KR100866801B1 - Uncompressed AV data transferring apparatus - Google Patents

Abstract

The present invention relates to a method and apparatus for improving data transmission efficiency and transmission stability in wirelessly transmitting a large amount of data.

The apparatus for transmitting uncompressed AV data according to an embodiment of the present invention includes a unit for receiving a first superframe from a network coordinator and a frame for requesting a data slot from the network coordinator during the first beacon period to the first superframe. A unit that receives a second superframe including a unit for transmitting to the network coordinator and a data slot allocated from the network coordinator within a second beacon period within a data slot reservation period included and a non-overdone period during a period corresponding to the data slot. And a unit for transmitting compressed AV data to other wireless devices, wherein communication with the network coordinator is via a millimeter wave channel.

Millimeter Wave, Network, Network Coordinator, Time Division, Competition

Description

Uncompressed AV data transferring apparatus

The present invention relates to wireless communication technology, and more particularly, to a method and apparatus for improving data transmission efficiency and transmission stability in wirelessly transmitting a large amount of data.

Networks are becoming wireless and researches on effective transmission methods in wireless network environments have been required due to the increasing demand for large-capacity multimedia data transmission. Due to the nature of a wireless network in which multiple devices share and use a given radio resource, increasing competition is likely to waste valuable radio resources due to collisions during communication. In order to reduce the collision or loss and to transmit and receive data stably, in a wireless LAN (wireless local area network) environment, a competitive-based distributed coordination function (DCF) or a contention-free point coordination function (PCF) In the wireless personal area network (PAN) environment, a time division scheme called channel time allocation is used.

Although such a method can be applied to a wireless network to reduce collisions to some extent and provide stable communication, there is still a high possibility of collision between transmission data compared to a wired network. This is because, in the wireless network environment, there are many factors that prevent stable communication such as multi-path, fading, and interference. In addition, as the number of wireless networks participating in the wireless network increases, the possibility of problems such as collision and loss increases.

Such collisions require retransmissions that have a fatal adverse effect on the throughput of the wireless network. In particular, when better quality of service (QoS) is required, such as audio / video data (AV data), it is very important to secure more available bandwidth by reducing the number of such retransmissions.

Furthermore, given the growing need to wirelessly transfer high-quality video, such as digital video disk (DVD) video and high definition television (HDTV) video, between various home devices, the high-quality video, which requires wide bandwidth, continues to be seamless. There is a need for a technical standard for transmitting and receiving.

Currently, a task group of IEEE 802.15.3c is pursuing a technical specification for transmitting a large amount of data in a wireless home network. This standard, called mmWave (Millimeter Wave), uses radio waves (ie, waves with frequencies of 30 GHz to 300 GHz) whose physical wavelengths are in millimeters for large data transmission. In the past, such a frequency band has been used as an unlicensed band for a limited number of purposes, such as for telecommunication carriers, radio astronomy, or vehicle collision prevention.

1 is a diagram comparing frequency bands between the IEEE 802.11 series standard and mmWave. IEEE 802.11b and IEEE 802.11g have a carrier frequency of 2.4 GHz and a channel bandwidth of about 20 MHz. In addition, IEEE 802.11a and IEEE 802.11n have a carrier frequency of 5 GHz and a channel bandwidth of about 20 MHz. In contrast, mmWave uses a carrier frequency of 60 GHz and has a channel bandwidth of approximately 0.5 to 2.5 GHz. Therefore, mmWave has a much larger carrier frequency and channel bandwidth than the existing IEEE 802.11 standard.

As such, when a high frequency signal (millimeter wave) having a wavelength in millimeters is used, a very high transmission rate in the order of several gigabytes (Gbps) can be represented, and the antenna size can be 1.5 mm or less, so that a single chip including an antenna is used. Can be implemented. In addition, since the attenuation ratio in the air (attenuation ratio) is very high, there is an advantage that can reduce the interference between devices.

On the other hand, due to the high attenuation rate as described above, the communication distance is short, and since the signal is straight, there is a problem that communication is difficult to be properly performed in a non-line-of-sight environment. Therefore, in the mmWave, the former problem is solved by using an array antenna having a high gain, and the latter problem is solved by using a beam steering method.

