WO2007006202A1 - Système et procédé de transmission qotdma - Google Patents

Système et procédé de transmission qotdma Download PDF

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Publication number
WO2007006202A1
WO2007006202A1 PCT/CN2006/001304 CN2006001304W WO2007006202A1 WO 2007006202 A1 WO2007006202 A1 WO 2007006202A1 CN 2006001304 W CN2006001304 W CN 2006001304W WO 2007006202 A1 WO2007006202 A1 WO 2007006202A1
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filter
synchronization
unit
channel
sample
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PCT/CN2006/001304
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English (en)
Chinese (zh)
Inventor
Kechu Yi
Yong Wang
Hua Dong
Hongfeng Yi
Hongxin Tian
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Xidian University
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Publication of WO2007006202A1 publication Critical patent/WO2007006202A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/02—Channels characterised by the type of signal
    • H04L5/06—Channels characterised by the type of signal the signals being represented by different frequencies

Definitions

  • the invention belongs to the field of communication technology and relates to data transmission, in particular to a time-division multiplexing transmission method and a communication system constructed by the method, which are applied to digital communication. Background technique
  • Orthogonal Time Division Multiplexing Orthogonal Time Division Multiplexing
  • OFDM Orthogonal Frequency Division Multiplexing
  • Tao a series of information transmission technology
  • OFDM utilizes this translational orthogonality of the Sine function to enable multiple sub-band signals that overlap each other in the frequency domain to be separated from each other, thereby achieving a desired band efficiency.
  • OFDM utilizes this translational orthogonality of the Sine function to enable multiple sub-band signals that overlap each other in the frequency domain to be separated from each other, thereby achieving a desired band efficiency.
  • EFA'2003 proposes an OTDM method, which is implemented by the orthogonality of Golay complementary sequences, which is different from the OTDM implemented by the Sine function translation orthogonality described above.
  • QOTDM of this patent proposes an OTDM method, which is implemented by the orthogonality of Golay complementary sequences, which is different from the OTDM implemented by the Sine function translation orthogonality described above.
  • quadrature-orthogonal in QOTDM can be understood as follows: Although we can not use the translational orthogonal Sine function as the shaping wave, multiple discrete signal sample sequences are sample-interleaved and time-division multiplexed in one waveform channel. However, we can design the frequency domain response as the raised cosine characteristic according to the Nyquist first criterion, and the shaped wave with the time domain "Sine function" constitutes the waveform channel, so that multiple discrete signal sample sequences can be interleaved with samples. Time division multiplexing is transmitted in this waveform channel. Although this shaped wave is very similar to the Sine function, it only has an approximate translational orthogonality, which is easy to express from its form.
  • the V discrete signal sample sequences transmitted by using the above QOTDM may be sample sequence samples of N consecutive bands of arbitrary continuous signals, and therefore may also be equivalent low-pass signals of V digital modulated signals, ie, complex envelopes.
  • the baseband signal also called the "zero intermediate frequency" digital modulation signal sample sequence, we multiplex the small and discrete samples after the sample interleaving.
  • a continuous signal is transmitted over the corresponding continuous channel.
  • Waveform-forming finite impulse response FIR filter we design the frequency response of this filter as a square root raised cosine characteristic, and use the same FIR filter as the channel matching filter at the receiving end. Assuming that the characteristics of the entire channel are mainly determined by the overall characteristics of the two filters, and designed to conform to the frequency domain raised cosine characteristic of the Nyquist first criterion, then the correct channel is matched at the receiving end.
  • the signals can be recovered without distortion, and crosstalk between the subchannels does not occur. If we send the position of the discrete sample sequence of the transmitting end to the position before the time tapping of the receiving end, it is regarded as a discrete channel, when the total characteristics of the channel are not in accordance with the Nyquist first criterion. , we can use the channel equalizer to compensate, so that it meets the Nyquist first criterion, and then time-division tapping, can avoid mutual crosstalk between sub-channels.
  • Such a QOTDM system that transmits multiple consecutive signals or a sequence of discrete samples thereof has significantly different index requirements than a TDM system that transmits multiple general data streams, because its performance should be recovered.
  • the magnitude of the distortion of each signal and the signal-to-noise ratio are measured, rather than measured by bit error rate as in digital communications. For example: It allows each signal to be scaled up or down.
