JP7193859B2 - Base station and communication method - Google Patents

Description

It relates to a base station for communication.

Conventionally, a base station that broadcasts transmission data to a plurality of terminals is known (see Patent Document 1, for example). Note that the term “broadcast transmission” is a broad term that includes both concepts of broadcast transmission in a narrow sense and multicast transmission in a narrow sense. In addition, the term "broadcast transmission" simply refers to broadcasting in a broad sense.

JP 2014-049834 A

Conventionally, when a power-saving terminal capable of receiving data only for a predetermined period is connected to a base station that broadcasts data for transmission, the power-saving terminal receives data from the base station. Broadcast transmission is performed in accordance with the timing at which data can be received (that is, the time period during which data can be received). For this reason, terminals other than power-saving terminals connected to the base station are delayed in receiving transmission data transmitted by broadcast transmission, compared to when no power-saving terminals are connected to the base station. I can put it away.

Therefore, the present invention provides data for transmission to be transmitted by broadcast transmission to terminals other than the power-saving terminal even when the power-saving terminal is connected to the base station. To provide a base station or the like capable of receiving data for transmission without delay and allowing a power-saving terminal to receive the data for transmission.

In order to solve the above problems, a base station according to one aspect of the present invention is a base station that communicates with a plurality of terminals including one or more power-saving terminals, the acquisition unit acquiring transmission data; a transmission unit that performs broadcast transmission of the transmission data acquired by the acquisition unit, wherein the transmission unit promptly broadcasts the transmission data acquired by the acquisition unit to the plurality of terminals; The one or more power-saving terminals retransmit the transmission data acquired by the acquisition unit at a timing at which data reception becomes possible.

The base station can perform broadcast transmission of data for transmission regardless of the timing at which power-saving terminals become receivable. As a result, according to the base station, even when a power-saving terminal is connected to the base station, the power-saving terminal can transmit data for transmission to terminals other than the power-saving terminal by broadcast transmission to the base station. It can be received without delay compared to the case of no connection. On the other hand, the base station retransmits the transmission data at the timing when the power saving terminal becomes ready to receive the data. Thereby, according to the base station, the power saving terminal can also receive the data for transmission. As described above, according to the base station, even when a power-saving terminal is connected to the base station, the power-saving terminal transmits data for transmission to terminals other than the power-saving terminal by broadcast transmission. As compared with the case where the is not connected, the power-saving terminal can be made to receive the transmission data without delay.

Further, a beacon transmission unit that periodically transmits a beacon is provided, and the one or more power saving terminals can receive data at the timing when the beacon is transmitted from the beacon transmission unit, and the transmission unit may perform the retransmission at the timing when the beacon transmitting unit transmits the beacon.

Thereby, the base station can use the beacon to cause the power saving terminal to receive the data for transmission.

Further, the apparatus further comprises a receiving unit for receiving a notification signal indicating a timing at which data can be received, which is transmitted from each of the one or more power-saving terminals, wherein the transmitting unit receives the signal received by the receiving unit. The retransmission may be performed at the timing indicated by the notification signal when the data can be received.

Thereby, the base station can use the notification signal to cause the power-saving terminal to receive the transmission data.

Further, the transmission unit may perform the retransmission by broadcast transmission.

Thereby, the base station can make the power-saving terminal receive data for transmission using broadcast transmission.

Further, the transmission unit may set a transmission sequence number assigned to the transmission data in the retransmission to be the same as a transmission sequence number assigned to the transmission data in broadcast transmission performed prior to the retransmission. .

As a result, the terminal can relatively easily determine that it has redundantly received the data for transmission.

Further, the transmission unit may perform the retransmission by unicast transmission.

Thereby, the base station can make the power-saving terminal receive data for transmission using unicast transmission.

Further, the one or more power-saving terminals are a plurality of power-saving terminals, and the transmitting unit transmits the retransmission by the unicast transmission to the plurality of power-saving terminals according to a predetermined sequence. A polling method may be used.

Thereby, the base station can cause a plurality of power-saving terminals to receive transmission data.

Further, the base station and the plurality of terminals perform communication conforming to the IEEE802.11 standard, the one or more power saving terminals are terminals that enter a power saving mode in the IEEE802.11 standard, and the beacon transmission is performed. The unit may transmit said beacon periodically at the DTIM interval in the IEEE 802.11 standard.

As a result, the base station can be used in a system conforming to the IEEE802.11 standard.

