JP6195755B2 - OFDM modulation system transmitter and receiver - Google Patents

Description

The present invention, OFDM (Orthogonal Frequency Division Multiplexing: orthogonal frequency division multiplexing) relates to a transmitting apparatus and receiving apparatus according to a 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 energy spreading unit 51, an outer code encoding unit 52, an inner code encoding unit 53, a carrier modulation unit 54, a frequency interleaving unit 55, and a pilot signal generating unit. 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 converter (not shown) and input to the energy diffusing unit 51. The energy spreading unit 51 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 the deviation of the audio information.

  The outer code encoding unit 52 divides the data into blocks having a predetermined block length, and adds a parity bit for each block. Block coding is performed by RS (Reed-Solomon) code, BCH code, difference set cyclic code, or CRC code to generate an outer code, which is output to the inner code coding unit 53. This is because error correction is performed on the receiving side, or error detection is performed and concealment is performed on an erroneous block. In particular, the delay time can be reduced by using a CRC (Cyclic Redundancy Check) code. The energy spreading unit 51 and the outer code encoding unit 52 may perform processing in the reverse order.

  The inner code encoder 53 performs inner encoding (for example, convolutional encoding) on the signal input from the outer code encoder 52, generates an inner code, and outputs the inner code to the carrier modulator 54.

  The carrier modulation unit 54 rearranges the data input in bits in the bit interleaving unit 541 for 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 to 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 be dispersed in frequency in order to improve tolerance when a specific carrier wave is disturbed, and the rearranged data is sent to the OFDM frame configuration unit 58. Output.

  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.

Scattered Pilot (SP) is, PRBS: to the output bit sequence _{W i} of (Pseudo-random bit sequence a pseudo-random bit sequence) generator, related to _{W i} corresponding to the symbol number n and the carrier number k of OFDM It can be an attached BPSK signal. The correspondence W _i and the modulation signal shown in Table 1.

Further, the continuous pilot (CP) can be a BPSK signal related to W _k corresponding to the carrier number k. Table 1 shows the correspondence between W _k and the modulation signal. 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 demodulation and decoding of the receiver, battery remaining amount information, and the like. 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 unit 58 generates an OFDM segment frame by inserting and arranging the SP and CP pilot signals and the TMCC signal with respect to the data signal input from the frequency interleaving unit 55 and outputs the OFDM segment frame to the IFFT unit 18. To do.

  FIG. 7 shows an OFDM frame configuration already proposed by the present inventors, and is an example of an OFDM frame using QPSK and 16QAM modulation and having a total number of carriers 46 (number of data carriers 39). Dn, k represents a carrier symbol of data after interleaving. Here, “k” corresponds to the number in the carrier direction in the OFDM frame configuration, and “n” corresponds to the number in the symbol direction. Scattered pilot (SP) signals arranged in a distributed manner are inserted, for example, once every 15 carriers in the carrier direction and once every 5 symbols in the symbol direction as shown in FIG. Also, a continuous pilot (CP) signal arranged continuously in the symbol direction may be inserted. Also, the TMCC signal (T), which is a signal for transmitting control information, is transmitted using a specific carrier and can be inserted into, for example, three carriers of carrier numbers 2, 20, and 34. Note that the configuration of the OFDM frame is not limited to this, and for example, a TMCC signal can be inserted into two carriers and transmitted.

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

  The guard interval adding unit inserts a guard interval obtained by copying the latter half of the effective symbol signal at the head of the effective symbol 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 the basic configuration of an OFDM receiver already proposed by the present inventors. The OFDM receiver includes a guard interval removal unit 61, at least one FFT (Fast Fourier Transform) unit 62, a scattered pilot (SP) separation unit 63, a continuous pilot (CP) separation unit 64, and a TMCC. Separator 65, Wi multiplier 66, transmission path characteristic estimator 67, TMCC signal regenerator 68, divider 69, frequency deinterleaver 70, carrier demodulator 71, inner code decoder 72, The outer code decoding unit 73 and the energy despreading unit 74 are provided. The carrier demodulation unit 71 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 71 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.

