KR101821350B1 - Video streaming system, wireless communication apparatus in wireless lan environment and method thereof - Google Patents

Abstract

In the present invention, in video transmission in a wireless LAN-based multi-cell multicast environment, a wireless communication device such as each access point that transmits a multicast video packet to a terminal device transmits wireless channel information with the terminal device The transmission efficiency of the multicast video packet is increased by independently setting the FEC encoding ratio for transmission of the multicast video packet. That is, terminal devices receiving a video multicast service feed back wireless channel information to a wireless communication device such as an access point having an FEC encoding ratio adjustment function, and use an independent FEC encoding ratio for each access point using wireless channel information So that unnecessary waste of radio resources due to a low FEC encoding ratio can be prevented. Also, when the access points operating in the same channel have transmission areas overlapping each other, transmission timings of video packets between access points are set differently so that a video packet collision does not occur in a terminal device located in an overlapping transmission area.

Description

TECHNICAL FIELD [0001] The present invention relates to a video transmission system, a wireless communication apparatus, and a video communication method in a wireless LAN environment.

The present invention relates to a video transmission method in a wireless LAN environment and more particularly to a video transmission method in a wireless LAN based multi-cell multicast environment. Each wireless communication device, such as an access point, transmits a forward error correction (FEC) encoding ratio for transmission of a multicast video packet based on wireless channel information with the terminal device rate is set independently to increase the transmission efficiency of the multicast video packet and the transmission time of the video packet is set differently for the overlapping transmission area between the wireless communication devices to prevent collision of the video packet To a video transmission system, a wireless communication apparatus, and a method in a LAN environment.

In recent years, the demand for multimedia internet service (mulit-media internet service) has increased so much that multimedia services such as video streaming are being expanded even in a wireless LAN environment. Particularly, a multicast scheme for transmitting one video content to several subscribers at the same time can be very effective in terms of transmission efficiency. Such a video streaming service is a multi-cell environment having a wide coverage, .

Meanwhile, 802.11 wireless LAN basically supports ARQ (automatic repeat request) in a unicast transmission scheme. That is, the receiving terminal informs the transmitting terminal that a data frame has been successfully received through transmission of an ACK (acknowledgment) frame defined in advance, and does not transmit an ACK frame in case of transmission failure, thereby retransmitting the transmitting terminal .

However, in the multicast transmission scheme, ACK frame transmission is not supported for a plurality of reception terminals. As a result, the transmitting terminal can not confirm whether or not the data has been correctly transmitted, and therefore, retransmission is impossible. In a wireless communication environment, a loss due to a wireless channel and a loss due to interference with other signals may occur. Therefore, in a multicast transmission method in which an ACK frame transmission is not supported as described above, such loss can not be properly restored.

As a conventional method for solving such a problem, for example, a forward error correction (FEC) scheme in an application layer can be used. That is, the application layer generates additional redundant packets using a predefined FEC scheme, and restores the original data even if a partial loss occurs during transmission. In the case of using the FEC scheme, the amount of data to be transmitted increases due to the coding technique, which may result in overhead in terms of performance. However, the advantage of recovering failed data on its own without re- . That is, it is very suitable for a multicast transmission method in which retransmission is impossible.

However, conventional schemes that simply use a fixed FEC encoding ratio without considering the transmission loss situation may be inefficient or meaningless. The FEC encoding ratio is determined by the amount of encoded data versus the original data. The lower the value, the stronger the transmission loss, but there is a disadvantage that more data must be sent. For example, in situations where there is little transmission loss, using FEC encoding itself may be unnecessary overhead and may require a lower coding rate in environments with high transmission losses. There is a limit to simply using a fixed coding rate without considering these various situations. There is a method of dynamically changing the FEC encoding ratio based on the channel information sent from the receiving side in order to solve the problem in the conventional FEC method using the fixed coding rate.

Korean Registered Patent No. 10-0263139 On August 1, 2000, when data having the current FEC rating is received, information on the channel is obtained, and the obtained channel information is compared with a predetermined threshold level A technique for selecting an FEC variable corresponding to a channel is better or worse than a threshold level. IEEE 802.11n WLAN, "Video Packet Adaptation Layer for Reliable Video Multicast over IEEE 802.11n WLAN," (Computer Communications (ComCom), Vol. 33, No. 18, pp. 2271-2281, Dec. 2010) In this paper, we propose a method of using application layer FEC based on Raptor code for efficient video multicast in LAN environment. Based on channel information sent by users, Raptor coding rate and PHY layer transmission rate A technique capable of dynamically changing a video stream to support reliable video streaming and simultaneously maximizing radio resource efficiency is disclosed.