In order to solve the above problems, a communication method according to one aspect of the present invention is a communication method performed by a base station communicating with a plurality of terminals including one or more power saving terminals, the method comprising: obtaining data for transmission; a transmission step of promptly broadcasting the transmission data acquired in the acquisition step; and retransmitting the transmission data.

The above communication method enables broadcast transmission of transmission data regardless of the timing at which the power-saving terminal becomes ready for reception. Thus, according to the above communication method, even when a power-saving terminal is connected to a base station, the power-saving terminal transmits data for transmission to terminals other than the power-saving terminal by broadcast transmission to the base station. It can be received without delay compared to the case of no connection. On the other hand, in the above communication method, the power-saving terminal retransmits the data for transmission at the timing when the data can be received. Thus, according to the above communication method, the power saving terminal can also receive the transmission data. As described above, according to the above communication method, even when a power-saving terminal is connected to a base station, transmission data to be transmitted to terminals other than the power-saving terminal by broadcast transmission can be sent to the base station by the power-saving terminal. As compared with the case where the is not connected, the power-saving terminal can be made to receive the transmission data without delay.

The present invention can be realized not only as an apparatus, but also as a method in which processing means constituting the apparatus are used as steps, as a program for causing a computer to execute the steps, or as a computer-readable program in which the program is recorded. It can also be implemented as a recording medium such as a CD-ROM, or as information, data, or signals indicating the program. These programs, information, data and signals may then be distributed over a communication network such as the Internet.

According to the base station and the like of the present invention, even when a power-saving terminal is connected to the base station, transmission data to be transmitted by broadcast transmission to terminals other than the power-saving terminal can be sent to the base station in a power-saving manner. The data can be received without delay compared to the case where the terminal is not connected, and the power-saving terminal can also receive the data for transmission.

FIG. 1 is a configuration diagram of a communication system according to Embodiment 1. FIG. 2 is a configuration diagram of a base station according to Embodiment 1. FIG. FIG. 3 is a flowchart of the first transmission process. FIG. 4 is a flowchart of reception processing. 5 is a timing chart showing a specific example of communication between the base station and the terminal according to Embodiment 1. FIG. FIG. 6 is a configuration diagram of a base station according to Embodiment 2. In FIG. FIG. 7 is a flowchart of the second transmission process. FIG. 8 is a timing chart showing a specific example of communication between a base station and terminals according to the second embodiment.

Hereinafter, embodiments will be specifically described with reference to the drawings.

All of the embodiments described below represent preferred specific examples of the present invention. Numerical values, shapes, materials, components, arrangement positions and connection forms of components, steps, order of steps, and the like shown in the following embodiments are examples and are not intended to limit the present invention.

(Embodiment 1)
A communication system in which a base station acquires data from a server and broadcasts the acquired data to a plurality of terminals will be described below.

FIG. 1 is a configuration diagram of a communication system 1 according to Embodiment 1. As shown in FIG.

As shown in FIG. 1, the communication system 1 includes a base station 10, non-power saving terminals 21a to 21c, a power saving terminal 22a, a server 30, and a network . Hereinafter, the non-power-saving terminals 21a to 21c may be simply referred to as the non-power-saving terminals 21 when there is no need to distinguish between them. The non-power-saving terminals 21a to 21c and the power-saving terminal 22 may be simply referred to as the terminal 20 when there is no need to distinguish between them. Also, the power saving terminal 22 a may be simply referred to as the power saving terminal 22 .

A terminal 20 performs wireless communication with the base station 10 . Radio communication between the base station 10 and the terminal 20 includes broadcast transmission by the base station 10 and unicast transmission by the base station 10 . The wireless communication performed between the base station 10 and the terminal 20 may be communication based on the IEEE802.11 standard, for example. However, this is just an example, and the wireless communication performed between the base station 10 and the terminal 20 is not limited to communication conforming to the IEEE802.11 standard.

The terminals 20 include one or more power-saving terminals 22 and one or more non-power-saving terminals 21 .

