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WO2007015317A1 - Transmetteur, récepteur, procédé de communication et système de transmission/réception - Google Patents

Transmetteur, récepteur, procédé de communication et système de transmission/réception Download PDF

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Publication number
WO2007015317A1
WO2007015317A1 PCT/JP2006/303073 JP2006303073W WO2007015317A1 WO 2007015317 A1 WO2007015317 A1 WO 2007015317A1 JP 2006303073 W JP2006303073 W JP 2006303073W WO 2007015317 A1 WO2007015317 A1 WO 2007015317A1
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WO
WIPO (PCT)
Prior art keywords
signal
filter
transmitter
receiver
transmission
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2006/303073
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English (en)
Japanese (ja)
Inventor
Hideaki Sakai
Kazunori Hayashi
Yoji Okada
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sumitomo Electric Industries Ltd
Kyoto University NUC
Original Assignee
Sumitomo Electric Industries Ltd
Kyoto University NUC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sumitomo Electric Industries Ltd, Kyoto University NUC filed Critical Sumitomo Electric Industries Ltd
Priority to JP2007529180A priority Critical patent/JPWO2007015317A1/ja
Publication of WO2007015317A1 publication Critical patent/WO2007015317A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/12—Frequency diversity
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/0001—Systems modifying transmission characteristics according to link quality, e.g. power backoff
    • H04L1/0002—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate
    • H04L1/0003—Systems modifying transmission characteristics according to link quality, e.g. power backoff by adapting the transmission rate by switching between different modulation schemes

Definitions

  • the present invention relates to a frequency diversity transmitter, a receiver, a communication method, and a transmission / reception system.
  • the diversity method is a technique for reducing random fluctuation of a signal passing through a propagation path. If the reception level of one or more of the two or more received waves drops, but the other does not drop, select either of the two received waves or synthesize the two received waves to achieve high-quality transmission. Can be realized.
  • branches In order to obtain a plurality of fading waves (referred to as branches) that vary independently from each other, there is a method of using space, polarization, angle, frequency, or time.
  • frequency diversity using a frequency as a branch is a communication method in which modulation is performed using a plurality of carrier waves having different frequencies on the transmission side.
  • the receiving side selects or combines the multiple fading waves obtained.
  • a transceiver corresponding to the number of normal branches is required. For example, if there are two branches, two transceivers are required.
  • On the receiving side it is necessary to prepare a filter for separating the frequency band for each branch, and it is necessary to provide a guard band in accordance with the steepness of the filter.
  • Non-Patent Document 1 block transmission schemes using cyclic prefix (also referred to as CP or guard interval) (See Non-Patent Document 1).
  • CP cyclic prefix
  • the block transmission system using CP is a system that performs block transmission by copying one or more signals at the end of the transmission signal block to the beginning or the end.
  • the equalizer weight can be represented by a diagonal matrix ⁇ .
  • the diagonal component of the diagonal matrix ⁇ is represented by ⁇ 1, ..., ⁇ ⁇ .
  • ⁇ ⁇ represents the number of discrete frequencies when the discrete Fourier transform is performed, that is, the FFT size.
  • ZF equalizer weight As a type of conventional equalizer weight, for example, there is a weight based on zero forcing (ZF). ZF equalizer weight is
  • ⁇ ⁇ is a frequency transfer function of the transmission line.
  • Non-Patent Document 2 a fractional interval equalization method that improves the equalization performance by oversampling at the reception side has been proposed (see Non-Patent Document 2). According to this method, receiver performance that is more resistant to intersymbol interference than before can be achieved by using equalizer weights with higher frequency components for received signals that are oversampled at a density twice the symbol rate. Can be obtained.
  • Non-Special Reference 1 Kazunori Hayashi "Fundamentals of Modulation / Demodulation and Equation Technologies” Proc. MWE2004, pp.523— 532, 2004
  • Non-Patent Document 2 P. P. Vaidyanathan and B. Vrcelj, "Theory of fractionally spaced cycli c— prefix equalizer,” Proc. ICASSP, vol.2, pp.1277—1280, 2002.
