# Patent

## Title
Reception apparatus and method for demodulating signal in wireless AV system

## Abstract

The present specification relates to a reception apparatus and method for demodulating a signal in a wireless AV system. The reception apparatus estimates a transmission signal on the basis of an MMSE weight matrix. The reception apparatus divides the estimated transmission signal for respective reception antennas and performs an IFFT. The reception apparatus estimates and compensates for phase noise for the respective reception antennas on the basis of the signal for which the IFFT has been performed. The reception apparatus demodulates the estimated and compensated signal for respective streams.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is the National Stage filing under 35 U.S.C. 371 of International Application No. PCT/KR2020/001497, filed on Jan. 31, 2020, the contents of which is hereby incorporated by reference herein in its entirety.
BACKGROUND OF THE DISCLOSURE
Field of the Disclosure
The present disclosure relates to a wireless audio/video (AV) system, and more particularly, to a receiving apparatus and method for demodulating a signal in a wireless AV system.
Related Art
Recently, there is a growing demand for high-resolution and high-quality pictures such as a high definition (HD) picture and an ultra-high definition (UHD) picture in various fields. The higher the resolution and quality of picture data, the greater the amount of information of bits to be transmitted relative to the existing picture data. Therefore, transmission cost may increase when the picture data is transmitted using a medium such as the existing wired/wireless broadband line.
Meanwhile, the institute of electrical and electronics engineers (IEEE) 802.11ad standard is a high-speed wireless communication standard which operates in a band of at least 60 GHz. A signal reachable range is about 10 meters, but a throughput of at least 6 Gbps may be supported. The IEEE 802.11ad standard provides a beamforming training process for antenna beam alignment. IEEE 802.11ay is a next-generation standard which is under development for the purpose of a throughput of at least 20 Gbps based on the IEEE 802.11ad.
Multiple access and communication between a plurality of unspecified devices are premised in case of the existing standard such as a series of IEEE 802.11ad or ay. Therefore, a data format or frame format used by a medium access control (MAC) layer or physical layer of the series of IEEE 802.11ad or ay includes a plurality of control information fields for controlling and managing resources and operations of a plurality of devices. However, in an application of a wireless AV system to which the present disclosure belongs, wireless communication in a situation where peer devices are specified is premised in most cases (e.g., communication between a wireless set-top box and a wireless TV).
In a wireless AV system, a data transmitting device and/or data receiving device may be equipped with multiple antennas. Most particularly, in case the data transmitting device and/or data receiving device use(s) a polarization antenna, orthogonality among the antennas may be ensured. When performing multiple input multiple output (MIMO) transmission through a polarization antenna, since inter-stream interference (ISI) may be removed, optimal MIMO performance can be ensured.
SUMMARY OF THE DISCLOSURE
Technical Objects
The present specification proposes a receiving apparatus and method for demodulating a signal in a wireless AV system.
Technical Solutions
This embodiment proposes a receiving apparatus and method for demodulating a radio AV signal.
It is a flowchart illustrating a procedure for demodulating a transmission signal in a receiving device.
This embodiment proposes a method for estimating and compensating for phase noise in a multi-receiving antenna environment in wireless AV (Audio/Video) transmission. In particular, this embodiment proposes a signal demodulation method in which a transmission signal is decomposed for each reception antenna to enable parallel operation. Accordingly, performance degradation due to phase noise may be prevented and complexity and latency may be minimized.
This embodiment will be described from the viewpoint of the receiving device. The receiving device and the transmitting device may be wireless devices supporting mmWave wireless communication. That is, this embodiment describes a method of effectively demodulating a transmitted signal while minimizing performance degradation due to phase noise in a 60 GHz or higher mmWave communication system.
The receiving device estimates a transmission signal based on a Minimum Mean Square Error (MMSE) weight matrix.
The receiving device decomposes the estimated transmission signal for each reception antenna and performs Inverse Fast Fourier Transform (IFFT).
The receiving device estimates and compensates for phase noise for each receiving antenna based on the signal on which the IFFT has been performed.
The receiving device demodulates the estimated and compensated signals for each stream.
EFFECTS OF THE DISCLOSURE
According to the proposed embodiment, there is an effect that demodulation performance of a receiving device supporting mmWave wireless communication can be improved by estimating and compensating for the decorrelation phase noise between the receiving antennas with low complexity.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a wireless display system according to an embodiment.
FIG. 2 is a block diagram of a wireless data transceiving system according to an embodiment.
FIG. 3 is a conceptual diagram illustrating a case where a wireless data transceiving system is implemented with an IEEE 802.11 series communication protocol according to an embodiment.
FIG. 4 is a diagram for describing a configuration of a beacon interval according to an embodiment.
FIG. 5 is a diagram briefly illustrating a configuration of a physical protocol data unit (PPDU) frame according to an embodiment.
FIG. 6 shows multiple antennas having one RF chain being configured of a dual polarization array according to an embodiment of the present specification.
FIG. 7 shows a beamforming training process according to an embodiment of the present specification.
FIG. 8 is a graph illustrating a relationship between a frequency offset and a Power Spectral Density (PSD).
FIG. 9 shows the SC mode frame structure of 802.11ay.
FIG. 10 shows a block diagram of a receiver of mmWave wireless communication.
FIG. 11 is a graph comparing packet error rates for phase noise compensation.
FIG. 12 is a graph comparing packet error rates for phase noise compensation.
FIG. 13 is a graph comparing packet error rates for phase noise compensation.
FIG. 14 is a flowchart illustrating a procedure for demodulating a transmission signal in the receiving device according to the present embodiment.
FIG. 15 is a block diagram illustrating a receiving device for demodulating a transmission signal according to the present embodiment.