In order to reduce its own power consumption, the power-saving terminal 22 operates in a power-saving mode in which wireless communication with external devices cannot be performed, and a non-power-saving mode in which wireless communication with external devices can be performed. operates by switching between However, the power saving terminal 22 can receive a beacon (described later) transmitted from the base station 10 even in the power saving mode. When the power-saving terminal 22 receives a beacon transmitted from the base station 10 in the power-saving mode, the power-saving terminal 22 switches its operation mode from the power-saving mode to the non-power-saving mode. Then, when the predetermined condition is satisfied, the operation mode of itself is switched to the power saving mode again. Here, the predetermined condition may be, for example, a condition that a predetermined period of time has elapsed since the beacon was received, or a predetermined process (for example, receiving broadcast transmission or unicast transmission from the base station 10). process) is completed.

Further, when the power saving terminal 22 is in the power saving mode, the power saving terminal 22 changes its own operation mode from the power saving mode to the non-power saving mode, for example, upon receiving a notification from a built-in timer or receiving an operation by the user. can be switched to In this way, when the operation mode of itself is switched from the power saving mode to the non-power saving mode voluntarily without synchronizing with the beacon transmitted from the base station 10, the power saving terminal 22 switches itself to the non-power saving mode. A notification signal indicating the timing at which wireless communication becomes possible by switching the operation mode from the power saving mode to the non-power saving mode (that is, the notification signal indicating the timing at which data reception becomes possible) is sent to the base station 10. Send to The power saving terminal 22 may be, for example, a terminal that enters a power saving mode according to the IEEE802.11 standard. However, this is just an example, and the power saving terminal 22 is not limited to a terminal that enters the power saving mode according to the IEEE802.11 standard.

The non-power-saving terminal 21 is a terminal that always operates in the non-power-saving mode. That is, the non-power-saving terminal 21 is a terminal that does not operate in the power-saving mode.

A network 40 communicably connects a plurality of devices. The plurality of devices includes server 30 and base station 10 . In FIG. 1, the network 40 is illustrated as if it were a wired network that connects a plurality of devices so as to be able to communicate with each other through wires, but the network 40 is not necessarily limited to a wired network. For example, it may be a wireless network.

The server 30 stores data that the base station 10 transmits to the terminal 20 . The data stored by the server 30 may be audio data in an audio broadcast program, for example.

The base station 10 wirelessly communicates with the terminal 20 .

FIG. 2 is a configuration diagram of the base station 10. As shown in FIG.

As shown in FIG. 2, the base station 10 includes an acquisition unit 11, a transmission unit 12, a beacon transmission unit 13, and a reception unit .

The acquisition unit 11 acquires transmission data to be transmitted to the terminal 20 from the server 30 via the network 40 . Then, the acquired data for transmission is temporarily stored.

The transmission unit 12 broadcasts the transmission data acquired by the acquisition unit 11 . Further, the transmission unit 12 retransmits the transmission data acquired by the acquisition unit 11 at the timing when the power saving terminal 22 becomes ready to receive data. At this time, the transmission unit 12 retransmits the transmission data by broadcast transmission. The transmission data retransmitted by the transmission unit 12 is the transmission data acquired by the acquisition unit 11 and temporarily stored. For example, when the transmitting unit 12 retransmits the transmitting data, the acquiring unit 11 may discard the temporarily stored transmitting data.

As described above, when the power saving terminal 22 receives a beacon transmitted from the base station 10, it switches its operation mode from the power saving mode to the non-power saving mode. For this reason, the transmission unit 12 retransmits the transmission data at the timing when the beacon transmission unit 13 (to be described later) transmits a beacon. Resend credit data. On the other hand, as described above, when the power saving terminal 22 voluntarily switches its operation mode from the power saving mode to the non-power saving mode without synchronizing with the beacon transmitted from the base station 10, , to send notification signals. In this case, the transmission unit 12 retransmits the data for transmission at the timing indicated by the notification signal from the power saving terminal 22 when the data can be received, so that the power saving terminal 22 can receive the data. The data for transmission can be received at the timing when it becomes possible.

When retransmitting the transmission data, the transmission unit 12 sets the transmission sequence number to be assigned to the transmission data to be the same as the sequence number to be assigned to the transmission data in the broadcast transmission performed prior to retransmission. This is to avoid duplicate reception by the terminal 20 that has already received the data, and the details will be described later.

The beacon transmission unit 13 periodically transmits a beacon containing information necessary for wireless communication. The beacon transmission unit 13 may transmit a beacon periodically at, for example, DTIM (Delivery Traffic Indication Message) intervals in the IEEE802.11 standard. However, this is just an example, and the beacon transmission unit 13 does not necessarily need to periodically transmit a beacon at the DTIM interval in the IEEE802.11 standard.