  • the sample value of the recovered signal allows a very high proportion of bit errors, such as 10-20%, to allow a certain amount of additive noise to be introduced, as long as each discrete sample
  • the distortion and signal-to-noise ratio of the point sequence can meet certain requirements.
  • multiple digital signals can be transmitted using conventional TDM and conventional digital modulation techniques.
  • Sample sequence but its frequency band utilization is much lower.
  • using QPSK modulation to transmit 30 channels of voice signals in TDM requires about 1.5MHz, and the band utilization rate is only 7%, and we use the QOTDM method to transmit the band utilization rate. Can be close to 100%, at least above 50%.
  • the QOTDM transmission mode can also be called the sample interleaved time division multiplexing transmission of multiple continuous signals, or simply referred to as continuous wave time division multiplexing, and the English expression is Continuous Wave Time-Division Multiplexing.
  • CWTDM Continuous Wave Time-Division Multiplexing
  • the basic principle of QOTDM or sample interleaving CWTDM can be described as follows: If a continuous signal with a V-channel bandwidth of Hertz is to be time-multiplexed into a continuous signal for transmission in a continuous channel, the transmitting end is first greater than The sampling rate of 2 ⁇ 3 ⁇ 4 Hz is used to sample the V-channel signal in turn, to obtain a sample sequence.
  • the sample sequence can be quantized or not quantized.
  • the sequence of the sample is squared by a Nyquist first criterion. After the cosine low-pass digital filter is filtered, D/A conversion is performed to obtain a continuous wave time division multiplexing signal.
  • the signal may be transmitted through a continuous channel.
  • the channel may be a cable channel baseband transmission, or may be moved to a radio frequency and transmitted by a narrowband wireless channel.
  • the sampling rate and the sampling position are exactly the same as the transmitting end, and By identifying the starting point of each frame, the sequence of samples of each signal and the corresponding continuous signal waveform can be recovered without distortion. Of course, if noise is introduced into the channel, the signal-to-noise ratio of the recovered signal will be correspondingly reduced.
  • the object of the present invention is to overcome the deficiencies of the prior art mentioned above, and to provide a quasi-orthogonal time division multiplexing transmission method and a communication system based on the same, to solve a plurality of continuous signals or sample sequence samples thereof interleaved by samples
  • the time division multiplexing method achieves high-precision frame synchronization and channel equalization when transmitted in a wireless channel.
  • the invention relates to a quasi-orthogonal time division multiplexing transmission method, which is used for constructing a communication system, and multiplexes a TV continuous signal with a bandwidth of Hertz or a sequence of sample samples thereof into a continuous signal and transmits through a continuous channel; After receiving the QOTDM continuous signal transmitted from the originating end, the receiving end converts into a "zero intermediate frequency, complex digital signal, and uses a carrier phase-locked loop to correct the frequency offset of the zero-IF" complex digital signal by orthogonal down-conversion and sampling digitization.
  • the frame synchronization loop is used to realize high-precision sample synchronization, and the adaptive channel equalizer is used to correct the channel change, and then the time-division tapping is performed to recover the transmitted N signals.
  • the specific process of the transmission method of the present invention is as follows:
  • the input end firstly samples the parsing signals of the N consecutive signals at a sampling rate of N.sample/sec, and realizes the interleaving time division multiplexing, wherein 2 ⁇ ⁇ ⁇ 3 ;
  • the above complex sample sequence is modulated into a continuous signal of bandwidth (1+ «) ⁇ + ⁇ Hertz, wherein the waveform shaping filter is designed to be zero phase according to the Nyquist first criterion.
  • Shift FIR filter whose frequency response is approximately squared to raise the cosine characteristic, "for its roll-off factor, 0 ⁇ «: ⁇ 1;
  • the output sample rate is a complex sample sequence of F s samples/second.
  • a transmission system based on the above orthogonal time division multiplexing transmission method includes:
  • the sample interleaving time division multiplexing unit is configured to perform the sample interleaving time division multiplexing of the sample sequence of the input N consecutive complex signals to obtain a complex sample order with a sample rate of the sample point/second.
