Measuring device and receiving device

Abstract

To provide a measuring apparatus and a receiving apparatus, with which a bit error rate can be properly measured even when actual video signals, etc. are assumed.SOLUTION: A measuring apparatus includes: a receiving part receiving a received signal including an error correction block in which packets of one layer or more are multiplexed; and a measuring part measuring the bit error rate of the received signal based on at least one of known bits included in the header of the error correction block and known bits included in the header of the packets of one layer or more. When an n-1th (n is an integer of 2 or more) error correction block and an n-th error correction block are continuously incorrect, the measuring part excludes the n-th error correction block from the measuring object of the bit error rate, and when the n-1th error correction block and the n-th error correction block are not continuously incorrect, the measuring part includes the n-th error correction block in the measuring object of the bit error rate.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a measuring device and a receiving device. [Background technology]

[0002] In terrestrial digital broadcasting (e.g., ISDB-T; Integrated Services Digital Broadcasting-Terrestrial), Viterbi codes are used as error-correcting codes. The bits obtained by Viterbi decoding are re-encoded, and the bit error rate is measured by comparing the re-encoded bit string with the hard-decision bit string before Viterbi decoding.

[0003] On the other hand, in the advanced terrestrial broadcasting system, a method of measuring the bit error rate has been proposed that uses packets containing a known pseudo-random signal (for example, Patent Document 1). However, when considering actual video signals, etc., it is not possible to include a known pseudo-random signal in a packet, so the bit error rate is calculated from the packet error rate. The packet error rate is detected based on the continuity of packets obtained by error correction decoding, and the bit rate is calculated assuming that half of the erroneous packets are erroneous. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-216327 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in the advanced terrestrial broadcasting system, a low density parity check (LDPC) code is used as an error correcting code.

[0006] Under such circumstances, the inventors have conducted extensive research and found that when an LDPC code is used, the bit error rate changes significantly near a threshold value that determines whether or not the reception quality (for example, CNR (Carrier to Noise Ratio) or reception signal strength) satisfies a desired quality.

[0007] Therefore, the present invention has been made to solve the above-mentioned problems, and aims to provide a measuring device and a receiving device that can appropriately measure the bit error rate even when an actual video signal, etc. is assumed. [Means for solving the problem]

[0008] The measurement device according to the first disclosure comprises a receiving unit that receives a received signal including an error correction block into which packets of one or more layers are multiplexed, and a measurement unit that measures the bit error rate of the received signal based on at least one of a known bit included in the header of the error correction block and a known bit included in the header of a packet of one or more layers, wherein the measurement unit excludes the n-1th (n is an integer greater than or equal to 2)th error correction block from the target for measuring the bit error rate when the n-1th error correction block and the nth error correction block contain consecutive errors, and includes the nth error correction block from the target for measuring the bit error rate when the n-1th error correction block and the nth error correction block do not contain consecutive errors.

[0009] A receiving device according to the second disclosure includes the measuring device according to the first disclosure. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a measuring device and a receiving device that are capable of appropriately measuring the bit error rate even when an actual video signal or the like is assumed. [Brief explanation of the drawings]

[0011] [Figure 1]FIG. 1 is a diagram showing a digital wireless transmission system 10 according to an embodiment. [Figure 2] FIG. 2 is a diagram showing a measurement device 200 according to an embodiment. [Figure 3] FIG. 3 is a diagram illustrating an FEC block according to the embodiment. [Figure 4] FIG. 4 is a diagram illustrating a TLV packet according to the embodiment. [Figure 5] FIG. 5 is a diagram for explaining an application scene according to the embodiment. [Figure 6] FIG. 6 is a diagram showing a measurement method according to an embodiment. [Figure 7] FIG. 7 is a diagram for explaining Experiment 1. [Figure 8] FIG. 8 is a diagram for explaining Experiment 2. [Figure 9] FIG. 9 is a diagram illustrating an FEC block according to the first modification. [Figure 10] FIG. 10 is a diagram showing a measurement device 200 according to the first modified example. [Figure 11] FIG. 11 is a diagram illustrating an IP packet according to the first modification. [Figure 12] FIG. 12 is a diagram illustrating an IP packet according to the first modification. [Figure 13] FIG. 13 is a diagram showing an MMTP packet according to the first modification. DETAILED DESCRIPTION OF THE INVENTION

[0012] Next, an embodiment of the present invention will be described. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and the dimensional ratios may differ from those of the actual parts.

[0013] Therefore, specific dimensions should be determined with reference to the following explanation. Of course, the dimensional relationships and ratios may differ between the drawings.