  • the present invention provides a transmitter, a receiver, a communication method, and a transmission / reception system that can obtain stable communication quality by frequency diversity and the effect of reducing intersymbol interference even in a poor transmission environment with a simple configuration. The purpose is to provide.
  • the transmitter of the present invention includes a k 1 between a baseband modulator that generates a complex baseband signal based on a digital signal to be transmitted and temporally adjacent data of the complex baseband signal.
  • a band limiting filter selected from a root Nyquist filter with a Nyquist bandwidth of kR or more, a Gaussian filter with a 3 dB bandwidth of kR or more, or an approximate filter close to the characteristics of those filters.
  • a frequency diversity signal having k branches is generated by orthogonally modulating the complex signal that has passed through the band limiting filter.
  • the zero insertion switch inserts (k 1) copies of the frequency spectrum of the complex baseband signal before zero insertion on the frequency axis, and inserts the occupied bandwidth of the transmission signal to zero. This is to increase the previous k (k ⁇ 1) times. Even when the transmitter reduces the time interval of the complex baseband signal to lZk, a copy of the frequency spectrum of the signal before insertion is kept within the occupied band while keeping the occupied bandwidth of the transmitted signal constant (k 1) You can place yourself next to each other.
  • the signal after passing through the zero insertion switch has an infinite bandwidth, it is preferable to remove unnecessary frequency components by the band limiting filter.
  • Inter-symbol interference will occur if only band limiting is performed. Use a band limiting filter that satisfies the conditions during reception to reduce the adverse effects of inter-symbol interference.
  • a frequency diversity signal with k branches can be obtained with a simple configuration as compared with the conventional variable symbol rate adaptive modulation system.
  • the number of transceivers required is equal to the number of branches, but in this configuration, only one is necessary.
  • a conventional frequency diversity transmitter requires a guard band for separating each branch signal with a filter.
  • transmission with high frequency utilization efficiency that is not necessary is possible.
  • the transmitter of the present invention includes a CP-attached circuit that blocks the digital signal every N samples and adds a cyclic prefix!
  • the transmitter of the present invention may further include a frequency domain equalization unit that performs fractionally spaced equalization (Fractionally Spaced Equalizer) using the estimated transfer path transfer function.
  • Fractionally Spaced Equalizer fractionally Spaced Equalizer
  • the frequency domain equalization section is preferably arranged after the zero inserter and before the CP-added caro circuit.
  • the FSE function is on the receiving side, but by moving this function to the transmitting side, the signal processing load on the receiver can be reduced.
  • a receiver of the present invention is a receiver for receiving the frequency diversity signal having the number of branches k, and an orthogonal demodulator that develops the received signal in a complex plane; Root Nyquist filter with a Nyquist bandwidth, Gaussian filter with a 3 dB bandwidth greater than or equal to kR, or a band-limiting filter in which the intermediate force of those approximate filters is also selected and complex signal power It is equipped with a baseband demodulator that restores digital signals.
  • the receiver of the present invention has a sample necessary for signal determination from all received samples at any position between the quadrature demodulator and the baseband demodulator. You may even have a bow filter while extracting.
  • the receiver of the present invention may further include a CP removing circuit that removes a cyclic prefix in correspondence with the transmitter.
  • the receiver of the present invention may further include a frequency domain equalization unit that performs frequency domain equalization using the estimated transfer path transfer function. According to this configuration, when a signal is transmitted without performing fractional interval equalization on the transmitter side, the signal can be received and equalization can be performed on the receiver side. As a result, equalization for intersymbol interference caused by multiwave propagation can be performed simultaneously.
  • the communication method of the present invention defines a transmission procedure by the transmitter and a reception procedure by the receiver as a series of procedures.
