KR101033149B1 - Communication system, communication apparatus, and data transmission method - Google Patents

Abstract

One or more communication devices that transmit the same data at the same time through multiple data transmissions using different methods of multiplexing are determined based on the link quality of the plurality of communication devices. Then, the determined communication apparatus transmits the same data according to the synchronized timing, thereby performing multiple data transmission. The link quality is determined by measuring the received signal strength, the bit error rate, or the frame error rate in each communication apparatus when multiplex data transmission is performed using two types of mutually orthogonal multiplexing.

Communication devices, different methods of multiplexing, link quality, multiple data transmission, received signal strength

Description

Technical Field [0001] The present invention relates to a communication system, a communication apparatus, and a data transmission method,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system, a communication apparatus, and a data transmission method constituted by a plurality of communication apparatuses.

2. Description of the Related Art In recent years, in home theaters and the like, stream data composed of a video signal and an audio signal is transmitted using a wireless communication technique. Therefore, in a communication system composed of a communication terminal and a control station which respectively control a plurality of loudspeakers, there is a demand for a technique capable of reproducing high-quality video and music without jamming without interruption or communication delay.

Up to now, in order to meet such a demand, proposals have been made to use a communication system in which all the communication apparatuses in a wireless network transmit the same data through a communication path redundant, thereby improving communication reliability.

Further, in order to realize a high communication rate by increasing the radio signal strength, there is a method in which a transmitting side transmits to a large number of receiving side using a wideband directional antenna and a receiving side uses a narrowband directional antenna to direct the directional beam toward a transmitting side It was proposed.

On the other hand, in order to always maintain good communication quality through redundant transmission, multiple transmission of polarization, code or frequency is used. For example, a technology has been devised to maintain good communication quality even when there is physical shielding in the communication path. This technique avoids communication shielding by redundantly transmitting the same data through a polarization multiplexing transmission in a plurality of transmission sources and using a polarization diversity reception at a reception terminal (for example, refer to Japanese Unexamined Patent Publication Japanese Patent Application Laid-Open No. 11-274994).

As another example, there is a method of assigning different polarized waves of the same frequency band in a redundant configuration including a radio line that performs communication with a redundant line when the active line is disconnected. In this case, by using a transmission line including an active line and a reserve line, to which different polarizations of the same frequency band are allocated, if one of the lines is disconnected, the other line occupies the place The frequency resource utilization efficiency is improved (see, for example, Japanese Patent Application Laid-Open No. 2001-86051).

However, in a communication system in which a control station and a plurality of communication devices perform broadcast communication, when the control station and each communication device have antenna directivity, sufficient link quality can not be acquired according to the arrangement between the devices, There is a case in which it is not established.

Therefore, until all the communication apparatuses in the communication system can reliably receive the same data with sufficient link quality, the number of communications with other communication apparatuses in the communication system is increased to increase redundancy and further improve communication reliability . However, this method is inefficient because there is a trade-off relationship between the reliability of the communication line and the number of communications. Further, if the number of communications is increased in order to improve the reliability, the communication time becomes long.

The present invention provides a communication system that improves communication efficiency and improves the reliability of communication.

According to an aspect of the present invention, there is provided a communication system comprising a plurality of communication devices, each of which simultaneously transmits data through multiple data transmissions using different methods of multiplexing, based on the link quality of each communication device, And a transmission means for performing the multiple data transmission according to the timing at which the communication devices determined by the first determination means are synchronized with each other.

According to another aspect of the present invention, there is provided a communication apparatus in a communication system composed of a plurality of communication apparatuses, which, based on the link quality of each communication apparatus, Determining means for determining communication apparatuses that simultaneously transmit data via transmission and notification means for notifying the communication apparatuses determined by the determining means of multiplexing the different methods to be used for the multiple data transmission .

According to still another aspect of the present invention, there is provided a data transmission method for use in a communication system comprising a plurality of communication devices, the data transmission method comprising the steps of: And a step of performing the multiple data transmission according to a timing at which the communication devices determined in the determination process are synchronized with each other.

According to another aspect of the present invention, there is provided a data transmission method of a communication apparatus in a communication system including a plurality of communication apparatuses, The method comprising the steps of: determining communication devices for simultaneously transmitting data through multiplexing using a plurality of multiplexing methods using a plurality of multiplexing methods; and notifying multiplexing of different methods used for the multiplexing of data to the communication devices determined in the determining step Process.

Other features of the present invention will be apparent from the following description of exemplary embodiments with reference to the accompanying drawings.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. On the other hand, in the present embodiment, a multi-data transmission technique using different polarizations, signs or frequencies is applied as a type (multiplexing of different methods) of multiplexing radio waves in a communication system, A method of covering a place with another communication device at the same time will be described.

[First Embodiment]

1 is a diagram showing a configuration example of a network according to the first embodiment. In Fig. 1, reference numerals 101 to 108 are second communication apparatuses (nodes). Reference numeral 110 denotes a first communication apparatus (control station). The control station 110 wirelessly transmits / receives stream data such as a control signal, a video signal, and a voice signal to / from the nodes 101 to 108.

1, the control terminal 110 receives stream data such as a video signal and a voice signal from an external device via a wired cable, and broadcasts the data to a plurality of nodes 101 to 108 in the network. In order to transmit the stream data, an OFDM communication method or the like is used as a high-speed communication method, and a QPSK, 8PSK, or 16QAM communication method is used as a primary modulation method.

OFDM is an abbreviation of Orthogonal Frequency Division Multiplexing (QPSK), quadrature phase shift keying (QPSK), 8PSK is an abbreviation of 8-phase shift keying , And 16QAM is an abbreviation of 16-Quadrature Amplitude Modulation.

The OFDM communication system and the communication system such as QPSK, 8PSK, or 16QAM used as the primary modulation are well known and will not be described in detail.

Nodes 101 - 108 wirelessly transmit / receive control signals and control data to / from control station 110. In addition, each node wirelessly receives stream data such as a video signal from the control terminal 110 and a plurality of other nodes, and wirelessly transmits the received stream data.

After a topology is formed between the control station 110 and the plurality of nodes 101 to 108 so as not to cause a delay in transmitting the stream data, the control station 110 determines the order of time division transmission from each node . Thereafter, each node transmits data in a time slot assigned to each node in the determined transmission order.

