Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L25/00—Baseband systems
  • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
  • H04L25/0202—Channel estimation
  • H04L25/0204—Channel estimation of multiple channels
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L25/00—Constructive types of pipe joints not provided for in groups F16L13/00 - F16L23/00 ; Details of pipe joints not otherwise provided for, e.g. electrically conducting or insulating means
  • F16L25/0036—Joints for corrugated pipes
  • F16L25/0045—Joints for corrugated pipes of the quick-acting type
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L19/00—Joints in which sealing surfaces are pressed together by means of a member, e.g. a swivel nut, screwed on or into one of the joint parts
  • F16L19/02—Pipe ends provided with collars or flanges, integral with the pipe or not, pressed together by a screwed member
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L27/00—Modulated-carrier systems
  • H04L27/26—Systems using multi-frequency codes
  • H04L27/2601—Multicarrier modulation systems
  • H04L27/2647—Arrangements specific to the receiver only

Definitions

• the present invention relates to an orthogonal frequency division multiplexing transmission system for transmitting signals suitable for fixed reception and mobile reception in one channel in a mixed manner. Further, the present invention relates to a transmitting apparatus for forming and transmitting an OFDM signal based on the orthogonal frequency division multiplexing method, and a receiving apparatus for receiving and demodulating an OFDM signal formed and transmitted based on the orthogonal frequency division multiplexing method.
• a transmitting apparatus for forming and transmitting an OFDM signal based on the orthogonal frequency division multiplexing method
• a receiving apparatus for receiving and demodulating an OFDM signal formed and transmitted based on the orthogonal frequency division multiplexing method.
• OFDM orthogonal frequency division multiplexing
• the entire transmission band is 17 k.
• 0 5 Carrier of carrier is used, of which 142 Carrier of carrier is used as dispersed pilot (Scattered Pilot) signal, and 45 carrier is used as continuous pilot. (Continual Pilot) signal, 17 carrier carrier is used for control information (TPS) signal, and 1512 carrier carrier is used for information transmission signal.
• TPS control information
• the continuous pilot signal of the carrier of 45 carriers is arranged so as to overlap with the distributed pilot.
• the frequency arrangement within one symbol is arranged in 12 carrier periods, and the frequency arrangement is shifted by 3 carriers for each symbol.
• the time arrangement has a period of 4 symbols.
• the distributed pilot signal is (1 ) Is assigned to the carrier with carrier number k.
• mod represents a modulo operation
• p is an integer from 0 to 141.
• the control information bit transmitted by the symbol of symbol number n is S n
• the control information signal is obtained by modulating the carrier with the complex vectors ck and n shown in equation (3). That is, the carrier that transmits the control information signal is differentially binary PSK (Phase Shift Keying) modulated between symbols.
• the carrier of the 1512 carrier used for information transmission signals other than the above can be QPSK, 16 QAM, or 6 4 QAM modulated. Both modulation methods are absolute phase modulation.
• FIG. 10 shows an example of a conventional receiving apparatus that receives the OFDM signal thus generated and demodulates digital information.
• a received OFDM signal is frequency-converted by a tuner 101, time-frequency-converted by a Fourier transform circuit 102, and is subjected to a frequency-domain carrier-to-frequency conversion. Kutl Column. This vector sequence is supplied to the distributed pilot extraction circuit 103 and the continuous pilot extraction circuit 109.
• the scattered pilot extracting circuit 103 extracts a scattered pilot signal from the vector sequence output from the Fourier transform circuit 102.
• the vector generation circuit 104 generates a modulation complex vector ck , n corresponding to the distributed pilot signal extracted by the distributed pilot extraction circuit 103.
• the division circuit 105 divides the distributed pilot signal extracted by the distributed pilot extraction circuit 103 by the complex vector generated by the vector generation circuit 104, From the result of the division, the transmission path characteristics of the distributed pilot signal are estimated.
• the interpolation circuit 106 interpolates the transmission line characteristics of the distributed pilot signal obtained by the division circuit 105 to estimate the transmission line characteristics of all the carrier waves.
• the divider circuit 107 performs synchronous detection by dividing the vector sequence output from the Fourier transform circuit 102 by the transmission path characteristics estimated by the interpolator 106 on the corresponding carrier.
• the demodulation circuit 108 demodulates the synchronous detection signal output from the division circuit 107 according to the modulation method (QPSK, 16 QAM, 64 QAM, etc.) when generating the information transmission signal, and transmits the demodulated signal. Obtained digital information.
• the continuous pilot extraction circuit 109 extracts a continuous pilot signal from the vector train output from the Fourier transform circuit 102.
