KR101397908B1 - Video wireless relay system and method thereof - Google Patents

Abstract

The present invention relates to a wireless video relay system and a method thereof. The purpose of the present invention is to provide a wireless video relay system and method, and a computer-readable recording medium in which a program for realizing the method is recorded for relaying a video through a plurality of channels on a wireless relay network comprising FDM and TDM and extending the wireless transmission distance with a wireless relay method to transmit a video to a remote place. For this, the video wireless relay method comprises the following steps: a) setting a link by interchanging node information through a control channel between a plurality of nodes and an access point (AP); b) allowing an access point to allocate time slot and a service channel (SCH) to the nodes; c) in which the nodes convert the channel from the control channel into the SCH; d) performing DHCP process by the nodes and AP; e) and transmitting and relaying video data to the AP from the nodes. In step a), AP can set the nodes and a plurality of communication links in parallel.

Description

Technical Field [0001] The present invention relates to a video wireless relay system and method thereof,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image wireless relay system and method for relaying images wirelessly, and a computer readable recording medium storing a program for realizing the method, and more particularly, A video wireless relay system for relaying an image through a plurality of channels on a wireless relay network in which a wireless transmission distance is extended in a wireless relay system and a combination of FDM (Frequency Division Multiplexing) and TDM (Time Division Multiplexing) And a computer-readable recording medium storing a program for realizing the method and the method.

In the following embodiments of the present invention, a system for relaying images photographed by a CCTV (Closed Circuit TV) camera through a plurality of wireless channels and a method thereof will be described as an example, but the present invention is not limited thereto .

The CCTV system can be classified into a wired transmission method and a wireless transmission method depending on the method of transmitting the photographed image. Since the amount of data is large, most of the images are transmitted through the wired communication method at the beginning, but recently, the wireless communication method has been changed to a convenient wireless communication method due to the development of wireless communication technology.

In the wireless transmission system, the point-to-point transmission between the control center and the camera has mainly been performed. In recent years, as the IEEE802.11 series wireless local area network (WLAN) standard has been commercialized, ) Based open protocol, and IP cameras are widely used accordingly. Wireless CCTV cameras for surveillance still depend on point-to-point transmission method, and remote transmission is realized by increasing output.

However, in a wireless network environment in which a plurality of cameras are required to install, it is impossible to communicate with a plurality of cameras through a single access point (AP) in a control center, resulting in a complicated implementation. For example, this corresponds to a "security surveillance camera system with a built-in binary CDMA modem (disclosed on Jul. 01, 2009) " disclosed in Korean Patent Publication No. 10-2009-0069491, And has a disadvantage that operation is restricted in a wireless network environment.

In recent years, a video transmission method of connecting a wireless LAN (WLAN) or a mesh type using an IP camera has been widely used. However, since the fluctuation due to the traffic of the communication network is significant, satisfactory quality of service (QoS) It is difficult to receive and use for security surveillance requiring reliability. For example, in the "CCTV management system using a wireless LAN with increased data transmission range " disclosed in Korean Patent Laid-Open No. 10-2010-0001347 (published on Jan. 6, 2010) And multiplexes the packets sequentially in the direction close to the CCTV camera at the farthest distance from the control center, and transmits the packets as one packet to the control center. However, since this method also relies on data packet communication, it is difficult to guarantee quality of service (QoS) as described above, and it is sensitive to delay due to limitations of packet communication, .

IEEE802 series wireless LAN (WLAN) technology is evolving with various standards. In the early days, the 2.4G Industrial Scientific Medical (ISM) band was used, but due to the common use with many industrial devices such as electronic ovens and Bluetooth, the frequency usage is very congested and it is currently being used in the 5.8G band. In the modulation and demodulation method, the DSS method is used at the beginning, but at present, high-speed communication is possible by providing high-speed communication using OFDM (Orthogonal Frequency Division Multiplexing) method. IEEE802.141 is known to support a transmission speed of 6 ~ 54Mbps with a 20M channel bandwidth in 5.8G frequency band, but the actual transmission speed is known to be about 25Mbps. IEEE802.11P is a standard that complements IEEE 802.141 to support safe operation of vehicles with fast mobility. The IEEE 802.11P standard has been established with the goal of shortening the time required for the connection by constructing 7 channels having 10 MHz bandwidth of the OFDM scheme so as to transmit urgent short messages as soon as possible. Therefore, there is a disadvantage that it is not suitable for a streaming service in which a large amount of data and high image quality are required, such as a CCTV camera image.

Therefore, the above-described conventional techniques are limited in operation in a wireless network environment in which a large number of cameras are installed due to a large complexity in implementation, or fluctuation due to traffic of a communication network is severe, so that a satisfactory quality of service (QoS) It is not suitable for streaming service which is difficult to use for security surveillance which is sensitive to delay and reliability is required, or which requires a large amount of data and high image quality such as CCTV camera image. To solve such a problem, It is one of the tasks.

