JP2014146937A - Transmission processing device, retransmission system, and transmission processing method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission processing device, a retransmission system, and a transmission processing method and program capable of correctly detecting a transmission error even when rate conversion is performed in the middle of a transmission line.SOLUTION: Provided is a transmission processing device (101) for processing a TS signal including a null packet and a first PCR packet and to be transmitted to a reception processing device, wherein the transmission processing device (101) comprises a first conversion unit (124) for converting a null packet into a dummy packet having a PID different from the null packet, a second conversion unit (124) for differentiating a PID at destination of time-of-day information acquisition in the TS signal from the PID of a first PCR packet, a generation unit (133) having time-of-day information synchronized to the first PCR packet and used for generating a second PCR packet having the PID at destination of time-of-day information acquisition, and a synthesis unit (137) for synthesizing the TS signal having had processing by first and second modification units (123, 124) applied thereto and the second PCR packet.

Description

  The present invention relates to a transmission processing apparatus, a retransmission system, a transmission processing method, and a program.

  2. Description of the Related Art Conventionally, a relay system for relaying a sports event or a disaster situation from a spot (a newsroom or a news car) is known. In this relay system, a radio transmission device (FPU: Field Pick-up Unit) mounted on a relay vehicle transmits a video signal captured by a video camera to a broadcast studio (hereinafter abbreviated as a studio) by radio, A broadcast studio broadcasts this video signal to the public. However, wireless communication is easily affected by the communication environment such as weather conditions and geographical conditions, and the video may be disturbed. In this case, the person on the studio side (reception side) contacts the person on the FPU side (transmission side) with a mobile phone and requests retransmission of the disturbed video. A person on the FPU side specifies a retransmission point by rewinding a VTR (Video Tape Recorder) or the like, but this work is troublesome, and in an emergency, broadcasting may not be in time.

  When signals are transmitted using IP (Internet Protocol) communication such as the Internet instead of such wireless communication, there is a method of automatically retransmitting (ARQ = Automatic Repeat reQuest: automatic repeat request, for example, non-transmission request) Patent Document 1). On the transmission side, one transmission block is composed of one or a plurality of TS packets, and a sequence number for distinguishing from other blocks is assigned to each block. The transmission side stores the transmission block data and sequence number in the payload portion of the IP packet and transmits it. On the receiving side, the sequence of sequence numbers stored in the payload of the arrived IP packet is confirmed, and if there is a block that has not arrived, a retransmission request is sent to the transmitting side. In IP communication, since the payload portion is not rewritten by a router or HUB in the middle of the transmission path, the receiving side only needs to confirm whether or not a block is lost.

“ARIB TR-B34 Production and Coverage Guidelines for Ensuring Quality in Real-time IP Video Transmission”, formulated on December 6, 2011

  Here, let us consider a case where a TS (Transport Stream) signal in digital broadcasting is transmitted as a DVB-ASI (Digital Video Broadcasting-Asynchronous Serial Interface) signal instead of being transmitted as an IP packet. When the transmission side and the reception side are separated, signals are transmitted using FPU and CS (communication satellite). At this time, the modulator on the transmission side may insert a null packet into the signal so that the bit rate on the transmission side becomes a predetermined bit rate determined by the radio modulation scheme at the time of FPU or CS transmission (rate Called conversion). At this time, the modulator on the transmitting side corrects the time information by rewriting the PCR packet because an error occurs in the time information indicated by the PCR packet only by inserting the null packet. That is, since a device that relays the signal is interposed between the transmission side and the reception side and rewrites the signal, it is detected that there is a transmission error even if there is no problem in the transmission path. A transmission error cannot be detected only by confirming the loss of a signal as in the case of IP communication.

  Accordingly, an object of the present invention made in view of the above problems is to provide a transmission processing device, a retransmission system, a transmission processing method, and a program capable of correctly detecting a transmission error even if rate conversion is performed in the middle of a transmission path. It is to provide.

In order to solve the above-described problems, the invention of the transmission processing device according to the first aspect is as follows:
In a transmission processing device that processes a TS signal to be transmitted to a reception processing device and includes a null packet and a first PCR packet,
A first changing unit that converts the null packet into a dummy packet having a packet identifier different from the null packet;
A second changing unit that makes the packet identifier of the time information acquisition destination in the TS signal different from the packet identifier of the first PCR packet;
A generating unit that generates time information synchronized with the first PCR packet and generates a second PCR packet having the packet identifier of the time information acquisition destination;
It is a transmission processing apparatus provided with the synthetic | combination part which synthesize | combines the said TS signal with which the process of the said 1st and 2nd change part was performed, and the said 2nd PCR packet.