  • the transmission / reception system of the present invention includes the transmitter and the receiver, and the receiver evaluates a transmission quality of a signal on a transmission path from the transmitter to the receiver. And a transmission control unit that transmits the evaluation result to the transmitter, and the transmitter transmits the communication speed while reducing the communication speed based on the evaluation result of the transmission quality evaluation unit transmitted from the receiver. It can be controlled to keep the occupied bandwidth of the signal constant and increase the number of diversity branches.
  • FIG. 1 is a block diagram of a frequency diversity transmitter of the present invention in a single carrier block transmission system.
  • FIG. 2 is a block diagram of a frequency diversity receiver that is paired with the frequency diversity transmitter.
  • FIG. 3 is a block diagram for explaining fractional interval equalization processing.
  • FIG. 4 is a diagram for explaining each signal waveform of the receiver.
  • FIG. 5 is a block diagram of a frequency diversity transmitter of the present invention that performs fractional interval equalization processing on the transmitter side.
  • FIG. 6 is a block diagram of a frequency diversity receiver paired with the frequency diversity transmitter.
  • FIG. 7 is a block diagram for explaining fractional interval equalization processing.
  • FIG. 8 is a diagram for explaining signal waveforms of a transmitter when oversampling is performed twice.
  • FIG. 9 (a) is a diagram showing a signal waveform at the output point (1) of the baseband modulator 2 in FIG. 1, and FIG. 9 (b) is a diagram showing a frequency spectrum of the signal.
  • FIG. 10 (a) is a diagram showing a signal waveform that has passed through the zero insertion switch 3
  • FIG. 10 (b) is a diagram showing a frequency spectrum.
  • FIG. 11 (a) is a diagram showing a signal waveform after passing through the band limiting filter 6, and FIG. 11 (b) is a diagram showing a frequency spectrum.
  • FIG. 12 (a) is a diagram showing a signal waveform after passing through the band limiting filter 14 in the receiver
  • FIG. 12 (b) is a diagram showing a frequency spectrum.
  • FIG. 13 (a) is a diagram showing a signal waveform after passing through the interleaved filter in the receiver
  • FIG. 13 (b) is a diagram showing a frequency spectrum.
  • FIG. 14 is a block diagram of a frequency diversity receiver.
  • FIG. 15 is a flowchart showing a procedure for transmitting transmission quality information from a receiver to a transmitter.
  • FIG. 16 is a flowchart showing a procedure for changing a setting in a transmitter receiving transmission quality information.
  • FIG. 17 is a map showing an example of changing a modulation scheme and a symbol rate according to a BER value.
  • FIG. 18 is a block diagram showing a modification of the frequency diversity transmitter of the present invention that performs fractional interval equalization processing on the transmitter side.
  • FIG. 1 shows a single carrier block transmission (hereinafter referred to as single carrier block transmission).
  • FIG. 2 is a block diagram of a frequency diversity transmitter of the present invention adopting SCBT method and i).
  • This transmitter includes a baseband modulator (Mapper) 2 that maps a digital signal to be transmitted onto a complex plane, and (k-1) number of complex symbols output from the baseband modulator.
  • a zero insertion switch 3 and a CP addition unit 4 are provided to insert zero and make the data sampling rate k times the symbol rate (R).
  • symbol is a signal mapped in a complex plane by a baseband modulator
  • symbol rate is the number of complex symbols transmitted per unit time
  • Data sampling rate is the number of signals (including the symbol and code window) transmitted per unit time.
  • the CP adding unit 4 blocks the switch output every N samples, and copies and adds the L sample at the end of the block at the head and the L sample at the head of the block as the CP.
  • a band limiting filter 6 for removing unnecessary frequency components of the signal generated by the zero insertion is connected to the subsequent stage of the zero insertion switch 3.
  • intersymbol interference occurs only by band limiting, so a filter that satisfies the Nyquist condition at the time of reception or a filter that can suppress adverse effects due to intersymbol interference is used.
  • the band limiting filter 6 is composed of a root Nyquist filter having a Nyquist bandwidth of kR or more, a Gaussian filter having a 3 dB bandwidth of kR or more, or an approximate filter thereof. Examples of the approximate filter include a Thomson filter (Bessel filter). In FIG.
