JP2015103930A - Transmitter, receiver, and transmission method of ofdm modulation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitter, a receiver and a transmission method of OFDM system which can deal with a variety of more sophisticated OFDM modulation systems, and can transmit and receive unique control information or additional information of a system designer (manufacturer) or a user.SOLUTION: In a transmitter and a receiver of OFDM modulation system where the TMCC(Transmission and Multiplexing Configuration Control) signal containing a synchronization signal and the control information is arranged at a predetermined position of an OFDM frame, the control information of the TMCC signal is differentiated in the even-numbered frame and the odd-numbered frame. Furthermore, a manufacturer definition area is provided in the TMCC signal.

Description

  The present invention relates to a transmitter, a receiver, and a transmission method using an OFDM (Orthogonal Frequency Division Multiplexing) modulation scheme.

  The OFDM modulation method is multicarrier modulation in which data is carried on a large number of carrier waves (subcarriers). Since these subcarriers are orthogonal to each other, they do not interfere with each other unlike conventional frequency division multiplexing (FDM). There are advantages. The OFDM modulation method can be combined with a powerful error correction code and is strong against multipath failure and co-channel interference, and is therefore widely used in broadband digital communication. Specific applications include digital television broadcasting (Non-Patent Document 1), wireless LAN, fourth-generation mobile phones, and the like.

  In recent years, the frequency shift of a specific radio microphone (A type wireless microphone) has been demanded, and a digital wireless microphone in a new frequency band is also being studied. In the frequency reorganization action plan published by the Ministry of Internal Affairs and Communications, the transition frequency band of the specific radio microphone currently at 770 to 806 MHz is the white space of the terrestrial television broadcasting frequency band and the 1.2 GHz band (1240 to 1260 MHz). (Non-Patent Document 2). As a wireless microphone in this frequency band, use of an OFDM modulation method for modulation of an audio signal has been studied. This modulation method is expected to reduce the delay time due to the transmission / reception of the audio signal and prevent the deterioration of the reception quality due to multipath fading.

  In the following, the present invention and the background art thereof will be described taking application to an OFDM wireless microphone as an example, but the application of the present invention is not limited to a wireless microphone.

  The inventors of the present case have already proposed an OFDM transmission / reception system for a wireless microphone in a prior patent application (Japanese Patent Application No. 2013-095976). FIG. 5 shows a basic configuration of the transmission path encoding unit of this OFDM transmitter.

  As shown in FIG. 5, the OFDM transmitter includes an outer code encoder 51, an energy spreader 52, an inner code encoder 53, a carrier modulator 54, a frequency interleaver 55, and a pilot signal generator. 56, a TMCC signal generation unit 57, an OFDM frame configuration unit 58, an IFFT (Inverse Fast Fourier Transform) unit 59, and a guard interval addition unit 60. Further, the carrier modulation unit 54 includes a bit interleaving unit 541 and a mapping unit 542. Among these configurations, the carrier modulation unit 54 to the guard interval addition unit 60 constitute an OFDM modulation unit. Although not shown in the figure, the modulation signal output from the OFDM modulation unit is then converted to an analog signal by the D / A conversion unit, and further modulated to the transmission frequency by the transmission frequency conversion unit, and the power is amplified. It is obvious in the technical field to transmit from the transmitting antenna.

  Each component will be described. An analog audio signal input from the microphone is converted into a digital audio signal by an A / D conversion unit (not shown) and input to the outer code encoding unit 51. The outer code encoding unit 51 divides the data into blocks having a predetermined block length, and adds a parity bit for each block. An outer code is generated by performing block coding using an RS (Reed-Solomon) code, a BCH code, a difference set cyclic code, or a CRC code, and is output to the energy spreading unit 52. In particular, the delay time can be reduced by using a CRC (Cyclic Redundancy Check) code. However, the encoding process of the outer code encoding unit 51 is a process for a concatenated code obtained by combining a plurality of error correction codes, and if it is not a concatenated code, the outer code encoding unit 51 is omitted. Also good.

  The energy spreading unit 52 randomizes the digital audio signal using a pseudo-random signal or the like so that energy is not concentrated on a specific carrier of OFDM due to deviation of audio information. The energy spreading unit 52 and the outer code encoding unit 51 may perform processing in the reverse order.