The invention according to the second aspect is the transmission processing device according to the first aspect,
A calculation unit for calculating an error detection code for detecting a transmission error of the TS signal subjected to the processing of the first and second changing units;
An acquisition unit that acquires a retransmission request for a signal that was not correctly acquired in the reception processing device;
The acquisition unit further includes a third changing unit that makes a packet identifier of the TS signal by retransmission out of the TS signal subjected to the processing of the first and second changing units different from the TS signal by initial transmission. Gets a resend request,
The synthesizer synthesizes the TS signal by the retransmission, the TS signal by the initial transmission, and the second PCR packet.

In order to solve the above-described problems, the retransmission system according to the third aspect
In a retransmission system including a transmission processing device that processes a TS signal to be transmitted to a reception processing device and includes a null packet and a first PCR packet, and the reception processing device that acquires the TS signal,
The transmission processing device includes:
a. converting the null packet into a dummy packet having a packet identifier different from the null packet;
b. making the packet identifier of the time information acquisition destination in the TS signal different from the packet identifier of the first PCR packet;
c. generating a second PCR packet having time information synchronized with the first PCR packet and having the packet identifier of the time information acquisition destination;
d. combining the TS signal subjected to the processing a. and b. and the second PCR packet;
The reception processing device includes:
In the retransmission system, a retransmission request for a signal that has not been correctly acquired is transmitted to the transmission processing device.

An invention according to a fourth aspect is the retransmission system according to the third aspect.
The reception processing device includes:
Storing the acquired TS signal;
Send the stored TS signal at a predetermined timing,
Obtain the remaining time for which a retransmission request is possible from the predetermined timing,
The retransmission request interval of the retransmission request is determined based on the remaining time.

  The invention according to a fifth aspect is the retransmission system according to the fourth aspect, wherein when the remaining time becomes less than a predetermined time, the reception processing device requests a retransmission more than when the remaining time is equal to or longer than the predetermined time. The interval is narrowed.

  As described above, the solution of the present invention has been described as an apparatus. However, the present invention can be realized as a method, a program, and a storage medium storing the program, which are substantially equivalent thereto, and the scope of the present invention. It should be understood that these are also included.

For example, a transmission processing method according to a sixth aspect that realizes the present invention as a method includes:
In a transmission processing method in which a transmission processing device processes a TS signal to be transmitted to a reception processing device and includes a null packet and a first PCR packet.
converting the null packet into a dummy packet having a packet identifier different from the null packet;
b. differentiating the packet identifier of the time information acquisition destination in the TS signal from the packet identifier of the first PCR packet;
c. generating a second PCR packet having time information synchronized with the first PCR packet and having the packet identifier of the time information acquisition destination;
d. A transmission processing method including the step of combining the TS signal subjected to steps a. and b. and the second PCR packet.

A program according to the seventh aspect of the present invention realized as a program is
A TS signal to be transmitted to the reception processing device, and a computer constituting the transmission processing device that processes the TS signal including the null packet and the first PCR packet,
converting the null packet into a dummy packet having a packet identifier different from the null packet;
b. differentiating the packet identifier of the time information acquisition destination in the TS signal from the packet identifier of the first PCR packet;
c. generating a second PCR packet having time information synchronized with the first PCR packet and having the packet identifier of the time information acquisition destination;
d. A program for executing the step of synthesizing the TS signal subjected to steps a. and b. and the second PCR packet.

  According to the transmission processing device, the retransmission system, the transmission processing method, and the program according to the present invention configured as described above, rate conversion is performed in the middle of the transmission path, and null packets are inserted and PCR is rewritten. Transmission errors can also be detected on the transmission line.

FIG. 1 is a schematic configuration diagram of a retransmission system according to an embodiment of the present invention. FIG. 2 is a functional block diagram showing a schematic configuration of the transmission processing apparatus according to the embodiment of the present invention. FIG. 3 is an explanatory diagram showing blocks and block data according to an embodiment of the present invention. FIG. 4 is a functional block diagram showing a schematic configuration of a reception processing apparatus according to an embodiment of the present invention.

  Hereinafter, a retransmission system according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a retransmission system according to an embodiment of the present invention. The retransmission system 100 includes a transmission processing device 101, a transmitter 103, a receiver 105, and a reception processing device 107.

  The transmission processing apparatus 101 performs signal processing (for example, processing described in the description of FIG. 2) on the input original TS signal, and transmits the processed TS signal (referred to as a transmission TS signal) to the transmitter 103. It is the device which outputs to. The TS signal is a signal in a format defined by ISO / IEC-13818 MPEG2 Systems. The original TS signal is a signal to be transmitted to the reception processing device 107 via the transmitter 103 and the receiver 105, and is a null packet (first null packet) and a PCR (Program Clock Reference) packet (first PCR packet). Is included. The transmitter 103 wirelessly transmits the transmission TS signal generated by the transmission processing device 101 to the receiver 105 via an antenna. For example, a television such as an FPU (wireless transmission device) or CS (communication satellite) is used. It is a relay device for John broadcasting. The transmitter 103 can use any radio modulation scheme.