DESCRIPTION OF EXEMPLARY EMBODIMENTS
Hereinafter, embodiments of a wireless data transmitting device and method and a wireless data receiving device and method are described in detail according to the present disclosure, but the present disclosure is not limited thereto. Features of the present disclosure are described by the illustrated embodiments. However, functions and structures identical or equivalent to the embodiments described in the present specification are included within the spirit and scope of the present disclosure, and may also be achieved by other intended embodiments. Throughout the present specification, like reference numbers indicate like parts or features. Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.
Recently, a design of a display device such as a TV is becoming more important, and a display panel is gradually becoming thinner with the development of a display panel technology such as OLED. However, there is a limitation in producing and designing a thinner display panel due to a basic thickness of a driving circuit which drives the display panel. Therefore, there is a growing attention for a technique in which the remaining components other than inevitable components to be physically and electrically coupled with the display panel are separated from the display panel and provided in a separate device (hereinafter, referred to as a mainframe device). In this case, the mainframe device and the display device may be configured to mutually exchange a video signal and an audio signal, based on wireless communication. The present disclosure relates to a wireless AV system or wireless display system of which a mainframe device and a display device are physically and/or electrically independent as described above and which mutually reproduces media, based on wireless communication.
FIG. 1 is a block diagram of a wireless AV system according to an embodiment.
Referring to FIG. 1, a wireless AV system 10 may include a mainframe device 100, a display device 200, and a remote control device 300.
The mainframe device 100 may perform an operation of receiving a wired/wireless-type external signal related to audios, videos, pictures, images, multimedia, or at least one combination thereof, generating a data stream or bit stream by processing the received external signal in various manners, and transmitting it to the display device 200 through a wireless interface.
In order to perform such an operation, the mainframe device 100 may include an external signal receiving unit 110, an external device interface unit 115, a storage unit 120, a mainframe control unit 130, a wireless communication circuit 140, and a power supply unit 150.
The external signal receiving unit 110 may include a tuner 111, a demodulation unit 112, and a network interface unit 113.
The tuner 111 receives a wired/wireless-type external signal related to audios, videos, pictures, images, multimedia, or at least one combination thereof. For example, the tuner 111 may select a specific broadcast channel according to a channel selection command and receive a broadcast signal for the selected specific broadcast channel.
The demodulation unit 112 may separate the received external signal into a video signal, an image signal, a picture signal, an audio signal, a data signal related to a broadcast program, or the like, and may restore the separated video signal, image signal, picture signal, audio signal, data signal related to the broadcast program, or the like into a format which can be output.
The external device interface unit 115 may receive an application or an application list in an adjacent external device and transmit it to the mainframe control unit 130 or the storage unit 120.
The external device interface unit 115 may provide a connection path between the mainframe device 100 and the external device. The external device interface unit 115 may receive one or more of audios, videos, pictures, images, multimedia, and at least one combination thereof output from the external device coupled in a wireless or wired manner to the mainframe device 100, and may transfer it to the mainframe control unit 130. The external device interface unit 115 may include a plurality of external input terminals. The plurality of external input terminals may include an RGB terminal, one or more high definition multimedia interface (HDMI) terminals, and a component terminal.
The external device that can be coupled with the external device interface unit 115 may be any one of a set-top box, a Blu-ray player, a DVD player, a game device, a sound bar, a smartphone, a PC, a USB memory, and a home theater, but this is for exemplary purposes only.
The network interface unit 113 may provide an interface for coupling the mainframe device 100 to a wired/wireless network including an Internet network. The network interface unit 113 may transmit or receive data with another user or another electronic device through an accessed network or another network linked to the accessed network.
In addition, part of content data stored in the mainframe device 100 may be transmitted to a selected user or a selected electronic device among the pre-stored other users or other electronic devices.
The network interface unit 113 may access a predetermined webpage through the accessed network or another network linked to the accessed network. That is, data can be transmitted or received with a corresponding server by accessing the predetermined webpage through the network.
In addition, the network interface unit 113 may receive content or data provided by a content provider or a network operator. That is, the network interface unit 113 may receive content such as movies, advertisements, games, VODs, broadcast signals, or the like provided from the content provider or the network operator through the network, and information related to the content.
In addition, the network interface unit 113 may receive update information and update files of firmware provided by the network operator, and may transmit data to the Internet or content provider or the network operator.
The network interface unit 113 may select and receive a desired application among applications open to the public through the network.
The storage unit 120 may store a program for processing and controlling each signal in the mainframe control unit 130, and may store signal-processed video, audio, or data signals.
In addition, the storage unit 120 may perform a function for temporarily storing a picture, audio, or data signal input from the external device interface unit 115 or the network interface unit 113, and may store information related to a predetermined image through a channel memory function.
The storage unit 120 may store an application or an application list input from the external device interface unit 115 or the network interface unit 113.
The mainframe control unit 130 may control the mainframe device 100 by a user command or internal program input through the remote control device 300, and may access the network to download an application desired by a user or an application list into the mainframe device 100.
The mainframe control unit 130 may allow channel information or the like selected by the user to be output through the display device 200 or an audio output unit 250 together with the processed picture or audio signal.
In addition, the mainframe control unit 130 may allow a picture signal or an audio signal, provided from an external device, for example, a camera or a camcorder, input through the external device interface unit 115, to be output through the display device 200 or the audio output unit 250, according to an external device picture playback command received through the remote control device 300.
In addition, the mainframe control unit 130 may provide control to reproduce content stored in the storage unit 120, broadcast content received, and external input content which is input from the outside. The content may have various formats such as a broadcast picture, an external input picture, an audio file, a still picture, an accessed web screen, a text file, or the like.
The mainframe control unit 130 may perform an operation of decoding data or the like related to a video, image, picture, audio, and broadcast program input through the demodulation unit 112, the external device interface unit 115, or the storage unit 120, encoding again the decoded data in accordance with an encoding/decoding scheme supported by the display device 200, generating a data stream or a bit stream by processing data through various picture/audio processing schemes such as compression or encoding so that the encoded data is transmitted through a wireless channel, and transmitting the generated data stream or bit stream to the display device 200 through the wireless communication circuit 140. According to an embodiment, the mainframe control unit 130 may transmit the decoded data again to the display device 200 directly through the wireless communication circuit 140 by bypassing the decoded data without having to encode it in accordance with the encoding/decoding scheme supported by the display device 200.
In addition, the mainframe control unit 130 may be configured to implement functions, procedures, and/or methods of a processor 1130 of a wireless data transmitting device 1100 described in each embodiment of the present specification. Layers of a wireless interface protocol may be implemented in the processor 1130.
The wireless communication circuit 140 is operatively coupled with the mainframe control unit 130 to receive a data stream or a bit stream from the mainframe control unit 130, generates a wireless stream by encoding and/or modulating the data stream or the bit stream so that it can be transmitted through a wireless channel, and transmits the wireless stream to the display device 200. The wireless communication circuit 140 establishes a wireless link, and the mainframe device 100 and the display device 200 are coupled by means of the wireless link. The wireless communication circuit 140 may be implemented based on various wireless communication schemes, for example, short-range wireless communication such as WI-FI, Bluetooth, NFC, and RFID, or a mobile communication network (e.g., 3G, 4G, 5G cellular network, etc.). For example, the wireless communication circuit 140 may perform communication using a communication protocol such as the IEEE 802.11 series standard.
The power supply unit 150 supplies power to the external signal receiving unit 110, the external device interface unit 115, the storage unit 120, the mainframe control unit 130, and the wireless communication circuit 140. A scheme in which the power supply unit 150 receives power from the outside may include a terminal scheme and a wireless scheme. When the power supply unit 150 receives power in a wireless manner, the power supply unit 150 may include a separate component for wirelessly receiving power. For example, the power supply unit 150 may include a power pick-up unit configured to receive wireless power by magnetic coupling with an external wireless power transmitting device, and a separate communication and control unit configured to perform communication with the wireless power transmitting device and control transmission and reception of wireless power.
The wireless communication circuit 140 may also be wirelessly coupled with the remote control device 300 to transfer a signal input by the user to the mainframe control unit 130 or transfer a signal from the mainframe control unit 130 to the user. For example, according to various communication schemes such as Bluetooth, ultra wideband (WB), Zigbee, a radio frequency (RF) communication scheme, or an infra-red (IR) communication scheme, the wireless communication circuit 140 may receive from the remote control device 300 a control signal such as power on/off, screen setting, or the like of the mainframe device 100, or may transmit the control signal from the mainframe control unit 130 to the remote control device 300.
In addition, the wireless communication circuit 140 may transfer to the mainframe control unit 130 a control signal input from a local key (not shown) such as a power key, a volume key, a set value, or the like.
Next, the display device 200 may perform a display or audio output operation after processing a wireless stream received from the mainframe device 100 through a wireless interface according to a reverse process of signal processing performed by the mainframe device 100. In order to perform such an operation, the display device 200 may include a wireless communication circuit 210, a user input interface unit 220, a panel control unit 230, a display unit 240, an audio output unit 250, and a power supply unit 260.
The wireless communication circuit 210 is coupled with the wireless communication circuit 140 of the mainframe device 100 through a wireless link to perform wireless communication with the wireless communication circuit 130 of the mainframe device 100. Specifically, the wireless communication circuit 210 receives a wireless stream from the wireless communication circuit 140 of the mainframe device 100, demodulates the wireless stream, and transmits the demodulated wireless stream to the panel controller 230. The wireless communication circuit 210 may be implemented based on various wireless communication schemes, for example, short-range wireless communication such as WI-FI, Bluetooth, NFC, and RFID, or a mobile communication network (e.g., 3G, 4G, 5G cellular network, etc.). For example, the wireless communication circuit 210 may perform communication using a communication protocol such as the IEEE 802.11 series standard, e.g., IEEE 802.11ay.
The panel control unit 230 decodes a signal demodulated by the wireless communication circuit 210 to restore a bit stream or a data stream. In this case, when the bit stream or data stream is compressed, the panel controller 230 performs an operation of decompressing or restoring the bit stream or data stream, and then outputs signals such as a video signal, an image signal, a picture signal, an audio signal, and a data signal related to a broadcast program. The signals may be sent to the display unit 240, the audio output unit 250, and the user input interface unit 220.
The video signal, the picture signal, the image signal, or the like may be input to the display unit 240 and may be displayed as a picture corresponding to the picture signal. In addition, a picture signal processed by the panel control unit 230 may be transmitted again to the mainframe device 100 through the wireless communication circuit 210, and may be input to an external output device through the external device interface unit 115 of the mainframe device 100.
An audio signal processed by the panel controller 230 may be output to the audio output unit 250. In addition, the audio signal processed by the panel control unit 230 may be transmitted again to the mainframe device 100 through the wireless communication circuit 210, and may be input to the external output device through the external device interface unit 115 of the mainframe device 100.
Meanwhile, the panel control unit 230 may control the display unit 240 to display a picture, for example, may provide control such that a broadcast picture input through the tuner 111, an external input picture input through the external device interface unit 115, a picture input through the network interface unit, or a picture stored in the storage unit 120 is displayed on the display unit 240. In this case, the picture displayed on the display unit 240 may be a still picture or a moving picture, and may be a 2D picture or a 3D picture.
The panel controller 230 may be configured to implement functions, procedures, and/or methods of a processor 1230 of a wireless data receiving device 1200 described in each embodiment of the present specification. In addition, the processor 1230 may be configured to implement functions, procedures, and/or methods of the wireless data receiving device 1200 described in each embodiment of the present specification.
The user input interface 220 may transfer a signal input by the user to the panel control unit 230 or transfer a signal from the panel control unit 230 to the user. For example, according to various communication schemes such as Bluetooth, ultra wideband (WB), Zigbee, a radio frequency (RF) communication scheme, or an infra-red (IR) communication scheme, the user input interface unit 220 may receive from the remote control device 300 a control signal such as power on/off, screen setting, or the like of the display device 200, or may transmit the control signal from the panel control unit 230 to the remote control device 300.
In addition, the user input interface unit 220 may transfer to the panel control unit 230 a control signal input from a local key (not shown) such as a power key, a volume key, a set value, or the like.
The power supply unit 150 supplies power to the wireless communication circuit 210, the user unit interface unit 220, the panel control unit 230, the display unit 240, and the audio output unit 250. A scheme in which the power supply unit 260 receives power from the outside may include a terminal scheme and a wireless scheme. When the power supply unit 260 receives power in a wireless manner, the power supply unit 260 may include a separate component for wirelessly receiving power. For example, the power supply unit 260 may include a power pick-up unit configured to receive wireless power by magnetic coupling with an external wireless power transmitting device, and a separate communication and control unit configured to perform communication with the wireless power transmitting device and control transmission and reception of wireless power.
The remote control device 300 performs an operation in which the mainframe device 100 and/or the display device 200 remotely control power on/off, channel selection, screen setting, or the like, and may be referred to as a remote controller.