  The inner code encoding unit 53 performs inner coding (for example, convolutional coding) on the signal input from the energy spreading unit 52, generates an inner code, and outputs the inner code to the carrier modulation unit 54.

  The carrier modulation unit 54 rearranges the data input in bits in the bit interleaving unit 541 with respect to the signal input from the inner code encoding unit 53 without causing a large time delay. As a bit interleaving method, it is desirable to perform bit rotation within one symbol in order to reduce delay. Thereafter, mapping section 542 performs mapping on the IQ plane according to a predetermined modulation scheme (modulation multilevel number M) for each carrier, generates a carrier modulation signal, and outputs the carrier modulation signal to frequency interleaving section 55.

  The frequency interleaving unit 55 rearranges adjacent data so as to disperse in frequency in order to improve tolerance when a specific carrier wave is disturbed, and sends the rearranged data to the OFDM frame configuration unit 58. Output. For the purpose of improving transmission characteristics at the time of mobile reception, for example, in a flat fading environment where the entire band of the OFDM signal is attenuated simultaneously, the frequency interleaving effect cannot be obtained. It is also possible to insert a time interleave unit (not shown) for distributing data and to perform strong transmission line coding.

  The pilot signal generation unit 56 generates a scattered pilot (SP) signal and / or a continuous pilot (CP) signal that serves as a reference signal of amplitude and phase. Since the amplitude and phase at the time of signal generation of these signals are known, the transmission path characteristics can be estimated on the receiving side.

The scattered pilot (SP) is related to W _k corresponding to the OFDM symbol number n and the carrier number _k with respect to the output bit string W _i of the PRBS (Pseudo-random bit sequence) generation circuit. An attached BPSK (Binary Phase Shift Keying) signal can be used.

Further, the continuous pilot (CP) can be a BPSK signal related to W _k corresponding to the carrier number k. The modulation phase is the same in the symbol direction.

  The TMCC signal generation unit 57 generates a TMCC (Transmission and Multiplexing Configuration Control) signal that performs transmission and multiplexing initialization and control. The TMCC signal can transmit control information (transmission mode) that assists the demodulation and decoding of the receiver. The TMCC signal is output to the OFDM frame configuration unit 58 together with the information data and the SP and CP pilot signals.

  The OFDM frame configuration may be, for example, an OFDM frame with a total number of carriers 46 (number of data carriers 39) and 40 symbols. The TMCC signal is transmitted using a specific carrier, and is inserted into three carriers having carrier numbers 2, 22, and 34, for example. Note that the arrangement of TMCC signals is not limited to this. For example, TMCC signals can be inserted into two carriers and transmitted.

A specific structure of the TMCC signal will be described based on Tables 1 and 2. The TMCC signal is usually transmitted as a DBPSK (Differential Binary Phase Shift Keying) signal. The differential reference B ₀ is defined by W _k corresponding to the carrier number k described above. Table 1 shows the correspondence between W _k and the modulation signal. The TMCC modulation signal takes (+4/3, 0) and (−4/3, 0) signal points with respect to information 0 and 1 after differential encoding.

When the OFDM frame has 60 symbols, the information B ′ ₀ to B ′ ₅₉ after differential encoding is defined as follows with respect to the information B ₀ to B ₅₉ before differential encoding.

Table 2 shows an example of the structure of the TMCC signal. The TMCC signal generally includes a synchronization signal, control information, and parity. The synchronization signals B _{1 to} B ₁₆ may be different between even frames and odd frames. For B _{17 to} B _xx−1 , control information (for example, information such as carrier modulation scheme and error correction coding rate) can be set, and the same control information in all frames (even frames and odd frames) Write. Parity information is set for B _{xx to} B ₅₉ .

  The OFDM frame configuration unit 58 inserts SP and CP pilot signals and TMCC signals into the data signal input from the frequency interleaving unit 55 or the time interleaving unit (not shown), and arranges the OFDM segment. A frame is generated and output to the IFFT unit 59.

  The IFFT unit 59 performs an IFFT (Inverse Fast Fourier Transform) process on the OFDM frame input from the OFDM frame configuration unit 58 to generate an IFFT output signal of an effective symbol period. The generated IFFT output signal is output to the guard interval adding unit 60.

  The guard interval adding unit 60 inserts a guard interval obtained by copying the latter half of the IFFT output signal at the head of the IFFT output signal input from the IFFT unit 59. The guard interval is inserted in order to reduce intersymbol interference when receiving an OFDM signal, and is set so that the delay time of the multipath delay wave does not exceed the guard interval length. Thus, an OFDM modulated signal is output.