Recently, in the home and office environment, in addition to the technology of transmitting compressed data using the existing IEEE 802.11 series of G bands, the uncompressed using such millimeter wave in high frequency bands of several tens of G bands. (Uncompressed) A method of transmitting data is introduced. Since the uncompressed data only means that the data is not compressed in terms of lossy coding, lossless coding that can be completely restored may be used.

Since uncompressed AV data is a large amount of uncompressed data, it can be transmitted only in high frequency bands of several tens of bands, and packet loss is relatively insignificant to the display even when compressed data is lost. Therefore, ARQ (Automatic Repeat Request) or Retry may not be performed. Accordingly, there is a need to devise a method for efficiently accessing a medium for efficient transmission of uncompressed AV data transmitted in a high frequency band of tens of gigabytes having the above characteristics.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a method and apparatus for efficiently transmitting uncompressed AV data through a millimeter wave in a tens of GHz band.

Technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

In order to achieve the above technical problem, an uncompressed AV data transmission apparatus includes: a unit for receiving a first superframe from a network coordinator during a first beacon period; A unit for transmitting a frame requesting a data slot to the network coordinator to the network coordinator within a data slot reservation period included in the first superframe; A unit for receiving, during a second beacon period, a second superframe comprising an allocated data slot from the network coordinator; And a unit for transmitting uncompressed AV data to another wireless device during a section corresponding to the data slot, wherein the communication with the network coordinator is performed through a millimeter wave channel.

As described above, according to the present invention, uncompressed AV data can be efficiently transmitted through a millimeter wave of several tens of GHz bands.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention, and the general knowledge in the art to which the present invention pertains. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

2 illustrates a time division scheme according to IEEE 802.15.3. The feature of IEEE 802.15.3 MAC is that the formation of a wireless network is rapid and is based on an ad hoc network called a piconet centered on a iconic coordinator (PNC) rather than an access point (AP). Time intervals for data transmission and reception between devices are arranged in a temporal arrangement structure called a superframe as shown in FIG. 2. The superframe consists of a beacon (12) containing control information, a Contention Access Period (13) section that transmits data through backoff, and a CTAP that sends data without contention in the allocated time. There is a (Channel Time Allocation Period) section. At this time, both the CAP 13 and the MCTA 14 use a competitive approach. Specifically, a carrier sense multiple access / collision avoidance (CSMA / CA) scheme is used in the CAP 13, and a slotted aloha scheme is used in the MCTA.

CTAP 11 is composed of a plurality of channel time allocation (CTA) 15 in addition to the MCTA (14). There are two types of CTA 15: dynamic CTA and pseudo static CTA. Dynamic CTAs can change their location every superframe, and if you miss a beacon, you won't be able to use the CTA in that superframe. In contrast, the pseudo static CTA is fixed at the same position without changing its position, and the CTA section may be used at the fixed position even if the beacon is missed or the superframe is missed. However, pseudo-static CTAs are also prevented from being used if the beacon is missed for more than the same number of mMaxLostBeacons.

As such, IEEE 802.15.3 MAC is based on Time Division Multiple Access (TDMA), which can guarantee stable quality of service (QoS), so multimedia audio / video streaming (A / V streaming), especially on home networks. Suitable for However, there is still room for improvement for transmitting AV data in high frequency bands of tens of gigabytes.

In general, MAC frames transmitted and received between devices on a network are composed of data frames and control frames.

The control frame means all frames that assist in the transmission of the data frame except for the data frame. For example, a control frame may include an association request frame requesting to join a network formed by a network coordinator, and a data slot requesting a data slot for transmitting isochronous data. Data frame request frames, probe request frames for requesting network discovery, coordinator handover request frames that relinquish their role as coordinators, and response frames to them. Also included in the control frame is an acknowledgment (ACK) frame that acknowledges which frame transmission was sent correctly.

However, the size of the data frame and the size of the control frame in IEEE 802.15.3 are not very different. Data frames can be up to 2048 bytes in size and command frames can range from tens to hundreds of bytes in size. However, in order to transmit uncompressed AV data in several tens of GHz bands, the size of the command frame is the same but the size of the data frame is much larger. Therefore, following the conventional IEEE 802.15.3 scheme is inefficient.