  A scattered pilot (SP) separation unit 63, a continuous pilot (CP) separation unit 64, and a TMCC separation unit 65 are each configured to scan a received signal subjected to FFT processing based on a predetermined OFDM frame configuration. Separates the Cuttered Pilot (SP) signal, the Continuous Pilot (CP) signal, and the TMCC signal.

W _i multiplier unit 66, the bit sequence W _i same bit sequence W _i used in the transmission side generates in PRBS generation circuit, the multiplication process for separated scattered pilot (SP) signal. For Continuous al pilot (CP) signal, multiplication by the bit sequence W _i is unnecessary. Thereby, the reference signal of the pilot signal that has passed through the transmission path is obtained.

Channel estimation unit 67, based on W _i multiplication section obtained scattered pilot from 66 (SP) signal and / or continuous Al pilot (CP) signal, estimates the transmission characteristic 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 signal reproduction unit 68 reproduces the TMCC signal separated by the TMCC separation unit, and extracts a synchronization signal, a control signal, and the like.

  The division unit 69 performs division processing on the received signal (main line received signal) subjected to FFT processing based on the transmission path characteristic estimation value obtained by the transmission path characteristic estimation unit 67 to correct transmission distortion. Get the signal.

  The frequency deinterleave unit 70 performs frequency deinterleave processing on the signal processed by the divider 69, and restores the data rearranged in frequency.

  The carrier demodulating unit 71 demodulates the signal input from the frequency deinterleaving unit 70 for each carrier and outputs the demodulated signal to the inner code decoding unit 72. 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. Also, in the bit deinterleave unit (not shown), the data rearranged in units of bits in the carrier modulation unit on the transmission side is returned to the original arrangement.

  The inner code decoding unit 72 performs an inner code decoding process on the signal input from the carrier demodulation unit 71. The inner code decoding unit 72 performs error correction decoding processing such as Viterbi decoding.

  The outer code decoding unit 73 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.

  Next, the energy despreading unit 74 performs energy despreading to return to the original signal output and output it. The digital audio signal can be restored by the above processing. Note that the order of the outer code decoding unit 73 and the energy despreading unit 74 can be switched in accordance with 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 72 and / or the outer code decoding unit 73 can 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 June 12, 2013], Internet <URL: http://www.tele.soumu.go.jp/resource/search/ myuse / use / 960m.pdf>

Previously transmitting receiving device of the OFDM scheme (e.g., wireless microphone) is code W _i is already initialized to be multiplied to the pilot signal on the transmission side, since it is identical between different apparatus, the same space Thus, if a plurality of transmission / reception devices are used at the same frequency, there is a problem that interference is generated in the received pilot signal and the estimation accuracy of the transmission path characteristics is lowered.

  As a result of the degradation of the estimation accuracy of the transmission path characteristics, there is no noise margin, and when using the transmitter / receiver (wireless microphone) at the same frequency in the same space, the separation distance for operation is large. Thus, there is a problem that the number of devices (number of microphones) that can be used simultaneously in the same space is reduced.

Therefore, an object of the present invention made in view of the above problems is to receive a pilot signal even when a plurality of sets of OFDM modulation transmission / reception apparatuses are used at the same frequency in the same space. An object of the present invention is to provide a transmitter and a receiver that do not cause interference.

Transmitting receiving device according to the present invention in order to solve the above problems, a function of setting a group number, the code W _i to be multiplied to the pilot signal, according to the group numbers set, different initial values Is assigned to the PRBS generation circuit, and the code _Wi is made different for each group.

