this point, the score of the #2program has increased to 17 and the score of the #4program has decreased to 14. As a result, the scores of the #2and #4programs have been reversed: now the #2is getting more viewing requests than the #4program. Broadcast management device14then makes a switch so as to stop broadcasting the #4program and start broadcasting the #2program instead.

FIG. 21shows an example of notice information provided to wireless terminals. Notice information contains channel number (Ch_No.), program title (Program_Name), broadcast status (Status), score (Score), and broadcast switching time (Action_Time), for each program.

In the notice information shown in the figure, the same scores as those ofFIG. 19which are calculated for the situation shown inFIG. 13are described. Specifically, a baseball game is being broadcast on Ch#1and the score of the program is 21. Ch#2is broadcasting a soccer game, but the program is not being broadcast on a wireless channel and has a score of 10. Ch#3is broadcasting a tennis match, but the program is not being broadcast on a wireless channel and has a score of 13. On Ch#4, wrestling is being broadcast and the score of the program is 18.

FIG. 22shows an example of notice information that is sent to wireless terminals upon elapse of a certain time from the situation ofFIG. 21.

In the notice information ofFIG. 22, the same scores as those shown inFIG. 20which are calculated for the situation ofFIG. 14are described. Specifically, a baseball game is being broadcast on Ch#1and the program has a score of 21. Ch#2is soccer, but the program is not being broadcast and the score of the program is 17. Ch#3is tennis, but the program is not being broadcast and the score of the program is 13. On Ch#4, a wrestling match is being broadcast and the score of the program is 14.

At this point, the score of Ch#2(17) which is not being broadcast is greater than the score of Ch#4(14) which is being broadcast. Accordingly, broadcast management device14has decided to switch programs. The notice information ofFIG. 22indicates the amount of time before the change in Action_Time to give an advance notice of the change. In the example ofFIG. 22, the amount of time before switching is 120 seconds.

In this exemplary embodiment, it is assumed that wireless terminal15has functions to specify a program currently being broadcast that the user wants to watch or a program that is not being broadcast but the user wants to watch such as by scrolling through icons on a screen and notify broadcast management device14of the program.

FIG. 23shows an example of a screen display on a wireless terminal that has received the notice information ofFIG. 21. The screen of the figure displays channel number (Ch_No.), current broadcast status (Status), program title (Program_Name), score (Score), and requested program indication (Req), for each program. A program with “R” indicated in a requested program indication is a program requested by the user of wireless terminal15. In the example ofFIG. 23, Ch#2is requested.

FIG. 24shows an example of a screen display on a wireless terminal that has received the notice information ofFIG. 22. In the screen ofFIG. 24, the same items as inFIG. 23are displayed. The user is still requesting Ch#2at this point, “R” being indicated with Ch#2. Also, the broadcast status of Ch#2is indicated as “Beginning”. This means broadcast on the wireless channel for Ch#2is being started. The broadcast status of Ch#4is indicated as “Completing”. This means broadcast on Ch#4is being terminated. By seeing the indication, the user can recognize that broadcast of a program that the user is requesting is now starting. Also, a user watching a program on Ch#4recognizes that broadcast on Ch#4he is watching is going to end.

FIG. 25illustrates a switch of programs broadcast on wireless channels. In the figure, the vertical axis represents score and the horizontal axis represents time. Broken lines indicate scores of programs. At time t0, the score of program1is greater than the score of program2. However, at time t1, the score of program2becomes equal to that of program1, and from then on the score of program2exceeds the score of program1. At first, program1is broadcast and program2is not, and from time t1on, program2is broadcast in place of program1.

In selection of programs to broadcast on wireless channels, protection for preventing frequent switch may be applied.

FIG. 26is a diagram illustrating switching of programs with score protection applied. Referring toFIG. 26, change in scores of programs1and2over time is the same as inFIG. 25. In this example, however, switching of programs is effected at the time when the score of program2has exceeded the score of program1by a protection value (a difference vx) (t2), rather than at the time when the scores of programs1and2have been reversed (t1). The difference vx may be arbitrarily set.