However, the conventional dynamic FEC encoding ratio changing method is not suitable for a WLAN-based multi-cell multicast environment. This is because the FEC encoding ratio required in each cell may be different from each other, but in the FEC encoding process, all of the cells having the worst channel based on the feedback information received from each cell are forced to use the same FEC encoding ratio . In addition, in order to support independent FEC encoding ratios for each cell, a serious overhead may be incurred to add a separate FEC encoding function to each wireless communication device, for example, an access point.

1 illustrates the concept of a general application layer FEC-based video multicast from a video server 100 to a terminal device 108, 110, 112, 114 in a conventional multi-cell multicast environment. Conventionally, since all of the access points 102, 104, and 106 have the same FEC encoding ratio, the first terminal device 108 and the fourth terminal device 114 have many parity packets compared to a good radio channel situation It can be confirmed that unnecessary overhead is generated.

In addition, as shown in FIG. 2, in each of the access points 102 and 104, for the terminal device 108 located in the area 200 where the wireless transmission areas of the two access points 102 and 104 overlap, There is a problem that data collision occurs when a video packet is transmitted without taking the position of the video packet 108 into consideration. That is, the access points 102 and 104 transmit multicast and broadcast packets to beacon frames, which are transmitted in a specific cycle of delivery traffic indicator message (DTIM) beacon, In the terminal device 108 located in the area 200 where the wireless transmission area of the access point overlaps to transmit the cast video packet, a collision of video packets occurs as shown in FIG.

Accordingly, it is an object of the present invention to provide a wireless communication device, such as an access point, for transmitting a multicast video packet to a terminal device in a multi-cell multicast environment based on a WLAN, The transmission efficiency of the multicast video packet is increased by independently setting the FEC encoding ratio for transmission of the packet and the transmission time of the video packet is set differently for the overlapping transmission areas between the wireless communication devices, The present invention provides a video transmission system, a wireless communication apparatus, and a method in a wireless LAN environment.

The present invention relates to a video transmission system comprising: a video server for transmitting a video packet; a FEC for receiving the video packet transmitted in a multicast from the video server and encoding the video packet according to a radio channel condition in a wireless transmission region forward error correction (FEC) encoding rate of the video packet and reconfiguring the video packet according to the adjusted FEC encoding ratio, and wirelessly transmitting the video packet; and a terminal device for receiving the multicast video packet transmitted from the wireless communication device .

In addition, the wireless communication apparatus may further include a method of calculating the number of packets that need to be deleted according to the FEC encoding ratio for the video packets received from the video server, and deleting the calculated number of packets from the video packets at random And reconstructing the video packet.

In addition, the wireless communication apparatus sets the transmission timing of the video packet different from that of the other wireless communication apparatus when adjacent wireless communication apparatuses in which the wireless transmission regions overlap each other exist.

According to another aspect of the present invention, there is provided a wireless communication apparatus comprising: a relay unit for receiving a video packet received in a multicast manner and transmitting the received video packet to a terminal device in a wireless transmission region; And an adjusting unit adjusting the FEC encoding ratio to encode the video packet, reconfiguring the video packet according to the adjusted FEC encoding ratio, and wirelessly transmitting the video packet to the terminal apparatus.

Also, the controller adjusts the FEC encoding ratio to correspond to the changed radio channel condition as the radio channel condition is changed.

Also, the control unit may be configured to calculate the number of packets required to be deleted according to the FEC encoding ratio for the video packet, and reconstruct the video packet in such a manner that the calculated number of packets are arbitrarily deleted from the video packet .

The controller may set the transmission timing of the video packet different from that of the other wireless communication apparatus when adjacent wireless communication apparatuses in which the wireless transmission regions overlap each other are present.

Further, the controller adjusts a transmission period of the video packet by changing a transmission period of the DTIM beacon.

The controller may receive information on a radio channel condition in the radio transmission region from the terminal apparatus.

According to another aspect of the present invention, there is provided a video transmission method comprising: receiving a video packet transmitted from a video network server on a communication network in a wireless communication apparatus in a multicast manner; and transmitting the video packet to a terminal apparatus in a wireless transmission region in the wireless communication apparatus Checking a wireless channel condition for the video packet; setting a new FEC encoding ratio for the video packet according to the wireless channel condition; and reconstructing the video packet according to the FEC encoding ratio.