Therefore, an embodiment of the present invention provides an image wireless relay system and method for relaying images over a plurality of channels in a wireless relay network in which a wireless transmission distance is extended to a wireless relay system, and a computer recording a program for realizing the method A recording medium which can be read is provided.

That is, in the embodiment of the present invention, in order to transmit an image to a remote place, a radio relay distance is extended and a plurality of channels on a wireless relay network, which is a mixture of FDM (Frequency Division Multiplexing) and TDM (Time Division Multiplexing) There is provided an image wireless relay system and method for relaying images, and a computer readable recording medium on which a program for realizing the method is recorded.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. It will also be readily apparent that the objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

A system according to an embodiment of the present invention is an image wireless relay system including an access point for dynamically allocating channel information to a plurality of nodes and receiving image data from the plurality of nodes through a plurality of wireless transmission paths AP); And a plurality of nodes for transmitting and relaying video data through the plurality of wireless transmission paths using channel information allocated from the access point, wherein the channel information is transmitted in a frequency division multiplexing (FDM) Wherein the plurality of channels are information for allocating a plurality of channels and a time slot by assigning a plurality of channels and time slots to the separated channel frequency in a TDM (Time Division Multiplexing) And the SCH transmits and receives control data and image data while switching channels, and the access point can communicate with the plurality of nodes through the plurality of communication links in parallel with the plurality of wireless transmission paths .

Another system according to an embodiment of the present invention is an image wireless relay system, in which channel information is dynamically allocated to a plurality of nodes, and image data is received from the plurality of nodes through a plurality of wireless transmission paths An access point (AP); And a control center for managing the surveillance region through the video data received through the access point, wherein the plurality of wireless transmission paths transmit and relay the video data in a wireless relaying manner, (TDM) scheme to allocate a plurality of channels and timeslots to the separated channel frequency by using a frequency division multiplexing (TDM) scheme, Wherein the access point relays and transmits the control data and the video data while switching channels between the CCH and the SCH in accordance with the channel information allocated from the access point and the access point is connected in parallel with the plurality of wireless transmission paths, Communication via a communication link.

Each of the nodes comprising: photographing means for photographing and encoding an image; And a wireless transmission controller for relaying and transmitting the control data and the video data using the channel information allocated from the access point (AP).

According to another aspect of the present invention, there is provided an image wireless relay system including a plurality of nodes for transmitting and relaying image data through a plurality of wireless transmission paths using channel information allocated from an access point, Each of the nodes comprising: photographing means for photographing and encoding an image; And a radio transmission controller for relaying and transmitting control data and video data using the channel information allocated from the access point (AP), wherein the channel information is divided into a channel frequency by a frequency division multiplexing (FDM) And allocates and allocates a plurality of channels and time slots in a TDM (Time Division Multiplexing) scheme to the separated channel frequency, and the plurality of nodes allocate a time slot between the CCH and the SCH in accordance with the channel information allocated from the access point And relaying and transmitting control data and image data while switching channels, and the access point is capable of communicating with the plurality of nodes through the plurality of communication links in parallel with the plurality of wireless transmission paths.

The video wireless relay system can adjust the time allocation ratio between the downlink and the uplink according to the number of relay hops and the number of the photographing means.

(N is a natural number) for transmitting image data taken by the node to the (N-1) -th node located at the longest distance from the access point and adjacent to the access point on the side of the access point, An (N-1) -th node for transmitting and relaying image data taken by the node itself and image data received from the N-th node to an (N-2) -th node adjacent to the access point, N-1) th node, and a first node for transmitting and relaying image data received from the second node and image data received from the second node to the access point, Path, respectively.

The plurality of channels may include one CCH (Control CHannel) and a plurality of SCHs (Service CHannel).

The CCH includes a C-CCH (Common Control CHannel), and the plurality of SCHs may include a plurality of C-SCH (Control Service CHannel) and D-SCH (Data Service CHannel).

The plurality of C-SCHs and D-SCHs can be divided into a control interval and a data interval.

The control interval and the data interval can be allocated by adjusting the time allocation ratio according to the configuration of the video wireless relay system and the amount of traffic.

The access point may reallocate time slots according to the addition or deletion of one or more nodes of the plurality of nodes.

Wherein the plurality of wireless transmission paths includes a third wireless transmission path that does not require relaying, a second wireless transmission path that requires a one-hop relay, and a first wireless transmission path that requires a three- To form a plurality of communication links.

The access point can allocate dedicated time slots for each link and each camera.

The access point can set a bypass path by reallocating dedicated time slots for each link and each camera according to the quality status of the adjacent link.

The access point can reallocate dedicated time slots for each link and each camera according to a change in picture quality to adjust the throughput of the video data.

