CN1980217A - Transmitting method, receiving method, transmitting apparatus and receiving apparatus - Google Patents

Abstract

In the OFDM transmission method of the present invention, the received OFDM signal is transformed from the time domain to the frequency domain through Fourier transform (12), so as to obtain the vector string of each carrier in the frequency domain. Extract the necessary scattered and terminal pilot signals (13) from the vector string, divide (15) by the demodulated complex number vector, estimate the transmission path characteristics related to the scattered/terminal pilot signals, and interpolate the transmission path characteristics Complement (16) to estimate the transmission path characteristics related to the information transmission carrier of the segment for coherent detection. On the other hand, the vector sequence obtained by Fourier transform is delayed by one symbol (17), and in the case of the segment for synchronous detection, the interpolation output is selected, and in the case of the segment for differential detection, the delayed output is selected. (18) Divide the selected output by the vector string, perform synchronous detection or differential detection (19), and demodulate to obtain digital information (20). This enables high-quality demodulation and demodulation suitable for mobile reception.

Description

Sending method, receiving method, sending device, receiving device

This application is a divisional application of the application filed on November 10, 2005 with the application number 200510120450.5 and the title of the invention is "transmitting method, receiving method, sending device, receiving device".

technical field

The present invention relates to an orthogonal frequency division multiplexing transmission method in which signals suitable for fixed reception and mobile reception are mixed and transmitted in one channel. Furthermore, it relates to a transmitting device that forms and transmits an OFDM signal based on the orthogonal frequency division multiplexing method, and a receiving device that receives and demodulates the OFDM signal formed and transmitted based on the orthogonal frequency division multiplexing method.

Background technique

At present, the use of orthogonal frequency division multiplexing (hereinafter referred to as OFDM) technology has been studied as a digital broadcasting system in terrestrial TV broadcasting. This OFDM transmission scheme is a type of multi-carrier modulation scheme, and digital information is transmitted by modulating a plurality of carriers having a mutually orthogonal frequency relationship for each symbol. In this method, digital information is divided into multiple carriers and transmitted as described above. Therefore, the length of the symbol period of the divided digital information used to modulate one carrier becomes longer, and it is difficult to be affected by delay waves such as multipath. nature.

As an existing digital broadcasting method of TV signals using OFDM transmission technology, the European DVB-T standard, namely ETSI 300 744 (ETSI: European Telecommunications Standards Institute), can be cited.

The existing OFDM transmission method uses 1705 carrier carriers in the entire transmission frequency band through, for example, 2k mode (2k represents that the sampling number of the high-speed Fourier transform when generating the OFDM signal is 2048), wherein 142 carrier carriers are used for Scattered pilot (Scattered Pilot) signal, use 45 carriers for continuous pilot (Continual Pilot) signal, use 17 carriers for control information (TPS), use 1512 carriers for information transmission Signal.

However, among the continuation pilot signals of 45 carriers, the continuation pilot signals of 11 carriers overlap with the scattered pilots. In addition, the frequency arrangement within one symbol of the scattered pilot signal is arranged in 12 carrier periods, the frequency arrangement is shifted every 3 carriers for each symbol, and the time arrangement is 4 symbol periods.

Specifically, the carrier number k is set from 0 to 1704 in order from one end, and the symbol number n in the frame is set to be from 0 to 67. At this time, the scattered pilot signal is arranged on the carrier number k in the formula (1) in the carrier. In formula (1), mod represents a remainder operation, and p is an integer ranging from 0 to 141.

k=3(n mod 4)+12p (1)

Continuous pilot signals are configured at carrier numbers k={0, 48, 54, 87, 141, 156, 192, 201, 255, 279, 282, 333, 432, 450, 483, 525, 531, 618, 636, 714, 759, 765, 780, 804, 873, 888, 918, 939, 942, 969, 984, 1050, 1101, 1107, 1110, 1137, 1140, 1146, 1206, 1269, 1323, 1377, 1491, 1683, 1704} in the carrier.

These scattered and continuous pilot signals are obtained by modulating a carrier with a complex number vector c _kn shown in equation (2) according to a PN (pseudo-random number) series w _k corresponding to a respectively configured carrier number k. In the formula (2), Re{c _kn } represents the real part of the complex vector c _kn corresponding to the carrier of carrier number k and symbol number n, and Im{c _kn } represents the imaginary part.

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

And, the control information signal called TPS (Transmission Parameter Signaling, sending parameter signal) is configured in the carrier number k={34, 50, 209, 346, 413, 569, 595, 688, 790, 901, 1073, 1219 , 1262, 1286, 1469, 1594, 1687} in the carriers, each symbol transmits 1 bit of control information.

When the control information bit transmitted by the symbol number n is Sn, the control information signal is obtained by modulating the carrier wave with the complex vector ck,n shown in the formula (3). That is, the carrier for transmitting the control information signal is subjected to differential binary PSK (Phase Shift Keying, frequency shift keying) modulation between symbols.

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; \&Right\; Arrow;</span>\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \}</span>\\ \mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.\\ {\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \&Right\; Arrow;</span>\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \}</span>\\ \mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

However, in the head symbol (symbol number n=0) of a frame, the carrier for transmitting control information is modulated by the complex vector ck,n shown in equation (4) based on the above-mentioned PN series Wk.

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

Carriers of 1512 carriers used for information transmission signals other than the above carriers are QPSK, 16QAM or 64QAM modulated according to digital information. Any modulation method is absolute phase modulation.

FIG. 10 shows an example of a conventional receiving apparatus that receives the thus-generated OFDM signal and demodulates digital information.

In FIG. 10, a received OFDM signal is frequency-converted by a tuner 101 and time-frequency-converted by a Fourier transform circuit 102 to become a vector sequence for each carrier in the carrier region. This vector string is supplied to the scattered pilot extraction circuit 103 and the continual pilot extraction circuit 109 .

Scattered pilot extraction circuit 103 extracts scattered pilot signals from the vector string output from Fourier transform circuit 102 . The vector generation circuit 104 generates a modulated complex vector c _k,n corresponding to the scattered pilot signal extracted by the scattered pilot extraction circuit 103 . The dividing circuit 105 divides the scattered pilot signal extracted by the scattered pilot extracting circuit 103 by the complex vector generated by the vector generating circuit 104, and estimates the propagation path characteristic related to the scattered pilot signal from the division result.