That is, in order to solve the above problem, a transmission apparatus according to the present invention uses an output bit string Wi of a PRBS generation circuit as at least one of a scattered pilot (SP) reference signal, a continuous pilot (CP) reference signal, and a TMCC signal. In an OFDM modulation transmission device that multiplies two signals and places the multiplied signal at a predetermined position in the OFDM frame, a group number setting unit that can set a desired group number, and a set group number And an initial value generator for generating an initial value of the PRBS generation circuit, the output bit string Wi of the PRBS generation circuit is made different for each group number, and the synchronization signal of the TMCC signal is set for each group number. Set different sync signal patterns according to the group number setting, and It is then characterized in that it does not multiply the output bit sequence Wi.

In order to solve the above problem, a transmission apparatus according to the present invention uses an output bit string Wi of a PRBS generation circuit as at least one of a scattered pilot (SP) reference signal, a continuous pilot (CP) reference signal, and a TMCC signal. In an OFDM modulation transmission device that multiplies two signals and places the multiplied signal at a predetermined position in the OFDM frame, a group number setting unit that can set a desired group number, and a set group number And an initial value generation unit for generating an initial value of the PRBS generation circuit, the output bit string Wi of the PRBS generation circuit is made different for each group number, and the synchronization signal of the TMCC signal is between the group numbers. The basic pattern signal is multiplied by the output bit string Wi. And, and generating a different synchronization signals for each group number.

In order to solve the above-described problem, a receiving apparatus according to the present invention is configured to receive at least one of a scattered pilot (SP) signal, a continuous pilot (CP) signal, and a TMCC signal from a received signal that has been subjected to FFT (Fast Fourier Transform) processing. An OFDM modulation method for separating one signal, multiplying the separated signal by an output bit string Wi of a PRBS generation circuit, and estimating transmission path characteristics or extracting a synchronization signal and a control signal based on the multiplied signal In the receiving apparatus, a group number setting unit capable of setting a desired group number and an initial value generating unit for generating an initial value of the PRBS generation circuit corresponding to the set group number are provided, and the PRBS generation The output bit string Wi of the circuit is made different for each group number, and the synchronization signal of the TMCC signal included in the received signal is: A different sync signal pattern for each group number is set according to the setting of the group number, the sync signal is not multiplied by the output bit string Wi, and a different sync signal for each group number It is characterized in that synchronization is taken on the basis of the pattern .

In order to solve the above-described problem, a receiving apparatus according to the present invention is configured to receive at least one of a scattered pilot (SP) signal, a continuous pilot (CP) signal, and a TMCC signal from a received signal that has been subjected to FFT (Fast Fourier Transform) processing. An OFDM modulation method for separating one signal, multiplying the separated signal by an output bit string Wi of a PRBS generation circuit, and estimating transmission path characteristics or extracting a synchronization signal and a control signal based on the multiplied signal In the receiving apparatus, a group number setting unit capable of setting a desired group number and an initial value generating unit for generating an initial value of the PRBS generation circuit corresponding to the set group number are provided, and the PRBS generation The output bit string Wi of the circuit is made different for each group number, and the synchronization signal of the TMCC signal included in the received signal is: A basic pattern signal common to the group numbers is multiplied by the output bit string Wi to generate a different synchronization signal for each group number, and synchronization is performed based on a synchronization signal different for each group number. It is characterized by taking .

  According to the present invention, pilot signals set with different group numbers do not interfere with each other, and the problem that the accuracy of the received pilot signal, and hence the estimation accuracy of the transmission path characteristics, can be solved. When using multiple transmitter / receiver devices (for example, wireless microphones) at the same frequency, reduce the separation distance for operation and increase the number of devices (number of microphones) that can be used simultaneously in the same space. be able to.

1 is a block diagram showing a configuration of an OFDM transmission apparatus according to Embodiment 1. FIG. 3 is an example of a PRBS generation circuit and initial values according to the first embodiment. 6 is a diagram illustrating a correspondence between an OFDM frame configuration and a signal Wi according to Embodiment 1. FIG. 6 is a block diagram showing a configuration of an OFDM receiving apparatus 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. It is a figure which shows the proposed OFDM frame structure.

  Embodiments of the present invention will be described below.

