IP multicast wireless transmission system and capsule device

Abstract

IP multicast is transmitted wirelessly from a transmitting device to a receiving device with stable transmission quality. [Solution] An IP multicast wireless transmission system transmits IP multicast packets from a transmitter to one or more receivers via unidirectional communication. The transmitter and receiver are equipped with wireless communication units for WHDI or WirelessHD transmission, which transmit and receive video signals via radio waves. The system also includes a first control device that encapsulates IP multicast packets in a video signal format transmittable via WHDI or WirelessHD transmission and outputs the encapsulated data to the transmitter, and a second control device that extracts IP multicast packets from the video signal output from the receiver. Data is sent using FEC, which corrects errors that occur on the transmission path between the transmitter and receiver at the receiver side.

Description

[Technical Field]

[0001] The present invention relates to a wireless transmission technique for IP multicast packets. [Background technology]

[0002] For example, IP multicast packets provided by an IP multicast broadcasting provider are sent over an IP network to the viewer's line terminating device (ONU, home gateway (HGW), CATV modem, ADSL modem, CTU, etc.) The line terminating device transmits the IP multicast packets to an STB (set-top box), which then displays the images on a display such as an LCD display. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-187626 [Non-patent literature]

[0004] [Non-Patent Document 1] Japan Cable Labs JLabs DOC-103 1.0.1 "Home Wi-Fi Guidelines for IP Broadcasting" published on September 24, 2024 Summary of the Invention [Problem to be solved by the invention]

[0005] For example, in order to watch video provided by an IP multicast broadcasting provider, it is necessary to connect and set up devices such as line termination devices and STBs using HDMI cables, LAN cables, etc. While IP broadcasting has mainly been performed in connection environments based on wired communication, in recent years efforts have been made to build connection environments based on wireless communication, and as described in Non-Patent Document 1, attempts are being made to create a one-to-many wireless communication environment in communication between line termination devices and STBs that allows viewers to watch IP broadcasts on multiple display devices.

[0006] However, when transmitting IP multicast packets from a transmitting device to a receiving device via wireless communication, the required transmission quality cannot be maintained with wireless communication based on the Wi-Fi (registered trademark) standard, making IP multicast communication of video signals difficult (for example, Patent Document 1).

[0007] There have been various approaches to this issue, such as improving FEC error correction technology to maintain transmission quality while using Wi-Fi wireless communication, or converting multicast packets to unicast packets for transmission in Wi-Fi wireless communication. There have also been attempts to use multiple bidirectional transmission paths and employ ARQ (Automatic Repeat reQuest) error correction technology to achieve high quality. However, these technical approaches have not provided a fundamental solution.

[0008] While one-to-one or one-to-many communication over Wi-Fi (IP-based wireless communication) is possible at low transmission rates and over short distances, it is difficult to transmit at high transmission rates and over medium distances, and it is not possible to provide stable transmission quality. Furthermore, when multicast packets are converted to unicast packets over Wi-Fi for transmission, error correction using the ARQ method is required, making it necessary to use a bidirectional transmission path. The ARQ error correction method, not limited to Wi-Fi wireless communication, cannot be applied to unidirectional data transmission.

[0009] An object of the present invention is to provide an IP multicast wireless transmission system that can transmit IP multicast from a transmitting device to a receiving device via wireless communication with stable transmission quality. [Means for solving the problem]

[0010] (1) The present invention is an IP multicast wireless transmission system that transmits IP multicast packets from a transmitting device to one or more receiving devices via one-way communication, and the transmitting device and receiving device are equipped with wireless communication units that use the WHDI transmission method or WirelessHD transmission method to transmit and receive video signals via radio waves.

[0011] The IP multicast wireless transmission system comprises a first control device that encapsulates IP multicast packets into a video signal format that can be transmitted using the WHDI transmission method or the WirelessHD transmission method and outputs the encapsulated IP multicast packets to a transmitting device, and a second control device that extracts IP multicast packets from the video signal output from the receiving device, and can be configured so that data is sent using an FEC method that corrects errors that occur on the transmission path between the transmitting device and the receiving device at the receiving device side. The first control device includes the following components. an outer coding unit that performs an outer code coding process on each of a plurality of fixed-length data generated by dividing an IP multicast packet into byte data of predetermined fixed lengths to generate an outer-code parity bit, and that generates outer-coded data by concatenating the fixed-length data and the outer-code parity bit corresponding to the fixed-length data; an interleaving unit that rearranges each of the outer-coded data arranged in the transmission order of the IP multicast packets in a direction perpendicular to the scanning lines of the video signal frame and performs interleaving to assign the outer-coded data as pixels of the video signal; an inner coding unit that extracts, in the scanning line direction, the outer coded data rearranged in a direction perpendicular to the scanning lines, performs an inner code encoding process on the extracted data to generate an inner code parity bit, and adds the inner code parity bit to the extracted data to generate inner coded data; An output unit that converts the internally encoded data into a video signal that can be transmitted using the WHDI transmission method or the WirelessHD transmission method, and outputs it to a transmitting device.

[0013] ( 2 )the above( 1), the first control device may further include a data control unit that divides an IP multicast packet into byte data of a predetermined fixed length to generate a plurality of fixed-length data, and adds a synchronization pattern indicating a delimiter of the IP multicast packet to each fixed-length data. In this case, the outer coding unit may perform an outer code coding process on each fixed-length data to which the synchronization pattern has been added to generate an outer-code parity bit, and may generate the outer-coded data by concatenating the fixed-length data to which the synchronization pattern has been added and the outer-code parity bit corresponding to the fixed-length data to which the synchronization pattern has been added.

[0014] In addition, the first control device can be provided with a save unit that performs a save process to swap the order of vertical and horizontal bits of the internally encoded data, and the output unit can be configured to convert the data string after the save process into a video signal to be transmitted using the WHDI transmission method or the WirelessHD transmission method and output it to the transmitting device.