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The method according to an embodiment of the present invention may include the steps of (a) exchanging node information between an access point (AP) and a plurality of nodes through a control channel (C-CCH) ; (b) assigning a service channel (SCH) and a timeslot to the plurality of nodes by the access point; (c) switching the channel from the control channel (C-CCH) to the service channel (SCH) by the plurality of nodes; (d) performing the Dynamic Host Configuration Protocol (DHCP) procedure by the access point and the plurality of nodes; And (e) transmitting and relaying video data to the access point by the plurality of nodes, wherein (a) comprises: the access point establishing a plurality of communication links with the plurality of nodes in parallel have.

Preferably, the control channel, the service channel, and the timeslot are separated by a frequency division multiplexing (FDM) scheme and a channel and a time slot set in a TDM (Time Division Multiplexing) scheme at the separated channel frequency .

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In the step (b), the access point can allocate a dedicated time slot for each set link and each camera.

In the step (b), the access point can reallocate the timeslot as one or more nodes of the plurality of nodes are added or deleted.

Wherein the step (a) comprises: initializing the access point and the plurality of nodes by tuning to the control channel (C-CCH); Exchanging node information between the plurality of nodes over the control channel (C-CCH); The access point searching for a neighboring node on the control channel (C-CCH); And authenticating the neighbor node by the access point.

On the other hand, in the embodiment of the present invention, a computer-readable recording medium on which a program for realizing the respective video wireless relay method is recorded can be provided.

According to the embodiment of the present invention as described above, it is possible to overcome the limitations of the existing point-to-point wireless CCTV (the operation is restricted in a wireless network environment in which a large number of cameras are installed due to a large complexity in implementation) The camera can be managed wirelessly, and the wireless transmission distance can be extended.

In addition, according to an embodiment of the present invention, a wireless video communication network that overcomes a delay problem, which is a limit of a service provided in a conventional WLAN and guarantees quality of service (QoS), is constructed, There is an effect that can be used.

Further, according to the embodiment of the present invention, it is possible to eliminate the complexity of the wired line by installing a cable, and to reduce the cost.

In addition, according to the embodiment of the present invention, the bandwidth of the wireless channel on the wireless relay network can be continuously used without interruption, and thus it can be widely used for building a multimedia wireless communication service system in which a multimedia service is required. That is, the present invention can be applied to a streaming service in which a large amount of data and high image quality are required, such as a CCTV camera image.

1 is a block diagram of a video wireless relay system according to an embodiment of the present invention;
2 is a diagram illustrating a structure of a CCH (Control Channel) and an SCH (Service CHannel) defined in IEEE802.11P,
3 is a diagram illustrating a structure of a control channel (CCH) and a service channel (SCH) according to an embodiment of the present invention.
4 is a view for explaining a link connection of a relay node according to an embodiment of the present invention and a time slot division of a control interval and a service interval;
FIG. 5 is an overall flowchart of a video wireless relay method according to an embodiment of the present invention;
FIG. 6 is a detailed flowchart of a network joining process of a relay node in a video wireless relay method according to an exemplary embodiment of the present invention.
FIG. 7 is a detailed flowchart of a channel allocation process in the video wireless relay method according to an exemplary embodiment of the present invention;
8 is a detailed flowchart of a video data transmission and relay process in the video wireless relay method according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings, It can be easily carried out. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

And throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "electrically connected" with another part in between. Also, when a component is referred to as " comprising "or" comprising ", it does not exclude other components unless specifically stated to the contrary . In addition, in the description of the entire specification, it should be understood that the description of some elements in a singular form does not limit the present invention, and that a plurality of the constituent elements may be formed. In addition, since the number of nodes, the number of channels, the number of time slots, and the like in the description of the entire specification are arbitrarily shown for the sake of understanding, the present invention is not limited thereto. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, the technical point of the present invention will be described in order to facilitate understanding of the embodiment of the present invention.

In the embodiment of the present invention, a plurality of CCTV cameras are remotely installed, and the wireless transmission distance is extended by a wireless relaying method in order to transmit the CCTV video which can not be transmitted to the control center, and the wireless relay network is divided into a frequency division multiplexing (FDM) Time Division Multiplexing), and relay the CCTV image through a plurality of channels on the established wireless relay network.

In the embodiment of the present invention, IEEE802.141 and IEEE802.11P are modified to support streaming service of security video (CCTV video in surveillance area) requiring high quality, high quality of service (QoS) (CCTV video) by extending the wireless coverage (wireless transmission distance) by constructing a wireless relay network by separating the channel frequency by using the channel frequency and setting a plurality of channels and time slots in the separated channel frequency by the TDM method. .

That is, in the embodiment of the present invention, the N nodes including the CCTV camera and the wireless transmission control unit are connected to each other through the wireless relaying method, and the CCTV video is transmitted to the control center in such a manner that the wireless transmission distance is extended. For example, the Nth node (the end node) located farthest from the control center transmits its CCTV image to the (N-1) th node adjacent to the control center side than itself, and the (N-1) Multiplexes the CCTV image taken by itself and the CCTV image received from the N-th node, and transmits the multiplexed CCTV image to the (N-2) th node adjacent to the control center side to the control center, which is the final destination.