Here, the time slot is a period in which each node transmits the stream data. The transmitting node transmits the stream data in a predetermined slot period.

Each node performs redundant transmission by sequentially transmitting the received stream data to another node in the order determined by the control station 110. [ Each node selects the most reliable data from the same stream data received a plurality of times, and performs video display and audio signal reproduction.

As described above, the stream data is transmitted without a transmission delay after the topology is formed between the control terminal 110 and the plurality of nodes 101 to 108.

However, in order to form such a topology, it is necessary for each node to reliably receive control data transmitted from the control terminal 110, such as transmission order of each node, multiplexing in a different method of transmission, and reception wave type of each node have. Therefore, the control data is transmitted using a highly reliable communication method using the RTS (Request to Send) / CTS (Clear to Send) method. On the other hand, since the communication method using the RTS / CTS method is a well-known technology, a detailed description will be omitted.

Further, as a carrier modulation method, data transmission is reliably performed using a low-speed data transmission method having noise immunity to some extent, such as DBPSK (Differential Binary Phase Shift Keying). Here, DBPSK is a well-known technology, as evidenced by the IEEE802.11 standards of wireless LAN, and therefore, the description thereof is omitted. Details of a method for determining the transmission order from each node of the control terminal 110 will be described later.

Next, a case is described in which all the nodes can receive data by transmitting the stream data at the slot timing four times after the control station 110 first transmits the original stream data. Each node has a specific antenna directivity and broadcasts stream data to other nodes. Fig. 2 is a diagram schematically showing the antenna directivity of the node 101. Fig. On the other hand, it is assumed that the other nodes 102 to 108 and the control station 110 also have the same antenna directivity as the node 101. [

3 is a diagram schematically showing a shadow area obtained when the node 101 and the node 104 simultaneously transmit data using different polarizations. In Fig. 3, since the node 101 has only the antenna directivity 201 shown in Fig. 2, there is a place where the radio wave does not reach and a place where the radio wave intensity is weak. Further, irrespective of the antenna directivity, in a place where the received signal strength is low and at a position far from the node at the time of the transmission operation, since the radio wave is weak, a place where communication is impossible is formed. These areas are collectively referred to as a shadow area 301.

In Fig. 3, when the node 101 transmits stream data, other nodes in the shadow area 301 can not communicate with the node 101. Fig. For example, in FIG. 3, when the node 101 and the node 104 attempt to transmit data as shown in FIG. 3, the node 106 arranged in the shadow region 301 can not communicate with the node 101. Further, the node 102 arranged in the shadow area 302 caused by the arrangement of the node 104 can not communicate with the node 104. [ In addition, there is a possibility that the node 101 can not communicate with the node 108 remote from the node 101, and the same applies to the relationship between the node 104 and the node 107. Therefore, redundant transmission of stream data is performed by using different polarizations by different nodes.

4 is a block diagram showing an example of the internal configuration of the control station 110. As shown in Fig. 4, the control station 110 includes a wireless communication unit 401, a polarization type control unit 402, a control unit 403, a memory 404, a slot timing generating unit 405, 406). The control station 110 further includes a system control processing unit 407, an external interface 408, an antenna 410 for transmitting and receiving vertically polarized waves, and an antenna 411 for transmitting and receiving horizontal polarized waves.

In the above configuration, the control unit 403 transmits the control data to the wireless communication unit 401, the wireless communication unit 401 modulates the control data into wireless signals, and then, these signals are transmitted from the antennas 410 and 411 do.

External data 409 such as a video signal and a voice signal captured by the external interface 408 are temporarily stored in the memory 404. Then, in accordance with the instruction from the control unit 403, the data is sent to the radio communication unit 401 in synchronization with the slot timing generated by the slot timing generation unit 405. [ Here, the slot timing is a timing at which each node sequentially transmits data. The radio communication unit 401 modulates the received external data into a radio signal, and then wirelessly transmits this signal from the antenna 410 or 411 according to the slot timing.

The control unit 403 controls the entire operation of the control station 110 and controls the wireless communication unit 401 to transmit data at the slot timing for controlling synchronization of wireless communication with other nodes. In addition, the control unit 403 frames the transmission data based on the terminal information transmitted as control data from another node. The control station 110 transmits data (hereinafter, "frame data") framed in one communication to each node, and transmits frame data redundantly between the nodes.

The wireless communication unit 401 communicates with the plurality of nodes 101 to 108 through two types of polarizations that are orthogonal to each other in accordance with an instruction from the control unit 403 and outputs a signal for each polarization type transmitted from each node to the control station 110 To the link quality determining unit 406. [

The link quality determining unit 406 measures the received signal strength, bit error rate, or frame error rate of each signal transmitted from the plurality of nodes 101 to 108, quantifies the measurement result, and transmits it as link quality to the system control processing unit 407 do. Here, the link quality refers to the link signal quality, the bit error rate, or the frame error rate of each signal transmitted from each node to the control station 110 at the time of communication between the control terminal 110 and the plurality of nodes 101 to 108 It is a value obtained based on the measurement result.

The system control processing unit 407 lists the link quality of each node, creates a connection list, and transfers the list to the memory 404; And stores the connection list in the memory 404. Each node also creates a connection list like control station 110; The wireless communication unit 401 receives the connection list created between the nodes based on the polarization type from each node and stores the connection list in the memory 404.

The system control processing unit 407 refers to the connection list in the memory 404, determines the transmission order of the transmitting node, and transmits the node to the transmitting node .

The memory 404 stores a threshold value of a predetermined link quality used for determining the transmission order from the transmitting node.

The system control processing unit 407 sends the data of the transmission order from each determined node to the control unit 403 and the control unit 403 sends the transmission order data to the wireless communication unit 401. [ Thereafter, the wireless communication unit 401 transmits the transmission order data to each node in accordance with the timing generated by the slot timing generation unit 405. [

The polarized wave type control unit 402 switches between the antenna 410 and the antenna 411 at the slot timing generated by the slot timing generation unit 405 in accordance with an instruction from the control unit 403. [

Fig. 5 is a block diagram showing an example of the internal configuration of the node 101. Fig. On the other hand, since the internal configuration of the nodes 102 to 108 is also the same as that of the node 101, the operation will be described taking the node 101 as an example.

