KR101604694B1 - Method of messages exchanging and transmitting devices and receving devices - Google Patents

Abstract

A first identifier for identifying the transmitting device from an AVC (Audio Video Control) layer in a medium access control (MAC) layer for the purpose of measuring a round trip time between receiving devices in a wireless network transmission device, Receiving an echo request message including a second identifier and a third identifier for the first identifier; Constructing a MAC message including a message preamble, a message type, and the echo request command in the MAC layer and delivering the MAC message to a physical layer; Transmitting to the receiving device a first physical layer data unit including at least one header, the MAC message, and audio / video (A / V) data at the physical layer; And receiving a second physical layer data unit including an echo report message including the third identifier in response to the echo request command from the receiving device .

WHDI, Echo Request Message, Echo Report Message, A / V Data, Identifier

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a message exchanging method and a transmitting /

The present invention relates to a message exchange method and a transmission / reception device, and more particularly, to a method for exchanging messages between devices in a wireless network and a transmission / reception device therefor.

Recently, with the development of communication, computer and network technology, many kinds of networks have been developed and implemented in real life. While networks have large networks that connect the world, such as wired or wireless Internet, there are small wired or wireless networks that connect home appliances in a limited space, such as a typical home or workplace. As the kinds of networks have become diverse, interfacing technologies have been also diversified so that communication between networks and networks or between devices and devices can be performed.

1 is a diagram schematically illustrating an example of a WVAN (Wireless Video Access Network), which is a kind of wireless private access network (WPAN).

WVAN is a wireless network capable of supporting the uncompressed transmission of 1080P A / V streams by establishing a wireless network between digital devices in a limited space of 10m or less such as the home, securing a throughput of 4.5 Gbps or more at a bandwidth of about 7 GHz, to be. Therefore, it is a network constituted by individual devices within a limited space, and it is possible to communicate seamlessly between applications by configuring a network by directly communicating between devices.

Referring to FIG. 1, a WPAN includes two or more user devices 11 to 15, and one of the devices operates as a coordinator 11. The regulator 11 serves to provide the basic timing of the WPAN and to control quality of service (QoS) requirements. Devices that can be used as devices include computers, PDAs, notebooks, digital TVs, camcorders, digital cameras, printers, microphones, speakers, headsets, barcode readers, displays, mobile phones and all digital devices.

The high-capacity video bus uses a high-speed digital signal transmission method of 1 Gbps or higher to transmit high-definition audio data of 1080p or more on the HD screen. However, since such a high capacity video bus is transmitted through a specific cable connected between the devices, there is a growing demand for transmitting data of a high-speed A / V bus in real time over the air. There is an advantage that the cable can be reduced when transmitting data of high-speed A / V bus wirelessly and there is no distance limitation between devices. However, in the case of WLAN (IEEE802.11), since the A / V data and other data are regarded as common data in the physical layer system, the object of transmitting the data of high speed A / V bus wirelessly is achieved There is a difficulty.

WVAN (Wireless Video Access Network), which is a kind of wireless private access network (WPAN), treats A / V data and other data as the same general data in the physical layer system, There is a difficulty in achieving the object of transmitting data on the bus.

Accordingly, there is a need for a test for an efficient radio path performance test for A / V data transmission in a wireless network.

SUMMARY OF THE INVENTION The present invention is conceived to solve the problems as described above, and it is an object of the present invention to provide a method of performing a radio path performance test by performing a Round Trip Time (RTT) test through exchange of a specific message between user devices.

It is another object of the present invention to provide a method for reducing message loss due to throughput overflow by adjusting a message transmission interval based on a prediction of a maximum transmission capacity for a radio path between user devices.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, unless further departing from the spirit and scope of the invention as defined by the appended claims. It will be possible.

According to another aspect of the present invention, there is provided a method for exchanging messages between a receiving device and a recipient device in a wireless network, Receiving an Echo Request message including a first identifier for identifying the transmitting device from the Audio Video Control layer, a second identifier for identifying the receiving device, and a third identifier; (MAC) message including the message preamble, the message type, and the echo request message, and transmitting the MAC message to the physical layer. In the physical layer, at least one header, the MAC message, and the audio / ) ≪ / RTI > to the receiving device; Seen from the device in response to the Echo-Request message includes receiving a second physical layer data unit comprising a report message echo (Echo Report Message) containing the third identifier.

The MAC message may be multiplexed with the A / V data in the physical layer, and the at least one header includes a basic header and an extended header, . The MAC message may include a CRC (Cyclic Redundancy Check) code added in the MAC layer for error detection in the receiving device.

The message type included in the MAC message may indicate that the echo request message is an AVC command.

Preferably, the first physical layer data unit is a downlink physical layer data unit (DLPDU) and the second physical layer data unit is an uplink control physical layer data unit (ULCPDU) UNIT). Alternatively, the first physical layer data unit is an uplink control physical layer data unit (ULCPDU) and the second physical layer data unit is a downlink physical layer data unit (DLPDU) Lt; / RTI >

The at least one header included in the first physical layer data unit may include time information for synchronization and a list of devices constituting the wireless network.

Here, the first physical layer data unit may be transmitted during a time interval including a first time interval in which the MAC message and the at least one header are transmitted and a second time interval in which the A / V data is transmitted , And the second physical layer data unit may be transmitted during the first time interval.

According to another aspect of the present invention, there is provided a transmitting device for a wireless network, including a first identifier for identifying a transmitting device, a second identifier for identifying a receiving device, A MAC layer for generating a MAC message including an AVC layer for generating an Echo Request message including the identifier, a message preamble, a message type, and the Echo Request message received from the AVC layer, and at least one header, Generating a first physical layer data unit including audio / video (A / V) data and transmitting the first physical layer data unit to the receiving device, receiving, in response to the echo request message, And a physical layer for receiving a second physical layer data unit including the second physical layer data unit.

Wherein the physical layer is capable of multiplexing the MAC message with the A / V data, and the at least one header includes a basic header and an extended header, . The MAC layer may add a CRC code to the MAC message for error detection in the receiving device, and the message type included in the MAC message may indicate that the echo request message is an AVC command.

Preferably, the first physical layer data unit is a downlink physical layer data unit (DLPDU), and the second physical layer data unit is an uplink control physical layer data unit (ULCPDU). Alternatively, the first physical layer data unit may be an uplink control physical layer data unit (ULCPDU), and the second physical layer data unit may be a downlink physical layer data unit (DLPDU).

The at least one header included in the first physical layer data unit may include time information for synchronization and a list of devices constituting the wireless network.

According to another aspect of the present invention, there is provided a transmission device of a wireless network including a receiver for receiving a broadcast signal, a decoder for decoding a broadcast signal received by the receiver, A first physical layer data unit including a display unit for displaying a content according to the broadcast signal added and decoded, a MAC message including a broadcast signal and a message preamble received by the receiver, a message type, and an echo request message A network control module for receiving and processing a second physical layer data unit including an echo report message from the receiving device in response to the echo request message, Through the exchange of reporting messages To store a broadcast signal and measuring the round trip time between the receiving device or the receiving unit receives from the transmission device to the local storage device or a control unit for controlling to reproduce the content stored in the local storage device. Here, the echo request message may include a first identifier for identifying the transmitting device, a second identifier for identifying the receiving device, and a third identifier.

According to another aspect of the present invention, there is provided a method of exchanging messages for measuring a round trip time between transmitting devices in a receiving device of a wireless network, Generating an echo report message including an identifier included in the echo request message to respond to the request message, constructing a MAC message including a message preamble, a message type, and the echo report message in the MAC layer, And transmitting to the transmitting device a physical layer data unit including at least one header, the MAC message, and audio / video (A / V) data in the physical layer.

According to another aspect of the present invention, there is provided a receiving device for a wireless network, the receiving device comprising: a receiving unit configured to receive an echo request message transmitted from a transmitting device, A MAC layer for constructing a MAC message including the message preamble, the message type, and the echo report message and transmitting the MAC message to the physical layer, at least one header, an MAC message and an audio / (A / V) data, and transmits the physical layer data unit to the transmitting device.

According to the present invention, an efficient message exchange can be performed by performing a Round Trip Time (RTT) test through a specific message exchange between user devices. This enables more efficient wireless path selection between devices in a wireless network, reducing message loss and transmitting / receiving wireless signals.

In addition, it is intended to reduce message loss due to throughput overflow by adjusting the message transmission interval based on the prediction of the maximum transmission capacity for the radio path between user devices.

The effects obtained by the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the following description will be.

In order to solve the above-mentioned technical problems, a method of checking a radio path performance for A / V data transmission in a wireless home digital interface (WHDI) wireless network is disclosed in embodiments of the present invention.

The following embodiments are a combination of elements and features of the present invention in a predetermined form. Each component or characteristic may be considered optional unless otherwise expressly stated. Each component or feature may be implemented in a form that is not combined with other components or features. In addition, some of the elements and / or features may be combined to form an embodiment of the present invention. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments.

The Wireless Home Digital Interface (WHDI) wireless system, which is being studied recently, is a technology for transmitting uncompressed A / V data in 5Ghz U-NII band. WHDI processes and modulates A / V data in consideration of human audiovisual characteristics at the PHY layer, thereby more efficiently converting high capacity video bus data to wireless. At this time, to evaluate the radio performance, a radar detection technique such as a radio signal intensity band of 5 GHz is applied to the receiving end. WHDI needs a technique that can appropriately evaluate the transmission performance of control data or non-A / V data. This is because it is possible to easily implement functions such as setting a radio path, setting a retransmission window, and evaluating a response performance of a host system.

At least one user device included in the WHDI includes a source device for transmitting A / V data and a sink device for receiving A / V data from the source device. Here, a source device that actually transmits A / V data may be referred to as an active source device, a sink device that receives an Audio / Video signal may not actually transmit A / V data, And a passive source device connected in series. Each device can be divided into at least three layers according to its function, and generally includes a PHY layer, a MAC layer, and an AVC layer.

2 is a diagram illustrating an embodiment of a broadcast signal processing system including a broadcast signal receiver as an example of a transmitting device in a WHDI network.

The broadcast signal receiver can reproduce A / V data received from a broadcasting station or a cable satellite via the antenna through the following process, In addition, when the broadcast signal receiver operates as a transmitting device on the WHDI network, it can remotely transmit the received A / V data to at least one receiving device.

Referring to FIG. 2, a broadcast signal processing system, which is an example of a transmitting device, includes a broadcast signal receiver 21 and a network device 24 connecting a broadcast signal receiver and a remote storage device or another device 25.

The broadcast signal receiver 21 includes a receiving unit 211, a demodulating unit 212, a decoding unit 213, a display unit 214, a control unit 215, a network control module 216, a graphics processing unit 217, (218) and a control signal communication unit (219). Here, in the example of FIG. 2, the local storage device 23 further includes a local storage device 23, which is connected to the interface 218 including the input / output port. However, Or may be a storage device mounted within the receiver 21.

The interface unit 218 can communicate with the wired or wireless network device 24 and can be connected to the at least one receiving device 25 existing on the wireless network through the network device 24. The control signal communication unit 219 receives a user control signal according to a user control device, for example, a remote controller 22, and outputs the received signal to the control unit.

The receiver 211 may be a tuner that receives a broadcast signal of a specific frequency through at least one of a terrestrial wave, a satellite, a cable, and the Internet. The receiving unit 211 may be provided for each of a broadcast source, for example, a terrestrial wave, a cable, a satellite, and a personal broadcasting, or may be an integrated tuner. If the receiver 211 is a tuner for terrestrial broadcasting, it may include at least one digital tuner and an analog tuner, or may be a digital / analog integrated tuner.