In the conventional IEEE 802.15.3 CAP 13 and MCTA 14, various control frames and asynchronous data frames are competitively accessed. In this case, when a relatively low importance asynchronous data frame acquires a channel, the opportunity to transmit a control frame necessary for transmitting uncompressed isochronous data is reduced. In addition, among the control frames, frames related to data slot allocation and frames required for the device to participate in the network are of higher importance than other control frames, but are not competing in the same competition period, and thus, channels cannot be stably obtained. However, if a device misses an opportunity to transmit or receive such important control data, the overall network throughput can be drastically reduced because the opportunity itself to transmit large amounts of uncompressed AV data is blocked.

Therefore, it is necessary to separately arrange a time interval for transmitting a relatively important control frame in the superframe. However, the time interval allocated for this specific control frame is also basically a competition period because a plurality of devices included in the network will have to compete with each other.

3 is a view showing a schematic environment to which the present invention is applied. The network coordinator 100 and at least one device 200a, 200b, 200c constitute one network. The network coordinator 100 broadcasts the superframe periodically during the beacon period. The superframe is included in a beacon signal, and is transmitted to the devices 200a, 200b, and 200c by broadcasting the beacon signal.

Accordingly, the devices 200a, 200b, and 200c may transmit a control frame, a data frame, an ACK, etc. within a contention period or a contention period included in the superframe.

If the device 1 200a, which was not originally included in the network, participates in the network, the association request frame is transmitted to the network coordinator 100 through competition with other devices 200b and 200c during the superframe competition period. (①), and receive a combined response frame therefrom (②).

The association request frame 40 may be configured as shown in FIG. 4. Like all other frames, the combined frame 40 is composed of a MAC header 10 and a payload 20, which includes a control type field 41, a length field 42, and a device address field ( 43), the device information field 44, and the ATP field 45.

The control type field 41 displays an identifier for identifying the control frame, that is, the join request frame 40, and the length field 42 records the total number of bytes of the subsequent fields 43, 44, and 45. do.

In the device address 43 field, a hardware address (eg, a MAC address of up to 8 bytes) of the device 1 200a that transmits the association request frame 40 is recorded. In the device information field 44, various device information such as functions, performances, and capacities of the device 1 200a are recorded. Finally, the Association Timeout Period (ATP) 45 indicates the maximum time that the association relationship can be maintained without communication between the network coordinator 100 and the device 1 200a. This is to re-associate if communication is not performed during the time.

In response to the association request frame 40, the network coordinator 100 transmits the association response frame 50 to the device 1 200a. 5 is a diagram illustrating a configuration of the combined response frame 50. The payload 20 of the combined response frame 50 includes a control type field 51, a length field 52, a device address field 53, a device ID field 54, an ATP field 55, and a code field ( 56).

In the control type field 51, an identifier for identifying the combined response frame 50 is displayed, and in the length field 52, the total number of bytes of the subsequent fields 53, 54, 55, 56 is recorded. The hardware address of the device 1 is recorded in the address 53 field.

In the device ID field 54, a device ID for identifying a device existing in the network is recorded. Therefore, the device ID can be recorded in a size (eg 1 byte) much smaller than the size of the hardware address (eg 8 bytes), thereby reducing overhead when communication between devices is made.

In the ATP field 55, the final timeout time determined by the network coordinator 200a is recorded. These times may be different if the network coordinator 200a cannot support the time requested in the ATP field 45 of FIG.

Code field 56 displays a value indicating approval or rejection of the join request. For example, 0 represents approval and 1 to 8 represent each reason for rejection. Reasons for rejection include reaching the maximum number of devices that can be coupled to the network coordinator, lack of assignable time slots, and poor channel conditions.

When the device 1 200a receives the join request by the join response frame 50, the device 1 200a becomes a member of the network. Then, if the device 1 200a wants to transmit uncompressed AV data to the device 2 200b, the network coordinator 100 should request a data slot for transmitting the uncompressed AV data (3 in FIG. 3). ).

