JP2016076789A - Television broadcast system, transmitter, receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a television broadcast system capable of shortening the transition period from the previous generation.SOLUTION: A television broadcast system performing polarization MIMO transmission using a signal of first polarization and a signal of second polarization includes a transmitter transmitting the signal of first polarization and the signal of second polarization, where the signal of first polarization includes a signal for movement toward a movable receiver, the signal of first polarization and the signal of second polarization include a signal for fixing toward a receiver installed fixedly, a first receiver for receiving the signal of first polarization and the signal of second polarization, and decoding the signal for fixing, and a second receiver for receiving the signal of first polarization and decoding the signal for movement.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a television broadcasting system, a transmission device, and a reception device.

  The current terrestrial digital television broadcasting (ISDB-T (Integrated Services Digital Broadcasting Terrestrial)) transmits a fixed service and a mobile service on one channel. The method divides a frequency band of one channel into 13 segments by frequency division multiplexing, assigns each segment for fixed use and movement, and performs different modulation (see Non-Patent Document 1).

  On the other hand, next-generation digital terrestrial television broadcasting is being researched, and it is assumed that fixed and mobile services are transmitted by one channel as in the case of terrestrial digital television broadcasting. In addition, a polarization MIMO transmission system has been studied as a transmission method in next-generation digital terrestrial television broadcasting. In the current digital terrestrial television broadcasting, transmission is performed using one polarized wave. However, the polarization MIMO transmission system is a system that uses two different polarizations (for example, horizontal and vertical) on both the transmission side and the reception side and performs transmission using both polarizations simultaneously (non-transmission) Patent Document 2).

  In the MIMO transmission system, space division multiplexing (SDM) that expands transmission capacity by assigning different data to multiple transmit antennas and the same data with different encoding from multiple transmit antennas are transmitted. Thus, there is space-time multiplexing (STC) that improves transmission tolerance, and spatial multiplexing is being studied in next-generation terrestrial broadcasting.

"Transmission system standard for digital terrestrial television broadcasting ARIB STD-B31 2.2 version", Radio Industry Association, March 2014 Kenichi Murakami, “Next-generation terrestrial large-capacity transmission technology for Super Hi-Vision broadcasting”, NHK R & D, No. 134, July 2012

In many cases, the user can directly replace and install a receiving device such as a television receiver. On the other hand, when it is installed on the roof of a house, it is difficult for the user to directly install the antenna, and it is more frequently required by a specialized supplier than the receiving apparatus. For this reason, the transition period to the next generation digital terrestrial television broadcasting becomes longer when the antenna needs to be replaced than when only the receiving apparatus needs to be replaced. During the transition period, the broadcasting station must perform the next generation digital terrestrial television broadcast and the previous generation (ie, present) digital terrestrial television broadcast in parallel. For this reason, if a transition period becomes long, the burden on a broadcasting station will become large.
However, when the polarization MIMO method is adopted for next-generation terrestrial digital television broadcasting, it is necessary to change the antenna used to receive the current terrestrial digital television broadcast, which results in a long transition period. There is a problem.

  The present invention has been made in view of such circumstances, and provides a television broadcast system, a transmission device, and a reception device that can shorten the transition period from the previous generation.

(1) The present invention has been made to solve the above-described problems, and one aspect of the present invention is that polarization MIMO transmission using a first polarization signal and a second polarization signal is performed. A television broadcasting system to be performed, wherein the first polarization signal and the second polarization signal are transmitted, and the first polarization signal moves for a movable receiving device. And the first polarization signal and the second polarization signal include a transmission device including a fixed signal for a reception device that is fixedly installed, and the first polarization signal. A first receiving device that receives a wave signal and the second polarization signal and decodes the fixed signal; and receives the first polarization signal and decodes the movement signal A television broadcasting system including a second receiving device.