[0014] [Disclosure Summary] The measurement device according to the outline of the disclosure comprises a receiving unit that receives a received signal including an error correction block in which packets of one or more layers are multiplexed, and a measurement unit that measures the bit error rate of the received signal based on at least one of a known bit included in the header of the error correction block and a known bit included in the header of a packet of one or more layers, wherein the measurement unit excludes the n-1th (n is an integer greater than or equal to 2)th error correction block from the target for measuring the bit error rate when the n-1th error correction block and the nth error correction block contain consecutive errors, and includes the nth error correction block from the target for measuring the bit error rate when the n-1th error correction block and the nth error correction block do not contain consecutive errors.

[0015] In the outline of the disclosure, the measurement device measures the bit error rate of a received signal based on at least one of a known bit included in the header of an error correction block and a known bit included in the header of a packet at one or more layers, and excludes the nth error correction block from the bit error rate measurement target if the (n-1)th error correction block and the nth error correction block contain consecutive errors, and includes the nth error correction block from the bit error rate measurement target if the (n-1)th error correction block and the nth error correction block do not contain consecutive errors. With this configuration, when considering actual video signals, etc., the bit error rate can be measured more appropriately than when the bit error rate is calculated from the packet error rate.

[0016] [Embodiment] (Digital Wireless Transmission System) A digital wireless transmission system according to an embodiment will be described below. Fig. 1 is a diagram showing a digital wireless transmission system 10 according to an embodiment. As shown in Fig. 1, the digital wireless transmission system includes a transmitting device 100 and a measuring device 200.

[0017] In an embodiment, the digital wireless transmission system 10 may be a wireless transmission system related to an advanced terrestrial broadcasting standard. In the digital wireless transmission system 10, one or more packets formed by a broadcast signal are multiplexed into an error correction block, and one or more error correction blocks are multiplexed into a wireless transmission frame.

[0018] The packets may be referred to as TLV (Type Length Value) packets. The TLV packets may be interchangeable with IP packets. The TLV packets may be of variable length. In the embodiment, the TLV packets are packets that contain actual video signals, rather than packets that contain known pseudo-random signals used to measure bit error rates.

[0019] The error correction block may be referred to as a forward error correction (FEC) block. A low-density parity-check (LDPC) code may be used as the error correction code. The FEC block may have a fixed length.

[0020] The radio transmission frame may be an OFDM frame to which Orthogonal Frequency Division Multiplexing (OFDM) is applied.

[0021] The transmitting device 100 may be a studio of a broadcasting station or a transmitting station, and transmits an OFDM frame (transmission signal).

[0022] The measuring apparatus 200 receives an OFDM frame (received signal) from the transmitting apparatus 100. As described above, the OFDM frame includes one or more FEC blocks. Each of the one or more FEC blocks includes one or more TLV packets. The measuring apparatus 200 measures the bit error rate of the OFDM frame (received signal).

[0023] (Measuring equipment) The measuring device according to the embodiment will be described below. Fig. 2 is a diagram showing a measuring device 200 according to the embodiment.

[0024] As shown in FIG. 2, the measurement device 200 includes a demodulation unit 201, an error correction decoding unit 203, a determination unit 205, a first extraction unit 207, a second extraction unit 209, an analysis unit 211, a comparison unit 213, and a counting unit 215.

[0025] The demodulation unit 201 demodulates the OFDM frame. The modulation level used in the demodulation method may be 64QAM (Quadrate Amplitude Modulation). The modulation level may be 256QAM or 1024QAM. The modulation level may be a modulation level greater than 1024QAM (for example, 4096QAM).

[0026] The error correction decoding unit 203 applies error correction decoding to the FEC blocks included in the demodulated OFDM frame. The error correction code used in the error correction decoding may be LDPC.

[0027] The determination unit 205 determines whether or not there is an error in the FEC block by a parity check.

[0028] The first extraction unit 207 extracts the header of the FEC block. As will be described later, the header of the FEC block includes a bit string indicating the start position of the first TLV packet included in the FEC block, and the bit string indicating the start position of the first TLV packet includes a fixed value.

[0029] The second extraction unit 209 separates the TLV packets from the FEC block and extracts the headers of the TLV packets. As will be described later, the headers of the TLV packets contain fixed values. The headers of the TLV packets may contain a bit string that indicates the type of the TLV packet.

[0030] The analyzing unit 211 analyzes the header of the TLV packet included in the FEC block that the determining unit 205 has determined to be error-free.

[0031] First, when the n-1th (n is an integer equal to or greater than 2)th FEC block is not erroneous and the nth FEC block is erroneous, the analyzer 211 may estimate the known bits included in the header of the nth FEC block based on the header of the TLV packet included in the n-1th FEC block. The known bits included in the header of the nth FEC block may be a bit string indicating the start position of the first TLV packet included in the nth FEC block. The known bits included in the nth FEC block do not have to include the fixed value included in the header of the nth FEC block.

