JP2003258813A - Receiving station housed in communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication system capable of avoiding the collision of affirmative response. <P>SOLUTION: Three receiving stations 12<SB>1</SB>to 12<SB>3</SB>receive a packet broadcasted or multicasted by a transmitting station 11, and one receiving station 12<SB>1</SB>among them returns to the transmitting station 11 a response including a number specifying the packet that has been successfully received. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system, and more particularly to a communication system in which a data transmitting station simultaneously transmits data to a plurality of receiving stations such as multicast or broadcast.

[0002]

2. Description of the Related Art Generally, when a transmitting station multicasts or broadcasts data to a receiving station via a wired transmission line, the receiving station does not return an acknowledgment of data reception to the transmitting station. This is because a substantially constant transmission quality can be expected in data transmission via a wired transmission path. On the other hand, the transmission quality in wireless communication is worse than that in wired communication, and depends largely on the state of radio waves. Therefore, from the viewpoint of improving the transmission quality, it is preferable that each receiving station be able to resend an affirmative response even during multicast or broadcast in wireless communication.

[0003]

However, if an affirmative response is returned in this way, a plurality of receiving stations will send out an affirmative response to the wireless transmission path almost at the same time during multicast or broadcast, so that wireless transmission will be performed. There was a problem that a collision of positive responses occurred on the road. In addition, there is a problem that the transmission station delays the transmission of the next data due to the transmission of a plurality of positive responses.

Therefore, it is an object of the present invention to provide a communication system which can avoid collision of acknowledgments.

[0005]

The above objects can be achieved by the following inventions. The present invention is a receiving station that is housed in a communication system and receives data from a data transmitting station, and a determining unit that determines whether or not the receiving station is a response transmitting station. When it is determined that there is such a data, a transmission unit that transmits to the data transmission station a response that allows the data transmission station to specify the data that has failed to be received. As a result, it is possible to limit the receiving stations that send the response, and it becomes difficult for the responses to collide on the wireless transmission path.

[0006] Preferably, when i (i is a natural number of 2 or more) receiving stations are accommodated in the communication system, (i-1) receiving stations serve as response transmitting stations and transmit responses. Send to. As a result, all the received data do not return the response to the transmitting station, so that the response is less likely to collide on the wireless transmission path.

More preferably, only one receiving station transmits a response to the transmitting station as a response transmitting station. This allows
In principle, the responses will not collide on the wireless transmission path.

[0008] Preferably, the data transmitting station further retransmits the data based on the reception response. This improves the transmission quality.

Further, preferably, the receiving station is set as the response transmitting station based on the distance from the data transmitting station. As a result, the data transmitting station can determine with high accuracy whether or not the i receiving stations were able to receive the data even with the response from the (i-1) station.

Further, the receiving station, which is located farthest from the data transmitting station, is set as the response transmitting station. This makes it possible to know with high accuracy the station that has failed to receive data.

Further, as the receiving station, the station closest to the data transmitting station is set as the response transmitting station. As a result, the transmitting station can know with high accuracy the station that has successfully received the data. As a result, the data transmission station
Even with the response from the (i-1) unit, it is possible to determine with high accuracy whether or not the i receiving stations have received the data.

Further, preferably, the receiving station is set as a response transmitting station based on the success rate of data reception. This allows the transmitting station to determine with high accuracy whether or not the i receiving stations have been able to receive data, even if the response is from the (i-1) station.

Further, it is preferable that the receiving station having the lowest success rate is set as the response transmitting station. This makes it possible to know with high accuracy the receiving station that has failed to receive data.

The receiving station having the highest success rate is set as the response transmitting station. This makes it possible to know with high accuracy the station that has successfully received the data.