The data slot request may be made through the data slot request frame 60 as shown in FIG. 6. The payload 20 of the data slot request frame 60 includes a control type field 61, a length field 62, and at least one request block field 63, 64, 65. The control type field 61 or the length field 62 is the same as the other control frames.

One request block field 64 identifies a target number field 64a representing the number of receiving devices, a target ID list field 64b enumerating the device IDs of the receiving devices, and a version of the data slot request frame 60. Stream request ID field 64c, stream index field 64d for identifying data to be transmitted, minimum time unit (TU) field 64e indicating the size of the minimum data slot to be requested, and data desired by the device And a desired TU field 64f indicating the size of the slot.

When the device 1 200a transmits such a data slot request frame 60 to the network coordinator 100 through competition with other devices 200b and 200c during the contention period of the super frame (③), the network The coordinator 100 transmits the data slot response frame 70 as shown in FIG. 7 to the device 1 200a (④).

The payload 20 of the data slot response frame 70 includes a control type field 71, a length field 72, a stream request ID field 73, a stream index field 74, and a number of available TUs field 75. ), And code field 76.

The fields 71, 72, 73, 74 are recorded in the same manner as in the data slot request frame 60. In addition, the number of available TUs field 75 records the number of TUs for one data slot, which is finally allocated by the network coordinator 100. Finally, code field 76 is marked with a value indicating approval or rejection of the data slot request.

After transmitting the response frame 70 to device 1 200a, network coordinator 100 assigns a superframe including data slots allocated to devices 200a, 200b, 200c to the beacon signal during the next beacon period. Carry on and broadcast (⑤).

When the device 1 200a is allocated a data slot from the network coordinator 100 by the broadcast superframe, the uncompressed AV data may be transmitted to a predetermined receiving device 200b during the allocated data slot (6). ). In response to the transmission of the uncompressed AV data, the device 2 200b may transmit an ACK frame to the device 1 200a (⑦). However, even if there is a slight error due to the nature of the uncompressed AV data, a large problem does not occur in the reproduced video. Therefore, a No ACK policy without using ACK may be used. Even if the ACK frame is transmitted, the ACK frame may not be transmitted through the data slot according to the present invention. In order to use the data slot for smooth transmission of uncompressed AV data, the ACK may be transmitted through contention during the contention period like other control frames.

8 to 13 illustrate the structures of the superframes 80, 90, 100, 110, 120, and 130 according to various embodiments of the present disclosure. The superframe according to the present invention is largely divided into a beacon transmission section, a competition section, and a non-competition section.

In the embodiments of the present invention, the contention section is distinguished from the conventional IEEE 802.15.3 in that the contention section is arranged separately from the section for the control frame related to a specific function of high importance. In other words, the conventional competition section is a section in which frames are acquired through competition regardless of time division, but in the present invention, the competition section itself is time-divided according to a specific function.

First, FIG. 8 is a diagram showing the structure of a superframe 80 according to the first embodiment of the present invention.

The contention section 82 is divided into a data slot reservation section 85 for requesting and responding to data slots, and a control & asynchronous data section 84 for use in transmitting and receiving control frames and asynchronous data frames irrelevant to the data slot reservation. Lose. The data slot request and response is an essential process for reserving a data slot for transmitting uncompressed AV data, so it is separated from other control frames or sections for asynchronous data frames. However, even if there is a separate section 85 as described above, slot reservation is not necessarily made only in this section 85, and slot reservation may be made through competition with other control frames in the control & asynchronous data section 84. have.

The non-competition section 83 consists of a plurality of data slots 86 and 87, each of which is used to transmit uncompressed AV data.

9 is a diagram showing the structure of the superframe 90 according to the second embodiment of the present invention.

Compared to FIG. 8, in addition to the control & asynchronous data section 94 and the data slot reservation section 96, the initial joining section 95 is disposed separately in the contention section 92. The initial joining section 95 is a section for transmitting and receiving a device joining request and response, which may be considered next important after data slot reservation. Accordingly, the device combining request frame or the device request response frame may be exclusively performed in the initial combining period 95.

FIG. 10 is a diagram illustrating a structure of a superframe 100 according to a third embodiment of the present invention.