[0032] Specifically, the header of the TLV packet included at the end of the n-1th FEC block includes a bit string indicating the length of the TLV packet. Therefore, the analysis unit 211 can estimate the starting position of the first TLV packet included in the nth FEC block based on the length of the TLV packet included at the end of the n-1th FEC block. In other words, the analysis unit 211 can estimate the known bits (bit string indicating the starting position of the first TLV packet) included in the header of the nth FEC block based on the length of the TLV packet included at the end of the n-1th FEC block.

[0033] Second, when the (n-1)th FEC block is not erroneous and the nth FEC block is erroneous, the analyzer 211 may estimate the known bits included in the header of the TLV packet included in the nth FEC block based on the known bits included in the header of the TLV packet included in the (n-1)th FEC block. The known bits included in the header of the TLV packet included in the nth FEC block may include a bit string indicating the type of the TLV packet.

[0034] Specifically, it is assumed that the type of the TLV packet included in the (n-1)th FEC block is the same as the type of the TLV packet included in the nth FEC block. Therefore, the analysis unit 211 can estimate the type of the TLV packet included in the nth FEC block based on the type of the TLV packet included in the (n-1)th FEC block. In other words, the analysis unit 211 can estimate the known bits (bit string indicating the type of TLV packet) included in the header of the nth FEC block based on the header of the TLV packet included in the (n-1)th FEC block.

[0035] When the (n-1)th FEC block is not erroneous and the nth FEC block is erroneous, the comparison unit 213 compares whether the bits contained in the nth FEC block received from the transmitting device 100 match known bits.

[0036] The known bits may include a fixed value included in the header of the nth FEC block, or may include a fixed value included in the header of a TLV packet included in the nth FEC block.

[0037] The known bits may include known bits estimated by the analysis unit 211. The known bits estimated by the analysis unit 211 may include known bits included in the header of the n-th FEC block (a bit string indicating the start position of the first TLV packet), or may include known bits included in the header of a TLV packet included in the n-th FEC block (a bit string indicating the type of TLV packet).

[0038] The counting unit 215 counts the number of correct bits and the number of error bits, and measures the bit error rate of the received signal based on the number of correct bits and the number of error bits.

[0039] Here, if the (n-1)th FEC block and the nth FEC block contain consecutive errors, the counting unit 215 does not count the number of correct bits and the number of error bits for the nth FEC block. In other words, if the (n-1)th FEC block and the nth FEC block contain consecutive errors, the nth FEC block is excluded from the measurement of the bit error rate.

[0040] On the other hand, when there are no consecutive errors in the (n-1)th FEC block and the nth FEC block, the counting unit 215 counts the number of correct bits and the number of error bits for the nth FEC block. In other words, when there are no consecutive errors in the (n-1)th FEC block and the nth FEC block, the nth FEC block is included in the measurement target for the bit error rate.

[0041] The following cases are possible as cases where the (n-1)th FEC block and the nth FEC block are consecutive and error-free.

[0042] (A) Case where neither the n-1th FEC block nor the nth FEC block is error-free (B) Case where the n-1th FEC block is not error-free and the nth FEC block is error-free (C) Case where the n-1th FEC block is erroneous and the nth FEC block is not erroneous.

[0043] In case (B), the above-described analyzer 211 may estimate a known bit included in the header of the n-th FEC block, or may estimate a known bit included in the header of a TLV packet included in the n-th FEC block. In cases (A) and (C), such estimation is not necessary because neither of the n-th FEC blocks is erroneous.

[0044] In the embodiment, the demodulation unit 201 may be an example of a receiving unit that receives an OFDM frame (received signal) including an FEC block in which one or more TLV packets are multiplexed. The determination unit 205, the first extraction unit 207, the second extraction unit 209, the analysis unit 211, the comparison unit 213, and the counting unit 215 may be an example of a measurement unit that measures the bit error rate of the received signal based on known bits included in the FEC block.

[0045] (FEC block) An FEC block according to an embodiment will be described below. Fig. 3 is a diagram showing an FEC block according to an embodiment. As shown in Fig. 3, the FEC block includes a header, a main signal, a BCH code parity, and an LDPC code parity.

[0046] The header includes a bit string indicating the start position of the first TLV packet included in the FEC block. The bit string indicating the start position of the first TLV packet may be expressed as the number of bytes from the start of the FEC block excluding the FEC block header. If the start position of the first TLV packet does not exist, the bit string indicating the start position of the first TLV packet may be expressed as "0xFFFF".

[0047] For example, if the header is 16 bits and the TLV packet has a variable length of 0 to 7533 bytes, the bit string indicating the start position of the first TLV packet can be expressed with 13 bits, so the first 3 bits can be treated as a fixed value ("000"). Therefore, the header of the FEC block may contain a fixed value ("000").

[0048] In such a case, known bits included in the header of the FEC block (for example, a fixed value and 16 bits indicating the start position of the TLV packet) can be used as target bits for measuring the bit error rate.