• the vector generation circuit 110 generates the modulation complex vectors ck and n corresponding to the continuous pilot signals extracted by the continuous pilot extraction circuit 109.
• the division circuit 111 outputs the continuous pilot signal extracted by the continuous pilot extraction circuit 109. Divide by the complex vector generated by the vector generation circuit 110 to estimate the transmission path characteristics of the continuous pilot signal.
• the inverse Fourier transform circuit 112 converts the transmission path characteristic of the continuous pilot signal estimated by the division circuit 111 into frequency-to-hour conversion to obtain an impulse response characteristic of the transmission path. Disclosure of the invention
• a carrier for transmitting digital information is modulated by QPSK, 16 QAM, 64 QAM, etc., and the absolute phase modulation is performed. Since demodulation is based on the assumption that the transmission path characteristics estimated from the sparsely distributed distribution ports are smoothed and interpolated, the transmission path characteristics are used. Due to such factors, there are cases where sufficient transmission quality cannot be obtained with mobile reception in which the transmission path characteristics change rapidly.
• the modulation method of each carrier is determined to be one in the entire band, the digital information is transmitted so that some of the digital information can be received while moving. Even if, for example, differential QPSK modulation suitable for mobile reception is introduced into the modulation of the carrier transmitting the signal, the overall transmission capacity is reduced and the efficiency is reduced.
• the present invention solves the above-mentioned problems, and introduces a modulation method partially suitable for mobile reception for modulation of a carrier for transmitting digital information while maintaining the entire transmission capacity.
• An OFDM transmission system in which continuous pilot signals are arranged so that the impulse response of the transmission path estimated from the pilot signals does not return, and a transmitter and receiver suitable for this method The purpose is to provide equipment.
• an OFDM transmission system is configured as follows.
• a predetermined number of carriers are assigned as one unit to one or more segments, and one or more carriers are assigned to a band end pilot signal, A method in which one or more segments are used as either synchronous detection or differential detection for each segment, and
• a distributed pilot signal that modulates a carrier with a specific phase and amplitude is arranged on a carrier whose symbol time and frequency are periodically dispersed, and the same is applied to each symbol.
• M is a natural number of 2 or more
• phase shift keying M phase PSK
• differential M phase shift in the symbol direction according to the additional information.
• An additional information transmission signal to be modulated by keying is arranged, and an information transmission and transmission is performed on a carrier other than the above in accordance with the digital information. Issue an issue
• the M-phase shift keying or the differential M-phase phase in the symbol direction is applied to the carrier having the same frequency for each symbol according to the additional information.
• An additional information transmission signal to be modulated by shift keying is provided, and a carrier having a frequency that satisfies the periodicity of the frequency arrangement of the distributed pilot signal of the adjacent synchronous detection segment is provided.
• a terminal pilot signal for modulating the carrier at a specific phase and amplitude is arranged, and an information transmission signal for modulating the carrier according to the digital information is arranged for a carrier other than the above.
• the carrier is modulated with a specific phase and amplitude.
• a predetermined number of carriers are assigned as one unit to one or more segments, and one or more carriers are assigned to a band end pilot signal, A method in which one or more segments are used as either synchronous detection or differential detection for each segment, and
• a distributed pilot signal that modulates a carrier with a specific phase and amplitude is arranged on a carrier whose symbol time and frequency are periodically dispersed, and the same for each symbol.
• a continuous pilot signal that modulates the carrier with a specific phase and amplitude is arranged on the carrier of the same frequency, and the M-phase shift key is applied to the carrier of the same frequency for each symbol according to the additional information.
• An additional information transmission signal to be modulated by differential or M-phase shift keying in the symbol direction or in the symbol direction is arranged, and the carrier is applied to a carrier other than the above according to the digital information. Arrange the information transmission signal to be modulated,
• a continuous pilot signal that modulates the carrier with a specific phase and amplitude is arranged on a carrier having the same frequency as each symbol, and the same is applied to each symbol. Additional information that modulates the carrier by using the M-phase shift keying or the differential M-phase shift key in the symbol direction according to the additional information.
• a terminal pilot that distributes a transmission signal and modulates the carrier with a specific phase and amplitude on a carrier having a frequency that satisfies the periodicity of the frequency arrangement of the dispersion pilot port of the adjacent synchronous detection segment.
• the carrier is modulated with a specific phase and amplitude.
• the frequency arrangement of the additional information transmission signal is determined by changing the frequency arrangement of the additional information transmission signal in the differential detection segment. It is part of the frequency allocation.
• the frequency arrangement of the continuous pilot signal is changed by changing the frequency of the continuous pilot signal to the continuous pilot signal of the differential detection segment. It is part of the frequency allocation of.