In addition, the FEC encoding ratio is adjusted to correspond to the changed radio channel status as the radio channel status is changed.

In addition, the step of reconstructing the video packet may include calculating the number of packets requiring deletion according to the FEC encoding ratio for the video packet received from the video server, And reconstructing the video packet by arbitrarily deleting the packet from the packet.

Further, the wireless communication apparatus is an access point.

The present invention also provides a video transmission method comprising the steps of: receiving a video packet transmitted from a video server on a communication network in a wireless communication device in a multicast manner; and transmitting the video packet transmitted from the wireless communication device to another wireless communication device Determining whether a transmission time of the video packet is different from that of the other wireless communication apparatus when the other wireless communication apparatus exists; and transmitting the video packet to the terminal apparatus .

In addition, the transmission time of the video packet is differently set by changing the transmission period of the DTIM beacon.

In a video transmission in a wireless LAN-based multi-cell multicast environment, a wireless communication apparatus such as each access point, which transmits a multicast video packet to a terminal apparatus, The transmission efficiency of the multicast video packet can be increased by independently setting the FEC encoding ratio for transmission of the multicast video packet. That is, terminal devices receiving a video multicast service feed back wireless channel information to a wireless communication device such as an access point having an FEC encoding ratio adjustment function, and use an independent FEC encoding ratio for each access point using wireless channel information So that unnecessary waste of radio resources due to a low FEC encoding ratio can be prevented.

Also, when the access points operating in the same channel have transmission areas overlapping each other, transmission timings of video packets between access points are set differently so that collision of video packets does not occur in a terminal device located in an overlapping transmission area, There is an advantage that the transmission efficiency can be increased.

1 is a conceptual diagram of a conventional multicast video transmission system,
Figure 2 is an illustration of a wireless transmission area that overlaps conventional access points,
FIG. 3 is a diagram illustrating an example of a collision of video packets between access points using the same channel,
4 is a conceptual diagram of a multicast video transmission system according to an embodiment of the present invention,
5 is a detailed block diagram of an access point according to an embodiment of the present invention;
6 is a diagram illustrating an example of a video transmission timing adjustment for preventing collision of video packets between access points according to an embodiment of the present invention;
7 is a flow chart of signal processing for multicast video transmission in accordance with an embodiment of the present invention.

Hereinafter, the operation principle of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The following terms are defined in consideration of the functions of the present invention, and these may be changed according to the intention of the user, the operator, or the like. Therefore, the definition should be based on the contents throughout this specification.

FIG. 4 illustrates a network configuration of a wireless LAN-based video transmission system according to an exemplary embodiment of the present invention, and includes a video server, a wireless communication device, a terminal device, and the like.

Hereinafter, the operation of each component of the video transmission system of the present invention will be described in detail with reference to FIG. In particular, in the present invention, access points 402, 404, and 406, which are one of the wireless communication devices, will be described as an example of a wireless communication device.

First, the video server 400 stores various video contents for a multimedia internet service and provides the video contents to the terminal devices 408, 410, 412, and 414 through a communication network.

In a wireless communication environment, a transmission loss due to a wireless channel may occur. Also, 802.11 wireless LAN supports collision avoidance based channel access method, but collision can occur due to overlapping probabilities of wireless transmission areas. If such a transmission collision occurs, a loss also occurs. However, in a multicast environment, it is impossible to retransmit and this loss can not be restored. In order to solve this problem, the video server 400 divides the video data into packet units before delivering the video data to the access points 402, 404, and 406, which are wireless communication devices, ) ≪ / RTI > coding scheme. The encoded video data is transmitted to the terminal devices 408, 410, 412, and 414 through the respective access points 402, 404, and 406 and transmitted to the terminal devices 408, 410, and 412 , 414 reconstruct the video data that was originally intended to be transmitted through decoding. In this case, it is assumed that the minimum FEC encoding ratio exists for the above operation.

The access points 402, 404, and 406 are repeaters that connect the wired LAN and the wireless LAN. As shown in FIG. 5 illustrating the detailed block configuration of the access point 404, the access points 402, 404, and 406 include a relay unit 500, And a control unit 506. The video server 400 receives the multicast video packet transmitted from the video server 400 to the plurality of terminal apparatuses 410 and 412 and transmits the multicast video packet To each terminal device (410, 412) located in the transmission area.