Another aspect of the present invention is, firstly, a communication system in which data transmission stations that simultaneously transmit data to i (i is a natural number of 2 or more) reception stations and data that has failed to be received. It is provided with (i-1) or less receiving stations that transmit a response that can be specified on the data transmitting station side to the data transmitting station. Furthermore, another aspect of the present invention is a data transmission method, which comprises a data transmission step in which the data transmission station simultaneously transmits data to i (i is a natural number of 2 or more) receiving stations.
At least two receiving stations include a response transmitting step of transmitting, to the data transmitting station, a response that allows the data transmitting station to specify the data that has failed to be received.

According to the above-described two other modes, since all the received data do not return the response to the transmitting station, the response is less likely to collide on the wireless transmission path.

A third other aspect is a data transmission station that is accommodated in a communication system and transmits data to a plurality of reception stations at the same time, and the reception power of the data is received by each reception station. And a setting unit that sets one of the receiving stations as a response transmitting station based on the received power transmitted from each receiving station. . Here, the receiving station is characterized in that, when the receiving station is set as the response transmitting station, the receiving station transmits to the data transmitting station a response capable of specifying the data that has failed to be received. As a result, the data transmitting station can automatically set the response transmitting station based on the received power from each receiving station.

A fourth other mode is a data transmitting station which is accommodated in the communication system and which transmits data to a plurality of receiving stations at the same time. A control signal transmitting unit for transmitting a control signal for requesting the transmission of a rate, and a setting unit for setting one of the receiving stations as a response transmitting station based on the reception success rate transmitted from each receiving station. Equipped with. Here, the receiving station is characterized in that, when the receiving station is set as the response transmitting station, the receiving station transmits to the data transmitting station a response capable of specifying the data that has failed to be received. As a result, the data transmission station can automatically set the response transmission station based on the reception success rate from each reception station.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, with reference to the drawings, detailing the wireless communication system 1 _a according to an embodiment of the present invention.

First, the wireless communication system 1_a Fig.
This will be described with reference to FIG. The wireless communication system 1 of FIG._a so
Is one transmitting station 11 and i receiving stations 12₁~ 12_i
Perform data transmission through the wireless transmission path. here,
i is a natural number of 2 or more, but is 3 for convenience.
The following explanation will be continued. In addition, the receiving station 12₁~ 12 _i
Among them, at most (i-1) units are ACK transmissions which will be described later.
It also has a function as a receiving station. In this embodiment, for convenience,
Bureau 12₁Only has the function of ACK transmitter
I assume.

Next, see FIG. 2 for an outline of the above data transmission.
I will explain. Now, the transmitting station 11 uses the j packets P
_kUsing this wireless communication system 1_aHoused in
All receiving stations 12₁~ 12_iSend some data to
Suppose we have to broadcast.
More specifically, the transmitting station 11 sets m for each cycle.
Packets P_kAnd broadcast such a
By repeating the loadcast n cycles, all the parts are
Ket P_kTo broadcast. Where j is the sending
This is a natural number that depends on the size of the received data, and
Then, it is assumed that it is 8 for convenience. Also, k is from 1 to j
Is a natural number of. In addition, m is for data transmission.
This is a natural number that depends on the allocated bandwidth, and
Then, assume 5. Furthermore, n is each packet P_kRe
Receiving station 12 without transmission ₁~ 12_iBut all packets
To P_kIs received, it is (j / m) quotient, or
It becomes the value which added 1 to. For example, as above, j is 8
And when m is 5, all packets P_kBroadcast
Requires 2 cycles.

Further, each packet P_kAs shown in Figure 3
The number N_kAnd flag F_kAnd the payload L_kIncluding and
Mu. Number N_kIs each packet P_kThe transmission order of is shown. Well
And flag F_kIs set to either the first value or the second value.
Be done. The first value is the packet P _kAt the end of each cycle
Indicates that it was not sent. Conversely, the second value is
Packet P_kIs the one sent at the end of each cycle
Indicates that For example, like the above assumption, each cycle
5 packets P in_kIs sent first,
And the fourth packet P_kTo the flag F_kAs the first
Value is set and the fifth packet P_kOnly to the second
The value is set. Payload L_kSend data in advance
It is divided into a specified size.