[0015] ( 3 )the above( 1 ) the second control device includes the following configuration. an inner code decoding unit that performs error correction processing based on an inner code parity bit included in the inner coded data and generates data extracted in the scanning line direction; a deinterleave unit that performs deinterleaving processing to rearrange the data extracted in the scanning line direction in a direction perpendicular to the scanning line, and generates outer coded data arranged in the transmission order of the IP multicast packets; an outer code decoding unit that performs error correction processing based on the outer code parity bits included in the deinterleaved outer coded data and generates fixed length data that constitutes an IP multicast packet; a concatenation unit that concatenates the decoded fixed-length data; and A packet control unit that extracts IP multicast packets based on the linked fixed-length data group.

[0016] ( 4 ) The present invention is an IP multicast wireless transmission system that transmits IP multicast packets from a transmitter to one or more receivers via unidirectional communication, and the transmitter and receiver are equipped with wireless communication units that use the WHDI or WirelessHD transmission method to transmit and receive video signals via radio waves. The IP multicast wireless transmission system includes a first control device that encapsulates IP multicast packets in a video signal format that can be transmitted using the WHDI or WirelessHD transmission method and outputs the encapsulated video signals to the transmitter, and a second control device that extracts IP multicast packets from the video signals output from the receiver, and can be configured so that data is sent using an FEC method that corrects errors that occur on the transmission path between the transmitter and receiver at the receiver side. and, The first control device includes the following components. Multiple packets generated by dividing an IP multicast packet into byte data of a predetermined fixed length For each fixed-length data, the fixed-length data is divided into a plurality of pieces of data with a plurality of byte lengths, a data control unit that allocates each of the divided byte-length data to a different divided area; The byte-length data is subjected to outer code encoding processing to generate outer code parity bits, and The outer-coded data is generated by concatenating the byte-length data with the outer-code parity bit corresponding to the byte-length data. The outer coding process to generate data is performed for each divided area to which byte-length data is assigned. outer encoding section, For each divided area, the outer coded data arranged in the transmission order of the IP multicast packets is The pixels of the video signal are rearranged in a direction perpendicular to the scanning lines of the frame, and the outer coded data is an interleaving unit that performs interleaving to allocate For each divided area, the outer coded data rearranged in the direction perpendicular to the scanning line is The extracted data string is generated, and the data strings corresponding to each of the divided regions are concatenated. The data sequence group is subjected to an inner code encoding process to generate an inner code parity bit. The inner code parity bit is allocated to a separate area from the area to which the byte-length data is allocated. an inner coding unit for assigning the region; and Each data string generated for each divided area and the inner code parity bit are transmitted in the WHDI transmission system or is an output that is converted into a video signal to be transmitted using the WirelessHD transmission method and output to a transmitter. Department.

[0017] ( 5 )the above( 4), the data control unit can be configured to divide an IP multicast packet into byte data of a predetermined fixed length to generate a plurality of fixed-length data, add a synchronization pattern indicating the delimitation of the IP multicast packet to each fixed-length data, divide the fixed-length data with the synchronization pattern added into a plurality of byte-length data, and assign each of the divided byte-length data to a different divided area.

[0018] In addition, the first control device can be configured to have a save unit that performs a save process to swap the order of vertical and horizontal bits of data on the data strings of each divided area generated in the inner coding unit and the inner code parity bits of another divided area, and the output unit can be configured to convert each data string and inner code parity bits after the save process into a video signal to be transmitted using the WHDI transmission method or the WirelessHD transmission method and output it to the transmitting device.

[0019] ( 6 )the above( 4 ) the second control device includes the following configuration. an inner code decoding unit that performs error correction processing based on inner code parity bits assigned to other divided areas and generates a data sequence group by concatenating data sequences corresponding to each of the plurality of divided areas; a deinterleave unit that allocates the inner-coded decoded data strings to corresponding divided regions, performs deinterleaving processing for rearranging the data strings cut out in the scanning line direction for each divided region in a direction perpendicular to the scanning line, and generates outer-coded data arranged in the transmission order of the IP multicast packets; an outer code decoding unit that performs error correction processing based on an outer code parity bit included in the deinterleaved outer coded data for each divided region, and generates byte length data; a synthesis unit that synthesizes the corresponding byte-length data assigned to each divided area and generates fixed-length data; a linking section for linking the synthesized fixed-length data; and A packet control unit that extracts IP multicast packets based on the linked fixed-length data group.

[0020] ( 7 ) The present invention is an encapsulation device that receives IP multicast packets provided by a data source and encapsulates the IP multicast packets into a video signal format that can be transmitted using the WHDI transmission method or the WirelessHD transmission method.

[0021] The encapsulation device includes an outer coding unit that performs an outer code coding process on each of a plurality of fixed-length data generated by dividing the IP multicast packet into byte data of a predetermined fixed length to generate an outer code parity bit, and generates outer-coded data by concatenating the fixed-length data and the outer code parity bit corresponding to the fixed-length data; an interleaving unit that rearranges each of the outer-coded data arranged in the transmission order of the IP multicast packets in a direction perpendicular to the scanning lines of the video signal frame and performs interleaving to assign the outer-coded data as pixels of the video signal; an inner coding unit that extracts, in the scanning line direction, the outer coded data rearranged in a direction perpendicular to the scanning lines, performs an inner code encoding process on the extracted data to generate an inner code parity bit, and adds the inner code parity bit to the extracted data to generate inner coded data; It is equipped with an output unit that converts the internally encoded data into a video signal that can be transmitted using the WHDI transmission method or the WirelessHD transmission method and outputs it. [Effects of the Invention]