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of an OFDM transmission apparatus according to Embodiment 1 of the present invention. The overall configuration of the OFDM transmitter of the present invention is the same as that of the proposed transmitter shown in FIG. 5, and the same configuration is omitted. The present invention is different from the transmission apparatus shown in FIG. In the present specification, hereinafter, the scattered pilot (SP) signal and the continuous pilot (CP) signal, including the TMCC signal, may be referred to as a pilot signal.

1, the transmitting side, showing a configuration for changing the initial value of W _i according to the group number set. The OFDM frame configuration unit 11 in FIG. 1 is equivalent to the OFDM frame configuration unit 58 in FIG. 1 includes a scattered pilot (SP) generation unit 12, a continuous pilot (CP) generation unit 13, and a TMCC generation unit 14, a group number setting unit 15, an initial value generation unit 16, A _Wi multiplier 17 for each pilot signal is provided.

The scattered pilot (SP) generation unit 12 and the continuous pilot (CP) generation unit 13 have a predetermined pattern and reference signals of the SP and CP pilot signals (for example, signals based on the data “1”). Is generated. That is, thereafter, each pilot signal to be inserted into the OFDM frame is generated by performing _Wi multiplication processing described later. In addition, the TMCC generation unit 14 generates a TMCC signal according to a TMCC generation procedure described later.

  The group number setting unit 15 outputs a set arbitrary group number based on a user setting or the like. In the present specification, groups are distinguished by numbers, but this number does not necessarily mean numbers, but means that a code that can be distinguished by some group is assigned.

Based on the group number set by the group number setting unit 15, the initial value generation unit 16 generates an initial value to be given to, for example, the PRBS generation circuit shown in FIG. The relationship between the group number and the initial value (the first value to produce a W _0), for example, associating as in FIG. 2 (b).

W _i multiplier 17, based on the initial value corresponding to the group number set to generate a PRBS bit sequence _{W i,} multiplied by the generated _{W i} SP, CP, at least one of the respective pilot signals of the TMCC By doing so, code spreading of the pilot signal is performed. Incidentally, when the multiplication process, case of multiplying the SP only _{W i,} case of multiplying the SP and CP only _{W i,} SP, CP, case or the like is conceivable multiplying _{W i} for all TMCC. Here, for example, CP pilot signal by providing an offset to the CP pilot signal and the carrier numbers of the OFDM signal of another transmission apparatus, it is possible to prevent interference, necessarily W _i if such There is no need to multiply. Further, TMCC signal, for easier synchronization, may not be multiplied by _{W i.} Thus, either multiplies W _i to which the pilot signals can be performed as needed.

  The OFDM frame configuration unit 11 receives the carrier-modulated digital audio signal from the frequency interleaving unit and synthesizes the pilot signal and the digital signal to create an OFDM segment frame, as described with reference to FIG. Then, the data is output to the IFFT unit 59.

Then, by multiplying the W _i, supplement the code spreading the pilot signal. The PRBS generator polynomial is expressed by the following equation, for example.

^{g (x) = X 11 +} X 9 + 1 (1) formula

This PRBS generation polynomial is realized by the PRBS generation circuit shown in FIG. In the circuit of FIG. 2A, 11 stages of bit delay circuits 21 are connected in series so as to constitute a shift register, the outputs of the 9th and 11th stages are input to the EX-OR 22, and the result is obtained. Input in the first stage. This as the output 23 of the PRBS generator, the output bit sequence _{W i} corresponding to the OFDM symbol number n and the carrier number k is obtained. The PRBS generation circuit and the initial value are not limited to those shown in FIG.

_Wi is reset to W ₀ every OFDM frame (for example, 40 symbols). The initial value of FIG. 2B is given as the initial value of PWBS applied to W ₀ when reset (that is, the initial value given first to each stage of the shift register of the PRBS generation circuit). For example, if the group number is 1, each bit of the initial value “11111111111” is given as the value of each stage (1) to (11) of the shift register 21.