FIG. 27is a diagram illustrating switching of programs with time protection applied. Referring toFIG. 27, change in scores of programs1and2over time is the same as inFIG. 25. In this example, however, the switching of programs takes place at the time when the score of program2has been continuously greater than the score of program1for a protection time (a time period tx) (t2) rather than when the scores of the programs1and2have been reversed (t1). This can prevent too frequent switching and also allow notification of a switch of programs to the user so that the user can anticipate it. Time period tx may be arbitrarily defined.

FIG. 28is a diagram illustrating switching of programs with both score protection and time protection applied. Referring toFIG. 28, at time t1, the score of program2exceeds the score of program1by a difference vx. However, switching of programs is not effected at this point. Rather, programs are switched at a time when the score of program2is greater than the score of program1by the difference vx or greater for the time period tx (t2).

FIG. 29is a diagram illustrating a case where switching of programs does not occur as a result of applying time protection. Suppose that such time protection as described inFIG. 27is applied to switching of programs. Referring toFIG. 29, the scores of programs1and2are reversed at time t1. But at time t2, which is a time point before elapse of time period tx from time t1, the scores of programs1and2are reversed again. Thus, programs broadcast on wireless channels are not changed.

While the exemplary embodiments described so far illustrate a broadcast system utilizing wireless lines, the present invention is not limited to such a configuration. The invention is also applicable to a broadcast system based on wired lines. In addition, a communication channel used for transmitting broadcast content data and notice information including each of the program scores does not have to be identical with a communication channel used for transmitting requests from terminals and terminal-specific information containing responses to the requests. Wired and wireless communication channels can be used as appropriate. To be specific, communication channels can be selectively used according to the following patterns:

(1) Use wireless channels for both transfer of broadcast content and notice information, and transfer of terminal-specific information;

(2) Use wireless channels for transfer of broadcast content and notice information, and wired channels for transfer of terminal-specific information;

(3) Use wired channels for transfer of broadcast content and notice information, and wired channels for transfer of terminal-specific information; or

(4) Use wired channels for transfer of broadcast content and notice information, and wireless channels for transfer of terminal-specific information.

Because program content data and notice information distributed by broadcast device13both have high simultaneity, they are preferably transferred on channels of the same type. On the other hand, because requests from terminals and responses to the requests are more discrete, they do not have to be transferred on channels of the same type as program content.

In the case of (2), such a system is conceivable where terrestrial digital broadcasting is received on terminals (or televisions) installed in homes and viewers' requests are summarized to be reflected in the selection of broadcast programs. For example, inFIG. 1, program content data and notice information distributed by broadcast device13may be transmitted on wireless channels and request information to be sent to broadcast management device14may be transmitted on wired channels of a wired network (not shown).

FIG. 30illustrates signal transfer with wireless channels used for both transfer of broadcast content and notice information, and transfer of terminal-specific information, which corresponds to (1). In the figure, a solid-line arrow represents signal transfer on a wired channel, and a broken-line arrow represents signal transfer on a wireless channel. In this example, a wireless channel is used as a broadcast/notice information channel (a common channel) for transferring broadcast content and notice information, which have high simultaneity. A wireless channel is also used for a terminal-specific information transfer channel (an individual channel) for transferring viewing request messages and responses to the messages, which are more discrete.

FIG. 31illustrates signal transfer using wireless channels for transfer of broadcast content and notice information, and wired channels for transfer of terminal-specific information, which corresponds to (2) above. Again, a solid-line arrow represents signal transfer on a wired channel and a broken-line arrow represents signal transfer on a wireless channel. In this example, a wireless channel is used as broadcast/notice information channel for transferring broadcast content and notice information, which have high simultaneity. Meanwhile, a wired channel is also used as a terminal-specific information transfer channel for transferring viewing request messages and responses to the messages, which are more discrete.

In addition, terminals used with the present invention are not limited to mobile terminals, but may be fixedly-installed terminals (fixed terminals), whether wired or wireless. In the case of a fixed terminal, entry to an area shown inFIG. 8is not relevant, but similar operations to the sequence shown inFIG. 8take place upon power-up of the terminal, which is relevant to both mobile and fixed terminals.

While the present invention has been described with reference to the exemplary embodiments thereof, the invention is not limited to the embodiments. Rather, various modifications comprehensible to those skilled in the art may be made to the constitution or details of the invention as defined in the claims without departing from the scope of the invention.