Meanwhile, since the mainframe device 100 and display device 200 of FIG. 1 are only one embodiment of the present specification, some of components illustrated herein may be integrated, added, or omitted according to specifications of the mainframe device 100 and display device 200 actually implemented. That is, if necessary, two or more components may be combined into one component, or one component may be subdivided into two or more components. In addition, a function performed in each block is for explaining the embodiments of the present disclosure, and a specific operation or device does not limit the scope of the present disclosure.
According to another embodiment of the present disclosure, unlike in FIG. 1, the mainframe device 100 does not include the tuner 111 and the demodulation unit 112, and may receive a picture through the network interface unit 113 or the external device interface unit 115 to reproduce the picture.
For example, the mainframe device 100 may be implemented by being divided into a picture processing device such as a set-top box or the like for receiving a broadcast signal or content according to various network services and a content reproducing device for reproducing content input from the picture processing device.
In this case, a method of operating the wireless AV system 10 according to an embodiment of the present disclosure to be described below may be performed by not only the mainframe device 100 and the display device 200 as described with reference to FIG. 1 but also any one of a picture processing device such as the separate set-top box or the like and a content reproducing device having the audio output unit 250.
In terms of system input/output, the mainframe device 100 may be referred to as a wireless source device which provides a source wirelessly, and the display device 200 may be referred to as a wireless sink device which receives the source wirelessly. The wireless source device and the wireless sink device may implement wireless display (WD) communication techniques compatible with standards such as wireless HD, wireless home digital interface (WHDI), WiGig, wireless USB, and Wi-Fi display (WFD) (also known as Miracast).
In terms of an application, the mainframe device 100 may be integrated in a form of constituting part of a wireless set-top box, a wireless gaming console, a wireless digital video disk (DVD) player, and a wireless writer. In this case, the mainframe device 100 may be provided in a form of a wireless communication module or chip. In addition, the display device 200 may be integrated in a form of constituting part of a user device or electronic device (e.g., a wireless TV, a wireless monitor, a wireless projector, a wireless printer, a wireless vehicle dashboard display, a wearable device, an augmented reality (AR) headset, a virtual reality (VR) headset, etc.) having a display panel for displaying an image or a video. In this case, the display device 200 may be provided in a form of a wireless communication module or chip.
The mainframe device 100 and the display device 200 may be integrated in a form of constituting part of a mobile device. For example, the mainframe device 100 and the display device 200 may be integrated into a mobile terminal including smartphones, smart pads, or tablets, or other types of wireless communication devices, portable computers having wireless communication cards, a personal digital assistant (PDA), a portable media player, a digital image capturing device such as a camera or a camcorder, or other flash memory devices having wireless communication capabilities. In this case, the mainframe device 100 and the display device 200 may be provided in a form of a wireless communication module or chip.
A smartphone user may stream or mirror a video or audio output by a user's smartphone, tablet, or other computer devices to another device such as a television or projector capable of providing a higher resolution display or other enhanced user experiences.
As described above, the mainframe device 100 may perform an operation of receiving a wired/wireless-type external signal related to audios, videos, pictures, images, multimedia, or at least one combination thereof, generating a data stream or bit stream by processing the received external signal in various manners, and transmitting it to the display device 200 through a wireless interface.
Hereinafter, the picture/video/audio data transmitted through the wireless interface is collectively referred to as wireless data. That is, the mainframe device 100 may communicate wirelessly with the display device 200 and transmit wireless data. Therefore, in terms of a wireless data transceiving system 1000, the mainframe device 100 may be referred to as the wireless data transmitting device 1100, and the display device 200 may be referred to as the wireless data receiving device 1200. Hereinafter, the present disclosure will be described in greater detail in terms of the wireless data transceiving system 1000. First, a detailed block diagram of the wireless data transceiving system 1000 is disclosed.
FIG. 2 is a block diagram of a wireless data transceiving system according to an embodiment.
Referring to FIG. 2, the wireless data transceiving system 1000 refers to a system for transmitting and receiving a data stream wirelessly, and includes the wireless data transmitting device 1100 and at least one wireless data receiving device 1200. The wireless data transmitting device 1100 is communicatively coupled with the at least one wireless data receiving device 1200.
In terms of a wireless communication system (i.e., WLAN, WiFi), the wireless data transmitting device 1100 may be referred to as an AP or a personal basic service set control point (PCP) station, and the wireless data receiving device 1200 may be referred to as an STA or a non-PCP station.
In terms of input/output of a data stream, the wireless data transmitting device 1100 may be referred to as a wireless source device which provides a source wirelessly, and the wireless data receiving device 1200 may be referred to as a wireless sink device which receives the source wirelessly. The wireless source device and the wireless sink device may implement wireless display (WD) communication techniques compatible with standards such as wireless HD, wireless home digital interface (WHDI), WiGig, wireless USB, and Wi-Fi Display (WFD) (also known as Miracast).
In terms of an application, the wireless data transmitting device 1100 may be integrated in a form of constituting part of a wireless set-top box, a wireless gaming console, a wireless digital video disk (DVD) player, and a wireless writer. In this case, the wireless data transmitting device 1100 may be provided in a form of a wireless communication module or chip. In addition, the wireless data receiving device 1200 may be integrated in a form of constituting part of a user device or electronic device (e.g., a wireless TV, a wireless monitor, a wireless projector, a wireless printer, a wireless vehicle dashboard display, a wearable device, an augmented reality (AR) headset, a virtual reality (VR) headset, etc.) having a display panel for displaying an image or a video. In this case, the wireless data receiving device 1200 may be provided in a form of a wireless communication module or chip.
The wireless data transmitting device 1100 and the wireless data receiving device 1200 may be integrated in a form of constituting part of a mobile device. For example, the wireless data transmitting device 1100 and the wireless data receiving device 1200 may be integrated into a mobile terminal including smartphones, smart pads, or tablets, or other types of wireless communication devices, portable computers having wireless communication cards, a personal digital assistant (PDA), a portable media player, a digital image capturing device such as a camera or a camcorder, or other flash memory devices having wireless communication capabilities. In this case, the wireless data transmitting device 1100 and the wireless data receiving device 1200 may be provided in a form of a wireless communication module or chip.
A smartphone user may stream or mirror a video or audio output by a user's smartphone, tablet, or other computer devices to another device such as a television or projector capable of providing a higher resolution display or other enhanced user experiences.
In an aspect, data may include audios, videos, pictures, images, and multimedia, or may be constructed of at least one combination thereof.
In another aspect, the data may include a bit stream of an audio-compressed format, a bit stream of a video-compressed format, a bit stream of a picture-compressed format, and a bit stream of a multimedia-compressed format, or may include at least one combination thereof. In this case, the wireless data transceiving system 1000 may also be referred to as a wireless compressed data stream transceiving system. In addition, the wireless compressed data stream transceiving system 1000 may further include a functional or physical unit for compressing data.
Regarding a detailed structure of each device, the wireless data transmitting device 1100 includes a memory 1120, a processor 1130, a communication circuit 1140, and a plurality of antennas 1150-1, 1150-2, . . . , 1150-NTx, and the wireless data receiving device 1200 includes a communication circuit 1210, a memory 1220, a processor 1230, and a plurality of antennas 1250-1, 1250-2, . . . , 1250-NRx.
The memories 1120 and 1220 are operatively coupled to the processors 1130 and 1230, and store a variety of information for operating the processors 1130 and 1230. The memories 1120 and 1220 may include a read-only memory (ROM), a random access memory (RAM), a flash memory, a memory card, a storage medium, and/or other equivalent storage devices.
The processor 1130 may be configured to implement functions, procedures, and/or methods of the wireless data transmitting device 1100 described in each embodiment of the present specification. In addition, the processor 1230 may be configured to implement functions, procedures, and/or methods of the wireless data receiving device 1200 described in each embodiment of the present specification. Layers of the wireless interface protocol may be implemented in the processors 1130 and 1230.
In terms of the display system of FIG. 1, the processor 1130 may be configured to perform a function of the mainframe control unit 130. For example, the processor 1130 may perform an operation of decoding data or the like related to a video, image, picture, audio, and broadcast program input through the demodulation unit 112, the external device interface unit 115, or the storage unit 120, generating a data stream or a bit stream by processing data through various picture/audio processing schemes such as compression or encoding so that the decoded data is transmitted through a wireless channel, and transmitting the generated data stream or bit stream to the display device 200 through the communication circuit 1140.
The processors 1130 and 1230 may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, and/or data processors.
When the embodiment is implemented in software, the techniques explained in the present specification may be implemented with a module (i.e., procedure, function, etc.) for performing the functions explained in the present specification. The module may be stored in the memories 1120 and 1220 and may be performed by the processors 1130 and 2310. The memories 1120 and 1220 may be implemented inside the processors 1130 and 2310. Alternatively, the memories 1120 and 1220 may be implemented outside the processor 2310, and may be coupled to the processors 1130 and 1230 in a communicable manner by using various well-known means.
The communication circuits 1140 and 1210 may include a baseband circuit for processing a radio frequency signal. The communication circuits 1140 and 1210 are operatively coupled to the processors 1130 and 1230, and transmit and/or receive data wirelessly. A communication channel constituted by the communication circuits 1140 and 1210 may be a network communication channel. In this case, the communication circuits 1140 and 1210 may establish a tunneled direct link setup (TDLS) which is tunneled to avoid or reduce network congestion. The Wi-Fi direct and the TDLS are used to set up relatively short-range communication sessions. A communication channel constituting a radio link 11 may be a communication channel of a relatively short range, or may be a communication channel implemented using a physical channel structure such as Wi-Fi, Bluetooth, or the like which uses various frequencies such as 2.4 GHz, 3.6 GHz, 5 GHz, 60 GHz, or ultra wide band (UWB).
Although techniques disclosed in the present specification may be primarily described in association with a communication protocol such as an IEEE 802.11 series standard, aspects of these techniques may also be compatible with other communication protocols. For example, the communication circuits 1140 and 1210 may be implemented based on various wireless communication schemes, such as short-range wireless communication, e.g., WI-FI, Bluetooth, NFC, and RFID, or a mobile communication network (e.g., 3G, 4G, 5G cellular network, etc.), or may perform communication by using a communication protocol such as the IEEE 802.11 series standard. By way of example and without limitation, wireless communication between the communication circuits 1140 and 1210 may use orthogonal frequency division multiplexing (OFDM) techniques. It is also possible to use various other wireless communication techniques including, but not limited to, time division multiple access (TDMA), frequency division multiple access (FDMA), code division multiple access (CDMA), or any combination of OFDM, FDMA, TDMA and/or CDMA.
FIG. 3 is a conceptual diagram illustrating a case where a wireless data transceiving system is implemented with an IEEE 802.11 series communication protocol according to an embodiment.
Referring to FIG. 3, a wireless data transceiving system 20 of FIG. 3(A) may include one or more basic service sets (hereinafter, referred to as ‘BSSs’) 21 and 25. The BSS is a set of access points (hereinafter, APs) and stations (hereinafter, STAs) that can successfully synchronize and communicate with each other and is not a concept indicating a specific region.
For example, the first BSS 21 may include a first AP 22 and one first STA 21-1. The second BSS 25 may include a second AP 26 and one or more STAs 25-1 and 25-2. Herein, the first AP 22 may correspond to the communication circuit 1140 of FIG. 2, and the one or more STAs 25-1 and 25-2 may correspond to the communication circuit 1210 of FIG. 2.
The infrastructure BSSs 21 and 25 may include at least one STA, the APs 22 and 26 providing a distribution service, and a distribution system 27 for connecting the plurality of APs.
The distribution system 27 may connect the plurality of BSSs 22 and 26 to implement an extended service set (hereinafter, ‘ESS’) 28. The ESS 28 may be used as a term indicating one network to which the one or more APs 22 and 26 are connected through the distribution system 27. At least one AP included in one ESS 28 may have the same service set identification (hereinafter, SSID).
A portal 29 may serve as a bridge for connecting the WLAN network (IEEE 802.11) with another network (e.g., 802.X).
In a WLAN having a structure as shown in FIG. 3(A), a network between the APs 22 and 26 and a network between the APs 22 and 26 and the STAs 21-1, 25-1, and 25-2 may be implemented.
Meanwhile, a wireless data transceiving system 30 of FIG. 3(B) may perform communication by setting a network between STAs without the APs 22 and 26, unlike FIG. 3(A). A network that performs communication by setting a network even between STAs without the APs 22 and 26 is defined to an ad-hoc network or an independent basic service set (hereinafter, ‘BSS’).
Referring to FIG. 3(B), the wireless data transceiving system 30 is a BSS that operates in an Ad-Hoc mode, i.e., IBSS. Since the IBSS does not include an AP, there is no centralized management entity. Therefore, in the wireless data transceiving system 30, STAs 31-1, 31-2, 31-3, 32-4, and 32-5 are managed in a distributed manner. Herein, the STAs 31-1, 31-2, 31-3, 32-4, and 32-5 may correspond to the communication circuit 1140 or communication circuit 1210 of FIG. 2.
All of the STAs 31-1, 31-2, 31-3, 32-4, and 32-5 of the IBSS may be configured with mobile STAs, and access to a distributed system is not allowed. All STAs of the IBSS form a self-contained network.
The STA described in the present specification is a random function medium including a medium access control (hereinafter, MAC) following a standard of the institute of electrical and electronics engineers (IEEE) 802.11 standard and a physical layer interface for a wireless medium and may broadly be used as a meaning including both an AP and a non-AP station (STA).
The STA described in the present specification may also be referred to as various names such as a mobile terminal, a wireless device, a wireless transmit/receive unit (WTRU), a user equipment (UE), a mobile station (MS), a mobile subscriber unit, or simply a user.
FIG. 4 is a diagram for describing a configuration of a beacon interval according to an embodiment.
Referring to FIG. 4, in an enhanced directional multi-gigabit (EDMG) system, a time of media may be divided into beacon intervals. Sub-periods within the beacon interval may be referred to as an access period. Different access periods within one beacon interval may have different access rules. Information on the access period may be transmitted by an AP or a personal basic service set control point (PCP) to a non-AP STA or a non-PCP.