Also, the receiving unit 211 may receive an internet protocol (IP) stream transmitted through wired / wireless communication. When receiving the IP stream, the receiving unit 211 can process the transmission / reception packet according to the IP protocol that sets the source and destination information for the received IP packet and the packet transmitted by the receiver. The receiving unit 211 can output the video / audio / data stream included in the received IP packet according to the IP protocol, and can generate and output the transport stream to be transmitted to the network as an IP packet according to the IP protocol . The receiving unit 211 is a component for receiving an externally input video signal. For example, the receiving unit 211 may receive a video / audio signal input in the IEEE 1394 format from the outside or a stream in a format such as HDMI.

The demodulator 212 demodulates the input broadcast signal in the reverse of the modulation scheme. The demodulator 212 demodulates the broadcast signal and outputs a broadcast stream. When the receiving unit 211 receives the stream format signal, for example, when receiving the IP stream, the IP stream bypasses the demodulation unit 212 and is output to the decoding unit 213.

The decoding unit 213 includes an audio decoder and a video decoder and decodes a broadcast stream output from the demodulation unit 212 or a stream reproduced through the network control module 216 using respective decoding algorithms, . In this case, a demultiplexer (not shown) may be further provided between the demodulator 212 and the decoder 213 to demultiplex each stream according to the identifier. The demultiplexer demultiplexes the broadcast signal into an audio element stream (ES) and a video element stream (ES), and outputs the audio signal to the respective decoders of the decoding unit (213). Also, when a plurality of programs are multiplexed on one channel, only a broadcast signal of a program selected by the user can be selected and divided into a video element stream and an audio element stream. If the demodulated broadcast signal includes a data stream or a system information stream, it is separated from the demultiplexer and transmitted to the corresponding decoding block (not shown).

The graphic processing unit 217 may process graphics to be displayed so that a menu screen or the like can be displayed on a video image displayed by the display unit 214 and control the graphics to be displayed on the display unit 214 together.

The interface unit 218 may interface with at least one receiving device 25 through a wired or wireless network. Examples of the interface unit 218 include an Ethernet module, a Bluetooth module, a local wireless Internet module, a portable Internet module, a home PNA module, an IEEE 1394 module, a PLC module, a home RF module, and an IrDA module. On the other hand, the interface unit 218 can output a control signal for turning on the power to the remote storage device. For example, although not shown in FIG. 2, the interface unit 218 may turn on a remote storage device by transmitting a WOL signal to a network interface unit through which a separate remote storage device communicates.

The network control module 216 transmits the broadcast signal received by the receiver 211 to the other device on the WHDI network when the broadcast signal receiver 21 shown in FIG. Lt; RTI ID = 0.0 > physical < / RTI > The network control module 216 may receive the broadcast signal directly from the receiver 211 or receive the demodulated broadcast signal from the demodulator 212. In the former case, the encoding process may be omitted. The broadcast signal received by the receiver 211 may be input to the protocol module 216 through a process for signal transmission in the control unit 215 and the like. For example, when receiving a message including a broadcast signal from the receiving device 25, the received message is separated into a broadcast signal and a MAC message by the network control module 216, May be input to the decoding unit 213, decoded by a decoding algorithm, and then output to the display unit 214.

The network control module 216 includes an AVC layer for generating a predetermined AVCL command, a MAC layer for generating a MAC message including an AVCL command transmitted from the AVC layer, And a PHY layer for generating a first physical layer data unit including the received broadcast signal and the MAC message. The first physical layer data unit may be transmitted to another device using the network device 24 via the interface 218. [ In addition, the network control module 216 may receive the second physical layer data unit including the response message transmitted by the receiving device that has received the AVCL command in response thereto.

2, the control unit 215 and the network control module 216 are separately provided for convenience of explanation, but they may be implemented as one system chip as indicated by a dotted line. Specifically, in the protocol layer including the AVC layer, the MAC layer and the PHY layer to be controlled by the network control module 216, the AVC layer and the MAC layer transmit the message to be transmitted or the received message to the controller 215 Discrimination can be made. At this time, the PHY layer forms a blur layer data block in the network control module 216. The details of the network control module 216 will be described later with reference to the physical layer data block structure disclosed in Figs. 9 to 16 below.

The control unit 215 can control operations of the illustrated components (receiving unit, demodulation unit, decoding unit, display unit, graphics processing unit, network control module, interface unit) and the like. Then, a menu for receiving a user's control command is displayed, and an application for displaying various information and a menu of the broadcast signal processing system to the user can be driven.

For example, the control unit 215 may read contents stored in the local storage device 23 when the local storage device 23 is mounted. The control unit 215 can control the local storage 23 to store the broadcast content received from the receiver 211 when the local storage 23 is mounted. In addition, the control unit 215 may output a signal for controlling the local storage device 23 to mount according to whether or not the local storage device 23 is mounted.

The control unit 215 checks the remaining storage capacity of the local storage 23 and displays the information on the display unit 214 through the display unit 214 or the graphic processing unit 217 . If the remaining storage capacity of the local storage device 23 is insufficient, the controller 215 may transfer the content stored in the local storage device 23 to the remote storage device. In this case, when the remaining storage capacity of the local storage device 23 is insufficient, the control unit 215 instructs the user to connect the local storage device 23 to another local storage device (not shown) or a remote storage device through the display unit 214 A menu indicating whether or not to store the stored content is displayed. Then, the control signal of the user can be received and processed. Accordingly, the control unit 215 may move and store contents stored in the local storage 23 and other directly or remotely mounted storage devices with each other.

The display unit 214 can display the broadcast content received from the receiver 211 and the content stored in the local storage 23. According to a control command of the control unit 215, a menu for displaying information relating to whether or not the storage device is mounted and remaining capacity is displayed and can be operated according to the control of the user.

3 is a diagram illustrating an example of a protocol layer structure implemented in a device in the WHDI system, which is performed in the network control module 216 of FIG.

Referring to FIG. 3, the WHDI system may include four layers.

The application layer 31 at the highest level is a layer for the user to integrate WHDI in the host system of the user.

The AVCL layer (Audio Video Control Layer) 32 is an upper layer responsible for streaming connection and device control for A / V data transmission between a source device and a sink device. AVCL is used to indicate the active source device for which the sink device wishes to receive the A / V stream from a particular source device. The sink device may not need to receive and render the A / V stream or receive the A / V stream any more. On the other hand, the source device is used to indicate a particular display that the user has requested to display the content on the display part of the source device. Alternatively, the source device may be used to determine the capacity associated with the A / V data of the sink device or to transmit metadata associated with the A / V data. Alternatively, all devices are used to perform Remote Device Control (RDC), such as controlling playback or channel variation of a disc player on a set top box.

As such, AVCL includes two types of control schemes: control protocol and metadata delivery. Here, the control protocol (or AVCL protocol) includes the transmission of bi-directional commands between devices on an active network. Generally, a message including an AVCL command is transmitted through a MAC layer, mapped to a MAC message, and mixed with other data in a PHY layer, and will be described later.

Next, the MAC (Media Access Control) layer 33 is responsible for functions such as link setup, connection or disconnection, channel access to the lower layer of the data transmission protocol, and reliable data transmission. That is, it plays a role of transmitting a control / data message or controlling a channel.

The MAC layer uses a CSMA / CA (Carrier Sence Multiple Access with Collision Avoidance) using an ACK frame as a basic channel access scheme, and performs subcarrier detection or CCA (Clear Channel Assessment) before sending a packet . Then, the directionality between the source device and the sink device is considered, and the downlink and uplink are classified. The entire downlink is implemented as one long frame, and the process of receiving and recovering the ACK frame may be omitted. In the downlink, since the synchronization is performed between the video frame to be transmitted and the modem (PHY) frame, the transmission time is determined according to the format of the A / V data to be transmitted. In general, the entire MAC format includes a Basic Header (BH) and an Extended Header (EH).

Next, the PHY layer 34 can directly process the A / V data and be processed by the MAC layer 33 at the same time. In the WHDI, the PHY layer is responsible for transmitting and receiving unmodulated A / V data. The PHY layer switches the requested message from the upper layer such as the AVCL layer 32 and the MAC layer 33 to take charge of the wireless signal so that the request message can be transmitted between the devices by the physical layer . In addition, the PHY layer has the capability to transmit A / V data in unidirectional and bi-directional data channels, PHY level encryption and SNR of all A / V data, carrier detection and interference detection Measurements are also possible.

The PHY layer receives or outputs various types of pre-processed video data samples or pre-processed audio data samples in the form of Y, Cb, and Cr streams of 4: 4: 4 ratio of pixels in each source / sink device. In this form all transitions are performed in the application layer 31 on each source / sink device.

4 is a block diagram showing an example of a source device in the WHDI system.

4, a host controller 41, which is a kind of processor, integrally manages the entire system and performs a role of an AVCL layer or a WHDI baseband module 43 as an I2C (Inter Integrated Circuit) Bus system structure. Since the I2C bus system operates on the I2C protocol, a plurality of ICs can connect and communicate with each other via a common structured bus. The I2C bus system provides a way to connect (i.e., provide communication between) a central processing unit (CPU) and associated peripheral ICs in a television environment, which is widely used in consumer electronic devices. The I2C system is generally limited to transmit data at a set clock rate in accordance with the setup protocol, and the main controller IC of the I2C system sets the data rate or rate (i.e., clock rate or bus speed). Thus, all of the ICs connected to a particular I2C bus must communicate at the same rate or data rate. The host control unit 41 may include a memory therein or may use an external memory.

Next, the WHDI baseband module 43 plays the role of the MAC / PHY layer and receives A / V data from the A / V source 42 via a bus such as LVDS, (IF) to the receiver (44). The WHDI RF module 44 converts the intermediate frequency IF into a carrier signal and transmits the converted microwave signal through the multiple antennas 45. It is also possible to receive not only transmission but also reception of control signals other than A / V data.

5 is a diagram showing an example of a sink device in the WHDI system.

Referring to FIG. 5, the host controller 51, which is a kind of processor, plays a role of integrating applications like the above-described source device and connects the WHDI baseband module 54 to the I2C (Inter Integrated Circuit) bus system structure As shown in FIG. The WHDI RF module 53 converts the RF signal received from the multiple antennas 52 into an intermediate frequency (IF), restores the A / V data transmitted from the source device, and outputs the LVDS, I2S or other A / V bus signals.

6 is a diagram illustrating a process of converting a general video signal including a Vertical Blanking Period into an RF signal in a WHDI device in an A / V data transmission / reception operation.

Generally, a period in which a source device continuously transmits a radio signal to a sink device is referred to as a downlink interval. In this interval, a downlink PHY data unit (DLPDU) is transmitted. The downlink interval can be divided into a vertical blanking period interval 61 and an active video interval 62. The Vertical Blanking Period section 61 includes a section 611 for transmitting a downlink preamble including a CES (Channel Estimation Sequence) to a sink device and a section 612 for transmitting a downlink header ). The CES is a technique for measuring a distortion of a received signal that occurs when a transmission signal passes through an unspecified radio channel, that is, a time delay, a phase shift, and an attenuation using a pilot signal included in a transmission signal and having a predetermined pattern. In the Active Video section 62, the source device transmits the A / V data to the sink device.