5, the node 101 includes a wireless communication unit 501, a polarization type control unit 502, a control unit 503, a memory 504, a slot timing generation unit 505, a link quality determination unit 506, Respectively. The node 101 further includes a data processing unit 507, an antenna 508 for transmitting and receiving vertically polarized waves, and an antenna 509 for transmitting and receiving horizontal polarized waves.

In the above configuration, the wireless communication unit 501 sends the received stream data to the memory 504. The polarization type control unit 502 switches the antenna 508 and the antenna 509 at the slot timing generated by the slot timing generation unit 505 in response to an instruction from the control unit 503 at the time of data transmission and reception.

The control unit 503 selects the data of its own node 101 from the received data accumulated in the memory 504 and the data processing unit 507 decodes the selected data and outputs the decoded data 510. Video display or audio reproduction is performed based on the video and audio data 510 decoded by the data processing unit 507. [

The received data accumulated in the memory 504 is transmitted to the wireless communication unit 501 in response to an instruction from the control unit 503 and is then wirelessly transmitted at a timing generated by the slot timing generating unit 505. [

The wireless communication unit 501 also communicates with the other nodes 102 to 108 and the control station 110 which are two polarizations that are orthogonal to each other in accordance with an instruction from the control unit 503, And sends it to the link quality judgment unit 506. The link quality judgment unit 506 measures the received signal strength of the received signal, the bit error rate or the frame error rate, and then sends the result of the measurement to the data processing unit 507 as the link quality.

The data processing unit 507 lists the link quality of each node, creates a connection list, and stores the contents of the list in the memory 504; The memory 504 stores the contents of the list.

The wireless communication unit 501 transmits a connection list created based on their polarization types between the other nodes 102 to 108 and the control station 110 to the other nodes 102 to 108 and the control station 110, And stores the contents of the list in the memory 504. [

6A to 6C are diagrams showing an example of a connection list showing not only the nodes 101 to 108 but also the relationship between each node and the control station 110. Fig. 6A to 6C provide connection lists created at node 101, node 102, and node 104. Although only three types of connection lists are shown in these drawings, a list of connections created by the other five nodes and the control station 110 is also created. In addition, H denotes horizontal polarization, and V denotes vertical polarization.

As shown in Figs. 6A to 6C, the connection list includes a node name 601, a polarized wave 602 indicating a polarization multiplex type to be used, a link quality 603 between the node itself and the control station ). This link quality 603 is the link quality received by one of the nodes from the other node and the control station 110. For example, according to the connection list of the node 101 shown in Fig. 6A, the node 101 receives the signal transmitted by the control terminal 110 in the column of node name 601 using the vertical polarization as the polarization 602 In this case, the link quality 603 is " 8 ".

7 is a diagram showing time slots in which the control terminal 110 and each of the nodes 101 to 108 transmit data. 7, reference numeral 710 denotes data transmitted by the control terminal 110, and reference numerals 701 to 708 denote data transmitted by the nodes 101 to 108. In FIG. Reference numeral 711 denotes a period for each of the nodes 101 to 108 and the control terminal 110 to switch antennas during transmission and reception.

A period in which a plurality of time slots T1 to T6 in which the nodes 101 to 108 redundantly transmit the stream data transmitted once from the control terminal 110 is referred to as a redundant frame. In the first embodiment, one redundant frame is composed of two time slots T1 and T2 for which the control station 110 transmits data and four time slots T3 to T6 for which each node 101 to 108 transmits data .

In the communication system according to the present invention, redundant transmission of stream data such as video data and audio data in one redundant frame is performed. The control station 110 and the plurality of nodes 101 to 108 control the switching of the antennas according to the polarized waves transmitted and received during the period 711.

In Fig. 7, the control station 110 transmits data using horizontal polarization in time slot T1, and transmits data using vertical polarization in time slot T2. Further, the upper and lower ends in time slots T3 to T6 indicate that the nodes transmit at the same time using different polarizations. For example, in timeslot T3, node 101 transmits data 701 and node 104 transmits data 704.

In the following description, time slots starting from time slot T3 in which the control terminal 110 transmits stream data are referred to as a first slot, a second slot, ... , And the nth slot.

After the stream data is transmitted from the control station 110 to the horizontal polarized wave and the vertical polarized wave, the nodes 101 and 104 simultaneously transmit data using the different polarized waves in the first slot. Nodes 101 and 104 can reliably receive data from control station 110 and node 101 has the best link quality to control station 110. [ In addition, the nodes other than the nodes 101 and 104 are in the reception state, that is, receive the polarization data set by the control station 110. [ On the other hand, a method of selecting a node to be simultaneously transmitted will be described later.

Next, nodes 105 and 102 transmit simultaneously in the second slot. Thereafter, according to the transmission order determined by the control terminal 110, sequentially in each time slot, specific nodes transmit data at the same time.

8 is a flowchart showing a process for determining the transmission order from the plurality of nodes 101 to 108 at the control terminal 110. Fig. 9 is a diagram showing a sequence for determining the transmission order from the plurality of nodes 101 to 108 performed in the control station 110. As shown in Fig.

In addition to the plurality of nodes 101 to 108, each node and the control station 110 communicate with each other, so that the link quality determining sections 506 and 406 determine their link quality (S801, 901). Thereafter, the system control processing unit 407 of the control terminal 110 and the data processing unit 507 of each of the nodes 101 to 108 create respective connection lists (S802, 902). The nodes 101 to 108 and the control station 110 share the connection list by performing communication with each other (S803, 903, and 904) and store them in their memory (905).

At this time, since a topology has not yet been formed between each node and the control station 110, a highly reliable communication method using the above-described RTS / CTS scheme is used in order to reliably share data.

The control station 110 determines the transmission order from each node based on the connection list concerning all the nodes 101-108 and the control station 110 itself. The system control processing unit 407 of the control station 110 selects a node having a high link quality for the control station 110 itself based on the connection list as a transmitting node; The transmitting node selected by this process is referred to as a node a1 (S804, 906).

Further, node a2 to be transmitted is selected in the next time slot. A node capable of reliably receiving data in addition to the node a1 and the control station transmitted in the previous time slot is selected as the node a2 to be transmitted in the next time slot and the node farthest from the control station 110 is selected. At this time, in order to determine whether communication with the control station 110 can be reliably performed, a threshold value of the link quality existing in the connection list is set in advance.

