JP5286091B2 - Spatial multiplexing transmission adapter and spatial multiplexing transmission receiver adapter - Google Patents

Description

  The present invention relates to a spatial multiplexing transmission adapter that uses a plurality of non-spatial multiplexing type radio transmission apparatuses and spatially multiplexes them to the same frequency channel for transmission.

  MIMO (Multi-Input Multi-Output) is a technique in which a plurality of antennas are used on both the transmission side and the reception side, and signals are spatially multiplexed and transmitted on a radio propagation path between the plurality of antennas. This spatial multiplexing communication by MIMO has the advantage of dramatically improving the transmission capacity, and has effects such as high-speed transmission and improved communication quality. In this MIMO technology, pilot signals inserted so as to be orthogonal codes are used for separating and detecting a plurality of transmission streams multiplexed in the spatial domain (see, for example, Patent Document 1).

  As described above, in the MIMO scheme, it is necessary to match the transmission timing of each transmission stream and insert a pilot signal so as to obtain an orthogonal code. Therefore, the existing technology develops and manufactures a transmission device for spatial multiplexing transmission. It will be.

  On the other hand, as a system for transmitting program material from a relay site to a broadcasting station or the like, an OFDM (orthogonal frequency division multiplexing) digital wireless transmission system is summarized as the ARIB STD-B33 standard (see, for example, Non-Patent Document 1). .

  Combining MIMO technology (referred to as MIMO-OFDM) with this OFDM broadcast radio transmission apparatus (referred to as OFDM-FPU transmission apparatus) is being studied, and by using this, the frequency utilization efficiency will be dramatically improved. It is expected to improve.

JP 2005-124125 A

"Portable OFDM digital wireless transmission system for transmitting TV broadcast program material" ARIB STD-B33

  However, in order to realize spatial multiplexing transmission, it is necessary to insert pilot signals that are orthogonal codes in each transmission stream in order to estimate propagation channel characteristics, and it is necessary to match transmission timing so that orthogonality can be maintained. For this reason, the conventional technology needs to be developed and manufactured as a transmission device dedicated to spatial multiplexing.

  Furthermore, it is not realistic to update existing facilities deployed at each broadcasting station, such as OFDM-FPU transmission devices, to new spatial multiplexing transmission devices that can effectively use finite frequency resources. There is a problem.

  Also, spatial multiplexing transmission is not universal, and a propagation environment with few multipaths is not suitable for spatial multiplexing transmission. Therefore, in such a propagation environment, it is necessary to use a conventional wireless transmission facility of non-spatial multiplexing type such as frequency division multiplexing. That is, it is desirable to use the spatial multiplexing method and the non-spatial multiplexing method properly according to the propagation environment and purpose.

  Accordingly, an object of the present invention is to provide a transmission adapter and a reception adapter that can be used in existing wireless transmission facilities and selectively realize spatial multiplexing transmission.

The above-mentioned problem of the present invention is an adapter that is used in combination with a non-spatial multiplexing type radio transmission apparatus, and that adapts the radio transmission apparatus to spatial multiplexing transmission. An adapter that inputs a plurality of IF signals and outputs a plurality of IF signals modulated by the MIMO-OFDM method, and demodulates the input non- spatial multiplexed IF signal to restore the OFDM frame A demodulator, a transmission system synchronization unit that synchronizes the OFDM frames of each system, and a CP that inverts the pilot signals so that the pilot signals of the symbols constituting the OFDM frames of each system have orthogonal codes. A code inverting unit, and a remodulating unit that remodulates the OFDM frame that has been code-inverted by the CP code inverting unit. It is solved by spatial multiplexing transmission for transmission adapter to symptoms.

  In addition, it is desirable that the spatial multiplexing transmission adapter further includes a carrier exchange unit between the transmission system synchronization unit and the CP code inversion unit.

Here, the spatial multiplexing transmission for transmission adapter, the carrier exchange unit, it is considered the a method for exchanging between the transmit line over all symbols Some carrier of each symbol constituting the OFDM frame It is done.

Here, in the above-described transmission adapter for spatial multiplexing transmission, it is conceivable that the carrier exchange unit is a system in which all carriers other than the pilot signal are exchanged between transmission systems at a certain symbol timing.