  The receiver 105 receives a signal wirelessly transmitted from the transmitter 103, and includes, for example, an antenna installed in a broadcasting station. The reception processing device 107 is a device that performs signal processing (for example, processing described in the description of FIG. 4) on the transmission TS signal from the receiver 105, restores the original TS signal, and outputs it. In addition, the reception processing device 107 determines whether or not the transmission TS signal has been correctly received. If the reception processing device 107 has not received the transmission TS signal correctly, the reception processing device 107 transmits a retransmission request to the transmission processing device 101. The transmission of the retransmission request is realized by a communication connection different from the transmission TS signal transmission by the transmitter 103. Unlike the TS transmission path between the transmitter 103 and the receiver 105, the communication connection for the retransmission request merely transmits a short message for the retransmission request and does not transmit the TS signal. The band may be narrow. For example, the transmission processing device 101 and the reception processing device 107 are each connected to a mobile phone terminal via the RS232C, and realized by using a wireless communication connection between the mobile phone terminals. Cost reduction can be achieved by using an existing mobile phone terminal for the retransmission request communication connection.

  FIG. 2 is a functional block diagram showing a schematic configuration of the transmission processing apparatus according to the embodiment of the present invention. The transmission processing apparatus 101 of the present embodiment includes a PCR lock unit 121, a first PID change unit (first change unit) 123, a second PID change unit (second change unit) 124, a control data calculation unit (calculation unit) 125, A preprocessing unit including a 1MUX unit 127, an acquisition unit 128, a transmission side reading unit 129, a transmission side storage unit 130, a storage / reproduction unit including a retransmission PID change unit (third change unit) 131, and a PCR packet unit (generation unit) 133, and a remultiplexing unit including a second MUX unit (combining unit) 137.

  The PCR lock unit 121 generates time information synchronized with the PCR packet of the input original TS signal. The generated time information is used in the PCR packet unit 133 described later. The original TS signal is also input to the first PID changing unit 123.

  The first PID changing unit 123 converts the null packet included in the original TS signal into a dummy packet having a PID (Packet Identifier) different from the null packet. For example, in the TS packet in MPEG-2, the PID of the null packet is defined as 8191 (0x1FFF), and therefore the first PID changing unit 123 rewrites the PID of the null packet to a value other than 8191. Then, the first PID changing unit 123 describes the PID of the dummy packet in the PMT so that the receiving side can specify the PID of the dummy packet. The first PID changing unit 123 sends a TS signal including a dummy packet to the second PID changing unit 124.

  The second PID changing unit 124 makes the time information acquisition destination PID in the original TS signal different from the PID of the PCR packet in the TS signal. In the PMT (Program Map Table) included in the original TS signal, the PID of the PCR packet of the original TS signal is described in advance as the PID of the PCR packet (time information acquisition destination) to be referred to. 124 rewrites this PID to a value not used in the original TS signal (referred to as alternative PCR-PID). Then, the second PID changing unit 124 notifies the PCR packet unit 133 of the rewritten value. The second PID changing unit 124 does not change the PCR packet itself (time information) of the original TS signal. Then, the second PID changing unit 124 describes the information of the PID of the PCR packet in the original TS signal (referred to as original PCR-PID) in the PMT separately from the PID of the PCR packet to be referred to, and the receiving side makes the original PCR -Enable PID identification. The second PID changing unit 124 sends the TS signal after the PID change to the first MUX unit 127 and the control data calculating unit 125.

  By the processing of the first PID changing unit 123 and the second PID changing unit 124, the null packet and the PCR packet included in the original TS signal are preserved as separate packets that do not play the role of the null packet or the PCR packet, respectively. Become.

  The control data calculation unit 125 divides the input TS signal into a predetermined number (hereinafter referred to as “n”) of continuous TS packet aggregates (block data), and each block uniquely identifies the sequence number. (Referred to as block number). Furthermore, the control data calculation unit 125 calculates an error detection code for detecting a transmission error, and generates a control packet (referred to as a CTL packet) having the code. For example, the control data calculation unit 125 calculates a CRC (Cyclic Redundancy Check) value for each block data, and outputs a CTL packet including the CRC value information and the block number information to the first MUX unit 127. To do. The PID of the CTL packet is an arbitrary value that does not overlap with other packets, and the information is notified to the first MUX unit 127. Note that the number (n) of TS packets included in the block data is an arbitrarily set item. The error detection code is not limited to CRC, and a known error detection technique such as a parity code can be applied. Further, in the present embodiment, it is assumed that a smaller block number is assigned to block data to be transmitted earlier in time from the transmitter 103.