[0022] According to the present invention, in IP multicasting from a transmitting device to one or more receiving devices via one-way communication, the wireless communication between the transmitting device and receiving device is configured using the WHDI transmission method or WirelessHD transmission method, which transmits and receives video signals via radio waves, and the IP multicast packets are encapsulated in the video signals and transmitted, enabling high-transmission-rate, medium-distance transmission.In addition, since data is sent using the FEC (forward error correction) method, transmission errors can be corrected on the receiving side without retransmitting the data, and data can be received without delay.As a result, wireless communication from the transmitting device to one or more receiving devices can be performed with stable transmission quality. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a schematic diagram of an IP multicast wireless transmission system according to a first embodiment. [Figure 2] FIG. 2 is a functional block diagram of a first control device (transmission side) of the first embodiment. [Figure 3] 3 is a diagram for explaining various processes of fixed-length division, synchronization pattern addition, outer coding, interleaving, and inner coding performed by the first control device (transmission side) of the first embodiment. FIG. [Figure 4] FIG. 10 is a diagram for explaining the saving process (bit interleaving) of the first control device (transmission side) of the first embodiment. [Figure 5] FIG. 4 is a functional block diagram of a second control device (receiving side) in the first embodiment. [Figure 6] FIG. 2 is a functional block diagram of a first control device (receiving side) that encapsulates IP multicast packets into video signals corresponding to a plurality of data areas in the first embodiment. [Figure 7] 10A to 10C are diagrams for explaining various processes when an IP multicast packet is encapsulated into a video signal corresponding to a plurality of data areas in the first embodiment. [Figure 8] 10A and 10B are diagrams for explaining the inner coding process when an IP multicast packet is encapsulated into a video signal corresponding to a plurality of data areas in the first embodiment. [Figure 9] FIG. 10 is a functional block diagram of a second control device (receiving side) that supports encapsulating IP multicast packets into video signals that correspond to a plurality of data areas in the first embodiment. BEST MODE FOR CARRYING OUT THE INVENTION

[0024] Hereinafter, embodiments will be described with reference to the drawings.

[0025] (First embodiment) 1 to 9 are diagrams for explaining the first embodiment. Fig. 1 is a schematic diagram of an IP multicast wireless transmission system of this embodiment.

[0026] The IP multicast wireless transmission system of this embodiment realizes IP multicast by wireless communication from a transmitter T to one or more receivers R via unidirectional communication, and includes a first control device 10 to which IP multicast packets distributed from a sender (data source) such as a distribution company are input, the transmitter T connected to the first control device 10, multiple receivers R paired with the transmitter T, and multiple second control devices 20 (20A to 20C) connected to each receiver R. A device D is connected to each second control device 20.

[0027] The following describes an example in which a signal is transmitted from one transmitting device T to multiple receiving devices R via one-way communication, but the present invention is not limited to this and may also be configured to transmit a signal from one transmitting device T to one receiving device R. In other words, the IP multicast wireless transmission system of this embodiment can realize one-to-one or one-to-many IP multicast via wireless communication. Note that one-way communication (Simplex Communication) is a communication path or communication method that can only send signals or data in one specific direction.

[0028] The transmitting device T and the receiving device R are equipped with wireless communication units Tt, Rt that use the WHDI transmission method or WirelessHD transmission method to transmit and receive video signals via radio waves, and a non-IP wireless transmission path is formed between the transmitting device T and the receiving device R. Hereinafter, the WHDI transmission method or WirelessHD transmission method will be referred to as the non-IP wireless transmission method.

[0029] The wireless communication unit Tt of the transmitting device T has a transmission function of transmitting a video signal to the wireless communication unit Rt of the receiving device R using a non-IP wireless transmission method, and the wireless communication unit Rt of the receiving device R has a receiving function of receiving the video signal transmitted from the transmitting device T.

[0030] In the case of the WirelessHD transmission method, for example, a non-IP wireless transmission method can transmit uncompressed or compressed data to a receiving side using a high-rate physical layer (HRP) communication method. HRP is a one-way communication method suitable for transmitting large amounts of data. The wireless communication unit Tt of the transmitting device T performs communication in accordance with the WirelessHD transmission method, for example, by establishing a communication channel using the HRP and transmitting data via the communication channel. The same is true for the WHDI transmission method, where a communication channel is established using a predetermined communication method and uncompressed or compressed data is transmitted to the receiving side.

[0031] The WHDI transmission system or WirelessHD transmission system can use known technologies as appropriate. The WHDI transmission system or WirelessHD transmission system is a transmission system that is premised on transmitting video signal streams (non-IP wireless communication), and cannot transmit IP packets.

[0032] IP multicast is a communication format that delivers the same data (IP packets) to multiple recipients (devices belonging to a specific group) in a single communication, and the sender can manage multiple users (destinations) to whom IP multicast packets will be delivered in advance as a group.

[0033] Examples of IP multicast usage scenarios include content distribution (video distribution, live video distribution, etc.) and IP broadcasting. In content distribution and IP broadcasting, IP multicast packets containing video data are distributed. On the other hand, software (program) distribution can also be performed using IP multicast. In this case, IP multicast packets containing programs and modules that make up the software are multicast. The IP multicast wireless transmission system of this embodiment is not limited to video data and can be applied to IP multicast containing any information depending on the usage scenario of the IP multicast.

[0034] The non-IP wireless transmission method can transmit radio waves conforming to video signal standards such as HDMI signals (HDMI is a registered trademark) and SDI signals (SD-SDI, MD-SDI), and encapsulates IP multicast packets in a video signal standard that can be transmitted by the non-IP wireless transmission method (for example, embedding a byte sequence that makes up the IP multicast packet in a full HD (1920 x 1080 pixel) video frame), and wirelessly transmits the video signal with the IP multicast packets embedded as pixels from a transmitting device T to each of multiple receiving devices R.