  Further, in the transmission adapter for spatial multiplexing transmission, the outputted multiple systems of IF signals are input to a transmission RF section including a plurality of systems of up-converters whose timing is controlled by a common local oscillator, and the transmission RF section Converts the output IF signals of a plurality of systems into RF signals and transmits them on the same frequency channel.

  Further, in the above-described transmission adapter for spatial multiplexing transmission, it is conceivable that the plurality of input IF signals are IF signals obtained by performing transmission path decoding on different TS signals.

  In addition, it is conceivable that the above-described transmission adapter for spatial multiplexing transmission is an IF signal obtained by performing transmission path decoding after distributing one TS signal.

Also, it is an adapter that is used in combination with a non-spatial multiplex type radio receiving apparatus, and that adapts the radio receiving apparatus to spatial multiplex transmission, and inputs OFDM signals of a plurality of systems modulated by the MIMO-OFDM system. An adapter that outputs a plurality of systems of IF signals modulated by the receiver to the reception control unit of the wireless receiver , each demodulating unit that demodulates an input spatially multiplexed IF signal to restore an OFDM frame, and A receiving system synchronization unit that synchronizes the OFDM frame of the system, a signal separation unit that performs signal separation based on orthogonality of pilot signals in the OFDM frame, and each symbol that constitutes the OFDM frame separated by the signal separation unit The pilot code of the pilot signal is inverted by the CP code inversion unit that inverts the sign of the pilot signal. A re-modulating unit that re-modulates the inverted OFDM frame, and the CP code inverting unit performs code inverting so as to return to the original code before code inverting at the transmitting side. It is also solved by the receiving adapter.

  The spatial multiplexing transmission receiving adapter may further include a carrier exchange unit between the signal separation unit and the CP code inversion unit.

  Here, it is conceivable that the spatial multiplexing transmission reception adapter is a system in which the carrier exchange unit exchanges some carriers of each symbol constituting the OFDM frame between reception systems over all symbols.

In addition, in the receiving adapter for spatial multiplexing transmission, it is conceivable that the carrier exchange unit is a system in which all carriers other than the pilot signal are exchanged between reception systems at a certain symbol timing.

  Further, in the receiving adapter for spatial multiplexing transmission, it is conceivable that the output multiple-system IF signals are independently decoded in each system and converted into independent TS signals.

  In the spatial multiplexing transmission receiving adapter, it is conceivable that the plurality of output IF signals are subjected to transmission path decoding independently in each system and then combined into one TS signal.

  By using the spatial multiplexing transmission adapter according to the present invention, it is possible to realize spatial multiplexing transmission using a conventional non-spatial multiplexing wireless transmission apparatus. In addition, since the conventional wireless transmission device is used without modification, the non-spatial multiplex transmission method and the spatial multiplex transmission method can be used properly according to the propagation environment.

It is explanatory drawing of the transmission system of the conventional frequency division multiplex transmission system. It is explanatory drawing of the transmission system using the adapter for space multiplexing transmission. Example 1 It is a block diagram explaining the process of the transmission adapter for spatial multiplexing transmission. Example 1 It is a block diagram explaining the process of the receiving adapter for spatial multiplexing transmission. Example 1 It is a layout diagram of pilot signals based on the ARIB STD-B33 standard. FIG. 5 is a layout diagram of pilot signals for sign inversion. It is a block diagram explaining the process of the transmission adapter for spatial multiplexing transmission. (Example 2) It is a block diagram explaining the process of the receiving adapter for spatial multiplexing transmission. (Example 2) It is explanatory drawing of the space interleaving by carrier exchange. (Example 1) It is explanatory drawing of the space interleaving by carrier exchange. (Example 2) It is explanatory drawing of the transmission system using the adapter for space multiplexing transmission. (Example 3)

  For comparison with the embodiment of the present invention, a conventional frequency division multiplexing transmission system will be described first. Here, an FPU (Field Pickup Unit) transmission system compliant with the ARIB STD-B33 standard for radio equipment for broadcasting material transmission will be described as an example.

  The frequency division multiplex transmission system transmission system shown in FIG. 1 transmits signals from two transmitters (1a, 1b) to two receivers (2a, 2b) via two frequency channels (Ch1, Ch2). This is a system for transmitting (S1, S2).