  The first MUX unit 127 describes the PID information of the CTL packet notified from the control data calculation unit 125 in the PMT. Further, the first MUX unit 127 combines the TS signal after the PID change and the CTL packet. Specifically, the first MUX unit 127 inserts each CTL packet after the last TS packet of the corresponding block data as shown in FIG. In FIG. 3, TS1-1 means the first TS packet of the first block data, and CTL1 means a CTL packet corresponding to the first block data. Hereinafter, one block data and a corresponding CTL packet are collectively referred to as a block. In particular, in order to distinguish from a retransmission block (described later), a block output by the first MUX unit 127 is referred to as an initial transmission block. Since the CTL packet is arranged at the end of each block, the end of the block can be specified by detecting the CTL packet. Then, the first MUX unit 127 sends the combined TS signal (initial transmission block) to the second MUX unit 137 and stores it in the storage area divided for each block number of the transmission side storage unit 130.

  The acquisition unit 128 acquires a signal (command) indicating a retransmission request for a block that cannot be correctly transmitted from the reception processing device 107, and is, for example, an RS232C interface. The retransmission request includes a block number for specifying a block that the reception processing device 107 could not correctly acquire. When acquiring the retransmission request, the acquiring unit 128 sends the retransmission request to the transmitting side reading unit 129.

  The transmission side reading unit 129 reads the block having the block number requested for retransmission from the transmission side storage unit 130 and sends the block to the retransmission PID change unit 131. Hereinafter, a block read from the transmission-side storage unit 130 under the control of the transmission-side reading unit 129 is referred to as a retransmission block.

  The retransmission PID changing unit 131 changes the PID of the TS packet included in the retransmission block (hereinafter also referred to as PID 'as appropriate) to an arbitrary value that is different from the original PID and does not overlap with other TS packets. For example, the retransmission PID changing unit 131 sets the PID ′ used in the TS packet of the retransmission block to a value that is one larger than that used in the TS packet of the corresponding initial transmission block, and the value is the value of the initial transmission block or other If it overlaps with the one used in the retransmission block, one more is added to search for a non-overlapping PID. More specifically, when the three TS packets in the initial transmission block use PID = {1,3,4}, the retransmission PID changing unit 131 uses the PID in the retransmission block of the TS packet with PID = 1. Let 'be PID with 1 added' = 2. Further, the retransmission PID changing unit 131 sets PID ′ in the retransmission block of the TS packet with PID = 3 to 1 by adding PID ′ = 5, since 4 plus 1 is already in use in the initial transmission block. Further, the retransmission PID changing unit 131 sets PID ′ in the retransmission block of the TS packet with PID = 4 to 1 by adding PID ′ = 6 since 5 plus 1 is already in use in the retransmission block. As a result, the PID ′ used in the retransmission block is PID ′ = {2, 5, 6}, and the retransmission PID changing unit 131 can determine a PID ′ that does not overlap with the initial transmission block. Then, the retransmission PID changing unit 131 sends the retransmission block to the second MUX unit 137. In addition, the retransmission PID changing unit 131 notifies the second MUX unit 137 of information on how the PID of the initial transmission block is changed in the retransmission block.

  The PCR packet unit 133 sends a PCR packet (second PCR packet) synchronized with the time information generated by the PCR lock unit 121 (that is, the time information of the first PCR packet in the TS signal) to the second MUX unit 137. The PID of the PCR packet is the alternative PCR-PID (PID of the time information acquisition destination) notified from the second PID changing unit 124. The PMT describes an alternative PCR-PID as the PID of the PCR packet to be referred to. Therefore, as described in the description of the second PID changing unit 124, the PCR of the original TS signal is preserved as a separate packet that is not a PCR, and the one generated by the PCR packet unit 133 plays the role of the PCR. Become.

  The second MUX unit 137 describes the information of PID ′ used in the retransmission block notified from the retransmission PID changing unit 131 in the PMT. Further, the second MUX unit 137 generates a transmission TS signal by combining the initial transmission block (TS signal by initial transmission), the PCR packet, and the retransmission block (TS signal by retransmission) when there is a retransmission request. To the transmitter 103. When the input to the transmitter 103 must be a constant bit rate, the second MUX unit 137 inserts a null packet (second null packet) until the desired bit rate is reached, and the PCR packet ( The time information indicated by the one generated by the PCR packet unit 133 may be corrected.

  The transmission TS signal is transmitted from the transmitter 103 to the receiver 105 wirelessly. At that time, the transmitter 103 may perform rate conversion by inserting a null packet and correcting a PCR (second PCR packet) in order to obtain a bit rate according to a radio modulation scheme to be used.