• the additional information includes control information.
• control information is transmitted by differential two-phase shift keying (DBPSK) in the symbol direction.
• DBPSK differential two-phase shift keying
• a frequency allocation of the control information is a part of a frequency allocation of the control information of the differential detection segment. I do.
• the number of carriers is set to a multiple of N (N is a natural number of 2 or more), and the distributed pilot signal is set to L (L Is a divisor of N). Allocate to carriers shifted by carriers.
• each of the additional information transmission signals is The inverse Fourier transform pair in the frequency arrangement is arranged on a carrier wave with a frequency such that it becomes an impulse.
• each of the continuous pilot signals is converted into an inverse Fourier of the frequency arrangement of the continuous pilot signals.
• D) The transform pair is allocated to a carrier wave with a frequency that makes it impulse-shaped.
• the above-mentioned terminal pilot signal is arranged only on the carrier at the band end of the differential detection segment.
• the segment for synchronous detection is a distributed pilot signal using a carrier of 9 carriers per symbol, an additional information transmission signal using a carrier of 3 carriers, and 9 And an information transmission signal using a 6-carrier carrier.
• the differential detection segment comprises: an additional information signal using a 11-carrier carrier; a termination packet signal using a 1-carrier carrier; and a 96-carrier carrier. And an information transmission signal using the same.
• the synchronous detection segment includes a distributed pilot signal using 9 carriers per symbol, and an additional information transmission signal using 1 carrier. It consists of a continuous pilot signal using two carrier waves and an information transmission signal using 96 carrier waves.
• the differential detection segment comprises an additional information signal using a 5-carrier carrier, a continuous pilot signal using a 6-carrier carrier, and a 1-carrier carrier.
• the terminal pilot signal used is composed of an information transmission signal using a 96-carrier carrier.
• a predetermined number of carriers are assigned as one unit to one or more segments, and one or more carriers are assigned to a band end pilot signal, and the one An array means for allocating the above segments to either synchronous detection or differential detection for each segment,
• Signal generating means for generating the distributed pilot signal, the additional information transmission signal, the information transmission signal, the terminal pilot signal, and the band terminal pilot signal, respectively.
• the band-end pilot signal is transmitted at a frequency satisfying the periodicity of the frequency arrangement of the distributed pilot signal in the synchronous detection segment and at the end of a transmission frequency band.
• the distributed pilot signal is distributed to a carrier wave whose symbol time and frequency are periodically dispersed, and the additional information transmission signal is also transmitted to each symbol.
• the information transmission signal is arranged on a carrier having the same frequency
• the information transmission signal is arranged on a carrier other than the above
• the additional information transmission signal is arranged on a carrier having the same frequency as each symbol.
• the terminal pilot signal satisfies the periodicity of the frequency arrangement of the distributed pilot signal in the adjacent synchronous detection segment. It is arranged on the carrier wave of the frequency.
• a predetermined number of carriers are assigned as one unit to one or more segments, and one or more carriers are assigned to a band end pilot signal, and the one An array means for allocating the above segments to either synchronous detection or differential detection for each segment,
• the band-end pilot signal is transmitted at a frequency satisfying the periodicity of the frequency arrangement of the distributed pilot signal in the synchronous detection segment and at a transmission frequency band end.
• the dispersed pilot signal is disposed on a carrier wave whose periodicity and frequency are periodically dispersed, and the continuous pilot signal is transmitted every symbol.
• the additional information transmission signal is arranged on a carrier having the same frequency as each symbol, and the information transmission signal is arranged on a carrier other than the above, and the differential detection cell is arranged.
• the continuous pilot signal is arranged on a carrier having the same frequency as each symbol, and the additional information transmission signal is arranged on a carrier having the same frequency as each symbol.
• Frequency pie Lock preparative signal the dispersion pi port Tsu DOO signal synchronous detection segmenting preparative you adjacent It is arranged on the carrier wave of the frequency that satisfies the periodicity of arrangement. Further, the receiving device according to the present invention is configured as follows.
• (23) A receiving device that receives and demodulates the OFDM signal generated by the OFDM transmission method according to any one of (1) to (18).
• Fourier transform means for converting the received OFDM signal from a time domain to a frequency domain signal by Fourier transform to obtain a vector sequence representing a phase and an amplitude for each of the carrier waves;
• the vector group extracted by this means is divided by the specific phase and amplitude modulating the dispersion pilot signal, the terminal pilot signal, and the band terminal pilot signal.