Under the above-mentioned assumption, the transmitting station 11 first transmits all the receiving stations 2 through the wireless transmission path as shown in FIG.
It transmits the packet P ₁ in 21 _{to 3,} that is broadcast. Further, the control station 11 broadcasts the next packet P ₂ when a predetermined time has elapsed from the transmission of the packet P ₁ . Similarly, the control station 11 broadcasts the packets P _{3 to} P ₅ after a predetermined time has passed since the previous packet transmission.

Each of the receiving stations 12 _{1 to} 12 ₃ receives the packet P ₁
Of to P _5, what correctly received and stored in the internal receive buffer (not shown). Here, for convenience of explanation, the packet P ₂ is not received by the receiving station 12 ₁ , and the packet P ₃ is not received by all the receiving stations 12 _{1 to} 12 ₃ .
Suppose packet P ₅ was not received by receiving station 12 ₃ .

As the ACK transmitting station, the receiving station 12 ₁ stores the number N _k contained in the packet P _k each time the packet P _k is stored in the receiving buffer, in addition to the above-described receiving process. Furthermore, the receiving station 12 ₁ receives each received packet P
_When the value of the flag F _k of _k is checked and it is confirmed that the packet P _k transmitted last in this cycle is received based on the value, a response ACK _n is generated. Here, the response ACK _n includes at least the number N _k currently stored in order to identify the packet P _k received in this cycle, as shown in FIG. For example, if packets P ₁ , P ₄ and P ₅ are received by the receiving station 12 _{1 in the first} cycle as in the above assumption,
The numbers N ₁ , N ₄ and N ₅ are set in the response ACK ₁ . The receiving station 12 ₁ receives the response ACK _n as described above.
It transmits to the transmitting station 11 through a wireless transmission path. After the transmission is completed, the receiving station 12 ₁ erases the stored number N _k .

By confirming the number N _k in the reception response ACK _n , the transmitting station 11 receives the receiving station 12 _{1 in} this cycle.
The packet P _k that could not be received (hereinafter, referred to as a retransmission packet P _k ) can be known. It should be noted here that the transmitting station 11 considers that the retransmission packet P _k cannot be received by all the receiving stations 12 _{1 to} 12 ₃ , and FIG.
As shown in, the retransmission packet P _k is broadcast at the beginning of the next cycle, and after the retransmission is completed, the untransmitted packet P _k is broadcast in the transmission order. According to the above assumption, immediately after the start of the second cycle,
The retransmission packets P ₂ and P ₃ are broadcast to the transmitting station 11. Here, note that the receiving station 1
2 ₃ does not correctly receive the packet P ₅ in the first cycle, but since the response ACK ₁ does not include the number N ₅ , the transmitting station 11 does not retransmit the packet P ₅ . After the end of such retransmission, the packets P _{6 to} P ₈ are broadcast in the same manner as described above.

Each receiving station 12₁~ 12₃Is received correctly
Packet P that came_kIs stored in the internal receive buffer.
Here, for convenience of explanation, the packet P₂Is the receiving station 12₃By
Packet P₆Is all receiving stations 12₁~ 1
Two₃Suppose it was not received by. Such a provisional
Under normal conditions, the receiving station 12₁From the number N₂, N₃, N ₇
And N₈Response ACK containing₂Is transmitted to the transmitting station 11.
Be done. Transmitting station 11 responds with ACK₂After the 3rd cycle
At the beginning of the retransmission packet P₆Will be broadcast
It

As described above, the wireless communication system 1
_{In a} , all the receiving stations 12 ₁ to
Since 12 ₃ is prevented return a response ACK _n to the transmitting station 11, the response ACK _n hardly collide with the radio transmission path. Here, the response ACK _n is most preferably transmitted by the single receiving station 121 as described above. This is because, in principle, collision of response ACK _n does not occur on the wireless transmission path. With the wireless communication system 1 _a as described above, it is possible to suppress the delay in data transmission due to the collision of the response ACK _n .