One beacon interval may include one beacon header interval (BHI) and one data transfer interval (DTI). As shown in FIG. 4, the BHI may include a beacon transmission interval (BTI), an association beamforming training (A-BFT), and an announcement transmission interval (ATI).
The BTI refers to a period in which one or more EDMG beacon frames can be transmitted. The A-BFT refers to a period in which beamforming training is performed by an STA which has transmitted the EDMG beacon frame during a preceding BTI. The ATI refers to a management access period based on request-response between the PCP/AP and the non-PCP/non-AP STA.
Meanwhile, a data transfer interval (DTI) is a period in which frame exchange is performed between STAs. One or more contention based access periods (CBAPs) and one or more service periods (SPs) may be allocated as shown in FIG. 4. Although an example in which 2 CBAPs and 2 SPs are allocated is shown in FIG. 4, this is for exemplary purposes only, and the disclosure is not necessarily limited thereto.
Hereinafter, a physical layer configuration for data communication in a wireless AV system to which the present disclosure is applied will be described in detail.
FIG. 5 is a diagram briefly illustrating a configuration of a physical protocol data unit (PPDU) frame according to an embodiment.
Referring to FIG. 5, the PPDU frame may include a legacy-short training field (L-STF), a legacy-channel estimated field (L-CEF), a legacy-header (L-header), an enhanced directional multi-gigabit-header A (EDMG-header A), an EDMG-STF, an DMG-CEF, an EDMG-header B, data, and TRN. These fields may be selectively included according to a PPDU type (e.g., SU PPDU, MU PPDU, etc.). The L-STF includes a training signal. The L-header may include control information for a first legacy station (e.g., a station supporting IEEE802.11ad). The EDMG-header may include control information for a second legacy station (e.g., a station supporting IEEE802.11 ay). The EDMG-STF may include a training signal for the second legacy station.
Herein, control information fields (L-STF, L-CEF, L-header, EDMG header A, EDMG-STF, EDMG-CEF, EDMG-header B) of a physical layer added to a front end of data may be collectively referred to as a preamble. In addition, a part including the L-STF, L-CEF, and L-header fields may be referred to as a non-EDMG region, and the remaining parts may be referred to as an EDMG region. In addition, the L-STF, L-CEF, L-Header, and EDMG-Header-A fields may be referred to as pre-EDMG modulated fields, and the remaining parts may be referred to as EDMG modulated fields.
Returning to FIG. 2, a MIMO channel 11 may be constructed between the plurality of antennas 1150-1, 1150-2, . . . , 1150-NTx and the plurality of antennas 1250-1, 1250-2, . . . , 1250-NRx, and data may be transmitted/received through the MIMO channel 11. Herein, each antenna may be referred to as a DMG antenna or an EDMG antenna.
Hereinafter, in order to implement the present specification, a few assumptions may be made. For example, each antenna may be operated by being connected to an individual RF chain. As another example, reciprocity between antennas may be considered.
A communication circuit (1140, 1210) configures a MIMO channel (11), and a wireless data transmitting device (1100) and a wireless data receiving device (1200) transmit and/or receive data through the MIMO channel (11). The communication circuit (1140, 1210) may perform beamforming (BF) or beamforming training related to MIMO based on multiple antennas (1150-1, 1150-2, . . . , 1150-NTx, 1250-1, 1250-2, . . . , 1250-NRx). The beamforming training relates to transmitting a BF training frame that uses sector sweep and providing necessary signaling to each STA in order to determine an appropriate antenna system setting.
Multiple antennas (1150-1, 1150-2, . . . , 1150-NTx, 1250-1, 1250-2, . . . , 1250-NRx) may be antenna types being capable of performing polarization alignment and may, for example, include a configuration shown in FIG. 6.
FIG. 6 shows multiple antennas having one RF chain being configured of a dual polarization array according to an embodiment of the present specification.
Referring to FIG. 6, for example, multiple antennas (600) include two RF chains (610, 620) and dual polarization arrays (611-1, 611-2, . . . , 611-6, 621-1, 612-2, . . . , 612-6) being connected to each RF chain. One RF chain and a dual polarization array being connected to the one RF chain may be collectively referred to as a DMG antenna or simply referred to as an antenna. That is, a first RF chain (610) and a dual polarization array (611-1, 611-2, . . . , 611-6) being connected thereto may be a first DMG antenna, and a second RF chain (620) and a dual polarization array (621-1, 621-2, . . . , 621-6) being connected thereto may be a second DMG antenna.
A dual polarization array includes multiple dual polarization elements, and a dual polarization element may be referred to as a dual polarization antenna. For example, in linear polarization, the dual polarization element may perform polarization alignment by using poles of two directions, such as a horizontal pole and a vertical pole. Within one dual polarization element, when a signal is transmitted through the horizontal pole, no signal is transmitted through the vertical pole. And, conversely, when a signal is transmitted through the vertical pole, no signal is transmitted through the horizontal pole. As another example, in circular polarization, the dual polarization element may perform polarization alignment by using polarizations of two directions, such as a right-hand circular polarization and a left-hand circular polarization. Within one dual polarization element, when a signal is transmitted through the right-hand circular polarization, no signal is transmitted through the left-hand circular polarization. And, conversely, when a signal is transmitted through the left-hand circular polarization, no signal is transmitted through the right-hand circular polarization.
Each dual polarization element is connected to a polarization synthesis controller, and the polarization synthesis controller may control polarization alignment of the dual polarization element. Additionally, each polarization synthesis controller may be connected to a beamforming controller, and the beamforming controller may control beamforming of the dual polarization element. That is, an individual polarization synthesis controller and beamforming controller may be connected to each dual polarization element. The polarization synthesis controller and the beamforming controller may be configured as an integrated controller or module.
Although the present embodiment limits the number of RF chains to two RF chains and limits the number of dual polarization elements to six dual polarization elements, this is merely exemplary. And, therefore, the number of RF chains may be equal to 1 or 2 or more, and the number of dual polarization elements may be smaller or greater than 6.
FIG. 7 shows a beamforming training process according to an embodiment of the present specification. This corresponds to an operation of the communication circuit (1140, 1210). Hereinafter, an STA that intends to transmit data through a beamforming operation will be referred to as an initiator, and an STA that receives data from the initiator will be referred to as responder. Additionally, a link from the initiator to the responder will be referred to as an initiator link, and a link from the responder to the initiator will be referred to as a responder link.
Referring to FIG. 7, the BF training process includes a Sector Level Sweep (SLS, 700) process selecting a coarse beam in sector units, and a Beam Refinement Protocol (BRP, 710, 720) process selecting a fine beam. That is, the BF training process starts with an SLS from the initiator.
The purpose of the SLS phase (700) is to enable communication between two STAs at a control PHY rate or higher MCS. Most particularly, the SLS phase (700) provides transmitting only BF training. In the SLS phase (700), a coarse transmission direction is determined by using a relatively wide beam. In this phase, a relatively small number of antenna elements may be used. Herein, a transmitter may operate in a Beamforming mode (Directional antenna mode), and a receiver may operate in a Quasi-omni antenna mode. The receiver may receiver a specific signal (e.g., preamble) and may, then, estimate a transmission beam of the transmitter. Therefore, STAs that intend to transmit and/or receive data may mutually know a transmission best sector or reception best sector for an initiator and a responder through the SLS phase (700).
At this point, the SLS phase (700) is a protocol performing link detection in a wireless AV system to which the present specification may be applied, and, herein, by having network nodes contiguously (or consecutively) transmit/receive frames including performance information of a reception channel link by changing only the beam direction, an indicator indicating an optimal frame, among the successfully received frames, may be a beam training scheme that selects the best beam direction.
A more detailed description of the SLS phase (700) is as follows. The SLS Phase (700) may include Initiator TX Sector Sweep (I-TXSS) for training an initiator link, Responder TX Sector Sweep (R-TXSS) for training a responder link, SSW feedback (FBCK), and SSW ACK.
At this point, the initiator may start the SLS phase (700) by transmitting a frame (or frames) of the I-TXSS. The responder does not start the transmission of a frame (or frames) of the R-TXSS before the I-TXSS is successfully completed. However, a case where the I-TXSS occurs within a BTI may be excluded. The initiator may not start the SSW feedback before the R-TXSS phase is successfully completed. However, a case where the R-TXSS occurs within a A-BFT may be excluded. The responder does not start the SSW ACK of the initiator within the A-BFT. The responder may start the SSW ACK of the initiator immediately after the SSW feedback (FBCK) of the initiator has been successfully completed.
The BF frames being transmitted by the initiator during the SLS phase (700) may include an (EDMG) beacon frame, an SSW frame, and an SSW feedback frame. During the SLS process, the BF frames being transmitted by the responder may include an SSW frame and an SSW-ACK frame.
If each of the initiator and the responder performs TXSS during the SLS phase (700), at the end of the SLS phase (700), each of the initiator and the responder may possess its own transmit sector. If the I-TXSS or R-TXSS employs receive sector sweep, the responder or initiator may possess its own receive sector. An STA does not change its transmission power (or transport power) during sector sweep.
At this point, for example, in the above-described SLS Phase (700), the initiator and the responder may use a Short SSW frame. And, for this, the SSW feedback frame and the SSW ACK frame may need to be defined.
When a request is made by the initiator or responder, a Beam Refinement Protocol (or Beam Refinement Phase) (BRP) may be performed subsequent to the SLS phase (700).
The purpose of the BRP phase is to enable reception (RX) training and to enable iterative refinement of an Antenna Weight Vector (AWV) of all transmitters and receivers within all STAs. If one of the STAs participating in the beam training chooses to use a single transmission (TX) antenna pattern, the RX training may be performed as part of the SLS phase (700).
In the BRP phase, a transmission (TX)/reception (RX) beam combination is precisely determined by using a relatively narrow beam. The BRP phase may include a SISO phase and a MIMO phase. The BRP phase may use a relatively larger number of antenna elements as compared to the SLS phase (700) and may increase precision by iterative performance.
As described above, the SISO phase may be performed as a preceding procedure in order to reduce the load of the MIMO phase. And, therefore, the SISO phase may be optionally included in the BRP phase. In case the SISO phase is omitted (or skipped), the BRP phase may be regarded to be the same as the MIMO phase. And, in this case, the BRP phase may also be referred to as a MIMO phase. In the BRP phase, a status enabling minimum communication, such as transmission of a control packet, beacon, and so on, is established, and an optimal beam between the transmitter and the receiver is determined.
The present embodiment discloses a BRP phase in which the SISO phase is omitted (or skipped) or a MIMO phase.
The BRP TXSS according to the present embodiment may include at least one of MIMO BRP TXSS (710), MIMO BRP RXSS (720), and a SU-MIMO phase (730). That is, the BRP phase or MIMO phase according to the present embodiment may include at least one of MIMO BRP TXSS (710) as a first sub-phase, MIMO BRP RXSS (720) as a second sub-phase, and a SU-MIMO phase (730) as a third sub-phase.
The MIMO BRP TXSS (710) includes performing transmit sector training by having the wireless data transmitting device (1100) independently sweep or transmit a sector in parallel per TX antenna, without performing MIMO BRP TXSS (710) on all transmit sector combinations for multiple TX antennas. And, then, the wireless data transmitting device (1100) obtains transmit sector candidates per antenna. By doing so, time (of the SISO phase during MIMO BF) of the BRP TXSS may be shortened (or reduced).
The MIMO BRP RXSS (720) may provide information for selecting a candidate group of a receive sector combination that is to perform the MIMO phase. And, by doing so, the time of the MIMO phase may be reduced. Just as the MIMO BPR TXSS (710), the MIMO BRP RXSS (720) may include a phase independently performing receive sector training in parallel per RX antenna. And, a receive sector candidate may be derived per antenna through the MIMO BRP RXSS (720).
The SU-MIMO phase (730) includes a phase of deriving a best transmit-receive sector combination, among all of the transmit-receive sector combinations.
The present specification proposes a method for overcoming performance degradation due to phase noise that is inevitably applied in a mmWave wireless communication system. In mmWave wireless communication, there is an advantage that a wide bandwidth for data transmission can be used by using a carrier frequency of 30 GHz or higher. However, the problem that the performance of the signal-to-noise ratio at the receiving end decreases due to the fast signal attenuation characteristics according to the distance and the performance deterioration due to the phase noise increases as the carrier frequency increases is a problem that must be overcome in the mmWave wireless communication system. In the present specification, in particular, an algorithm and an apparatus capable of minimizing performance degradation in an environment where independent phase noise between reception antennas is applied is proposed.
FIG. 8 is a graph illustrating a relationship between a frequency offset and a Power Spectral Density (PSD).
Referring to FIG. 8, an x-axis is a frequency offset, and a y-axis is a PSD.
FIG. 8 illustrates a case where the center frequency is 4 GHz, 30 GHz, and 70 GHz.
In the case of the conventional center frequency of 4 GHz, the largest PSD was −100 dBc/Hz, so it did not significantly affect the performance. However, as the center frequency increases to 30 GHz and 70 GHz, the PSD also increases. Referring to FIG. 8, it can be seen that when the center frequency is 30 GHz, the PSD increases by about 20 dBc/Hz more than when the center frequency is 4 GHz.
That is, referring to FIG. 8, as the center frequency (or carrier frequency) increases at the same frequency offset, the PSD value also increases. Powers at a frequency offset of FIG. 8 (eg, 103 Hz (1 KHz), 105 (100 KHz), and 109 (1 GHz)) are powers to be removed because they are noise. Therefore, as the PSD value increases, the phase noise increases.
Accordingly, since the PSD value becomes very large when a center frequency of 70 GHz (60 GHz or more) is used as suggested by this embodiment, phase noise compensation is absolutely necessary. Therefore, a method for estimating and compensating for phase noise will be described below.
The present specification relates to receiver performance and operation of mmWave wireless communication, and more particularly, to an apparatus and method for overcoming performance degradation due to phase noise. Conventionally, in order to compensate for phase noise, the receiving end compensates the phase noise by using a guard interval (GI) period before channel compensation, or compensates the phase noise by using an iterative method after the equalizer.
However, in the prior art, there may be problems in terms of complexity and latency. In addition, when independent phase noise is applied in a multi-Rx antenna environment, the performance gain is not large, and parallel operation is essential in a system requiring high-speed operation. It is not suitable for implementation of parallel operation due to (recursive) operation.
In this specification, in order to compensate for the disadvantages of the existing technology, a method of increasing the performance gain when independent phase noise is applied in a multi-Rx antenna environment by modifying a frequency domain equalizer (FDE) is proposed. In addition, the present specification proposes a method for enabling parallel operation and reducing complexity and latency by using a cross correlation method of GI sections.
A communication system uses an equalization technique based on channel estimation and an appropriate criterion to recover a transmitted signal. In the present specification, an equalization technique to which an MMSE weight according to a minimum mean square error (MMSE) criterion is applied is proposed. First, modeling for the received signal Y may be defined as follows.