• Filter means for smoothing and interpolating the output of this means in the frequency direction and symbol time direction;
• Delay means for delaying the vector sequence obtained by the Fourier transform means for one symbol period
• the The output of the filter means should be output from the selection means for selecting and outputting the output of the delay means when processing the signal of the differential detection segment, and the output from the Fourier conversion means.
• Second division means for dividing the vector sequence by the output signal of the selection means to obtain and output a detection vector sequence.
• Fourier transform means for converting the received OFDM signal from a time domain to a frequency domain signal by Fourier transform to obtain a vector sequence representing the phase and amplitude of each carrier.
• Third division means for dividing the vector group extracted by this means by the specific phase and amplitude modulating the continuous pilot signal
• An inverse Fourier transforming means for converting the output of this means from the frequency domain to the time domain by means of the inverse Fourier transform, thereby obtaining an impulse response characteristic of the transmission line.
• FIG. 1 shows the first and second embodiments of the OFDM transmission system according to the present invention, in which synchronous detection or differential detection segments (a total of 13 segments) and a band termination pyrometer are shown.
• FIG. 4 is a diagram showing an example of arrangement.
• FIG. 2 shows the arrangement of the additional information transmission signal, the arrangement of the distributed pilot signal in the synchronous detection segment, and the differential detection in the first and second embodiments of the OFDM transmission system according to the present invention.
• FIG. 10 is a diagram showing an example of an arrangement of a terminal pilot signal in a segment for use.
• FIG. 3 shows an arrangement of a continuous pilot signal and a control information signal and an arrangement of a distributed pilot signal in a synchronous detection segment in a second embodiment of the OFDM transmission system according to the present invention.
• FIG. 4 is a diagram showing an example of the arrangement of a terminal pilot signal in a differential detection segment.
• FIG. 4 is a time chart showing an inverse Fourier transform pair of the frequency arrangement of the continuous pilot signal of the synchronous detection segment shown in Table 2 in the second embodiment of the OFDM transmission system according to the present invention.
• FIG. 4 is a diagram showing one amplitude characteristic.
• FIG. 5 shows an inverse Fourier transform pair of the frequency arrangement of the continuous pilot signal of the differential detection segment shown in Table 2 in the second embodiment of the OFDM transmission system according to the present invention.
• FIG. 4 is a time-amplitude characteristic diagram shown.
• FIG. 6 is a time-amplitude diagram illustrating an inverse Fourier transform pair of the frequency arrangement of the control information signal of the synchronous detection segment shown in Table 3 in the second embodiment of the OFDM transmission system according to the present invention.
• FIG. 6 is a time-amplitude diagram illustrating an inverse Fourier transform pair of the frequency arrangement of the control information signal of the synchronous detection segment shown in Table 3 in the second embodiment of the OFDM transmission system according to the present invention.
• FIG. 7 is a time chart showing the inverse Fourier transform pair of the frequency arrangement of the control information signal of the segment for differential detection shown in Table 3 in the second embodiment of the OFDM transmission system according to the present invention. Amplitude characteristics diagram It is.
• FIG. 8 is a block diagram illustrating a configuration of a transmission device used in an OFDM transmission system according to a fifth embodiment of the present invention, as a fifth embodiment.
• FIG. 9 is a block circuit diagram showing, as a sixth embodiment, the configuration of a receiving device used in the OFDM transmission system according to the present invention.
• FIG. 10 is a block diagram showing a configuration of a receiving apparatus used in the conventional OFDM transmission system.
• a band termination pilot using 13 segments and one carrier is used, and one segment has 108 carriers. It is composed of the carrier wave of (a). Each segment consists of a segment for synchronous detection or a segment for differential detection. A carrier of 1405 carriers is used for the entire band.
• Figure 1 shows examples of segments for synchronous detection or differential detection (total of 13 segments), and band-terminated pilot signals.
• the horizontal axis schematically represents the frequency axis (carrier arrangement), and the vertical axis represents the time axis (symbol direction).
• the carrier number k of, is an integer from 0 to 107, and one segment consists of 108 carrier waves.
• the segments for synchronous detection are a distributed pilot signal using nine carriers per symbol, an additional information transmission signal using three carriers, and a 96-carrier carrier. And an information transmission signal using the carrier of the lear.
• the differential detection segment includes an additional information transmission signal using a 11-carrier carrier, a termination pilot signal using a 1-carrier carrier, and a 96-carrier carrier. It consists of an information transmission signal using a carrier wave and a signal.
• the required transmission band depends on the combination of the segments. It will not change.
• the carrier number k in the entire band is 0, an integer of 1404, the segment number i is 0, an integer of 1 to 12, and the carrier in each segment.