The receiving unit 14 receives the notification signal transmitted from the power saving terminal 22 .

The operation performed by the communication system 1 having the above configuration will be described below.

In the communication system 1, the base station 10 performs a first transmission process for transmitting transmission data, and a non-power saving terminal 21 and a power saving terminal 22 in a non power saving mode (hereinafter, these terminals are referred to as "non The terminal 20 operating in the power saving mode (also referred to as "terminal 20") performs reception processing for receiving transmission data. Hereinafter, these first transmission processing and reception processing will be described in order with reference to the drawings.

FIG. 3 is a flowchart of the first transmission process.

The first transmission process is started, for example, when transmission data is transmitted from the server 30 to the base station 10 via the network 40 according to an instruction from a user who uses the server 30 .

When the transmission data is transmitted from the server 30, the acquisition unit 11 acquires the transmission data (step S100).

When the transmission data is obtained, the transmission unit 12 promptly broadcasts the transmission data (step S110).

When the transmission data is broadcast, the transmission unit 12 waits until the power saving terminal 22 can receive data (step S120: repeats No). More specifically, the transmitting unit 12 transmits the beacon at the earlier of the timing at which the beacon transmitting unit 13 transmits the beacon and the timing at which the receiving unit 14 receives the notification signal transmitted from the power saving terminal 22. wait until

When the power-saving terminal 22 becomes ready to receive data (step S120: Yes), the transmission unit 12 sets the transmission sequence number assigned to the transmission data to the transmission sequence number in the broadcast transmission performed prior to retransmission. The sequence number is set to be the same as the sequence number assigned to the data (step S130), and the transmission data is retransmitted by broadcast transmission (step S140).

When the process of step S140 ends, the base station 10 ends the first transmission process.

FIG. 4 is a flowchart of data reception processing of the terminal.

The reception process is started when data is transmitted from the base station 10 by broadcast transmission.

When data is transmitted by broadcast transmission from the base station 10, the terminal 20 operating in the non-power saving mode receives the data (step S200).

Upon receiving the data, the terminal 20 operating in the non-power saving mode acquires the sequence number assigned to the received data (step S210).

After acquiring the sequence number, the terminal 20 operating in the non-power-saving mode checks whether or not it has previously received data with the same sequence number that was transmitted by broadcast transmission (step S220).

In the process of step S220, if data with the same sequence number transmitted by broadcast transmission has been received in the past (step S220: Yes), the terminal 20 operating in the non-power saving mode The data obtained is discarded (step S230).

When the process of step S230 is completed, and when data with the same sequence number transmitted by broadcast transmission has not been received in the process of step S220 in the past (step S220: No), The terminal 20 operating in power saving mode terminates its reception processing.

A specific example of communication between the base station 10 and the terminal 20 in the communication system 1 will be described below.

FIG. 5 is a timing chart showing a specific example of communication between the base station 10 and the terminal 20. As shown in FIG.

In this specific example, the base station 10 acquires data for transmission for the first time at time t0, and then transmits beacons at times t1 and t3. Then, the base station 10 acquires the second transmission data at time t4. On the other hand, the power-saving terminal 22 is in power-saving mode at time t0 and time t4, and spontaneously switches its operation mode from power-saving mode to non-power-saving mode at time t5 after time t4.

At time t0, when the acquisition unit 11 acquires the first transmission data in the base station 10, the transmission unit 12 promptly broadcasts the transmission data acquired by the acquisition unit 11. FIG. Then, the non-power-saving terminal 21 receives the transmission data. In this way, when the acquisition unit 11 acquires transmission data, the non-power-saving terminal 21 can promptly receive the transmission data. On the other hand, since the power saving terminal 22 is in the power saving state at time t0, it does not receive the transmission data.

At time t1, in the base station 10, the beacon transmission unit 13 transmits a beacon including an instruction to switch the terminal 20 in the power saving mode to the non-power saving mode. Retransmit the transmission data. At this time, the transmission unit 12 assigns the same sequence number to the transmission data to be transmitted this time as the sequence number assigned to the transmission data at the time of transmission at time t0, and retransmits the data. Then, the non-power-saving terminal 21 receives the transmission data. Since the sequence number assigned to the received transmission data is the same as the sequence number assigned to the data received in the past, the non-power-saving terminal 21 discards the received transmission data. In this way, even if the non-power-saving terminal 21 receives transmission data redundantly, it can discard the redundantly received transmission data. On the other hand, the power saving terminal 22 receives the beacon transmitted at time t1 and switches its operation mode from the power saving mode to the non-power saving mode. Then, the power saving terminal 22 receives the transmitted transmission data at time t2. Thus, the power-saving terminal 22 can receive transmission data although the reception timing is later than that of the non-power-saving terminal 21 . In the base station 10, when the transmission unit 12 retransmits the transmission data, the acquisition unit 11 discards the temporarily stored transmission data.

