CN107911327B - FMT-based multi-carrier modulation and demodulation method and system for ship VDES system - Google Patents
FMT-based multi-carrier modulation and demodulation method and system for ship VDES system Download PDFInfo
- Publication number
- CN107911327B CN107911327B CN201711039728.5A CN201711039728A CN107911327B CN 107911327 B CN107911327 B CN 107911327B CN 201711039728 A CN201711039728 A CN 201711039728A CN 107911327 B CN107911327 B CN 107911327B
- Authority
- CN
- China
- Prior art keywords
- signals
- paths
- parallel
- filter
- equal
- 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.)
- Active
Links
Images
Classifications
-
- 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
- H04L27/2626—Arrangements specific to the transmitter only
- H04L27/2627—Modulators
- H04L27/2628—Inverse Fourier transform modulators, e.g. inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators
-
- 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
- H04L27/2655—Synchronisation arrangements
- H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation
- H04L27/2691—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation involving interference determination or cancellation
Abstract
The invention relates to a multi-carrier modulation and demodulation method and a multi-carrier modulation and demodulation system based on FMT (frequency modulated modulation) of a ship VDES (vertical double-diffusion evolution system), which are realized in a digital domain, and have stable structure and high reliability; the filter coefficient of the filter is reasonably selected, a strict filter bank is adopted among each subcarrier, the resource consumption is reduced, the processing method is simpler and easy to realize, the subcarriers are not mixed in the frequency domain, the ICI caused by the non-orthogonality of the subcarriers is avoided, and the realization complexity of the filter is reduced; the invention adopts the Inverse Fast Fourier Transform (IFFT) and Fast Fourier Transform (FFT) modes to replace the modulation and demodulation parts of each subcarrier, simplifies the system structure, reduces the realization complexity of the multi-carrier modulation and demodulation system, and solves the problems of resource shortage and high realization complexity caused by a plurality of groups of intermediate frequency modulators and intermediate frequency demodulators.
Description
Technical Field
The invention relates to a multi-carrier Modulation and demodulation implementation method based on a filtering multi-tone Modulation (FMT) technology in a VHF Data Exchange System (VDES) of a ship, in particular to a multi-carrier Modulation and demodulation method and a Modulation and demodulation System based on the FMT in the VDES of the ship, which are suitable for the conditions of more subcarriers and Inter-carrier Interference (ICI) and belong to the technical field of signal Modulation and demodulation of a ship-mounted System.
Background
The international telecommunication union ITU-R m.2092-0 recommendation 10 months 2015 proposes technical characteristics of VDES in a VHF water mobile frequency band, and makes corresponding regulations on communication technical characteristics of a VDE system in a VDES system, but does not make corresponding regulations on an implementation manner. In particular, the implementation of multi-subcarrier modulation and demodulation and ICI between subcarriers is not explicitly described.
At present, the technical scheme for the VDES system of the ship at home and abroad mainly comprises: the scheme based on the subcarrier independent modulation filtering structure independently realizes frequency mixing and filtering on each subcarrier, has large resource consumption and high realization complexity, and each subcarrier has poor orthogonality, thus causing system performance loss.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a multi-carrier modulation and demodulation method based on FMT for a ship VDES system, which avoids ICI caused by subcarrier non-orthogonality and reduces system implementation complexity and resource consumption.
Another object of the present invention is to provide an FMT-based multi-carrier modulation and demodulation system for a marine VDES system.