In the above embodiments, data transmission during broadcasting has been described. However, the present invention is not limited to this, and the above-described data transmission can be applied to the case of transmitting data to a plurality of receiving stations 12 _{1 to} 12 _i , that is, the case of multicasting.

Next, the transmitting station 11 and the receiving stations 12 ₁ to 12 ₁
The detailed configuration of the 2 _3, will be described with reference to FIGS. First, in FIG. 5, the control station 11 performs transmission of the above-mentioned data by the transmission buffer 111, the controller 112, the transceiver 113, and the retransmission buffer 11.
It is equipped with 4. The transmission buffer 111 stores the unprocessed packet P _k ′ assembled in the upper layer. The unprocessed packet P _k 'has the number N _k compared to the packet P _{k of} FIG.
The difference is that is not added. Controller 112
Performs the processing required for the above data transmission. As one of those processes, the controller 112 adds the number N _k to the unprocessed packet P _k ′ to generate the packet P _k . The transmitter / receiver 113 mainly sends the packet P _k generated by the controller 112 to the wireless transmission path and receives the response ACK _n transmitted via the wireless transmission path.
The retransmission buffer 114 stores the retransmission packet P _k .

Further, in FIG. 6, the receiving station 12₁~ 12
₃For transmitting and receiving the above-mentioned data,
The communication buffer 122 and the controller 123 are provided.
It The transceiver 121 is mainly connected to the wireless transmission line 13.
Packet P sent as _kReceive the controller
Response ACK generated in 123_nTo the wireless transmission path
It The reception buffer 122 is a reception packet of the transceiver 121.
Tut P_kTo store. The controller 123 uses the above-mentioned data.
Performs necessary processing for data transmission.

Next, the control station 11 and the receiving stations 12 ₁ to 12 ₁
Detailed processing of 2 _3, will be described with reference to FIGS. Here, FIG. 7 is a flowchart showing the processing of the control station 11. For convenience of explanation below,
It is assumed that the unprocessed packet P _k ′ is stored in the transmission buffer 111 before the start of processing in FIG. 7. In FIG. 7, the controller 112 of the control station 11 uses the packet P _k.
The value k of a counter (not shown) indicating the transmission order of is set to 1 (step SA1). Next, the controller 112
Determines whether or not the retransmission packet P _k is stored in the retransmission buffer 114 (step SA2), and if stored, performs step SA9 described later.

On the contrary, when the retransmitted packet P _k is not stored, the controller 112 determines that one packet P _k is stored.
After sending _k , the counter value k is incremented by 1 (step SA3). Describing specifically the transmission of the packet P _k , first, one processing target packet P _k ′ is selected from the transmission buffer 111 according to the transmission order.
After that, the current counter value k is added to the processing target packet P _k ′.
Is added as a number N _k , and a flag F _k is further added. As a result, the packet P _k is generated. here,
In the processing target packet P _k ′ selected from the 1st to m−1th cycles in this cycle, the current counter value k
Is added as the number N _k , and further, the first value is added as the flag F _k . In addition, in the current cycle, the counter value k is added as the number N _k and the second value is added as the flag F _k to the m-th processing target packet P _k ′. The packet P _k generated as described above is sent to the wireless transmission path through the transmitter / receiver 113. After the above step SA3, the controller 1
12 determines whether m packets P _k have been transmitted (step SA4), and if not transmitted, step SA3
Do it again.

On the contrary, if the data has been transmitted, the controller 112
Based on the response ACK _n transmitted from the receiving station 12 ₁ , the m number of packets P _k transmitted in this cycle
Is received (step SA)
5). If received, m packets P _k generated this time
Are discarded because they are not required to be retransmitted (step SA6). Conversely, if there is more than one packet P _k that has not been received, the controller 112 sends them a retransmit packet P _k.
Is stored in the retransmission buffer 114 as, and the received portion is discarded (step SA7). Step S above
After A6 or SA7, the controller 112 determines whether the counter value k has reached the total number j of the packets P _k (step SA8). If the counter value k is greater than or equal to the total number j, the controller 112 performs step SA2 again. If not, the data transmission ends.