  • the data sampling rate is increased to kR force pkR before and after the band limiting filter 6. This is because it is necessary to expand the frequency capable of signal processing in order to limit the bandwidth. By increasing the sample speed in this way, the signal band is limited and unnecessary alias components can be removed by DZA.
  • this transmitter is provided with a circuit for inserting a pilot signal or a preamble at a predetermined position of the block so that the receiver can estimate the transfer function of the transmission path. ing.
  • the output signal of the band limiting filter 6 becomes an analog signal through the DZA converter 7 and is input to the orthogonal modulator 8.
  • the I and Q quadrature components are quadrature modulated and combined into one signal.
  • the signal is placed on a carrier wave and radiated from the antenna through the power amplifier 9.
  • FIG. 2 is a block diagram of a frequency diversity receiver paired with the frequency diversity transmitter. Also in this block diagram, signals between the quadrature demodulator 12 and the baseband demodulator 18 are assumed to be complex numbers. In actual hardware, two circuits corresponding to two orthogonal components, 1 (real part) and Q (imaginary part), are configured in parallel.
  • a signal received by the antenna is converted from a radio frequency band to an intermediate frequency band through a low noise amplifier and input to the quadrature demodulator 12.
  • I and Q are converted into two orthogonal signals, and each is converted into a complex digital signal through the AZD converter 13.
  • This complex digital signal passes through a band limiting filter 14 having the same pass characteristics as the band limiting filter 6 of the transmitter.
  • the band limiting filter 14 removes unnecessary components other than the transmitted signal.
  • the signal that has passed through the band limiting filter 14 passes through the thinning filter 15 that extracts only the samples necessary for signal determination from all the received samples, and the CP added by the frequency diversity transmitter.
  • the CP removal unit 16 to be removed and the transfer function estimation unit 19 are entered.
  • the fractional interval equalizer 17 performs an AZD conversion with an integer multiple of the transmission signal (in the case of 2 n times, DF Sampling (oversampling) the waveform at a speed of T (FFT to reduce the amount of calculation) and performing equalization processing reduces ISI (intersymbol interference).
  • a fractional interval equalizer (FSE) 17 performs a discrete Fourier transform on the received signal block after CP removal. Then, frequency domain equalization processing is performed based on the frequency transfer function. Frequency domain equalization is a process of multiplying equalizer weights for each frequency component in the transform domain. Then, discrete inverse Fourier transform is performed on the equalized signal to convert it into a time function.
  • FSE fractional interval equalizer
  • the equalizer weight is obtained by estimating the transfer function of the transmission path on the receiver side. For convenience of estimation, as described above, a pilot signal or preamble is inserted at a predetermined position of a block of transmission signals.
  • the least square error reference weight at the time of oversampling k times can be adopted.
  • the least square error reference weight is expressed by the following equation, for example.
  • s 2 is the variance of the transmitted signal
  • ⁇ 2 is a variance value of noise.
  • the formula is shown on the assumption that the receiver noise is white noise, but the present invention can also be applied to the case of general receiver noise that is not white.
  • FIG. 3 is a block diagram showing processing of the fractional interval equalizer 17.
  • the fractional interval equalizer 17 includes a weighting processing unit 31 for powering the equalizer weight and an adding unit 32.
  • the input of the weighting processing unit 31 after the Fourier transform that has been oversampled by k times is expressed as X, ⁇ X (X in the case of representation).
  • the adder 32 calculates the weight
  • the sampled received signal is Fourier transformed (b) and weighted.
  • the equalizer weight is applied in the processing unit 31 (c).
  • the oversampling has been performed twice, but in general, the same can be shown for oversampling k times (k ⁇ 2).
  • Baseband demodulator (Dem a pper) 18 restores the original transmission signal by estimating a complex symbol that has been transmitted from the transmit unit from the inverse Fourier transformed complex signals.