The WHDI source device in the A / V data transmission / reception operation can continuously transmit the 5 GHz band signal including the control information and the video data corresponding to the radio signal during the downlink interval. The time required for the downlink section corresponds to a sum of a part of a normal vertical blanking period section of a video bus (component, HDMI, LVTTL, etc.) and an active video section in which actual video data is transmitted. That is, the signal transmission time is determined according to the type of data transmitted from the source device, so that the PHY signal in the downlink interval can be transmitted in units of 10 ms or longer in comparison with other RF communication.

The downlink interval continues to the uplink interval. The uplink interval is a period during which the PHY layer of the sink device can transmit a radio signal to the source device. The uplink interval is only a part 63 of a normal vertical blanking period of a video bus (component, HDMI, LVTTL, etc.). The uplink control PHY data unit (ULCPDU), which is an uplink section, includes an RF turn around section 631, a section 632 for transmitting a preamble including a CES, a section for transmitting an uplink header 633, a section 634 for transmitting uplink data, and a section + slience + RF turnaround section 635.

The interval 632 for transmitting the uplink preamble including the CES is a signal interval for synchronization of the device receiving the uplink radio signal. The RF turn-around section 635 corresponds to the time required for switching the transmitting antenna to the receiving antenna or converting the receiving antenna to the transmitting antenna. That is, the Slience + RF Turn Around interval 635 is a period of time to stop temporarily. In case of the sink device, it corresponds to the time required to switch from the transmission mode to the reception mode and the source device to switch from the reception mode to the transmission mode.

When the uplink interval ends, the preamble / CES transmission interval 611 and the downlink header transmission interval 612 of the downlink interval continue to fill the Vertical Blanking Period interval 61.

The WHDI PHY layer in the A / V transmission operation can specify the lower transmission interval according to the time composition of the original signal (signal of the wired bus) of the video data to be transmitted (that is, the interval between the vertical blanking period section and the active video section) have. In the downlink and uplink, each transmission interval is transmitted using OFDM and MIMO techniques, but the PHY signal generation and transmission methods are different from each other.

The source device configures its own voice, video, and control data into a DLPDU using a downlink interval comprised of a Vertical Blanking Period section 61 and an Active Video section 62 in the PHY layer, and then transmits the DLPDU to the sink device as a radio signal . The section is mainly divided into a Video Dependent DLPDU mode for transmitting only video data and a Video Independent DLPDU mode for transmitting data not related to video data, and will be described with reference to FIGS. 7 and 8. FIG.

7 is a diagram illustrating an example of a DLPDU sequence when the WHDI PHY layer is in Video Independent DLPDU mode.

Referring to FIG. 7, when a source device starts a network, it broadcasts its presence through a Video Independent DLPDU that is independent of A / V data in order to find a sink device. Video Independent DLPDU is similar to a beacon message but time information for synchronization or control information such as a device list of the network is loaded in the basic header BH and the extended header EH of the DLPDU so that other types of MAC commands or AVC commands There is a difference that they can be transmitted simultaneously. Another objective of the Video Independent DLPDU is to shorten the time required for transmitting only the audio signal to the sink device. Video Independent DLPDUs require a relatively short time of less than 5ms since they do not need to be synchronized to the video bus signal.

Referring to FIG. 7, when the source device transmits an independent DL PDU without A / V data to search for a sink device, the frequency F _DLI [0] represents different center frequency ranges within the 5 GHz U-NII range. For example, within a 5 Ghz U-NII range, F _DLI [0] is 5150 MHz and F _DLI [1] is 5470 MHz. The source device broadcasts its information over all channels, thereby inducing a sink device in a receiving standby state to respond.

8 is a diagram illustrating an example of a DLPDU sequence in a video dependent DLPDU mode in a WHDI PHY layer.

Referring to FIG. 8, the purpose of the Video dependent DLPDU is to cause the source device to synchronize its frequency to the video signal prior to the wireless signal. For example, if the source device is transmitting a 1080p 50hz video signal to the sink device using the downlink, the DLPDU signal is transmitted for about 18ms, which is a signal period when the active source device, i.e., the DE signal, It continues. As shown in FIG. 8, when the first DLPDU is transmitted, the direction of the signal is changed, and the first sink device transmits Uplink Control PHY Data Unit (ULCPDU) data using the uplink to the source device. Thereafter, when the ULCPDU signal transmitted from the first sink device is transmitted to the source device, the next DLPDU signal is transmitted, and then the ULCPDU signal is transmitted from the second sink device to the source device. The header information of the ULCPDU and the DLPDU are transmitted in the vertical blanking period of the video signal. That is, the sink device can transmit the PHY signal for a relatively short time within 500 us.

9 is a diagram showing an example of a PHY structure for transmitting a DLPDU in the WHDI system.

The wireless encoding process in the DLPDU PHY structure of the WHDI active source device can be variously implemented depending on the type of data to be transmitted. In particular, in the case of video data, each frame (for example, each image) is decomposed into one or more color components (Y, Cb, Cr), and the frame of decomposed color components is decomposed into frequency components and then quantized. Here, the error of the quantization result is divided into a video fine stream and a quantized frequency component into a video coarse bitstream. The video quantization error stream and the video quantization coefficient bitstream are the same A channel encoding process different from that of the video data is also applied.

Referring to FIG. 9, the data transmitted in the WHDI DLPDU PHY structure includes data / control bitstream, which is the message command data requested by the MAC and AVCL layers, A test bitstream, which is a constant bit pattern mixed with the data, an audio bitstream that transmits audio data, and a video bitstream that transmits video data. The video bit stream may be divided into a video quantization coefficient bit stream for transmitting quantized video data and a video error bit stream, which is a bit stream of an error value corresponding to each quantized data.

The video quantization coefficient bit stream is a bit stream composed of quantized coefficients after de-correlating transform (DCT) of video data. The video quantization error bit stream is a quantization error generated after DCT transforming video data .

9, the audio data and the video data are transmitted through the encoders 71 and 72, respectively, and the other data are transmitted through the encoders 71 and 72. In this case, Control data such as a data / control bit stream and a test bit stream are transmitted to the bit stream MUX 73 without going through an encoding process. The video quantization coefficient bit stream among the video data is also transmitted to the bit stream MUX 73 after encoding, so that a total of four signals are combined into one bit stream. At this time, the video dependent DLPDU mode includes the video quantization coefficient bit stream, but when the independent DLPDU mode, the quantization coefficient bit stream is excluded.

Next, the quantization coefficient stream encoder 74 combines all the data except for the header information (BH, EH) into a single bitstream in the bitstream MUX 73, and outputs it to the AES-128 system Encrypt. The bitstream processor 75 modulates the encrypted signal into a wireless signal based on the QAM scheme and adds an error correction code.

On the other hand, the video quantization error is processed independently by the quantization error data processing and encryption module 76 to transmit data more securely, unlike the above-mentioned four pieces of data. At this time, the fine data processing and encryption module 76 includes a fine-data scaling module, a fine-data symbol mapper, a quantization error data A fine-data encryptor and a quantization error data scrambler.

In the above example, five pieces of data, which have undergone the above-described separate processing, are divided into video quantization error data through the quantization error data processing and encryption module 76 and the remaining four pieces of data Are input to the MIMO-OFDM mapper 77. [ The MIMO OFDM mapper 77 distributes the input signal to the RF-chain module 78 transmitted through the sub-carriers or the respective transmit antennas in order to apply MIMO based on antenna diversity, channel matrix calculation and inverse transformation. Here, dedicated subcarriers can be assigned to carrier signals having different center frequencies according to a video quantization coefficient and a video quantization error.

In the Nth transmit chains 78, the downlink IDFT unit 781 performs a process of converting the signals of the finally calculated subcarriers into time axes and integrating them. CP Inserter 782 performs a process of copying a block of a predetermined size back to the previous symbol of the previous symbol to avoid multi-path interference that may occur between OFDM symbols. The preamble Mux 783 rearranges the signals so that only the preamble data is transmitted in the preamble transmission periods 611 and 632 shown in FIG. In the Symbol Shaper (784), the signal intensity in the frequency domain is processed so as to be included in the spectral mask required by the WHDI system. The final signal is converted into an analog signal through a digital / analog converter in an analog and RF module (785), and the converted intermediate frequency (IF) is converted into a radio signal (RF) in a 5GHz band through a mixer And transmitted through an antenna.

In the above, the process of transmitting audio and video signals through the antenna through the DLPDU PHY structure in the WHDI system was examined.

In short, the active source device of WHDI always performs DCT conversion on the video data directly input from the PHY layer before radio signal transmission. Then, by quantizing the DCT-transformed video data, it is possible to compress the transmission data in effect and transmit more data within a limited bandwidth. The quantized video data is separated into video quantization coefficient data and video quantization error data, and different error correction coding processes are applied. Alternatively, a different modulation scheme may be applied to the separated video quantization coefficient data and video quantization error data.

Hereinafter, each component in the subsystem of the DLPDU PHY layer of the WHDI active source device will be described in more detail.

10 is a diagram showing the structure of an audio encoder in an example of a DLPDU PHY structure of a WHDI active source device.

Referring to FIG. 10, the audio encoder 71 is composed of an audio external encoder (Audio Outer Encoder) 711 and an audio byte interleaver (Audio Byte Interleaver) 712. An audio external encoder (Audio Outer Encoder) 711 uses Read-Solomon as a preprocess for audio data. The polynomial used is P (x) = 1 + x ^ 2 + x ^ 3 + x ^ 4 + x ^ 8. For example, 16 bytes of the same value are added to 239 bytes of data, Produce the result. This result is again mixed with the convolutional byte-interleaver in the Audio Byte Interleaver (712), which can reduce the distortion of the speech signal caused by the radio error.

11 is a diagram showing a structure of a video encoder in an example of a DLPDU PHY structure of a WHDI active source device.

The video encoder 72 performs DCT on the uncompressed Y, Cb, and Cr video data (e.g., pixel) in the frequency domain, divides the converted signal into a DC component and an AC component, quantizes them, And extracts an error occurring in the quantization process as a video quantization error stream. Then, the quantized value is extracted as a video quantization coefficient bit stream. After the frequency is DCT-transformed, a high energy coefficient of a frequency component as low as the number proportional to the usable transmission amount measured in the MAC layer is selected and transmitted to a unit performing the next process, and the remaining signal is discarded.

More specifically, referring to FIG. 11, all pixels are first grouped into 8x8 blocks in the block grouping unit 721 for DCT conversion of video data. For example, when block grouping is performed on pixels of 1920x1080 full HD size, they can be grouped into 240x135 blocks. Because it is grouped into 8x8 blocks, the horizontal blanking of the video bus must be buffered at least 8 times in the transmitting video memory.

The block interleaver 722 interleaves the rows and columns of each block as shown in FIG. 12 for 240x135 blocks or some blocks in the full screen of, for example, 1920x1080 full HD size in order to avoid cluster error. interleaving, and mixing. 12 is a diagram showing an example of block interleaving performed by the video encoder shown in FIG.

Next, in the spatial de-correlation module (723) for performing the DCT transform, the block interleaver (722) converts DCT transformed frequency components into respective blocks whose column and row permutations are changed. That is, a spatial de-correlation in each block is performed to generate a set of coefficients for each block. The signal transformed into the frequency component has a different process according to the value of the corresponding coefficient. Referring to FIG. 11, a block type detector (block type detector) 726 for inputting a coefficient and analyzing a coefficient according to a coefficient value and inputting it to a coefficient parsing and selection module 726 or determining a type of each block is provided. And a block parsing mode controller 725 for controlling the processing mode of each block to input a coefficient parsing and selection module 726.