  • a synchronization and pilot sequence generating unit for generating a synchronization and pilot sequence, and inserting the sequence into the above complex sample sequence to obtain a sequence sequence of (N+) ⁇ complex samples;
  • a QAM modulator for modulating the complex sample sequence into a narrowband continuous signal having a bandwidth of (l+a)(N+). Hertz, where 0 ⁇ 1.
  • the receiving system of the quasi-orthogonal time division multiplexing transmission method includes an orthogonal down converter, a frequency offset correcting unit, a channel matched filter, an adaptive transversal filter, a synchronization and pilot sequence matched filter, and a frequency offset phase shift amplitude Estimation unit, coefficient modification amount calculation unit, synchronization timing and residual error estimation unit, 2:1 down sampling unit and time division tap unit;
  • the orthogonal down converter converts the received signal into a "zero intermediate frequency" complex digital signal, and sends
  • the frequency offset correction unit realizes the frequency offset correction, and after passing through the channel matching filter, the obtained signal is divided into two ways by the adaptive transverse filter filtering: after being sent to the synchronization and pilot sequence matched filter processing,
  • the three channels are simultaneously sent to the synchronization timing and its residual error estimating unit, the frequency offset phase offset amplitude estimating unit and the coefficient modification amount calculating unit, respectively performing frame synchronization timing and its residual error estimation, frequency offset estimation and channel estimation, and the other is sent to
  • the receiving system further includes a target channel response generating unit and a polyphase filter bank a coefficient memory, an out-of-synchronization judgment and capture/tracking switching unit and a loop filter;
  • the target channel response generation unit and the adaptive transversal filter, the coefficient modification amount calculation unit, and the pilot sequence matched filter filter constitute An adaptive channel equalizer to achieve a total channel characteristic capable of satisfying a Nyquist criterion;
  • the polyphase filter bank coefficient memory, the out-of-synchronization judgment and capture tracking switching unit and the loop filter 1 and the coefficient can be Variable channel matched filter, adaptive transversal filter, synchronization and pilot sequence matched filter, synchronization timing and residual error estimation unit form a frame synchronization loop for achieving high-precision sample synchronization;
  • 2 and the frequency offset correction unit, the adaptive transversal filter, the synchronization and pilot sequence matched filter, the frequency offset and phase offset estimation unit, and the channel matched filter with variable coefficients constitute a carrier synchronization loop, which is used to implement Carrier synchron
  • the medium synchronization and pilot sequence matched filter is a FIR filter of length 4K' (N + M), l ⁇ Jf ⁇ 50, and the filter appears as a comb filter in the frequency domain, combing
  • the width of the tooth is determined by the number of cycles K included in the synchronization and pilot sequence matching filter coefficient length, and the output is subtracted from the output of the target channel response unit and sent to the coefficient modification amount calculation unit for the adaptive transverse filter.
  • the coefficients are modified to achieve adaptive equalization of the system.
  • the polyphase filter coefficient memory has a set of FIR filter coefficients, 10K 0 , and the filter formed by each set of coefficients is a matched filter of the hair shaping filter, and the group delay values are not mutually exclusive.
  • the adaptive channel equalizer realizes that the total channel characteristic can satisfy the Nyquist first criterion by filtering the synchronization and pilot sequence matched filter, and processing the signal output by the adaptive transversal filter to obtain The channel response is estimated, and the estimation of the channel response is subtracted from the target channel response generated by the target channel response generating unit, and then sent to the coefficient modification amount calculation unit to update the coefficients in the adaptive transversal filter, so that the channel equalization is achieved.
  • the frame synchronization loop realizes high-precision sample synchronization, and the estimated synchronization residual deviation is input to the polyphase filter coefficient memory by the synchronization timing and the residual error estimation unit, and the group is most capable of synchronizing.
  • the filter coefficient with reduced residual deviation continuously updates the coefficients of the channel matched filter, so that the group of signals should be changed and the synchronization deviation is gradually reduced to realize synchronous tracking.
  • the correlation peak search is performed in the time-frequency offset two-dimensional domain to realize synchronous acquisition, and the frequency offset and the frame synchronization point determined by the capture process are used as initial parameters to start the partial correction unit and the frame synchronization loop steering tracking.
  • the adaptive transversal filter and the channel matched filter may also adopt the same variable coefficient FIR filter, and the variable coefficient FIR filter is used as a channel equalizer after the system completes the synchronous acquisition steering synchronization tracking state.