  • the fractional interval equalization function is provided on the receiving side, but the signal processing load on the receiver can be reduced by moving to the transmitting side.
  • FIG. 5 is a block diagram showing a frequency diversity transmitter having a fractional interval equalization function
  • FIG. 6 is a block diagram showing a receiver not having a fractional interval equalization function.
  • FIG. 5 and FIG. 6 the same circuits as those in FIG. 1 and FIG. 2 are given the same numbers, and redundant explanations are omitted.
  • the frequency diversity transmitter in FIG. 5 includes a fractional interval equalizer 10 between the zero insertion switch 3 and the CP adding unit 4.
  • the fractional interval equalizer 10 is connected to the transfer function estimation unit 11.
  • the receiver in FIG. 6 does not include the fractional interval equalizer 17.
  • FIG. 7 shows the structure of the fractional interval equalizer 10 on the transmitter side.
  • the fractional interval equalizer 10 is provided with a weighting processing unit 31 for powering the equalizer weights, like the fractional interval equalizer 17 shown in FIG.
  • the force fractional interval equalizer 10 does not include the adding unit 32. This is because the frequency diversity transmitter transmits the extra signal spread as much as k times as it is, so there is no need to add.
  • the zero insertion switch 3 and the fractional interval equalizer 10 may be one.
  • DFT Discrete Fourier Transform
  • K signals after Fourier transform are generated, and equalization weights y 1, ..., y are respectively generated.
  • IDFT Inverse Discrete Fourier Transform
  • the weighted processing unit 31 multiplies the equalized weight for the frequency-converted signal (d).
  • the function form of the equalization weight is calculated based on the transfer function of the transmission line. At this time, the equalization weight extends to twice the frequency corresponding to the sample speed.
  • the frequency domain equalized signal (e) is subjected to inverse Fourier transform and returned to the time domain (f).
  • the signal with the cyclic prefix described above, application of a band limiting filter, quadrature modulation, etc. are converted to a radio frequency and transmitted as a radio signal.
  • the equalizer weight used in the weighting processing unit 31 on the transmitter side can be estimated only on the receiver side that receives the signal. Therefore, if fractional interval equalization is performed at the transmitter, information on the transfer function of the receiver power transmission path must be acquired.
  • the transfer function estimation unit 11 has a function of acquiring information on the transfer function.
  • the transceiver supports bidirectional communication
  • the communication method is TDD (Time Division Duplex), which transmits and receives signals on the same frequency channel, the frequency is the same for both transmitted and received signals, so transfer function estimation
  • the unit 11 can use the estimated transfer function as it is as the equalizer weight of the transmission signal.
  • the transfer function estimation unit 11 puts the transfer function estimated on the receiver side on the data on the transmitter side It is necessary to return to and import. For this reason, when a signal is transmitted from the receiver to the transmitter, the receiver needs to send transfer function data.
  • the transmission path provided between the transmitter and the receiver may be used as it is! ! /, assuming that).
  • other network transmission paths such as the Internet, ISDN, and cellular phone may be used without using the transmission path.
  • FIGS. 9 to 13 show examples of waveforms at various parts of the transceiver.
  • Table 1 shows the specifications used in the calculations in Figs.
  • the root Nyquist filter can represent filter coefficients only in real numbers, the real and imaginary parts of complex digital signals can be handled independently.
  • the time waveform below shows the real part, and the frequency waveform shows the amplitude value.
  • FIG. 9 (a) shows the signal waveform of the real part at the output point (1) of the baseband modulator 2 in FIG.
  • Figure 9 (b) shows the discrete Fourier transform of the signal at output point (1). Since QPSK modulation is assumed in this example, the real part and imaginary part of the signal output from the baseband modulator 2 take the values 1Z 2 and 1Z 2.
  • FIG. 10 (a) shows the signal waveform at point (2) that has passed through zero insertion switch 3 with the symbol rate kept the same as in FIG. 9 (a).
  • Figure 10 (b) shows the discrete Fourier transform of the signal at point (2).