Y=Hx+n  [Equation 1]

    
    
        Y Receiving signal vector (vector size: Number of Rx antenna, 1)
        H: Channel matrix (matrix size: Number of Rx antenna, Number of stream)
        x: Transmitting signal vector (vector size: Number of stream, 1)
        n: AWGN vector (vector size: Number of Rx antenna, 1)
        H can be estimated through the channel estimation algorithm and the MMSE
    
    


H can be estimated through the channel estimation algorithm and the MMSE weight matrix can be obtained as follows.

WMMSE=(HHH+σ2I)−1HH[Equation 2]

σ2: Noise variance
WMMSE MMSE weight matrix (matrix size: Number of stream, Number of Rx antenna)
The equalizer module estimates the transmission signal x in the following way.

{circumflex over (x)}=WMMSEY  [Equation 3]

{circumflex over (x)}: an estimated value for transmitting signal vector (Number of stream, 1)
FIG. 9 shows the SC mode frame structure of 802.11ay.
Referring to FIG. 9, a frequency offset may be estimated using a short training field (STF), and a channel may be estimated using a channel estimation field (CEF). In the data field, a GI (Guard Interval) section made of a Golay sequence exists between SC blocks, and phase noise may be estimated through cross-correlation during the GI section in the time domain. One GI and one data field of FIG. 9 may be 512 samples. Common phase noise is applied to each data, and this common phase noise can be compensated through GI. That is, data (n) estimates the phase noise using the GI(n) and GI(n+1) sections.
FIG. 10 shows a block diagram of a receiver of mmWave wireless communication.
Referring to FIG. 10, the receiver estimates phase noise at the IFFT output stage after FDE as shown in FIG. 10 in order to reduce ISI due to the multi-path environment. In order to estimate and compensate for phase noise by extracting only the GI section from a specific path, the signal must be flattened through FDE (like a single-path), and then made into a time domain signal through the IFFT block.
The receiver includes an FDE block, an IFFT block, a phase noise estimator/compensator, and a demodulator. When a time domain signal is received by the receiver, channel estimation is performed by a channel estimator, converted into a frequency domain signal by an FFT block, and channel compensation is performed in the frequency domain by an FDE block. Then, decoding of the signal is performed through the IFFT block, the phase noise estimator/compensator, and the demodulator.
For the i-th SC block of the data field, the IFFT output value can be expressed as follows.



 
  
   
    
     
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        i: SC block index
        k: Symbol index in SC block
        si,k: ith SC block, kth IFFT output symbol vector (Number of stream, 1)
        gm: mth symbol vector of GI part (Number of stream, 1)
        di,k: ith SC block, kth IFFT output symbol vector of Data part (Number of stream, 1)
        NGI Symbol length of GI
        NFFT FFT, IFFT size
    
    


Since the phase noise at the time of channel estimation changes with time, a component due to phase noise actually remains at the IFFT output after FDE. If the phase noise changed compared to the channel estimation time in the i-th SC block is φi, the actual IFFT output terminal ŝi,k can be expressed as follows.

ŝi,k=φisi,k  [Equation 5]

Here, it is assumed that the phase noise is constant during the period taking the IFFT. It is assumed that it is within the coherence time interval. For performance optimization, as shown in FIG. 9, the phase noise of each SC block is estimated using the GIs before and after the corresponding data. That is, data (n) estimates the phase noise using the GI(n) and GI(n+1) sections. The estimated phase noise can be expressed as follows.