[0035] In the IP multicast wireless transmission system of this embodiment, there is no particular limitation on the type of information encapsulated in the IP multicast packet, and the IP multicast may be an IP multicast packet containing video data or may be an IP multicast packet containing information other than video data. Note that the format of the video signal that can be transmitted by a non-IP wireless transmission method can be set arbitrarily.

[0036] In the case of content distribution or IP broadcasting, the device D connected to the second control device 20 is, for example, a device that is connected to a display device such as a set-top box (STB) and displays content such as videos. A computer device can also be used to view videos and can be configured as the device D. The same is true in the case of software distribution; an STB, a display device, or a computer device that runs on an operating system, applications, and various programs can be configured as the device D.

[0037] As mentioned above, wireless communication based on the Wi-Fi (registered trademark) standard, which is a representative standard for IP communication, has the problem of being unable to maintain the transmission quality of one-to-one or one-to-many IP multicast packets. Various approaches have been attempted to address this problem, but it has been difficult to achieve high transmission rates and medium-distance transmission, and it has not been possible to provide stable transmission quality.

[0038] As shown in Figure 1, the IP multicast wireless transmission system of this embodiment is configured so that communication between transmitting device T and receiving device R is configured using a non-IP wireless transmission method in which video signals are transmitted and received via radio waves, and the system is equipped with a first control device 10 that encapsulates IP multicast packets in the format of a video signal for transmitting device T, and a second control device 20 that extracts IP multicast packets from the video signal input from receiving device R.

[0039] That is, the wireless transmission path from the transmitting device T to the receiving device R is configured using a non-IP wireless transmission method, rather than an IP wireless communication method such as Wi-Fi, and IP multicast packets are encapsulated in the video signal. The non-IP wireless transmission method is capable of high transmission rate and medium distance transmission (e.g., 30 m, 3 Gbps), and in IP multicast, wireless transmission from one transmitting device T to one or multiple receiving devices R can be performed with stable transmission quality.

[0040] Furthermore, FEC (Forward Error Correction) is adopted to correct errors that occur in the non-IP wireless transmission path between the transmitting device T and the receiving device R on the receiving device R side, so that transmission errors can be corrected on the receiving side without retransmitting the data, allowing data to be received without delay.

[0041] As described above, the IP multicast wireless transmission system of this embodiment is equipped with wireless communication units Tt, Rt that use the WHDI transmission method or WirelessHD transmission method for transmitting and receiving video signals via radio waves in the transmitter T and receiver R, and transmits IP multicast packets from the transmitter T to the receiver R via one-way communication. The system is also equipped with a first control unit 10 that encapsulates the IP multicast packets in a video signal format that can be transmitted using the WHDI transmission method or WirelessHD transmission method and outputs the encapsulated IP multicast packets to the transmitter T, and a second control unit 20 that extracts the IP multicast packets from the video signal output from the receiver R, and is configured so that data is sent using the FEC method, which corrects errors that occur on the transmission path between the transmitter T and receiver R at each receiver R side.

[0042] In the present embodiment, the first control device 10 and the transmitting device T are configured as separate devices, but the first control device 10 and the transmitting device T may be configured as an integrated device. The same applies to the second control device 20 and the receiving device R, and the second control device 20 and the receiving device R may be configured as an integrated device.

[0043] <Explanation of the first control device> 2 is a functional block diagram of the first control device 10 of this embodiment. The input side of the first control device 10 is connected to a data source, and the output side is connected to a transmitting device T. IP multicast packets are input from the data source to the first control device 10. The transmission paths between the data source and the first control device 10 and between the first control device 10 and the transmitting device T can be configured as wired or wireless paths.

[0044] As shown in FIG. 2, the first control device 10 includes a data control unit 101, an outer coding unit 102, an interleaving unit 103, an inner coding unit 104, a saving unit 105, and an output unit .

[0045] 3 and 4 are diagrams for explaining various processes of the first control device 10. The first control device 10 is a capsule device that performs processes in the order of fixed-length division, synchronization pattern addition, outer coding, interleaving, inner coding, and evacuation processing, and generates a video signal in which an IP multicast packet is encapsulated.

[0046] As shown in Figure 3, the data control unit 101 performs fixed-length division processing and synchronization pattern addition processing. The input IP multicast packet is divided into byte data of a predetermined fixed length to generate multiple fixed-length data. At this time, a synchronization pattern indicating the delimitation of the IP multicast packet is added to each fixed-length data. Any blank spaces after division into fixed lengths can be filled with NULLs. The fixed length is arbitrary.

[0047] Next, the outer coding unit 102 performs outer coding processing. For each fixed-length data to which a synchronization pattern has been added, outer code coding processing is performed to generate outer-code parity bits, and outer-coded data is generated by concatenating the fixed-length data to which the synchronization pattern has been added and the outer-code parity bits corresponding to the fixed-length data to which the synchronization pattern has been added.

[0048] The interleaving unit 103 rearranges each of the outer coded data arranged in the transmission order of the IP multicast packet in a direction perpendicular to the scanning lines of the frame based on a predetermined video signal format that can be transmitted using a non-IP wireless transmission method, and performs interleaving to assign the outer coded data as pixels of the video signal.

[0049] The inner coding unit 104 extracts the outer-coded data rearranged in a direction perpendicular to the scanning lines in the scanning line direction, performs inner-code encoding processing on the extracted data to generate inner-code parity bits, and adds the generated inner-code parity bits to the extracted data to generate inner-coded data.

[0050] The saving unit 105 performs a saving process that swaps the vertical and horizontal bit order of the inner-coded data along the data transmission direction (direction of wireless transmission). This saving process is bit interleaving. For example, as shown in FIG. 4, the inner-coded data is associated with each pixel that makes up a frame of a video signal. If one pixel is, for example, one byte, the information contained in one pixel is eight bits. The eight-bit data string is arranged in order from the most significant bit (MSB) to the least significant bit (LSB).