Further, in step SA2 described above,
Transmission packet P_kIs stored, controller 1
12 is one retransmission packet P_kAfter sending the
Data value k is incremented by 1 (step SA
9). Retransmitted packet P_kSpecifically, the transmission of
First, from the transmission buffer 111, one retransmission packet P
_k, According to the transmission order, and then the selected retransmission packet.
To P_kTo flag F_kReset. Here, this time
Of the retransmission packets selected from the 1st to m-1st
Ket P_kTo the flag F_kThe first value is added as
It In addition, the retransmission packet P selected mth_kHas
Flag F_kThe second value is added as. The above resend packet
Ket P_kIs transmitted via the transmitter / receiver 113 to the wireless transmission line 13
Sent to. After the above step SA9,
Of the retransmission packet P _kWhether or not
It is judged (step SA10).
Repeat step SA9. On the contrary, if it has been sent,
Perform SA3. The controller 112 performs the above processing
By repeating the data transmission described with reference to FIG.
To do.

FIG. 8 is a flowchart showing the processing of the receiving station 12 _i . In FIG. 8, the transmitter / receiver 121 of the receiving station 12 waits for reception of the packet P _k transmitted through the wireless transmission path in each cycle (step SB1). When the transceiver 121 receives the packet P _{k in} step SB1, the transceiver 121 receives the packet P _k.
2 (step SB2). After storing the packet P _k , the controller 123 confirms the flag F _k of the received packet P _k of this time and determines whether or not the one sent last in this cycle is received (step SB).
3). If the flag F _k has the first value in step SB3, step SB1 is performed. On the other hand,
If the flag F _k is the second value, the controller 123
Since it has received the last packet P _k , it judges whether or not its own station is an ACK transmitting station (step S
B4). If it is not the ACK transmitting station in step SB4, step SB1 is performed. On the contrary, if it is an ACK transmitting station, the controller 123 extracts the number N _k from all the packets P _k stored in the receiving buffer 122, generates the response ACK _n containing them, and transmits it through the transmitter / receiver 121. The data is sent to the wireless transmission line 13 (step SB5). The controller 123 repeats the above processing to perform the data transmission described with reference to FIG.

Next, at the time of automatically setting the ACK transmitting station described above,
Control station 11 and receiving station 12 in ₁~ 12₃Detailed
The processing will be described with reference to FIG. Here, FIG.
Is a flow chart showing the processing of the control station 11 at the time of automatic setting.
It is In FIG. 9, the controller 1 of the control station 11
12 sets the value i of the counter (not shown) to 1.
(Step SC1). Here, the counter value i is the receiving station
12_iSpecify. Next, the controller 112 operates as shown in FIG.
As shown in 0, the MAC address corresponding to the counter value i
Space A_iControl signal CS including_iTo generate. Where MA
C address A_iIs the receiving station 12_iIs an identifier that identifies
It Control signal CS above_iThrough the transceiver 113
It is sent to the wireless transmission path (step SC2).

Receiving station 12_iThe transceiver 121 of the
Control signal CS through the transmission path_iIs received (step S
C3), the received power L_iIs measured (step SC
4). Measured received power L_iIs the controller 123
Sent to. The controller 123 is shown in FIG.
Sea urchin 12_iMAC address A_iAnd the received power L
_iNotification signal NS including and_iTo generate. Notification signal above
NS_iIs transmitted to the wireless transmission line through the transceiver 121.
(Step SC5).

The transmitter / receiver 113 of the transmitter station 11 receives the notification signal NS _i through the wireless transmission path (step S
C6), and sends it to the controller 112. The controller 112 stores the combination of the MAC address A _i and the received power L _i included in the notification signal NS _i in an internal storage area (not shown) (step SC7). After that, the controller 112 determines whether or not the control signal SC _i has been transmitted to all the receiving stations 12 _i (step SC
8) If not transmitted, the counter value i is incremented by 1 (step SC9), and then step S9.
Perform C2.