(2) According to another aspect of the present invention, there is provided the television broadcasting system according to (1), in which the second reception device includes the first polarization signal and the second polarization signal. Based on the fact that the first polarization signal and the second polarization signal are modulated by a predetermined modulation method, respectively, including a signal including an interference signal due to a wave signal. The maximum likelihood estimation of the signal of the first polarization is performed from the received signal.

(3) Another aspect of the present invention is the television broadcast system according to (1), in which the first polarized wave is used for broadcasting in the television broadcast system one generation before. It is characterized by being polarized.

(4) According to another aspect of the present invention, there is provided the television broadcasting system according to (1), in which the transmission device converts the fixing signal into a first fixing signal and a second fixing signal. A division unit that divides the first fixed signal and the moving signal, and a signal that is frequency-multiplexed by the synthesis unit using the first polarization. And a second sending unit for sending the second fixing signal using the polarized wave of the second polarization.

(5) According to another aspect of the present invention, there is provided a transmission apparatus in a television broadcasting system in which polarization MIMO transmission using a first polarization signal and a second polarization signal is performed. The first polarization signal and the second polarization signal are transmitted, and the first polarization signal includes a movement signal for a movable receiver, and the first polarization signal is transmitted to the first polarization signal. The wave signal and the second polarization signal include a fixed signal for a fixedly installed receiver.

(6) According to another aspect of the present invention, there is provided a receiving apparatus in a television broadcasting system in which polarization MIMO transmission using a first polarization signal and a second polarization signal is performed. A signal including the first polarization signal and an interference signal due to the second polarization signal is received, and the first polarization signal and the second polarization signal are: A receiving apparatus that performs maximum likelihood estimation of the signal of the first polarization from the received signal based on being modulated by a predetermined modulation method.

  According to the present invention, the transition period from the previous generation can be shortened.

It is a schematic block diagram which shows the structure of the television broadcasting system 1 by one Embodiment of this invention. It is the figure which showed the structural example of the signal which the transmitter 10 in the embodiment transmits. It is a block diagram which shows schematic structure of the transmitter 10 in the embodiment. It is the figure which showed the example of the schematic reception method by the 1st receiver 20 in the embodiment. It is a block diagram which shows schematic structure of the 1st receiver 20 in the embodiment. It is the figure which showed the example of the schematic reception method by the 2nd receiver 30 in the embodiment. It is a block diagram which shows schematic structure of the 2nd receiver 30 in the embodiment. It is the figure which showed the example of the schematic reception method by the 2nd receiver 30a in the modification of the embodiment. It is a block diagram which shows schematic structure of the 2nd receiver 30a in the modification of the embodiment. It is the graph which computed the receiving characteristic in the 2nd receiver 30 in the embodiment by computer simulation. It is a table | surface which shows the item of the computer simulation of the 2nd receiver 30 in the embodiment. It is the graph which computed the receiving characteristic in the 1st receiver 20 in the embodiment by computer simulation. It is a table | surface which shows the item of the computer simulation of the 1st receiver 20 in the embodiment. It is the graph which computed the receiving characteristic in the 2nd receiver 30a in the modification of the embodiment by computer simulation. It is a table | surface which shows the item of the computer simulation of the 2nd receiver 30a in the modification of the embodiment.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram showing the configuration of a television broadcast system 1 according to an embodiment of the present invention. The television broadcasting system 1 includes a fixing service for a receiving device fixedly installed such as a television receiver installed in a house, a television receiver installed in an automobile, a mobile phone, and the like. The mobile service for mobile receivers is transmitted using a polarization MIMO scheme in one channel. In the present embodiment, an example will be described in which, in an area where the television broadcast system 1 is constructed, the previous generation television broadcast system transmits a service using a horizontally polarized signal. .