[0051] The saving unit 105 performs bit interleaving on each pixel of the inner-coded data arranged in the data transmission direction. In the example of FIG. 4, the vertical and horizontal transposition of a data string of one pixel (8 bits) arranged vertically is performed. In this case, it is possible to set the number of bits from the MSB to be transposed in the 8-bit data string after vertical and horizontal transposition. For example, if the arrangement position N from the MBS is set to 5, the transposed bits of the inner-coded data are arranged from the MBS to the fifth bit in the data example of one pixel after transposition, and the sixth to eighth bits can be filled with NULL or any other numeric value. Note that although an example of a data string with one pixel being 8 bits has been described, a data string with one pixel being 24 bits may also be used, and the data capacity corresponding to one pixel can be set appropriately.

[0052] The output unit 106 converts the data string after the saving process into a video signal of a non-IP wireless communication method, and outputs the video signal (video stream) in which the IP multicast packet is encapsulated to the transmitting device T.

[0053] As described above, wireless communication between a transmitting device T and each of multiple receiving devices R is configured using a non-IP wireless transmission method, and IP multicast packets are encapsulated in a predetermined video signal format, so even in one-to-many IP multicast, wireless communication from one transmitting device T to each of multiple receiving devices R can be performed with stable transmission quality.

[0054] On the other hand, the WHDI and WirelessHD transmission methods allow a certain amount of information loss so that the bit error rate (BER) does not deteriorate significantly. However, since information loss due to uncorrectable transmission errors affects transmission quality, it is best to have as few uncorrectable transmission errors as possible.

[0055] FEC (Forward Error Correction) allows the receiving side to correct transmission errors without retransmitting the data, and allows data to be extracted without delay on the receiving side, but it still generates a certain bit error rate (BER). For this reason, how to prevent degradation of transmission quality due to information loss is an important aspect in wireless communication technology. For example, in IP multicast communications including video data, information loss can cause the video to become distorted or cut off, so it is particularly important to prevent degradation of transmission quality due to information loss.

[0056] Therefore, as a mechanism for suppressing degradation of transmission quality due to information loss, the first control device 10 of this embodiment is configured to perform interleaving between the outer coding and inner coding processes to suppress information loss due to burst errors. Also, a saving process is performed to avoid the influence of discarding several bits of information on the LSB (least significant bit) side.

[0057] In this embodiment, the interleaving rearranges each piece of outer-coded data arranged in the transmission order of the IP multicast packet in a direction perpendicular to the scanning lines of a frame based on a predetermined video signal format that can be transmitted using a non-IP wireless transmission system, and assigns the outer-coded data as pixels of the video signal. Therefore, even if an entire scanning line is lost due to a burst error, only one byte of outer-coded data arranged in a direction perpendicular to the scanning lines of the frame is lost, and the data can be decoded properly (effectively) by error correction processing based on the outer code parity bit. As will be described later, for example, in a 1920 x 1080 pixel video signal, if the outer-coded data is 120 bytes long, up to 54 missing scanning lines can be effectively corrected.

[0058] Furthermore, while non-IP wireless transmission methods can transmit uncompressed video signals, the WHDI transmission method or WirelessHD transmission method can also transmit video signals after undergoing video signal compression processing (lossy compression). Lossy compression can reduce data size while maintaining quality and shorten processing time, enabling efficient data processing. During video signal compression processing (lossy compression), several bits of information on the LSB (least significant bit) side are discarded. Therefore, in this embodiment, a backup process is performed as a mechanism to avoid the impact of discarding several bits of information on the LSB (least significant bit) side that are performed during video signal compression processing (lossy compression).

[0059] Note that the saving process is applied taking into consideration the video signal compression process (irreversible compression) when the transmitting device T transmits the video signal to the receiving device R. Therefore, for example, if the transmitting device T transmits the video signal uncompressed without performing the video signal compression process, the saving process (saving unit 105) can be omitted.

[0060] <Explanation of the second control device> 5 is a functional block diagram of the second control device 20 of this embodiment. The input side of the second control device 20 is connected to the receiving device R, and the output side is connected to the device D. A video signal (IP multicast packet encapsulated in a video signal) is input from the receiving device R to the second control device 20. The transmission paths between the receiving device R and the second control device 20 and between the second control device 20 and the device D can be configured as wired or wireless paths.

[0061] As shown in Fig. 5, the second control device 20 includes an input unit 201, a restoration unit 202, an inner code decoding unit 203, a deinterleaving unit 204, an outer code decoding unit 205, a combining unit 206, and a packet control unit 207. The second control device 20 corresponds to each process performed sequentially by the first control device 10 shown in Fig. 3 and Fig. 4, and performs processes in the order of decoding for the saving process, inner code decoding, deinterleaving, outer code decoding, and combining, to extract IP multicast packets.

[0062] The input unit 201 is an input interface for a video signal transmitted from the receiving device R, and outputs the video signal to the restoration unit 202. The restoration unit 202 performs processing to restore the inner-encoded data from the video signal that has been bit-interleaved by the saving processing on the transmitting side.

[0063] The inner code decoding unit 203 performs error correction processing based on the inner code parity bits included in the inner coded data, and generates data extracted in the scanning line direction.

[0064] The deinterleave unit 204 performs deinterleaving processing to rearrange the data extracted in the scanning line direction in a direction perpendicular to the scanning lines, and generates outer coded data arranged in the transmission order of the IP multicast packets.

[0065] The outer code decoding unit 205 performs error correction processing based on the outer code parity bits included in the deinterleaved outer coded data, and generates fixed length data that constitutes an IP multicast packet.

[0066] The combining unit 206 concatenates the decoded fixed-length data based on the synchronization pattern, and the packet control unit 207 extracts IP multicast packets based on the concatenated fixed-length data group and outputs the IP multicast packets to device D.