Specifically, based on the error occurrence rate of the received data and the error correction rate of the error correcting code of the data, the link quality that can accurately decode the data is determined when communication is performed between the nodes, The threshold value is set. In this case, the threshold value of the link quality that can correctly decode the received data is set to " 7 ".

The nodes that transmit in the following time slots are also selected using the above method. Herein, the node a1, the node a2, and the transmission node selected by the subsequent selection process are collectively referred to as a node a group.

Next, in each time slot, the node b group to be simultaneously transmitted is selected using the polarizations different from those used by the node a group (S805, 907). After selecting the node a group and the node b group for transmitting data, the system control processing unit 407 of the control station 110 determines the polarization type used by each node receiving the data (S806, 908). At this time, the control station 110 refers to the connection list of each receiving node, compares the secured link quality when the node a group and the node b group transmit data using the predetermined transmission polarized wave, , And determines the polarization type that is the same as the better transmission polarization type as the reception polarization type.

On the other hand, a method of selecting the node b group will be described later. For the sake of convenience, hereinafter, the respective processing steps of the flowchart shown in Fig. 8 are collectively referred to as training.

Next, a first method of selecting a node b group to be transmitted simultaneously with the node a group using a polarization different from that used by the node a group will be described. The second method for selecting the node b group will be described in the second embodiment.

10 is a flowchart showing a method of selecting a group of nodes b to be transmitted at the same time using different polarizations according to the first embodiment. 11A to 11C are diagrams showing a list used for selecting a node b group according to the first embodiment. 11A to 11C, the same reference numerals are attached to the respective constituent elements as those shown in the connection list of Figs. 6A to 6C.

Before describing the method of selecting the node b group, a method of selecting the node a group using the connection list shown in Figs. 11A to 11C will be described. First, since node a1 has the best link quality to the control station 110, attention is paid to the link quality of each node with respect to the control station 110. [ In the example shown in Figs. 11A to 11C, considering the combination of the node and the polarized wave that exhibits the best link quality based on the reference numerals 1101 to 1103, the combination of the node 101 and the control station 110 using the vertical polarization is the best link Quot; 8 ", the node 101 is selected as the node a1.

Next, a method of selecting the node b group will be described with reference to Figs. 10 and 11A to 11C. First, a process of selecting a node a1 transmitting in the first slot and a node b1 transmitting simultaneously will be described with reference to Fig.

The control station 110 refers to the connection list of the selected transmission node a1 by using the above-described method. On the other hand, in Fig. 10, node a1 corresponds to node 101 using vertical polarization (V). In addition, " n " shown in Fig. 10 indicates a transmission order of time slots. In the following description, attention will be given to selection of a node to be transmitted in the first timeslot, and for convenience of explanation, "n" is referred to as "1" indicating the first transmission sequence.

Next, the control terminal 110 selects the node p1 having the worst link quality through the connection list of the node a1 (S1001); The node p1 has the worst link quality with respect to the polarization transmitted from the node a1. This processing will be described with reference to Figs. 11A to 11C.

Here, in order to select the node p1, attention is paid to the connection list of the node 101 as the node a1. That is, since the node 101 transmits using the vertically polarized wave V, the node p1 becomes the node 106 (1104) having the worst link quality among the nodes using the vertically polarized wave V of FIG. 11A.

Next, the control station 110 selects a node from which it can reliably receive data from the control station 110, indicating that the link quality is equal to or higher than the threshold value from the connection list of each node except for the node a1 (S1002 ). Then, the node having the best link quality for the node p1 is selected from the selected node (S1003). At this time, the selected node is a node that transmits using a polarization different from that used by the node a1. The selected node is used as a node b1 transmitting simultaneously with the polarized wave path a1 different from that used by the node a1 (S1004). This operation will be described with reference to Figs. 11A to 11C.

11A to 11C, the node 106 is used as the node p1. In addition, since the node 101 as the node a1 transmits data with the vertical polarization (V), the node b1 needs to transmit data with the horizontal polarization H.

In order to select the node with the best link quality for the node 106 under this condition, attention is paid to the link quality when the node other than the node 101 transmits to the node 106 with the horizontal polarization (H). 11A-11C, the link quality between node 102 and node 106 is " 5 " as indicated by reference numeral 1105, and the link quality between node 104 and node 106 is indicated by reference numeral 1106 Quot; 8 "

In addition, since the selected node needs to reliably receive data from the control terminal 110, it is necessary to check the level of link quality with respect to the control terminal 110. [ That is, the link quality between the node 102 and the control station 110 indicated by reference numeral 1102 is " 6 " when the horizontal polarization is used and is " 4 " On the other hand, the link quality between the node 104 indicated by reference numeral 1103 and the control station 110 is " 7 " when horizontal polarization is used and is " 6 " The node 102 can not correctly receive data from the control terminal 110 because the threshold of the link quality level capable of decoding the received data is "7 ". On the other hand, the node 104 can correctly receive data transmitted from the control terminal 110 using the horizontal polarization.

From the above operation, it can be seen that the node 104 has the best link quality to the node 106 and can correctly receive data from the control station 110. [ Node 102 can not correctly receive data from control station 110 and is also less than node 104 in link quality to node 106. [ Therefore, the node 104 is selected as the node b1.

Although the method of selecting the node b1 has been described above, such a method is also used for the node b2 to be transmitted simultaneously with the transmission by the node a2 and the node bn to be transmitted in the subsequent time slot. The above is a description of the training including a method of selecting the node b.

Next, a series of procedures and operations including the training performed by the control station and each node until the control station 110 and each of the nodes 101 to 108 complete data transmission will be described.

12 is a flowchart showing an operation performed by a plurality of nodes and control stations until a plurality of nodes 101 to 108 and control station 110 have completed data transmission. In Fig. 12, " m " is the number of transmission of the redundant frame. The communication system transmits stream data using a redundant frame. The control terminal 110 divides stream data from the external interface 408 into a plurality of frame data and transmits the divided data.

13 is a diagram showing an operation sequence performed by a plurality of nodes and a control station until a plurality of nodes 101 to 108 and control station 110 have completed data transmission. 14 is a diagram showing a list of transmission polarized wave types and reception polarized wave types used by each node in a plurality of time slots obtained as a result of training.