On the contrary, when it is determined in step SC8 that the data is transmitted to all the receiving stations 12 _i , the controller 112
In step SC10, the minimum received power L _i is searched from the storage area, and the MAC of the same set as the searched MAC is searched.
Take out the address A _i . That is, the controller 112
Identifies the receiving station 12 _i located farthest from its own station 11 (step SC10). After that, controller 1
12 receives the receiving station 12 _i identified in step SC10 as A
In order to specify the CK transmitting station, as shown in FIG. 12, M
A setting signal SS _i including the AC address A _i is generated and sent to the wireless transmission path through the transceiver 113 (step SC11).

The transmitter / receiver 121 of the receiving station 12 _i receives the setting signal SS _i through the wireless transmission path (step S
C12), and sends it to the controller 123. The controller 123 responds to the reception setting signal SS _i by sending data to the own station 12
Information indicating that _i is an ACK transmitting station is set (step SC13). When the above procedure is completed, the wireless communication system 1 _a, the data transmission as described with reference to FIG. 2 begins.

In the above description of automatic setting, the receiving station 12 _i located farthest from the transmitting station 11 is selected as the ACK transmitting station. Generally, the reception success rate of the packet P _k is lower as the reception station 12 _i is farther from the transmission station 11. Therefore, the packet P _k that can be received by such a receiving station 12 _i has a high probability that other receiving stations 12 _i can also receive it. Therefore, the transmitting station 11 specifies the farthest receiving station 12 _i as the ACK transmitting station,
The packet P _k that all the receiving stations 12 _i can receive can be known with high accuracy.

Note that, unlike the above description, the transmitting station 11
Is the receiving station 12 located closest to _iTo the ACK transmitting station
You may specify. Generally, the nearest receiving station 12_iBut
Packet P that could not be received_kIs the other receiving station 12_iAlso
It is more likely that you have not received it. This will send
The receiving station 11 is all receiving stations 12_iWas not received
To P_kCan be known with high accuracy.

[0044] In the above description, the automatic set at the start of the wireless communication system 1 _a has been performed, not limited to this, other timing (e.g., a specified time interval)
Then, automatic setting may be performed.

In the above description, the dedicated control signal C
The automatic setting was performed using S _i , but not limited to this,
Each receiving station 12 _i receives the received power of the packet P _k from the transmitting station 1 _i.
Alternatively, the transmitting station 11 may determine the ACK transmitting station based on such received power.

Further, in the above description, the ACK transmission station is determined based on the reception power L _i , but the present invention is not limited to this, and each reception station 12 _i can receive the packet P _k at a certain time interval. Is calculated and transmitted to the transmitting station 11, and the transmitting station 1
1 may determine the ACK transmission station based on such a reception success rate. In this case, the ACK transmission station, for the same reason as described above, it is preferable that the most successful reception rate is higher receiving station 12 _i or the most it is lower receiving station 12 _i is designated.

[0047]

As described in the foregoing, according to the radio communication system 1 _a, when the multicast or broadcast, the entire receiving station 12 _i which receives the packet P _k response A
Instead of returning CK _n to the transmitting station 11, some because (preferably one) the receiving station 12 _i of returns a response ACK _n, response ACK _n hardly collide with the radio transmission path.

[Brief description of drawings]

FIG. 1 is a wireless communication system 1 according to an embodiment of the present invention.
Block diagram indicate the general configuration of _a

FIG. 2 is a diagram showing an outline of data transmission in the wireless communication system 1 _a of FIG.

FIG. 3 is a diagram showing a format of each packet P _k transmitted in the wireless communication system 1 _a .

FIG. 4 is a response ACK transmitted by the wireless communication system 1 _a.
Diagram showing the format of _n

FIG. 5 is a block diagram showing a detailed configuration of a control station 11 of the wireless communication system 1 _a .

FIG. 6 is a block diagram showing a detailed configuration of a receiving station 12 _i of the wireless communication system 1 _a .