  The television broadcast system 1 includes a transmission device 10, a first reception device 20, and a second reception device 30. The transmission device 10 uses a horizontally polarized antenna 111 and a vertically polarized antenna 112 to transmit a broadcast wave using a polarization MIMO scheme. That is, the transmission device 10 transmits a fixed service and a mobile service on one channel by transmitting a horizontally polarized signal and a vertically polarized signal. The service for movement is one in which the resolution (number of pixels) of the video for the fixed service is reduced or the frame rate is reduced. The resolution and the frame rate may be reduced.

  The first receiving device 20 is a receiving device that uses a horizontally polarized antenna 201 and a vertically polarized antenna 202 to receive and decode a fixed service signal. The second receiver 30 is a receiver that uses a horizontally polarized antenna 301 to receive and decode a mobile service signal. In an area where the television broadcast system 1 of the present embodiment is constructed, the previous generation television broadcast system uses a horizontally polarized signal. For this reason, in the second receiving apparatus 30, the antenna for receiving the previous generation television broadcasting system is installed as it is, and the antenna for receiving the polarization MIMO signal is not installed. Even so, the mobile service can be received by a receiving device that is fixedly installed.

  FIG. 2 is a diagram illustrating a configuration example of a signal transmitted by the transmission apparatus 10. In FIG. 2, the horizontal axis represents frequency, and one memory is one segment of ISDB-T. The transmission apparatus 10 allocates the movement service signal M1 (movement signal) to the two segments including the center frequency of the horizontally polarized signal. The transmitter 10 assigns fixed service signals P1, P2, and P3 (fixed signals) to the other 11 segments of horizontal polarization and 13 segments of vertical polarization. That is, only the fixed signal is assigned to the vertical polarization, and the movement signal is not transmitted in the vertical polarization.

  FIG. 3 is a block diagram illustrating a schematic configuration of the transmission device 10. The transmission apparatus 10 includes a layer separation unit 101, error correction code units 102 and 103, carrier modulation units 104 and 105, a division unit 106, a layer synthesis / frame unit 107, a frame unit 108, a transmission unit 109 and 110, A wave antenna 111 and a vertically polarized antenna 112 are included. The layer separation unit 101 separates an input signal into a movement signal and a fixed signal. In addition, the signal for movement and the signal for fixation which were produced | generated separately may be input without having the hierarchy separation part 101. FIG.

  The error correction coding unit 102 performs error correction coding on the movement signal using, for example, LDPC (Low-Density Parity-check Code). The error correction coding unit 103 performs error correction coding on the fixing signal. The carrier modulation unit 104 performs carrier modulation on the movement signal that has been error correction encoded by the error correction encoding unit 102 using a predetermined modulation method such as QPSK (Quaternary Phase Shift Keying). The carrier modulation unit 105 performs carrier modulation on the fixed signal that has been error correction encoded by the error correction encoding unit 103 using a predetermined modulation method such as 64QAM (Quadrature Amplitude Modulation). The modulation scheme used in carrier modulation sections 104 and 105 may be selected from a plurality of predetermined modulation schemes.

  The dividing unit 106 divides the fixed signal carrier-modulated by the carrier modulating unit 105 into 11 segments and 13 segments. Hierarchical combining / framing section 107 is an OFDM (Orthogonal Frequency Division Multiplexing) frame in which the 11 segments divided by dividing section 106 and the moving signal carrier-modulated by carrier modulating section 104 are hierarchically combined by frequency multiplexing. Is generated. The framing unit 108 generates OFDM frames for 13 segments divided by the dividing unit 106.

  The sending unit 109 performs inverse fast Fourier transform, guard interval insertion, digital / analog conversion, up-conversion to a radio frequency, and the like on the OFDM frame generated by the layer synthesis / framing unit 107, for horizontal polarization. Generate a radio signal. The transmission unit 110 performs inverse fast Fourier transform, guard interval insertion, digital / analog conversion, up-conversion to a radio frequency, and the like on the OFDM frame generated by the framing unit 108, and converts the radio signal for vertical polarization into Generate. The antenna 111 transmits the radio signal generated by the transmission unit 109 mainly by a horizontally polarized radio wave. The antenna 112 transmits the radio signal generated by the transmission unit 110 mainly by vertically polarized radio waves.