The Block Type Detector 724 finds the type of each video block. At this time, two types of block types can be defined as type 0 and type 1. In general, a block having a low energy in a high frequency coefficient after being subjected to the DCT conversion is set to type 0, and a block having a high energy in a high frequency coefficient can be set to a type 1. This particular block type determination criterion can be a specific performer capable of satisfying the required image quality.

Next, the block processing mode controller 725 applies one of the first mode and the second mode to all the blocks to perform a process. The first mode is applied to all blocks in the basic mode while the second mode is applied to the blocks which are not changed through the number of consecutive video frames in the refinement mode. The decision criterion for the mode of processing a particular block may be a specific performer capable of meeting a video quality requirement. In the first mode, a high-frequency component is selectively discarded and a quantization process is applied to the DCT-converted video signal, so that a relatively small amount of video data can be generated. On the other hand, in the second mode, a relatively large amount of image data can be transmitted through the DCT-transformed video signal by selectively discarding high-frequency components and extracting quantization and error signals. However, in order to apply the second mode when the source device transmits video data, the sink device must support the second mode. Uncompressed transmission is possible if the second mode procedure is applied to all blocks and there is no process of discarding high frequency components.

Next, in the coefficient parsing and selection module 726, the block type determined by the block type detector 724 is performed in a block processing mode controller 725 The coefficient relating to the video quantization error stream of each block based on the block processing mode control instruction, the coefficient information table for selecting a proper coefficient, and the available bandwidth provided by the MAC layer.

In the MAC layer, N _{Coeffs _ per _ Block} is set. N _{Coeffs _ per _ Block} is the value of the per-block coefficient, which is determined by combining the current radio reception sensitivity and other performance values. For example, when the distance between the source device and the sink device is long and the radio channel condition is not good, the N _{Coeffs_per_Block} value is set to a small value so that high frequency components in the coefficients are automatically discarded.

Next, the coefficient quantizer 727 includes a block type detector 725, a block processing mode controller 725, and a coefficient parsing and selection module 725. And quantizes the signal transmitted from the signal processor 726. Based on the type of each block, the detailed control indication information, the appropriate quantization table, the available bandwidth provided by the MAC layer, etc. to generate a video quantization coefficient bit stream and a video quantization error stream for a complex symbol value The coefficients of each block can be quantized.

A subset of the DCT coefficients is quantized for each video block. Each quantized coefficient is represented in two types, such as a sequence of one or more quantized bits and a video quantization error coefficient (video fine coefficient). The unquantized coefficients remain unchanged and are referred to below as video quantization error coefficients.

The quantization process performed in the coefficient quantizer 727 may be performed as follows.

_, 그것의 출력 비트의 개수에 따라 각각의 양자화가 특정된다.1) N kinds of standard quantization can be DCT used for the DC component of the signal. For example,

_, Each quantization is specified according to the number of its output bits.

_, 그것의 출력 비트의 개수에 따라 각각의 양자화가 특정된다. 2) Three kinds of non-standard quantization can be used for DCT coefficients for non-DC components, that is, AC components. For example,

_, Each quantization is specified according to the number of its output bits.

로 양자화되고, 상기 양자화는

에 따른 N-bit 양자기에 의해 양자화된다고 가정한다. 양자화 과정은 다음과 같다.Each of the N-bit quantization coefficient is defined as 2 ^N quantized region containing the 2 ^N N -bit sequences each corresponding to one each of the 2 ^N quantized values, and a quantized region of the quantized region. DCT coefficients

, And the quantization is

Is quantized by an N-bit positive magnetism according to the following equation. The quantization process is as follows.

가 주어진 양자화 영역

을 찾는다. 수학적으로, 이것은

에 따라 수행된다. (where if means if and only if)1) Coefficient

Lt; / RTI >

. Mathematically,

. (where if means and only if)

에 해당하는 양자화 값인

를 산출하기 위해 계수

를 양자화한다.2) Quantization area

Which is a quantization value corresponding to

≪ / RTI >

Lt; / RTI >

를 생성한다. 상기 N-bit 시퀀스는 스트림에서 가장 먼저 출력되는 b₀비트를 포함하는 양자화 과정에서의 비트 시퀀스 출력이다.3) The N-bit sequence corresponding to the quantization region

. The N-bit sequence is a bit sequence output in a quantization process including b ₀ bits output first in a stream.

에 따라 정의되는 양자화 오류를 계산한다. 상기 양자화 오류는 양자화 과정에서 생성되는 비디오 양자화 오차 계수이다. 4)

Lt; / RTI > The quantization error is a video quantization error coefficient generated in the quantization process.

이 되고, 비트 시퀀스는 생성되지 않는다. For non-quantized coefficients,

And a bit sequence is not generated.

Hereinafter, the quantization bits calculated for each video block will be described with reference to FIG. 13 is a diagram showing quantization bits generated per video block in the DLPDU PHY structure of the WHDI active source device.

The selection of the quantized coefficients and the number of bits can be allocated according to a first block mode (Basic mode) or a second block mode (Refinement mode), a video format and a bandwidth limitation, The video block processed according to the mode is set to zero.

_And, all number of blocks the entire quantized by the MAC layer is N _{Bits per _ _ Block -} is set to be. The MAC layer also sets the value of the parameter N _{Bits _ per _ Block -} to be greater than or equal to 0 and less than 64. The value of the parameter N _{Bits _ per _ Block -} is used for rate adjustment by adding a single bit having a value of '0' to the first video block N _{Bits_fraction-} in all groups of 64 video blocks . At this time, the rate adjustment is started from the first video block by acquiring the bit rate of a constant constant when the average is equal to or larger than 64 video block groups. These bits are referred to as rate adjustment bits. When a rate adjustment bit is added, all the output bits of the block are added after the quantization. The bits generated for each video block must be predetermined by a type bit indicating the type of video block. If the type bit is calculated, it must be performed prior to quantization and rate adjustment of any bits. The type bit should have a value of '0' for the type 0 block and a value of '1' for the type 1 block.

The processing bits indicating the processing of the video block must be set prior to the type bit, the quantization bit and the rate adjustment bit. The processing bits are set to '0' in the source devices of all blocks when transmitting a signal to a sink device that does not support the second block mode.

After the quantization is performed, it is extracted into a video quantization error stream which is a difference between the quantized coefficient and the value before the quantization is performed.

Next, the bitstream MUX 73 multiplexes the four bitstreams (data / control bitstream, audio encoder output bitstream, video quantization coefficient bitstream, and test bitstream) into one quantization coefficient bit stream (coarse stream) Mix to process. At this time, header information (BH, EH) is excluded from the control information. The coarse stream encoder 74 encodes the video quantization coefficient bit stream excluding the header information (BH, EH) processed as one stream in the bitstream MUX 73.

Next, the bitstream processor 75 will be described with reference to FIG.

14 is a diagram illustrating a bitstream processor in an example of a DLPDU PHY structure of a WHDI active source device.

The bitstream processor 75 includes a TAIL Bits Inserter 751, a Convolution Encoder 752, a Bit Interleaver 753, a Symbol Mapper 754, a Symbol Parser 755, and a Space Time Block Code (STBC) .

The video quantization coefficient bit stream allows the error correction code to be transmitted rather than the video quantization error stream. Referring to FIG. 14, a convolution encoder 752 and an STBC (Space Time Block Code) encoder 756 add an error correction code to the video quantization coefficient bit stream. At this time, not only the video quantization coefficient bit stream, but also other data streams which are mixed in the bit stream MUX 73 and passed through the encryption process are also passed through the bit stream processor.

TAIL Bits Inserter (751) adds '0' as the last bit to receive the input of the Convolution Encoder. Encoding rates of 1/2, 3/4 and 5/6 are used in each encoder, which can be selected differently depending on the radio conditions, such as 1/2 if the radio is good and 5/6 if it is bad. The bit stream passed through the convolution encoder 752 is evenly spread out to adjacent bits in a bit interleaver 753. The symbol mapper 754 converts the video quantization coefficient bit stream into an IQ quadrature-phase coefficient in order to convert it into an analog signal. As shown in FIG. 15, the bit stream of the quantization coefficient stream is always encoded with 16-QAM can do.

15 is a diagram illustrating a 16QAM array for transforming into a coefficient of IQ quadrature phase of a quantization factor stream in an example of a DLPDU PHY structure of a WHDI active source device. In the 16QAM, each of the four bit strings is converted into one symbol.

16 is a diagram illustrating an example of a process of parsing an OFDM symbol in a symbol parser in an exemplary DLPDU PHY structure of a WHDI active source device.

A DLPDU symbol parser 725 distributes the 16-QAM symbols sequentially for each subcarrier and spatial stream (tansmit chain) assigned to the quantized coefficient stream for the modulated symbol stream.

The DLPDU uses a large number of spatial streams because it has a larger transmission amount than the uplink data (200 Mbps or more in the case of 1080p). Referring to FIG. 16, the DLPDU symbol parser 725 converts an input sequence of an IQ complex signal into a vector such as an OFDM symbol, a subcarrier, and a spatial stream.

For example, assuming that there are four MIMO channels, Nsym OFDM symbols, and Nscc subcarriers, the input data Complex 0, Complex 1, ... , Complex T, ... The OFDM symbol # 1, the subcarrier # 1, the spatial stream # 1, the subcarrier # 1, the subcarrier # 1, the spatial stream # OFDM symbol # 1, Subcarrier # 2, Spatial Stream # 1, Subcarrier # 2, Spatial Stream # 1, <OFDM symbol # 2, Subcarrier # 1, SpatialStream # 1>, <OFDM symbol # 2, Subcarrier # 1, SpatialStream # 2> The OFDM symbol # Nsym, the subcarrier # Nscc, the SpatialStream # 3, the OFDM symbol # Nsym, the subcarrier # Nscc, and the SpatialStream # 4.

The STBC encoder 756 shown in FIG. 14 adds redundant error correction codes for each spatial stream to further enhance the error correction possibility.

Next, the quantization error data processing and encryption process performed in the fine data processing and encryption module 76 will be described with reference to FIG.

17 is a diagram showing a quantization error data processing and encryption module in an example of a DLPDU PHY structure of a WHDI active source device.

The video quantization error data stream passed through the video encoder 72 is first subjected to a quantization error data scaling process in a quantization error data processing and encryption module 76. A quantization error data scaling module (fine-data scaling module 761) for quantizing error data scaling applies different scaling factors depending on whether each video block grouped by 8x8 is type 0 or type 1. For example, for a video block of type 0, all quantization error data included is multiplied by 1.75, and for a video block of type 1, all quantization error data included are multiplied by 1 to adjust the size.

Thereafter, the resized video data is subjected to a symbol mapping process in the symbol mapper 762. The quantization error data modulation process is distinguished from general digital / analog modulation (BPSK, QPSK, QAM) and the like. First, one quantization error data stream is grouped into two quantization error data, for example a quantization error for a Y component and a quantization error for a chroma component in one pixel. After the quantization error data processing and the encryption process are both performed in two groups, one modulation symbol includes two quantization error data. The first quantization error data has a real value and the second quantization error data has an imaginary value. In the modulation process, the (±) sign uses the sign before modulation, and the modulation uses the synthesis method of the quadrature phase carrier. For example, if the size of each IQ is ± 2047 and the maximum available value of the quantization error data is 1007.5, the first data is +22 and the second data is -24, then I = (22 * 2) +32 = 76 and Q = -24 * 2) + 32 = -80. This is advantageous in that the data of the quantization coefficient data stream such as 16QAM or 64QAM can be represented by one symbol more than twice as much as the modulation method of the quantization coefficient data stream. As described above, when modulating the quantization error data in the active source device, one of the quantization error data elements corresponding to the Y, Cb, and Cr components of one pixel is not decomposed into I and Q components. Instead, one quantization error data element is concatenated with an I component and one quantisation error data element is concatenated with a Q component.