• the rear number k 'be an integer from 0 to 107, and satisfy k i ⁇ 108 + k'.
• the distributed pilot signal provided in the segment for synchronous detection is allocated to the carrier of carrier number k in the segment by equation (5) with each segment.
• mod represents the remainder operation
• n indicating the symbol number is an integer of 0 or more
• p is an integer of 0 or more and 8 or less.
• the additional information transmission signals provided in the segment for synchronization and the segment for differential detection are as shown in Table 1. It is located on the carrier with carrier number k '. Table 1 shows that the additional information transmission signal of the synchronous detection segment is included in the additional information transmission signal of the differential detection segment.
• the synchronous detection segment and the differential detection segment are defined as additional information transmission signals of the synchronous detection segment. Since the additional information transmission signal is always arranged on the carrier wave, it is easy for the receiving side to identify the additional information transmission signal or the other transmission signal. Note that, depending on the additional information to be transmitted, the carrier wave may be assigned so that the subset arrangement does not occur.
• the terminal pilot signal provided in the segment for differential detection is allocated to a carrier having a carrier number k 'of 0 in each segment.
• the arrangement of the terminal pilot signal is a position that maintains the periodicity of the frequency arrangement of the distributed pilot signal in the adjacent synchronous detection segment.
• Each terminal pilot signal complements the distributed pilot signal.
• Figure 2 shows an example of the arrangement of the distributed pilot signal in the segment for synchronous detection and the example of the arrangement of the terminal pilot signal in the segment for differential detection.
• the horizontal axis schematically represents the frequency axis (carrier arrangement), and the vertical axis the time axis (symbol direction).
• the carrier number k 'in each segment is an integer from 0 to 107, and one segment is composed of 108 carrier waves.
• the additional information transmission signal is assigned to a different carrier from the dispersion pilot signal.
• Equation (6) R e ⁇ c kn ⁇ represents the real part of the complex vector ck, n corresponding to the carrier of carrier number k and symbol number n, and I m ⁇ c k; n ⁇ Represents an imaginary part.
• the additional information transmission signal provided in the synchronous detection segment and the differential detection segment transmits additional information different from the information transmission signal transmitted using a 96-carrier carrier.
• control information that specifies the transmission mode (number of segments, carrier modulation method, etc.), information used as a broadcast station (eg, control information used in a relay station, Low-time-delayed audio information used for communication, broadcast station identification signal, etc.) can be considered.
• One bit of additional information may be transmitted for each symbol, or multiple bits of additional information may be transmitted. Alternatively, only control information that defines the transmission mode may be transmitted.
• the control information signal modulates the carrier by the complex vector c k, n shown in equation (7).
• the carrier for transmitting the control information signal is differentially binary-shifted PSK (Phase Shift Keying) modulated between the symbols.
• the information transmission signal provided in the synchronous detection segment is distributed to a carrier other than the dispersion pilot signal and the additional information transmission signal of the aforementioned synchronous detection segment, and is discontinued based on the digital information.
• Phase modulation is performed.
• QPSK for example, QPSK :, 16QAM, or 64QAM modulation is used.
• the information transmission signal of the synchronous detection segment is demodulated by the following process.
• the distributed pilot signal, the required terminal pilot signal, and the band terminal pilot signal are modulated by the dispersion pilot, terminal pilot signal, and band terminal pilot signal. It performs inverse modulation with the complex vector, and estimates the transmission path characteristics in the frequency domain related to the scattered pilot signal and the terminal pilot signal. Further, the transmission path characteristics of the information transmission signal are estimated by interpolating in the frequency direction and the symbol direction by a filter. The information transmission signal is divided by the transmission path characteristics obtained in this way. As a result, the information transmission signal can be demodulated from the synchronous detection segment.
• the information transmission signal provided in the differential detection segment is described above. Differential modulation between adjacent symbols of the same carrier number, based on digital information, is allocated to the carrier signal other than the pilot signal at the end of the differential detection segment and the additional information transmission signal. Is applied.
• the information transmission signal of the differential detection segment can be demodulated by dividing by the information transmission signal of the same carrier number of the previous symbol.
• the OFDM transmission method provides high-quality reception by the effect of the filter in the synchronous detection segment in the receiving apparatus and the differential detection for the differential detection.
• differential demodulation between symbols makes it possible to perform reception suitable for mobile reception in which the transmission path characteristics change rapidly.
• a flexible service configuration without fluctuations in the transmission band can be achieved. It can be realized.
• a band termination pilot using 13 segments and one carrier is used, and one segment is 10 8 It consists of the carrier of the carrier.
• Each segment is composed of either a segment for synchronous detection or a segment for differential detection.