First, the plurality of nodes 101 to 108 and the control station 110 perform the above-described training (S1201, 1301). As a result of the training, a node a group that sequentially transmits in the first to fourth time slots as the transmission order from each node and a node b group that transmits simultaneously with transmission by the node a group are selected, And also determines the reception polarization type used by the node on the reception side in the slot.

Hereinafter, the transmission order from the transmitting node in each time slot determined by the training, the transmission polarized wave type used by the transmitting node, and the information about the receiving polarized wave type used by each receiving node are collectively referred to as & Result ". This training result is list-type control data, as shown in Fig. 14, only the training results of the first and second time slots are shown; Although not shown in the figure, the training results in the third and fourth time slots are also made in a list.

The list of training results is composed of a node name 1401, a transmission polarized wave 1402 used by each node, and a reception polarized wave 1403 used by each node; Each node transmits and receives in each time slot with a predetermined polarization as shown in the list of the training results.

Next, the control terminal 110 notifies each node of the above training results (S1202, 1302). At this time, since the topology of the communication system is not yet formed, the transmission order information from each node is transmitted using the same transmission method as that used when the link quality list is shared.

Each node judges from the notification of the training result that the control terminal 110 first transmits the stream data with the horizontal polarization, and switches the two antennas to receive the horizontal polarization (S1203, 1303). The control station 110 transmits the stream data with the horizontal polarization, while each node receives the stream data with the horizontal polarization (S1204, 1304).

Next, each node switches to an antenna capable of receiving vertical polarization based on the above training results (S1205, 1305). Then, the control terminal 110 transmits the stream data with the vertical polarization, and each node receives the stream data with the vertical polarization (S1206, 1306).

Next, after the transmission of the stream data from the control terminal 110 is finished, each node switches antennas based on the training results (S1207, 1307). The node 101 transmits vertically polarized wave data, and the node 104 transmits horizontal polarized wave data to the shadow region generated in the arrangement of the node 101 (S1208, 1308, and 1309). On the other hand, other nodes receive data from the node 101 or the node 104 transmitted from the control terminal 110 using a specific polarization based on the training result transmitted from the control terminal 110. [

Thereafter, as in the case of the operation performed in the time slot, specific two nodes transmit data based on the transmission order data transmitted from the control terminal 110, and the other reception side nodes transmit data to either one of the two nodes Lt; RTI ID = 0.0 > polarized wave < / RTI > On the other hand, these operations are included in the flowcharts as S1209 to S1214 and 1310 to 1318.

After transmission and reception of data by the control station 110 and the plurality of nodes 101 to 108 is completed in all time slots in one redundant frame, the number of redundant frames "m" is incremented (S1215). If the number of transmitted redundant frames " m " is equal to the number of divided frame data of the stream data (YES in S1216), the data transmission is terminated. On the other hand, if they are different (NO in S1216), since the transmission of the stream data has not yet been completed, the process returns to S1203, the transmission order in each time slot is maintained, and the data of the next redundant frame is transmitted.

Until now, data transmission has been performed redundantly until all nodes can receive radio waves without multiplexing the radio waves. Compared with such conventional transmission, in the first embodiment, the number of nodes capable of correctly receiving stream data in four time slots after transmission of original stream data from the control terminal 110 is surely increased The reliability can be increased with a small number of communication times.

Further, by using the method of the embodiment in which different nodes simultaneously transmit different polarized wave data to a shadow region generated by the arrangement of one transmitting node, redundancy is reduced as compared with the conventional transmission method, Can be doubled.

[Second Embodiment]

Next, a second embodiment of the present invention will be described in detail with reference to the drawings. In the second embodiment, a method of selecting a node b group different from the first embodiment will be described.

Fig. 15 is a flowchart showing a method of the first embodiment for selecting a group b of nodes transmitting simultaneously with different polarizations. 16A to 16D are views showing an example of a connection list used for selecting a node b group according to the second embodiment. On the other hand, the order in which each node transmits data in each time slot based on the selection method of the node a group, the order of training, and the training result is the same as that described in the first embodiment.

The control station 110 refers to the connection list of the selected transmitting-side node a1 by using the same method as that of the first embodiment. On the other hand, as in the first embodiment, in Fig. 15, the node al corresponds to the node 101 using the vertically polarized wave (V).

Next, the control terminal 110 selects the node p having the worst link quality with reference to the connection list of the node a1 (S1501); However, the node p is the worst link quality for the polarization transmitted from the node a1. Hereinafter, this operation will be described using Figs. 16A to 16D.

Here, in order to select the node p, attention is paid to the connection list of the node 101 as the node a1. Namely, since the node 101 transmits with the vertical polarization (V), the node p becomes the node 106 (1611) having the worst link quality among the nodes using the vertically polarized wave V of FIG. 16A.

Next, the control terminal 110 performs processing for excluding the node information of the link quality level equal to or less than a predetermined threshold value from the link list of the connection list from the connection list (S1502). First, the threshold value of the minimum link quality required for communication between each node is set to " 7 ". Next, the information of the node whose link quality level is equal to or smaller than the threshold value " 7 " is excluded from the connection list (reference numerals 1602 to 1608 shown in Figs. 16A to 16D).

After that, the control station 110 selects the node (s) capable of communicating with the node p and reliably receiving data from the control station 110 from the connection list excluded in S1502 (S1503) . At this time, the selected node is a node transmitting with a polarization different from that used by the node a1.

In addition, the control terminal 110 determines how many nodes have been selected (S1504). Here, if there is one selected node, the node is selected as the node b (S1507).

On the other hand, when there are a plurality of selected nodes, the number of connectable nodes is counted using the selected connection list of each node (S1505). That is, only the number of nodes connectable by polarization different from that used by the node a1 is counted. Then, the number of connectable nodes is compared with a plurality of selected nodes, and a node having the largest number of connectable nodes is selected as the node b (S1506). This operation will be described using Figs. 16A to 16D.

16A to 16D, node 106 is used as node p. Further, since the node 101 as the node a1 transmits with the vertical polarization (V), the node b needs to transmit with the horizontal polarization H.

Note that in order to select a node capable of communicating with the node 106 under this condition, the link quality displayed when the node other than the node 101 transmits to the node 106 with the horizontal polarization (H). From the connection list shown in Figs. 16A-16D, it can be seen that the node 102 in Fig. 16B is able to communicate with the node 106, but since the link quality for the control station 110 is excluded, . In contrast, nodes 104 and 105 in Figs. 16C and 16D are capable of communicating with node 106 as well as control station 110 (see refs 1609 and 1610).