[0049] (TLV packet) The TLV packet according to the embodiment will be described below. Fig. 4 is a diagram showing a TLV packet according to the embodiment. As shown in Fig. 4, the TLV packet includes a header and data.

[0050] The header may include a fixed value, a bit string indicating the type of the TLV packet (packet type), and a bit string indicating the length of the TLV packet (data length). The fixed value is 8 bits, and the fixed value ("01") represents a delimiter for identifying the boundary of the TLV packet, and the fixed value ("111111") may be used as a reserved bit.

[0051] Although not particularly limited, the packet type may be 8 bits. Packet types may include IPv4 packets ("0x01"), IPv6 packets ("0x02"), packets with compressed headers ("0x03"), packets containing transmission control signals ("0xFE"), null packets ("0xFF"), and other types. The data length may be 16 bits.

[0052] In such a case, known bits (for example, 16 bits of a fixed value and packet type) included in the header of the TLV packet can be used as target bits for measuring the bit error rate.

[0053] (Applicable scenes) An application scenario according to the embodiment will be described below. Fig. 5 illustrates an application scenario according to the embodiment. Here, a case where FEC block #1 is not erroneous and FEC block #2 is erroneous (the above-mentioned case (B)) will be described.

[0054] 5, the header of an FEC block is represented by "BH" and the header of a TLV packet is represented by "PH." This illustrates a case where FEC block #1 includes TLV packet #1 and part of TLV packet #2, and FEC block #2 includes the remaining part of TLV packet #2, TLV packet #3, and part of TLV packet #4.

[0055] First, for FEC block #1, since there is no error in FEC block #1, the start position of TLV packet #1 can be identified based on BH #1 of FEC block #1. Furthermore, the type of TLV packet #1 can be identified based on PH #1, and the type of TLV packet #2 can be identified based on PH #2.

[0056] Second, because FEC block #2 contains an error, the start position of TLV packet #3 cannot be identified based on BH#2 of FEC block #2. Also, the type of TLV packet #3, etc. cannot be identified based on PH#3, etc.

[0057] In an embodiment, in such a case, the measurement device 200 performs the following operations.

[0058] First, the measuring device 200 determines the length of TLV packet #2 based on PH#2, thereby estimating the start position of TLV packet #3 included in FEC block #2. With this configuration, it is possible to identify the known bit string included in BH#2 of FEC block #2.

[0059] Second, the measuring device 200 assumes that the type of TLV packet #2 is the same as the type of TLV packet #3, and estimates the type of TLV packet #3 based on the type of TLV packet #2. With this configuration, it is possible to identify the known bit string included in PH #3 of TLV packet #3.

[0060] Note that the measuring device 200 may assume that the type of TLV packet #1 is the same as the type of TLV packet #3 and may infer the type of TLV packet #3 based on the type of TLV packet #1. If the measuring device 200 can identify TLV packet #4 because the TLV packet has a fixed length or for other reasons, it may infer the type of TLV packet #4 based on the type of TLV packet #2 (or TLV packet #1).

[0061] (Measurement method) The measurement method according to the embodiment will be described below. Fig. 6 is a diagram showing the measurement method according to the embodiment. In Fig. 6, FEC block #n means the nth FEC block, and FEC block #n-1 means the n-1th FEC block.

[0062] 6, in step S10, the measurement device 200 determines whether or not there is an error in the FEC block #n. If there is no error in the FEC block #n, the measurement device 200 executes the process of step S13, and if there is an error in the FEC block #n, the measurement device 200 executes the process of step S14.

[0063] In step S11, the measurement device 200 determines whether or not there is an error in the FEC block #n-1. If there is no error in the FEC block #n-1, the measurement device 200 executes the process of step S12, and if there is an error in the FEC block #n-1, the measurement device 200 executes the process of step S16.

[0064] In step S12, the measurement apparatus 200 compares whether or not the bits included in the n-th FEC block received from the transmission apparatus 100 match the known bits. If the comparison result shows a match, the measurement apparatus 200 executes the process of step S13, and if the comparison result shows a match, the measurement apparatus 200 executes the process of step S14.

[0065] In step S13, the measurement device 200 counts the number of correct bits. The number of correct bits includes the number of known bits contained in the correct FEC block #n. Furthermore, the number of correct bits includes the number of bits determined to match in the comparison result in step S12.

[0066] In step S14, measurement apparatus 200 counts the number of error bits, including the number of bits determined in step S12 as not matching.

[0067] In step S15, the measurement device 200 determines whether the number of observed bits (i.e., the sum of the number of correct bits and the number of error bits) is equal to or greater than a threshold. If the number of observed bits is equal to or greater than the threshold, the measurement device 200 executes the process of step S17. If the number of observed bits is less than the threshold, the measurement device 200 executes the process of step S16. The threshold defines a number of observed bits sufficient to measure the bit error rate.