 
  
   
    
     
      
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When the phase noise is estimated as in Equation 6, the phase noise for each stream can be estimated. However, when there are two Rx antennas, it is possible to distinguish for each stream, but there is a problem in that the distinction is not made for each Rx. That is, in the case of 1 Tx antenna and 1 Rx antenna, no problem occurs.
In other words, when uncorrelated phase noise for each Rx antenna is applied to the phase noise, the method of Equation 6 may cause performance problems. This is because it is impossible to distinguish each Rx because the phase noise for each Rx has already been combined during FDE.
In a region where the transmission frequency is quite high as 60 GHz, when the distance between the Rx antennas is close, isolation is not sufficient, so that the distance between the Rx antennas is maintained at a certain interval or more. Due to this, a phase lock the loop (PLL) was used independently for the Rx antenna. As a result, phase noise was independently applied for each Rx antenna, and it was the cause of the disappearance of the combine gain for each Rx antenna. Rather, it caused performance degradation when phase noise for each Rx antenna was combined.
Therefore, a method for performing IFFT by decomposing Equation 3 of FDE for each Rx antenna is proposed (ie, FDE is corrected). Taking 2 Rx, 2 Stream as an example, Equation 3 can be arranged as Equation 7 below.



 
  
   
    
     
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The receiver does not perform IFFT for each stream, but performs IFFT on w0,0y0, w0,1y1, w1,0y0, and w1,1y1, respectively (four IFFTs are taken). Therefore, as an IFFT output value, it is possible to obtain results for each stream and each Rx antenna. FDE divides Rx antenna indices 0 and 1 (y0 and y1 can be referred to as Rx antenna indices) and multiplies the MMSE weight matrix to estimate streams 0 and 1. Accordingly, estimation of Rx antenna 0 is also possible and estimation of Rx antenna 1 is also possible.
The phase noise value for each stream in Equation 6 may also be obtained as an estimated value for each Rx antenna as follows.



 
  
   
    
     
      
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               N
               GI
              
              -
              1
             
            
            
             
              (
              
               
                
                 s
                 ^
                
                
                 i
                 ,
                 
                  k
                  -
                  
                   N
                   GI
                  
                 
                 ,
                 1
                 ,
                 0
                
               
               +
               
                
                 s
                 ^
                
                
                 i
                 ,
                 
                  k
                  +
                  
                   N
                   FFT
                  
                  -
                  
                   N
                   GI
                  
                 
                 ,
                 1
                 ,
                 0
                
               
              
              )
             
             ×
             
              g
              k
              *
             
              
            
           
           }
          
          
           For
           ⁢
               
           stream
           ⁢
               
           1
          
         
        
        )
       
      
     
     ⁢
     

     
      
       R
       ×
        
       1
       :
       
        
         φ
         ^
        
        
         i
         ,
         1
        
       
      
      =
      
       
        1
        
         4
         ×
         
          N
          GI
         
        
       
       ⁢
       
        (
        
         
          
           
            
             ∑
             
              k
              =
              0
             
             
              
               N
               GI
              
              -
              1
             
            
            
             
              (
              
               
                
                 s
                 ^
                
                
                 i
                 ,
                 
                  k
                  -
                  
                   N
                   GI
                  
                 
                 ,
                 0
                 ,
                 1
                
               
               +
               
                
                 s
                 ^
                
                
                 i
                 ,
                 
                  k
                  +
                  
                   N
                   FFT
                  
                  -
                  
                   N
                   GI
                  
                 
                 ,
                 0
                 ,
                 1
                
               
              
              )
             
             ×
             
              g
              k
              *
             
              
            
           
           }
          
          
           For
           ⁢
               
           stream
           ⁢
               
           0
          
         
         +
         
          
           
            
             ∑
             
              k
              =
              0
             
             
              
               N
               GI
              
              -
              1
             
            
            
             
              (
              
               
                
                 s
                 ^
                
                
                 i
                 ,
                 
                  k
                  -
                  
                   N
                   GI
                  
                 
                 ,
                 1
                 ,
                 1
                
               
               +
               
                
                 s
                 ^
                
                
                 i
                 ,
                 
                  k
                  +
                  
                   N
                   FFT
                  
                  -
                  
                   N
                   GI
                  
                 
                 ,
                 1
                 ,
                 1
                
               
              
              )
             
             ×
             
              g
              k
              *
             
              
            
           
           }
          
          
           For
           ⁢
               
           stream
           ⁢
               
           1
          
         
        
        )
       
      
     
    
   
   
    
     [
     
      Equation
      ⁢
          
      8
     
     ]
    
   
  
 



Here, ŝi,k,m,n is the k-th sample of the i-th SC block, m is the stream index, and n is the Rx antenna index.
Finally, the demodulator input can be calculated as follows. The input value of the demodulator is the output value of the phase noise estimator/compensator and can be set for each stream.



 
  
   
    
     
      
       Stream
       ⁢
           
       0
       :
        
       
        
         d
         ^
        
        
         i
         ,
         k
         ,
         0
        
       
      
      =
      
       
        
         
          
           s
           ^
          
          
           i
           ,
           k
           ,
           0
           ,
           0
          
         
         ×
         
          
           φ
           ^
          
          
           i
           ,
           0
          
          *
         
        
        
         }
         
          For
          ⁢
              
          Rx
          ⁢
              
          antenna
          ⁢
              
          0
         
        
       
         
       +
       
        
         
          
           
            s
            ^
           
           
            i
            ,
            k
            ,
            0
            ,
            1
           
          
            
          ×
            
          
           
            φ
            ^
           
           
            i
            ,
            1
           
           *
          
         
         
          }
          
           For
           ⁢
               
           Rx
           ⁢
               
           antenna
           ⁢
               
           1
          
         
        
        ⁢
        
         (
         
          0
          ≤
          k
          <
          
           
            N
            FFT
           
           -
           
            N
            GI
           
          
         
         )
        
       
      
     
     ⁢
     

     
      
       Stream
       ⁢
           
       1
       :
        
       
        
         d
         ^
        
        
         i
         ,
         k
         ,
         1
        
       
      
      =
      
       
        
         
          
           s
           ^
          
          
           i
           ,
           k
           ,
           1
           ,
           0
          
         
         ×
         
          
           φ
           ^
          
          
           i
           ,
           0
          
          *
         
        
        
         }
         
          For
          ⁢
              
          Rx
          ⁢
              
          antenna
          ⁢
              
          0
         
        
       
         
       +
       
        
         
          
           
            s
            ^
           
           
            i
            ,
            k
            ,
            1
            ,
            1
           
          
            
          ×
            
          
           
            φ
            ^
           
           
            i
            ,
            1
           
           *
          
         
         
          }
          
           For
           ⁢
               
           Rx
           ⁢
               
           antenna
           ⁢
               
           1
          
         
        
        ⁢
        
         (
         
          0
          ≤
          k
          <
          
           
            N
            FFT
           
           -
           
            N
            GI
           
          
         
         )
        
       
      
     
    
   
   
    
     [
     
      Equation
      ⁢
          
      9
     
     ]
    
   
  
 



In a similar manner, it is possible to estimate and compensate for phase noise for each Rx antenna even in a 1 stream and 2 Rx environment. If the equation for stream 1 in Equation 9 is deleted, it is possible to estimate and compensate for phase noise for each Rx antenna in 1 stream and 2 Rx environment.
The simulation results of the above-described embodiment are shown in FIGS. 11 to 13.
The simulation environment is as follows.

    
    
        Phase noise parameter PLL in-band noise −80 dBc, VCO phase noise @ 1 MHz-100 dBc
        Channel: AWGN, LR-LOS, LR-NLOS
        Number of Stream: 2
        Number of Rx Antenna: 2
        Modulation: 64 QAM
        Number of SC block: 40
    
    


FIG. 11 to FIG. 13 are graphs comparing packet error rates for phase noise compensation.
FIGS. 11 to 13 include all three cases. The first is the case where there is no phase noise and no phase noise compensator is used. Second, there is phase noise and the newly proposed phase noise compensator is used. Third, there is phase noise and the previously proposed phase noise compensator is used. The newly proposed phase noise compensator is a compensator for estimating and compensating for phase noise for each Rx antenna proposed in this embodiment. The previously proposed phase noise compensator is a compensator for estimating and compensating for phase noise for each stream (not distinguishable for each Rx antenna).
FIG. 11 shows the packet error rate for phase noise compensation in the AWGN channel. FIG. 12 shows a packet error rate for phase noise compensation in a Living Room Line Of Sight (LR-LOS). FIG. 13 shows a packet error rate for phase noise compensation in Living Room Non-Line Of Sight (LR-NLOS).
The configuration of the AWGN (Additive White Gaussian Noise) channel is



 
  
   [
   
    
     
      1
     
     
      1
     
    
    
     
      1
     
     
      
       -
       1
      
     
    
   
   ]
  
  ,
 



and the ratio of the off-diagonal item is set to the same power as the diagonal item. In such an environment, the performance degradation of the conventional compensator is quite serious. When compensating by estimating the phase noise between Rx antennas, there is about 0.3 dB performance degradation compared to the situation where no phase noise is applied. But, when the phase noise for each stream is estimated according to the conventional method, almost 100% packet error occurs even at a signal to noise ratio (SNR) of 22 dB.