  FIG. 4 is a diagram illustrating an example of a schematic reception method by the first reception device 20. The first receiving device 20 that receives and decodes the fixed signal receives the two polarized signals transmitted from the antennas 111 and 112 of the transmitting device 10 and decodes the fixed signal by the antennas 201 and 202, respectively. . Note that the solid-line transmission path shown in FIG. 4 is a transmission path in which the direction of polarization characteristics of the antenna is the same on the transmission side and the reception side, and the transmission path indicated by a broken line is the transmission path of the antenna on the transmission side and the reception side. This is a transmission line with different polarization characteristics. For example, the transmission path from the antenna 111 to the antenna 201 is a transmission path having the same direction of the polarization characteristics of the antenna, and the transmission path from the antenna 112 to the antenna 201 is a transmission having a different direction of the polarization characteristics of the antenna. Road. The larger the XPD (cross polarization discrimination degree) of each antenna, the better the reception characteristics, but it is not infinite. Therefore, even if the direction of the polarization characteristics differs from that of the antenna 112, the antenna 201 is different from the antenna 112. The signal is received. However, when the antenna 201 receives a signal from the antenna 112, the radio path loss becomes larger than when the antenna 201 receives a signal from the antenna 111 having the same polarization characteristic direction.

  FIG. 5 is a block diagram illustrating a schematic configuration of the first receiving device 20. The first receiving device 20 includes antennas 201 and 202, radio receiving units 203 and 204, transmission path estimation units 205 and 206, a decoding unit 207, and an error correction code unit 208. The antenna 201 mainly receives a horizontally polarized signal. The antenna 202 mainly receives a vertically polarized signal. The wireless reception unit 203 down-converts the signal received by the antenna 201 to a baseband frequency, and then performs analog / digital conversion, guard interval removal, and Fourier transform (OFDM demodulation). The radio reception unit 204 down-converts the signal received by the antenna 202 to a baseband frequency, and then performs analog / digital conversion, removal of guard intervals, and Fourier transform (OFDM demodulation).

  The transmission path estimation unit 205 estimates the transmission path from the antenna 111 to the antenna 201 and from the antenna 112 to the antenna 201 from the signal demodulated by the radio reception unit 203. The transmission path estimation unit 206 estimates the transmission path from the antenna 111 to the antenna 202 and from the antenna 112 to the antenna 202 from the signal demodulated by the radio reception unit 204. Decoding section 207 decodes each bit value of the fixed signal from the signals demodulated by OFDM by radio receiving sections 203 and 204 using the transmission paths estimated by transmission path estimation 205 and 206. As a decoding method of the decoding unit 207, any of zero forcing (ZF), maximum likelihood estimation, least square method (MMSE), or the like may be used. The error correction decoding unit 208 performs error correction decoding on each bit value of the fixing signal decoded by the decoding unit 207.

  FIG. 6 is a diagram illustrating an example of a schematic reception method by the second reception device 30. The second reception device 30 that receives and decodes the movement signal receives the two polarized signals transmitted from the antennas 111 and 112 of the transmission device 10 by the antenna 301 and decodes the movement signal. Note that the solid transmission line shown in FIG. 6 is a transmission line in which the direction of the polarization characteristics of the antenna is the same on the transmission side and the reception side, and the transmission line indicated by a broken line is the transmission line of the antenna on the transmission side and the reception side. This is a transmission line with different polarization characteristics. The transmission path from the antenna 111 to the antenna 301 is a transmission path having the same direction of the polarization characteristics of the antenna, and the transmission path from the antenna 112 to the antenna 301 is a transmission path having a different direction of the polarization characteristics of the antenna. is there. Similar to the case described with reference to FIG. 4, the antenna 301 receives the signal from the antenna 112 as an interference signal with respect to the signal from the antenna 111, even if the direction of the polarization characteristic is different from that of the antenna 112.