9, it can be seen that the control section 104 and the asynchronous data section 107 are separated separately. The control interval 104 is a contention interval for control data transmission that is not related to initial combining and data slot reservation, and the asynchronous data interval 107 stores asynchronous data other than isochronous uncompressed AV data (eg, compressed AV data). It is a section to transmit.

FIG. 11 is a diagram illustrating a structure of a superframe 110 according to a fourth embodiment of the present invention. In the fourth embodiment, a plurality of control sections 114a and 114b 114c are distributed among the data slots 115, 116, and 117 in the superframe 110. Since the control periods 114a, 114b 114c are competition periods and the data slots 115, 116, 117 are non-competition periods, the control periods 114a, 114b 114c may be considered to be distributed in a competitive period and a non-competition period. Through such a distributed arrangement, the size of the buffer required for the device to perform uncompressed AV data transmission is reduced.

12 is a diagram illustrating the structure of a superframe 120 according to a fifth embodiment of the present invention.

Compared to FIG. 11, there is a difference in that the first competition section 122a is divided into a control section 124a and a data slot reservation section 125. As described above, the data slot reservation process is a prerequisite for transmitting uncompressed AV data and thus is separated into separate sections because of its high importance.

FIG. 13 is a diagram illustrating a structure of a superframe 130 according to a sixth embodiment of the present invention.

Compared to FIG. 8, the data slot reservation section 135 is disposed in the non-competition section 133 instead of the competition section 132. In the first embodiment of FIG. 8, since the data slot reservation interval 85 was in the contention period 82, there may be a device that does not even have an opportunity to transmit the data slot request frame according to the contention.

In the sixth embodiment, when the network coordinator 100 who knows the number of devices currently connected to the network broadcasts a superframe, the network coordinator 100 uses a method of notifying the data slot reservation interval corresponding to the number of devices. For example, when there are n coupled devices in a network, the data slot reservation interval 135 is time-divided into n to arrange time intervals 135a, 135b, and 135c for each device to reserve a data slot. . This ensures the opportunity for all devices to send a data slot request frame for data slot reservation.

14 is a block diagram showing the configuration of the network coordinator 100 according to an embodiment of the present invention.

The network coordinator 100 may control the CPU 110, the memory 120, the MAC unit 140, the PHY unit 150, the superframe generator 141, the control frame generator 142, and the antenna 153. It can be configured to include.

The CPU 110 controls other components connected to the bus 130 and is responsible for processing at the upper layer of the MAC layer. Accordingly, the CPU 110 processes the received data (received MSDU; MAC Service Data Unit) provided from the MAC unit 140 or generates and provides the transmitted data (transmitted MSDU) to the MAC unit 140.

The memory 120 stores the processed received data or temporarily stores the generated transmission data. The memory may be a nonvolatile memory device such as a ROM, a PROM, an EPROM, an EEPROM, a flash memory, or a volatile memory device such as a RAM, a hard disk, an optical disk, and the like. The same storage medium, or any other form known in the art.

The MAC unit 140 generates a MAC Protocol Data Unit (MPDU) by adding a MAC header to the MSDU, that is, the multimedia data to be transmitted from the CPU 110, and transmits it through the PHY unit 150, and transmits the PHY unit 150 to the MSDU. Remove the MAC header from the MPDU received through.

As such, the MPDU transmitted by the MAC unit 140 includes a superframe transmitted during the beacon period, and the MPDU received by the MAC unit 140 includes a combined request frame, a data slot request frame, and various other control frames. .

The superframe generator 141 generates one of the superframes shown in FIGS. 8 to 13 and provides it to the MAC unit, and the control frame generator 142 is a combination request frame, a data slot request frame, and various other controls. Create a frame and provide it to the MAC unit.

The PHY unit 150 generates a PPDU by adding a signal field and a preamble to the MPDU provided from the MAC unit 140, converts the generated PPDU, that is, a data frame into a radio signal, and transmits the converted signal through the antenna 153. PHY unit 150 generates a baseband processor (151) for processing the baseband signal (RF) for generating the actual radio signal from the processed baseband signal and transmits to the air through the antenna 153 (radio frequency) may be subdivided into units 152.