More specifically, the video wireless relay system according to an embodiment of the present invention includes an access point (AP) on the control center side for controlling a wireless communication network, a CCTV camera for capturing an image and a wireless relay function A plurality of wireless relay nodes for multiplexing the CCTV image received from the previous node and the CCTV image taken by the relay node and relaying the same to the access point (AP) side, and a plurality of wireless relay nodes And is wirelessly relayed within the area.

Here, the access point (AP) allocates and manages a channel to each node, and dynamically allocates a channel according to the operation of the CCTV camera such as addition or deletion of a node. The wireless transmission control unit installed in each node subscribes to the network according to the network registration procedure using the channel allocated from the access point (AP), and relays and transmits the control data and the service data.

In this case, in order to support the radio relay function, the frequency band is divided into I channels (I is a natural number) at intervals of 20 MHz, and all channels are divided into one CCH (Control Channel) and a plurality of SCH CHannel). The SCH includes a C-SCH (Control Service CHannel) and a D-SCH (Data Service CHannel). The CCH (Control Channel) includes a C-CCH (Common Control CHannel) Lt; / RTI >

In the embodiment of the present invention, a link from an access point (AP) to a node is referred to as a downlink, and a link from a node to an access point is referred to as an uplink.

1 is a block diagram of a video wireless relay system according to an embodiment of the present invention.

As shown in FIG. 1, the control center 100 manages a surveillance area through a CCTV image received through each path. At this time, the monitoring system 102 provided in the control center 100 monitors the CCTV images received through the respective paths. Since the control center 100 and the monitoring system 102 are well known in the art, they will not be described in detail here.

An access point (AP) 101 is connected to the control center 100. The access point 101 allocates channel information (channel and time slot) to each node and manages the allocated channel And dynamically allocates channel information according to addition or deletion of nodes. That is, the access point 101 performs a function of reallocating time slots according to the addition or deletion of nodes in order to efficiently use the time slots. At this time, the channel information is information for allocating a channel frequency by a FDM (Frequency Division Multiplexing) method and setting and allocating a plurality of channels and a time slot by a TDM (Time Division Multiplexing) method to a separated channel frequency.

In FIG. 1, three wireless transmission paths (path 1, path 2, path 3) are shown as an example. One of the nodes 7 170 is provided on a path 3 that does not require a relay, and two nodes 5, 6 (150, 160) are provided on a path 2 that requires a relay of one hop. And four nodes 1, 2, 3, and 4 (110, 120, 130, and 140) are connected in series in a path 1 that requires a three-hop relay. From the viewpoint of connection of the access point 101, three wireless transmission paths are connected in parallel.

The CCTV camera 172 and the wireless transmission control unit 171 are provided at the node 7 170 and the CCTV cameras 152 and 162 and the wireless transmission control units 151 and 162 are also connected to the nodes 5 and 6 The CCTV cameras 112, 122, 132 and 142 and the wireless transmission control units 111, 121, 131 and 141 are also connected to the nodes 1, 2, 3 and 4 (110, 120, 130 and 140) Respectively. Here, each CCTV camera has a codec function for capturing a corresponding surveillance area and also encoding a photographed image, and each wireless transmission control unit performs a network registration procedure using a channel allocated from the access point 101 And relays and transmits control data and service data (CCTV video).

Next, the CCTV video relaying and transmitting process in the path 1 will be described. In the CCTV video relaying and transmitting process in the path 1, the node 4 (140, the terminal node) located farthest from the control center 100 transmits the CCTV image photographed by itself The node 3 130 multiplexes the CCTV image captured by the node 3 130 with the CCTV image received from the node 4 140 and transmits the multiplexed CCTV image to the node 2 (130, wireless relay node) The node 2 120 transmits the CCTV image captured by itself, the CCTV image received from the node 3 130 (the CCTV image captured at the node 4, and the CCTV image captured at the node 3) The node 1 110 transmits the CCTV image of itself and the CCTV image received from the node 2 120 to the neighboring node 1 (110, wireless relay node) 4 CCTV Young , In such a way that by a multiplex CCTV images) shot in a CCTV image and the node 2, node 3, taken in the transmission to the access point 101 in the upward direction, and transmits to the control center 100 is the final destination.

Also, the two nodes 5 and 6 (150 and 160) located at the path 2 transmit the CCTV image to the node 6 (160) -> the node 5 (150) -> the access point 101 in the same wireless relaying manner, The node 7 (170) located on the path 3 transmits the CCTV image to the access point 101 directly without passing through the relay.

As described above, in the embodiment of the present invention, the wireless relay network is constructed in a structure that can be connected to the access point 101 through various wireless transmission paths (path 1, path 2, path 3) Can be constructed.