The relay unit 500 connects each of the terminal devices 410 and 412 present in the access point 404 to the communication network using Wi-Fi, Bluetooth or a related wireless communication standard in a computer network. The authentication unit 502 performs authentication for the terminal devices 410 and 412 that are located in the wireless transmission region and want to access the communication network. The control unit 504 controls the overall operation of the access point 404 according to a predetermined operation program and drives the relay unit 500 and the authentication unit 502.

The controller 506 receives the channel state information in the wireless transmission region of the access point 404 from the terminal devices 410 and 412 in the wireless LAN based multi-cell multicast environment, Sets the FEC encoding rate for transmission of video packets. In addition, it is checked whether or not the wireless transmission areas overlap with the adjacent access points 402 and 406, so that the transmission time of the video packet is differently set for the transmission area overlapping between the access points, . In the above description, the access point 404 of one of the access points 402, 404, and 406 has been described as an example, but the same can be applied to the remaining access points 402 and 406.

Hereinafter, the operation of the control unit 506 in the access point 404 will be described in more detail.

The controller 506 periodically reports radio channel information on the radio channel status between the access point 404 and the terminal devices 410 and 412 from the respective terminal devices 410 and 412.

Then, the controller 506 selects a terminal apparatus having the worst radio channel condition at the access point 404 based on the received radio channel information, and transmits the selected access point 404 ) ≪ / RTI > encoding rate. This is to efficiently transmit multicast video packets reflecting the radio channel conditions.

At this point, the adjuster 506 may be mounted on each access point 402, 404, 406 and may be configured to receive the access point 402, 404, 406 in a manner that randomly deletes some of the data generated by the lowest FEC encoding rate , 404, 406). Basically, the video server 400 having the video source selects the lowest FEC encoding ratio in the application layer, performs FEC encoding, and then delivers the encoded multicast video packet to each access point.

Each of the access points 402,404 and 406 receiving the encoded multicast video packet may then transmit the determined FEC encoding rate from the coordinator 506 in the access points 402,404 and 406, And multicast the remaining video packets to each of the terminal devices 408, 410, 412, and 414 in a wireless manner.

For example, if the amount of original multicast video data is a, the actual access point 402, 404, 406 obtained through the lowest FEC encoding ratio is b, and the amount of data received by the access point 402, 404, 406 , The access points 402, 404, and 406 transmit only the data of (a / c) among the data of the total b by radio and the remaining b- (a / c) So that the FEC encoding ratio c to be actually obtained is set. This is equivalent to the puncturing effect used to change the coding rate in the FEC encoding scheme.

As described above, since the packets deleted at the access points 402, 404, and 406 are applied to the terminal devices 408, 410, 412, and 414 in the same way as the transmission loss, The total loss is taken as the sum of the losses incurred in transmission, and the original data is restored by FEC decoding of the parts that are not lost. In this case, the access points 402, 404, 406 merely add the ability to delete some of the packets in accordance with the FEC encoding rate determined by the modifier 506 without any additional FEC encoding function, , 406) independent FEC encoding can be applied.

Next, when the access points 402, 404, and 406 operating on the same channel have overlapping wireless transmission areas, the transmission time of video packets between the access points 402, 404, and 406 are made different from each other, The timing of transmission of the video packets of each access point 402, 404, 406 may be adjusted to avoid collision between video packets.

That is, the control unit 506 of the access point 404 checks the location and transmission area of each access point 402, 404, and 406 to determine whether there is a wireless transmission area overlapping each other. At this time, it is assumed that the positions of the respective access points 402, 404, and 406 can be grasped through a database. Accordingly, the coordinator 506 may be configured to determine the distance between the access points 402,404, 406 and the wireless transmission zone 402,404, 406 between the access points 402,404, 406, Can be confirmed. It is also possible to grasp the relationship of the access points 402, 404, and 406 where the wireless transmission regions overlap through measurement of the actual terminal devices 408, 410, 412, and 414.

In order to adjust the transmission timing of the video packet, the controller 506 sets the maximum video transmission time per unit time in consideration of the amount of video packets per unit time, the physical layer transmission rate, the wireless LAN MAC overhead, the minimum FEC encoding ratio, .