  • the bandwidth is doubled compared to Fig. 9 (b).
  • the right half of the signal spectrum in Fig. 10 (b) is a copy of the original signal spectrum.
  • FIG. 10 (b) shows the signal waveform at point (2) that has passed through zero insertion switch 3 with the symbol rate kept the same as in FIG. 9 (a).
  • Figure 10 (b) shows the discrete Fourier transform of the signal at point (2).
  • the zero sampling switch 3 interpolates the value 0 to the signal waveform 1Z 2, —l /
  • FIG. 11 (a) shows a signal waveform at point (3) that has passed through the band limiting filter 6.
  • Figure 11 (b) shows the frequency spectrum at point (3). It can be seen that when the frequency is 5MHz or higher, the component is attenuated and the waveform is smooth.
  • FIG. 12 (a) shows the signal waveform at point (4) that has passed through the band limiting filter 14 in the receiver of FIG. Figure 12 (b) shows the frequency spectrum of point (4).
  • FIG. 13 (a) shows a signal waveform at point (5) that has passed through the decimation filter in the receiver.
  • Figure 13 (b) shows the discrete Fourier transform of the signal at point (5). By passing through the decimation filter, the same signal waveform as in Fig. 10 (a) is restored.
  • a frequency diversity signal with k branches and a data sampling rate of k times (in this embodiment, twice) can be obtained.
  • the number of transmitters required is the same as the number of branches, but only one transmitter is required in this configuration.
  • the conventional frequency diversity transmitter requires a guard band to separate each branch signal with a filter. This configuration does not have a guard band.
  • a function for feeding back the propagation path condition from the receiver to the transmitter is added to the frequency diversity transmitter / receiver so that the transmitter can operate each related parameter to change the method to a variable rate. It is possible to extend this to an adaptive modulation system.
  • FIG. 14 is a block diagram of a frequency diversity receiver in the present transmission / reception system.
  • the frequency diversity receiver includes a low noise amplifier, a quadrature demodulator 12, an AZD converter 13, a band limiting filter 14, a CP removal unit 16, an equalizer 17, and a baseband demodulator 18.
  • the connection is the same as that of the receiver shown in Figure 2.
  • a transfer function estimation unit 19 and a transmission quality evaluation unit 19 are provided. ing. Note that the receiver includes all of the signal strength measuring unit 21, the BER measuring unit 22, and the transfer function estimating unit 19, but may include V, one or two of them. But ⁇ ⁇
  • the transmission quality evaluation unit grasps the state of the propagation path based on the output of any one of these signal strength measurement unit 21, BER measurement unit 22, and transfer function estimation unit 19 (evaluates transmission quality). ).
  • the time interval for evaluating the transmission quality can be arbitrarily selected, the shorter the time interval is better, considering that the state of the radio transmission channel changes in a considerably short time.
  • the transmission quality may be evaluated once every time one block of the received signal is received.
  • the amount of information transmitted from the transmitter to the receiver may be reduced. In that case, there is a trade-off with the amount of information to be transmitted.
  • the modulation multi-value number or symbol rate is determined on the receiver side, and the result is sent to the transmitter, or (ii) the evaluated transmission quality. This value is transmitted to the transmitter, and the modulation multi-level number or symbol rate is determined on the transmitter side. Either method (ii) or (ii) may be adopted, but the following explanation is based on the method (ii).
  • the receiver secures information transmission means from the receiver to the transmitter in order to feed back the modulation level or symbol rate to the transmitter.
  • a network transmission line such as the Internet, IS DN, or mobile phone may be used instead of the wireless transmission line.
  • information is generally embedded in specific bits of the control packet.
  • FIG. 15 is a flowchart showing a procedure for transmitting the transmission quality information to the transmitter as well as the receiver power.
  • the modulation level or symbol rate To determine if it needs to be changed (step S2). This criterion will be described later. If it is determined that the modulation multi-value number or symbol rate needs to be changed, the control packet is rewritten and transmitted to the transmitter side (step S3). At the same time, the settings such as the demodulation method, symbol rate, bandwidth of the band limiting filter 14 and inverse Fourier transform size in the receiver are changed (step S4).