  FIG. 7 is a block diagram illustrating a schematic configuration of the second receiving device 30. The second receiving device 30 includes an antenna 301, a radio receiving unit 302, a transmission path estimation unit 303, a maximum likelihood estimation unit 304, and an error correction decoding unit 305. The antenna 301 mainly receives a horizontally polarized signal. The radio reception unit 302 down-converts the signal received by the antenna 301 to a baseband frequency, and then performs analog / digital conversion, guard interval removal, and Fourier transform (OFDM demodulation).

  The transmission path estimation unit 303 transmits the transmission path from the antenna 111 to the antenna 301 and the transmission path from the antenna 112 to the antenna 301 from the signal of the segment to which the movement signal is allocated among the signals demodulated by the radio reception unit 302. Is estimated. The segments to which the movement signal is assigned are determined in advance, and in this embodiment, are the two segments to which the movement signal M1 shown in FIG. 2 is assigned.

  The maximum likelihood estimation unit 304 uses the transmission path estimated by the transmission path estimation 303 to determine the movement signal from the signal of the segment to which the movement signal is allocated among the signals demodulated by the radio reception unit 302 by OFDM. Maximum likelihood estimation of each bit value. The maximum likelihood estimation unit 304 modulates this maximum likelihood estimation using signals determined by the antenna 111 and the signal from the antenna 112, which is an interference signal, among the signals received by the antenna 301, using a predetermined modulation method. To do that. The details of the method of maximum likelihood estimation by the maximum likelihood estimation unit 304 will be described later. The error correction decoding unit 305 performs error correction decoding on each bit value of the fixed signal estimated by the maximum likelihood estimation unit 304.

Next, a method of maximum likelihood estimation by the maximum likelihood estimation unit 304 will be described. Of the signals OFDM demodulated by the wireless reception unit 302, the segment signal to which the movement signal is assigned is denoted by r. Further, in the segment to which the signal for movement is allocated, the signal transmitted from the antenna 111 is x, the signal transmitted from the antenna 112 is y, the transmission path from the antenna 111 to the antenna 301 is h ₁ , and the antenna 112 is connected. transmission paths to the antenna 301 and _{h 2.} If the addition of noise is omitted, the relational expression between them can be expressed by equation (1).

Since r is obtained by the radio reception unit 302 and h ₁ and h ₂ are estimated by the transmission path estimation unit 303, the equation (2) is used for each bit of the movement signal using these values. The value with the smallest absolute value of the likelihood value LLR represented by () is calculated as follows. In Equation (2), σ ² is a noise variance value, which is obtained when a transmission path is estimated.

  Here, a case will be described as an example where QPSK is used as the modulation method for the movement signal and 64QAM is used for the modulation method for the fixed signal. First, the maximum likelihood estimation unit 304, when the first bit of the signal x transmitted from the antenna 111 is “0”, is a value (modulation symbol) that can be taken when the value that the signal x can take is modulated by QPSK. ) To choose from. QPSK has four modulation symbols, and two of them have the first bit of “0”. The maximum likelihood estimation unit 304 substitutes either of these two values for x in the equation (2), and substitutes any of the 64 values that can be taken when modulated by 64QAM for y in the equation (2). Then, the likelihood value LLR is calculated.

The maximum likelihood estimation unit 304 substitutes all combinations of possible values for x and y into Equation (2) to calculate a likelihood value LLR. Here, since there are two substitutable values for x and there are 64 substitutable values for y, there are 128 combinations of 2 × 64 substitutable values. The maximum likelihood estimation unit 304 extracts the likelihood value LLR having the smallest absolute value from the likelihood values LLR calculated for these 128 combinations and sets it as the likelihood value LLR ₀ .