The above purpose of the invention is mainly realized by the following technical scheme:
the FMT-based multi-carrier modulation and demodulation method of the ship VDES system comprises the steps that a sending end carries out FMT modulation on M paths of sub-carrier signals to obtain M paths of radio frequency signals, and the M paths of radio frequency signals are sent to a receiving end, and the specific implementation method comprises the following steps:
m paths of parallel subcarrier signals are subjected to M-point IFFT processing to obtain M paths of parallel transform domain signals;
filtering the M parallel transform domain signals by adopting a sending filter bank to obtain M filtered signals, wherein the sending filter bank comprises M filters, and each filter comprises L filtered signalsCoefficients, where the ith filter coefficient of the mth filter is denoted as fm+M×lM is more than or equal to 0 and less than or equal to M-1, L is more than or equal to 0 and less than or equal to L-1, namely L filter coefficients F of the mth filtermExpressed as: fm＝{fm；fm+M；fm+M×2；…；fm+M×(L-1)}；
Carrying out rate promotion on the M filtering signals to obtain M paths of parallel up-sampling signals, and converting the M paths of parallel up-sampling signals into a path of serial baseband signal;
performing quadrature modulation on the path of serial baseband signal to obtain an intermediate frequency signal; carrying out up-conversion on the intermediate frequency signal to obtain a radio frequency signal, and sending the radio frequency signal to a receiving end;
wherein: m is a positive integer and is more than or equal to 2; l is a positive integer and is more than or equal to 2.
In the FMT-based multi-carrier modulation and demodulation method of the ship VDES system, the receiving end receives a signal from the transmitting end, and performs FMT demodulation on the signal to obtain M paths of subcarrier baseband data, and the specific implementation method includes the following steps:
performing down-conversion processing on a radio frequency signal received by a receiving end to obtain an intermediate frequency signal; carrying out quadrature demodulation on the intermediate frequency signal to obtain a path of serial baseband signal;
converting the one path of serial baseband signal into M paths of parallel-transmission baseband signals; carrying out rate reduction on the M paths of baseband signals transmitted in parallel to obtain M paths of parallel down-sampling signals;
filtering the M paths of parallel down-sampled signals by adopting a matched filter group to obtain M matched filter signals, wherein the matched filter group comprises M matched filters, each matched filter comprises L filter coefficients, and the ith filter coefficient of the mth matched filter is represented as gm+M×lM is more than or equal to 0 and less than or equal to M-1, L is more than or equal to 0 and less than or equal to L-1, namely L filter coefficients G of the mth matched filtermExpressed as: gm＝{gm；gm+M；gm+M×2；…；gm+M×(L-1)}；
And after the M matched filtering signals are subjected to M-point FFT (fast Fourier transform), M paths of effective data recovered by a receiving end are obtained, and the M paths of effective data are M paths of subcarrier baseband data.
In the FMT-based multi-carrier modulation and demodulation method of the ship VDES system, each filter comprises L filter coefficients, the L filter coefficients are extracted from M multiplied by L order filter coefficients at equal intervals, the extraction interval is M-1, and F is obtainedm＝{fm；fm+M；fm+M×2；…；fm+M×(L-1)}。
In the FMT-based multi-carrier modulation and demodulation method of the ship VDES system, M paths of parallel sub-carrier signals am(n) obtaining M paths of parallel transform domain signals p after M-point IFFT processingm(n), the specific expression is as follows:
pm(n)＝IFFT[am(n)]
wherein: m represents the number of subcarriers of the VDES system of the vessel based on FMT;
using filter group to parallel said M paths of transform domain signals pm(n) performing filtering processing to obtain M filtering signals cm(n), the specific expression is as follows:
cm(n)＝pm(n)·Fm。
in the FMT-based multi-carrier modulation and demodulation method of the ship VDES system, M filtering signals are subjected to rate increase to obtain M paths of parallel up-sampling signals, and the carrier interval delta f of two adjacent signals in the M paths of parallel up-sampling signalsbIncrease, Δ fbThe specific expression of (a) is as follows:
Δfb＝TΔfa
wherein: Δ faIs the subcarrier signal interval, T is the rate boost coefficient; wherein Δ fa＝Ra，RaIs the signal transmission rate on the sub-carriers.