  The two transmission devices (1a, 1b) include a camera (3a, 3b), an encoder (ENC; 4a, 4b), a transmission control unit (5a, 5b), a transmission RF unit (6a, 6b), and a transmission antenna (7a, 7b).

  The cameras (3a, 3b) take a subject and acquire video information. The encoder (ENC; 4a, 4b) encodes the acquired video information and outputs a TS signal to the transmission control unit (5a, 5b) in a TS (Transport Stream) format. The transmission control units (5a, 5b) perform transmission path coding on the input TS signal and output an IF signal (intermediate frequency signal). The transmission RF unit (6a, 6b) frequency-converts the input IF signal into an RF signal (high frequency signal), further amplifies the power, and outputs the result to the transmission antenna (7a, 7b). Thereafter, the signal S1 and the signal S2 are transmitted from the transmission antenna 7a and the transmission antenna 7b through the frequency channel Ch1 and the frequency channel Ch2, respectively.

  Note that the transmission path coding in the transmission control units (5a, 5b) referred to here includes not only OFDM modulation but also signal processing such as error correction coding and interleaving as standardized by ARIB STD-B33. Refers to processing that includes.

  The two receiving devices (2a, 2b) include a receiving antenna (8a, 8b), a receiving RF unit (9a, 9b), a receiving control unit (10a, 10b), a decoder (DEC; 11a, 11b), and a monitor (12a). , 12b).

  The reception RF units (9a, 9b) frequency-convert the RF signals input via the reception antennas (8a, 8b) into IF signals, and output the IF signals to the reception control units (10a, 10b). The reception control unit (10a, 10b) performs transmission path decoding on the input IF signal, and outputs the transmission path decoded TS signal to the decoder (11a, 11b). The decoder (11a, 11b) decodes the TS signal and outputs the obtained video information to the monitor (12a, 12b).

  Note that the transmission path decoding in the reception control unit referred to here means processing including not only OFDM demodulation but also signal processing such as error correction and deinterleaving as standardized by ARIB STD-B33. .

The transmission system from the two transmission devices (1a, 1b) configured as described above to the two reception devices (2a, 2b) transmits signals (S1, S2) via two different frequency channels (Ch1, Ch2). Since S2) is transmitted, interference at the radio frequency can be avoided. However, there is a demerit that more radio frequency is consumed when trying to transmit more signals.
[Example 1]

  FIG. 2 is a diagram for explaining a transmission apparatus 1 and a reception apparatus 2 in which the spatial multiplexing transmission adapter 13 and the spatial multiplexing transmission adapter 14 according to the present invention are applied to a transmission system compliant with the ARIB STD-B33 standard. .

  As shown in FIG. 2, the spatial multiplexing transmission system of the present embodiment is changed from a transmitting apparatus 1 having two transmitting antennas (7a, 7b) to a receiving apparatus 2 having two receiving antennas (8a, 8b). In this system, different signals (S1, S2) are transmitted through the same frequency channel Ch1.

  The transmission apparatus 1 using the spatial multiplexing transmission adapter 13 according to the present invention includes a camera (3a, 3b), an encoder (4a, 4b), a transmission control unit (5a, 5b) as components common to existing apparatuses. A transmission antenna (7a, 7b) is provided, and a spatial multiplexing transmission adapter 13 and a transmission RF unit 6 are further provided as newly added components.

  On the other hand, the receiving device 2 using the receiving adapter 14 for spatial multiplexing transmission according to the present invention has a receiving antenna (8a, 8b), a receiving RF unit (9a, 9b), and a receiving control unit (10a) as common components with the existing device. , 10b), decoders (11a, 11b) and monitors (12a, 12b), and a spatial multiplexing transmission receiving adapter 14 as a newly added component.

  The cameras (3a, 3b), the encoders (4a, 4b), and the transmission control units (5a, 5b), which are common parts with the existing apparatus, encode the acquired video information and the transmission path encoding as in the conventional case. 2 outputs IF signals.

  However, it is assumed that the parameters related to transmission such as the modulation scheme and error correction scheme in the transmission control units (5a, 5b) in the above configuration are the same, and the TMCC control information is also the same.