  Thereafter, a D / A converter (not shown) converts the input digital signal into an analog signal. A transmission frequency converter (not shown) modulates an analog signal input from the D / A converter to a transmission frequency, amplifies the power, and outputs the modulated signal to the reception side via the transmission antenna. Send.

  FIG. 6 shows a basic configuration of an OFDM receiver already proposed by the present inventors. The OFDM receiver includes a guard interval removing unit 61, at least one FFT (Fast Fourier Transform) unit 62, a pilot signal separating unit 63, a channel characteristic estimating unit 64, a TMCC separating unit 65, and a TMCC signal reproduction. Unit 66, division unit 67, frequency deinterleave unit 68, carrier demodulation unit 69, inner code decoding unit 70, energy despreading unit 71, and outer code decoding unit 72. The carrier demodulation unit 69 includes a demapping unit and a bit deinterleaving unit (not shown). Among these configurations, the circuit configuration from the guard interval removal unit 61 to the carrier demodulation unit 69 constitutes an OFDM demodulation unit.

  In FIG. 6, the received signal is received by one system, but a plurality of systems are provided with a guard interval removing unit 61 and an FFT unit 62, for example, four systems of diversity reception are performed, and further, maximum ratio synthesis is performed. Each received signal may be weighted and synthesized according to the level by the unit. Although not shown in the figure, the received signal received from the antenna is modulated to an intermediate frequency by the reception frequency converter, converted to a digital signal by the A / D converter, and input to the OFDM demodulator. Is obvious in the art.

  The guard interval removal unit 61 removes the guard interval given on the transmission side from the signal digitized after reception, and creates an effective symbol signal.

  The FFT unit 62 performs FFT (Fast Fourier Transform) processing on the received signal (effective symbol signal) from which the guard interval is removed.

  The pilot signal separation unit 63 separates the scattered pilot (SP) signal and / or the continuous pilot (CP) signal from the received signal subjected to the FFT processing based on a predetermined OFDM frame configuration, and transmits the transmission path. It outputs to the characteristic estimation part 64.

  The transmission path characteristic estimation unit 64 performs predetermined processing based on the obtained scattered pilot (SP) signal and / or continuous pilot (CP) signal, and estimates transmission characteristics of the signal transmission path. For example, by extracting a certain SP signal and comparing it with a reference value (known amplitude and phase), the transmission path characteristic of the carrier in which the SP signal exists is calculated, and the calculated transmission path characteristic is expressed in the time direction and the frequency direction. To estimate the channel characteristics of all OFDM carriers.

  The TMCC separation unit 65 separates the TMCC signal from the received signal subjected to the FFT processing based on a predetermined OFDM frame configuration and outputs the TMCC signal to the TMCC signal reproduction unit 66.

  The TMCC signal reproduction unit 66 reproduces the TMCC signal separated by the TMCC separation unit 65 and extracts a synchronization signal, control information, and the like.

  The division unit 67 performs division processing on the received signal (main line received signal) subjected to the FFT processing based on the transmission path characteristic estimation value obtained by the transmission path characteristic estimation unit 64 to correct transmission distortion. Get the signal.

  The frequency deinterleave unit 68 performs frequency deinterleave processing on the signal processed by the division unit 67, and restores the data rearranged in frequency. In addition, when time interleaving is performed on the OFDM transmission apparatus side, it is necessary to insert a time deinterleaving unit (not shown) before the frequency deinterleaving unit 68.

  The carrier demodulating unit 69 demodulates the signal input from the frequency deinterleaving unit 68 for each carrier and outputs the demodulated signal to the inner code decoding unit 70. When demodulating, first, an I signal value and a Q signal value are obtained by a demapping unit (not shown) and demodulated into bit unit data. Further, in the bit deinterleave unit (not shown), the data rearranged in units of bits in the transmission side carrier modulation unit is returned to the original arrangement.

  The inner code decoding unit 70 performs inner code decoding processing on the signal input from the carrier demodulation unit 69. The inner code decoding unit 70 performs error correction decoding processing such as Viterbi decoding.