• a carrier of 1405 carriers is used for the entire band.
• the synchronous detection segment consists of a distributed pilot signal using nine carriers per symbol and a two-carrier carrier.
• a pilot signal using a carrier an additional information transmission signal using a carrier of one carrier (hereinafter, referred to as a control information signal in this embodiment), and an information transmission signal using a carrier of 96 carriers. It consists of a transmission signal.
• the differential detection segment is composed of a continuous pilot signal using a 6-carrier carrier, a control information signal using a 5-carrier carrier, and a 1-carrier carrier. It consists of the terminal pilot signal used and an information transmission signal using a 96-carrier carrier.
• the carrier number k for the entire band is an integer from 0 to 144
• the segment number i is an integer from 0 to 12
• the distributed pilot signal provided in the segment for synchronous detection is placed on the carrier of the carrier number k 'in the segment according to equation (5), together with each segment.
• mod represents the remainder operation
• p is an integer from 0 to 8 inclusive.
• the continuous pilot signals provided for the segment for synchronization and the segment for differential detection are within the respective segments shown in Table 2. Is placed on the carrier with carrier number k '. Table 2 shows that the continuous pilot signal of the segment for synchronous detection is included in the continuous pilot signal of the segment for differential detection. Table 2 Frequency arrangement of continuous pilot signal
• a continuous pilot signal is always arranged on the carrier wave, so that it is easy for the receiving side to distinguish between a continuous pilot signal and other transmission signals.
• carriers may be assigned so as not to be in a partial arrangement.
• a continuous pilot signal that modulates the carrier with a specific phase and amplitude on a carrier with the same frequency for each symbol is a carrier used as a reference on the receiving side because the frequency, phase, and amplitude are specified. You can use it.
• the terminating pilot signal provided in the differential detection segment is arranged on a carrier having a carrier number k 'of 0 in each segment.
• the arrangement of the terminal pilot signal is a position that maintains the periodicity of the frequency arrangement of the distributed pilot signal in the adjacent synchronous detection segment.
• Each terminal pilot signal complements the distributed pilot signal.
• Figure 3 shows the arrangement of the continuous pilot signal and the control information signal, the arrangement of the distributed pilot signal in the segment for synchronous detection, and the termination pilot signal in the segment for differential detection.
• the horizontal axis schematically represents the frequency axis (carrier arrangement), and the vertical axis represents the time axis (symbol direction).
• the carrier number k 'in each segment is set to 0 and the integer of 107 is set, and one segment is composed of 108 carrier waves.
• the continuous pilot signal and the control information signal are assigned to a different carrier from the dispersed pilot signal. These distributed pilot signals, continuous pilot signals, and terminal pilot signals are respectively assigned carrier numbers k.
• Equation (6) R e ⁇ c k , n ⁇ represents the real part of the complex vector c kn corresponding to the carrier of carrier number k and symbol number n, and I m ⁇ ckn ⁇ represents the imaginary part.
• control information signals provided for the synchronous detection segment and the differential detection segment are respectively the control information signals in each segment shown in Table 3. It is arranged on the carrier with the rear number k 'and transmits 1-bit control information for each symbol.
• control information bits to be transmitted in symbol of the symbol number n When S n, the control information signal is obtained by modulating a carrier wave by Tsu by the (7) complex base-vector c k in the expression, n. That is, the carrier that transmits the control information signal is differentially binary PSK (Phase Shift Keying) modulated between symbols.
• PSK Phase Shift Keying
• the carrier for transmitting the control information is based on the above-mentioned PN sequence w k and the complex vector c k , Modulated by n .
• Inverse modulation is performed using the complex vector, and the channel characteristics in the frequency domain related to the scattered pilot signal and the terminal pilot signal are estimated. Further, a filter is used to interpolate in the frequency direction and the symbol direction to estimate the transmission path characteristics of the information transmission signal.
• the information transmission signal is divided by the transmission path characteristics obtained in this way. As a result, the information transmission signal can be demodulated from the synchronous detection segment.
• the information transmission signal provided in the differential detection segment is distributed to the carrier signal other than the continuous pilot signal, the terminal pilot signal, and the control information signal of the differential detection segment described above. Then, based on the digital information, differential modulation is performed between adjacent symbols having the same carrier number.
• differential modulation for example, DBPSK :, DQPSK, DAPSK, etc. are used.
• the information transmission signal of the differential detection segment can be demodulated by being divided by the information transmission signal of the same carrier number as the previous symbol.
• the OFDM transmission method provides high-quality reception by the effect of the filter in the synchronous detection segment and the differential detection segment in the receiving apparatus.