The interpolation circuit 106 interpolates the channel characteristics related to the scattered pilot signals obtained by the dividing circuit 105 to estimate the channel characteristics related to all the carriers. The division circuit 107 divides the vector sequence output from the Fourier transform circuit 102 by the channel characteristics estimated by the interpolation circuit 106 associated with the corresponding carriers to perform coherent detection. The demodulation circuit 108 demodulates the synchronous detection signal output from the division circuit 107 according to the modulation method (QPSK, 16QAM, 64QAM, etc.) when generating the information transmission signal, and obtains the transmitted digital information.

The continuation pilot extraction circuit 109 extracts continuation pilot signals from the vector string output from the Fourier transform circuit 102 . The vector generation circuit 110 generates a modulated complex vector c _k,n corresponding to the continuation pilot signal extracted by the continuation pilot extraction circuit 109 . The division circuit 111 divides the continuation pilot signal extracted by the continuation pilot extraction circuit 109 by the complex vector generated by the vector generation circuit 110 to estimate the channel characteristics related to the continuation pilot signal. The inverse Fourier transform circuit 112 performs frequency-time conversion on the channel characteristics associated with the continuation pilot signal estimated by the dividing circuit 111 to obtain the impulse response characteristics of the channel.

However, the premise of the existing OFDM transmission method is to use the transmission path characteristics obtained by performing absolute phase modulation by QPSK, 16QAM, 64QAM, etc. on the modulation of the carrier for transmitting digital information, and smooth interpolation for the demodulation. Since channel characteristics are estimated from temporally sparse scattered pilot signals, sufficient transmission quality may not be obtained in mobile communications in which channel characteristics change rapidly due to fading or the like.

Furthermore, in the conventional OFDM transmission method, one modulation method is specified for each carrier in the entire frequency band. Therefore, in order to be able to receive part of the digital information while moving, an appropriate modulation method is introduced into the modulation of the carrier that transmits the digital information. For mobile reception, for example, differential QPSK modulation, even so, the overall transmission capacity decreases and the efficiency deteriorates.

Furthermore, since the continuation pilot signal is placed on any one of the carriers at the predetermined carrier interval A, the effective symbol period length (minimum The reciprocal of the frequency interval) folds back one part of A.

Therefore, in order to solve the above-mentioned problems, the object of the present invention is to provide an OFDM method and a transmitting device and a receiving device suitable for the method, and the OFDM method can not only maintain the overall transmission capacity but also partially maintain the modulation of the carrier wave for transmitting digital information. A modulation method suitable for mobile reception can be introduced without delay, and continuous pilot signals can be arranged without turning back in the impulse response of the transmission path estimated from the continuous pilot signals.

Contents of the invention

Therefore, in order to solve the above-mentioned problems, the object of the present invention is to provide an OFDM method and a transmitting device and a receiving device suitable for the method, and the OFDM method can not only maintain the overall transmission capacity but also partially maintain the modulation of the carrier wave for transmitting digital information. A modulation method suitable for mobile reception can be introduced without delay, and continuous pilot signals can be arranged without turning back in the impulse response of the transmission path estimated from the continuous pilot signals.

In order to solve the above problems, the present invention provides a transmission method for transmitting digital information as an OFDM signal, characterized in that the OFDM signal includes two or more segments composed of multiple carriers with continuous frequencies , the segment is any one of a segment for coherent detection or a segment for differential detection, and the segment for coherent detection includes a carrier to which an additional information transmission signal is allocated and a carrier to which an information transmission signal is allocated, In the sector for coherent detection, the additional information transmission signal is allocated to a specific carrier, and in the sector for coherent detection, the information transmission signal is allocated to a carrier to which the additional information transmission signal is allocated. An arbitrary carrier other than a carrier, the segment for differential detection includes a carrier to which an additional information transmission signal is allocated and a carrier to which an information transmission signal is allocated, and in the segment for differential detection, the additional information transmission A signal is allocated to a specific carrier, and in the differential detection segment, the information transmission signal is allocated to any carrier other than the carrier to which the additional information transmission signal is allocated, the differential detection segment The position of the carrier to which the additional information transmission signal is allocated in the above segment including the position of the carrier to which the additional information transmission signal is allocated in the segment for coherent detection, the information transmission signal of the segment for coherent detection, The respective allocated carriers are subjected to absolute phase modulation based on the digital information, and the information transmission signal of the differential detection segment is differentially modulated based on the digital information.

Preferably, in the above sending method, the absolute phase modulation is any one of QPSK modulation, 16QAM modulation, and 64QAM modulation.

Preferably, in the above sending method, the differential modulation is DQPSK modulation.

Preferably, in the above sending method, the additional information transmission signal performs differential modulation on the respective allocated carriers according to the additional information.

Preferably, in the above transmission method, the differential modulation with respect to the additional information transmission signal is DBPSK modulation.

The present invention also provides a receiving method for receiving OFDM signals and restoring digital information, characterized in that the OFDM signal includes two or more sections composed of multiple carriers with continuous frequencies, and the sections , which is any one of a segment for coherent detection or a segment for differential detection, the segment for coherent detection includes a carrier to which an additional information transmission signal is allocated and a carrier to which an information transmission signal is allocated, and in the coherent detection In the segment for the additional information transmission signal is allocated to a specific carrier, in the segment for coherent detection, the information transmission signal is allocated to any carrier other than the carrier to which the additional information transmission signal is allocated , the section for differential detection includes a carrier to which an additional information transmission signal is allocated and a carrier to which an information transmission signal is allocated, and in the section for differential detection, the additional information transmission signal is allocated to a specific In the segment for differential detection, the information transmission signal is assigned to any carrier other than the carrier to which the additional information transmission signal is assigned, and the segment for differential detection is assigned the The position of the carrier of the additional information transmission signal includes the position of the carrier of the additional information transmission signal allocated in the sector for coherent detection, the information transmission signal of the sector for coherent detection is based on the digital information Absolute phase modulation is performed on the respective allocated carriers, the information transmission signal of the differential detection section is differentially modulated on the basis of the digital information, and the OFDM signal is After the Fourier transform, coherent detection is performed on the segment for coherent detection, and differential detection is performed on the segment for differential detection, thereby restoring the digital information.

Preferably, in the above receiving method, the absolute phase modulation is any one of QPSK modulation, 16QAM modulation, and 64QAM modulation.

Preferably, in the above receiving method, the differential modulation is DQPSK modulation.

Preferably, in the above receiving method, the additional information transmission signal performs differential modulation on the respective allocated carriers according to the additional information.

Preferably, in the above receiving method, the differential modulation with respect to the additional information transmission signal is DBPSK modulation.