[0067] <Example of encapsulating IP multicast packets in video signals> As described above, the IP multicast wireless transmission system of this embodiment encapsulates IP multicast packets provided by a distribution provider, which is a data source, into a video signal format that can be transmitted using a non-IP wireless transmission method, and transmits them to the receiving side via transmitting device T.

[0068] The video signal format used for encapsulation is up to you, but you can use video signal standards such as HDMI signals and SDI signals (SD-SDI, MD-SDI). These video signals, for example, use the Transition Minimized Differential Signal (TMDS) format in the case of HDMI signals, which are divided into four areas, one of which is used as a clock storage area and the other three as data storage areas.

[0069] In other words, a video frame constituting a video signal includes areas corresponding to multiple data storage areas, and taking an HDMI signal as an example, it has three areas: "TMDS DaTa 0 (B side)," "TMDS DaTa 1 (G side)," and "TMDS DaTa 2 (R side)." In this way, a video frame in which an IP multicast packet is embedded can include multiple different data storage areas (data storage layers), and the IP multicast wireless transmission system of this embodiment utilizes each of these multiple data areas to encapsulate the IP multicast packet in a video signal.

[0070] In the following explanation, an HDMI signal is used as an example, and an example using three data areas corresponding to "TMDS DaTa 0 (B side)," "TMDS DaTa 1 (G side)," and "TMDS DaTa 2 (R side)" is described. However, this is not a limitation, and encapsulation can be performed using multiple data areas conforming to the video signal standard. Also, in the following explanation, specific byte lengths are given as examples, but this is not a limitation. The lengths of various data, such as the byte length of an IP multicast packet or a fixed byte length, are arbitrary.

[0071] Fig. 6 is a functional block diagram of the first control device 10 that encapsulates IP multicast packets into video signals corresponding to multiple data areas. Compared to the example in Fig. 2, the data control unit 101 includes an area control unit 101a. The other components are the same as those in Fig. 2 and are assigned the same reference numerals.

[0072] Figure 7 is a diagram for explaining various processes when encapsulating an IP multicast packet into a video signal corresponding to multiple data areas, and Figure 8 is a diagram for explaining the inner coding process when encapsulating an IP multicast packet into a video signal corresponding to multiple data areas.

[0073] An example of encapsulating an IP multicast packet into a 1920 x 1080 pixel video frame (frame rate: 60 fps or 30 fps, chroma subsampling: 4:4:4 or 4:2:2) will be described. First, if the IP multicast packet to be transmitted is 600 bytes long, the data control unit 101 divides it into three fixed-length data pieces with a fixed length of 212 bytes. In this example, it is divided into three fixed-length data pieces, but it may also be divided into two or four or more fixed-length data pieces. At this time, if there is any remainder in the divided fixed-length data pieces, it is filled with NULL. Next, the data control unit 101 adds a synchronization pattern (4 bytes) to each fixed-length data piece to generate 216-byte fixed-length data pieces. Up to this point, the process is the same as the fixed-length division and synchronization pattern addition shown in Figure 3.

[0074] On the other hand, the area control unit 101a sets a plurality of divided areas corresponding to the data storage area based on the format of the video signal that can be transmitted using a non-IP wireless transmission method. In the case of an HDMI signal, three data storage areas are included, so three divided areas (a first divided area (R side), a second divided area (G side), and a third divided area (B side)) are set for these three data storage areas. The data control unit 101 divides each 216-byte fixed-length data into a plurality of pieces. For example, one fixed-length data is divided in half into first-half 108-byte data and second-half 108-byte data. The data control unit 101 then assigns each of the divided byte-length data to a different divided area.

[0075] Specifically, the first half of the fixed-length data is allocated to the first division area, and the second half of the fixed-length data is allocated to the second division area. This allocation process to division areas is performed for each of the multiple fixed-length data, and the first half of the byte-length data group in each of the multiple fixed-length data is aggregated into the first division area, and the second half of the byte-length data group is aggregated into the second division area.

[0076] The outer coding unit 102 performs an outer code encoding process on each of the multiple byte-length data assigned to each divided region to generate an outer code parity bit, and then generates outer-coded data by concatenating the byte-length data and the outer code parity bit corresponding to the byte-length data. For example, the outer coding unit 102 performs an RS coding (120, 108) process on 108-byte byte-length data to generate 12 bytes of outer code parity bits, and generates 120-byte outer-coded data for each byte-length data. The outer coding unit 102 performs this process for each divided region (the outer coding process of FIG. 3 is performed for each divided region).

[0077] 3 for each divided area, rearranging the outer-coded data arranged in the transmission order of the IP multicast packets in a direction perpendicular to the scanning lines of the video signal frame (vertical direction), and assigning the outer-coded data as pixels of the video signal. In this case, nine 120-byte outer-coded data can be arranged vertically from the left edge in a 1920 x 1080 image. Any number of nine 120-byte outer-coded data arranged vertically can be arranged within a frame.

[0078] As described above, even if an entire scanning line is lost due to a burst error, only one byte is lost in the 120-byte outer coded data arranged in a direction perpendicular to the scanning lines of the frame, so that the interleaving unit 103 can properly decode the data using error correction processing based on the outer code parity bit. In the case of 120-byte outer coded data, a maximum of 54 missing scanning lines can be tolerated (effectively corrected) (((120-108)÷2)×(1080÷120)=54).

[0079] As shown in Fig. 8, the inner coding unit 104 generates a data string by extracting, in the scanning line direction, the outer-coded data rearranged in the direction perpendicular to the scanning lines for each divided region. At this time, the inner coding unit 104 concatenates data strings corresponding to each divided region and performs inner code encoding processing (LDPC: coding rate 2 / 3) on the concatenated data string group to generate an inner code parity bit. After generating the inner code parity bit, the inner coding unit 104 rearranges each data string to the corresponding divided region and assigns the generated inner code parity bit to a divided region (third divided region) other than the divided regions (first divided region and second divided region) to which byte-length data is assigned.