  The energy despreading unit 71 performs energy despreading and returns to the original signal output for output. Next, the outer code decoding unit 72 performs error correction using the error correction code added on the transmission side. If the error that has occurred in the transmission path is discrete, it is possible to correct the error accurately using an error correction code. In some cases, a CRC code or the like is used as the error detection code, and the error correction is not performed in the outer code decoding unit, but only error detection is performed. On the OFDM transmitter side, when the error correction code is not a concatenated code, the outer code decoding unit 72 may be omitted.

  The digital audio signal can be restored by the above processing. Note that the order of the outer code decoding unit 72 and the energy despreading unit 71 can be switched according to the processing order of the transmission apparatus. Thereafter, concealment processing for substituting an appropriate value for error data that could not be corrected by the inner code decoding unit 70 and / or the outer code decoding unit 72 may be performed.

“NHK Digital TV Technical Textbook” February 20, 2007, first edition, editor: Japan Broadcasting Corporation, Publisher: Japan Broadcasting Publishing Association Excerpt from Ministry of Internal Affairs and Communications Electricity Utilization Homepage "Japan's Electricity Utilization Status" 960-3000MHz, [Search November 20, 2013], Internet <URL: http://www.tele.soumu.go.jp/resource/search/ myuse / use / 960m.pdf>

  Conventional OFDM modulation transmission / reception devices transmit control information related to OFDM transmission from the transmission side to the reception side using TMCC signals. However, since the same control information is transmitted in all frames, the limit of TMCC signals is limited. There is a limit to the amount of information that can be transmitted with the determined number of bits. On the other hand, the OFDM transmission system has become more sophisticated in recent years, and the control information to be transmitted has increased, and there has been a problem that it is becoming difficult to transmit all the control information.

  In addition, when an OFDM modulation transmission / reception device is used in a product for general users such as a wireless microphone, each system designer (manufacturer) or each user has his own control information and additional information. However, there is a problem that the frame configuration is not suitable for such needs.

  Therefore, the object of the present invention made in view of the above problems is compatible with a variety of more advanced OFDM modulation schemes, and transmits unique control information and additional information of the system designer or user. Another object of the present invention is to provide a transmission device, a reception device, and a transmission method of an OFDM modulation scheme that can be performed.

  Means for solving the above problem is to make the control information set in the TMCC signal different between even frames and odd frames.

  That is, in order to solve the above-described problem, a transmission apparatus according to the present invention uses an OFDM modulation scheme in which a TMCC (Transmission and Multiplexing Configuration Control) signal including a synchronization signal, control information, and parity is arranged at a predetermined position in an OFDM frame. The transmission apparatus is characterized in that the control information of the TMCC signal differs between even frames and odd frames.

  The TMCC signal preferably has a manufacturer-defined area.

  The control information included in the TMCC signal is preferably different between even frames and odd frames.

  The control information of the TMCC signal preferably includes any information of a carrier modulation scheme, error correction coding rate, time interleaving, system identification, occupied bandwidth, and information identification.

  Further, the manufacturer-defined area of the TMCC signal has a compression mode indicating a method for compressing the audio signal (non-compressed linear PCM, instantaneous companding, ADPCM, etc.), and confidentiality is maintained for the compressed audio data. Scrambled to indicate the presence / absence of encryption, microphone voice sensitivity switching to indicate the input attenuator value for adjusting the microphone's audio input level, transmission power to indicate the RF transmission power value of the microphone, alarm to indicate a device malfunction of the microphone, microphone In order to avoid the interruption of the audio signal at the time of interference, the remaining battery level indicating the battery, the remaining battery level, and time diversity information indicating the sending cycle and number of times of sending the same information repeatedly with time diversity Is preferably included.

  In order to solve the above problems, a receiving apparatus according to the present invention separates a TMCC (Transmission and Multiplexing Configuration Control) signal from a received signal subjected to FFT (Fast Fourier Transform) processing, and at least a synchronization signal from the separated signal. And a control signal extraction apparatus that extracts different control signals from the TMCC signals of even frames and odd frames.

  Further, it is desirable to extract information set in the manufacturer definition area from the TMCC signal.

  In order to solve the above-described problems, a transmission method according to the present invention includes an OFDM modulation scheme that transmits and receives an OFDM frame in which a transmission and multiplexing configuration control (TMCC) signal including a synchronization signal, control information, and parity is arranged at a predetermined position. The TMCC signal is characterized in that the control information differs between even frames and odd frames.