FIG. 2 is a structure diagram of a CCH (Control Channel) and an SCH (Service CHannel) defined in IEEE802.11P. In FIG. 2, an IEEE802.11P Standard channel structure and frequency spectrum.

As shown in FIG. 2, the IEEE 802.11P standard includes one CCH (Control CHannel) having a 10 MHz frequency band and six SCHs (Service CHannel) having a 10 MHz frequency band. In other words, it consists of 7 channels and 70MHz frequency band. At this time, CCH is used for system control and safety driving service, and SCH is used for data service such as IP traffic.

The channel time includes a control channel interval and a service channel interval. For example, the channel time is initialized to 50 ms each. At this time, the control channel interval and the service channel interval form a synchronization interval.

At this time, all devices in the control channel interval have to be set to the CCH (control channel), and a warning message, a high priority message and a control message are exchanged through the CCH (control channel) during this period. During the service channel interval, non-safety services such as Internet service can be selectively exchanged through a service channel (SCH).

In the following embodiment of the present invention, the CCH and the SCH are switched in a frequency division manner and are communicated. Therefore, it is desirable to allocate the channel information so that the frequency-to-frequency switching is minimized in the device (each node).

FIG. 3 is a structure diagram of a CCH (control channel) and a SCH (service channel) according to an embodiment of the present invention. FIG. 3 illustrates one CCH, a D-SCH (Data Service CHannel) And a channel structure and a frequency spectrum of four SCHs including a C-SCH (Control Service CHannel).

As shown in FIG. 3, one CCH 310 has a 20 MHz frequency band and includes a C-CCH 311. Each of the four SCHs 320 has a frequency band of 20 MHz and includes a D-SCH 321 and a C-SCH 322. That is, it consists of 5 frequency channels and 100MHz frequency band.

The SCH 320 includes a C-SCH 322 used for control and a D-SCH 321 used for data, and is divided into a C interval (Control Interval) 331 and a D interval (Data Interval) 332). The frame interval 330 includes a C-CCH and a D-SCH 311 and 322 or a C-SCH and a D-SCH 321 and 322.

In an embodiment of the present invention, the time allocation between the C interval 331 and the D interval 332 is adjusted and allocated at an appropriate ratio according to the configuration of the video wireless relay system and the amount of traffic. For example, the time allocation between the C interval 331 and the D interval 332 is adjusted and allocated at a ratio of 10 ms: 90 ms.

All the devices (access point and each node, etc.) are initially tuned and initialized to the CCH 310, and each node is assigned a frequency channel from the access point 101. [ In the video wireless relay system, the traffic is composed of the downlink from the access point 101 to the node and the uplink from the node to the access point, and since the amount of traffic will mostly go uplink, the time between the downlink and uplink The ratio is allocated, for example, at a ratio of 1:99, but can be changed (adjusted) according to the number of relay hops and the number of CCTV cameras.

FIG. 4 is a diagram for explaining a link connection and a control interval of a relay node according to an embodiment of the present invention and a time slot division of a service interval. In FIG. 4, And a scenario in which a control interval 442 and a service interval 471 are divided into time slots.

As shown in FIG. 4, for example, seven CCTV cameras are connected to a path 430 having a 0-hop relay, a path 420 having a 1-hop relay, and a path 410 having a 3-hop relay It is connected and operated. And one control channel and two service channels. The control channel can be divided into one time slot (441), and each service channel is divided into seven time slots (451 to 457, 461 to 461, 467).

At this time, in the case of the path 430 having the 0-hop relay, since the CAM-7 image (image photographed by the 7th CCTV camera) is transmitted to the access point 101 directly without passing through the relay, Occupies.

In the scenario of the path 420 having the one-hop relay, the CAM-6 image (the image photographed by the sixth CCTV camera) is transmitted to the access point 101 via the CAM-5 (the fifth CCTV camera). At this time, the CAM-6 image is transmitted to CAM-5 via the uplink between CAM-6 and CAM-5, and one time slot 467 is required. The CAM-5 transmits the CAM-6 image received from the CAM-6 to the one time slot 462 required for relaying through the uplink between the CAM-5 and the access point 101, One time slot 464 required to transmit the uplink data between the CAM-5 and the access point 101 on the uplink. As a result, a total of three time slots are required in the path 420 having the one-hop relay.

When the procedure used in the path 420 having the one-hop relay described above is applied to the path 410 having the three-hop relay, a total of ten time slots 451 to 457, 461, 463 and 465 are required.

Therefore, according to each scenario described above, one time slot is required in the path 430 having the 0-hop relay, three times in the path 420 having the one-hop relay and ten times slots in the path 410 having the 3-hop relay , A total of 14 time slots are required.

By allocating dedicated time slots for each link and each CAM as described above, the link characteristics can be grasped and utilized for controlling the image quality, and information can be prevented from being mixed. Accordingly, it is also possible to reassign dedicated time slots for each link and each CAM according to the quality status of the adjacent links, thereby setting a bypass path. In order to improve the reception quality according to the change in image quality, it is also possible to reassign dedicated time slots for each link and each CAM to adjust the throughput of the image.