The present invention also provides a transmission device for transmitting digital information as an OFDM signal, which is characterized in that it includes: a carrier allocation device for distributing the information transmission signal and the additional information transmission signal to a predetermined carrier; and an inverse Fourier transform device, The OFDM signal is generated by performing an inverse Fourier transform on the output of the carrier configuration device, the OFDM signal includes 2 or more sections composed of multiple carriers with continuous frequencies, and the sections, It is any one of a segment for coherent detection or a segment for differential detection, and the segment for coherent detection includes a carrier to which an additional information transmission signal is assigned and a carrier to which an information transmission signal is assigned, and the segment for coherent detection In the segment, the additional information transmission signal is allocated to a specific carrier, in the coherent detection segment, the information transmission signal is allocated to any carrier other than the carrier to which the additional information transmission signal is allocated, The segment for differential detection includes a carrier to which an additional information transmission signal is allocated and a carrier to which an information transmission signal is allocated, and in the segment for differential detection, the additional information transmission signal is allocated to a specific In the segment for differential detection, the information transmission signal is assigned to any carrier other than the carrier to which the additional information transmission signal is assigned, and the additional information transmission signal is assigned to the segment for differential detection. The position of the carrier of the information transmission signal includes the position of the carrier of the additional information transmission signal allocated in the sector for coherent detection, the information transmission signal of the sector for coherent detection is based on the digital information pair The respective allocated carriers are subjected to absolute phase modulation, and the information transmission signal of the segment for differential detection is differentially modulated based on the digital information.

Preferably, in the above sending device, the absolute phase modulation is any one of QPSK modulation, 16QAM modulation, and 64QAM modulation.

Preferably, in the above sending device, the differential modulation is DQPSK modulation.

Preferably, in the above sending device, the additional information transmission signal differentially modulates the respective allocated carriers according to the additional information.

Preferably, in the above transmitting device, the differential modulation with respect to the additional information transmission signal is DBPSK modulation.

The present invention also provides a receiving device for receiving OFDM signals and restoring digital information, characterized in that the OFDM signal includes two or more sections composed of multiple carriers with continuous frequencies, and the sections , which is any one of a segment for coherent detection or a segment for differential detection, the segment for coherent detection includes a carrier to which an additional information transmission signal is allocated and a carrier to which an information transmission signal is allocated, and in the coherent detection In the segment for the additional information transmission signal is allocated to a specific carrier, in the segment for coherent detection, the information transmission signal is allocated to any carrier other than the carrier to which the additional information transmission signal is allocated , the section for differential detection includes a carrier to which an additional information transmission signal is allocated and a carrier to which an information transmission signal is allocated, and in the section for differential detection, the additional information transmission signal is allocated to a specific In the segment for differential detection, the information transmission signal is assigned to any carrier other than the carrier to which the additional information transmission signal is assigned, and the segment for differential detection is assigned the The position of the carrier of the additional information transmission signal includes the position of the carrier of the additional information transmission signal allocated in the sector for coherent detection, the information transmission signal of the sector for coherent detection is based on the digital information Absolute phase modulation is performed on the respective allocated carriers, the information transmission signal of the differential detection section is differentially modulated according to the digital information, and the receiving device includes: Fourier transforming means for performing Fourier transform on said OFDM signal, and detection means for performing synchronous detection on said segments for coherent detection and differential detection on said segments for differential detection within the output of said Fourier transform means detection.

Preferably, in the above receiving device, the absolute phase modulation is any one of QPSK modulation, 16QAM modulation, and 64QAM modulation.

Preferably, in the above receiving device, the differential modulation is DQPSK modulation.

Preferably, in the above receiving device, the additional information transmission signal differentially modulates the respective allocated carriers according to the additional information.

Preferably, in the above receiving device, the differential modulation with respect to the additional information transmission signal is DBPSK modulation.

Description of drawings

These and other objects, advantages and features of the present invention will be further clarified by describing the embodiments of the present invention with reference to the accompanying drawings. In these drawings:

Fig. 1 is a diagram showing an arrangement example of segments for synchronous detection or differential detection (13 segments in total) and band terminal pilot signals in the first and second embodiments of the OFDM transmission system according to the present invention. picture;

FIG. 2 shows the arrangement of additional information transmission signals, the arrangement of scattered pilot signals in the segment for coherent detection, and the arrangement of scattered pilot signals in the segment for differential detection in the first and second embodiments of the OFDM transmission system according to the present invention. A diagram of a configuration example of a terminal pilot signal;

FIG. 3 shows the arrangement of continuous pilot signals and control information signals, the arrangement of scattered pilot signals in the segment for coherent detection, and the segment for differential detection in the second embodiment of the OFDM transmission system according to the present invention. A diagram of a configuration example of a terminal pilot signal in ;

FIG. 4 is a time-amplitude characteristic diagram showing an inverse Fourier transform pair of frequency assignments of continuous pilot signals in the coherent detection segment shown in Table 2 in the second embodiment of the OFDM transmission method according to the present invention;

Fig. 5 shows a time-amplitude characteristic diagram of an inverse Fourier transform pair of frequency assignments of continuous pilot signals in the differential detection segment shown in Table 2 in the second embodiment of the OFDM transmission method according to the present invention;

FIG. 6 is a time-amplitude characteristic diagram showing an inverse Fourier transform pair of the frequency arrangement of the control information signal of the coherent detection segment shown in Table 3 in the second embodiment of the OFDM transmission method according to the present invention;

FIG. 7 is a time-amplitude characteristic diagram of an inverse Fourier transform pair showing the frequency arrangement of the control information signal of the differential detection segment shown in Table 3 in the second embodiment of the OFDM transmission method according to the present invention;

FIG. 8 is a block circuit diagram showing the configuration of a transmission device used in the OFDM transmission method according to the present invention as a fifth embodiment;

FIG. 9 is a block circuit diagram showing the configuration of a receiving device used in the OFDM transmission method according to the present invention as a sixth embodiment;

FIG. 10 is a block circuit diagram showing the configuration of a receiving device used in a conventional OFDM transmission system.

Detailed ways

Embodiments of the OFDM transmission mode involved in the present invention and the transmitting device and receiving device suitable for the OFDM transmission mode will be described in detail below.

first embodiment

In the OFDM transmission scheme of this embodiment, it consists of 13 segments and band terminal pilots using one carrier, and one segment is composed of 108 carriers. Each segment is constituted by either a segment for synchronous detection or a segment for differential detection. 1405 carriers are used in the entire frequency band.

FIG. 1 shows an example of arrangement of coherent detection or differential detection segments (13 segments in total) and band terminal pilot signals. The horizontal axis represents the frequency axis (carrier arrangement), and the vertical axis represents the time axis (symbol direction). Assuming that the carrier number k' in each segment is an integer from 0 to 107, one segment consists of 108 carriers.