  The two systems of IF signals obtained with the above configuration are input to the spatial multiplexing transmission adapter 13, perform signal processing for spatial multiplexing, and output two systems of IF signals. The internal processing of the spatial multiplexing transmission adapter 13 will be described later with reference to FIG.

  The two systems of IF signals output from the spatial multiplexing transmission adapter 13 are input to the transmission RF unit 6. At this time, it should be noted that one transmission RF unit 6 is shared with respect to two systems of IF signals. Here, although the internal configuration diagram of the transmission RF unit 6 is omitted, the two systems of IF signals are frequency-converted by the two systems of up-converters. However, these two systems of up-converters are timing-controlled by a common local oscillator. Thus, the frequency-converted RF signal can be transmitted on the same frequency channel with no frequency deviation.

  Further, the transmission RF unit 6 amplifies the power of the frequency-converted RF signal and then transmits the signals (S1, S2) by the respective transmission antennas (7a, 7b).

  The signals (S1, S2) transmitted on the same frequency channel are received by two different receiving antennas (8a, 8b). At this time, since the signals (S1, S2) are transmitted through the same frequency channel, the reception antennas (8a, 8b) receive the RF signal in which the two signals (S1, S2) are multiplexed.

  The RF signals received by the receiving antennas (8a, 8b) are frequency-converted into IF signals by the receiving RF units (9a, 9b). Unlike the transmission RF unit 6, the reception RF unit (9a, 9b) does not need to include a down converter whose timing is controlled by a common local oscillator. This is because, on the reception side, synchronization can be achieved by correcting the frequency deviation generated between the reception systems in the spatial multiplexing transmission reception adapter 14.

  The IF signal obtained by frequency conversion is input to the spatial multiplexing transmission reception adapter 14. The spatial multiplexing transmission reception adapter 14 separates signals multiplexed in the spatial domain and outputs two systems of IF signals. The internal processing of the spatial multiplexing transmission reception adapter 14 will be described later with reference to FIG.

  The two systems of IF signals output from the spatial multiplexing transmission reception adapter 14 are respectively input to reception control units (10a, 10b) that are common to existing FPUs. Further, the data is sequentially transferred to the decoder (11a, 11b) and the monitor (12a, 12b).

  Here, the internal processing of the spatial multiplexing transmission adapter 13 will be described with reference to the block diagram of FIG. Although not shown in the figure, symbol synchronization and frequency synchronization are established in each transmission system.

  Analog-to-digital conversion (A / D; 15a, 15b), quadrature demodulation (16a, 16b), low-pass filtering by simultaneous sampling, respectively, to the two systems of IF signals input from the transmission control unit (5a, 5b) (LPF; 17a, 17b), guard interval (GI) removal (18a, 18b), and fast Fourier transform (FFT; 19a, 19b) are sequentially performed. By these signal processing, the OFDM frame is restored from the analog IF signal. In other words, the series of signal processing functions as a partial demodulation unit 36 for channel coding.

  Next, the frame head detector (20a, 20b) detects the TMCC control signal from the output of the fast Fourier transform (FFT; 19a, 19b), and reads the synchronization word of the OFDM frame. Using this synchronization word, the frame head of the OFDM frame is detected.

  Thereafter, in the symbol buffer units (21a, 21b), the signal is delayed in OFDM symbol units so that the heads of the detected frames coincide in each transmission system. This makes it possible to perform spatial multiplexing transmission by synchronizing symbols in each transmission system.

  Next, the CP code inversion unit 22 performs code inversion so that pilot signals (CP: Continuous Pilot) of each system become orthogonal codes. Since the pilot signals of each transmission system modulated by the OFDM method have the same value and are not orthogonal codes, propagation channel characteristics between a plurality of transmitting and receiving antennas cannot be estimated on the receiving side, and as a result, spatially multiplexed The signal cannot be separated or detected. For this reason, the transmission adapter for spatial multiplexing transmission according to the present invention includes the CP code inversion unit, thereby performing an operation of switching the pilot signals so as to be orthogonal codes.

  Here, a specific example of the sign inversion of the pilot signal in the present embodiment will be described with reference to FIGS. In the ARIB STD-B33 standard to which this embodiment complies, one CP carrier is inserted every eight in the carrier direction, and a pilot signal that is always BPSK modulated with the same value is inserted in this carrier. (See FIG. 5).