In the FMT-based multi-carrier modulation and demodulation method of the ship VDES system, each matched filter comprises L filter coefficients, the L filter coefficients are extracted from M multiplied by L filter coefficients at equal intervals, the extraction interval is M-1, and G is obtainedm＝{gm；gm+M；gm+M×2；…；gm+M×(L-1)}。
In the FMT-based multi-carrier modulation and demodulation method of the ship VDES system, M paths of parallel transmitted baseband signals are subjected to rate reduction to obtain M paths of parallel down-sampled signals, and the carrier interval delta f of two adjacent signals in the M paths of parallel down-sampled signalscDecrease, Δ fcThe specific expression of (a) is as follows:
Δfc＝Δfb/T'＝Δfa
wherein: Δ fbThe carrier interval of two adjacent signals in the up-sampled signals; t' is a rate reduction coefficient; Δ faIs the subcarrier signal spacing.
In the FMT-based multi-carrier modulation and demodulation method of the marine VDES system, the matched filter group is adopted to combine the M parallel down-sampled signals c'm(n) performing filtering processing to obtain M matched filtering signals p'm(n), the specific expression is as follows:
p′m(n)＝c′m(n)·Gm；
the M matched filtering signals p'm(n) obtaining M paths of effective data z recovered by the receiving end after the M-point FFT processingm(n), the specific expression is as follows:
zm(n)＝FFT[p′m(n)]。
an FMT-based multi-carrier modulation and demodulation system of a ship VDES system comprises an FMT multi-carrier modulation module and an FMT multi-carrier demodulation module, wherein:
FMT multi-carrier modulation module: performing M-point IFFT processing on the M paths of parallel subcarrier signals to obtain M paths of parallel transform domain signals; and filtering the M paths of parallel transform domain signals by adopting a sending filter bank to obtain M filtered signals, wherein the sending filter bank comprises M filters, each filter comprises L filter coefficients, and the ith filter coefficient of the mth filter is represented as fm+M×lM is more than or equal to 0 and less than or equal to M-1, L is more than or equal to 0 and less than or equal to L-1, namely L filter coefficients F of the mth filtermExpressed as: fm＝{fm；fm+M；fm+M×2；…；fm+M×(L-1)}; carrying out rate promotion on the M filtering signals to obtain M paths of parallel up-sampling signals, and converting the M paths of parallel up-sampling signals into a path of serial baseband signal; performing quadrature modulation on the path of serial baseband signal to obtain an intermediate frequency signal, performing up-conversion on the intermediate frequency signal to obtain a radio frequency signal, and sending the radio frequency signal to a receiving end;
FMT multi-carrier demodulation module: performing down-conversion processing on a radio frequency signal received by a receiving end to obtain an intermediate frequency signal, and performing quadrature demodulation on the intermediate frequency signal to obtain a path of serial baseband signal; converting the one path of serial baseband signal into M paths of parallel-transmission baseband signals; carrying out rate reduction on M paths of baseband signals transmitted in parallel to obtain M paths of parallel down-sampling signals; and filtering the M paths of parallel down-sampled signals by adopting a matched filter bank to obtain M matched filter signals, wherein the matched filter bank comprises M matched filters, each matched filter comprises L filter coefficients, and the ith filter coefficient of the mth matched filter is represented as gm+M×lM is more than or equal to 0 and less than or equal to M-1, L is more than or equal to 0 and less than or equal to L-1, namely L filter coefficients G of the mth matched filtermExpressed as: gm＝{gm；gm+M；gm+M×2；…；gm+M×(L-1)}; and after the M matched filtering signals are subjected to M-point FFT (fast Fourier transform), M paths of effective data recovered by a receiving end are obtained, and the M paths of effective data are M paths of subcarrier baseband data.