[0080] The saving unit 105 performs a saving process to rearrange the vertical and horizontal bit order of the data on the data string and inner code parity bits of each divided area generated by the inner coding unit 104 (the saving process shown in Figure 4 is performed for each divided area).

[0081] The output unit 106 converts each data string and the inner code parity bit after the saving process into a video signal to be transmitted in accordance with the WHDI transmission method or the WirelessHD transmission method, and outputs the signal to the transmitting device T.

[0082] Fig. 9 is a functional block diagram of the second control device 20 that supports encapsulating IP multicast packets into video signals corresponding to multiple data areas. Compared to the example in Fig. 5, a synthesis unit 206a is provided between the outer code decoding unit 205 and the combining unit 206. The other components are the same as those in Fig. 5 and are assigned the same reference numerals.

[0083] The second control device 20 corresponds to each process sequentially performed by the first control device 10 shown in Figures 7 and 8, and performs each process of decoding for the saving process, inner code decoding, deinterleaving, and outer code decoding for each of the multiple divided areas, and synthesizes the byte-length data assigned to the multiple divided areas in the synthesis unit 206a (synthesizes the multiple divided areas to which byte-length data are assigned).

[0084] The input unit 201 is an input interface for a video signal transmitted from the receiving device R, and outputs the video signal to the restoration unit 202. The restoration unit 202 performs processing to restore the video signal that has been bit-interleaved by the saving processing on the transmitting side for each divided region.

[0085] The inner code decoding unit 203 performs error correction processing based on the inner code parity bits assigned to a division area other than the division area to which the byte-length data is assigned, and generates a group of data sequences by concatenating the data sequences corresponding to each division area.

[0086] The deinterleave unit 204 assigns the inner-coded decoded data sequence to the corresponding divided area, and for each divided area, performs a deinterleave process to rearrange the data sequence cut out in the scanning line direction in a direction perpendicular to the scanning line, thereby generating the outer-coded data arranged in the transmission order of the IP multicast packet.

[0087] The outer code decoding unit 205 performs error correction processing based on the outer code parity bits included in the deinterleaved outer coded data for each divided region, and generates byte length data.

[0088] The synthesis unit 206a combines the byte-length data assigned to each segment to generate fixed-length data. The combining unit 206 concatenates the synthesized fixed-length data. The packet control unit 207 then extracts IP multicast packets based on the concatenated fixed-length data group and outputs the IP multicast packets to device D.

[0089] Although the number of data storage areas in a video frame constituting a video signal has been described in three modes using an HDMI signal as an example, byte-length data may be allocated to multiple divided areas in accordance with any video signal format (video signal standard) that can be transmitted using a non-IP wireless transmission system. In this case, one divided area is used for an inner code parity bit, so that the fixed-length data can be divided into multiple byte-length data according to the number of remaining divided areas, and each divided byte-length data can be allocated to each of the remaining divided areas. [Explanation of symbols]

[0090] 10 First control device (capsule device) 101 Data control section 101a Area control unit 102 Outer encoding section 103 Interleave section 104 Inner encoder 105 Evacuation Area 106 Output section 20 (20A, 20B, 20C) Second control device 201 Input section 202 Restoration Department 203 Inner code decoding unit 204 Deinterleave section 205 Outer code decoding unit 206a Synthesis Department 206 Joint 207 Packet control section T transmitter R receiving device Tt,Rt wireless communication section D equipment

Claims

1. An IP multicast wireless transmission system in which IP multicast packets are transmitted from a transmitting device to one or more receiving devices by one-way communication, the transmitting device and the receiving device are equipped with a wireless communication unit that uses a WHDI transmission system or a WirelessHD transmission system to transmit and receive video signals by radio waves; a first control device that encapsulates the IP multicast packet into a video signal format that can be transmitted by a WHDI transmission system or a WirelessHD transmission system and outputs the encapsulated video signal to the transmitting device; a second control device that extracts the IP multicast packets from the video signal output from the receiving device; The data is sent using an FEC method in which errors occurring on a transmission path between the sending device and the receiving device are corrected on the receiving device side, and The first control device an outer coding unit that performs an outer code coding process on each of a plurality of fixed-length data generated by dividing the IP multicast packet into byte data of a predetermined fixed length to generate an outer code parity bit, and generates outer-coded data by concatenating the fixed-length data and the outer code parity bit corresponding to the fixed-length data; an interleaving unit that rearranges each of the outer-coded data arranged in the transmission order of the IP multicast packets in a direction perpendicular to a scanning line of a frame of a video signal, and performs interleaving to assign the outer-coded data as pixels of the video signal; an inner coding unit that extracts the outer coded data rearranged in a direction perpendicular to the scanning lines in the scanning line direction, performs an inner code encoding process on the extracted data to generate an inner code parity bit, and adds the inner code parity bit to the extracted data to generate inner coded data; an output unit that converts the inner-encoded data into a video signal that can be transmitted by a WHDI transmission system or a Wireless HD transmission system and outputs the video signal to the transmitting device; An IP multicast wireless transmission system comprising:

2. The first control device a data control unit that divides the IP multicast packet into byte data of a predetermined fixed length to generate a plurality of fixed-length data, and adds a synchronization pattern indicating a delimiter of the IP multicast packet to each fixed-length data; the outer coding unit performs an outer code coding process on each fixed-length data to which a synchronization pattern has been added to generate an outer-code parity bit, and generates the outer-coded data by concatenating the fixed-length data to which the synchronization pattern has been added and the outer-code parity bit corresponding to the fixed-length data to which the synchronization pattern has been added; a saving unit that performs a saving process of switching the order of vertical and horizontal bits of the inner-coded data; the output unit converts the data sequence after the saving process into a video signal to be transmitted by a WHDI transmission method or a Wireless HD transmission method, and outputs the video signal to the transmission device.