  • Adaptive transversal filter may also adopt the same variable coefficient FIR filter, and the variable coefficient FIR filter is used as a channel equalizer after the system completes the synchronous acquisition steering synchronization tracking state.
  • the frame synchronization loop is composed of a variable coefficient FIR filter, a synchronization and pilot sequence matched filter, a synchronization timing and a residual error estimating unit thereof, a loop filter 1, an objective function storage unit, and a target channel response generating unit.
  • the synchronization timing and its residual error estimating unit filter the obtained synchronization residual error by the loop filter 1 and then send it to the target channel response generating unit, and select a group from the target function storage unit to reduce the synchronization timing residual error.
  • a small objective function is used to generate a target channel response sequence at the next moment to implement tracking of the frame synchronization loop.
  • the quasi-orthogonal time division multiplexing transmission method wherein the synchronization and pilot sequence adopts a periodic complex pseudo-random sequence with a period of 2M and a spectrum having only odd harmonic components, and the sequence is interspersed evenly at intervals
  • the sample is interleaved and time-multiplexed within the sequence of samples, that is, every N/M samples are inserted into one, and a sample rate is (N+).
  • the complex sample sequence is followed by two adjacent samples. Insert a 0 value sample between the points to obtain a sampling rate of 2 ⁇ +.
  • the complex sample sequence is followed by two adjacent samples. Insert a 0 value sample between the points to obtain a sampling rate of 2 ⁇ +.
  • the present invention filters signals with different group delay filters, it is equivalent to interpolating and resampling the signals, so the synchronization accuracy can be much smaller than a sample interval, and the frame synchronization loop is used to ensure its robustness. Sex.
  • the basic principle of this kind of synchronization loop based on polyphase filter bank Although the paper "a high-precision symbol timing synchronization method" has been published in Journal of Xidian University, 2005, No. 6, but the specific structure and practice of the present invention It was not in the past. Theoretical analysis and simulation verification show that this method can make the accuracy of frame synchronization and sample synchronization reach 1% under certain conditions, that is, 0.5/R sampling intervals. 2. Solved the channel equalization problem.
  • the channel estimation for channel equalization in the present invention is very ingenious, and the pilot sequence is a synchronization code, which is a periodic pseudo-random code sequence whose period is twice the period of the multiplexed frame period, and the spectrum is only odd harmonic The wave component, even harmonic components are all equal to zero.
  • the training sequence is interspersed in the multiplexed signal. After the channel is transmitted, the time domain waveform and the multiplexed signal waveform overlap each other, but in the frequency domain, the two are separated from each other, because the frequency of the multiplexed signal is one. A quasi-periodic spectrum, and there is no energy near the odd harmonics of the training sequence.
  • the sync and pilot sequence matched filter is a comb filter whose width of the comb is determined by the number of periods included in the sync code matching filter coefficient length.
  • the synchronization code matching filter can well eliminate the influence of other multiplexed signals and accurately extract the response of the training sequence through the actual channel.
  • the value should be as small as possible. In this case, as long as the spectrum width of the multiplexed signal is properly designed, the two can be well separated and a good channel response estimate can be obtained.
  • the output of the synchronization and pilot sequence matched filter of the present invention can provide accurate amplitude information, and high-precision frame synchronization and sample synchronization information ensure accurate target channel response and can be quickly follow the changes in the received signal parameters.
  • the adaptive filter coefficients are continuously modified with the minimum mean square error as a criterion to achieve high quality channel equalization that quickly follows channel variations.
  • the high-precision frame synchronization and the excellent channel equalization characteristic of the invention ensure that the QOTDM signals transmitted by the QAM modulation/demodulation method are well separated at the receiving end, so that the signal distortion and the mutual leakage crosstalk between the subchannels are reduced. Small enough to be ignored.
  • FIG. 1 Schematic diagram of the transmission part of the QOTDM system of the present invention
  • FIG. 2 is a block diagram of the receiving part of the QOTDM system of the present invention
  • FIG. 3 is a block diagram of the receiving part of the QOTDM system of the present invention
  • Figure 4 is a diagram of a high-speed data transmission system based on QOTDM of the present invention
  • a quasi-orthogonal time division multiplexing transmission method and a communication system constructed by the method of the present invention multiplex a TV continuous signal having a bandwidth of B Hz or a sample sequence thereof into a continuous signal. Continuous channel transmission.