The coherent detection segment is composed of scattered pilot signals using 9 carriers per symbol, additional information transmission signals using 3 carriers, and information transmission signals using 96 carriers.

The differential detection segment is composed of an additional information transmission signal using 11 carriers, a terminal pilot signal using 1 carrier, and an information transmission signal using 96 carriers.

Thus, since 108 carriers of the same number are used in the coherent detection segment and the differential detection segment, the required transmission frequency band cannot be changed by combination of segments.

Wherein, the carrier number k in the entire frequency band is an integer from 0 to 1404, the section number i is an integer from 0 to 12, and the carrier number k' in each section is an integer from 0 to 107, then k=i is satisfied • 108+k'.

The scattered pilot signals provided in the coherent detection segments are arranged in each segment and the carrier of the carrier number k' within the segment generated by Equation (5). In the formula (5), mod represents a remainder operation, n representing a symbol number is an integer not less than 0, and p is an integer not less than 0 and not more than 8.

k′＝3(n mod 4)+12p (5)

The additional information transmission signals provided in the coherent detection segment and the differential detection segment are arranged on carriers of carrier number k' in each segment shown in Table 1, respectively. Table 1 shows that the additional information transmission signal of the sector for coherent detection is included in the additional information transmission signal of the sector for differential detection.

With the above configuration, even in the state where the coherent detection sector and the differential detection sector are mixed, the additional information transmission signal must be placed on the carrier defined as the additional information transmission signal of the coherent detection sector. The receiving side can easily identify the additional information transmission signal or other transmission signals. Also, the carriers are allocated by the transmitted additional information so as not to become a partial set configuration.

Table 1 Frequency configuration of additional information transmission signals

Section number i Carrier number k’ For synchronous detection For differential detection No.0 1050 28 313 1050 2870 4583 5987 77 No.1 5325 83 325 1563 4073 5380 5893 83 No.2 6171 100 294 417 6117 8451 9371 100 No.3 1155 101 113 2848 4555 8159 9186 101 No.4 2044 40 2010 2328 4044 6347 8554 105 No.5 7425 100 307 7425 8147 9260 10087 103 No.6 3549 79 349 3561 7296 7999 85104 89 No.7 7665 97 531 1839 5747 7665 9272 97 No.8 474 89 416 1330 8937 9374 9883 102 No.9 405 89 405 7210 8921 9544 10061 105 No.10 885 64 878 3682 4885 5298 64102 74 No.11 770 89 734 2548 3054 4270 89101 104 No.12 9837 101 1023 3037 5551 8168 98105 101

The terminal pilot signals provided in the sectors for differential detection are arranged on the carrier whose carrier number k' is 0 in each sector. The arrangement of terminal pilot signals is a position where the periodicity of the frequency arrangement of scattered pilot signals of adjacent coherent detection segments is maintained. Each terminal pilot signal complements the scattered pilot signal.

FIG. 2 shows an example of the arrangement of scattered pilot signals in the coherent detection segment and the arrangement of terminal pilot signals in the differential detection segment. The horizontal axis represents the frequency axis (carrier arrangement), and the vertical axis represents the time axis (symbol direction). Assuming that the carrier number k' in each segment is an integer from 0 to 107, one segment consists of 108 carriers. The additional information transmission signal is assigned to a carrier different from the scattered pilot signal.

These scattered pilot signals and terminal pilot signals are respectively based on the PN (pseudo-random number) series w _k (w _k =0, 1) and obtained by modulating the carrier wave with the complex vector c _k,n shown in the formula (6). In formula (6), Re{c _k,n } represents the real number part of the complex vector c _k,n corresponding to the carrier of carrier number k and symbol number n, and Im{c _k,n } represents the imaginary part.

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

The additional information transmission signals provided in the coherent detection sector and the differential detection sector are used to transmit additional information different from the information transmission signals transmitted using 96 carriers. For example, consider control information defining a transmission method (number of segments, carrier modulation method, etc.) and information used as a broadcasting station (for example, control information used in a relay station, a signal for identifying a broadcasting station, etc.). One bit of additional information may be transmitted in each symbol, or multiple bits of additional information may be transmitted. Only control information specifying the transmission method may be transmitted.

Wherein, when the control information bit transmitted by the symbol of symbol number n is Sn, the control information signal is obtained by modulating the carrier wave with the complex vector c _k,n shown in the formula (7). That is, in this case, the carrier for transmitting the control information signal is subjected to differential binary PSK (PhaseShift Keying) modulation between symbols.

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; \&Right\; Arrow;</span>\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \}</span>\\ \mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.\\ {\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \&Right\; Arrow;</span>\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \}</span>\\ \mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

However, in the first symbol (symbol number n=0) of the frame, the carrier for transmitting the control information is modulated by the complex vector c _k,n shown in equation (8) according to the above-mentioned PN sequence w _k .

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

Moreover, in the case of transmitting 2-bit control information in each symbol, for example, differential 4-phase PSK modulation between symbols can be used, or a plurality of carriers for transmitting control information can be divided into 2 groups, and allocated as 1 bit is transmitted in each symbol.

The information transmission signal provided in the sector for coherent detection is assigned to a carrier other than the scattered pilot signal and the additional information transmission signal of the sector for coherent detection, and absolute phase modulation is performed based on digital information. For this absolute phase modulation, for example, QPSK, 16QAM, 64QAM modulation, etc. are used.

The information transmission signal of the coherent detection segment is demodulated by the following process. First, demodulate the scattered pilot signal, the necessary terminal pilot signal, and the frequency band terminal pilot signal by modulating the scattered pilot signal, the terminal pilot signal and the complex vector of the frequency band terminal pilot signal, and obtain the scattered pilot signal Transmission path characteristics in the frequency domain related to signals and terminal pilot signals etc. Furthermore, a filter is used to perform interpolation in the frequency direction and the symbol direction to estimate the channel characteristics related to the information transmission signal. The thus obtained transmission path characteristic is divided by the information transmission signal. Thereby, the information transmission signal can be demodulated from the sector for coherent detection.

The information transmission signal in the differential detection segment is assigned to a carrier other than the terminal pilot signal and the additional information transmission signal in the differential detection segment, and adjacent codes of the same carrier number are assigned based on digital information. Differential modulation between elements.

For this differential modulation, for example, DBPSK, DQPSK, DAPSK, etc. are used. Demodulation can be performed by dividing the information transmission signal of the same carrier number of the above-mentioned symbol by the information transmission signal of the segment for differential detection.