2. The IP multicast wireless transmission system according to claim 1, wherein:

3. The second control device is an inner code decoding unit that performs error correction processing based on the inner code parity bit included in the inner coded data and generates data extracted in the scanning line direction; a deinterleave unit that performs a deinterleave process to rearrange the data cut out in the scanning line direction in a direction perpendicular to the scanning line, and generates the outer coded data arranged in the transmission order of the IP multicast packets; an outer code decoding unit that performs error correction processing based on an outer code parity bit included in the outer coded data after deinterleaving, and generates fixed length data that constitutes the IP multicast packet; a concatenation unit that concatenates the decoded fixed-length data; a packet control unit that extracts the IP multicast packet based on the linked fixed-length data group; 2. The IP multicast wireless transmission system according to claim 1, comprising:

4. An IP multicast wireless transmission system that transmits IP multicast packets from a transmitting device to one or more receiving devices by unidirectional communication, comprising: the transmitting device and the receiving device are equipped with a wireless communication unit that uses a WHDI transmission system or a WirelessHD transmission system to transmit and receive video signals by radio waves; a first control device that encapsulates the IP multicast packet into a video signal format that can be transmitted by a WHDI transmission system or a WirelessHD transmission system and outputs the encapsulated video signal to the transmitting device; a second control device that extracts the IP multicast packets from the video signal output from the receiving device; The data is sent using an FEC method in which errors occurring on a transmission path between the sending device and the receiving device are corrected on the receiving device side, and The first control device a data control unit that divides each of a plurality of fixed-length data pieces generated by dividing the IP multicast packet into byte data pieces of predetermined fixed length, and allocates each of the plurality of divided byte-length data pieces to a different divided area; an outer coding unit that performs outer coding processing on each divided area to which byte-length data is assigned, the outer coding processing being to perform outer code coding processing on byte-length data to generate outer code parity bits, and to generate outer coded data by concatenating the byte-length data and the outer code parity bits corresponding to the byte-length data; an interleaving unit that performs interleaving by rearranging the outer-coded data arranged in the transmission order of the IP multicast packets for each divided area in a direction perpendicular to a scanning line of a frame of a video signal, and assigning the outer-coded data as pixels of the video signal; an inner coding unit that generates a data string by extracting the outer coded data, rearranged in a direction perpendicular to the scanning lines, for each divided area in the scanning line direction, and performs an inner code coding process on a data string group formed by concatenating data strings corresponding to each of the plurality of divided areas to generate an inner code parity bit, and assigns the generated inner code parity bit to a divided area other than the divided area to which byte length data is assigned; an output unit that converts each data string generated for each divided area and the inner code parity bit into a video signal to be transmitted by a WHDI transmission system or a Wireless HD transmission system and outputs the video signal to the transmitting device; An IP multicast wireless transmission system comprising:

5. the data control unit divides the IP multicast packet into byte data of a predetermined fixed length to generate a plurality of fixed-length data, adds a synchronization pattern indicating a delimiter of the IP multicast packet to each fixed-length data, divides the fixed-length data to which the synchronization pattern has been added into a plurality of byte-length data, and assigns each of the divided byte-length data to a different divided area; the first control device further includes a saving unit that performs a saving process of switching the order of vertical and horizontal bits of data on the data string of each divided area generated by the inner coding unit and the inner code parity bits of another divided area; the output unit converts each data string after the saving process and the inner code parity bit into a video signal to be transmitted by a WHDI transmission system or a Wireless HD transmission system, and outputs the video signal to the transmitting device.

5. The IP multicast wireless transmission system according to claim 4.

6. The second control device is an inner code decoding unit that performs error correction processing based on the inner code parity bits assigned to other divided areas and generates a data sequence group by concatenating data sequences corresponding to each of the plurality of divided areas; a deinterleaving unit that allocates the inner-coded decoded data strings to corresponding divided regions, performs a deinterleaving process for each divided region to rearrange the data strings cut out in the scanning line direction in a direction perpendicular to the scanning line, and generates the outer-coded data arranged in the transmission order of the IP multicast packets; an outer code decoding unit that performs error correction processing based on an outer code parity bit included in the deinterleaved outer coded data for each divided region, and generates byte length data; a synthesis unit that synthesizes the corresponding byte-length data allocated to each divided area and generates fixed-length data; a combining unit that combines the synthesized fixed-length data; a packet control unit that extracts the IP multicast packet based on the linked fixed-length data group; 5. The IP multicast wireless transmission system according to claim 4, comprising:

7. 1. An encapsulation device that receives an IP multicast packet provided from a data source and encapsulates the IP multicast packet into a video signal format that can be transmitted by a WHDI transmission method or a Wireless HD transmission method, an outer coding unit that performs an outer code coding process on each of a plurality of fixed-length data generated by dividing the IP multicast packet into byte data of a predetermined fixed length to generate an outer code parity bit, and generates outer-coded data by concatenating the fixed-length data and the outer code parity bit corresponding to the fixed-length data; an interleaving unit that rearranges each of the outer-coded data arranged in the transmission order of the IP multicast packets in a direction perpendicular to a scanning line of a frame of a video signal, and performs interleaving to assign the outer-coded data as pixels of the video signal; an inner coding unit that extracts the outer coded data rearranged in a direction perpendicular to the scanning lines in the scanning line direction, performs an inner code encoding process on the extracted data to generate an inner code parity bit, and adds the inner code parity bit to the extracted data to generate inner coded data; an output unit that converts the inner encoded data into a video signal that can be transmitted by a WHDI transmission system or a Wireless HD transmission system and outputs the video signal; A capsule device comprising:

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