  • the transmitting part of the system consists of a sample interleaving time division multiplexing unit, a synchronization and pilot sequence generating unit, two 1:2 sampling rate boosting units, two shaping filters, two D/A converters, two A low-pass filter and a quadrature up-converter are formed, and the relationship between the units of the transmitting part is sent as follows:
  • the continuous analysis signal of the TV channel discrete signal input is sampled in turn at the sampling rate of N. sample point/second, and the sample interleaving time division multiplexing is realized, and the sample interleaving and time division multiplexing signals are obtained, wherein 2 ⁇ ⁇ 3 ;
  • the sample interleaving and time division multiplexing unit inserts the synchronization and pilot sequences output by the synchronization and pilot sequence generating unit into the sample interleaving and time division multiplexing signals, and the insertion manner may be two, one in each frame.
  • the front or back of the complex sample is continuously inserted, and it can also be inserted therein.
  • This patent designs a special synchronization and pilot sequence, and is interspersed in the middle of the multiplexed signal with a uniform spacing.
  • the sampling rate boosting unit inserts the inserted synchronization and pilot sequences obtained in the previous step into the sample interleaving and the time division multiplexing signal to insert a zero value sample between each two adjacent samples, After the sampling rate is doubled, QAM modulation is performed, that is, the real part and the imaginary part are respectively subjected to a shaping filter, a DAC, a low-pass filter, and an orthogonal up-converter, thereby converting the input TV channel discrete signal. For a bandwidth of (1+ «) ⁇ + ⁇ .
  • the waveform shaping filter is designed as a zero-phase-shift FIR filter according to the Nyquist first criterion, and its frequency response is approximately square root raised cosine characteristic, ⁇ For its roll-off factor, 0 ⁇ 1.
  • the transmission of the present invention can be any one of a wired channel, a wireless channel, an optical channel or a underwater acoustic channel. Send in the continued channel.
  • the receiving part is composed of an orthogonal down converter, a channel matching filter with variable coefficients, a synchronization and pilot sequence matched filter, a carrier phase locked loop, a frame synchronization loop, and It is composed of an adaptive channel equalizer, two 2:1 downsampling units and a time division tapping unit.
  • the carrier phase-locked loop is composed of a loop filter 2 and a frequency offset correction unit, an adaptive transversal filter, a synchronization and pilot sequence matched filter, a frequency offset and phase offset estimation unit, and a channel matching filter with variable coefficients.
  • the adaptive channel equalizer is composed of the target channel response generating unit and the adaptive transversal filter, the coefficient modification amount calculating unit, and the pilot sequence matched filter; the frame synchronization loop is replaced by the polyphase filter bank coefficient memory, Step judgment and capture/tracking switching unit and loop filter 1, variable channel matching filter, adaptive transversal filter, synchronization and pilot sequence matched filter, synchronization timing and residual error estimating unit.
  • the receiving end receives the bandwidth transmitted by the originating terminal (1+aXN+ k. After the Hertz continuous signal, it becomes a zero-intermediate frequency complex digital signal by orthogonal down-conversion and sampling digitization to a sampling rate of 2(N+). :
  • v(mT) is the channel noise), which is the frequency offset and phase offset introduced in the signal due to the relative deviation of the receiver and transmitter clocks;
  • the frequency offset estimation unit in the carrier phase-locked loop estimates the frequency offset by using the output of the synchronization and pilot sequence matched filter, and uses a loop filter to process the frequency offset estimate, and sets it to ⁇ , and sends it to the frequency offset correction unit. It is used to correct the "zero intermediate frequency," the frequency offset existing in the complex digital signal received by the receiving end, that is, r(). If the receiver uses a numerically controlled oscillator NCO-based digital quadrature downconverter to extract the baseband. For the complex envelope signal, the above-mentioned frequency offset correction unit can be omitted, and the frequency offset estimate is directly fed back to
  • the NCO changes its oscillation frequency to gradually reduce the frequency offset of the output signal.
  • the received signal is processed successively by frequency offset correction, channel matched filter and adaptive transversal filter, and then sent to the synchronization and pilot sequence matched filter for filtering, and the output is the channel response estimation; the channel estimation and the target channel are used.