At time t3, the beacon transmission unit 13 in the base station 10 transmits a beacon. At this time, since there is no transmission data temporarily stored in the acquisition unit 11, the transmission unit 12 does not perform broadcast transmission.

At time t4, when the acquisition unit 11 acquires the second transmission data in the base station 10, the transmission unit 12 promptly broadcasts the transmission data acquired by the acquisition unit 11. FIG. Then, the non-power-saving terminal 21 receives the transmission data. In this way, when the acquisition unit 11 acquires transmission data, the non-power-saving terminal 21 can promptly receive the transmission data. On the other hand, since the power saving terminal 22 is in the power saving state, it does not receive the transmission data.

At time t5, the power-saving terminal 22 spontaneously switches its operation mode from the power-saving mode to the non-power-saving mode, and transmits a notification signal. Then, the receiving unit 14 receives the notification signal, and the transmitting unit 12 retransmits the transmission data by broadcast transmission at time t6. At this time, the transmission unit 12 assigns the same sequence number to the transmission data to be transmitted this time as the sequence number assigned to the transmission data at the time of transmission at time t4, and retransmits the data. Then, the non-power-saving terminal 21 receives the transmission data. Since the sequence number assigned to the received transmission data is the same as the sequence number assigned to the data received in the past, the non-power-saving terminal 21 discards the received transmission data. In this way, even if the non-power-saving terminal 21 receives transmission data redundantly, it can discard the redundantly received transmission data. On the other hand, the power saving terminal 22 receives the transmitted transmission data at time t6. Thus, the power-saving terminal 22 can receive transmission data although the reception timing is later than that of the non-power-saving terminal 21 . In the base station 10, when the transmission unit 12 retransmits the transmission data, the acquisition unit 11 discards the temporarily stored transmission data.

As described above, according to the base station 10, even when the non-power-saving terminals 21 and the power-saving terminals 22 are connected to the base station 10, the terminals 20 other than the power-saving terminals 22 (that is, The non-power-saving terminal 21) receives the transmission data transmitted by broadcast transmission without delay compared to the case where the power-saving terminal 22 is not connected to the base station 10, and also transmits the data to the power-saving terminal 22. Credit data can be received.

On the other hand, when the power-saving terminal 22 is connected, the power-saving terminal 22 performs broadcast transmission in accordance with the timing at which data can be received. hereinafter also referred to as "first comparison base station"). When the first comparison base station acquires transmission data at time t0 in FIG. 5 when the non-power-saving terminal 21 is connected, the first comparison base station broadcasts the transmission data only at time t2 in FIG. send. Therefore, according to the first comparison base station, the non-power-saving terminal 21 connected to the first comparison base station can In comparison, the reception timing of transmission data transmitted by broadcast transmission is delayed. If the reception timing of the transmission data transmitted by broadcast transmission is delayed, for example, if the transmission data is audio data in an audio broadcast program broadcast on the non-power-saving terminal 21, the audio broadcast program The audio in the will be delayed. Further, if the reception timing of the transmission data transmitted by broadcast transmission is delayed, for example, the transmission data may be used for synchronizing the time of the first comparison base station and the time of the non-power-saving terminal 21. If it is a synchronization signal, the time of the first comparison base station and the time of the non-power-saving terminal 21 cannot be correctly synchronized.

Next, even if the power-saving terminal 22 is connected, the power-saving terminal 22 broadcasts transmission data regardless of the timing at which data reception becomes possible. However, the base station according to the second comparative example (hereinafter also referred to as the "second comparative base station") does not retransmit the transmission data in accordance with the timing when the data can be received. ). When the second comparison base station acquires the transmission data at time t0 in FIG. 5, it can immediately broadcast the transmission data. However, the second comparison base station does not retransmit the transmission data even at time t2 in FIG. Not performed. Therefore, according to the second base station for comparison, the power-saving terminal 22 connected to the second base station for comparison is transmitted at a timing other than the timing at which the power-saving terminal 22 can receive data. data for transmission cannot be received.