Thereafter, the quantization error data coder 763 uses the modulated symbol as a complex input signal and encrypts it according to the key set in the quantization error data coder using the AES-128 CTR scheme. The encrypted complex output signal is dispersed by a fine-data scrambler 764 to avoid cluster errors.

Next, the MIMO-OFDM mapper 77 maps the symbols of the complex-valued quantized-coefficient-data complex value, symbols of the complex-valued error data, symbols of the fixed-time data streams, Map the pilot. In addition, a specific subcarrier is allocated as a fixed pilot and a subcarrier for a fluctuating pilot, and the receiver performs time synchronization or channel measurement using the subcarrier.

The preamble MUX 783 multiplexes the preamble field and the remaining fields (CES, BH, EH, IQ, DATA) to generate the entire DLPDU. When designing the preamble field, the preamble is selected as the input signal. On the other hand, when designing the other fields (CES, BH, EH, IQ, DATA), the output of the OFDM modulator is selected as the input signal.

The symbol shaper 784 performs the spectral mask shown in FIG.

18 is a diagram showing an example of the spectrum at the time of DLPHY RF transmission in the WHDI active source device.

The overall transmitted baseband signal consists of all field contributions. Here, the following equation (1) is satisfied.

는 각각

의 필터링된 버전이다. Symbol shaper(784)에서 산출되는 DLPHY 신호는 도 18에 도시된 바와 같은 Spectral Mask 최대치의 주파수 특성을 갖는다. here,

Respectively

Lt; / RTI &gt; The DLPHY signal calculated by the symbol shaper 784 has the frequency characteristic of the maximum spectral mask as shown in FIG.

Next, the uplink, which is a section for transmitting the PHY signal from the sink device or the passive source device to the active source device in the WHDI system, will be described.

As described above, the active source device is a source device that transmits video data or audio data to one or more devices, and the passive source device is a source device that is additionally connected to the active source device without transmitting video data. A sink device is also a device that receives video data or audio data from an active source device. Hereinafter, the sink device will be considered as including an active source device.

In the PHY interval, the uplink interval is divided into a mode for generating an uplink independent PHY data unit (ULIPDU) and a mode for generating an uplink control PHY data unit (ULCPDU).

The ULIPDU sends a signal to the sink device to inform its presence by traversing several channels within the 5Ghz UNII band in order to discover the source device in a state where the MAC device is not connected to any source device. The ULC PDU is a PHY mode in which a wireless device connected to an active source device avoids a DLPDU and transmits a control signal to another device using a short time, as described above with reference to FIG.

Specifically, ULIPDU generation will be described with reference to Figs. 19 to 23. Fig.

19 is a diagram showing an example of a form in which a ULIPDU is transmitted from a sink device to a source device in a WHDI system.

The ULIPDU is similar to the Video Independent DLPDU independent of the video data and has a relatively long signal period. The ULIPDU is a method of transmitting multiple signals continuously or repeatedly transmitting a short pause period, and then receiving a response thereto. As shown in FIG. 19, for example, a ULIPDU signal of 8750 400 uS is transmitted for 3500 msec, followed by waiting for a signal response for 400 ms, and then a same set of 8750 ULIPDU signals is transmitted again. That is, the group of sink devices of the _ULIPDU forms a T _uli period and traverses the 5 GHz U-NII band frequency, such as Fuli [0] and Fuli [1], respectively, to induce a response of the source device.

20 is a block diagram of a transmitting device that performs ULIPDU transmission in the WHDI system.

The transmitting device that transmits the ULIPDU includes a bit stream processor 81, an OFDM mapper 82, an uplink IDFT (Downlink DFT) 83, a CP encoder 84, a preamble MUX 85, a Symbol Shaper 86, And an analog and RF module (87). Each component only processes data that is not audio data or video data. The data transmitted through the ULIPDU includes a device ID (6 bytes value), an ID of a device to be searched, a vendor ID, and the like.

In WHDI, each device in the address scheme has a unique ID, which is a 6-byte MAC address that identifies each WHDI device. In general, assuming a WHDI-HDMI bridge (adapter) as a basic device, a device attached to it (for example, DVD, STB, Blueray, etc.) is called a sub device and a 1 byte address called LSA . And, when the network is connected, 1 byte address of ANA (Active Network Address) is added to each WHDI device. In this way, each device can be distinguished based on the device address system composed of the <device ID, LSA, and ANA> pairs.

21 is a block diagram illustrating a bitstream processor of a transmitting device that performs ULIPDU transmission in a WHDI system;

가 된다. 변조된 심볼(복소수 신호)은 심볼 파서(812)를 통해 각각의 OFDM 심볼에 할당된다. 하나의 OFDM 심볼은 부반송파 개수만큼의 복소수 신호 입력을 할당할 수 있다. ULIPDU는 MIMO, STBC와 같은 다중 안테나 기술을 사용하지 않고 하나의 공간적 스트림, 공간 시간 스트림으로 전송된다. ULIPDU OFDM의 부반송파의 개수는 DLPDU OFDM의 부반송파 개수보다 상대적으로 적다. 이는 데이터 레이트가 1080p이상의 비디오 데이터 전송을 위해 200Mbps 이상의 전송량이 필요한 것에 비해 제어 신호의 필요 데이터량이 1Mbps 이하로 적기 때문이다.Referring to FIG. 21, the ULIPDU bitstream processor 81 includes a symbol mapper 811 and a symbol parser 812. ULIPDU data modulation performed in the symbol mapper 811 is performed using On-Off Keying (OOK). For example, when one phase carrier is used, the carrier magnitude (intensity) becomes 0 when the input bit is 0, and the carrier magnitude (intensity) becomes 1

. The modulated symbols (complex signals) are allocated to each OFDM symbol through a symbol parser 812. [ One OFDM symbol can allocate a complex signal input as many as the number of subcarriers. ULIPDU is transmitted in one spatial stream and space time stream without using multiple antenna techniques such as MIMO and STBC. The number of sub-carriers of ULIPDU OFDM is relatively smaller than the number of sub-carriers of DLPDU OFDM. This is because the amount of data required for control signals is less than 1 Mbps, compared to a case in which a transmission rate of 200 Mbps or more is required for transmission of video data having a data rate of 1080 p or more.

Next, the OFDM mapper 82 maps symbols and pilots of data complex values to subcarriers and OFDM symbols. It is also possible to generate the pilot.

In the WHDI system, the ULIPDU DFT module 83 actually has the function of DFT / IDFT and operates as a DFT when receiving in the downlink but as an IDFT when transmitting in the uplink. That is, when the sink device is used as a reference, the ULIPDU DFT module 83 operates as an IDFT when transmitting and as a DFT when receiving.

The ULIPDU CP Inserter 84 adds a cyclic period to the IDFT-transformed signal transmission process in order to avoid multi-path interference between symbols before and after OFDM. The ULIPDU Preamble MUX 85 generates a ULIPDU by performing a preamble field, a CES, and data multiplexing. When designing the preamble field, the preamble is selected as an input signal. On the other hand, when designing for CES data, a signal output from the OFDM modulator is selected as an input signal.

Thereafter, in the ULIPDU symbol shaper 86, symbol shaping is performed so as to satisfy the spectrum as shown in FIG. 22 is a diagram showing an example of a transmission spectrum in the case of 20 MHz in WHDI ULIPDU.

Next, the ULCPDU in the uplink will be described with reference to FIG. 23 to FIG.

Typically, the PHY is designed to provide ruggedness and flexibility to support data rates up to 100 Kbps for optimal operation in the home or office. At this time, various signal processing apparatuses including OFDM modulation and frequency diversity can be used. The PHY transmission can utilize 20 MHz bandwidth mode and 40 MHz bandwidth mode, two bandwidth modes are mandatory for all WHDI devices.

Sharing and coexistence of media with other devices in the 5 GHz band is an important issue to maintain high performance, as it avoids interference to other systems. ULCPDU modulation is designed to coexist with other existing devices through a variety of different means including carrier sense, automatic frequency selection, and transmission power control.

The ULCPDU is a period for transmitting data / control information from the sink device to the source device or from the passive source device to the active source device in the PHY related to the WHDI radio transmission using the uplink. That is, the ULCPDU is a PHY signal sent from the sink device or the passive source device to the other active source device, the sink device, or the passive source device after the sink device receives the DLPDU from the active source device. The sink device or the passive source device finds the active source device, then fixes the channel and sends the ULCPDU.

At this time, as shown in FIG. 23, the ULCPDU transmission can be transmitted only during a short time between transmission periods of DLPDUs. 23 is a diagram showing a form of transmitting a video signal according to time between DLPDU and ULCPDU in the WHDI system. As described above, the PHY signal transmission in the WHDI uses the 5 GHz band.

24 is a block diagram showing the configuration of a transmitting device for transmitting ULCPDU in the WHDI system.

The reference implementation of the ULCPDU baseband provides an RF signal as a reference to encode the incoming data / control bitstream.

The ULC PDU transmission device is similar to the structure of the ULIPDU transmission device described above in Fig. Referring to FIG. 24, a bitstream processor 91 for performing a process for processing an input data bitstream, an OFDM mapper 92 for mapping a processed signal into pilot and data modulation symbols, and mapping the processed signals to OFDM symbols An uplink IDFT (Downlink DFT) module 93 for converting one array point block into a time domain block, a CP Inserter 94 for adding a cyclic prefix to the modulated signal transmission, A Symbol Shaper 96 for shaping a symbol on the time domain to implement a required spectrum, a frequency corrector 97, and an analog and RF module (not shown) for performing the other fill or multiplexing, Analog and RF module 98). Here, unlike the ULIPDU transmission device structure, the frequency corrector 97 is a component included only in a ULCPDU transmission device, and performs frequency line-correction to correct a frequency offset between a transmitting device and a receiving device.

Specifically, the bit stream processor 91 includes a bit stream coder 911, a symbol mapper 912 and a symbol parser 913 as shown in Fig. 25 is a block diagram showing the configuration of a bitstream processor in a ULCPDU transmitting device in a WHDI system.

The bitstream coder 911 encrypts the data bitstream using the AES-128 CTR scheme. The symbol mapper 912 modulates the decoded data bit stream into a plurality of symbols by an on-off keying method as in the ULIPDU transmitter. Then, the symbol parser 913 determines how many OFDM symbols each symbol is included in.

Next, the frequency corrector 97 is implemented only in the ULCPDU transmitting device. Is applied prior to transmission via the analog and RF module (98) to compensate for the frequency offset between the ULCPDU transmitter and the target ULCPDU receiver.

The frequency compensation performed by the frequency corrector 97 is expressed by Equation (2).