  The transmission-side storage unit 130 stores various information such as a program describing the processing contents for realizing each function of the transmission processing device 101 and the above-mentioned initial transmission block. For example, a RAM (Random Access Memory) or the like is stored. A volatile storage medium or a non-volatile storage medium such as a ROM (Read Only Memory).

  Note that a computer can be suitably used to function as the transmission processing apparatus 101 described above, and the CPU of such a computer executes the transmission process by executing the program stored in the transmission-side storage unit 130. Each function of the apparatus 101 can be realized.

  FIG. 4 is a functional block diagram showing a schematic configuration of a reception processing apparatus according to an embodiment of the present invention. The reception processing device 107 of this embodiment includes a separation unit including a PCR lock unit 151 and a filter unit 153, an initial transmission block determination unit 155, a retransmission PID restoration unit 157, a retransmission block determination unit 159, a retransmission request unit 167, and a transmission unit. And a post-processing unit including a PID restoration unit 161, a reception-side storage unit 162, and a reception-side reading unit 163.

  The transmission TS signal transmitted from the transmitter 103 and received by the receiver 105 is sent to the PCR lock unit 151 of the reception processing device 107. The PCR lock unit 151 generates time information synchronized with the PCR of the input transmission TS signal. The generated time information is used by the receiving side reading unit 163 described later. The transmission TS signal is also input to the filter unit 153.

  The filter unit 153 deletes the PCR packet (second PCR packet) and the null packet (second null packet) included in the transmission TS signal. In addition, the filter unit 153 recognizes the PIDs of the initial transmission block and the retransmission block from the PMT information included in the transmission TS signal, and separates the initial transmission block and the retransmission block. Then, the filter unit 153 sends the initial transmission block to the initial transmission block determination unit 155 and sends the retransmission block to the retransmission PID restoration unit 157.

  The initial transmission block determination unit 155 calculates the CRC value of the block data for each initial transmission block, and determines whether or not there is a transmission error in the block from comparison with the CRC value included in the CTL packet of the block. When there is no transmission error in the initial transmission block, the initial transmission block determination unit 155 transmits the block to the PID restoration unit 161. If there is a transmission error, the initial transmission block determination unit 155 discards the block.

  The retransmission PID restoration unit 157 returns the PID after changing the retransmission block to the PID before the change. Information on how the retransmission PID changing unit 131 of the transmission processing apparatus 101 has changed the PID can be grasped by referring to the PMT of the transmission TS signal.

  The retransmission block determination unit 159 calculates a CRC value of the block data for each retransmission block, and determines whether a transmission error exists in the block from comparison with the CRC value included in the CTL packet of the block. If there is no transmission error in the retransmission block, retransmission block determination section 159 sends the block to PID restoration section 161. If there is a transmission error, retransmission block determination section 159 discards the block.

  The PID restoration unit 161 extracts block number information from the CTL packet of the initial transmission block and the retransmission block, deletes the CTL packet, and extracts block data. Then, the PID restoration unit 161 refers to the PMT, grasps the PID of the dummy packet, and changes the PID of the packet having the PID (dummy packet) to 0x1fff (a value indicating a null packet). Further, the PID restoration unit 161 rewrites the PID of the PCR packet to be referred to in the PMT so that the original PCR-PID packet described in the PMT is referred to as the PCR.

  As a result, the null packet of the original TS signal that has been preserved as a dummy packet is restored, and the PCR packet of the original TS signal is referred to. Then, the PID restoration unit 161 stores the processed block data in a storage area divided for each block number in the reception-side storage unit 162.

  In the PID restoration unit 161, the PID information of the dummy packet (described by the first PID changing unit 123) described in the PMT and the PID information used in the retransmission block (from the retransmission PID changing unit 131). The information described by the second MUX unit 137 may be deleted based on the notification. By this erasure, the TS signal stored in the reception-side storage unit 162 by the PID restoration unit 161 becomes completely the same as the original TS signal. Since these pieces of information are meaningful only for the reception processing device 107, there is no problem if erasure is not performed.

  Based on the time information generated by the PCR lock unit 151, the reception side reading unit 163 reads out and outputs block data from the reception side storage unit 162 in the order of block numbers at a predetermined timing. The read block data is erased from the receiving-side storage unit 162.

  The predetermined timing is a timing at which the time information indicated by the PCR included in the TS signal output from the receiving side reading unit 163 maintains a state delayed by a certain time from the time information generated by the PCR lock unit 151. is there. The receiving side reading unit 163 reads the block data with a delay, and makes a retransmission request for the block that was not correctly transmitted during that time to correct the transmission error. The degree of delay in reading may be arbitrarily determined according to the storage capacity of the receiving-side storage unit 162 and the use of this system.