• differential demodulation between symbols it is possible to perform reception suitable for mobile reception in which the transmission path characteristics change rapidly.
• a flexible service configuration can be realized by arbitrarily combining the segment for synchronous detection and the segment for differential detection.
• the frequency, phase, and amplitude are specified. This can be used as a reference carrier on the side.
• Figures 4 and 5 show the synchronous detection segment (13 segment, 26 carrier) and differential detection segment (13 segment, 26 segment) shown in Table 2, respectively.
• This figure shows an inverse Fourier transform pair of the frequency arrangement of a continuous pilot signal of 78 carriers). From FIGS. 4 and 5, it can be said that they are impulse-like and that the frequency arrangement of the continuous pilot signal shown in Table 2 has no periodicity.
• the OFDM transmission method of the present embodiment can prevent the entire continuous pilot signal from disappearing due to a delay wave such as a multipath.
• a delay wave such as a multipath.
• the impulse response of the transmission path can be obtained. Note that the frequency allocation of the continuous pilot signal is strong against autocorrelation.
• the OFDM transmission scheme according to the present embodiment can prevent the entire control information signal from disappearing due to a delay wave such as a multipath.
• the frequency allocation of the additional information transmission signal including the control information signal can be set in the same manner.
• FIG. 8 shows a configuration of an embodiment of a transmitting apparatus that generates an OFDM signal based on the OFDM transmission schemes of the first and second embodiments.
• the information transmission signal generation circuit 51 performs error control processing (error correction coding, interleaving, energy diffusion, etc.) and digitization as necessary for the input digital information. Apply digital modulation.
• error control processing error correction coding, interleaving, energy diffusion, etc.
• digitization as necessary for the input digital information.
• Apply digital modulation digital modulation.
• the basic error control processing method and digital modulation method generally used in digital transmission are omitted because they are well-known technologies.
• absolute phase modulation is performed as digital modulation.
• absolute phase modulation for example, QPSK, 16QAM, 64QAM modulation, or the like is used.
• differential modulation is performed between adjacent symbols having the same carrier number based on digital information.
• DBPSK DQPS :, DAPSK, and the like are used.
• the additional information signal generating circuit 52 performs error control processing (error correction coding, interleaving, energy spreading, etc.) and digital modulation on the input additional information as necessary.
• error control processing error correction coding, interleaving, energy spreading, etc.
• digital modulation M (M is a natural number of 2 or more) phase PSK (Phase Shift Keying) modulation or differential M-phase PSK modulation in the symbol direction is used.
• the control information generation circuit 56 transmits the transmission mode information (the number of segments for synchronous detection, the number of segments for differential detection, the carrier modulation method, etc.) required on the receiving side. (Specified information). This information is subjected to error control processing and digital modulation in the additional information signal generation circuit 52. However, even if error control processing and digital modulation different from other additional information are performed, Good.
• the termination pilot signal generation circuit 54 is provided with a carrier number k (segment number i and carrier number k in each segment) whose arrangement is defined by the carrier arrangement circuit 57.
• the additional information signal generation circuit 52 modulates the carrier with the same phase and amplitude for each symbol for each carrier.
• the carrier arrangement circuit 57 the information transmission signal generation circuit 51, the additional information signal generation circuit 52, the distributed pilot signal generation circuit 53, the termination pilot signal generation circuit 54, and the band termination
• Each output (complex vector train) of the lot signal generation circuit 55 is arranged at a carrier position in the frequency domain defined according to the transmission mode.
• the output of the distributed pilot signal generation circuit 53 is N (where N is a natural number of 2 or more) within the synchronous detection segment at carrier intervals and L (L is a divisor of N) for each symbol.
• the output of the additional information signal generation circuit 52 is assigned according to, for example, the frequency arrangement shown in Table 1.
• the vector train for each carrier in the base frequency band arranged in this way is input to the inverse free transform circuit 58.
• the inverse Fourier transform circuit 58 converts the vector train for each carrier in the base frequency band generated by the carrier arranging circuit 57 from the frequency domain to the time domain, and uses a commonly used guardian. Output with an interpal period added.
• a quadrature modulation circuit 59 performs quadrature modulation on the output of the inverse Fourier conversion circuit 58 and converts it to an intermediate frequency band.
• the frequency conversion circuit 60 converts the frequency band of the orthogonally modulated OFDM signal from an intermediate frequency band to a radio frequency band, and supplies it to an antenna or the like.
• an OFDM signal based on the OFDM transmission scheme described in the first and second embodiments is generated. Can be achieved.