Here, PN (Pseudorandom Noise: pseudo-noise) code, the code length for the number l of the shift register becomes ² l ^{-1, 2} l -1 pieces of _{W i} is generated cyclically. Changing the initial value corresponds to changing the phase of the code length 2 ^l −1.

Code adopted as the initial value of W ₀ "distance codes W ₀ between different group numbers, it. Does not match an integer multiple of the total number of subcarriers of OFDM" must satisfy the condition that. Here, the code distance refers to the number of codes output from the PWBS generation circuit. If it matches an integer multiple of the total number of subcarriers, even if a different group number is set, a condition (same W _{i for the} same subcarrier) that matches other transmitters with different phases of the pilot signal in time. May occur). If they match, the transmission path characteristic estimation is adversely affected.

As an example, if the total number of OFDM subcarriers is 46, using an integral multiple of this, for example, 5 times that SP makes a round with 5 symbols, a distance of 46 × 5 = 230 can identify a group. It is the distance that disappears. Here, in view of these, as an example, the initial value was obtained by setting 231 including 1 as the distance between codes between groups. FIG. 2B is an example of the initial value obtained in this way. By adding 1, the codes do not match in the two-dimensional space of _Wnk across groups, and interference from wireless microphones having different group numbers and assigned different initial values can be randomized. . Thereby, the error correction capability with respect to the error correction interference of the received wireless microphone signal can be enhanced.

Based on the OFDM symbol number n and carrier number k, the shift register output signal W _i is assigned to the OFDM frame structure as W _nk sequentially from the carrier direction as shown in FIG. After allocating to the rightmost carrier, one is updated in the symbol direction and sequentially allocated in the carrier direction. That is, W _i is allocated based on W _nk in which the SP pilot signal is arranged, and the allocated W _i is multiplied by the SP reference signal. For example, in FIG. 7, for the SP pilot signal of symbol number 1 and carrier number 3, the 49th W _i (ie, W _1,3 = W ₄₉ ) corresponding to FIG. Is multiplied.

Next, the setting of the TMCC signal will be described. The TMCC signal is transmitted as a DBPSK signal. Differential reference B0 is defined by _{W i} described above. The TMCC modulation signal takes (+4/3, 0) and (−4/3, 0) signal points with respect to information 0 and 1 after differential encoding.

  Information B′0 to B′39 after differential encoding is defined as follows with respect to information B0 to B39 before differential encoding.

Regarding the reference for differential demodulation of B0 and the synchronization signals of B1 to B16, different synchronization signals may be created in advance for each group number as shown in Table 3 and assigned. In this case, for B1~B16 synchronization signals of the TMCC signal, it does not perform multiplication processing of _{W i.} This is because it may be difficult to achieve synchronization by performing multiplication processing on the synchronization signal. As another method of creating the synchronization signal, the basic pattern of the synchronizing signal (B1 to B16) in common with each transmitting receiving device multiplies different W _i for each group (code spread), it can be distinguished from each other A synchronization signal may be generated. Thereby, a different synchronization signal for each group can be obtained. About B17-B39, the value similar to the past shown by Formula 3 and Table 2 can be set.

Then, if necessary, for B17～B39, it is possible to perform multiplication processing of _{W i.}

According to the OFDM transmitting apparatus of the present invention, each group number, different can be set PRBS output bit sequence W _i, it is possible to facilitate the identification of the pilot signal on the receiving side.

(Embodiment 2)
A receiving apparatus will be described below as Embodiment 2 of the present invention. FIG. 4 is a block diagram showing a configuration of an OFDM receiving apparatus according to Embodiment 2 of the present invention. The overall configuration of the OFDM receiving apparatus of the present invention is the same as the proposed transmitting apparatus shown in FIG. 6, and the same configuration is omitted. The present invention differs from the receiving apparatus of FIG. 6 in that the transmission path characteristics and the synchronization signal are derived after separating the pilot signal.