  The retransmission request unit 167 monitors the storage state of the reception-side storage unit 162 at regular time intervals, and block data that is not yet stored in the reception-side storage unit 162 because it cannot be transmitted correctly (referred to as unstored block data). When a signal is detected, a retransmission request signal (command) including a block number of a block (referred to as an unstored block) corresponding to the block data is generated. Then, retransmission request section 167 controls sending section 169 to transmit a retransmission request.

  The bandwidth that can be transmitted on the transmission path between the transmitter 103 and the receiver 105 is limited, and only the bandwidth excluding the bit rate of the original TS signal and the bandwidth of control signals such as CTL packets can be used for retransmission. Therefore, even when a large number of unstored blocks are found, the retransmission request unit 167 performs only a certain number of retransmission requests based on a determination method described later. The maximum number that can be requested for retransmission can be calculated by the following equation (1), and is set in the retransmission request unit 167 in advance.

Maximum number of retransmission requests = Bandwidth available for retransmission [bps] x Monitoring interval [seconds] / Block size [bit] (1)

  A method for determining which block is to be preferentially requested for retransmission when the retransmission request unit 167 finds a large number of unstored blocks will be described.

  First, the remaining retransmission request time is calculated for each unstored block. The retransmission request remaining time means that before retransmission of the TS packet of each block data from the reception-side storage unit 162, the retransmission request must be made before the retransmission is completed and stored in the reception-side storage unit 162. Is the remaining time. When this embodiment is applied to an actual machine, processing time in each device and signal transmission time between devices occur. Therefore, after the retransmission request unit 167 makes a retransmission request, the retransmission block is received on the receiving side. A delay time D occurs until the data is stored in the storage unit 162. Specifically, the processing time from when the retransmission request unit 167 performs retransmission until the transmission unit 169 transmits the retransmission request and the transmission until the retransmission request reaches the acquisition unit 128 of the transmission processing apparatus 101 from the transmission unit 169 Time, processing time from when the acquisition unit 128 acquires the retransmission request until the transmitter 103 transmits the retransmission block (when there are a plurality of retransmission blocks, the time until all are transmitted), and the retransmission block This is the sum of the transmission time from the transmitter 103 to the receiver 105 and the processing time from when the receiver 105 receives the retransmission block until the reception-side storage unit 162 stores the retransmission block.

  The retransmission request remaining time R in consideration of the delay time D can be obtained by the following equation (2).

  R = (y−x) / LD (2)

  y is a block number of unstored block data, and x (y> x) is a block number of block data to be read next from the receiving-side storage unit 162. L is the number of block data transmitted from the reception-side storage unit 162 per unit time by reading at a predetermined timing by the reception-side reading unit 163. Therefore, (y−x) / L represents the remaining time until unstored block data is read, and at least a delay time needs to be secured in order to make a retransmission request. It is expressed by equation (2). Therefore, if a retransmission request is made while the retransmission request remaining time is 0 or more, the block data of the retransmission block reaches the reception side storage unit 162 before the timing at which the block data is read.

  Next, a timer is provided in the retransmission request unit 167 for each unstored block. This timer loads a predetermined value (described later) as an initial value every time a retransmission request is made. The timer value is subtracted with the passage of time, and when it reaches 0, it times out. For an unstored block that has never been requested to be retransmitted, 0 is loaded as an initial value, and a timeout is set from the beginning.

  The initial value T loaded to the timer of the unstored block requested for retransmission can be obtained by the following equation (3) using the remaining retransmission request time R. In Equation (3), k is a coefficient that determines the retransmission request interval.

  The retransmission request unit 167 gives priority to the block with the smallest timer value among the timers provided for each unstored block, and gives priority to the block with the shortest retransmission request remaining time for blocks with the same timer value. Request retransmission from high unstored block. When the maximum number that can be requested for retransmission has been reached, no further retransmission requests are made.

  Here, how the retransmission request pattern changes depending on the setting of the coefficient k will be described.

  When k = 0, the value loaded in the timer is always the delay time D, and a pattern for making the next retransmission request after confirming the failure of the previous retransmission request is obtained. Duplicate retransmission requests for specific unstored blocks are not made, and instead, retransmission requests for other unstored blocks can be made.

  When k = ∞, the value loaded in the timer is always 0, and the priority of the unstored block for which retransmission is requested is determined only by the remaining retransmission request time. Without confirming the success / failure of the previous retransmission request, the pattern is such that a retransmission request is repeatedly made preferentially from the block that is being read by the receiving side reading unit 163. Since a retransmission request is made redundantly for an unstored block that has already been requested for retransmission, the possibility that the unstored block will be retransmitted many times and transmitted without error increases.