  • the target channel response generated by the response generating unit is subtracted, it is sent to the coefficient modification amount calculation unit to calculate the modification amount of each coefficient in the adaptive transversal filter, and the coefficients are correspondingly modified, and then the adaptive transversal filter continues to filter, so that the loop Channel equalization is achieved; the generation of the target channel response is achieved by using the synchronization and pilot sequences generated by the undistorted channel, combined with the timing and amplitude estimation information provided by the frame synchronization loop.
  • the ultimate goal of channel equalization is to bring the total channel characteristics closer to the Nyquist first criterion.
  • the synchronization and pilot sequence matched filter is designed as a 4 (N+)-length FIR filter whose impulse response is intercepted by the interpolated synchronization and pilot sequences, and the non-synchronous and pilot sequences are The sample is set to 0, then inverted, and the complex number is obtained by conjugate, where 1 ⁇ 50.
  • the received signal is processed successively by frequency offset correction, channel matching filter and adaptive channel equalization filtering, and then sent to the synchronization and pilot sequence matched filter for filtering;
  • the filtered signal is sent to the synchronization timing and its residual error estimating unit, Calculate the energy of each complex sample, and find the relevant peak position according to the energy-time curve thus obtained, realize the frame synchronization timing, and find the residual deviation after the synchronization timing according to the symmetry of the correlation peak;
  • the path filter is processed, it is sent to the coefficient replacement unit of the channel matched filter to find a set of filter coefficients which can minimize the synchronization residual deviation from the polyphase filter coefficient memory according to the magnitude of the residual deviation.
  • the coefficients of the channel matched filter are replaced so that the filtering is continued with the new filter coefficients.
  • the frame synchronization loop and the carrier phase-locked loop perform the following synchronization acquisition before entering the synchronization tracking:
  • the frequency offset correction unit performs frequency offset correction processing on the received signal by using various possible frequency offset guesses, and generates multiple frequency offsets differently.
  • the zero-IF complex signal is sent to the channel matched filter and the adaptive channel equalization filter for processing, and then sent to the synchronization and pilot sequence matched filter for filtering, and then sent to the synchronization timing and its residual error estimation unit respectively.
  • each find an energy-time curve Find the position of the highest correlation peak of the multiple curves in a frame synchronization code period, thereby determining the coarse estimate of the frequency offset and the frame synchronization point, and using these two estimates as initial parameters to start the carrier phase-locked loop and frame synchronization Loop, while tracking operation.
  • the present invention provides a simplified implementation scheme of a receiving end of a communication system based on a QOTDM transmission method.
  • the difference between this scheme and the scheme of Figure 2 is:
  • variable coefficient FIR filter uses channel matching filter with zero group delay for frame matching filtering during frame synchronization acquisition, and the variable coefficient FHI filter is used as a channel equalizer after the system completes the synchronous acquisition steering synchronization tracking state.
  • Adaptive transversal filter is used as a channel equalizer after the system completes the synchronous acquisition steering synchronization tracking state.
  • variable coefficient FIR filter adopts the filter coefficient determined by the above synchronous acquisition process as its initial value, and the filter coefficient is continuously fine-tuned by the adaptive algorithm to make the output of the synchronization and pilot sequence matched filter and the target channel response The mean square value of the difference between the sequences is kept to a minimum to achieve channel equalization.
  • the frame synchronization timing and the residual residual error obtained by the residual error estimating unit are loop-filtered, and then sent to the target channel response generating unit for selecting a group from the objective function memory to minimize the synchronization timing residual error.
  • a small objective function is used to generate a target channel response sequence at the next moment, thereby implementing tracking of the frame synchronization loop; whether the system is out of synchronization is mainly determined according to the size of the normalized correlation peak, and is judged as being less than a predetermined threshold.
  • the system loses synchronization and immediately switches from the channel equalization/synchronization tracking state to the state of re-synchronization acquisition.
  • This implementation saves a tens of orders of complex FIR filters, and channel equalization and The step tracking function can be successfully implemented.
  • the present invention provides a QOTDM system implementation for single transmission.