• FIG. 9 shows a receiving apparatus capable of receiving an OFDM signal formed based on the OFDM transmission schemes of the first and second embodiments and estimating an impulse response in a time domain of a transmission path. The configuration of is shown.
• tuner 11 converts the frequency band of the received OFDM signal from a radio frequency band to a base frequency band.
• the Fourier transform circuit 12 converts the OFDM signal in the base frequency band from the time domain to the frequency domain, and outputs it as a vector train for each carrier in the frequency domain.
• the distributed Z-terminated pilot extraction circuit 13 outputs a distributed pilot signal, a necessary terminal pilot signal, and a band terminal pilot signal from the vector train output from the Fourier transform circuit 12. Extract the signal.
• the vector generation circuit 14 is a modulation complex corresponding to the dispersed pilot signal, the terminated pilot signal, and the band terminated pilot signal extracted by the distributed Z-terminated pilot extracting circuit 13. Generates the vector c n .
• the division circuit 15 converts the distributed pilot signal, the terminal pilot signal and the band terminal pilot signal extracted by the distributed terminal pilot extraction circuit 13 into a vector generation circuit 1. Divide by the complex vector in which 4 occurs to estimate the transmission path characteristics of the distributed pilot signal, the terminal pilot signal, and the band terminal pilot signal.
• the interpolation circuit 16 applies the dispersion pilot signal, the termination pilot signal, and the band termination pilot signal obtained in the division circuit 15 to each other. By interpolating the transmission path characteristics, the transmission path characteristics of the carrier of the information transmission signal of the synchronous detection segment are estimated.
• the delay circuit 17 delays the vector sequence output from the Fourier transform circuit 12 by one symbol.
• the selection circuit 18 outputs the output of the interpolation circuit 16 in the case of the segment for synchronous detection and the segment for differential detection in accordance with the type of the segment separately transmitted by the control information. In this case, the output of the delay circuit 17 is selected and output.
• the division circuit 19 divides the vector sequence output from the Fourier transform circuit 12 by the output of the selection circuit 18.
• the signal is divided by the transmission path characteristic of the corresponding carrier estimated in the interpolation circuit 16 to perform synchronous detection, and in the differential detection segment, the delay circuit is used. Divide by the vector row of the corresponding carrier one symbol before 1 output by 17 to perform differential detection.
• the demodulation circuit 20 is output from the division circuit 19 according to the modulation method (QPSK :, 16 QAM, 64 QAM, DBPSK :, DQPSK :, DAPSK, etc.) when generating the information transmission signal. Demodulated the detected signal to obtain the transmitted digital information.
• the modulation method QPSK :, 16 QAM, 64 QAM, DBPSK :, DQPSK :, DAPSK, etc.
• the continuous pilot extraction circuit 21 extracts a continuous pilot signal from the vector sequence output from the Fourier transform circuit 12. You. At this time, even if the synchronous detection segment and the differential detection segment are mixed, at least the continuous pilot signal of the synchronous detection segment must be mixed. Therefore, a continuous pilot signal can always be extracted.
• the vector generation circuit 22 generates a modulation complex vector ck , n corresponding to the continuous pilot signal extracted by the continuous pilot extraction circuit 21.
• the division circuit 23 divides the continuous pilot signal extracted by the continuous pilot extraction circuit 21 by a complex vector generated by the vector generation circuit 22 to obtain a continuous pilot signal. Estimate the transmission path characteristics of the lot signal.
• the inverse Fourier transform circuit 24 converts the transmission path characteristic of the continuous pilot signal estimated by the division circuit 23 from the frequency domain to the time domain to obtain an impulse response characteristic of the transmission path. .
• the filter effect by the interpolation processing of the transmission path characteristic is used.
• the inverse Fourier transform circuit 24 it is possible to obtain an impulse response characteristic of the transmission line without turning back.
• the orthogonal frequency division multiplexing transmission system of the present invention may include a differential detection segment suitable for mobile reception. it can.
• the segment detection characteristics of adjacent segments for synchronous detection are not impaired.
• the segment for synchronous detection and the segment for differential detection can be freely combined for each point, thereby realizing a flexible service form.
• the impulse response characteristics of a transmission line that does not return in the symbol period are obtained as necessary using a continuous pilot signal in which the inverse Fourier transform pair of the frequency arrangement is impulse-like. You can do it.
• a modulation scheme suitable for mobile reception is partially introduced into the modulation of a carrier wave for transmitting digital information while maintaining the overall transmission capacity.
• An OFDM transmission system in which continuous pilot signals are arranged so that no aliasing occurs in the impulse response of the transmission path estimated from the lot signal, and a transmitter and receiver suitable for this system Can be provided.

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