  In the case of 0 <k <∞, the above intermediate pattern is obtained. When there is an unstored block with a short retransmission request remaining time, as in the case of k = ∞, the retransmission request is repeatedly made without confirming success or failure, and other unstored blocks (retransmission request remaining Re-sending requests that are long) will be delayed. When there is no unstored block with a short retransmission request remaining time, a pattern for requesting the next retransmission is made after confirming the failure of the previous retransmission request in the same manner as k = 0. Re-transmission requests are made equally to many unstored blocks. Whether or not the retransmission request remaining time is short is determined based on whether R <kD in the above equation (3). That is, if the retransmission request remaining time R is less than kD, it is determined that the retransmission request remaining time is short.

  Since the optimum coefficient k varies depending on the transmission error characteristics (error rate and burst property) of the transmission line to be used, the optimum value is determined experimentally and set in the reception processing device 107.

  The sending unit 169 sends a signal indicating a request for retransmission of an unstored block in the transmission TS signal to the transmission processing apparatus 101 (acquisition unit 128), and is, for example, an RS232C interface.

  The reception-side storage unit 162 stores various information such as a program describing the processing contents for realizing each function of the reception processing device 107 and the above-described block data. For example, a volatile storage such as a RAM (Random Access Memory) Or a non-volatile storage medium such as a ROM (Read Only Memory).

  Note that a computer can be suitably used to function as the above-described reception processing device 107, and the CPU of such a computer executes the above-described program stored in the reception-side storage unit 162, thereby receiving processing. Each function of the device 107 can be realized.

  As described above, in the present embodiment, the first PID changing unit 123 of the transmission processing apparatus 101 converts the null packet (first null packet) of the original TS signal into a dummy packet having a packet identifier different from the null packet. The second PID changing unit 124 makes the packet identifier of the time information acquisition destination in the original TS signal different from the packet identifier of the PCR packet (first PCR packet) of the original TS signal. The PCR packet unit 133 has time information synchronized with the first PCR packet, generates a PCR packet (second PCR packet) having a packet identifier of the time information acquisition destination, and the second MUX unit 137 The TS signal subjected to the processing of the 2PID changing unit and the second PCR packet are combined and a transmission TS signal is output. Thereby, the null packet and the PCR packet of the original TS signal are recognized as different packets that do not play the role of the null packet or the PCR packet due to the change of the PID. Therefore, even if a new null packet (second null packet) is inserted by rate conversion in the transmission path, the reception processing device 107 can distinguish the first null packet of the original TS signal from the second null packet. Further, even if the PCR is rewritten (corrected) by rate conversion in the transmission path, the correction target is the second PCR packet. Therefore, the reception processing device 107 obtains the original time information from the PCR packet of the original TS signal. You can get it. Therefore, it is possible to detect a transmission error even in a TS transmission line where a null packet is inserted or a PCR is rewritten.

  In the present embodiment, the control data calculation unit 125 of the transmission processing apparatus 101 can calculate an error detection code for detecting a transmission error of the TS signal subjected to the processing of the first and second PID changing units. The acquisition unit 128 can acquire a retransmission request for a signal that has not been correctly acquired by the reception processing device 107. In addition, the retransmission PID change unit 131 can make the PID of the retransmission block different from the initial transmission block in the TS signals subjected to the processing of the first and second PID change units. The second MUX unit 137 can combine the retransmission block, the initial transmission block, and the second PCR packet when the acquisition unit 128 acquires the retransmission request. As a result, transmission of a retransmission block capable of detecting a transmission error is realized even in a TS transmission path in which null packet insertion and PCR rewriting are performed. Further, since the PIDs of the retransmission block and the initial transmission block are different, the reception processing device 107 can specify whether the received block is the initial transmission or the retransmission.

  Further, in this embodiment, the retransmission request unit 167 of the reception processing device 107 has a remaining time for which a retransmission request can be made (retransmission request based on a predetermined timing at which the reception side reading unit 163 reads block data from the reception side storage unit 162. Remaining time) can be determined. Accordingly, the retransmission request unit 167 can make a retransmission request so that the retransmission block reaches the reception-side storage unit 162 before the timing to be read from the reception-side storage unit 162.

  In this embodiment, the retransmission request unit 167 of the reception processing device 107 can narrow the retransmission request interval when the retransmission request remaining time is less than the predetermined time than when the retransmission request remaining time is equal to or longer than the predetermined time. In the conventional ARQ, the receiving side makes a retransmission request when detecting a transmission error or signal loss. In this method, since the receiving side makes a retransmission request after confirming the arrival of a signal, the frequency of retransmission requests decreases in a transmission line with a large propagation delay even though there is a free band in the transmission line. was there. On the other hand, in the present embodiment, when the retransmission request remaining time of an unstored block in which a transmission error has occurred is short, the retransmission request unit 167 can increase the frequency of performing a retransmission request for the block. The possibility of reaching the reception-side storage unit 162 before the timing to be read from the storage unit 162 increases.