(Embodiment 2)
A communication system according to Embodiment 2, which is configured by partially changing the communication system 1 according to Embodiment 1, will be described below. In the following, regarding the communication system according to Embodiment 2, the same components as in the communication system 1 have already been described, and the same reference numerals are assigned to the same components, and detailed description thereof will be omitted. Differences from the communication system 1 will be mainly explained.

The communication system according to the second embodiment is configured by changing the base station 10 from the communication system 1 to the base station according to the second embodiment.

FIG. 6 is a configuration diagram of the base station 10a according to the second embodiment.

As shown in FIG. 6, the base station 10a is configured by changing the transmitter 12 from the base station 10 according to Embodiment 1 to a transmitter 12a.

The transmission unit 12 a broadcasts the transmission data acquired by the acquisition unit 11 . Further, the transmission unit 12a retransmits the transmission data acquired by the acquisition unit 11 to the power-saving terminal 22 at the timing when the power-saving terminal 22 can receive data. At this time, the transmission unit 12 retransmits the transmission data by unicast transmission instead of by broadcast transmission. The transmission data retransmitted by the transmission unit 12a is the transmission data acquired by the acquisition unit 11 and temporarily stored.

The transmission unit 12a retransmits the transmission data at the timing when the beacon transmission unit 13 transmits the beacon, so that the power saving terminal 22 retransmits the transmission data at the timing when the data can be received. I do. In addition, the transmission unit 12a retransmits the transmission data at the timing indicated by the notification signal from the power saving terminal 22 when the data can be received, so that the power saving terminal 22 can receive the data. The data for transmission can be received at the appropriate timing.

When there are a plurality of power-saving terminals 22 connected to the base station 10a, the transmission unit 12a retransmits transmission data by unicast transmission by a polling method according to a predetermined sequence. Further, when the number of power saving terminals 22 connected to the base station 10a is one, the transmission unit 12a retransmits transmission data by unicast transmission without using the polling method.

The operation performed by the communication system according to Embodiment 2 having the above configuration will be described below.

In the communication system according to Embodiment 2, the base station 10a performs second transmission processing for transmitting transmission data.

FIG. 7 is a flowchart of the second transmission process.

The second transmission process is started when transmission data is transmitted from the server 30 to the base station 10a via the network 40. FIG.

In the second transmission process, the process of step S300 to the process of step S320 are different from the process of step S100 to the process of step S120 in the process of the second transmission process (see FIG. 3, etc.) according to the first embodiment. This is the same processing as the processing in which the transmission unit 12 is read as the transmission unit 12a. Therefore, here, since the processing of step S300 to the processing of step S320 has already been explained, the detailed explanation thereof will be omitted, and the processing of step S330 to step S350 will be mainly explained. Also, the retransmission timing of the transmission data in Embodiment 2 will be described based on the period of beacon transmission from the base station 10a.

When the power-saving terminal 22 becomes capable of receiving data (step S320: Yes), the transmitting unit 12 checks whether or not there are a plurality of power-saving terminals 22 connected to the base station 10a (step S330).

In the processing of step S330, if there are a plurality of power-saving terminals 22 connected to the base station 10a (step S330: Yes), the transmission unit 12 performs transmission by a unicast method based on a polling method according to a predetermined sequence. The credit data is resent (step S340).

In the process of step S330, if there are not a plurality of power saving terminals 22 connected to the base station 10a (step S330: No), the transmission unit 12 retransmits the data for transmission by unicast method not based on the polling method. (step S350).

When the process of step S340 ends and when the process of step S350 ends, the base station 10a ends the second transmission process.

A specific example of communication between the base station 10a and the terminal 20 in the communication system according to the second embodiment will be described below.

FIG. 8 is a timing chart showing a specific example of communication between the base station 10a and the terminal 20. In FIG.

In this specific example, the base station 10a acquires data for transmission for the first time at time t0, and then transmits beacons at times t1 and t3. Then, the base station 10a acquires the second transmission data at time t4. On the other hand, the power-saving terminal 22 is in power-saving mode at time t0 and time t4, and spontaneously switches its operation mode from power-saving mode to non-power-saving mode at time t5 after time t4.