Thus, node 104 and node 105 are selected as nodes capable of being transmitted to node 106.

Next, node b is selected from the selected nodes 104 and 105. Concretely, attention is paid to the connection list of nodes 104 and 105; The number of nodes connectable to the node 104 and the number of nodes connectable to the node 105 are counted. Here, since the node b transmits the horizontal polarized wave, only the nodes connectable when the horizontal polarized wave is transmitted are counted.

In the node 104, the number of connectable nodes is one except the control station 110 and the node 106 (node 103 indicated by reference numeral 1612). In the node 105, the number is zero except for the control station 110 and the node 106. [ From this result, since node 104 can know that node 103 as well as node 106 can cover, node 104 is selected as node b.

The method for selecting the node b has been described above. However, the method for selecting the node b is selected using the method as described above for the node b transmitting simultaneously with the node a and the node b transmitting in the subsequent time slot.

In the first embodiment, a method of reliably covering only the node p group in the shadow area caused by the arrangement of the node a group when the node b group is selected is proposed. However, in the second embodiment, A node that can not accurately receive a node can be covered. Therefore, the reliability of data transmission can be improved with a smaller number of communication times.

[Third Embodiment]

Next, a third embodiment according to the present invention will be described in detail with reference to the drawings. In the first and second embodiments, a case where two different nodes are transmitted by using different methods, for example, polarization is described. In the third embodiment, a case where two or more nodes transmit data at the same time using a plurality of frequencies is described as a multiplexing method of a different method.

17 is a diagram showing a configuration example of a network according to the third embodiment. In the third embodiment, three transmitting nodes perform multiple data transmission using frequencies as multiplexing in different methods. In this embodiment, three nodes 101, 104, and 102 transmit data at the same time using different frequencies f1, f2, and f3. Reference numerals 1701 to 1703 denote shadow areas when stream data is transmitted from each node, as in the first embodiment.

On the other hand, the configurations of the control terminal 110 and the plurality of nodes 101 to 108 in the third embodiment are the same as those in the first embodiment described with reference to Figs. 4 and 5, and a description thereof will be omitted.

In the first and second embodiments, the different polarizations are realized by switching the antenna type. However, in the third embodiment, the wireless communication units 401 and 501 switch the frequencies of the local signals and transmit / .

18 is a diagram showing time slots in which the control station 110 and each of the nodes 101 to 108 transmit data. The control station 110 transmits data at three different frequencies f1, f2 and f3 to all the nodes 101 to 108 in the time slots T1 to T3. Next, in the time slot T4, the node 101 transmits data at the frequency f1, the node 104 transmits the data at the frequency f2, and the node 102 simultaneously transmits the data at the frequency f3. Even in the subsequent time slots T5 and T6, the three nodes transmit data at the same time without repeating each combination of the transmission frequency and the node.

Next, a method of selecting three nodes for transmitting data using different frequencies at the same time will be described with reference to Fig. Fig. 19 is a flowchart showing a method of selecting nodes to be simultaneously transmitted in the third embodiment. Fig.

In this embodiment, the connection list necessary for selecting three nodes to be transmitted at the same time is created using the same procedure as described in the first embodiment, except that frequency is used instead of polarization as a multiplexing method of the different methods. In addition, since the transmitting-side node is selected using the method as described in the second embodiment, detailed description of the selection using the connection list is omitted here. It is also assumed that the transmitting node transmits in the order shown in Fig.

In the third embodiment, a selection method of the node b group and a selection method of the node c group that transmit data at the same time as the node a group transmitting data will be described. On the other hand, after transmitting data from the control station 110, the node a1 transmitting in the first slot refers to the connection list of each node and the control station 110 as in the first and second embodiments It is the node with the best link quality selected. The node a2 transmitting after the second time slot is a node that can reliably receive data from nodes other than the node and the control station transmitted in the previous time slot and is also the farthest node in the control station. The node a to be transmitted in the subsequent time slot is also selected in the same manner as described above. Here, " n " indicates the order of nodes that transmit data as in the first embodiment.

First, the control terminal 110 selects the node p1 having the worst link quality with reference to the connection list of the selected transmitting node a1 (S1901). At this time, since the node 101 as the node al in Fig. 18 uses the frequency f1, the node p1 is selected based on the link quality with respect to the frequency f1.

Next, the control terminal 110 sets a threshold of the link quality indicated in the connection list, and excludes the node information of the link quality lower than the threshold value from the connection list (S1902). At this time, the threshold value is set to a level of link quality that can reliably decode data when communication is performed between the nodes. Then, the control terminal 110 selects the node (s) capable of communicating with the node 1 based on frequencies other than the frequency f1 used by the node a1 presented in the exclusion-processed connection list in S1902 (S1903).

Next, the control terminal 110 determines how many nodes have been selected (S1904). At this time, when there is one selected node, the node is referred to as a node b1.

On the other hand, when there are a plurality of selected nodes, the number of connectable nodes is counted by using the connection list of each selected node (S1905); Only the number of nodes connectable at frequencies f2 and f3 different from the frequency f1 used by the node a1 is counted.

Next, the number of connectable nodes is compared with each selected node, and the node with the largest connectable number is selected as the node b1 (S1906). On the other hand, in the example shown in Fig. 18, the node b1 is the node 104, and transmits data using the frequency f2.

In the third embodiment, since three nodes can be selected to transmit at the same time, in order to further cover the shadow area in the node a1 and the node b1, the operation of the node c1 . However, when there is no shadow area between the node a1 and the node b1, since there is no need to select the node c1, there are two nodes to transmit.

Next, it is determined whether or not there is a node that can not correctly receive data from the node a1 and the node b1 (S1907). Herein, a node in the shadow area of the nodes a1 and b1 is referred to as a node q1.

As a result of the determination, if there is a node q1, the control terminal 110 refers to the connection list and selects a node having a good link quality with respect to the node q1 (S1908). Here, when there is one selected node, the node is referred to as a node c1.

On the other hand, when there are a plurality of selected nodes, the number of nodes connectable to each selected node is counted by using the connection list of each selected node; Here, only the number of nodes connectable at the frequency f3 different from that used by the nodes a1 and b1 is counted.