  According to the present invention, there is a usefulness that a transmission error can be detected even in a TS transmission line in which rate conversion is performed in the middle of the transmission line, and a null packet is inserted or a PCR is rewritten.

DESCRIPTION OF SYMBOLS 100 Retransmission system 101 Transmission processing apparatus 103 Transmitter 105 Receiver 107 Reception processing apparatus 121 PCR lock part 123 1st PID change part (1st change part)
124 2nd PID change part (2nd change part)
125 Control data calculation unit (calculation unit)
127 First MUX unit 128 Acquisition unit 129 Transmission side reading unit 130 Transmission side storage unit 131 Retransmission PID change unit (third change unit)
133 PCR packet part (generation part)
137 Second MUX part (synthesis part)
151 PCR lock unit 153 filter unit 155 initial transmission block determination unit 157 retransmission PID restoration unit 159 retransmission block determination unit 161 PID restoration unit 162 reception side storage unit 163 reception side reading unit 167 retransmission request unit 169 transmission unit

Claims (7)

In a transmission processing device that processes a TS signal to be transmitted to a reception processing device and includes a null packet and a first PCR packet,
A first changing unit that converts the null packet into a dummy packet having a packet identifier different from the null packet;
A second changing unit that makes the packet identifier of the time information acquisition destination in the TS signal different from the packet identifier of the first PCR packet;
A generating unit that generates time information synchronized with the first PCR packet and generates a second PCR packet having the packet identifier of the time information acquisition destination;
A transmission processing apparatus comprising: a synthesis unit that synthesizes the TS signal subjected to the processing of the first and second changing units and the second PCR packet. The transmission processing apparatus according to claim 1,
A calculation unit for calculating an error detection code for detecting a transmission error of the TS signal subjected to the processing of the first and second changing units;
An acquisition unit that acquires a retransmission request for a signal that was not correctly acquired in the reception processing device;
The acquisition unit further includes a third changing unit that makes a packet identifier of the TS signal by retransmission out of the TS signal subjected to the processing of the first and second changing units different from the TS signal by initial transmission. Gets a resend request,
The transmission processing apparatus, wherein the combining unit combines the TS signal by the retransmission, the TS signal by the initial transmission, and the second PCR packet. In a retransmission system including a transmission processing device that processes a TS signal to be transmitted to a reception processing device and includes a null packet and a first PCR packet, and the reception processing device that acquires the TS signal,
The transmission processing device includes:
a. converting the null packet into a dummy packet having a packet identifier different from the null packet;
b. making the packet identifier of the time information acquisition destination in the TS signal different from the packet identifier of the first PCR packet;
c. generating a second PCR packet having time information synchronized with the first PCR packet and having the packet identifier of the time information acquisition destination;
d. combining the TS signal subjected to the processing a. and b. and the second PCR packet;
The reception processing device includes:
A retransmission system for transmitting a retransmission request for a signal that has not been acquired correctly to the transmission processing apparatus. The retransmission system according to claim 3,
The reception processing device includes:
Storing the acquired TS signal;
Send the stored TS signal at a predetermined timing,
Obtain the remaining time for which a retransmission request is possible from the predetermined timing,
A retransmission system that determines a retransmission request interval of the retransmission request based on the remaining time. 5. The retransmission system according to claim 4, wherein the reception processing device is
When the remaining time becomes less than the predetermined time, the retransmission request interval is narrower than when the remaining time is equal to or longer than the predetermined time. In a transmission processing method in which a transmission processing device processes a TS signal to be transmitted to a reception processing device and includes a null packet and a first PCR packet.
converting the null packet into a dummy packet having a packet identifier different from the null packet;
b. differentiating the packet identifier of the time information acquisition destination in the TS signal from the packet identifier of the first PCR packet;
c. generating a second PCR packet having time information synchronized with the first PCR packet and having the packet identifier of the time information acquisition destination;
d. A transmission processing method including the step of combining the TS signal subjected to steps a. and b. and the second PCR packet. A TS signal to be transmitted to the reception processing device, and a computer constituting the transmission processing device that processes the TS signal including the null packet and the first PCR packet,
converting the null packet into a dummy packet having a packet identifier different from the null packet;
b. differentiating the packet identifier of the time information acquisition destination in the TS signal from the packet identifier of the first PCR packet;
c. generating a second PCR packet having time information synchronized with the first PCR packet and having the packet identifier of the time information acquisition destination;
d. A program for executing the step of synthesizing the TS signal subjected to steps a. and b. and the second PCR packet.

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