As described above, in the OFDM transmission system of this embodiment, in the receiving apparatus, high-quality reception can be achieved by the effect of the filter in the sector for synchronous detection, and by the effect of the inter-symbol error in the sector for differential detection. Differential demodulation is used to perform reception suitable for mobile reception where channel characteristics change rapidly. Furthermore, by arbitrarily combining a sector for coherent detection and a sector for differential detection in each sector, it is possible to realize a flexible service state that does not vary depending on the transmission band.

second embodiment

In the OFDM transmission scheme of this embodiment, it consists of 13 segments and band terminal pilots using one carrier, and one segment is composed of 108 carriers. Each segment is constituted by either a segment for synchronous detection or a segment for differential detection. 1405 carriers are used in the entire frequency band.

The coherent detection sector consists of scattered pilot signals using 9 carriers per symbol, continuous pilot signals using 2 carriers, and additional information transmission signals using 1 carrier (in this embodiment In, it is called control information signal), and it is composed of information transmission signal using 96 carrier waves.

The differential detection segment consists of continuous pilot signals using 6 carriers, control information signals using 5 carriers, terminal pilot signals using 1 carrier, and carrier information using 96 carriers. composed of transmitted signals.

Wherein, the carrier number k in the entire frequency band is an integer from 0 to 1404, the section number i is an integer from 0 to 12, and the carrier number k' in each section is an integer from 0 to 107, then k=i is satisfied • 108+k'.

The scattered pilot signals provided in the coherent detection segments are arranged in each segment and the carrier of the carrier number k' within the segment generated by Equation (5). In the formula (5), mod represents a remainder operation, n representing a symbol number is an integer of 0 or more, and p is an integer of 0 or more and 8 or less.

k′＝3(n mod 4)+12p (5)

The continuation pilot signals provided in the coherent detection segment and the differential detection segment are arranged on the carriers of the carrier number k' in each segment shown in Table 2, respectively. Table 2 shows that the continuation pilot signals of the coherent detection segment are included in the continuation pilot signals of the differential detection segment.

Table 2 Frequency configuration of continuous pilot signals

Section number i Carrier number k’ For synchronous detection For differential detection No.0 10 28 3 10 28 45 59 77 No.1 53 83 3 15 40 53 58 83 No.2 61 100 29 41 61 84 93 100 No.3 11 101 11 28 45 81 91 101 No.4 20 40 20 twenty three 40 63 85 105 No.5 74 100 30 74 81 92 100 103 No.6 35 79 3 35 72 79 85 89 No.7 76 97 5 18 57 76 92 97 No.8 4 89 4 13 89 93 98 102 No.9 40 89 40 72 89 95 100 105 No.10 8 64 8 36 48 52 64 74 No.11 7 89 7 25 30 42 89 104 No.12 98 101 10 30 55 81 98 101

With the above configuration, even in the state where the coherent detection sector and the differential detection sector are mixed, the continuous pilot signal must be arranged in the continuous pilot carrier defined as the coherent detection sector, and the receiving side Identification of continuous pilot signals or other transmitted signals is easily performed. Also, carriers can be allocated so as not to be a partial set configuration.

In a carrier having the same frequency as each symbol, a continuous pilot signal that modulates the carrier with a specific phase and amplitude can be used as a reference carrier on the receiving side because the frequency, phase, and amplitude are designated.

It is assumed that the terminal pilot signals in the sectors for differential detection are arranged on the carrier whose carrier number k' is 0 in each sector. The arrangement of terminal pilot signals is a position where the periodicity of the frequency arrangement of adjacent coherent detection segment scattered pilot signals is maintained. Each terminal pilot signal complements the scattered pilot signal.

FIG. 3 shows an example of the arrangement of continuous pilot signals and control information signals, the arrangement of scattered pilot signals in the coherent detection segment, and the arrangement of terminal pilot signals in the differential detection segment. The horizontal axis represents the frequency axis (carrier arrangement), and the vertical axis represents the time axis (symbol direction). Assuming that the carrier number k' in each segment is an integer from 0 to 107, one segment consists of 108 carriers. Continuous pilot signals and control information signals are allocated to different carriers from scattered pilot signals.

These scattered pilot signals, continuous pilot signals and terminal pilot signals are respectively based on the PN (pseudo-random number) corresponding to the configured carrier number k (determined by the segment number i and the carrier number k' in each segment) The series w _k (w _k =0, 1) is obtained by modulating the carrier wave with the complex vector c _k,n shown in the formula (6). In formula (6), Re{c _k,n } represents the real number part of the complex vector c _k,n corresponding to the carrier of carrier number k and symbol number n, and Im{c _k,n } represents the imaginary part.

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

Assume that the control information signals in the coherent detection segment and the differential detection segment are arranged on carriers of carrier number k' in each segment shown in Table 3, and a 1-bit signal is transmitted per symbol. control information.

Table 3 Frequency Configuration of Control Information Signals

Section number i Carrier number k’ For synchronous detection For differential detection No.0 50 13 50 70 83 87 No.1 25 25 63 73 80 93 No.2 71 4 7 17 51 71 No.3 55 36 48 55 59 86 No.4 44 10 28 44 47 54 No.5 25 7 25 47 60 87 No.6 49 49 61 96 99 104 No.7 65 31 39 47 65 72 No.8 74 16 30 37 74 83 No.9 5 5 10 twenty one 44 61 No.10 85 78 82 85 98 102 No.11 70 34 48 54 70 101 No.12 37 twenty three 37 51 68 105

When the control information bit transmitted by the symbol of symbol number n is Sn, the control information signal is obtained by modulating the carrier wave with the complex vector c _k,n shown in the formula (7). That is, the carrier for transmitting the control information signal is differentially binary PSK (Phase Shift Keying, Phase Shift Keying) modulation between symbols.

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; \&Right\; Arrow;</span>\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \}</span>\\ \mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.\\ {\mathrm{<span\; class="notranslate">\; S</span>}}_{\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \&Right\; Arrow;</span>\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \}</span>\\ \mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; no</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

However, in the first symbol (symbol number n=0) of the frame, the carrier for transmitting the control information is modulated by the complex vector c _k,n shown in equation (8) according to the above-mentioned PN sequence w _k .

$\left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; Re</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 4</span>}}{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; w</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; )</span>\\ \mathrm{<span\; class="notranslate">\; Im</span>}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

Furthermore, in the case of transmitting 2-bit control information per symbol, for example, differential 4-phase PSK modulation between symbols can be used.