Figure 4 shows an arrangement for changing the initial value of W _i according to the group number set on the receiving side. 4 includes at least one FFT (Fast Fourier Transform) unit 41, a scattered pilot (SP) separation unit 42, a continuous pilot (CP) separation unit 43, and a TMCC separation unit 44. In addition, a group number setting unit 45, an initial value generation unit 46, and a _Wi multiplication unit 47 for each pilot signal are provided. The transmission path characteristic estimation unit 48, the TMCC signal reproduction unit 50, and the division unit 49 have basically the same functions as those shown in FIG.

  The scattered pilot (SP) separation unit 42, the continuous pilot (CP) separation unit 43, and the TMCC separation unit 44 separate the SP, CP, and TMCC pilot signals, respectively, based on the OFDM frame configuration.

  The group number setting unit 45 outputs a set arbitrary group number based on a user setting or the like.

Based on the group number set by the group number setting unit 45, the initial value generation unit 46 generates, for example, an initial value to be given to the PRBS generation circuit shown in FIG. Relationship group number and the initial value (the first value to produce a W _0), for example, be configured with the same correspondence between the transmission side as shown in FIG. 2 (b). _Wi is reset to W ₀ every OFDM frame (for example, 40 symbols). As the initial value of PWBS applied to _{W 0} at the time of reset, giving the initial value of the FIG. 2 (b). For example, if the group number is 1, each bit of the initial value “11111111111” is given as the value of each stage (1) to (11) of the shift register 21.

W _i multiplier unit 47, based on the initial value corresponding to the group number set to generate a PRBS bit sequence W _i Like the transmission side, SP for the generated W _i, separated from the received signal, CP, Multiply each pilot signal of TMCC. Incidentally, when the multiplication process, case of multiplying the SP only _{W i,} case of multiplying the SP and CP only _{W i,} SP, CP, case or the like is considered to multiply _{W i} for all TMCC, line on the transmission side It is desirable to perform the multiplication process on the receiving side corresponding to the multiplication process.

If the transmission side and the group are different, the bit string _Wi is generated from a pseudo-random (PN) code. Therefore, the interference signal set with a code having a different initial value is diffused as a result of multiplication. It becomes like random noise. Therefore, pilot signals of signals from different groups of transmission apparatuses can be removed. If a group match, PRBS bit sequence W _i are equal, the result of the multiplication, an appropriate pilot signal is obtained.

Channel estimation unit 48, based on the transmission path like the estimation unit 67, W _i obtained from the multiplication unit 47 scattered pilot (SP) signal and / or continuous Al pilot (CP) signal of FIG. 6 Thus, the transmission characteristics of the signal transmission path are estimated.

Thereafter, the division unit 49 divides the main line received signal by the estimated transmission path characteristic to obtain a main line demodulated signal. Further, TMCC signal reproducing unit 50 reproduces the TMCC signal obtained from _{W i} multiplier 47, and extracts a synchronization signal and a control signal or the like.

  The subsequent processing is basically the same as the processing of the receiving apparatus in FIG.

  As described above, according to the OFDM receiving apparatus according to Embodiment 2, it is possible to identify the pilot signal of the OFDM modulated signal transmitted from the transmitting apparatus having the same group number, and to accurately estimate the transmission path characteristics. .

  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.