  • the originator firstly passes the input data bit through the channel coding and the 1:V serial/parallel conversion to obtain N data streams, and each digital data is digitally modulated to generate a complex signal sample sequence with a bandwidth of B Hz, and then according to the first
  • the step of the embodiment performs the sample interleaving time division multiplexing and QAM modulation, and becomes a continuous signal and then transmits through the channel; the receiving end is tapped and divided according to the steps described in an embodiment to obtain iV multiple samples.
  • This data transmission method mainly utilizes a superior adaptive channel equalizer to eliminate the scattering effect and multipath effect in the wireless channel. Therefore, it can also be combined with channel coding to further improve its transmission characteristics.
  • the purpose of using this QOTDM method for transmission of a data stream is mainly to better perform channel equalization and better combine coding and modulation to eliminate channel scatter or multipath fading and improve channel transmission efficiency. And quality, because there is a channel equalizer with excellent performance in the present invention, and has a good frame structure, and it is convenient to flexibly adopt a coding modulation method with excellent performance.
  • the present invention provides a QOTDM implementation for on-board FDMA-CWTDM conversion.
  • QOTDM For the basic principle of the satellite communication system based on FDMA-CWTDM conversion on the star, refer to the reference "Improved Signal Time Division Multiplexing Transmission Method" of the Chinese Patent No. 981122846.7, but the CWTDM method used herein is the present invention.
  • a digital frequency division splitter is used for frequency division and splitting, and 30 "zero intermediate frequency, complex signals are obtained, and then QOTDM is used to implement sample interleaving time division multiplexing into a "zero intermediate frequency” complex signal, and then orthogonal.
  • the up-conversion is changed to the radio frequency and transmitted to the ground.
  • the ground station After receiving the QOTDM signal, the ground station performs time-division and tapping to output each signal.

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Abstract

L’invention concerne un système et procédé de transmission QOTDMA, qui permettent de résoudre un problème de fiabilité de transmission de plusieurs signaux continus à la manière d’un entrelace de point d’échantillonnage TDMA dans un canal sans fil. Un procédé de transmission QOTDMA est adapté pour constituer un système de communication. Ce procédé multiplie alors en un signal continu, les signaux continus N dont les largeurs de bande sont B ou leur séquence de point d’échantillonnage. Il les transmet ensuite par le biais de canal continu. Après la réception du signal continu QOTDMA transmis à partir de l’extrémité de transmission, l’extrémité de réception le convertit en un signal numérique complexe IF zéro par la conversion orthogonale de fréquence vers le bas et la numérisation d’échantillonnage. Ce procédé utilise le transporteur PLL pour corriger le décalage de fréquence du signal numérique complexe IF zéro, et se sert de la boucle de synchronisation de cadre adaptée à l’égalisateur de canal pour réaliser une synchronisation de point d’échantillonnage de haute précision et corriger la distorsion de canal ; il effectue finalement le démultiplexage de la division du temps et recouvre les signaux N transmis. Le procédé a l’avantage de la haute précision de la synchronisation de point d’échantillonnage et une bonne caractéristique d’égalisation de canal, de sorte qu’il peut être appliqué à un système de communication par satellite basé sur la conversion FDMA-CWTDM et à la transmission de données à haut débit dans un canal sans fil.
PCT/CN2006/001304 2005-07-11 2006-06-13 Système et procédé de transmission qotdma WO2007006202A1 (fr)

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CN110113280B (zh) * 2019-04-12 2021-11-23 杭州电子科技大学 一种猝发通信中抗频偏的gmsk解调同步方法
CN113225285B (zh) * 2021-04-22 2022-03-01 中国电子科技集团公司第五十四研究所 一种gmsk信号相干解调装置

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CN102025479A (zh) * 2009-09-21 2011-04-20 西安英诺视通信息技术有限公司 样点交织多路离散信号时分复用方法
CN102025479B (zh) * 2009-09-21 2013-09-18 西安英诺视通信息技术有限公司 样点交织多路离散信号时分复用方法
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CN109714142B (zh) * 2019-03-11 2020-05-05 西安电子科技大学 一种正交时分复用传输方法及系统
CN114845376A (zh) * 2022-04-24 2022-08-02 之江实验室 一种基于fpga的高速并行定时同步方法
CN114845376B (zh) * 2022-04-24 2023-09-05 之江实验室 一种基于fpga的高速并行定时同步方法
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