The information transmission signal provided in the coherent detection sector is assigned to a carrier other than the scattered pilot signal, the continuous pilot signal, and the control information signal of the coherent detection sector, and absolute phase modulation is performed based on digital information. For this absolute phase modulation, for example, QPSK, 16QAM, 64QAM modulation, etc. are used.

The information transmission signal of the coherent detection segment is demodulated by the following process. First, the scattered pilot signal, the necessary terminal pilot signal, and the band terminal pilot signal are inversely modulated by the complex vector that modulates the scattered pilot signal, terminal pilot signal, and band terminal pilot signal, and the scattered pilot signal and the scattered pilot signal are estimated and Transmission path characteristics in the frequency domain related to signals and terminal pilot signals etc. Furthermore, a filter is used to perform interpolation in the frequency direction and the symbol direction to estimate the channel characteristics related to the information transmission signal. The thus obtained transmission path characteristic is divided by the information transmission signal. Thereby, the information transmission signal can be demodulated from the sector for coherent detection.

The information transmission signal provided in the differential detection segment is allocated to carriers other than the continuous pilot signal, the terminal pilot signal, and the control information signal of the above-mentioned differential detection segment, and the same carrier number is assigned based on digital information. Differential modulation is performed between adjacent symbols.

For this differential modulation, for example, DBPSK, DQPSK, DAPSK, etc. are used. Demodulation can be performed by dividing the information transmission signal of the same carrier number of the above-mentioned symbol by the information transmission signal of the segment for differential detection.

As described above, in the OFDM transmission system of this embodiment, in the receiving apparatus, high-quality reception can be achieved by the effect of the filter in the sector for synchronous detection, and by the effect of the inter-symbol error in the sector for differential detection. Differential demodulation is used to perform mobile reception suitable for rapidly changing transmission path characteristics. Furthermore, by arbitrarily combining a sector for coherent detection and a sector for differential detection in each sector, it is possible to realize a flexible service state that does not vary depending on the transmission band.

By arranging a continuous pilot signal modulating the carrier with a specific phase and amplitude in a carrier having the same frequency as each symbol, it is possible to determine the frequency, phase and amplitude by using it as a reference carrier.

Fig. 4 and Fig. 5 respectively show the continuation pilot signal of the segment for coherent detection (13 segments, 26 carriers) and the segment for differential detection (13 segments, 78 carriers) shown in Table 2. Inverse Fourier transform pair of frequency configurations. It can be seen from Fig. 4 and Fig. 5 that they are pulse-shaped, and the frequency configuration of the continuous pilot signal shown in Table 2 has no periodicity.

In this manner, the OFDM transmission scheme of this embodiment can prevent the overall fading of continuous pilot signals due to delayed waves such as multipath. By obtaining the inverse Fourier transform using this arrangement, the impulse response of the transmission line can be obtained. Furthermore, the frequency arrangement of the continuous pilot signals has a strong autocorrelation.

6 and 7 respectively show the inverse Fourier transform pairs of the frequency arrangement of the control information signal of the segment for synchronous detection and the segment for differential detection shown in Table 3. It can be seen from Fig. 6 and Fig. 7 that they are pulse-shaped, and the frequency configuration of the control information signal shown in Table 3 has no periodicity.

In this way, the OFDM transmission method of this embodiment can prevent the overall control information signal from fading due to delayed waves such as multipath.

Furthermore, the frequency arrangement of the additional information transmission signal including the control information signal can be similarly set.

third embodiment

FIG. 8 shows the configuration of an embodiment of a transmission device that generates OFDM signals according to the OFDM transmission schemes of the first and second embodiments.

In FIG. 8, the input digital information is subjected to error control processing (error correction coding and interleaving, energy dispersal, etc.) and digital modulation by an information transmission signal generation circuit 51 as necessary. Furthermore, the basic error control processing method and digital modulation method generally used in digital transmission are well-known technologies, and thus description thereof will be omitted.

Absolute phase modulation is performed as digital modulation in the coherent detection segment. In this absolute phase modulation, for example, QPSK, 16QAM, 64QAM modulation, etc. are used. In the differential detection segment, differential modulation is performed between adjacent symbols of the same carrier number based on digital information. For this differential modulation, for example, DBPSK, DQPSK, DAPSK, etc. are used.

The additional information signal generation circuit 52 performs error control processing (error correction coding and interleaving, energy dispersal, etc.) and digital modulation on the input additional information as necessary. As digital modulation, M (M is a natural number greater than 2) phase PSK (Phase Shift Keying) modulation and differential M-phase PSK modulation in the symbol direction are used.

The control information generation circuit 56 generates transmission method information (various information specifying transmission methods such as the number of segments for synchronous detection, the number of segments for differential detection, and the carrier modulation method) required on the receiving side. This information is subjected to error control processing and digital modulation by the additional information signal generating circuit 52, and may be subjected to error control processing and digital modulation different from other additional information.

The scattered pilot signal generating circuit 53 generates a PN (pseudo-random number) series wk( wk=0,1) modulated scattered pilot signal.

The terminal pilot signal generation circuit 54 generates a PN (pseudo-random number) series w _k corresponding to the carrier number k (determined by the segment number i and the carrier number k' in each segment) specified and configured by the carrier configuration circuit 57 (w _k =0, 1) modulated terminal pilot signal.

The band terminal pilot signal generation circuit 55 generates a band terminal pilot signal modulated by a PN (pseudo-random number) sequence w _k (w _k =0, 1) corresponding to the carrier number k of the band terminal.

Although the continuous pilot signal is not particularly described, it is conceivable that the additional information signal generating circuit 52 modulates the carrier with the same phase and amplitude for each symbol.

In the carrier arrangement circuit 57, each output of the information transmission signal generation circuit 51, the additional information signal generation circuit 52, the scattered pilot signal generation circuit 53, the terminal pilot signal generation circuit 54, and the band termination pilot signal generation circuit 55 ( complex vector sequence) is arranged at the carrier position in the frequency range specified by the transmission method.

For example, the output of the scattered pilot signal generation circuit 53 is arranged at N (N is a natural number greater than or equal to 2) carrier intervals in the coherent detection segment and shifted by L (L is approximately N) per symbol. number) in the carrier of the carrier. The output of the terminal pilot signal generation circuit 54 is arranged on a carrier of carrier number k'=0 in the segment for differential detection. Also, the output of the additional information signal generating circuit 52 is allocated in accordance with the frequency arrangement shown in Table 1, for example. The vector string for each carrier of the base band configured in this way is input to the inverse Fourier transform circuit 58 .