  • FIG. 16 is a flowchart showing a procedure for changing the setting in the transmitter that has received the transmission quality information.
  • the transmitter determines whether it is necessary to change the number of modulation levels or the symbol rate (step T2), and modulates the modulation scheme, symbol rate, and bandwidth limitation in the transmitter. Change the settings such as the bandwidth of filter 14 (step ⁇ 3).
  • a criterion for changing a symbol rate or the like from the transmitter to the receiver is represented as a table.
  • the transmission quality is evaluated based on the methods (1) to (3) described above based on the outputs of the signal strength measuring unit 21, the BER measuring unit 22, and the transfer function estimating unit 19.
  • the transmitter of the embodiment of the present invention provides 64QAM, 16QAM, and QPSK as transmission signal modulation schemes.
  • FIG. 17 is a map showing an example of determining the modulation scheme and symbol rate according to the BER value.
  • the symbol rate is lowered even with the same QPSK.
  • the zero insertion rate k is increased in accordance with the rate at which the symbol rate is reduced, so that the final data sampling rate does not change.
  • the data sampling rate of the AZD converter 13 output is a fixed number 8R0 regardless of the modulation multi-level number and the symbol rate.
  • the size of the discrete Fourier transform of the fractionally spaced equalizer (FSE) is a fixed number M.
  • the data sampling rate does not change even if the modulation multi-level number or symbol rate is changed, and the sampling rate and FFT size of DZA and AZD conversion are common. It can be said that it is advantageous in terms of mounting.
  • the embodiments of the present invention are not limited to the above-described embodiments.
  • the present invention relates to an OFDM system that is not limited to an SCBT system. Even applicable.
  • OFDM a signal that has been subjected to inverse Fourier transform by the transmitter is transmitted, so that the receiver does not need a means for performing inverse Fourier transform.
  • the band limiting filter 14 of the receiver does not necessarily have the same force as described that the pass characteristics are the same as the band limiting filter of the transmitter. If the signal is received correctly, you can use a filter with different pass characteristics!

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Abstract

Dans la présente invention, un système d'insertion de zéros (3) sert à insérer (k - 1) zéros entre les données adjacentes d'un signal de bande de base complexe, plaçant ainsi (k - 1) copies adjacentes du spectre de fréquence du signal de bande de base complexe, avant l'insertion de zéros, et agrandissant ensuite la bande passante occupée d'un signal de transport comme avant l'insertion de zéros à k fois (où k ≥ 1). Un filtre de limite de bande (6), possédant une bande passante Nyquist égale ou supérieure à kR, sert lorsque T est un intervalle de temps entre les données adjacentes du signal de bande de base complexe, T/k est un intervalle de temps entre les données adjacentes, comme après l'insertion de zéros, et que T = 1/R. Un signal complexe passant à travers le filtre de limite de bande (6) est soumis à une modulation de quadrature, puis transmis. Une structure simple peut servir à obtenir un effet de diversité de fréquence, même dans un cas de mauvaise qualité de transmission.
PCT/JP2006/303073 2005-08-02 2006-02-21 Transmetteur, récepteur, procédé de communication et système de transmission/réception Ceased WO2007015317A1 (fr)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010093378A (ja) * 2008-10-03 2010-04-22 Nippon Telegr & Teleph Corp <Ntt> 信号受信装置、信号受信システム及び信号受信方法
JP2010093379A (ja) * 2008-10-03 2010-04-22 Nippon Telegr & Teleph Corp <Ntt> 信号受信装置、信号受信システム及び信号受信方法
JP2010124334A (ja) * 2008-11-20 2010-06-03 Nippon Telegr & Teleph Corp <Ntt> 信号受信装置及び方法
WO2012132191A1 (fr) * 2011-03-29 2012-10-04 パナソニック株式会社 Dispositif de réception

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