[0068] In step S16, the measurement apparatus 200 substitutes n+1 for n and proceeds to the checking operation for the next FEC block.

[0069] In step S17, the measurement apparatus 200 measures the bit error rate of the received signal based on the number of correct bits and the number of error bits.

[0070] 6, the process of step S11 is a process of determining whether or not there are consecutive errors in FEC block #n-1 and FEC block #n. If there are consecutive errors in FEC block #n-1 and FEC block #n, the processes of steps S12 to S14 are not executed, and FEC block #n is excluded from the measurement target of the bit error rate.

[0071] (Action and effect) In the embodiment, the measuring device 200 is premised on measuring the bit error rate of the received signal based on at least one of a known bit included in the header of the FEC block and a known bit included in the header of the TLV packet, and excludes the nth FEC block from the bit error rate measurement target if the (n-1)th FEC block and the nth FEC block contain consecutive errors, and includes the nth FEC block from the bit error rate measurement target if the (n-1)th FEC block and the nth FEC block do not contain consecutive errors. With this configuration, when an actual video signal or the like is assumed, the bit error rate can be measured more appropriately than when the bit error rate is calculated from the packet error rate.

[0072] [Experimental Results] The experimental results are explained below.

[0073] In Experiment 1, when the number of bits in an FEC block is "m", if there is an error in even one bit in the FEC block, the FEC block is considered to be in error, and the block error rate (FBER) of the FEC block was calculated according to the following equation (1) using the bit error rate (BER).

[0074] FBER=1-(1-BER) m ...Formula (1)

[0075] Under these conditions, when the LDPC coding rate is 9 / 16, the probability of consecutive errors in the FEC block (hereinafter referred to as the consecutive error probability) is calculated using the above formula (1), and the relationship between the bit error rate (BER) and the consecutive error probability of the FEC block is confirmed. The confirmation results are shown in Figure 7.

[0076] As shown in Figure 7, when the BER is 10 -5 , the probability of successive errors in the FEC block is 10 -1 Furthermore, it is expected that it will be used as a criterion for determining whether or not a signal can be received. -7 At a BER of , the probability of successive errors in an FEC block is 10 -5 is.

[0077] Therefore, it is expected that it will be used as a criterion for determining whether or not a signal can be received. -7 In the vicinity of this BER, the probability of consecutive errors in the FEC blocks is considered to be sufficiently small, and if there are consecutive errors in FEC block #n-1 and FEC block #n, excluding FEC block #n from the bit error rate measurement targets is considered to have little effect on the bit error rate calculation.

[0078] In experiment 2, the LDPC coding rate was 9 / 16 and the number of observed bits was 10 7The relationship between CNR (Carrier to Noise Ratio) and BER was confirmed for the case of 1000 bits.

[0079] Comparative Example 1 is an example in which a TLV packet containing a known pseudo-random signal is used instead of an actual video signal, etc. Comparative Example 1 is an example in which the BER is measured based on the result of comparing the bits contained in the received signal with the known pseudo-random signal. In Comparative Example 1, since a known pseudo-random signal is used, it is assumed that the reliability of the BER is the highest.

[0080] Comparative Example 2 is an example that uses an actual video signal, etc. In Comparative Example 2, erroneous TLV packets were detected based on the continuity of TLV packets obtained by error correction decoding, and the BER was measured under the assumption that half of the erroneous TLV packets were erroneous.

[0081] The examples are examples using actual video signals, etc. In the examples, as described in the embodiment, the BER was measured based on known bits included in the header of the FEC block and the header of the TLV packet. In the examples, if the (n-1)th FEC block and the nth FEC block were consecutively erroneous, the nth FEC block was excluded from the bit error rate measurement target.

[0082] The results of checking the relationship between CNR and BER for Comparative Example 1, Comparative Example 2, and the example are shown in FIG.

[0083] 8, when focusing on Comparative Example 2 and the Example, which use actual video signals, etc., it was confirmed that a relatively high BER was measured in Comparative Example 2 compared to Comparative Example 1, which is assumed to be the most reliable. On the other hand, it was confirmed that a BER similar to that of Comparative Example 1, which is assumed to be the most reliable, was measured in the Example, when compared to Comparative Example 2.

[0084] That is, when an actual video signal or the like is used, it was confirmed that the BER measurement accuracy of the embodiment is significantly improved compared to Comparative Example 2, which is a conventional method.

[0085] [Change Example 1] Modification 1 of the embodiment will be described below, focusing mainly on the differences from the embodiment.

[0086] Specifically, in the embodiment, TLV packets are exemplified as packets multiplexed into an FEC block, whereas in Modification 1, a case where packets of one or more layers are multiplexed into an FEC block is exemplified.