  Since this embodiment is a two-system transmission spatial multiplexing system, the first and second pilot signals are inverted in the second transmission system by inverting the pilot signals of even-numbered symbols counted from the first symbol in the OFDM frame. The pilot signal of the transmission system can be an orthogonal code (see FIG. 6).

  Even when the number of transmission systems is 3 or more, the pilot signals can be orthogonally encoded by the same code inversion. As a specific example, Patent Document 1 can be referred to, for example.

  After orthogonal coding of the pilot signal, inverse fast Fourier transform (IFFT; 23a, 23b), addition of guard interval (GI) (24a, 24b), orthogonal modulation (25a, 25b), band pass filtering (BPF; 26a, 26b) and the like, and finally an analog IF signal that can be spatially multiplexed for each system is output by digital-analog conversion (D / A; 27a, 27b) by simultaneous sampling. In other words, the series of signal processing functions as a remodulation unit 37 that remodulates the OFDM frame subjected to code conversion.

  Thereafter, the IF signal output from the spatial multiplexing transmission adapter 13 is input to the reception RF unit 6.

  Next, the internal processing of the spatial multiplexing transmission reception adapter 14 will be described with reference to the block diagram of FIG. Although not shown in the figure, symbol synchronization and frequency synchronization are established in each receiving system.

  First, analog-to-digital conversion (A / D; 15a, 15b), quadrature demodulation (16a, 16b), low frequency by simultaneous sampling, respectively, into two systems of IF signals input from the reception RF unit (9a, 9b) Pass filtering (LPF; 17a, 17b), guard interval (GI) removal (18a, 18b), and fast Fourier transform (FTT; 19a, 19b) are sequentially performed. By these signal processing, the OFDM frame is restored from the analog IF signal. That is, the spatial multiplexing transmission reception adapter 14 also has a configuration that can be said to be a demodulator 38 that restores an OFDM frame from an IF signal.

  Next, the propagation channel estimation unit 28 extracts a pilot signal from the output of the fast Fourier transform (FFT; 19a, 19b), and estimates the propagation channel for each transmission stream. At this time, a pilot signal orthogonally encoded by the spatial multiplexing transmission adapter 13 is used for estimating the propagation channel.

  The MIMO signal separation / detection unit 29 estimates a propagation channel matrix based on the result of the propagation channel estimation unit 28, and uses a normal signal separation algorithm such as Zero Forcing or MMSE (Minimum Mean Square Error), to obtain a spatial space. Separate signals multiplexed in region.

  Next, the CP code inversion unit 30 inverts the sign of the pilot signal in the signal separated by the MIMO signal separation / detection unit 29 again. That is, the sign of the pilot signal that has been inverted so as to be an orthogonal code on the transmission side is inverted again and restored.

  Then, digital signal processing such as inverse fast Fourier transform (IFFT; 23a, 23b), addition of guard interval (GI) (24a, 24b), quadrature modulation (25a, 25b), bandpass filtering (BPF; 26a, 26b) Finally, analog IF signals spatially separated for each system are output by digital-analog conversion (D / A; 27a, 27b) by simultaneous sampling. That is, the spatial multiplexing transmission reception adapter 14 also has a configuration called a remodulation unit 39 that remodulates the OFDM frame.

  The IF signal output from the spatial multiplexing transmission reception adapter 14 is input to the reception control units (10a, 10b).

  According to the above configuration, a transmission adapter and a reception adapter that can realize spatial multiplexing transmission only by adding to an existing apparatus are provided. As can be seen from the above description, the transmission adapter and the reception adapter of this embodiment can be used without modifying the existing device, so that the spatial multiplexing transmission method and the non-spatial multiplexing transmission method are selectively performed. can do.

Although the above embodiment has been described using the configuration of two transmission systems and two reception systems, the present invention can be implemented without any restrictions on the number of systems as long as the number of reception systems is equal to or greater than the number of transmission systems.
[Example 2]

  As different embodiments of the present invention, a description will be given of a transmission adapter for spatial multiplexing and a reception adapter for spatial multiplexing for performing spatial interleaving. Although only the transmission adapter and the reception adapter will be described below, the transmission adapter and the reception adapter according to the present embodiment are used in combination with an existing wireless transmission apparatus as in the first embodiment.