Next, the maximum likelihood estimation unit 304 assigns all combinations of possible values for x and y to Expression (2) even when the first bit of the signal x transmitted from the antenna 111 is “1”. Then, the likelihood value LLR is calculated. Even when the first bit of the signal x is “1”, since there are 128 combinations, the maximum likelihood estimation unit 304 has the smallest absolute value among the likelihood values LLR calculated for these 128 combinations. A thing is extracted and set to a likelihood value LLR ₁ .

The maximum likelihood estimation unit 304 compares the likelihood value LLR ₀ and the likelihood value LLR ₁ , and when the likelihood value LLR ₀ is smaller, estimates the first bit of the signal x as “0” and vice versa. When the likelihood value LLR ₁ is smaller, the first bit of the signal x is estimated as “1”. The bit values are estimated in the same manner for the second and subsequent bits of the signal x. Note that the maximum likelihood estimation unit 304 may calculate a soft decision value instead of the bit hard decision value.

[Modification]
In the first embodiment, the television broadcasting system 1 has the second receiving device 30 having only one antenna (antenna 301) as a receiving device that receives a movement signal. The second receiving device 30a having a plurality of horizontally polarized antennas, such as a receiving device mounted on the mobile phone, may be included.

  FIG. 8 is a diagram illustrating an example of a schematic reception method by the second reception device 30a. The second reception device 30a that receives and decodes the movement signal receives the two polarized signals transmitted from the antennas 111 and 112 of the transmission device 10 by the two antennas 301, and decodes the movement signal. Note that the solid-line transmission path shown in FIG. 8 is a transmission path in which the direction of polarization characteristics of the antenna is the same on the transmission side and the reception side, and the transmission path indicated by a broken line is the transmission path of the antenna on the transmission side and the reception side. This is a transmission line with different polarization characteristics. The transmission path from the antenna 111 to each of the antennas 301 is a transmission path having the same direction of the polarization characteristics of the antenna, and the transmission path from the antenna 112 to each of the antennas 301 has a different direction of the polarization characteristics of the antenna. Road. As in the case described with reference to FIG. 4, each antenna 301 receives a signal from the antenna 112 as an interference signal with respect to the signal from the antenna 111 even if the direction of the polarization characteristic is different from that of the antenna 112. .

  FIG. 9 is a block diagram illustrating a schematic configuration of the second receiving device 30a. In the figure, the same reference numerals (301 to 303, 305) are assigned to portions corresponding to the respective portions in FIG. The second receiver 30a includes two antennas 301, two radio receivers 302, two transmission path estimators 303, a maximum likelihood estimator 304a, and an error correction decoder 305. The maximum likelihood estimation unit 304a uses the transmission path estimated by the two transmission path estimations 303, from the signals of the segment to which the signal for movement is allocated among the signals demodulated by the two radio reception units 302, Maximum likelihood estimation is performed on each bit value of the movement signal. The maximum likelihood estimation unit 304a performs this maximum likelihood estimation from the signals received from the antennas 111 and the antenna 112, which is an interference signal, among the signals received by each antenna 301, as in the maximum likelihood estimation unit 304 of FIG. This is performed based on the fact that each signal is modulated by a predetermined modulation method.

Of the signals demodulated by the OFDM by the two wireless reception units 302, the signals of the segments to which the movement signal is assigned are denoted by r ₁ and r ₂ , respectively. Further, in the segment to which the signal for movement is allocated, the signal transmitted from the antenna 111 is x, the signal transmitted from the antenna 112 is y, and the transmission path from the antenna 111 to each antenna 301 is represented by h. ₁ , h ₃ , and transmission paths from the antenna 112 to each antenna 301 are denoted by h ₂ and h ₄ , respectively. If the addition of noise is omitted, the relational expression between them can be expressed by equations (3) and (4).

r ₁ and r ₂ are obtained by each radio reception unit 302, and h ₁ , h ₂ , h ₃ , and h ₄ are estimated by each transmission path estimation unit 303. The maximum likelihood estimator 304a uses these values to calculate the likelihood value LLR represented by the equation (5) for each bit of the movement signal, and similarly to the maximum likelihood estimator 304, Get the value of each bit.