For example, video is transmitted in units of Group of Pictures (GoP), which is a video encoding unit. Therefore, when the unit time is referred to as GoP time, the maximum video transmission time per GoP time is calculated considering the lowest FEC encoding ratio . It calculates how many video transmissions are possible within one GoP time and expresses it as the maximum number of nonoverlapping. That is, if the GoP time is 0.5 second and the video to be transmitted during the GoP time requires 0.1 second when using the lowest FEC encoding rate, the maximum non-overlapping number is 5.

In the IEEE 802.11 standard, when there is a terminal device using power saving, multicast and broadcast packets are queued without being directly transmitted, and a beacon frame transmitted at a specific period called a delivery traffic indicator message (beacon) . The control unit 506 controls the access points 402, 404, and 406 having overlapping transmission areas operating on the same channel to differentiate the timing of sending the DTIM beacon so as to avoid collision between video packets .

FIG. 6 illustrates an example of a situation in which collision is avoided by changing the transmission timing of video packets for each access point 402, 404, and 406. In the case of access points adjacent to each other, The time of transmission of the DTIM beacon may be different by the video transmission time so that collision between the video packets can be prevented.

That is, the controller 506 sets the DTIM interval, which is the period in which the DTIM beacon of each access point is transmitted, to be the same as the GoP time so that the multicast frames are transmitted immediately after each DTIM beacon.

For example, if the GoP time is 0.5 second, the DTIM cycle is also 0.5 second. If the video to be transmitted during the GoP time is 0.1 second, the DTIM beacon transmission timing of the access points having overlapping transmission areas is shifted by 0.1 second Can be controlled. At this time, when the access points for the video multicast service are installed, the communication service provider can arrange the maximum number of neighbor access points by adjusting the number of the previously calculated video to be less than or equal to the maximum number of overlaps with each other. Accordingly, when transmission areas of access points overlap each other, video transmission timing can be implemented differently.

7 illustrates a signal processing flow for multicast video transmission in a video transmission system according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 4, 5, 6, and 7. FIG. In the description of the present invention, the operation in the access point 404 will be described as an example for convenience of explanation, but the same applies to other access points 402 and 406 as well.

First, a communication service provider can arrange access points considering the number of maximum neighbor access points when access points 402, 404, and 406 for a video multicast service are installed, and a wireless LAN-based video multicast environment The video server 400 transmits the multicast video packet to the terminal devices 408, 410, 412, and 414 using the FEC encoding technique of the application layer.

When the above-described video multicast environment is established, the access point 404 determines a DTIM beacon transmission time for transmitting the multicast video packet received from the video server 400 to the terminal device 410 (S700). At this time, the access point 404 verifies whether the wireless transmission areas overlap with a plurality of access points 402 and 406 existing at adjacent locations using information stored in a database or the like, and determines whether there is an access point It is possible to prevent collision of video packets by setting different transmission timings of the DTIM beacon through communication with the corresponding access point.

Then, the access point 404 newly sets an independent FEC encoding ratio for each access point by using the wireless channel information in the wireless transmission region, and transmits the video packet more efficiently by transmitting the video packet.

That is, the terminal device 410 periodically transmits radio channel information for radio channel conditions in the radio transmission region of the access point 404 (S702) (S704) and newly sets an independent FEC encoding ratio of the access point 404 different from the FEC encoding rate of the video packet transmitted from the video server 400 (S706) .

Thereafter, when a multicast video packet is transmitted from the video server 400 to the access point 404 in step S708, the access point 404 receives the multicast video packet from the video server 400 in step S710, The point 404 reconstructs the video packet with the independently set FEC encoding ratio (S712).

At this time, in the reconstruction of the video packet as described above, the access point 404 transmits a predetermined number of packets calculated according to the FEC encoding ratio to the multicast video packets < RTI ID = 0.0 > And wirelessly transmits the reconfigured video packet to each of the terminal devices 410 by multicasting.

For example, if the amount of original multicast video data is a, the amount of data received by the actual access point 404 obtained through the lowest FEC encoding ratio is b, the FEC encoding ratio suitable for the access point 404 is c The access point 404 transmits only the data of (a / c) in the data of the total b by radio, and the other (b- (a / c)) is arbitrarily deleted to obtain the FEC encoding ratio c It will fit.

Then, the access point 404 transmits the reconfigured video packet to the terminal device 410 located in the access point wireless transmission area (S714).

Accordingly, the terminal device 410 restores and reproduces the video packet through the FEC decoding, and transmits wireless channel information for the wireless transmission region of the access point 404 (S716).