Specifically, the baseband processor 151 performs frame formatting, channel coding, and the like, and the RF unit 152 performs operations such as analog wave amplification, analog / digital signal conversion, and modulation. do.

15 is a block diagram illustrating a configuration of a wireless device 200 according to an embodiment of the present invention. The basic functions of the MAC unit 240, the memory 220, and the PHY unit 250 of the configuration of the wireless device 200 are the same as those of the network coordinator 100.

The timer 241 is used to check the start time and end time of the contention period or the contention period included in the superframe. The control frame generator 242 generates various control frames, such as a combined request frame and a data slot request frame, and provides them to the MAC unit 240.

On the other hand, the uncompressed AV data generation unit 243 records and generates the AV data in an uncompressed form. For example, the uncompressed AV data generator 243 records video data composed of RGB component values of the video data.

The MAC unit 240 generates an MPDU by adding a MAC header to the provided uncompressed AV data or control frame, and transmits the MPDU through the PHY unit 250 when the corresponding time of the super frame is reached.

To date, each of the components of FIGS. 2 to 6 is a software, such as a task, a class, a subroutine, a process, an object, an execution thread, a program, or a field-programmable gate array (FPGA) that is performed in a predetermined area on a memory. Or may be implemented in hardware, such as an application-specific integrated circuit (ASIC), or a combination of the software and hardware. The components may be included in a computer readable storage medium or a part of the components may be distributed and distributed among a plurality of computers.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

1 is a diagram comparing frequency bands between the IEEE 802.11 family of standards and mmWave.

2 shows a time division scheme in accordance with IEEE 802.15.3.

3 shows a schematic environment to which the present invention is applied;

4 is a diagram illustrating a configuration of a join request frame according to an embodiment of the present invention.

5 is a diagram illustrating a configuration of a combined response frame according to an embodiment of the present invention.

6 illustrates a configuration of a data slot request frame according to an embodiment of the present invention.

7 is a diagram illustrating a configuration of a data slot response frame according to an embodiment of the present invention.

8 is a diagram showing the structure of a superframe according to the first embodiment of the present invention;

9 illustrates the structure of a superframe according to a second embodiment of the present invention.

10 is a diagram showing the structure of a superframe according to a third embodiment of the present invention;

11 illustrates the structure of a superframe according to a fourth embodiment of the present invention.

12 illustrates the structure of a superframe according to a fifth embodiment of the present invention.

FIG. 13 is a diagram showing the structure of a superframe according to a sixth embodiment of the present invention; FIG.

14 is a diagram showing the configuration of a network coordinator according to an embodiment of the present invention.

15 is a diagram illustrating a configuration of a wireless device according to an embodiment of the present invention.

(Symbol description of main part of drawing)

100: network coordinator 110, 210: CPU

120, 220: memory 130, 230: bus

140, 240: MAC unit 141: Super frame generation unit

142, 242: control frame generation unit 150: PHY unit

151, 251: baseband processor 152, 252: RF unit

153, 263: antenna 200: wireless device

241: timer 243: uncompressed AV data generator

Claims (4)

A superframe receiving unit for receiving a first superframe from a network coordinator during the first beacon period; A request frame transmitting unit for transmitting a frame requesting a data slot to the network coordinator to the network coordinator within a data slot reservation period included in the first superframe; And When the superframe receiving unit receives a second superframe including a data slot allocated from the network coordinator during a second beacon period, data for transmitting uncompressed AV data to another wireless device during a period corresponding to the data slot. A transmission unit, The communication with the network coordinator is via a millimeter wave channel, the first and second superframes are uncompressed AV data transmission apparatus in which a plurality of control intervals are distributed among a plurality of data slots. The apparatus of claim 1, wherein the data slot reservation section is a contention section and is disposed adjacent to one of the divided control sections. The uncompressed AV data transmission device of claim 1, wherein the data slot reservation interval is a non-competition interval and is disposed adjacent to any one of the plurality of data slots. The method of claim 3, wherein the data slot reservation interval is The uncompressed AV data transmission device comprising time-division sections for each of the at least one wireless device.

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