FIG. 5 is a flowchart illustrating an image wireless relay method according to an exemplary embodiment of the present invention. Referring to FIG. 5, each device (each node) joins a network to form a wireless relay network, And shows an operation procedure for relaying.

First, all devices (access point and each node, etc.) are initially tuned to CCH (i.e., C-CCH) and initialized.

Thereafter, the device (each node) that desires to join the wireless relay network accesses the C-CCH (i.e., C-CCH) to scan the beacon of the neighboring node, and if the beacon of the neighboring node is not received The beacon periodically broadcasts its own beacon (501) until the beacon of the adjacent node is received (502).

When the beacon of the neighboring node is received (502), the corresponding device (node) synchronizes with the neighboring node using the beacon information of the received neighboring node, and transmits its own beacon to the neighboring node (503), and node_info (n), which is its own node information, to neighboring nodes by broadcasting and receives node_info (504), which is node information of neighbor nodes, to exchange node information with neighbor nodes.

Then, the corresponding device (node) confirms that the access point 101 is found (505). If the access point 101 is not found, the device (node) proceeds to step 504 and the neighbor node transmits the node information When the access point 101 is found, the access point 101 performs a process of receiving authentication from the access point 101 (step 506). When the access point 101 starts to scan through the CCH (i.e., C-CCH) and finds a beacon of the neighboring node (step 505) Transmits its own beacon to the neighboring node and authenticates the neighboring node (506). The above steps 501 to 506 are performed through the C-CCH, and the process of establishing a link between the access point 101 and a plurality of nodes will be described in detail with reference to FIG.

Then, the access point 101 that has confirmed the link connection with each node allocates a SCH and a time slot to each node in the radio relay network 507. The nodes transmit the SCH from the CCH (i.e., C-CCH) (508).

Then, the nodes that have switched channels to the SCH request a DHCP (Dynamic Host Configuration Protocol) to the access point 101 through the C-SCH, and accordingly the access point 101 enters the DHCP procedure, And the DHCP procedure is completed (509). The above steps 507 to 509 are performed through the C-SCH, and the process of assigning channel allocation information to each node connected to the wireless relay network will be described in detail with reference to FIG.

Then, each node relays and transmits the CCTV image to the access point 101 (510). The above-mentioned " 510 "process is performed through the D-SCH, and the above-described image data transmission and relay process will be described in detail with reference to FIG.

FIG. 6 is a detailed flowchart of a network joining process of a relay node in a video wireless relay method according to an exemplary embodiment of the present invention, and shows a procedure for establishing a link between an access point (AP) and a plurality of nodes.

First, the access point 101 scans a beacon of a neighbor node-1 through a CCH (i.e., C-CCH) and periodically broadcasts its own beacon if the beacon is not received (601).

When the beacon of the adjacent node, node-1, is received, the access point 101 synchronizes with the node-1 using the beacon information of the received node-1, To the neighbor node-1 (602).

Then, the neighbor node-1 transmits the node information (node_info (AP)) to the access point 101 and its neighbor node-2 again (603). At this time, the node_info (AP) message transmitted by the neighbor node-1 to the access point 101 is a message confirming that the message transmitted by the access point 101 is well received, and the node_info Message is a message for transmitting the node information of the access point 101 and broadcasts the same node_info (AP) message to simplify the transmission procedure.

Then node-2 transmits the received node_info (AP) back to node-1 (604). At this time, the node_info (AP) message to be transmitted back to the node-2 is an acknowledgment signal that the node_info (AP) message transmitted by the node-1 is well received.

As described above, after propagating the node information of the access point 101 to the radio relay network, the node-1 adjacent to the access point 101 transmits its node information node_info (node-1) to the access point 101 (605) and receives node_info (node-1) from the access point (101) and node-2 again to confirm that the corresponding message is successfully received (606, 607) .

Then node-1 transmits node_info (node-2), which is its neighbor node information, to node-1 (608), and node-1 transmits node_info (node-2) And transmits it again to the access point 101 and the node-2 (609). At this time, the node_info (node-2) message transmitted by the node-1 to the node-2 is a message for confirming that the message transmitted by the node-2 is well received and the node_info (node- The message is a message for transmitting the node information of the node-2, and broadcasts the same node_info (node-2) message to simplify the transmission procedure.

Then, the access point 101 transmits the node_info (node-2) to the node-1 again, thereby confirming the received message to the node-1 (610). When the confirmation is completed, the process proceeds to an authentication process of confirming whether the subscriber is legitimate.

The above operation can also be expanded and applied to the 3-hop relay. The configuration of the wireless relay network is completed by extending the operation procedure to the N nodes.