That is, according to the present embodiment, the receiver performance of mmWave can be improved by estimating and compensating for the uncorrelated phase noise between Rx antennas with low complexity.
Hereinafter, the above-described embodiment will be described with reference to FIGS. 1 to 13.
FIG. 14 is a flowchart illustrating a procedure for demodulating a transmission signal in the receiving device according to the present embodiment.
This embodiment proposes a method for estimating and compensating for phase noise in a multi reception antenna environment in wireless AV (Audio/Video) transmission. In particular, this embodiment proposes a signal demodulation method in which a transmission signal is decomposed for each reception antenna to enable parallel operation. Accordingly, performance degradation due to phase noise may be prevented and complexity and latency may be minimized.
This embodiment will be described from the viewpoint of the receiving device. The receiving device and the transmitting device may be wireless devices supporting mmWave wireless communication. That is, this embodiment describes a method for effectively demodulating a transmitted signal while minimizing performance degradation due to phase noise in a 60 GHz or higher mmWave communication system.
In step S1410, the receiving device estimates a transmission signal based on a Minimum Mean Square Error (MMSE) weight matrix.
In step S1420, the receiving device performs Inverse Fast Fourier Transform (IFFT) by decomposing the estimated transmission signal for each reception antenna.
In step S1430, the receiving device estimates and compensates for phase noise for the each receiving antenna based on the signal on which the IFFT is performed.
In step S1440, the receiving device demodulates the estimated and compensated signals for each stream.
The MMSE weight matrix may be determined based on a channel matrix and noise variance.
The channel matrix may be obtained based on a number of the reception antennas and a number of the streams. The size of the channel matrix may be determined by the number of the reception antennas and the number of the streams. Also, the channel matrix may be estimated through a channel estimation algorithm.
The transmission signal may be transmitted through a single carrier (SC) mode frame.
The SC mode frame may include a Short Training Field (STF), a Channel Estimation Field (CEF), a header field, a plurality of Guard Intervals (GIs), and a plurality of data fields.
The plurality of the GIs may be generated based on a Golay sequence.
The phase noise may be phase noise for the plurality of the data fields.
The phase noise for the plurality of the data fields may be estimated and compensated for by performing cross-correlation during the plurality of the GIs.
A specific embodiment in which the phase noise is estimated and compensated is as follows.
The plurality of the GIs may include first to fourth GIs.
The plurality of the data fields may include first to third data fields.
The first data field may be located between the first and second GIs.
The second data field may be located between the second and third GIs.
The third data field may be located between the third and fourth GIs.
Phase noise for the first data field may be estimated and compensated for during the first and second GIs. Phase noise for the second data field may be estimated and compensated for during the second and third GIs. Phase noise for the third data field may be estimated and compensated for during the third and fourth GIs.
The estimated transmission signal may be decomposed for each of the reception antenna and the stream. The IFFT may be performed on each of the decomposed signals. That is, conventionally, the receiving device performs IFFT for each stream on a signal, but in this embodiment, since IFFT is also performed for each receiving antenna, the receiving device may obtain the output value of the IFFT for each stream as well as the output value for each antenna.
The reception antenna may include first and second reception antennas.
The stream may include a first stream and a second stream.
The estimated value of the phase noise for the first reception antenna may be obtained based on the estimated values of the phase noise for the first and second streams.
The estimated value of the phase noise for the second reception antenna may be obtained based on the estimated values of the phase noise for the first and second streams.
The estimated and compensated signals may be demodulated for each of the first and second streams. That is, signals may be input to the demodulator for each of the first and second streams.
According to the above-described embodiment, demodulation performance of a receiving device supporting mmWave wireless communication may be improved by estimating and compensating for decorrelation phase noise between receiving antennas with low complexity.
FIG. 15 is a block diagram illustrating a receiving device for demodulating a transmission signal according to the present embodiment.
This embodiment proposes a method for estimating and compensating for phase noise in a multi reception antenna environment in wireless AV (Audio/Video) transmission. In particular, this embodiment proposes a signal demodulation method in which a transmission signal is decomposed for each reception antenna to enable parallel operation. Accordingly, performance degradation due to phase noise may be prevented and complexity and latency may be minimized.
This embodiment will be described from the viewpoint of the receiving device. The receiving device and the transmitting device may be wireless devices supporting mmWave wireless communication. That is, this embodiment describes a method for effectively demodulating a transmitted signal while minimizing performance degradation due to phase noise in a 60 GHz or higher mmWave communication system.
The r receiving device includes a Frequency Domain Equalizer (FDE) block, an Inverse Fast Fourier Transform (IFFT) block, a phase noise estimator, a compensator, and a demodulator.
The receiving device may further include an FFT block and a channel estimator. When a time domain transmission signal is received by the receiving device, channel estimation is performed by the channel estimator, and after being converted into a frequency domain signal by the FFT block, channel compensation is performed in the frequency domain by the FDE block.
The FDE block estimates a transmission signal based on a Minimum Mean Square Error (MMSE) weight matrix.
The IFFT block performs IFFT by decomposing the estimated transmission signal for each reception antenna.
The phase noise estimator and compensator estimates and compensates for phase noise for each reception antenna based on the signal on which the IFFT is performed.
The demodulator demodulates the estimated and compensated signals for each stream.
The MMSE weight matrix may be determined based on a channel matrix and noise variance.
The channel matrix may be obtained based on a number of the reception antennas and a number of the streams. The size of the channel matrix may be determined by the number of the reception antennas and the number of the streams. Also, the channel matrix may be estimated through a channel estimation algorithm.
The transmission signal may be transmitted through a single carrier (SC) mode frame.
The SC mode frame may include a Short Training Field (STF), a Channel Estimation Field (CEF), a header field, a plurality of Guard Intervals (GIs), and a plurality of data fields.
The plurality of the GIs may be generated based on a Golay sequence.
The phase noise may be phase noise for the plurality of the data fields.
The phase noise for the plurality of the data fields may be estimated and compensated for by performing cross-correlation during the plurality of the GIs.
A specific embodiment in which the phase noise is estimated and compensated is as follows.
The plurality of the GIs may include first to fourth GIs.
The plurality of the data fields may include first to third data fields.
The first data field may be located between the first and second GIs.
The second data field may be located between the second and third GIs.
The third data field may be located between the third and fourth GIs.
Phase noise for the first data field may be estimated and compensated for during the first and second GIs. Phase noise for the second data field may be estimated and compensated for during the second and third GIs. Phase noise for the third data field may be estimated and compensated for during the third and fourth GIs.
The estimated transmission signal may be decomposed for each of the reception antenna and the stream. The IFFT may be performed on each of the decomposed signals. That is, conventionally, the receiving device performs IFFT for each stream on a signal, but in this embodiment, since IFFT is also performed for each receiving antenna, the receiving device may obtain the output value of the IFFT for each stream as well as the output value for each antenna.
The reception antenna may include first and second reception antennas.
The stream may include a first stream and a second stream.
The estimated value of the phase noise for the first reception antenna may be obtained based on the estimated values of the phase noise for the first and second streams.
The estimated value of the phase noise for the second reception antenna may be obtained based on the estimated values of the phase noise for the first and second streams.
The estimated and compensated signals may be demodulated for each of the first and second streams. That is, signals may be input to the demodulator for each of the first and second streams.
According to the above-described embodiment, demodulation performance of a receiving device supporting mmWave wireless communication may be improved by estimating and compensating for decorrelation phase noise between receiving antennas with low complexity.
Since not all components or steps are essential in the aforementioned wireless data receiving device and method or transmitting device and method, the wireless data receiving device and method or transmitting device and method may be performed by including some or all of the aforementioned components or steps. In addition, embodiments of the aforementioned wireless data receiving device and method or transmitting device and method may be performed in combination with each other. In addition, each of the aforementioned components or steps does not necessarily have to be performed in the order described above, and it is also possible that steps described later are performed prior to steps described earlier.
While the present disclosure has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the appended claims. Therefore, embodiments of the present disclosure described above can be implemented separately or in combination with each other.
Accordingly, the embodiments disclosed in the present disclosure are not intended to limit the technical idea of the present disclosure, but to explain the technical idea, and the scope of the technical idea of the present disclosure is not limited by these embodiments. The scope of protection of the present disclosure should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present disclosure.
The foregoing technical features of this specification are applicable to various applications or business models. For example, the foregoing technical features may be applied for wireless communication of a device supporting artificial intelligence (AI).
Artificial intelligence refers to a field of study on artificial intelligence or methodologies for creating artificial intelligence, and machine learning refers to a field of study on methodologies for defining and solving various issues in the area of artificial intelligence. Machine learning is also defined as an algorithm for improving the performance of an operation through steady experiences of the operation.
An artificial neural network (ANN) is a model used in machine learning and may refer to an overall problem-solving model that includes artificial neurons (nodes) forming a network by combining synapses. The artificial neural network may be defined by a pattern of connection between neurons of different layers, a learning process of updating a model parameter, and an activation function generating an output value.
The artificial neural network may include an input layer, an output layer, and optionally one or more hidden layers. Each layer includes one or more neurons, and the artificial neural network may include synapses that connect neurons. In the artificial neural network, each neuron may output a function value of an activation function of input signals input through a synapse, weights, and deviations.
A model parameter refers to a parameter determined through learning and includes a weight of synapse connection and a deviation of a neuron. A hyper-parameter refers to a parameter to be set before learning in a machine learning algorithm and includes a learning rate, the number of iterations, a mini-batch size, and an initialization function.
Learning an artificial neural network may be intended to determine a model parameter for minimizing a loss function. The loss function may be used as an index for determining an optimal model parameter in a process of learning the artificial neural network.
Machine learning may be classified into supervised learning, unsupervised learning, and reinforcement learning.
Supervised learning refers to a method of training an artificial neural network with a label given for training data, wherein the label may indicate a correct answer (or result value) that the artificial neural network needs to infer when the training data is input to the artificial neural network. Unsupervised learning may refer to a method of training an artificial neural network without a label given for training data. Reinforcement learning may refer to a training method for training an agent defined in an environment to choose an action or a sequence of actions to maximize a cumulative reward in each state.
Machine learning implemented with a deep neural network (DNN) including a plurality of hidden layers among artificial neural networks is referred to as deep learning, and deep learning is part of machine learning. Hereinafter, machine learning is construed as including deep learning.
The foregoing technical features may be applied to wireless communication of a robot.
Robots may refer to machinery that automatically process or operate a given task with own ability thereof. In particular, a robot having a function of recognizing an environment and autonomously making a judgment to perform an operation may be referred to as an intelligent robot.
Robots may be classified into industrial, medical, household, military robots and the like according uses or fields. A robot may include an actuator or a driver including a motor to perform various physical operations, such as moving a robot joint. In addition, a movable robot may include a wheel, a brake, a propeller, and the like in a driver to run on the ground or fly in the air through the driver.
The foregoing technical features may be applied to a device supporting extended reality.
Extended reality collectively refers to virtual reality (VR), augmented reality (AR), and mixed reality (MR). VR technology is a computer graphic technology of providing a real-world object and background only in a CG image, AR technology is a computer graphic technology of providing a virtual CG image on a real object image, and MR technology is a computer graphic technology of providing virtual objects mixed and combined with the real world.
MR technology is similar to AR technology in that a real object and a virtual object are displayed together. However, a virtual object is used as a supplement to a real object in AR technology, whereas a virtual object and a real object are used as equal statuses in MR technology.
XR technology may be applied to a head-mount display (HMD), a head-up display (HUD), a mobile phone, a tablet PC, a laptop computer, a desktop computer, a TV, digital signage, and the like. A device to which XR technology is applied may be referred to as an XR device.
The claims recited in the present specification may be combined in a variety of ways. For example, the technical features of the method claims of the present specification may be combined to be implemented as a device, and the technical features of the device claims of the present specification may be combined to be implemented by a method. In addition, the technical characteristics of the method claim of the present specification and the technical characteristics of the device claim may be combined to be implemented as a device, and the technical characteristics of the method claim of the present specification and the technical characteristics of the device claim may be combined to be implemented by a method.