At time t0, when the acquisition unit 11 acquires the first transmission data in the base station 10a, the transmission unit 12a promptly broadcasts the transmission data acquired by the acquisition unit 11. FIG. Then, the non-power-saving terminal 21 receives the transmission data. In this way, when the acquisition unit 11 acquires transmission data, the non-power-saving terminal 21 can promptly receive the transmission data. On the other hand, since the power saving terminal 22 is in the power saving state, it does not receive the transmission data.

At time t1, when the beacon transmission unit 13 transmits a beacon in the base station 10a, the transmission unit 12a retransmits transmission data by unicast transmission to the power saving terminal 22 at time t2. Since this retransmission is a unicast transmission intended for the power saving terminal 22, the non-power saving terminal 21 does not receive the retransmitted transmission data. On the other hand, the power saving terminal 22 receives the beacon transmitted at time t1 and switches its operation mode from the power saving mode to the non-power saving mode. Then, the power saving terminal 22 receives the transmitted transmission data at time t2. Thus, the power-saving terminal 22 can receive transmission data although the reception timing is later than that of the non-power-saving terminal 21 . In the base station 10a, when the transmission unit 12a retransmits the transmission data, the acquisition unit 11 discards the temporarily stored transmission data.

At time t3, the beacon transmitting unit 13 transmits a beacon in the base station 10a. At this time, since there is no transmission data temporarily stored in the acquisition unit 11, the transmission unit 12a does not perform broadcast transmission.

At time t4, when the acquisition unit 11 acquires the second transmission data in the base station 10a, the transmission unit 12a promptly broadcasts the transmission data acquired by the acquisition unit 11. FIG. Then, the non-power-saving terminal 21 receives the transmission data. In this way, when the acquisition unit 11 acquires transmission data, the non-power-saving terminal 21 can promptly receive the transmission data. On the other hand, since the power saving terminal 22 is in the power saving state, it does not receive the transmission data.

At time t5, the power-saving terminal 22 spontaneously switches its operation mode from the power-saving mode to the non-power-saving mode, and transmits a notification signal. Then, the receiving unit 14 receives the notification signal, and the transmitting unit 12a retransmits the data for transmission by unicast transmission to the power saving terminal 22 at time t6. Since this retransmission is a unicast transmission intended for the power saving terminal 22, the non-power saving terminal 21 does not receive the retransmitted transmission data. On the other hand, the power saving terminal 22 receives the transmitted transmission data at time t6. Thus, the power-saving terminal 22 can receive transmission data although the reception timing is later than that of the non-power-saving terminal 21 . In the base station 10a, when the transmission unit 12a retransmits the transmission data, the acquisition unit 11 discards the temporarily stored transmission data.

As described above, according to the base station 10a, even when the power-saving terminal 22 is connected to the base station 10a, the terminal 20 other than the power-saving terminal 22 (that is, the non-power-saving terminal 21) broadcasts The transmission data to be transmitted by transmission can be received without delay as compared with the case where the power saving terminal 22 is not connected to the base station 10, and the power saving terminal 22 can also receive the transmission data.

(Other embodiments)
Although the base station according to the present invention has been described above based on Embodiment 1 and Embodiment 2, the present invention is not limited to these embodiments. As long as it does not deviate from the spirit of the present invention, the present embodiment includes various modifications conceived by those skilled in the art, and a form constructed by combining the components of different embodiments are also included in the scope of the present invention. .

(1) In Embodiments 1 and 2, when the power-saving terminal 22 receives a beacon transmitted from the base station 10 in the power-saving mode, it changes its operation mode from the power-saving mode. It has been described as switching to a non-power saving mode. However, if the power-saving terminal 22 can switch its operation mode from the power-saving mode to the non-power-saving mode in synchronization with the transmission of the beacon by the base station 10, the power-saving terminal 22 can transmit the beacon by the base station 10 by another method. Synchronously with the transmission, it may switch its mode of operation from power saving mode to non-power saving mode. For example, the beacon transmitted from the base station 10 includes information indicating the timing at which the base station 10 transmits the beacon (for example, information indicating the transmission cycle of the beacon that is periodically transmitted, etc.). Once the terminal 22 receives the beacon transmitted from the base station 10, the terminal 22 thereafter selects its own operation mode in synchronization with the transmission of the beacon by the base station 10 based on the information contained in the received beacon. , the power saving mode may be switched to the non-power saving mode.