FIG. 7 is a detailed flowchart of a channel allocation process in the video wireless relay method according to an exemplary embodiment of the present invention, and shows a process of assigning channel allocation information to a CCTV camera (i.e., node) connected to a wireless relay network.

First, the access point 101 transmits a beacon to the node-1, which is the closest node, to predict a channel allocation. Then, the node-1 transmits a beacon to the access point 101 and the node-2 to transmit a response message to the access point 101, and transmits this information (channel assignment notice information) to the node-2, Prepare to receive information. Then, node-2 transmits beacon to node-1 and transmits a response message (701).

Then, the access point 101 notifies the Node-1 that the channel assignment information will be transmitted by transmitting the assign-info-req message, and when receiving the assign-info-ack message as the response message to the Node- 1 to assign the channel information (allocate the SCH and the time slot) (702).

When the channel assignment process of the node-1 is completed as described above, the access point 101 also allocates channel information to the node-2 (703). In other words, the access point 101 transmits an assign-info-req message to node-2 through node-1 to notify that channel allocation information is to be transmitted, and transmits an assign-info-ack message, (703) allocates channel information (SCH and time slot) by transmitting an assign-info-conf message to node-2 through node-1. As such, since the access point 101 can not directly communicate with the node-2, the node-1 relays the information.

At this time, each node that has been allocated channel information switches the channel from the CCH (i.e., C-CCH) to the SCH.

When the process of allocating channel information is completed, the access point 101 performs the DHCP procedure from the closest node-1 to the node-2 far from the node-1 (704, 705). For example, when the node-1 transmits a DHCP discover message to the access point 101, the access point 101 transmits a DHCP offer message to the node-1 so that the node-1 transmits the DHCP offer message to the access point 101 When the DHCP request message is transmitted, the access point 101 transmits a DHCP ack message to the node-1 (704). The node-2 and the access point 101 perform the same DHCP procedure through the information relay of the node-1 (705).

FIG. 8 is a detailed flowchart of a video data transmission and relay process in a video wireless relay method according to an exemplary embodiment of the present invention. Referring to FIG. 8, each node connected to a wireless relay network transmits video data photographed by a CCTV camera to an access point And transmits and relays through the corresponding channel using the allocated channel information.

First, the access point 101 transmits a beacon to the closest node, node-1, node-1 transmits a beacon to the access point 101 and node-2, node-2 transmits a beacon to node- And prepares to transmit and relay the video data (801).

Then, node-1, which is a neighbor node of the access point 101, first transmits the video data of its own to the access point 101 through the channel and time slot allocated to it, using the channel information allocated from the access point 101 (802), and relays the image data of the node-2 transmitted from the node-2 to the access point 101 through the relay procedure (803). At this time, the relay procedure is performed through the allocated channel and the time slot using the channel information from the access point 101. [

By repeating the above-described image transmission and relay process (804 to 806), the CCTV image can be transmitted and relayed.

Meanwhile, the video wireless relay method according to the present invention as described above can be implemented in the form of a program command that can be executed through various computer means and recorded in a computer readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. The medium may be a transmission medium such as an optical or metal line, a wave guide, or the like, including a carrier wave for transmitting a signal designating a program command, a data structure, or the like. Examples of program instructions include machine language code such as those generated by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Various permutations, modifications and variations are possible without departing from the spirit of the invention.

Therefore, the scope of the present invention should not be construed as being limited to the embodiments described, but should be determined by the scope of the appended claims, as well as the appended claims.

Claims (23)