  FIG. 10 is a graph in which the reception characteristics in the second receiver 30 are calculated by computer simulation. In this simulation, QPSK is assigned to the movement signal and 64QAM is assigned to the fixed signal. The specifications of the simulation are shown in FIG. FIG. 10 shows C / N (carrier power to noise power ratio) on the horizontal axis and BER (bit error rate) characteristics on the vertical axis. The broken line labeled “64QAM-QPSK MLD DU = 10 dB” is the BER characteristic of the mobile signal reception by the second receiving device 30 when the XPD of the antenna 301 is 10 dB. A broken line labeled “64QAM-QPSK MLD DU = 20 dB” is a BER characteristic of signal reception for movement by the second receiving device 30 when the XPD of the antenna 301 is 20 dB. A dotted line labeled “QPSK SISO” is a BER characteristic of QPSK-SISO transmission. Thus, if the XPD of the antenna 301 is about 20 dB, a BER characteristic comparable to “QPSK SISO” used by One Seg in the current terrestrial digital television broadcasting can be obtained.

  FIG. 12 is a graph in which the reception characteristics in the first receiving device 20 are calculated by computer simulation. The specifications of the simulation are shown in FIG. This simulation uses QPSK for the movement signal and 64QAM for the fixed signal. The broken line labeled “64QAM-QPSK ZF DU = 10 dB” in FIG. 12 is the BER characteristic of the mobile signal reception by the first receiver 20 when the XPD of the antennas 201 and 202 is 10 dB.

  Further, the broken line labeled “64QAM-QPSK ZF DU = 20 dB” is the BER characteristic of the signal reception for movement by the first receiving device 20 when the XPD of the antennas 201 and 202 is 20 dB. Further, the graph of “MIMO 64QAM ZF” shows characteristics when 64QAM is transmitted by general 2 × 2 MIMO transmission. From this result, it can be confirmed that the transmission characteristics are not deteriorated as compared with the conventional case.

  FIG. 14 is a graph in which the reception characteristics in the second receiver 30a are calculated by computer simulation. The specifications of the simulation are shown in FIG. In this simulation, QPSK is assigned to the movement signal and 64QAM is assigned to the fixed signal. The wavy line labeled “64QAM-QPSK MLD DU = 10 dB” in FIG. 14 is the BER characteristic of the moving signal reception by the second receiving device 30a when the XPD of the receiving antenna is 10 dB. Further, the graph of “MIMO-QPSK MLD DU = 10 dB” shows the characteristics when QPSK is transmitted by general 2 × 2 MIMO transmission. It can be seen from the figure that the characteristics of the second receiving device 30a are improved when C / N = 20 dB or less. When C / N = 20 dB or more, the characteristics deteriorate, but it can be expected that the characteristics in this range are error-free by applying an error correction code (FEC) to this simulation. Since an error correction code is an indispensable technique in an actual system, this result can be applied to the system in an area where the proposed method is excellent. Therefore, the second receiving device 30a can improve the reception characteristics when receiving the signal for movement with the two antennas.

In the above-described embodiment, since the previous generation television broadcasting system uses horizontal polarization as an example, the mobile service is transmitted using a horizontally polarized signal. However, when the previous generation television broadcasting system uses vertical polarization, the mobile service is transmitted using the vertical polarization signal.
In addition, it is desirable that the polarization used by the previous generation television broadcasting system and the polarization used by the mobile service match, but they may be different. This is because switching between vertical polarization and horizontal polarization of the antenna can be handled simply by changing the direction in which the antenna is installed, so it is easier than replacing the antenna and shortens the transition period. Because it can.
The television broadcast system 1 may be another wireless communication system such as an audio broadcast system.