Thereafter, the number of connectable nodes is compared with each selected node, and a node with the largest connectable number is selected as the node c1 (S1909). In the example shown in Fig. 18, the node c1 is the node 102, and transmits data using the frequency f3.

Also, nodes b2 and c2 transmitting simultaneously with node a2, as well as nodes bn and cn transmitting in time slots thereafter are selected in the same manner as described above.

The above is a node selection method used when three nodes perform simultaneous transmission.

Next, a series of procedures and operations including the control station and the training performed by each node until each node completes the data transmission will be described.

20 is a flowchart showing an operation performed by the control station and each node until the control station and each node in the third embodiment complete data transmission. 21 is a diagram showing a sequence of operations performed by the control station and each node until the control station and each node in the third embodiment complete data transmission.

First, the plurality of nodes 101 to 108 and the control station 110 perform training (S2001, 2101). The control station 110 notifies each node 101 to 108 of the training results using the same transmission method as that in the case of sharing the link quality list in the first embodiment (S2002, 2102).

Each node determines the frequency to be received based on the training result, and sets the frequency of the local signal (S2003, 2103).

The control station 110 transmits the stream data at the frequency f1 (S2004, 2104). During the transmission, each node receives its stream data. Next, each node sets the frequency of the local signal (S2005, 2105), and the control terminal 110 transmits the stream data at the frequency f2, and each node receives the stream data (S2006, 2106). Further, each node sets the frequency of the local signal (S2007, 2107), the control station 110 transmits the stream data at the frequency f3, and then each node receives the stream data (S2008, 2108).

After the transmission of the stream data from the control station 110 is completed, each node sets the frequency of the local signal based on the training result (S2009, 2109). Then, the node 101 transmits the data at the frequency f1, and the node 104 transmits the data at the frequency f2 to the shadow area generated by the arrangement of the node 101. [ In addition, the node 102 transmits data at the frequency f3 to the shadow area generated by the arrangement of the nodes 101 and 104 (S2010 and 2110). The other node receives data from one of the nodes 101, 104, and 102 at a specific frequency based on the transmission order data transmitted from the control terminal 110.

In the subsequent time slots, similarly, three specific nodes transmit data based on the transmission order data transmitted from the control station 110. [ The other receiving node receives data at a specific frequency from one of the three nodes (S2011 to S2014, 2111 to 2114).

After transmission and reception of data by the control station 110 and the nodes 101 to 108 is completed in all time slots in each redundant frame, the number m of redundant frames is incremented by one (S2015). In S2016, if the number m of the transmitted redundant frames is equal to the number of divided frames of the stream data, the data transmission is terminated. On the other hand, since the transmission of the stream data is not completed in the different case, the process returns to the step S2003, the transmission order in each time slot is maintained, and the data is transmitted in the next redundant frame.

In the third embodiment, three nodes transmit data at the same time using different frequencies, and a shadow region generated when two nodes transmit data at the same time in the first or second embodiment is referred to as three nodes It is possible to cover data transmission from other nodes at the same time. Therefore, the reliability of data transmission can be further improved with a smaller number of communication times.

[Other Embodiments]

In the first to third embodiments, the type of polarization or frequency received by each node is determined by the control station based on the training results, but the polarization or frequency to be received may be determined by each node. That is, since each node shares the connection list, when the name of the control station or node to be transmitted is notified, it is possible for the node of its own to select the transmitting node having good link quality based on the connection list.

As a result, since each node determines the type of polarization that each node receives, it is possible to reduce the amount of data required to notify a training result as compared with the above-described embodiment.

In the first to third embodiments, polarization and frequency are used as multiplexing in different methods. However, multiplexing of different methods is used for a code system represented by a code division multiple access (CDMA) system Code may be used, or a combination thereof may be used. On the other hand, since the CDMA scheme is a well-known technique, detailed description is not given here.

Regarding polarized waves, there are polarized waves orthogonal to each other without interfering with each other, as well as vertical polarized waves and horizontal polarized waves, as well as right polarized waves and left polarized waves. When a code is used, a code having a low cross-correlation is used. Further, when frequencies are used, different frequency bands are used.

Thus, by using multiplexing in a variety of different ways, a flexible communication system responsive to the propagation environment can be constructed. In other words, by using different methods of multiplexing, it is possible to flexibly cope with various communication interferences. With respect to the use of polarized waves, horizontal and vertical polarizations are used in the first and second embodiments. However, by using the right polarizations and the left polarizations, the use of multipath The influence can be reduced. On the other hand, a technology capable of reducing the influence of multipath by using right and left polarizations is a well-known technology, and therefore, detailed description thereof will not be given here.

In addition, three or more nodes may be transmitted in one data communication. On the other hand, when two or more nodes transmit data at the same time, nodes are selected using the same algorithm as the method of selecting the transmitting node described in the third embodiment.

By using this method, it is possible to improve the reliability of data transmission with a smaller number of communications, compared with the reliability achieved in the above-described embodiment.

In the embodiments described above, the antenna directivity is limited to the transmitting antenna, but the case where the receiving antenna has the specific antenna directivity is also effective.

According to the embodiments described above, in a communication system that performs redundant data transmission, one or more nodes can simultaneously transmit data to other receiving nodes. Therefore, each node can receive data accurately with a small number of communications as compared with a conventional node. In addition, when polarization is used as a multiplexing in different methods, the efficiency of use of the communication channel can be increased.

Incidentally, the present invention can be applied not only to a system constituted by a plurality of devices (e.g., a host computer, an interface, a reader, a printer, etc.) but also to a device (e.g., a copying machine, a facsimile apparatus, .

Further, a storage medium storing software program codes for realizing the functions according to the above-described embodiments is supplied to a system or an apparatus, and a computer (CPU or MPU) of the system or the apparatus reads out the program codes stored in the storage medium Then run the program. Needless to say, the object of the present invention is also achieved by this operation.

In this case, the program code itself read from the computer-readable storage medium realizes the function according to the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program codes, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card,

Needless to say, the functions of the above-described embodiments are realized by executing the program read by the computer, and the following cases are also included. In other words, an operating system (OS) or the like running on the computer performs some or all of the actual processing based on the instructions of the program code, and the functions of the above-described embodiments are realized by the processing.

Further, the program code read from the storage medium is recorded in a memory provided in a function expansion board inserted in the computer or a function expansion unit connected to the computer. Thereafter, based on the instruction of the program code, a CPU or the like provided in the function expansion board or the function expansion unit performs a part or all of the actual processing, and the function of the above-described embodiment is realized by the processing Needless to say, it also includes.