  FIG. 7 is a block diagram illustrating internal processing of the spatial multiplexing transmission adapter according to the present embodiment.

  As can be seen from FIG. 7, in the transmission adapter 13 for spatial multiplexing transmission between the present embodiment and the first embodiment, the carrier exchange units (31a, 31b) are provided between the symbol buffer units (21a, 21b) and the CP code inversion unit 22. ) Is different only in that it is inserted. Therefore, in the description of the present embodiment, signal processing in the carrier exchange units (31a, 31b) will be described, and signal processing in other parts will be omitted.

  The carrier exchange unit (31a, 31b) exchanges the carrier in the same symbol on the time axis between the transmission systems for the OFDM frame output from the symbol buffer unit (21a, 21b). At this time, it is possible to select a carrier to be replaced in advance, and to transmit the information on the carrier to be replaced to the receiver side using a TMCC signal, etc. It is.

  As a carrier exchange system, as shown in FIG. 9, it is conceivable to exchange some carriers over all symbols. That is, a certain carrier is always exchanged between systems in the time direction.

  Alternatively, as a carrier exchange method, as shown in FIG. 10, it is also conceivable to exchange all carriers except the CP carrier in symbol units. In other words, this is a system in which all data carriers are exchanged between systems at a certain timing.

  FIG. 8 is a block diagram illustrating the internal processing of the spatial multiplexing transmission receiving adapter according to this embodiment.

  As can be seen from FIG. 8, in the spatial multiplexing transmission receiving adapter 14 of the present embodiment and the first embodiment, a carrier exchange unit (32a, 32b) is provided between the MIMO signal separation / detection unit 29 and the CP code inversion unit 30. It differs only in that is inserted. Therefore, only the carrier exchange units (32a, 32b) will be described here.

  The carrier exchange unit (32a, 32b) returns the carrier exchanged by the carrier exchange unit (31a, 31b) on the transmission side to the original transmission stream system for the OFDM frame separated by the MIMO signal separation / detection unit 29. Replace. At this time, a method of acquiring the information of the carrier to be replaced from the TMCC signal or a method of fixing in advance between the transmission side and the reception side is possible.

  According to the above configuration, a transmission adapter and a reception adapter that can realize spatial multiplexing transmission only by adding to an existing apparatus are provided. Further, as can be seen from the above description, since the existing apparatus can be used without modification, the spatial multiplexing transmission system and the non-spatial multiplexing transmission system can be selectively realized.

Furthermore, according to the said structure, in addition to the effect of the time interleaving and the frequency interleaving which are the functions of the transmission control part and reception control part which are existing facilities, the effect of a spatial interleaving can be acquired. That is, the error correction function included in the existing equipment is improved, and more stable communication than the conventional one is realized.
[Example 3]

  FIG. 11 is a diagram for explaining an embodiment in which the transmission adapter for spatial multiplexing transmission and the reception adapter for spatial multiplexing transmission according to the present invention are combined with an existing radio transmission apparatus.

  The transmission adapter for spatial multiplexing transmission and the reception adapter for spatial multiplexing transmission used in the present embodiment may be the mode described in the first embodiment or the mode described in the second embodiment. Here, the description will focus on the combination with an existing wireless transmission device.

  As shown in FIG. 11, the spatial multiplexing transmission system of the present embodiment is configured so that the four receiving antennas (8a, 8b, 8c, 8d) are transmitted from the transmitting device 1 having four transmitting antennas (7a, 7b, 7c, 7d). ) To the receiving device 2 having different signal (S1, S2, S3, S4) via the same frequency channel Ch1.

  The transmission device 1 of this embodiment includes a camera 3, an encoder 4, a TS distributor 33, a transmission control unit (5a, 5b, 5c, 5d), a spatial multiplexing transmission adapter 13, a transmission RF unit 6, and a transmission antenna (7a). , 7b, 7c, 7d).

  The camera 3 captures the subject and acquires video information, and the encoder (ENC) 4 encodes the acquired video information and outputs a TS signal in the TS format. The TS distributor lowers the input TS signal to a predetermined video rate and branches the TS signal. The branched TS signals are respectively input to the transmission control units (5a, 5b, 5c, 5d), and the transmission control units (5a, 5b, 5c, 5d) perform transmission path coding on the input TS signals to generate IF signals. Is output. That is, in the configuration of the present embodiment, four systems of IF signals are output using an existing device.