  Further, a program for realizing the functions of the transmission device 10, the first reception device 20, the second reception device 30 in FIG. 1 or the second reception device 30a in FIG. 9 is recorded on a computer-readable recording medium, Each apparatus may be realized by causing a computer system to read and execute a program recorded on the recording medium. Here, the “computer system” includes an OS and hardware such as peripheral devices.

Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used.
The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case, and a program that holds a program for a certain period of time are also included. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

In addition, each functional block of the transmission device 10 in FIG. 1, the first reception device 20, the second reception device 30, or the second reception device 30a in FIG. All may be integrated into a chip. Further, the method of circuit integration is not limited to LSI, and implementation using a dedicated circuit or a general-purpose processor is also possible. Either hybrid or monolithic may be used. Some of the functions may be realized by hardware and some by software.
In addition, when a technology such as an integrated circuit that replaces an LSI appears due to progress in semiconductor technology, an integrated circuit based on the technology can be used.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like within a scope not departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Television broadcasting system 10 ... Transmitting device 20 ... 1st receiving device 30, 30a ... 2nd receiving device 101 ... Hierarchy separation part 102, 103 ... Error correction encoding part 104, 105 ... Carrier modulation part 106 ... Dividing part 107 ... Hierarchical synthesis / framing unit 108 ... Framing unit 109, 110 ... Sending unit 111, 112 ... Antenna 201, 202 ... Antenna 203, 204 ... Radio receiving unit 205, 206 ... Transmission path estimation unit 207 ... Decoding unit 208 ... Error correction Decoding unit 301 ... Antenna 302 ... Wireless receiving unit 303 ... Transmission path estimation unit 304, 304a ... Maximum likelihood estimation unit 305 ... Error correction decoding unit

Claims (6)

A television broadcast system in which polarization MIMO transmission using a first polarization signal and a second polarization signal is performed,
The first polarization signal and the second polarization signal are transmitted, and the first polarization signal includes a movement signal for a movable receiver, and the first polarization signal is transmitted to the first polarization signal. The wave signal and the second polarization signal include a fixed signal for a fixedly installed receiver; and
A first receiver for receiving the first polarization signal and the second polarization signal and decoding the fixed signal;
A television broadcasting system comprising: a second receiving device that receives the first polarization signal and decodes the movement signal. The second receiving device is:
Receiving a signal including the first polarization signal and an interference signal generated by the second polarization signal;
Based on the fact that the first polarization signal and the second polarization signal are respectively modulated by a predetermined modulation method, from the received signal, the first polarization signal The television broadcasting system according to claim 1, wherein maximum likelihood estimation of the signal is performed.   The television broadcast system according to claim 1, wherein the first polarization is a polarization used for broadcasting in the television broadcast system of the previous generation. The transmitter is
A dividing unit for dividing the fixing signal into a first fixing signal and a second fixing signal;
A synthesizer for frequency-multiplexing the first fixed signal and the moving signal;
A first sending unit for sending the frequency-multiplexed signal by the combining unit using the first polarization;
The television broadcasting system according to claim 1, further comprising: a second sending unit that sends the second fixing signal using the polarization of the second polarization. A transmission apparatus in a television broadcasting system in which polarization MIMO transmission using a first polarization signal and a second polarization signal is performed,
The first polarization signal and the second polarization signal are transmitted, and the first polarization signal includes a movement signal for a movable receiver, and the first polarization signal is transmitted to the first polarization signal. The wave signal and the second polarization signal include a fixed signal for a receiving device that is fixedly installed. A receiving apparatus in a television broadcasting system in which polarization MIMO transmission using a first polarization signal and a second polarization signal is performed,
Receiving a signal including the first polarization signal and an interference signal generated by the second polarization signal;
Based on the fact that the first polarization signal and the second polarization signal are respectively modulated by a predetermined modulation method, from the received signal, the first polarization signal A receiver characterized by performing maximum likelihood estimation of a signal.

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