은 MAC 계층에 의해 설정되는데, 타겟으로 결정한 ULCPDU 수신기를 포함하는 소스 디바이스로부터 수신받은 DLPDU에서 추정될 수 있다. 구체적으로,

은 ULCPDU 송신기와 타겟으로 삼은 ULCPDU 수신기 간 주파수 오프셋이 보상 이후 1325Hz 미만이 되도록 설정된다. ULCPDU의 아날로그 및 RF 모듈(Analog and RF module; 98)에서는 수신측에서 발생하는 수신장애에 따라 반송파 주파수를 1325Hz까지 유동적으로 조정할 수 있다.here,

Is set by the MAC layer and may be estimated in a DLPDU received from a source device including a ULCPDU receiver determined as a target. Specifically,

Is set such that the frequency offset between the ULCPDU transmitter and the targeted ULCPDU receiver is less than 1325 Hz after compensation. In the analog and RF module (98) of the ULCPDU, the carrier frequency can be flexibly adjusted to 1325 Hz according to a reception failure occurring at the reception side.

As described above, a source device that transmits A / V data among user devices belonging to WHDI and a sink device that receives A / V data have been described in detail. When signal splitting, DFT modulation and quantization are performed in a device having the above-described structure, A / V data is transmitted and received.

Meanwhile, two or more user devices belonging to WHDI can be divided into an active source device for transmitting A / V data, a sink device for receiving the A / V data, and a passive source device. Transmitted A / V data can be transmitted / received directly between devices as well as through multiple paths. Accordingly, a device that transmits a wireless signal can select a path capable of efficiently transmitting / receiving a signal through a performance check on one or more wireless paths.

Current WHDI does not have a message defined to run the Round Trip Time (RTT) test. RTT means the round-trip time from when a packet is transmitted on the transmitting side to the receiving side via any number of intermediate connection points or communication networks, and then the response signal reaches the transmitting side through multiple intermediate connection points or communication networks again. do. For example, in the case of the IP protocol, an ICMP (Ping) packet is defined and the same message is transmitted from the sender again, and the transmission delay (RTT) and the transmission success rate can be obtained with the information of the received packet. WHDI can also add a specific message that can act as an RTT in the wireless signal transmission and reception process.

Hereinafter, a message exchange method including an echo message as a specific message capable of performing an RTT function in the process of performing A / V streaming between a source device and a sink device according to an embodiment of the present invention will be described .

26 is a flowchart illustrating an echo message exchange process between a transmitting device and a sink device in a WHDI radio signal transmission / reception process according to an embodiment of the present invention.

The echo message may include an echo request message and an echo report message. The exchange of the echo request message and the echo report message may be performed by the active source device according to the subject to which the A / V data is to be transmitted, and vice versa.

Referring to FIG. 26, a transmitting device that transmits a signal may include one or more parameters corresponding to an identifier in an echo request message to transmit to an receiving device (S201). The receiving device having received the echo request message can transmit an echo report message including the same parameter as the identifier included in the echo request message to the transmitting device as a response message to the echo request message (S202). Then, it is possible to determine the inter-device connectivity test, the average communication rate assessment, and the round trip delay assessment based on the parameters.

Hereinafter, echo message exchange between the transmitting device and the receiving device will be described in more detail with reference to FIG. 2 and FIG.

2, a broadcasting signal receiving system including a broadcast signal receiver 21 of a transmitting device generates a signal including an echo request message in the network control module 216 and inputs the signal to the receiving unit 211 To the receiving device 25 together with the external broadcasting signal. In response to the echo request message generated by the receiving device 25, a wireless signal including an echo report message may be received. Hereinafter, a signal processing process performed by the network control module 216 will be described.

FIG. 3 shows an example of a WHDI sink device as an example of a receiving device and a WHDI source device as an example of a transmitting device among devices that transmit and receive wireless signals between devices of the WHDI.

The source device and the sink device exchange messages and data through the PHY layer 34 of the network control module 216, which can exchange AVCL messages with each other. For example, when an AVCL request message is to be transmitted from a source device to a sink device, the source device transmits the AVCL request message from the AVCL 32 of the source device to the sink device via the MAC layer 33 and the PHY layer 34. The sink device receives the transmitted AVCL request message at its PHY layer 34 and forwards it to the AVCL 32 via the MAC layer 33. The AVCL 32 of the sink device generates a response message in response to the request message transmitted from the source device and transmits the response message to the source device via the PHY layer 34 via the MAC layer 33 of the sink device.

More specifically, the AVCL protocol at the AVCL 32 of the sending device is based on a command or message exchange performed between WHDI subdevices. When the receiving device that receives the AVCL command requesting an action performs the requested action, it transmits an <Action Accept> message. If the requested action can not be performed or does not execute, a response message such as <Action Reject> . Also, if the device has too many parameters, the first expected parameter should be analyzed and the remaining parameters removed.

The AVCL command message transmitted through the transmitting device may include components as shown in Table 1.

Field Name Description Size Value Initiator_Addr Initiator_AVCL_Address 2 Bytes Byte 0: Initiator Device_ANA
Byte 1: Initiator Device_LSA
Follower_Addr
Follower AVCL_Address
2 Bytes Byte 0: Follower Device_ANA
Byte 1: Follower Device_LSA
AVCL_Opcode Opcode 1 Bytes AVCL_Parameter Parameter (s) specific to opcode (Optional, depending on opcode) Depends on Opcode

Referring to Table 1, one AVCL command message may be composed of AVCL_ parameters as a transmission device address (Initiator_Addr), a receiving device address (Follower_Addr), AVCL_Opcode, and an identifier. One or more devices included in the WHDI network need to be distinguished. In order to match the device address system described above, a bit indicating an address of a transmitting device and a receiving device must be added. The transmission device address (Initiator_Addr) is an address of a transmitting device that transmits an AVCL command, and has a size of 2 bytes consisting of 1 byte indicating an ANA (an address assigned by the active source device when the transmitting device is an active source device) and 1 byte indicating an LSA . The receiving device address (Follower_Addr) is a network address of the receiving device that receives the AVCL command, and similarly has a size of 2 bytes by allocating 1 byte to each of ANA and LSA. AVCL_Opcode indicates the type of the message, and when the transmitting device intends to transmit an echo request message to the receiving device, it indicates that the AVCL command is an echo request command. 1 byte is allocated to AVCL_Opcode.

If the AVCL command is an echo request command, an arbitrary parameter can be used within the 32-bit number limit. As shown in FIG. 26, when a transmitting device transmits an echo request message to a receiving device, the receiving device may include a predetermined parameter in the echo request message, and the receiving device, which has received the echo request message, The same parameter as the parameter may be included in the echo report message as a response to the echo request message and transmitted to the transmitting device. By using the same parameters, RTT can be derived through echo message exchange.

All AVCL commands generated in the AVCL 32 of the transmitting device are transmitted to the MAC layer 33 to be mapped to the MAC message in an equivalent type. An echo request message, which is a kind of AVCL command according to an embodiment of the present invention, is also transferred from the AVCL 32 to the MAC layer 33. The MAC message of the MAC layer 33 is substantially a medium for transmitting information between WHDI devices, and the type and length of the MAC message can be variously set according to the respective AVCL commands.

27 is a diagram illustrating a MAC message format present in the MAC layer 33 in a transmitting device. The MAC message type may be classified into a relatively short MAC message and a long MAC message depending on whether the Null field is included or not. The MAC message shown in FIG. 27 is a short MAC message excluding the Null field. The Null field is an area allocated to transmit a null message. The null field has a length of 1 byte and has a value of 0x00.

Referring to FIG. 27, a short MAC message includes a 2-byte MAC message preamble of 16 bits in length, a bit indicating a MAC message type of 2 bytes, a MAC message length of 1 byte, a MAC message body of various lengths, and a CRC And a 16-bit Message Check Sequence (MCS) field including a Cyclic Redundancy Check (MCS) field. The MCS message includes a CRC code appended in the MCS layer 33 for error detection at the receiving device. Here, the MAC message body field may use various lengths ranging from 1 bit to 254 bits according to the AVCL command. That is, when the AVCL command is transmitted from the transmitting device to the receiving device, the AVCL command is transmitted in the MAC body field of the MAC message of the transmitting device. According to an embodiment of the present invention, an echo request message is included in the MAC body field.

The MCS field may be calculated on all fields of the MAC message except for the preamble field, message type, message length, and message body field of the message. The long MAC message includes a null field.

The MAC message including the AVCL command is thus transmitted to the PHY layer 34 for transmission from the transmitting device to the receiving device. The exchange of information between devices is performed through each PHY layer.

28 to 30 are diagrams illustrating how a WHDI transmitting device is transmitted through a PHY layer to transmit a MAC message to a receiving device according to an embodiment of the present invention.

FIGS. 28 and 29 are diagrams illustrating a manner in which a WHDI source device transmits a MAC message including an echo request message to a sink device according to an embodiment of the present invention.

Referring to FIG. 28, when a MAC message is transmitted from a source device to a sink device, it can be transmitted through a DLPDU. That is, FIG. 28 corresponds to step S201 in which an echo request message is transmitted when the transmitting device is the source device and the receiving device is the sink device in FIG. 26 described above. In this case, the echo request message is included in a part of the MAC message including a plurality of messages. At least one MAC message of the source device is allocated to a plurality of frames, and the PHY layer 34 configures DLPDUs for each frame to be transmitted to the sink device.

The DLPDU includes a header section composed of a preamble, a CES, a basic header (BH) and an extension header (EH), an IQ section, and a section for transmitting a data / control bitstream. The Echo message included in the MAC message can be transmitted in the control bitstream in the data field for transmitting the data / control bitstream of the DLPDU.

9, the data / control bit stream, the test bit stream, the encoded audio bit stream, and the video quantization coefficient bit stream that have not undergone the encoding process are multiplexed into one bit stream in the bit stream MUX 73 Mixed. That is, the MAC message including the Echo Request message is included in the control bitstream, mixed with another data stream in the WHDI PHY layer, and encrypted by the Coarse Stream Encryptor 74. Thereafter, the signal is transmitted to the sink device through the transmission antenna through the signal transmission process described above with reference to FIG.

On the other hand, when the source device transmits a MAC message to the sink device via the downlink, the source device can transmit the MAC message through the data field of the DLPDU as well as the extended header (EH) period.

FIG. 29 is a diagram illustrating a form in which an echo request message included in a MAC message is included in an extension header (EH) when the source device transmits the echo request message to the sink device through the DLPDU.

The echo request message included in the extension header EH of the DLPDU is also transmitted to the sink device through mixing, encryption, modulation, and the like in the WHDI PHY together with the other bitstream as shown in FIG.

Next, the sink device that has received the echo request message from the source device via the DLPDU may transmit a response message to the received echo request message as a source message. At this time, the sink device transmits an echo report message to the source device through the ULCPDU on the uplink. First, the echo reply message is generated in the AVCL 32 of the sink device. The generated echo response message is included in the MAC layer 33 as a part of the MAC message, and is transmitted to the source device via the ULCPDU on the PHY layer 34 (S202).

The echo report message generated in the AVCL 32 may include a transmission device address, a receiving device address, an AVCL_Opcode, and an identifier. At this time, the host controller of the sink device selects an identifier of the same kind as the identifier included in the echo request message and includes it in the echo report message, so that the transmitting device can derive the RTT through message exchange with the receiving device. The echo report message generated in the AVCL 32 of the sink device is included in the MAC message as shown in FIG. 30 to configure the ULCPDU to be transmitted to the source device.

30 is a diagram showing a form in which an echo message included in a MAC message is transmitted through a ULCPDU from a sink device to a source device.

30 is a diagram illustrating a mode in which an echo report message included in a MAC message is transmitted to a source device through a ULCPDU in a sink device.