In the FMT-based multi-carrier modulation and demodulation system of the marine VDES system, the FMT multi-carrier modulation module comprises an IFFT module, a sending filter bank, an up-sampling module, a parallel-serial converter, an intermediate frequency modulator and an up-converter; wherein:
an IFFT module: m paths of parallel subcarrier signals are subjected to M-point IFFT processing to obtain M paths of parallel transform domain signals, and the M paths of parallel transform domain signals are sent to a sending filter bank;
a transmitting filter bank: receiving the M paths of parallel transform domain signals from an IFFT module, filtering the M paths of parallel transform domain signals to obtain M filtered signals, and sending the M filtered signals to an up-sampling module (4); wherein the transmit filter bank comprises M filters, each filter packetL filter coefficients, where the ith filter coefficient of the mth filter is denoted as fm+M×lM is more than or equal to 0 and less than or equal to M-1, L is more than or equal to 0 and less than or equal to L-1, namely L filter coefficients F of the mth filtermExpressed as: fm＝{fm；fm+M；fm+M×2；…；fm+M×(L-1)}；
An up-sampling module: receiving the M filtering signals from a sending filter bank, carrying out rate promotion on the M filtering signals to obtain M paths of parallel up-sampling signals, and sending the M paths of parallel up-sampling signals to a parallel-serial converter;
a parallel-to-serial converter: receiving the M paths of parallel up-sampling signals from an up-sampling module, converting the M paths of parallel up-sampling signals into a path of serial baseband signals, and sending the path of serial baseband signals to an intermediate frequency modulator;
an intermediate frequency modulator: receiving the one path of serial baseband signal from the parallel-to-serial converter, carrying out quadrature modulation on the serial baseband signal to obtain an intermediate frequency signal, and sending the intermediate frequency signal to an up-converter;
an up converter: and receiving the intermediate frequency signal from the intermediate frequency modulator, carrying out up-conversion on the intermediate frequency signal to obtain a radio frequency signal, and sending the radio frequency signal to a receiving end.
In the FMT-based multi-carrier modulation and demodulation system of the marine VDES system, the FMT multi-carrier demodulation module comprises an FFT module, a matched filter bank, a down-sampling module, a serial-parallel converter, an intermediate frequency demodulator and a down-converter; wherein:
a down converter: performing down-conversion processing on a radio frequency signal received by a receiving end to obtain an intermediate frequency signal, and sending the intermediate frequency signal to an intermediate frequency demodulator;
an intermediate frequency demodulator: receiving the intermediate frequency signal from a down converter, carrying out orthogonal demodulation on the intermediate frequency signal to obtain a path of serial baseband signal, and sending the serial baseband signal to a serial-to-parallel converter;
a serial-to-parallel converter: receiving the serial baseband signal from an intermediate frequency demodulator, converting the serial baseband signal into M paths of baseband signals transmitted in parallel, and sending the baseband signals to a down-sampling module;
a down-sampling module: receiving the M paths of parallel transmission baseband signals from a serial-parallel converter, reducing the rate of the M paths of parallel transmission baseband signals to obtain M paths of parallel down-sampling signals, and sending the M paths of parallel down-sampling signals to a matched filter bank;
matching the filter bank: receiving M paths of parallel down-sampling signals from a down-sampling module, filtering the M paths of parallel down-sampling signals to obtain M matched filtering signals, and sending the M matched filtering signals to an FFT module; wherein the matched filter bank comprises M matched filters, each matched filter comprising L filter coefficients, wherein the ith filter coefficient of the mth matched filter is represented as gm+M×lM is more than or equal to 0 and less than or equal to M-1, L is more than or equal to 0 and less than or equal to L-1, namely L filter coefficients G of the mth matched filtermExpressed as: gm＝{gm；gm+M；gm+M×2；…；gm+M×(L-1)}；
An FFT module: and receiving the M matched filtering signals from the matched filter bank, and performing M-point FFT processing on the M matched filtering signals to obtain M paths of effective data recovered by a receiving end, namely M paths of subcarrier baseband data.
Compared with the prior art, the invention has the beneficial effects that:
(1) the FMT-based multi-carrier modulation and demodulation method provided by the invention is realized in a digital domain, and has the advantages of stable structure and high reliability; the filter coefficient of the filter is reasonably selected, a strict filter bank is adopted among each subcarrier, the resource consumption is reduced, the processing method is simpler and easy to realize, the subcarriers are not mixed in the frequency domain, the ICI caused by the non-orthogonality of the subcarriers is avoided, and the realization complexity of the filter is reduced;
(2) the invention adopts Inverse Fast Fourier Transform (IFFT) and Fast Fourier Transform (FFT) modes to replace the modulation and demodulation parts of each subcarrier, simplifies the system structure, reduces the realization complexity of the multi-carrier modulation and demodulation system, and solves the problems of resource shortage and high realization complexity caused by a plurality of groups of intermediate frequency modulators and intermediate frequency demodulators.