  According to the present invention, the control information set in the TMCC signal is made different between even frames and odd frames, so that twice as much control information as before can be transmitted, and it corresponds to various more advanced OFDM modulation schemes. can do. In addition, according to the manufacturer definition area set in the TMCC signal, the system designer (manufacturer) or the user's original control information and additional information can be transmitted to the receiver side.

6 is a diagram illustrating an example of a configuration of a TMCC signal according to Embodiment 1. FIG. 6 is a diagram illustrating an example of a manufacturer-defined area of a TMCC signal according to Embodiment 1. FIG. 6 is a diagram illustrating an example of a configuration of a TMCC signal according to Embodiment 2. FIG. 10 is a diagram illustrating an example of a manufacturer-defined region of a TMCC signal according to Embodiment 2. FIG. It is a block diagram which shows the structure of the proposed OFDM transmission apparatus. It is a block diagram which shows the structure of the proposed OFDM receiver.

  Embodiments of the present invention will be described below.

(Embodiment 1)
FIG. 1 is a diagram showing a configuration of a TMCC signal used in the OFDM transmission / reception apparatus according to Embodiment 1 of the present invention. The overall configuration of the OFDM transmitter of the present invention can be basically the same as the proposed transmitter shown in FIG. 5, and the TMCC signal generated by the TMCC signal generator 57 is different from the conventional one.

  The TMCC signal shown in FIG. 1 is different from the conventional one in that control information transmitted in an even frame and an odd frame is different. Therefore, if the number of bits of the TMCC signal is the same, control information twice that of the conventional TMCC signal can be transmitted. In addition, a manufacturer definition area is provided, and information can be freely defined and set by a system designer (manufacturer) or a user. FIG. 1 shows an example in which an OFDM frame is composed of 60 symbols. Therefore, the TMCC signal also makes a round with 60 bits. For example, in the mode in which the occupied bandwidth is 600 kHz, the time for one round is 5.0 ms. In the case of 288 kHz, it becomes 10.833 ms, and in the case of 192 kHz, it becomes 16.25 ms. Note that the number of bits of the TMCC signal is not limited to this, and is appropriately set according to the number of symbols in the OFDM frame. The structure will be specifically described below.

The first bit B ₀ of the TMCC signal is a signal serving as a reference for differential demodulation, as in the conventional, PRBS: to the output bit sequence W _i of (Pseudo-random bit sequence a pseudo-random bit sequence) generator , A signal related to W _k corresponding to the OFDM carrier number k. Other reference signals may be used. Subsequent bit numbers B ₁ to B ₅₉ are differentially encoded according to the above-mentioned definition of (Equation 2).

Bit numbers B ₁ to B ₁₆ are synchronization signals, and a 16-bit signal is set as in the conventional case. For example, the even frame and the odd frame can be complementary bit strings. Note that the synchronization signal is not limited to the number of bits and the bit string shown in FIG.

In the example of FIG. 1, the next B ₁₇ to B ₂₃ are allocated to the control information, and the control information to be transmitted is completely different between the even frame and the odd frame. For example, for even frames, carrier modulation information is set in 2 bits from B ₁₇ to B ₁₈ , information in time interleaving is set in 3 bits from B ₁₉ to B ₂₁ , and 2 bits from B ₂₂ to B ₂₃ are set. Set the occupied bandwidth information. On the other hand, error correction coding rate information is set in 2 bits from B ₁₇ to B ₁₈ for odd frames, system identification information is set in 3 bits from B ₁₉ to B ₂₁ , and B ₂₂ to B Information identification information is set in 2 bits of ₂₃ . Note that the type of information and the setting location are not limited to this.

In the example of FIG. 1, 4 bits from B ₂₄ to B ₂₇ of the TMCC signal are reserved. Further, 20 bits from B ₂₈ to B ₄₇ are used as the manufacturer definition area. The manufacturer definition area is an area where system designers (manufacturers) or users can freely define and set information. Even if the same information is set for even frames and odd frames, different information can be set. Also good.

The 12 bits B ₄₈ to B ₅₉ are used for parity in both even and odd frames. The error correction code can be selected as appropriate. For example, the error correction code may be a BCH shortened code (43, 31) having an error-correctable bit number t = 2.