In a video wireless relay system,
An access point (AP) for dynamically allocating channel information to a plurality of nodes and receiving image data from the plurality of nodes through a plurality of wireless transmission paths; And
And a plurality of nodes for transmitting and relaying video data through the plurality of wireless transmission paths using channel information allocated from the access point,
The channel information is information for allocating a channel frequency by a frequency division multiplexing (FDM) scheme and setting and allocating a plurality of channels and a time slot in a TDM (Time Division Multiplexing) scheme to the separated channel frequency,
The plurality of nodes relay and transmit control data and video data while switching channels between the CCH and the SCH according to the channel information allocated from the access point,
Wherein the access point is connected in parallel with the plurality of wireless transmission paths and communicates with the plurality of nodes via the plurality of communication links.
In a video wireless relay system,
An access point (AP) for dynamically allocating channel information to a plurality of nodes and receiving image data from the plurality of nodes through a plurality of wireless transmission paths; And
And a control center for managing the surveillance area through the video data received through the access point,
Wherein the plurality of wireless transmission paths transmit and relay video data in a wireless relaying manner,
The channel information is information for allocating a channel frequency by a frequency division multiplexing (FDM) scheme and setting and allocating a plurality of channels and a time slot by a time division multiplexing (TDM) scheme to the separated channel frequency,
Wherein the plurality of nodes relay and transmit control data and video data while switching channels between the CCH and the SCH according to the channel information allocated from the access point,
Wherein the access point is connected in parallel with the plurality of wireless transmission paths and communicates with the plurality of nodes via the plurality of communication links.
In a video wireless relay system,
A plurality of nodes for transmitting and relaying video data through a plurality of wireless transmission paths using channel information allocated from an access point,
Each of the nodes comprising:
An imaging means for imaging and encoding an image; And
And a wireless transmission control unit for relaying and transmitting control data and video data using channel information allocated from the access point (AP)
The channel information is information for allocating a channel frequency by a frequency division multiplexing (FDM) scheme and setting and allocating a plurality of channels and a time slot by a time division multiplexing (TDM) scheme to the separated channel frequency,
Wherein the plurality of nodes relay and transmit control data and video data while switching channels between the CCH and the SCH according to the channel information allocated from the access point,
Wherein the access point is connected in parallel with the plurality of wireless transmission paths and communicates with the plurality of nodes via the plurality of communication links.
The method of claim 3,
The video wireless relay system includes:
And adjusts the time allocation ratio between the downlink and the uplink according to the number of relay hops and the number of the photographing means.
3. The method according to claim 1 or 2,
Each of the nodes comprising:
An imaging means for imaging and encoding an image; And
A wireless transmission control unit for relaying and transmitting control data and video data using channel information allocated from the access point (AP)
And a video wireless relay system.
4. The method according to any one of claims 1 to 3,
The plurality of nodes comprising:
An Nth node (N is a natural number) for transmitting the image data of the node itself to the (N-1) th node located at the longest distance from the access point and adjacent to the access point side than the node itself, (N-1) -th node for transmitting and relaying data and image data received from the N-th node to an (N-2) -th node adjacent to the access point on the side of the And a first node for transmitting and relaying the video data photographed by the wireless relay node and the video data received from the second node to the access point, Video wireless relay system.
4. The method according to any one of claims 1 to 3,
Wherein the plurality of channels comprises:
A video wireless relay system comprising one CCH (Control CHannel) and a plurality of SCH (Service CHannel).
8. The method of claim 7,
The CCH includes a C-CCH (Common Control CHannel)
Wherein the plurality of SCHs comprises a plurality of C-SCH (Control Service CHannel) and D-SCH (Data Service CHannel).
9. The method of claim 8,
Wherein the plurality of C-SCHs and the D-SCHs are divided into a control interval and a data interval, respectively.
10. The method of claim 9,
Wherein the control interval and the data interval are < RTI ID =
Wherein a time allocation ratio is adjusted and allocated according to a configuration of the video wireless relay system and an amount of traffic.
4. The method according to any one of claims 1 to 3,
The access point comprising:
And reassigns time slots according to addition or deletion of one or more of the plurality of nodes.
4. The method according to any one of claims 1 to 3,
Wherein the plurality of wireless transmission paths includes a third wireless transmission path that does not require relaying, a second wireless transmission path that requires a one-hop relay, and a first wireless transmission path that requires a three- And forming a plurality of communication links, including the communication links.
4. The method according to any one of claims 1 to 3,
The access point comprising:
And assigning dedicated time slots for each link and each camera.
14. The method of claim 13,
The access point comprising:
And allocates a dedicated time slot for each link and each camera according to the quality status of the adjacent link to set a bypass path.
14. The method of claim 13,
The access point comprising:
And reallocates dedicated time slots for each link and each camera according to a change in picture quality to adjust a throughput of the video data.
delete In a video wireless relay method,
(a) establishing a link between an access point (AP) and a plurality of nodes by exchanging node information through a control channel (C-CCH);
(b) assigning a service channel (SCH) and a timeslot to the plurality of nodes by the access point;
(c) switching the channel from the control channel (C-CCH) to the service channel (SCH) by the plurality of nodes;
(d) performing the Dynamic Host Configuration Protocol (DHCP) procedure by the access point and the plurality of nodes; And
(e) transmitting and relaying video data to the access point by the plurality of nodes,
Wherein the step (a) sets the access point in parallel with the plurality of nodes and the plurality of communication links.
18. The method of claim 17,
Wherein the control channel, the service channel,
Wherein a channel frequency is separated by an FDM (Frequency Division Multiplexing) scheme, and a channel and a time slot are set in a TDM (Time Division Multiplexing) scheme at the separated channel frequency.
delete 18. The method of claim 17,
The step (b)
Wherein the access point allocates a dedicated time slot for each link and each camera.
18. The method of claim 17,
The step (b)
Wherein the access point reallocates the timeslot as one or more of the plurality of nodes are added or deleted.
18. The method of claim 17,
The step (a)
Initializing the access point and the plurality of nodes by tuning to the control channel (C-CCH);
Exchanging node information between the plurality of nodes over the control channel (C-CCH);
The access point searching for a neighboring node on the control channel (C-CCH); And
Wherein the access point authenticates the neighbor node
/ RTI > A computer-readable recording medium having recorded thereon a program for realizing the video wireless relay method according to any one of claims 17, 18, 20 and 22.

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