The inverse Fourier transform circuit 58 converts the vector sequence for each carrier of the baseband generated by the carrier arrangement circuit 57 from the frequency domain to the time domain, adds a guard interval period generally used, and outputs it. The quadrature modulation circuit 59 quadrature modulates the output of the inverse Fourier transform circuit 58 and converts it into an intermediate frequency band. The frequency conversion circuit 60 converts the frequency band of the orthogonally modulated OFDM signal from the intermediate frequency band to the radio frequency band, and supplies it to an antenna or the like.

According to the transmission device formed as above, it is possible to generate an OFDM signal according to the OFDM transmission method described in the first and second embodiments.

Fourth embodiment

FIG. 9 shows the configuration of a receiving device capable of receiving an OFDM signal formed by the OFDM transmission scheme according to the first and second embodiments and estimating the impulse response in the time domain of the transmission path.

In FIG. 9, tuner 11 converts the frequency band of the received OFDM signal from the radio frequency band to the base frequency band. The Fourier transform circuit 12 transforms the baseband OFDM signal from the time domain to the frequency domain, and outputs it as a vector sequence for each carrier in the frequency domain.

The scattered/terminal pilot extraction circuit 13 extracts scattered pilot signals, necessary terminal pilot signals, and band terminal pilot signals from the vector string output from the Fourier transform circuit 12 . The vector generation circuit 14 generates a modulated complex vector c _k,n corresponding to the scattered pilot signal, terminal pilot signal and band terminal pilot signal extracted by the scattered/terminal pilot extraction circuit 13 .

The division circuit 15 divides the scattered pilot signal, the terminal pilot signal, and the band terminal pilot signal extracted by the scattered/terminal pilot extraction circuit 13 by the complex vector generated by the vector generation circuit 14 to estimate the scattered pilot signal , the terminal pilot signal and the transmission path characteristics related to the band terminal pilot signal. The interpolation circuit 16 interpolates the transmission path characteristics related to the scattered pilot signal, the terminal pilot signal, and the band terminal pilot signal obtained by the dividing circuit 15 to estimate the correlation with the information transmission signal of the coherent detection segment. Carrier dependent transmission path characteristics.

The delay circuit 17 delays the vector train output from the Fourier transform circuit 12 by one symbol. The selection circuit 18 selects and outputs the output of the interpolation circuit 16 in the case of a segment for synchronous detection, and selects the output of the delay circuit 17 in the case of a segment for differential detection according to the type of the segment separately transmitted by the control information. And the output.

The division circuit 19 divides the vector sequence output from the Fourier transform circuit 12 by the output of the selection circuit 18 respectively. In the division circuit 19, in the section for coherent detection, the transmission path characteristics associated with the respective carriers estimated by the interpolation circuit 16 are used to perform a division operation to perform coherent detection, and in the section for differential detection, Differential detection is performed by performing division with the vector sequence corresponding to each carrier one symbol before the output from the delay circuit 17 .

The demodulation circuit 20 demodulates the detection signal output from the division circuit 19 according to the modulation method (QPSK, 16QAM, 64QAM, DBPSK, DQPSK, DAPSK, etc.) when generating the information transmission signal to obtain transmitted digital information.

With the above configuration, an OFDM signal can be received and demodulated according to the OFDM transmission method described in the first embodiment. The configuration described below is a case where an OFDM signal is received and demodulated according to the OFDM transmission method described in the second embodiment.

First, the continuation pilot extraction circuit 21 extracts continuation pilot signals from the vector string output from the Fourier transform circuit 12 . In this case, even when coherent detection segments and differential detection segments are mixed, at least continuous pilot signals in the coherent detection segments must be mixed, and continuous pilot signals can always be extracted.

The vector generation circuit 22 generates a modulated complex vector c _k,n corresponding to the continuation pilot signal extracted by the continuation pilot extraction circuit 21 . The division circuit 23 divides the continuation pilot signal extracted by the continuation pilot extraction circuit 21 by the complex number vector generated by the vector generation circuit 22 to estimate the transmission channel characteristics related to the continuation pilot signal. The inverse Fourier transform circuit 24 transforms the transmission path characteristics related to the continuous pilot signal obtained by the division circuit 23 from the frequency domain to the time domain to obtain the impulse response characteristics of the transmission path.

As described above, according to the configuration of the receiving apparatus of this embodiment, in the demodulation circuit 20, high-quality demodulation can be realized by the filter effect obtained by the interpolation processing of the transmission channel characteristics in the coherent detection segment. , demodulation suitable for mobile reception where channel characteristics change rapidly is realized by differential demodulation between symbols in the differential detection segment. Furthermore, in the inverse Fourier transform circuit 24, the impulse response characteristic of the transmission path without a turn-back can be obtained.

As described above, the OFDM transmission scheme of the present invention can have a sector for differential detection suitable for mobile reception. At this time, by having the terminal pilot signal and the band terminal pilot signal, it is possible to freely combine the coherent detection sector and the differential coherent detection sector for each sector without impairing the coherent detection characteristics of the adjacent coherent detection sectors. The section for wave detection can thereby realize a flexible service state.

The pulse-shaped continuous pilot signal can be obtained by inverse Fourier transform of the frequency allocation, and the impulse response characteristic without foldback can be obtained in the symbol period as needed.

Thus, according to the present invention, there are provided an OFDM method, which can partially introduce modulation suitable for mobile reception in the modulation of a carrier wave for transmitting digital information while maintaining the overall transmission capacity, and a transmitting device and a receiving device suitable for the method. modulation scheme, and the continuation pilot signal is arranged without turning back in the impulse response of the transmission path estimated from the continuation pilot signal, for example.