Although the present invention has been described with reference to exemplary embodiments, it is not limited to the exemplary embodiments of the present invention. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all modifications, equivalent structures and functions.

1 is a diagram showing a configuration example of a network according to the first embodiment.

Fig. 2 is a diagram schematically showing the antenna directivity at the node 101. Fig.

FIG. 3 is a diagram schematically showing a shadow region that can be used when simultaneous data transmission is performed using different polarizations from the node 101 and the node 104. FIG.

4 is a block diagram showing an example of the internal configuration of the control station 110. As shown in Fig.

5 is a block diagram showing an example of the internal configuration of the node 101. As shown in Fig.

6A to 6C are diagrams showing an example of a connection list shared by each node and the control station 110. Fig.

7 is a diagram showing time slots in which the control terminal 110 and each of the nodes 101 to 108 transmit data.

8 is a flowchart showing a process for determining the transmission order from the plurality of nodes 101 to 108 at the control terminal 110. Fig.

9 is a diagram showing a sequence for determining the transmission order from the plurality of nodes 101 to 108 at the control terminal 110. Fig.

Fig. 10 is a flowchart of a method of selecting a group of nodes b to be transmitted simultaneously with different polarizations according to the first embodiment.

11A to 11C are views showing an example of a connection list used for selecting a node b group according to the first embodiment.

FIG. 12 is a flowchart showing operations performed by the plurality of nodes 101 to 108 and the control station 110 until the plurality of nodes 101 to 108 and the control station 110 complete data transmission.

13 is a diagram showing an operation sequence performed by the plurality of nodes 101 to 108 and the control station 110 until the plurality of nodes 101 to 108 and the control station 110 complete data transmission.

14 is a diagram showing a list of transmission polarized wave types and reception polarized wave types used in time slots obtained as a result of training.

15 is a flowchart showing a method for selecting a group of nodes b to be simultaneously transmitted with different polarizations according to the first embodiment.

16A to 16D are views showing an example of a connection list used for selecting a node b group according to the second embodiment.

17 is a diagram showing a configuration example of a network according to the third embodiment.

18 is a diagram showing time slots in which the control station 110 and each of the nodes 101 to 108 transmit data.

Fig. 19 is a flowchart of a method for selecting a node to be simultaneously transmitted according to the third embodiment.

20 is a flowchart of operations performed by the control station and each node until the control station and each node complete data transmission according to the third embodiment.

Fig. 21 is a view showing an operation sequence of the control station and each node until the control station and each node complete data transmission, according to the third embodiment. Fig.

Claims (19)

A communication system comprising a plurality of communication devices, First determining means for determining, based on the link quality of each communication apparatus, communication apparatuses that simultaneously transmit data through multiple data transmissions using different methods of multiplexing; And transmission means for performing the multiple data transmission according to a timing at which the communication devices determined by the first determination means synchronize with each other. The method according to claim 1, Wherein the link quality is based on a received signal strength, a bit error rate, or a frame error rate, which is obtained by each communication apparatus when the multiplex data transmission is performed using two types of mutually orthogonal multiplexing. The method according to claim 1, Wherein the first determining means determines whether or not a communication device having a link quality equal to or higher than a threshold value of link quality of communication devices with poor link quality to the first communication device As a communication device. The method according to claim 1, Wherein when the third communication apparatus has a link quality that is equal to or higher than a threshold value of link quality of second communication apparatuses with poor link quality for the first communication apparatus, And determines a communication device that performs the multiple data transmission simultaneously with the first communication device, based on the number of communication devices connectable with the devices. The method according to claim 1, Wherein the timing at which the communication devices transmit data is determined based on the link quality. The method according to claim 1, The multiple data transmission using the multiplexing of different methods is any one of multiple data transmission using horizontal polarization and vertical polarization, multiple data transmission using code division multiplexing, and multiple data transmission using frequency division multiplexing Lt; / RTI > The method according to claim 1, And switching means for switching the multiplexing of the different methods according to a predetermined timing, Wherein the transmission means performs the multiple data transmission while the switching means switches the multiplexing of the different methods. The method according to claim 1, Further comprising second determining means for determining multiplexing of the different methods for use in the multiple data transmission. 9. The method of claim 8, Wherein said second determining means determines multiplexing of different methods for use in receiving data transmitted over said multiple data transmissions. 9. The method of claim 8, Wherein the second determining means determines multiplexing of different methods to be used for transmission of data transmitted through the multiple data transmission. 9. The method of claim 8, And switching means for switching the multiplexing of the different methods according to a predetermined timing, And the second determination means determines multiplexing of the different method at the switching timing by the switching means. The method according to claim 1, Wherein the determination by the first determination means is performed by one of the plurality of communication apparatuses. The method according to claim 1, Further comprising measuring means for measuring a link quality of each communication apparatus to other communication apparatuses, Wherein the plurality of communication devices share a result obtained by measuring the link quality for the different communication devices in each different method of multiplexing. The method according to claim 1, Wherein at least some of the plurality of communication devices relay the received data to other communication devices. The method according to claim 1, Further comprising third determining means for determining a relaying order for relaying data, Wherein the transmission means performs the multiple data transmission in the order determined by the third determination means. A communication apparatus in a communication system comprising a plurality of communication apparatuses, Determining means for determining, based on the link quality of each communication apparatus, communication apparatuses that simultaneously transmit data through multiple data transmissions using different methods of multiplexing; And notification means for notifying, to the communication apparatuses determined by the determination means, multiplexing of the different methods used for the multiple data transmission. A data transmission method for use in a communication system comprising a plurality of communication devices, Determining communication devices that simultaneously transmit data through multiple data transmissions using different methods of multiplexing based on link quality of each communication device; And performing the multiple data transmission according to a timing at which the communication devices determined in the determination step are synchronized with each other. A data transmission method of a communication apparatus in a communication system comprising a plurality of communication apparatuses, Determining communication devices that simultaneously transmit data through multiple data transmissions using different methods of multiplexing based on link quality of each communication device; And notifying multiplexing of different methods used for the multiplexing of data for the communication devices determined in the determining step. A computer-readable storage medium storing a program for causing a computer to execute the data transfer method according to claim 18.

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