(3) The invention is realized based on a full digital architecture, has the advantages of stable structure, high reliability, flexible use and the like, does not need to change hardware equipment, can cover the application requirements of various modulation systems and various code rates only by respectively configuring software parameters, and reduces the cost.
(4) The invention adopts a filtering multi-tone modulation method, can strictly limit the spectrum bandwidth of each subcarrier, reduces the influence of frequency deviation brought by the time-varying characteristic of a wireless channel and the inherent frequency deviation between the carrier frequencies at the transmitting end and the receiving end on the orthogonality among the subcarriers, and improves the system performance; meanwhile, M items of grouping are carried out on the narrow-band filter by adopting an MxL order multi-tone filter group, the length of the filter on each subcarrier is reduced to 1/M of the original length, and the implementation complexity of the filter is reduced.
Drawings
FIG. 1 is a simplified model diagram of the signal transmission link of the VDES system of the FMT-based ship of the present invention;
fig. 2 is a block diagram of an embodiment of the FMT-based multi-carrier modem system of the present invention.
Detailed Description
The invention is described in further detail below with reference to the following figures and specific examples:
fig. 1 is a simplified model diagram of a signal transmission link of a FMT-based marine VDES system according to the present invention, and fig. 2 is a block diagram of an embodiment of a FMT-based multi-carrier modem system according to the present invention. The FMT-based multi-carrier modulation and demodulation system of the ship VDES system comprises an FMT multi-carrier modulation module and an FMT multi-carrier demodulation module, wherein the FMT multi-carrier modulation module comprises an IFFT module 2, a sending filter bank 3, an up-sampling module 4, a parallel-serial converter 5, an intermediate frequency modulator 6 and an up-converter 7. At the transmitting end, the output signal of the IFFT block 2 is connected to a transmit filter bank 3; the output signal of the sending filter bank 3 is connected to the upper sampling module 4; the output signal of the up-sampling module 4 is connected to the parallel-to-serial converter 5; the output signal of the parallel-serial converter 5 is connected to the intermediate frequency modulator 6; the output signal of the intermediate frequency modulator 6 is connected to an upper frequency converter 7; the output signal of the up-converter 7 is sent to the receiving end.
The FMT multi-carrier demodulation module comprises an FFT module 15, a matched filter bank 14, a down-sampling module 13, a serial-to-parallel converter 12, an intermediate frequency demodulator 11 and a down-converter 10. At the receiving end, the output signal of the down-converter 10 is connected to an intermediate frequency demodulator 11; the output signal of the intermediate frequency demodulator 11 is connected to a serial-to-parallel converter 12; the output signal of the serial-to-parallel converter 12 is connected to a down-sampling module 13; the output signal of the down-sampling module 13 is connected to a matched filter bank 14; the output signal of the matched filter bank 14 is connected to an FFT module 15. The specific functions of each module are as follows:
the IFFT module 2: combining M paths of parallel subcarrier signals am(n) obtaining M paths of parallel transform domain signals p after M-point IFFT processingm(n) and sent to the transmit filter bank 3. The specific expression is as follows:
pm(n)＝IFFT[am(n)]
wherein: m represents the number of subcarriers of a ship VDES system based on FMT, and the signal transmission rate on each subcarrier is RaSubcarrier spacing of Δ fa＝Ra。
Transmission filter bank 3: receiving the M paths of parallel transform domain signals p from the IFFT module 2m(n) for the M parallel transform domain signals pm(n) filtering to obtain M narrow-band filtering signals cm(n), send to the up-sampling module 4; wherein the transmit filter bank comprises M filters, each filter comprising L filter coefficients, wherein the ith filter coefficient of the mth filter is represented as fm+M×lM is more than or equal to 0 and less than or equal to M-1, L is more than or equal to 0 and less than or equal to L-1, namely L filter coefficients F of the mth filtermExpressed as: fm＝{fm；fm+M；fm+M×2；…；fm+M×(L-1)}。
Each filter comprises L filter coefficients, the L filter coefficients are obtained by extraction at equal intervals from M multiplied by L filter coefficients, the extraction interval is M-1, and F is obtainedm＝{fm；fm+M；fm+M×2；…；fm+M×(L-1)}。
M narrow-band filtered signals cm(n) the expression is:
cm(n)＝pm(n)·Fm
wherein: MxL order transmit filter bank is divided into MGroups of parallel transform domain signals p respectively corresponding to the M pathsm(n)。
The up-sampling module 4: receiving said M narrowband filtered signals c from the transmit filter bank 3m(n) filtering the M filtered signals cm(n) carrying out rate promotion to obtain M paths of parallel up-sampling signals dm(k) And sent to the parallel-to-serial converter 5.