Then, the access point 404 receives the radio channel information for the radio transmission region of the access point 404 from the terminal device 410 in feedback (S718), analyzes the radio channel information, and adjusts the FEC encoding ratio The FEC encoding ratio is adjusted again according to the wireless channel information (S720), and the video packet is reconstructed with the adjusted FEC encoding ratio.

As described above, in the present invention, in a video transmission in a wireless LAN-based multi-cell multicast environment, a wireless communication apparatus such as each access point, which transmits a multicast video packet to a terminal apparatus, The transmission efficiency of the multicast video packet is increased by independently setting the FEC encoding ratio for transmission of the multicast video packet based on the wireless channel information.

That is, terminal devices receiving a video multicast service feed back wireless channel information to a wireless communication device such as an access point having an FEC encoding ratio adjustment function, and use an independent FEC encoding ratio for each access point using wireless channel information So that unnecessary waste of radio resources due to a low FEC encoding ratio can be prevented.

Also, when the access points operating in the same channel have transmission areas overlapping each other, transmission timings of video packets between access points are set differently so that a video packet collision does not occur in a terminal device located in an overlapping transmission area.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. That is, in the embodiment of the present invention, the access point is provided with the function of setting the FEC encoding ratio in independently setting the FEC encoding ratio for each access point. However, when the video server transmits the FEC encoding ratio And one of the multiple access points may set the FEC encoding rate for each access point. Accordingly, the scope of the invention should not be limited by the described embodiments but should be defined by the appended claims.

In the present invention, in video transmission in a wireless LAN-based multi-cell multicast environment, a wireless communication device such as each access point that transmits a multicast video packet to a terminal device transmits wireless channel information with the terminal device The present invention can be applied to a wireless communication apparatus such as a wireless communication network and an access point by independently setting an FEC encoding ratio for transmission of a multicast video packet to increase the transmission efficiency of the multicast video packet.

400: video server 402, 404, 406: access point
408, 410, 412, 414:

Claims (15)

delete delete delete A wireless communication apparatus comprising:
A relay unit for multicasting a video packet encoded with a first forward error correction (FEC) encoding ratio from a video server;
Determining a second FEC encoding ratio based on a wireless channel condition with a terminal device within a wireless transmission region of the wireless communication device and assuming that the received video packet is encoded with the second FEC encoding rate And an adjusting unit for calculating at least one arbitrary packet from the video packet so that the number of packets of the received video packet is the calculated number of packets,
The relay unit includes:
The at least one arbitrary packet is transmitted to the terminal device
Wireless communication device. 5. The method of claim 4,
The control unit includes:
And adjusts the FEC encoding ratio to correspond to the changed radio channel condition as the radio channel condition is changed. delete 5. The method of claim 4,
The control unit includes:
And sets the transmission timing of the video packet different from that of the other wireless communication apparatus when adjacent wireless communication apparatuses in which the wireless transmission regions overlap each other exist. 8. The method of claim 7,
The control unit includes:
Wherein the transmission timing of the video packet is adjusted by changing a transmission period of the DTIM beacon. 5. The method of claim 4,
The control unit includes:
And receives information on a radio channel condition in the radio transmission region from the terminal apparatus. A video transmission method performed in a wireless communication device,
Multicast a video packet encoded with a first FEC encoding rate from a video server,
Checking a radio channel condition with a terminal device in a radio transmission region of the radio communication device;
Determining a second FEC encoding ratio according to the radio channel condition,
Calculating a number of packets when assuming that the received video packet is encoded with the second FEC encoding rate;
Deleting at least one arbitrary packet from the video packet such that the number of packets of the received video packet is the calculated number of packets;
And transmitting the deleted video packet to the terminal device
Video transmission method. 11. The method of claim 10,
The FEC encoding ratio may be,
And adjusting the radio channel status according to the changed radio channel status as the radio channel status is changed. delete delete 11. The method of claim 10,
Checking whether there is another wireless communication device in a neighboring area where a wireless transmission area overlaps in the wireless communication device;
Setting a transmission time of the video packet different from that of the other wireless communication apparatus when the other wireless communication apparatus exists;
And transmitting the video packet to the terminal device at a transmission time different from the predetermined transmission time
Video transmission method. 15. The method of claim 14,
Wherein the transmission time of the video packet
Is set differently by changing the transmission period of the DTIM beacon
Video transmission method.

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