FIG. 7 is a flowchart showing the processing of the control station 11 of FIG.

FIG. 8 is a flowchart showing the processing of the receiving station 12 _{i in} FIG.

FIG. 9 is a control station 11 when the ACK transmitting station is automatically set.
And a flowchart showing the processing of the receiving stations 12 _{1 to} 12 _3.

FIG. 10 is a diagram showing a format of a control signal CS _i transmitted in step SC2 of FIG.

FIG. 11 is a diagram showing a format of a notification signal NS _i transmitted in step SC5 of FIG.

12 is a diagram showing the format of a setting signal SS _i sent in step SC10 of FIG.

[Explanation of symbols]

1 _a wireless communication system 11 control station 12 _i receiving station

Continued front page    F-term (reference) 5K014 AA01 DA02 FA03 FA11                 5K030 HA08 JL01 LA01 LA02 LD02                 5K033 CB04 CB13 CC01 DA17                 5K067 AA21 BB21 CC08 DD43 DD44                       DD51 EE02 EE10 FF02 FF16                       GG03 GG06 GG09 HH11 HH22                       HH28

Claims (14)

[Claims] 1. A receiving station that is housed in a communication system and receives data of a data transmitting station, the determining section determining whether or not the receiving station itself is a response transmitting station, and the response transmitting by the determining section. A receiving station, comprising: a transmitting unit for transmitting to the data transmitting station a response that allows the data transmitting station to specify data that has failed to be received when it is determined to be the station. 2. When i receiving stations (i is a natural number of 2 or more) are accommodated in the communication system, (i
-1) The receiving station according to claim 1, wherein the base transmits a response to the transmitting station as a response transmitting station. 3. The receiving station according to claim 2, wherein only one device transmits a response to the transmitting station as a response transmitting station. 4. The receiving station according to claim 2, wherein the data transmitting station further retransmits data based on a reception response. 5. The receiving station according to claim 2, wherein the receiving station is set as a response transmitting station based on a distance from the data transmitting station. 6. The receiving station according to claim 5, wherein the one farthest from the data transmitting station is set as a response transmitting station. 7. The receiving station according to claim 5, wherein the one closest to the data transmitting station is set as a response transmitting station. 8. The receiving station according to claim 2, which is set as a response transmitting station based on a success rate of data reception. 9. The receiving station according to claim 8, wherein the one with the lowest success rate is set as the response transmitting station. 10. The receiving station according to claim 8, wherein the one with the highest success rate is set as the response transmitting station. 11. A communication system, wherein a data transmitting station that simultaneously transmits data to i (i is a natural number of 2 or more) receiving stations and data that has failed to be received can be specified on the side of the data transmitting station. A communication system comprising (i-1) or less receiving stations that transmit a response to the data transmitting station. 12. A data transmission method, comprising: a data transmitting step in which a data transmitting station simultaneously transmits data to i (i is a natural number of 2 or more) receiving stations, and at least two receiving stations receive data. And a response transmitting step of transmitting, to the data transmitting station, a response that allows the data transmitting station side to specify failed data. 13. A data transmitting station, which is housed in a communication system and transmits data to a plurality of receiving stations at the same time, for requesting each of the receiving stations to transmit received power of data. Based on a control signal transmission unit that transmits a control signal, and the received power transmitted from each of the receiving stations,
A setting unit configured to set one of the receiving stations as a response transmitting station, wherein the receiving station, when the receiving station itself is set as a response transmitting station, transmits a response that can identify data that has failed to be received. A data transmission station characterized by transmitting to a station. 14. A data transmitting station, which is housed in a communication system and transmits data to a plurality of receiving stations simultaneously, for requesting each of the receiving stations to transmit a data reception success rate. A control signal transmitting section for transmitting a control signal of, and a setting section for setting one of the receiving stations as a response transmitting station based on the reception success rate transmitted from each of the receiving stations, wherein the receiving station A data transmitting station, which transmits a response capable of specifying data that has failed to be received, to the data transmitting station when itself is set as a response transmitting station.