## Claims

1. A method performed by a receiving device in a wireless audio/video (AV) system, the method comprising:
estimating a transmission signal based on a Minimum Mean Square Error (MMSE) weight matrix,
wherein the transmission signal is estimated as follows:


{circumflex over (x)} =WMMSEY


where, {circumflex over (x)} is an estimated value for a vector of the transmission signal,
WMMSE is the MMSE weight matrix,
Y is a vector of a receiving signal;
performing Inverse Fast Fourier Transform (IFFT) by decomposing the estimated transmission signal for each of first and second reception antennas,
wherein the estimated transmission signal is decomposed for each of first and second reception antennas as follows:




 
  
   [
   
    
     
      
       
        x
        ˆ
       
       0
      
     
    
    
     
      
       
        x
        ˆ
       
       1
      
     
    
   
   ]
  
  =
  
   
    
     [
     
      
       
        
         w
         
          0
          ,
          0
         
        
       
       
        
         w
         
          0
          ,
          1
         
        
       
      
      
       
        
         w
         
          1
          ,
          0
         
        
       
       
        
         w
         
          1
          ,
          1
         
        
       
      
     
     ]
    
    [
    
     
      
       
        y
        0
       
      
     
     
      
       
        y
        1
       
      
     
    
    ]
   
   =
   
    [
    
     
      
       
        
         
          w
          
           0
           ,
           0
          
         
         ⁢
         
          y
          0
         
        
        +
        
         
          w
          
           0
           ,
           1
          
         
         ⁢
         
          y
          1
         
        
       
      
     
     
      
       
        
         
          w
          
           1
           ,
           0
          
         
         ⁢
         
          y
          0
         
        
        +
        
         
          w
          
           1
           ,
           1
          
         
         ⁢
         
          y
          1
         
        
       
      
     
    
    ]
   
  
 


where,




 
  [
  
   
    
     
      w
      
       0
       ,
       0
      
     
    
    
     
      w
      
       0
       ,
       1
      
     
    
   
   
    
     
      w
      
       1
       ,
       0
      
     
    
    
     
      w
      
       1
       ,
       1
      
     
    
   
  
  ]
 



is a MMSE weight matrix for first and second streams,
y0 is an index of the first reception antenna,
y1 is an index of the second reception antenna,




 
  [
  
   
    
     
      
       x
       ˆ
      
      0
     
    
   
   
    
     
      
       x
       ˆ
      
      1
     
    
   
  
  ]
 



is an IFFT output value which obtains results for each of the first and second reception antennas and each of the first and second streams;
estimating and compensating for phase noise for each of the first and second reception antennas based on the signal on which the IFFT is performed; and
demodulating the estimated and compensated signal for each of the first and second streams.

2. The method of claim 1, wherein the MMSE weight matrix is determined based on a channel matrix and noise variance,
wherein the channel matrix is obtained based on a number of the first and second reception antennas and a number of the first and second streams.

3. The method of claim 1, wherein the transmission signal is transmitted through a single carrier (SC) mode frame,
wherein the SC mode frame includes a Short Training Field (STF), a Channel Estimation Field (CEF), a header field, a plurality of Guard Intervals (GIs), and a plurality of data fields,
wherein the plurality of the GIs are generated based on a Golay sequence,
wherein the phase noise is phase noise for the plurality of the data fields,
wherein the phase noise for the plurality of the data fields is estimated and compensated by performing cross-correlation during the plurality of the GIs.

4. The method of claim 3, wherein the plurality of the GIs include first to fourth GIs,
wherein the plurality of the data fields include first to third data fields,
wherein the first data field is located between the first and second GIs;
wherein the second data field is located between the second and third GIs;
wherein the third data field is located between the third and fourth GIs.

5. The method of claim 4, wherein a phase noise for the first data field is estimated and compensated for during the first and second GIs,
wherein a phase noise for the second data field is estimated and compensated for during the second and third GIs,
wherein a phase noise for the third data field is estimated and compensated for during the third and fourth GIs.

6. The method of claim 1, wherein the estimated transmission signal is decomposed for each of the first and second reception antennas and the first and second streams,
wherein the IFFT is performed on each of the decomposed signals.

7. The method of claim 6,
wherein the estimated value of the phase noise for the first reception antenna is obtained based on the estimated value of the phase noise for the first and second streams,
wherein the estimated value of the phase noise for the second reception antenna is obtained based on the estimated value of the phase noise for the first and second streams.

8. The method of claim 7, wherein the estimated and compensated signals are demodulated for each of the first and second streams.

9. A receiving device in a wireless audio/video (AV) system, the receiving device comprising:
a Frequency Domain Equalizer (FDE) block;
A Inverse Fast Fourier Transform (IFFT) block;
a phase noise estimator and compensator; and
a demodulator,
wherein the FDE block estimates a transmission signal based on a Minimum Mean Square Error (MMSE) weight matrix,
wherein the transmission signal is estimated as follows:


{circumflex over (x)}=WMMSEY


where, {circumflex over (x)} is an estimated value for a vector of the transmission signal,
WMMSE is the MMSE weight matrix,
Y is a vector of a receiving signal,
wherein the IFFT block performs IFFT by decomposing the estimated transmission signal for each of first and second reception antennas,
wherein the estimated transmission signal is decomposed for each of first and second reception antennas as follows:




 
  
   [
   
    
     
      
       
        x
        ˆ
       
       0
      
     
    
    
     
      
       
        x
        ˆ
       
       1
      
     
    
   
   ]
  
  =
  
   
    
     [
     
      
       
        
         w
         
          0
          ,
          0
         
        
       
       
        
         w
         
          0
          ,
          1
         
        
       
      
      
       
        
         w
         
          1
          ,
          0
         
        
       
       
        
         w
         
          1
          ,
          1
         
        
       
      
     
     ]
    
    [
    
     
      
       
        y
        0
       
      
     
     
      
       
        y
        1
       
      
     
    
    ]
   
   =
   
    [
    
     
      
       
        
         
          w
          
           0
           ,
           0
          
         
         ⁢
         
          y
          0
         
        
        +
        
         
          w
          
           0
           ,
           1
          
         
         ⁢
         
          y
          1
         
        
       
      
     
     
      
       
        
         
          w
          
           1
           ,
           0
          
         
         ⁢
         
          y
          0
         
        
        +
        
         
          w
          
           1
           ,
           1
          
         
         ⁢
         
          y
          1
         
        
       
      
     
    
    ]
   
  
 


where,




 
  [
  
   
    
     
      w
      
       0
       ,
       0
      
     
    
    
     
      w
      
       0
       ,
       1
      
     
    
   
   
    
     
      w
      
       1
       ,
       0
      
     
    
    
     
      w
      
       1
       ,
       1
      
     
    
   
  
  ]
 



is a MMSE weight matrix for first and second streams,
y0 is an index of the first reception antenna,
y1 is an index of the second reception antenna,




 
  [
  
   
    
     
      
       x
       ˆ
      
      0
     
    
   
   
    
     
      
       x
       ˆ
      
      1
     
    
   
  
  ]
 



is an IFFT output value which obtains results for each of the first and second reception antennas and each of the first and second streams,
wherein the phase noise estimator and compensator estimates and compensates for phase noise for each of the first and second reception antennas based on the signal on which the IFFT is performed,
wherein the demodulator demodulates the estimated and compensated signals for each of the first and second streams.

10. The receiving device of claim 9, wherein the MIVISE weight matrix is determined based on a channel matrix and noise variance,
wherein the channel matrix is obtained based on a number of the first and second reception antennas and a number of the first and second streams.

11. The receiving device of claim 9, wherein the transmission signal is transmitted through a single carrier (SC) mode frame,
wherein the SC mode frame includes a Short Training Field (STF), a Channel Estimation Field (CEF), a header field, a plurality of Guard Intervals (GIs), and a plurality of data fields,
wherein the plurality of the GIs are generated based on a Golay sequence,
wherein the phase noise is phase noise for the plurality of the data fields,
wherein the phase noise for the plurality of the data fields is estimated and compensated by performing cross-correlation during the plurality of the GIs.

12. The receiving device of claim 11, wherein the plurality of the GIs include first to fourth GIs,
wherein the plurality of the data fields include first to third data fields,
wherein the first data field is located between the first and second GIs;
wherein the second data field is located between the second and third GIs;
wherein the third data field is located between the third and fourth GIs.

13. The receiving device of claim 12, wherein a phase noise for the first data field is estimated and compensated for during the first and second GIs,
wherein a phase noise for the second data field is estimated and compensated for during the second and third GIs,
wherein a phase noise for the third data field is estimated and compensated for during the third and fourth GIs.

14. The receiving device of claim 9, wherein the estimated transmission signal is decomposed for each of the first and second reception antennas and the first and second streams,
wherein the IFFT is performed on each of the decomposed signals.

15. The receiving device of claim 14,
wherein the estimated value of the phase noise for the first reception antenna is obtained based on the estimated value of the phase noise for the first and second streams,
wherein the estimated value of the phase noise for the second reception antenna is obtained based on the estimated value of the phase noise for the first and second streams.

16. The receiving device of claim 15, wherein the estimated and compensated signals are demodulated for each of the first and second streams.