[0087] For example, as shown in FIG. 9, one or more TLV packets may be multiplexed into an FEC block, IP packets may be multiplexed into the TLV packets, and MMTP (MPEG Media Transport Protocol) packets may be multiplexed into the IP packets.

[0088] In the first modification, the known bits included in the headers of IP packets and MMTP packets may be used to measure the bit error rate of the received signal, similar to the known bits included in the headers of TLV packets.

[0089] (Measuring equipment) A measurement device according to Modification 1 will be described below. Fig. 10 is a diagram showing a measurement device 200 according to the embodiment. In Fig. 10, the same components as those in Fig. 2 are denoted by the same reference numerals. Therefore, a description of the same components as those in Fig. 2 will be omitted.

[0090] As shown in FIG. 10, the measurement device 200 has a third extraction unit 251, an analysis unit 253, a fourth extraction unit 261, and an analysis unit 263 in addition to the configuration shown in FIG.

[0091] The third extraction unit 251 separates the IP packet from the TLV packet and extracts the header of the IP packet. The header of the IP packet includes known bits, which will be described later.

[0092] The analyzing unit 253 analyzes the header of the IP packet included in the FEC block that the determining unit 205 has determined to be error-free.

[0093] When the n-1th FEC block is not erroneous and the nth FEC block is erroneous, the analysis unit 253 may estimate the known bits contained in the header of the IP packet contained in the nth FEC block based on the known bits contained in the header of the IP packet contained in the n-1th FEC block.

[0094] The fourth extraction unit 261 separates the MMTP packet from the IP packet and extracts the header of the MMTP packet. The header of the MMTP packet includes known bits, which will be described later.

[0095] The analysis unit 263 analyzes the header of the MMTP packet included in the FEC block that the determination unit 205 has determined to be error-free.

[0096] When the n-1th FEC block is not erroneous and the nth FEC block is erroneous, the analysis unit 263 may estimate the known bits contained in the header of the MMTP packet contained in the nth FEC block based on the known bits contained in the header of the MMTP packet contained in the n-1th FEC block.

[0097] (IP packet) The following describes an IP packet according to Modification 1. Figures 11 and 12 are diagrams showing an IP packet according to Modification 1. The IP packet includes a header and a payload.

[0098] As shown in Figure 11, the header of an IPv4 IP packet includes a context identifier, a sequence number, a context identification header type, a partial IPv4 header, and a partial UDP header. The partial IPv4 header and the partial UDP header may be replaced by the partial IPv4 header identifier. On the other hand, the header of an IPv6 IP packet includes a context identifier, a sequence number, a context identification header type, a partial IPv6 header, and a partial UDP header. The partial IPv6 header and the partial UDP header may be omitted.

[0099] As shown in Figure 12, the partial IPv4 header includes a version, header length, service identification, identifier, flags, fragment offset, time to live, protocol, source address, and destination address. On the other hand, the partial IPv6 header includes a version, traffic class, flow label, next header, hop limit, source address, and destination address. The partial IPv4 header and the partial IPv6 header may be collectively referred to as partial headers.

[0100] Here, the following bits can be used as known bits included in the header of the IP packet included in the n-th FEC block.

[0101] In Option 1A, the known bits may include a context identifier. The context identifier is an identifier that indicates the flow of header-compressed IP packets. The IP packet flow is a flow that has a common source address and destination address. Here, since it is not expected that the flow of IP packets will change, the context identifier can be treated as a fixed value. In other words, after receiving an FEC block that is determined to be error-free by the determining unit 205, the correct context identifier can be identified, and the identified context identifier can be treated as a fixed value.

[0102] In option 1B, the known bits may include a sequence number. Specifically, when the (n-1)th FEC block is not erroneous, the above-described analyzer 253 can estimate the sequence number of the IP packet included in the (n-1)th FEC block from the sequence number of the IP packet included in the (n-1)th FEC block, even if the (n-1)th FEC block is erroneous. Therefore, when the (n-1)th FEC block is not erroneous and the (n-1)th FEC block is erroneous, the sequence number can be treated as a fixed value.

[0103] In Option 1C, the known bits may include a context identification header type. The context identification header type identifies whether or not a partial header is included in the header of an IP packet. For example, assuming a case in which partial headers are included in the header of an IP packet at a predetermined period, the above-mentioned analysis unit 253 can estimate the context identification header type based on the sequence number and the predetermined period. Therefore, in a case in which partial headers are included in the header of an IP packet at a predetermined period, the context identification header type can be treated as a fixed value.

[0104] In Option 1D, known bits may be at least a part of the bits that make up the partial header. Here, it is not assumed that the flow of the IP packet will change. Therefore, in a partial IPv4 header, bits other than the identifier, namely, version, header length, service identifier, flags, fragment offset, time to live, protocol, source address, and destination address, can be treated as fixed values. In a partial IPv6 header, all bits, namely, version, traffic class, flow label, next header, hop limit, source address, and destination address, can be treated as fixed values. It goes without saying that Option 1D is an option that applies to IP packets that include partial headers.