(2) Each step in the first transmission process, the reception process, and the second transmission process in Embodiments 1 and 2 may be executed by a computer (computer system). Further, the present invention can be implemented as a program for causing a computer to execute each step in the first transmission process, the reception process, and the second transmission process. Furthermore, the present invention can be implemented as a non-temporary computer-readable recording medium such as a CD-ROM recording the program.

For example, when the present invention is implemented by a program (software), each step is executed by executing the program using hardware resources such as the CPU, memory, and input/output circuits of the computer. . That is, each step is executed by the CPU acquiring data from a memory, an input/output circuit, or the like, performing an operation, or outputting the operation result to the memory, an input/output circuit, or the like.

(3) A plurality of components included in base station 10 and base station 10a in Embodiments 1 and 2 may each be implemented as a dedicated or general-purpose circuit. These components may be implemented as one circuit or as multiple circuits.

Also, a plurality of components included in the base station 10 and the base station 10a may be implemented as an LSI (Large Scale Integration), which is an integrated circuit (IC). These components may be made into one chip individually, or may be made into one chip so as to include some or all of them. LSIs are sometimes called system LSIs, super LSIs, or ultra LSIs depending on the degree of integration.

Also, the integrated circuit is not limited to an LSI, and may be realized by a dedicated circuit or a general-purpose processor. As described above, a programmable FPGA or a reconfigurable processor in which connections and settings of circuit cells inside the LSI can be reconfigured may be used.

Furthermore, if an integrated circuit technology that replaces LSI emerges due to advances in semiconductor technology or another technology derived from it, it will of course be possible to integrate each component included in the repeater using that technology. good.

(4) In addition, forms obtained by applying various modifications that a person skilled in the art can think of to Embodiments 1 and 2, and components and functions in each embodiment without departing from the spirit of the present invention. The present invention also includes forms realized by combining them arbitrarily.

INDUSTRIAL APPLICABILITY The present invention can be widely used in base stations and the like for communication.

Reference Signs List 1 information providing system 10, 10a base station 11 acquisition unit 12, 12a transmission unit 13 beacon transmission unit 14 reception unit 20 terminal 21, 21a, 21b, 21c non-power-saving terminal 22, 22a power-saving terminal

Claims (9)

A base station that communicates with a plurality of terminals including one or more power saving terminals,
an acquisition unit that acquires transmission data;
a transmission unit that performs broadcast transmission of the transmission data acquired by the acquisition unit;
The transmission unit broadcasts the transmission data acquired by the acquisition unit to the plurality of terminals, and at a timing when the one or more power saving terminals can receive data, the acquisition unit A base station that retransmits the acquired transmission data. Furthermore, it has a beacon transmission unit that periodically transmits a beacon,
The one or more power saving terminals can receive data at the timing when the beacon is transmitted from the beacon transmission unit,
The base station according to Claim 1, wherein the transmission section performs the retransmission at the timing when the beacon transmission section transmits the beacon. further comprising a receiving unit that receives a notification signal indicating a timing at which data reception becomes possible, which is transmitted from each of the one or more power saving terminals;
The base station according to claim 1, wherein the transmitting section performs the retransmission at a timing indicated by the notification signal received by the receiving section, at which data can be received. The base station according to claim 2 or 3, wherein the transmission section performs the retransmission by broadcast transmission. 5. The transmitting unit according to claim 4, wherein the transmission sequence number assigned to the transmission data in the retransmission is the same as the transmission sequence number assigned to the transmission data in broadcast transmission performed prior to the retransmission. base station. The base station according to claim 2 or 3, wherein the transmission section performs the retransmission by unicast transmission. The one or more power saving terminals are a plurality of power saving terminals,
7. The base station according to claim 6, wherein the transmission section performs the retransmission by the unicast transmission to the plurality of power saving terminals by a polling method according to a predetermined sequence. the base station and the plurality of terminals perform communication conforming to the IEEE 802.11 standard;
The one or more power saving terminals are terminals that enter a power saving mode according to the IEEE802.11 standard,
The base station according to Claim 2, wherein the beacon transmission unit periodically transmits the beacon at DTIM intervals in the IEEE802.11 standard. A communication method performed by a base station communicating with a plurality of terminals including one or more power saving terminals,
an acquisition step for acquiring data for transmission;
a transmission step of broadcasting the transmission data acquired in the acquisition step;
and a retransmitting step of retransmitting the transmission data acquired in the acquiring step at a timing at which the one or more power saving terminals can receive data.

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