Referring to FIG. 30, the ULCPDU includes a preamble, a CES, an uplink control header (ULCH), and a data field for transmitting a data / control bitstream. The echo report message included in the MAC message may be included in a data field for transmitting the data / control bitstream of the ULCPDU and sent from the sink device to the active source device or to the passive source device. The transmission method based on the ULCPDU only concerns data not related to the A / V data. The echo report message is transmitted to the bitstream processor 81 without being mixed with the A / V data as shown in FIG. Lt; / RTI &gt; The data bitstream including the modulated echo report message is mapped to the OFDM symbol through the OFDM mapper 82 and is symbolized with the preamble added by the preamble MUX 85 via the IDFT transform 83 And is transmitted to the source device through the RF module 87. [

28 through 30 illustrate the case where the transmitting device is the source device and the receiving device is the sink device, the echo request message transmission step (S201) uses the DLPDU and the echo reporting message transmission step (S202) uses the ULCPDU It has been described in detail. On the contrary, in FIG. 26, when a transmitting device is a sink device and a receiving device is a source device, an echo request message transmitted from a sink device to a source device is composed of a ULCPDU and transmitted as shown in FIG. 30, Lt; RTI ID = 0.0 &gt; DLPDU &lt; / RTI &gt;

31 is a diagram illustrating a format of transmitting an echo request message from a WHDI source device to a sink device through a DLPDU according to another embodiment of the present invention.

As shown in Table 1 above, the Echo Request message or echo report message may include an identifier within any 32 bit range, such as a Timestamp. The identifier included in the echo report message is the same as the identifier included in the echo request message transmitted from the transmitting device.

The DLPDU may include a header section and a data transmission section 108 which are composed of a preamble 101, a basic header 105 and an extension header 106. The echo message 107 included in the extension header 106 may include, May be composed of bits indicating a transmission device address (Initiator_Addr) 1071, a receiving device address (Follower_Addr) 1072, an OPCODE 1073, and an identifier 1074. One or more devices included in the WHDI network need to be distinguished, and a bit indicating an address of the transmitting device and the receiving device is added to match the device address scheme. The 'OPCODE' field 1073 indicates the type of message, indicating that the AVCL command is an echo request message, and 1 byte is allocated using the 0x04 code. The identifier period may be any parameter within the 32-bit number limit. For example, the current sequence number and Timestamp of the transmission device may be used as the parameter, and 4 bytes are allocated to the identifier.

The echo report message includes a transmission device address section 1071, a reception device address section 1072, an OPCODE section 1075, and an identifier section 1074, similar to the echo request message. Here, the OPCODE field 1075 indicates that the AVCL command is an echo report message, and a 0 × 05 code is used and 1 byte is allocated. As described above, the identifier included in the echo report message uses the same parameters as those included in the echo request message.

Hereinafter, a case where a sequence number or a timestamp is included as an identifier in an echo request message according to an exemplary embodiment of the present invention will be described.

The transmitting device that is to send the message records its current sequence number and increments it by one when sending the data sequence and stores it again. At this time, if the sequence number increases to 255, it starts from 0 again. This is because the MAC messenger body interval allocated to the sequence in the MAC message has a length of 1 to 254 bytes as shown in FIG. The transmitting device can record and store the Timestamp value in 4 bytes together with the sequence number. The Timestamp value is a value obtained by recording the clock of the current transmitting device in msec.

The receiving device receiving the echo request message sends an echo report message to the transmitting device, allowing the transmitting device to calculate the RTT. To this end, the receiving device may copy the Timestamp when receiving the echo request message and store it as the Timestamp when transmitting the echo report message. Also, the sequence when receiving the echo request message is also copied and stored, and the same message is transmitted again to the transmitting device. Then, the transmitting device that has received the echo report message can extract the round trip time RTT by subtracting the Timestamp of the echo report message received at the current clock.

For example, if the sending device sends an Echo Request message with seq = 1 and Timestamp = 5, the receiving device can copy the Echo Request message and send it to the sending device with seq = 1, Timestamp = 5 echo report message. The transmitting device receives the echo report message, and when 100 is the current clock, it excludes Timestamp 5 from the current clock to obtain a round trip time of 95 ms. Also, if the only echo request message sent by seq = 1 is a 100% transmission success rate. That is, when only the Timestamp is selected as an identifier included in the echo request message, RTT can be obtained. In addition, when the sequence number is also added as an identifier, not only the RTT but also the transmission rate can be obtained.

32 is a flowchart illustrating a process of transmitting and receiving a wireless signal by adding an echo message in the WHDI according to an embodiment of the present invention. The sequence number and the timestamp are selected as parameters as the identifiers of the echo messages according to the embodiment described above.

Referring to FIG. 32, a transmitting device performs network measurement in order to transmit and receive wireless signals in the WHDI. First, the transmitting device to perform the measurement initializes its own variables to t = 1, n = 1 (S301). Where t represents the time of the timestamp, and n represents the sequence number. Then, the current time t is set to timestamp_t, and the number n of transmissions of the message is set to sequence_n to generate an echo request message (S302). Thereafter, when the host controller of the receiving device requests the WDHI transmitting device to transmit the message (S303), the transmitting device transmits an echo request message to the receiving device using the DLPDU or ULCPDU according to the routing rule (S304). The host controller of the receiving device copies the identifier parameter 108 of the echo request message to generate an echo report message (S305), and transmits the echo report message to the transmitting device again (S306). Then, the host controller of the transmitting device can obtain the RTT delay time from the result obtained by subtracting the time of the Timestamp from the current time, and stores the average value and the error range up to the present time (S307). The sequence is repeated until the sequence number n of the echo request message reaches Max Tests (S308). If the number of Max Tests is smaller than the Max Tests, the sequence number is incremented by one in step S302.

When the sequence number reaches the Max Tests count, the process from steps S302 to S309 ends. After the end, the host controller of the transmitting device calculates the transmission performance of the corresponding radio path (S310). For example, assuming that the average RTT delay is RTT Delay millisec, the size of data that can be transmitted at one time is MaxBytes bytes, and the transmission delay time between the sender and the receiver in the radio path is almost the same as the transmission delay time from the receiver to the sender , The available capacity for control data of the corresponding radio path can be expressed by Equation (3).

Max Throughput = Max Bytes x 8 x 1000 x 2 / RTT Delay (bps)

Specifically, the WDHI message transmission process will be described with reference to FIGS. 33 to 36. FIG.

33 is a diagram illustrating an exemplary process of exchanging echo messages between WHDI devices according to an embodiment of the present invention.

First, the active source device transmits an echo request message through the DLPDU to the sink device to measure the RTT (S401). For example, if the Timer at the time of sending the echo request message at the source device is 50 ms, the TimeStamp is recorded in the parameter TimeStamp = 5 included in the identifier period 1074 because the TimeStamp is 10 ms units. 32, the active source device inserts an echo request message 107 in a data transmission period or an extension header to transmit the DLPDU signal to the sink device. After receiving the echo request message, the sink device transmits the echo report message to the active source device via the ULCPDU after the Host Processing Time (i.e., the processing time of the host processor) corresponding to the response time of the host control unit (S402). The response message <Echo Report> is transmitted to the active source device through the ULCPDU transmitted in the Vertical Blanking Period of the video data signal transmission period originally transmitted from the active source device. When the active source device receives the echo report message, for example, if TimeStamp = 5, it multiplies 10ms, which is TimeUnit, and restores to 50ms. Using the value obtained by subtracting 50ms recovered from the current Timer value of 70ms, ). Therefore, from the time when the active source device first transmits the DLPDU including the echo request message to the sink device, the RTT required for receiving the ULCPDU including the echo report message from the sink device is extracted as 20 ms.

Next, FIG. 34 illustrates another embodiment of a process of exchanging echo messages between WHDI devices according to an embodiment of the present invention.

 Referring to FIG. 34, a sink device (or a passive source device) transmits a signal to an active source device through a ULCPDU, and transmits an echo request message through a ULCPDU (S501). The sink device records the current time of the timer in the echo report message as TimeStamp. For example, when the Timer is 15 ms and the TimeUnit is 10 ms, the parameter TimeStamp = 1 included in the identifier period 1074 is recorded. The echo report message is included in the ULCPDU data transmitted within the interval of the Vertical Blanking Period as described above. The active source device that received the echo report message transmits the Host Processing Time (that is, the processing time of the host processor) After roughing, the active sink device responds with an echo report message (S502). At this time, the echo report message is included in the section for transmitting the A / V data of the DLPDU or in the extension header. Since the parameter TimeStamp included in the identifier 1074 in the echo report message is equal to the TimeStamp of the echo request message, the sink device multiplies TimeStamp = 1 and TimeUnit 10ms to recover the original timer time of 10 ms. Therefore, an error of 5 ms occurs. If the current timer time is, for example, 37 ms, the RTT is 27 ms, which is the difference from the restored 10 ms.

In this way, the host controller of each device can easily predict the maximum transmission capacity for each radio path by using the echo request / report message. The host control unit can reduce a message loss due to throughput overflow by transmitting a message on the basis of the maximum transmission capacity for a predicted radio path and adjusting the intervals for transmitting the message based on the transmission capacity.

35 is a diagram showing an example of the WHDI network configuration.

Referring to FIG. 35, one active source device 110 can broadcast A / V data to the sink device 1 120 and the sink device 2 130 using DLPDU. The active source device 110 stores the device ID (6 bytes) of each device and uses the device ID when delivering the device list to another device.

On the other hand, the passive source device 140 can receive only the uplink signal from the sink device 1 or the sink device 2 and decode it into data. In addition, the message can be delivered to the active source device 110 using the ULCPDU. Therefore, the transmission path of the control message corresponds to the paths L1, L2, L3, L4 and L5 between the nodes of the active source device 110, the sink device 1 120, the sink device 2 130 and the passive source device 140 do.

Here, the sink device 1 120 may simultaneously transmit 200 20-byte vendor specific commands (AVCL) in the AVCL to the active source device 110 and the passive source device 140. In this case, if Max throughput measured in L1 path is 100kbps and MaxThroughput measured in L4 path is 20kbps, transmission interval is divided into active source device and sink device and transmitted. That is, a message is transmitted to the Queue_active source device at intervals of 20 bytes / 100 kbps = 1.5 ms, and the message is transmitted to the Queue_Sync device 1 at 20 byte / 20 kbps = 7.8 ms intervals, Can be transmitted. Thus, by separating the message transmission queues according to the maximum transmission amount of each path, the transmission time can be minimized and the success rate can be increased.

Generally, in one WHDI network, only active source devices transmit DLPDUs, and most WHDI source devices do not decode DLPDUs. Therefore, when the active source device 110 transmits a control message such as &quot; remote control path through &quot; to the passive source device 140, it is possible to transmit a control message such as a path &lt; L1, L4 & It must be transmitted over multiple radio paths including several radio paths.

Here, it is the type of the sender and receiver apparatus that determines the routing path. Referring to FIG. 35, when the active source device 110 transmits a control message, such as a remote control key, to the passive source device 140 wirelessly, the active source device 110 must pass the sink device 1 120 or the sink device 2 130. The latency is small and the message drop rate is low in order to satisfy the QoS requested by the user among the path <L1, L4> that the sink device 1 can pass and the path <L2, L3> You should choose this small path.

As described above, according to various embodiments of the present invention, when an echo message is used, it is possible not only to obtain an actual measurement value including the response time of the host control section, but also to make the response time in the same multi- Can be compared. Referring to FIG. 35, a signal can be transmitted from an active source device to a passive source device through two paths. That is, the first path including <L1, L4, L5> and the second path including <L2, L3, L5> are examined to compare the response time of the two paths. In this case, since both the first path and the second path include the L5 path, it is practically the same as that for comparing the paths <L1, L4> and <L2, L3>.