[0105] Two or more options selected from the above-mentioned options 1A to 1D may be combined.

[0106] (MMTP packet) The following describes an MMTP packet according to Modification 1. Fig. 13 is a diagram showing an MMTP packet according to Modification 1. The MMTP packet includes a header and a payload.

[0107] As shown in Figure 13, the header of an MMTP packet includes a version, a packet counter flag, an FEC type, an unused extension header flag, a RAP (Random Access Point) flag, an unused payload type, a packet identifier, a delivery timestamp, a packet sequence number, a packet counter, an extension header type, an extension header length, and an extension header area.

[0108] Here, the following bits can be used as known bits included in the header of the MMTP packet included in the n-th FEC block.

[0109] In option 2A, the known bits may include a packet sequence number. The packet sequence number is the order of MMTP packets with the same packet identifier. It is assumed that the packet identifier does not change for the same content. Therefore, if the n-1th FEC block is not erroneous, the above-mentioned analysis unit 263 can estimate the packet sequence number of the MMTP packet included in the n-th FEC block from the packet sequence number of the MMTP packet included in the n-1th FEC block, even if the n-th FEC block is erroneous. Therefore, if the n-1th FEC block is not erroneous and the n-th FEC block is erroneous, the packet sequence number can be treated as a fixed value.

[0110] In option 2B, the known bits may include a packet counter. The packet counter is the order of MMTP packets in the same IP packet flow. The IP packet flow is not expected to change. Therefore, if the (n-1)th FEC block is not erroneous, the above-mentioned analysis unit 263 can estimate the packet counter of the MMTP packet included in the (n-1)th FEC block from the packet counter of the MMTP packet included in the (n-1)th FEC block, even if the (n-1)th FEC block is erroneous. Therefore, if the (n-1)th FEC block is not erroneous and the (n-1)th FEC block is erroneous, the packet counter can be treated as a fixed value.

[0111] In Option 2C, the known bits may include bits excluding the delivery timestamp, packet sequence number, packet counter, extension header type, extension header length, and extension header field, i.e., version, packet counter flag, FEC type, unused, extension header flag, RAP flag, unused, payload type, and packet identifier. Because these bits are not expected to change, they can be treated as fixed values. In other words, after receiving an FEC block determined to be error-free by the determining unit 205, the correct bits can be identified as the above-mentioned bits, and the identified correct bits can be treated as fixed values.

[0112] Two or more options selected from the above-mentioned options 2A to 2C may be combined.

[0113] (Action and effect) In Modification 1, the measurement device 200 measures the bit error rate of the received signal based on known bits included in the headers of IP packets and MMTP packets. With this configuration, similar to the embodiment, when an actual video signal or the like is assumed, the bit error rate can be measured more appropriately than when the bit error rate is calculated from the packet error rate.

[0114] [Other embodiments] Although the present invention has been described by the above disclosure, the descriptions and drawings that form part of this disclosure should not be understood as limiting the present invention. From this disclosure, various alternative embodiments, examples, and operating techniques will become apparent to those skilled in the art.

[0115] Although not particularly limited, the above disclosure may be expressed as follows. Assuming an FEC block in which packets of one or more layers are multiplexed, the measuring device 200 measures the bit error rate of a received signal based on at least one of a known bit included in the header of the FEC block and a known bit included in the header of packets of one or more layers. Here, the packets of one or more layers include at least one of TLV packets, IP packets, and MMTP packets. TLV packets may be referred to as upper packets that constitute the highest layer. At least one of IP packets and MMTP packets may be referred to as lower packets of one or more layers that are multiplexed into the TLV packets.

[0116] Although not particularly limited, the target bits used in measuring the bit error rate may be considered to be known bits (or bits corresponding to known bits) included in one or more headers selected from the header of an FEC block, the header of a TLV packet, the header of an IP packet, and the header of an MMTP packet. The known bits may be fixed values ​​or estimated values. The estimated values ​​may be values ​​estimated based on the (n-1)th FEC block when the (n-1)th FEC block is not erroneous.

[0117] In the above disclosure, if the (n-1)th FEC block and the nth FEC block are erroneous consecutively, the nth FEC block is excluded from the measurement of the bit error rate. However, the above disclosure is not limited to this. Even if the (n-1)th FEC block and the nth FEC block are erroneous consecutively, the fixed value included in the header of the nth FEC block may be included in the measurement of the bit error rate.