  The transmission adapter 13 for spatial multiplexing transmission demodulates the input four systems of IF signals to obtain OFDM symbols, performs code inversion so that the pilot signals in these systems become orthogonal codes in each system, and performs code inversion The OFDM frame obtained in this way is re-modulated and four systems of IF signals are output. Details of this processing are the same as those in the first and second embodiments.

  The transmission RF unit 6 frequency-converts the IF signal input from the spatial multiplexing transmission adapter 13 using an up-converter whose timing is controlled by a common local oscillator, performs necessary power amplification, and then transmits the transmission antenna (7a, 7b, 7c, 7d).

  As shown in FIG. 11, the receiving apparatus 2 of this embodiment includes a receiving antenna (8a, 8b, 8c, 8d), a receiving RF unit (9a, 9b, 9c, 9d), and a receiving adapter for spatial multiplexing transmission. 14, a reception control unit (10 a, 10 b, 10 c, 10 d), a TS synthesizer 34, a rate converter 35, a decoder (DEC) 11, and a monitor 12.

  The receiving antennas (8a, 8b, 8c, 8d) receive the RF signals (S1, S2, S3, S4) transmitted after being spatially multiplexed, and the receiving RF units (9a, 9b, 9c, 9d) The RF signal is frequency converted and an IF signal is output.

  The spatial multiplexing transmission reception adapter 14 demodulates the four systems of IF signals input from the reception RF units (9a, 9b, 9c, 9d) to obtain an OFDM frame, and again reverses the sign of the pilot signal therein. The OFDM frame that has been sign-inverted again and returned to the original pilot signal is remodulated, and four types of IF signals are output. Details of this processing are the same as those in the first and second embodiments.

  The reception control units (10a, 10b, 10c, 10d) perform transmission path decoding on the input IF signals and output TS signals.

  The TS synthesizer 34 synthesizes four systems of TS signals and outputs one TS signal, and the rate converter 35 converts the video rate of the synthesized TS signal and restores the TS signal on the transmission side. .

  A decoder (DEC) 11 decodes the restored TS signal, extracts video information, and outputs it to the monitor 12.

  According to the above configuration, a transmission adapter and a reception adapter that can realize spatial multiplexing transmission only by adding to an existing apparatus are provided. Further, as can be understood from the above description, since the existing apparatus can be used without modification, the spatial multiplexing transmission system and the non-spatial multiplexing transmission system can be selectively implemented.

  Furthermore, in the transmission system including the transmission apparatus 1 and the reception apparatus 2 configured as described above, more stable and high-quality communication is realized by diversity by spatial multiplexing.

  INDUSTRIAL APPLICABILITY The present invention is useful for applications in which a plurality of non-spatial multiplexing type radio transmission apparatuses are used and these are spatially multiplexed on the same frequency channel.

1, 1a, 1b Transmitting device 2, 2a, 2b Receiving device 3, 3a, 3b Camera 4, 4a, 4b Encoder (ENC)
5a, 5b, 5c, 5d Transmission control unit 6a, 6b, 6c, 6d Transmission RF unit 7a, 7b, 7c, 7d Transmission antenna 8a, 8b, 8c, 8d Reception antenna 9a, 9b, 9c, 9d Reception RF unit 10a, 10b, 10c, 10d Reception control unit 11a, 11b Decoder (DEC)
12a, 12b Monitor 13 Spatial multiplexing transmission adapter 14 Spatial multiplexing reception adapter 15a, 15b Analog-digital conversion (A / D)
16a, 16b Quadrature demodulation 17a, 17b Low-pass filtering (LPF)
18a, 18b Removal of guard interval 19a, 19b Fast Fourier transform (FFT)
20a, 20b Frame head detection unit 21a, 21b Symbol buffer unit 22 CP code inversion unit 23a, 23b Inverse Fast Fourier Transform (IFFT)
24a, 24b Addition of guard interval 25a, 25b Quadrature modulation 26a, 26b Band pass filtering (BPF)
27a, 27b Digital-analog conversion (D / A)
28 Propagation channel estimation unit 29 MIMO signal separation / detection unit 30 CP code inversion unit 31a, 31b Carrier exchange unit 32a, 32b Carrier exchange unit 33 TS distributor 34 TS synthesizer 35 Rate converter 36 Demodulator 37 Remodulator 38 Demodulation Part 39 Remodulation part