Therefore, by comparing RTT detection results according to the echo message exchange for the paths <L1, L4, L5>, and <L2, L3, L5>, it is possible to select a desired one of the sink device 1 and the sink device 2 as the intermediate way point of the passive source device have.

36 is a diagram illustrating another embodiment of a process of exchanging echo messages between WHDI devices according to an embodiment of the present invention. As shown in FIG. 36, the first path < L1, L4 , L5 >

The active source device records its TimeStamp in the DLPDU first, and transmits an echo request message to the DLPDU and transmits it to the sink device 1 concurrently with the A / V data (S601). In step S602, the sink device 1 having received the echo request message included in the DLPDU transmits the echo request message to the passive source device using the ULCPDU in the vertical blanking period because the destination address of the echo request message is the passive source device. The passive source device that received the echo request message creates an echo report message. Thereafter, the passive source device transmits an echo report message to the active source device in the vertical blanking interval period and transmits the echo report message to the ULCPDU (S603). Thereby, the active source device can calculate the RTT on the first path < L1, L4, L5 >.

The active source device extracts the average time of the RTT delay and the response rate of the echo report message by performing the path check once or more on the first path <L1, L4, L5> and the second path <L2, L3, L5> Thereby performing a more reliable inspection. The response rate of the echo report message can be expressed as N-t / N when the path check is performed N times and the response is N-t. The performance of the path can be quantified as shown in Equation (4).

M <path> = W _d × Delay + W _e × ErrorRate

Here, M <path> represents the performance of the path, Delay is the average of the RTT values, and ErrorRate is the value obtained by subtracting the response rate of the echo report message from 1. Where W _d and W _e are weights for Delay and ErrorRate, respectively. Delay dundamyeon performance with emphasis set to a value greater than the W _d W _e, and an emphasis on dundamyeon ErrorRate is set to be relatively larger value than the W _e W _d.

If the value of M <L1, L4, L5> is smaller than the value of M <L2, L3, L5> according to Equation (4) in the above embodiment, sink device 1 is set to the intermediate way point between the active source device and the passive source device And in the opposite case, the sink device 2 is set to the intermediate intermediate point. In this way, when there are N sink devices, selecting the path with the minimum M <Path> in each of the N paths increases the success rate of other types of message transmission and ensures a fast response time.

The terms used above may be replaced by others. For example, the device may be changed to a user device (or device), a station, etc., and the regulator may be an adjustment (or control) device, a tuning (or control) device, a tuning (or control) station, a coordinator ), A piconet coordinator (PNC), and the like. Alternatively, the AVCL command for transmitting / receiving data between the devices can be used in the same meaning as the AVCL message. That is, the echo request / report message can be viewed as an echo request / report command.

Although the technical features of the present invention have been described above with respect to the examples applied to the WVAN, the technical features of the present invention can be applied to a peer-to-peer communication system or other wireless network systems. Do.

The above-described embodiments are those in which the elements and features of the present invention are combined in a predetermined form. Each component or feature shall be considered optional unless otherwise expressly stated. Each component or feature may be implemented in a form that is not combined with other components or features. It is also possible to construct embodiments of the present invention by combining some of the elements and / or features. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments. It is also clear that claims which do not have an explicit citation in the claims can be combined to form an embodiment or included as a new claim by amendment after the application.

Embodiments in accordance with the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of hardware implementation, embodiments of the present invention may include one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs) programmable gate arrays, processors, controllers, microcontrollers, microprocessors, and the like.

In the case of an implementation by firmware or software, an embodiment of the present invention may be implemented in the form of a module, a procedure, a function, or the like which performs the functions or operations described above. The software code can be stored in a memory unit and driven by the processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various well-known means.

According to the present invention, a signaling process for establishing a connection between devices to transmit A / V data in a wireless network can be simplified.

It will be understood by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the embodiments described above are in all respects illustrative and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

1 is a diagram showing an example of a user device constituting a WVAN.

2 is a diagram showing an embodiment of a broadcast signal processing system including a broadcast signal receiver as an example of a transmitting device in the WHDI system.

3 is a diagram illustrating an example of a protocol layer structure implemented in a device in a WHDI system.

4 is a block diagram showing an example of a source device in the WHDI system.

5 is a diagram showing an example of a sink device in the WHDI system.

FIG. 6 shows a process of converting a general video signal including a vertical blanking period into an RF signal in a WHDI device in an A / V transmission / reception operation according to a temporal flow.

7 is a diagram illustrating an example of a DLPDU sequence when the WHDI PHY layer is in the Video Independent DLPDU mode.

8 is a diagram illustrating an example of a DLPDU sequence in a video dependent DLPDU mode in a WHDI PHY layer.

9 is a diagram showing an example of a PHY structure for transmitting a DLPDU in the WHDI system.

10 is a diagram showing the structure of an audio encoder in an example of a DLPDU PHY structure of a WHDI active source device.

11 is a diagram illustrating a structure of a video encoder in an example of a DLPDU PHY structure of a WHDI active source device.

12 is a diagram showing an example of block interleaving performed by the video encoder shown in FIG.

13 is a diagram showing quantization bits generated per video block in the DLPDU PHY structure of the WHDI active source device.

14 is a diagram illustrating a bitstream processor in an example of a DLPDU PHY structure of a WHDI active source device.

15 is a diagram illustrating a 16QAM array for transforming into a coefficient of IQ quadrature phase of a quantization factor stream in an example of a DLPDU PHY structure of a WHDI active source device.

16 is a diagram illustrating an example of a process of parsing an OFDM symbol in a symbol parser in an exemplary DLPDU PHY structure of a WHDI active source device.

17 is a diagram showing a quantization error data processing and encryption module in an example of a DLPDU PHY structure of a WHDI active source device.

18 is a diagram showing an example of the spectrum at the time of DLPHY RF transmission in the WHDI active source device.

19 is a diagram showing an example of ULIPDU transmission from a sink device to a source device in the WHDI system.

20 is a block diagram of a transmitting device that performs ULIPDU transmission to a receiving device in the WHDI system;

21 is a block diagram illustrating a bitstream processor of a transmitting device that performs ULIPDU transmission in a WHDI system;

22 is a diagram showing an example of a transmission spectrum in the case of 20 MHz in WHDI ULIPDU.

FIG. 23 is a diagram illustrating a Video Dependent Timing relationship between a DLPDU and a ULCPDU in a WHDI system. FIG. As described above, the PHY signal transmission in the WHDI uses the 5 GHz band.

24 is a block diagram showing the configuration of the ULCPDU transmitting device in the WHDI system;

25 is a block diagram showing the configuration of a bitstream processor in a ULCPDU transmitting device in a WHDI system.

26 is a diagram illustrating a process of transmitting and receiving an echo request message and an echo report message between the WHDI devices.

FIG. 27 is a diagram showing a configuration of a MAC message in the WHDI. FIG.

28 is a diagram illustrating an embodiment in which a MAC message including an echo request message is transmitted from a source device to a sink device through a DLPDU.

29 is a view showing another embodiment of a form in which a MAC message including an echo request message is transmitted from a source device to a sink device through a DLPDU.

30 is a diagram showing an embodiment of a mode in which a MAC message including an echo report message is transmitted from a sink device to a source device through a ULCPDU.

31 is a diagram illustrating a format of transmitting a MAC message including an echo request / report message from a source device to a sink device through a DLPDU according to another embodiment of the present invention.

32 is a flowchart illustrating a process of transmitting and receiving a wireless signal including an echo message between WHDI devices according to an embodiment of the present invention.

33 is a diagram illustrating an exemplary process of exchanging echo messages between devices of a WHDI according to an embodiment of the present invention.

34 is a diagram illustrating another embodiment of a process for exchanging echo messages between devices of a WHDI according to an embodiment of the present invention.

35 is a diagram showing an example of the WHDI network configuration.

FIG. 36 is a diagram illustrating another embodiment of a process for exchanging echo messages between devices of a WHDI according to an embodiment of the present invention. Referring to FIG.

Claims (22)

A message exchange method for measuring a round trip time between receiving devices in a transmitting device of a wireless network, An echo request message including a first identifier for identifying the transmitting device, a second identifier for identifying the receiving device, and a third identifier is generated in an AVC (Audio Video Control) layer, access control layer; Constructing a MAC message including a message preamble, a message type, and the echo request message in the MAC layer and transmitting the constructed MAC message to a physical layer; Transmitting to the receiving device a first physical layer data unit including at least one header, the MAC message, and audio / video (A / V) data at the physical layer; And Receiving a second physical layer data unit including an echo report message including the third identifier in response to the echo request message from the receiving device, Wherein the first physical layer data unit is a downlink physical layer data unit (DLPDU) and the second physical layer data unit is an uplink control physical layer data unit (ULCPDU) Characterized in that the message exchange method. The method according to claim 1, Wherein the MAC message is multiplexed with the A / V data at the physical layer. The method according to claim 1, Wherein the at least one header includes a Basic Header and an Extended Header, and the MAC message is included in the extension header. The method according to claim 1, Wherein the MAC message includes a CRC (Cyclic Redundancy Check) code added in the MAC layer for error detection in the receiving device. The method according to claim 1, Wherein the message type included in the MAC message indicates that the Echo Request message is an AVC command. delete delete delete delete delete A transmitting device in a wireless network, An AVC layer for generating an echo request message including a first identifier for identifying the transmitting device, a second identifier for identifying the receiving device, and a third identifier; A MAC layer for generating a MAC message including a message preamble, a message type, and the echo request message received from the AVC layer; And A first physical layer data unit including at least one header, at least one header, the MAC message, and audio / video (A / V) data and transmits the first physical layer data unit to the receiving device; And a physical layer for receiving a second physical layer data unit including an echo report message including a third identifier, Wherein the first physical layer data unit is a downlink physical layer data unit (DLPDU) and the second physical layer data unit is an uplink control physical layer data unit (ULCPDU). 12. The method of claim 11, And wherein the physical layer multiplexes the MAC message with the A / V data. 12. The method of claim 11, Wherein the at least one header comprises a Basic Header and an Extended Header, and the MAC message is included in the extension header. 12. The method of claim 11, Wherein the MAC layer adds a CRC code to the MAC message for error detection at the receiving device. 12. The method of claim 11, Wherein the message type included in the MAC message indicates that the echo request message is an AVC command. delete delete delete A transmitting device in a wireless network, A receiving unit for receiving a broadcast signal; A decoding unit decoding the broadcast signal received by the receiver; A display unit for displaying a content according to the broadcast signal decoded by the decoding unit; A first physical layer data unit including a MAC message including a broadcast signal, a message preamble, a message type, and an echo request message received by the receiver, and transmits the first physical layer data unit to the receiving device, A network control module for receiving and processing a second physical layer data unit including an echo report message in response to the second physical layer data unit; And Wherein the transmitting device measures the round trip time between the receiving devices through the echo request / report message exchanged through the network control module, or stores the received broadcasting signals in the local storage device, And a control unit for controlling the reproduction of the content, Wherein the first physical layer data unit is a downlink physical layer data unit (DLPDU) and the second physical layer data unit is an uplink control physical layer data unit (ULCPDU). Transmitting device. 20. The method of claim 19, Wherein the echo request message comprises a first identifier for identifying the transmitting device, a second identifier for identifying the receiving device, and a third identifier. delete delete

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