[0118] In the above disclosure, the case where the TLV packet has a variable length has been mainly described. However, the above disclosure is not limited to this. The TLV packet may have a fixed length. In such a case, the bit string indicating the length of the TLV packet (the data length shown in FIG. 4) may be treated as a known bit. In other words, the bit string indicating the length of the TLV packet may be included in the measurement target of the bit error rate.

[0119] In the above disclosure, the case where the TLV packet is of variable length has been mainly described. However, the above disclosure is not limited to this. The TLV packet may be of fixed length. In such a case, even if the (n-1)th FEC block and the nth FEC block are consecutively erroneous, it is possible to identify the start position of the first TLV packet included in the nth FEC block. Therefore, the known bits included in the header of the nth FEC block (the entire bit string indicating the start position of the first TLV packet) may be included in the bit error rate measurement.

[0120] The above disclosure has mainly described the measurement device 200. However, the above disclosure is not limited to this. The measurement device 200 may be provided in a receiving device configured to output a video image based on a reception signal received from the transmitting device 100.

[0121] In the above disclosure, the TLV packet is a packet containing an actual video signal, etc. However, the above disclosure is not limited to this. The TLV packet may be a packet containing an actual audio signal, or may be a packet containing an actual signal related to other multimedia.

[0122] Although not specifically mentioned in the above disclosure, a program may be provided that causes a computer to execute each process performed by the measurement device 200. The program may also be recorded on a computer-readable medium. Using the computer-readable medium, the program can be installed on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM.

[0123] Alternatively, a chip may be provided that is configured by a memory that stores a program for executing each process performed by the measurement device 200 and a processor that executes the program stored in the memory. [Explanation of symbols]

[0124] 10...digital wireless transmission system, 100...transmitting device, 200...measuring device, 201...demodulating section, 203...error correction decoding section, 205...determining section, 207...first extracting section, 209...second extracting section, 211...analyzing section, 213...comparing section, 215...counting section, 251...third extracting section, 253...analyzing section, 261...fourth extracting section, 263...analyzing section

Claims

1. a receiving unit that receives a received signal including an error correction block in which packets of one or more layers are multiplexed; a measurement unit that measures a bit error rate of the received signal based on at least one of a known bit included in a header of the error correction block and a known bit included in a header of a packet of one or more layers, The measurement unit If the n-1th (n is an integer of 2 or more) error correction block and the nth error correction block have consecutive errors, the nth error correction block is excluded from the measurement target of the bit error rate; If the (n-1)th error correction block and the nth error correction block are not consecutively erroneous, include the nth error correction block in the measurement target of the bit error rate; the packets of one or more layers include upper packets constituting the highest layer, The known bits included in the header of the error correction block include at least a fixed value included in a bit string indicating the start position of the upper packet included in the error correction block.

2. 2. The measurement device according to claim 1, wherein, when the (n-1)th error correction block is not erroneous and the nth error correction block is erroneous, the measurement unit estimates the known bits included in the header of the nth error correction block based on the header of the upper packet included in the (n-1)th error correction block.

3. A receiving unit that receives a received signal including an error correction block in which one or more layers of packets are multiplexed; a measurement unit that measures a bit error rate of the received signal based on at least one of a known bit included in a header of the error correction block and a known bit included in a header of a packet of one or more layers, The measurement unit If the n-1th (n is an integer of 2 or more) error correction block and the nth error correction block have consecutive errors, the nth error correction block is excluded from the measurement target of the bit error rate; If the (n-1)th error correction block and the nth error correction block are not consecutively erroneous, include the nth error correction block in the measurement target of the bit error rate; the measurement unit measures a bit error rate of the received signal based on known bits included in a header of the error correction block and known bits included in headers of packets of the one or more layers; a measurement device in which, when the (n-1)th error correction block is not erroneous and the nth error correction block is erroneous, the measurement unit estimates the known bits included in the headers of the packets at one or more layers included in the nth error correction block based on the known bits included in the headers of the packets at one or more layers included in the (n-1)th error correction block.

4. A receiving unit that receives a received signal including an error correction block in which one or more layers of packets are multiplexed; a measurement unit that measures a bit error rate of the received signal based on at least one of a known bit included in a header of the error correction block and a known bit included in a header of a packet of one or more layers, The measurement unit If the n-1th (n is an integer of 2 or more) error correction block and the nth error correction block have consecutive errors, the nth error correction block is excluded from the measurement target of the bit error rate; If the (n-1)th error correction block and the nth error correction block are not consecutively erroneous, include the nth error correction block in the measurement target of the bit error rate; the measurement unit measures a bit error rate of the received signal based on known bits included in a header of the error correction block and known bits included in headers of packets of the one or more layers; The known bits included in the header of the packet include a bit string that indicates a type of the packet.

5. A receiving device comprising the measuring device according to claim 1.

6. A receiving device equipped with the measuring device described in claim 3.

7. A receiving device equipped with the measuring device described in claim 4.

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