FIG. 2 is a setting example of the manufacturer definition area arranged from B ₂₈ to B ₄₇ (20 bits) in the TMCC signal of FIG. For compression mode (LPCM [Linear Pulse Code Modulation], IC [Instantaneous Companding], ICS [Instantaneous Companding for stereo], AC [Audio Compression for Stereo]) indicating the method of compressing the audio signal, Scramble indicating the presence / absence of encryption for confidentiality maintenance, sensitivity switching of microphone sound indicating an input attenuator value for adjusting the sound input level of the microphone, transmission power indicating the microphone RF transmission power value, indicating a device abnormality of the microphone Information such as the alarm, the battery of the microphone and the remaining battery level indicating the remaining battery level can be freely set. In the example of FIG. 2, the odd frame is used as a spare area. However, the information is appropriately distributed to the even frame and the odd frame. For important information, the same information is set in both frames, and reliable transmission is performed. It can also be done.

  The overall configuration of the OFDM receiving apparatus of the present invention that receives the TMCC signal of FIG. 1 can be basically the same as the proposed transmitting apparatus shown in FIG. The TMCC signal and subsequent processing are different from conventional ones.

  The TMCC signal reproduction unit 66 separately extracts control information from the TMCC signals obtained in the even and odd frames, and performs carrier demodulation and decoding processing based on the obtained control information. Further, predetermined information is separated and extracted from the manufacturer definition area and used for control or the like in the OFDM receiver.

  As described above, according to the OFDM transmitter, receiver, and transmission method of the first embodiment, a lot of control information can be set in the TMCC signal, and information can be freely set in the manufacturer definition area. It is possible to cope with a more advanced OFDM transmission system.

(Embodiment 2)
The second embodiment of the present invention will be described below. FIG. 3 is a diagram showing a configuration of a TMCC signal used in the OFDM transmission / reception apparatus according to Embodiment 2 of the present invention. Also in the second embodiment, the overall configuration of the OFDM transmitter and receiver can be basically the same as the proposed transmitter / receiver shown in FIGS. 5 and 6, and is generated by the TMCC signal generator 57. The TMCC signal processed by the TMCC signal reproduction unit 66 is different from the conventional one.

  The TMCC signal shown in FIG. 3 is different from the conventional one in that the control information transmitted in the even frame and the odd frame is different. In addition, although the control information of the TMCC signal in FIG. 1 is completely different between even frames and odd frames, the TMCC signal in FIG. 3 has some important control information (for example, information on the carrier modulation scheme) even. Frames and odd frames are set redundantly, and other control information is set only in either the even frame or the odd frame. Therefore, it is possible to reliably transmit important control information and to transmit more control information than the conventional TMCC signal. Further, similarly to the TMCC signal of FIG. 1, it has a manufacturer-defined area. The structure will be specifically described below.

FIG. 3 shows an example in which an OFDM frame is composed of 60 symbols. Therefore, the TMCC signal also makes a round with 60 bits. The first bit B ₀ of the TMCC signal is a signal used as a reference for differential demodulation, and is related to W _k corresponding to the OFDM carrier number _k with respect to the output bit string W _i of the PRBS generation circuit, as in the past. Signal. Subsequent bit numbers B ₁ to B ₅₉ are differentially encoded according to the above-mentioned definition of (Equation 2).

Bit numbers B ₁ to B ₁₆ are synchronization signals, and a 16-bit signal is set as in the conventional case. For example, the even frame and the odd frame can be complementary bit strings. Note that the synchronization signal is not limited to the number of bits and the bit string shown in FIG.

In the example of FIG. 3, the next area from B ₁₇ to B ₃₀ is assigned to the control information, and even frames and odd frames have the same control information (for example, information on the carrier modulation scheme) in B ₁₇ to B _20. ) Is set, and different control information is set in other areas. That is, for even frames, information on the carrier modulation scheme is set in 2 bits from B ₁₇ to B ₁₈ , information on the error correction coding rate is set in 2 bits from B ₁₉ to B ₂₀ , and B ₂₁ to B ₂₃ are set. Time interleave information is set in 3 bits, occupied bandwidth information is set in 2 bits from B ₂₄ to B ₂₅ , information identification information is set in 2 bits from B ₂₆ to B ₂₇ , and B ₂₈ to B ₃₀ 3 bits are reserved. On the other hand, in the odd frame, the same carrier modulation information as the even frame is set in 2 bits from B ₁₇ to B ₁₈ and the error correction coding rate information is set in 2 bits from B ₁₉ to B _20. , B ₂₁ to B ₂₇ are reserved, and system identification information is set to 3 bits B ₂₈ to B ₃₀ .