Claims (13)

An adapter that is used in combination with a non-spatial multiplex type radio transmission apparatus, and that adapts the radio transmission apparatus to spatial multiplex transmission. A plurality of IF signals modulated by the OFDM method are transmitted from a transmission control unit of the radio transmission apparatus. An adapter that inputs and outputs IF signals of a plurality of systems modulated by the MIMO-OFDM method,
A demodulator that demodulates an input non- spatial multiplexed IF signal to restore an OFDM frame;
A transmission system synchronization unit for synchronizing the OFDM frames of each system;
A CP code inverting unit for inverting the pilot signals so that the pilot signals of the symbols constituting the OFDM frames of the respective systems have orthogonal codes;
A remodulation unit that remodulates the OFDM frame whose code is inverted by the CP code inverter;
A transmission adapter for spatial multiplexing transmission, comprising:   The transmission adapter for spatial multiplexing transmission according to claim 1, further comprising a carrier exchange unit between the transmission system synchronization unit and the CP code inversion unit. The carrier exchange unit, wherein said is a method of exchanging between the transmit line over all symbols Some carrier of each symbol constituting the OFDM frame, space multiplexing transmission according to claim 2 Outbound adapter. The transmission adapter for spatial multiplexing transmission according to claim 2, wherein the carrier exchange unit is a system for exchanging all carriers other than the pilot signal between transmission systems at a certain symbol timing. The output multiple-system IF signals are input to a transmission RF unit including a multiple-system up-converter that is timing-controlled by a common local oscillator,
5. The space according to claim 1, wherein the transmission RF unit converts the output multiple-system IF signals into RF signals and transmits them on the same frequency channel. 6. Multiplex transmission adapter.   6. The spatial multiplexing transmission according to claim 1, wherein the plurality of input IF signals are IF signals obtained by transmission line decoding of different TS signals. Outbound adapter.   6. The input signal according to claim 1, wherein the plurality of input IF signals are IF signals obtained by performing transmission path decoding after distributing one TS signal. 7. Spatial multiplex transmission adapter. An adapter that is used in combination with a non-spatial multiplex type radio receiver, and that adapts the radio receiver to spatial multiplex transmission. It is modulated by the OFDM system by inputting multiple systems of IF signals modulated by the MIMO-OFDM system. An adapter that outputs a plurality of IF signals to the reception control unit of the wireless reception device ,
A demodulator that demodulates an input spatially multiplexed IF signal to restore an OFDM frame;
A receiving system synchronization unit that synchronizes the OFDM frames of each system;
A signal separation unit that performs signal separation based on orthogonality of pilot signals in the OFDM frame;
A CP code inverting unit for inverting the pilot signal of each symbol constituting the OFDM frame separated by the signal separating unit;
A remodulation unit that remodulates the OFDM frame in which the sign of the pilot signal is inverted by the CP code inversion unit,
The CP code inverting unit performs code inverting so as to restore the original code before code inverting on the transmission side.   The receiving adapter for spatial multiplexing transmission according to claim 8, further comprising a carrier exchange unit between the signal separation unit and the CP code inversion unit.   The reception for spatial multiplexing transmission according to claim 9, wherein the carrier exchange unit is a scheme for exchanging a part of carriers of each symbol constituting the OFDM frame between reception systems over all symbols. adapter. The reception adapter for spatial multiplexing transmission according to claim 9, wherein the carrier exchange unit is a system for exchanging all carriers other than the pilot signal between reception systems at a certain symbol timing.   12. The output of any one of claims 8 to 11, wherein the output IF signals of a plurality of systems are subjected to transmission path decoding independently in each system and converted into independent TS signals, respectively. Receiver adapter for spatial multiplexing transmission.   12. The output of any one of claims 8 to 11, wherein the output IF signals of a plurality of systems are independently subjected to transmission path decoding in each system and then combined into one TS signal. Receiver adapter for spatial multiplexing transmission.

Images