DESCRIPTION OF SYMBOLS 11 OFDM frame structure part 12 Scattered pilot (SP) production | generation part 13 Continuous pilot (CP) production | generation part 14 TMCC production | generation part 15 Group number setting part 16 Initial value generation part 17 _Wi multiplication part 21 Shift register 22 Exclusive logic Sum 23 Shift register output 41 FFT unit 42 Scattered pilot (SP) separation unit 43 Continuous pilot (CP) separation unit 44 TMCC separation unit 45 Group number setting unit 46 Initial value generation unit 47 _Wi multiplication unit 48 Transmission path characteristics Estimating unit 49 Dividing unit 50 TMCC signal reproducing unit 51 Energy spreading unit 52 Outer code encoding unit 53 Inner code encoding unit 54 Carrier modulation unit 55 Frequency interleaving unit 56 Pilot signal generating unit 57 TMCC signal generating unit 58 OFDM frame configuration unit 59 IFFT part 6 0 guard interval adding unit 61 guard interval removing unit 62 FFT unit 63 scattered pilot (SP) separating unit 64 continuous pilot (CP) separating unit 65 TMCC separating unit 66 Wi multiplying unit 67 transmission path characteristic estimating unit 68 TMCC signal regeneration Unit 69 division unit 70 frequency deinterleaving unit 71 carrier demodulation unit 72 inner code decoding unit 73 outer code decoding unit 74 energy despreading unit

Claims (4)

The output bit string Wi of the PRBS generation circuit is multiplied by at least one of a scattered pilot (SP) reference signal, a continuous pilot (CP) reference signal, and a TMCC signal, and the multiplied signal is multiplied by a predetermined OFDM frame signal. In an OFDM modulation scheme transmission device arranged at a position,
A group number setting unit capable of setting a desired group number; and an initial value generating unit for generating an initial value of the PRBS generation circuit corresponding to the set group number, and an output bit string Wi of the PRBS generation circuit For each group number ,
The synchronization signal of the TMCC signal is set such that a pattern of a synchronization signal that differs for each group number is set according to the setting of the group number, and the synchronization signal is not multiplied by the output bit string Wi. apparatus. The output bit string Wi of the PRBS generation circuit is multiplied by at least one of a scattered pilot (SP) reference signal, a continuous pilot (CP) reference signal, and a TMCC signal, and the multiplied signal is multiplied by a predetermined OFDM frame signal. In an OFDM modulation scheme transmission device arranged at a position,
A group number setting unit capable of setting a desired group number; and an initial value generating unit for generating an initial value of the PRBS generation circuit corresponding to the set group number, and an output bit string Wi of the PRBS generation circuit For each group number,
The synchronization signal of the TMCC signal is a basic pattern signal common to the group numbers, and the basic pattern signal is multiplied by the output bit string Wi to generate a different synchronization signal for each group number. A transmitting device characterized. At least one of a scattered pilot (SP) signal, a continuous pilot (CP) signal, and a TMCC signal is separated from a received signal subjected to FFT (Fast Fourier Transform) processing, and a PRBS generation circuit is separated into the separated signal. In the receiving apparatus of the OFDM modulation scheme that multiplies the output bit string Wi of, and estimates transmission path characteristics or extracts a synchronization signal and a control signal based on the multiplied signal,
A group number setting unit capable of setting a desired group number; and an initial value generating unit for generating an initial value of the PRBS generation circuit corresponding to the set group number, and an output bit string Wi of the PRBS generation circuit For each group number,
In the synchronization signal of the TMCC signal included in the reception signal, a different synchronization signal pattern is set for each group number according to the group number setting, and the synchronization signal is multiplied by the output bit string Wi. The receiving apparatus is configured to synchronize based on a synchronization signal pattern that is different for each group number . At least one of a scattered pilot (SP) signal, a continuous pilot (CP) signal, and a TMCC signal is separated from a received signal subjected to FFT (Fast Fourier Transform) processing, and a PRBS generation circuit is separated into the separated signal. In the receiving apparatus of the OFDM modulation scheme that multiplies the output bit string Wi of, and estimates transmission path characteristics or extracts a synchronization signal and a control signal based on the multiplied signal,
  A group number setting unit capable of setting a desired group number; and an initial value generating unit for generating an initial value of the PRBS generation circuit corresponding to the set group number, and an output bit string Wi of the PRBS generation circuit For each group number,
  The synchronization signal of the TMCC signal included in the received signal is obtained by multiplying the basic pattern signal common to the group numbers by the output bit string Wi and generating a different synchronization signal for each group number. There is provided a receiving apparatus which performs synchronization based on a different synchronization signal for each group number.

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