Claims (20)

1. A method for transmitting digital information as an OFDM signal, characterized in that, The OFDM signal includes 2 or more segments consisting of multiple carriers with continuous frequencies, The segment is either a segment for synchronous detection or a segment for differential detection, The coherent detection segment includes a carrier to which an additional information transmission signal is allocated and a carrier to which an information transmission signal is allocated, In the sector for coherent detection, the additional information transmission signal is allocated to a specific carrier, In the sector for coherent detection, the information transmission signal is allocated to any carrier other than the carrier to which the additional information transmission signal is allocated, The differential detection segment includes a carrier to which an additional information transmission signal is allocated and a carrier to which an information transmission signal is allocated, In the segment for differential detection, the additional information transmission signal is allocated to a specific carrier, In the segment for differential detection, the information transmission signal is allocated to any carrier other than the carrier to which the additional information transmission signal is allocated, The position of the carrier of the additional information transmission signal assigned to the segment for differential detection includes the position of the carrier of the additional information transmission signal assigned to the segment for coherent detection, The information transmission signal of the coherent detection segment absolute phase-modulates the respective assigned carriers according to the digital information, The information transmission signal of the segment for differential detection differentially modulates the carrier to which it is respectively assigned based on the digital information. 2. The sending method according to claim 1, characterized in that, The absolute phase modulation is any one of QPSK modulation, 16QAM modulation, and 64QAM modulation. 3. The sending method according to claim 1, characterized in that, The differential modulation is DQPSK modulation. 4. The sending method according to claim 1, characterized in that, The additional information transmission signal differentially modulates the respective allocated carriers according to the additional information. 5. The sending method according to claim 4, characterized in that, The differential modulation for the additional information transmission signal is DBPSK modulation. 6. A receiving method for receiving OFDM signals and restoring digital information, characterized in that, The OFDM signal includes 2 or more segments consisting of multiple carriers with continuous frequencies, The segment is either a segment for synchronous detection or a segment for differential detection, The coherent detection segment includes a carrier to which an additional information transmission signal is allocated and a carrier to which an information transmission signal is allocated, In the sector for coherent detection, the additional information transmission signal is allocated to a specific carrier, In the sector for coherent detection, the information transmission signal is allocated to any carrier other than the carrier to which the additional information transmission signal is allocated, The differential detection segment includes a carrier to which an additional information transmission signal is allocated and a carrier to which an information transmission signal is allocated, In the segment for differential detection, the additional information transmission signal is allocated to a specific carrier, In the segment for differential detection, the information transmission signal is allocated to any carrier other than the carrier to which the additional information transmission signal is allocated, The position of the carrier of the additional information transmission signal assigned to the segment for differential detection includes the position of the carrier of the additional information transmission signal assigned to the segment for coherent detection, The information transmission signal of the coherent detection segment absolute phase-modulates the respective assigned carriers according to the digital information, The information transmission signal of the segment for differential detection differentially modulates the respective assigned carriers based on the digital information, After Fourier transform is performed on the OFDM signal, coherent detection is performed on the segment for coherent detection, and differential detection is performed on the segment for differential detection, thereby restoring the digital information. 7. The receiving method according to claim 6, characterized in that, The absolute phase modulation is any one of QPSK modulation, 16QAM modulation, and 64QAM modulation. 8. The receiving method according to claim 6, characterized in that, The differential modulation is DQPSK modulation. 9. The receiving method according to claim 6, characterized in that, The additional information transmission signal differentially modulates the respective allocated carriers according to the additional information. 10. The receiving method according to claim 9, characterized in that, The differential modulation for the additional information transmission signal is DBPSK modulation. 11. A transmitting device for transmitting digital information as an OFDM signal, characterized in that, It includes: a carrier allocation device, which allocates the information transmission signal and the additional information transmission signal to a predetermined carrier; and an inverse Fourier transform means for generating the OFDM signal by performing an inverse Fourier transform on the output of the carrier configuration means, The OFDM signal includes 2 or more segments consisting of multiple carriers with continuous frequencies, The segment is either a segment for synchronous detection or a segment for differential detection, The coherent detection segment includes a carrier to which an additional information transmission signal is allocated and a carrier to which an information transmission signal is allocated, In the sector for coherent detection, the additional information transmission signal is allocated to a specific carrier, In the sector for coherent detection, the information transmission signal is allocated to any carrier other than the carrier to which the additional information transmission signal is allocated, The differential detection segment includes a carrier to which an additional information transmission signal is allocated and a carrier to which an information transmission signal is allocated, In the segment for differential detection, the additional information transmission signal is allocated to a specific carrier, In the segment for differential detection, the information transmission signal is allocated to any carrier other than the carrier to which the additional information transmission signal is allocated, The position of the carrier of the additional information transmission signal assigned to the segment for differential detection includes the position of the carrier of the additional information transmission signal assigned to the segment for coherent detection, The information transmission signal of the coherent detection segment absolute phase-modulates the respective assigned carriers based on the digital information, The information transmission signal of the segment for differential detection differentially modulates the carrier to which it is respectively assigned based on the digital information. 12. The sending device according to claim 11, wherein: The absolute phase modulation is any one of QPSK modulation, 16QAM modulation, and 64QAM modulation. 13. The sending device according to claim 11, characterized in that, The differential modulation is DQPSK modulation. 14. The sending device according to claim 11, characterized in that, The additional information transmission signal differentially modulates the respective allocated carriers according to the additional information. 15. The sending device according to claim 14, characterized in that, The differential modulation for the additional information transmission signal is DBPSK modulation. 16. A receiving device for receiving OFDM signals and restoring digital information, characterized in that, The OFDM signal includes 2 or more segments consisting of multiple carriers with continuous frequencies, The segment is either a segment for synchronous detection or a segment for differential detection, The coherent detection segment includes a carrier to which an additional information transmission signal is allocated and a carrier to which an information transmission signal is allocated, In the sector for coherent detection, the additional information transmission signal is allocated to a specific carrier, In the sector for coherent detection, the information transmission signal is allocated to any carrier other than the carrier to which the additional information transmission signal is allocated, The differential detection segment includes a carrier to which an additional information transmission signal is allocated and a carrier to which an information transmission signal is allocated, In the segment for differential detection, the additional information transmission signal is allocated to a specific carrier, In the segment for differential detection, the information transmission signal is allocated to any carrier other than the carrier to which the additional information transmission signal is allocated, The position of the carrier of the additional information transmission signal assigned to the segment for differential detection includes the position of the carrier of the additional information transmission signal assigned to the segment for coherent detection, The information transmission signal of the coherent detection segment absolute phase-modulates the respective assigned carriers according to the digital information, The information transmission signal of the segment for differential detection differentially modulates the respective assigned carriers based on the digital information, The receiving device includes: a Fourier transform device for performing Fourier transform on the OFDM signal, and The detection means performs coherent detection on the segment for coherent detection, and performs differential detection on the segment for differential detection in the output of the Fourier transform means. 17. The receiving device according to claim 16, characterized in that, The absolute phase modulation is any one of QPSK modulation, 16QAM modulation, and 64QAM modulation. 18. The receiving device according to claim 16, characterized in that, The differential modulation is DQPSK modulation. 19. The receiving device according to claim 16, characterized in that, The additional information transmission signal differentially modulates the respective allocated carriers according to the additional information. 20. The receiving device according to claim 19, wherein: The differential modulation for the additional information transmission signal is DBPSK modulation.

Images