In the example of FIG. 3, and the _{B 31} of the TMCC signals of 17 bits of _{B 47} and manufacturer definition area. The manufacturer definition area is an area where system designers (manufacturers) or users can freely define and set information. Even if the same information is set for even frames and odd frames, different information can be set. Also good.

The 12 bits B ₄₈ to B ₅₉ are used for parity in both even and odd frames. The error correction code can be selected as appropriate. For example, the error correction code may be a BCH shortened code (43, 31) having an error-correctable bit number t = 2.

FIG. 4 is an example of setting the manufacturer definition area arranged from B ₃₀ to B ₄₇ (17 bits) in the TMCC signal of FIG. In this example, information such as audio signal compression mode, scramble, microphone audio sensitivity switching, transmission power, alarm, battery level, etc. is set for even frames, and the time diversity sending period and time diversity sending count are set for odd frames. Information is set. Note that the time diversity transmission method and the transmission period described above are time diversity transmission methods in which a symbol including the same audio signal is repeatedly transmitted a plurality of times in order to avoid interruption of the audio signal at the time of interference in the OFDM modulation scheme. Is information corresponding to. The manufacturer-defined information can be appropriately distributed between even frames and odd frames, or the same information can be set in both frames as necessary, and reliable transmission can be performed.

  As described above, according to the OFDM transmitter, the receiver, and the transmission method according to Embodiment 2, it is possible to set a large amount of control information in the TMCC signal and reliably transmit important control information. In addition, information can be freely set in the manufacturer definition area, and it is possible to cope with a more advanced OFDM transmission system.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, the functions and the like included in each means can be rearranged so as not to be logically contradictory, and a plurality of means and the like can be combined into one or divided.

51 Outer Code Encoding Unit 52 Energy Spreading Unit 53 Inner Code Encoding Unit 54 Carrier Modulating Unit 55 Frequency Interleaving Unit 56 Pilot Signal Generation Unit 57 TMCC Signal Generation Unit 58 OFDM Frame Configuration Unit 59 IFFT Unit 60 Guard Interval Addition Unit 61 Guard Interval Removal unit 62 FFT unit 63 Pilot signal separation unit 64 Transmission path characteristic estimation unit 65 TMCC separation unit 66 TMCC signal regeneration unit 67 Division unit 68 Frequency deinterleaving unit 69 Carrier demodulation unit 70 Inner code decoding unit 71 Energy despreading unit 72 Outer code Decryption unit

Claims (8)

  A transmission apparatus of an OFDM modulation scheme that arranges a transmission and multiplexing configuration control (TMCC) signal including a synchronization signal, control information, and parity at a predetermined position of an OFDM frame, wherein the control information of the TMCC signal is an even frame. And an odd number of frames.   2. The transmission apparatus according to claim 1, wherein the TMCC signal has a manufacturer-defined area.   2. The transmission apparatus according to claim 1, wherein the control information included in the TMCC signal is different between even frames and odd frames.   2. The transmission apparatus according to claim 1, wherein the control information of the TMCC signal includes any information of a carrier modulation scheme, an error correction coding rate, time interleaving, system identification, occupied bandwidth, and information identification. A transmitter characterized by the above.   3. The transmission device according to claim 2, wherein the manufacturer-defined area of the TMCC signal includes any information of compression mode, scramble, microphone sound sensitivity switching, transmission power, alarm, remaining battery level, and time diversity. A transmission apparatus characterized by the above.   An OFDM modulation type receiving apparatus that separates a transmission and multiplexing configuration control (TMCC) signal from a received signal that has been subjected to FFT (Fast Fourier Transform) processing, and extracts at least a synchronization signal and a control signal from the separated signal. Thus, different control signals are extracted from the TMCC signals of even frames and odd frames, respectively.   The receiving apparatus according to claim 6, wherein information set in a manufacturer-defined area is extracted from the TMCC signal. A transmission method of an OFDM modulation scheme that transmits and receives an OFDM frame in which a TMCC (Transmission and Multiplexing Configuration Control) signal including a synchronization signal, control information, and parity is arranged at a predetermined position, wherein the TMCC signal includes an even frame, The transmission method characterized in that the control information is different for odd frames.

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