The carrier interval delta f of two adjacent signals in the M paths of parallel up-sampling signalsbIncrease, Δ fbThe specific expression of (a) is as follows:
Δfb＝TΔfa
wherein: Δ faIs the subcarrier signal interval, T is the rate boost coefficient; wherein Δ fa＝Ra，RaIs the signal transmission rate on the sub-carriers.
Parallel-to-serial converter 5: receiving said M parallel upsampled signals d from the upsampling module 4m(k) The M paths of parallel up-sampling signals dm(k) Converting the signal into a path of serial baseband signal q (k) and sending the signal to the intermediate frequency modulator 6;
the intermediate frequency modulator 6: receiving the one-path serial baseband signal q (k) from the parallel-to-serial converter 5, performing quadrature modulation on the serial baseband signal q (k) to obtain an intermediate frequency signal x (k), and sending the intermediate frequency signal x (k) to the up-converter 7; the center frequency of the modulated intermediate frequency signal x (k) is omegaI。
The up-converter 7: receiving the intermediate frequency signal x (k) from the intermediate frequency modulator 6, performing up-conversion on the intermediate frequency signal x (k) to obtain a radio frequency signal s (k), and transmitting the radio frequency signal s (k) to a receiving end; the radio-frequency signal s (k) has a center frequency of ωS。
Down-converter 10: the center frequency received by a receiving end is omegaSThe radio frequency signal s (k) is down-converted to obtain an intermediate frequency signal y (k), and the intermediate frequency signal y (k) is sent to an intermediate frequency demodulator 11; the center frequency of the intermediate frequency signal y (k) is omegaI。
Intermediate frequency demodulator 11: receiving the intermediate frequency signal y (k) from the down converter 10, performing quadrature demodulation on the intermediate frequency signal y (k) to obtain a channel of serial baseband signal q '(k), and sending the channel of serial baseband signal q' (k) to the serial-to-parallel converter 12;
serial-to-parallel converter 12: the serial baseband signal q '(k) is received from the intermediate frequency demodulator 11, and converted into an M-channel parallel-transmitted baseband signal d'm(k) And sends the data to the down-sampling module 13;
the down-sampling module 13: receiving the M-lane parallel transmitted baseband signal d 'from the serial-to-parallel converter 12'm(k) The M paths of baseband signals d 'transmitted in parallel'm(k) Carrying out rate reduction to obtain M-channel parallel down-sampling signals c'm(n) to the matched filter bank 14. The carrier interval delta f of two adjacent signals in the M paths of parallel down-sampling signalscReducing, the transmission rate of each path of signal after down sampling is RcWherein: rc＝Rb/T'＝RaWhen the subcarrier spacing is reduced, Δ fcThe specific expression of (a) is as follows:
Δfc＝Rc＝Δfb/T'＝Δfa
wherein: Δ fbThe carrier interval of two adjacent signals in the up-sampled signals; t' is a rate reduction coefficient; Δ faIs the subcarrier signal spacing.
At this time, the transmission rate and the subcarrier interval of each subcarrier signal are respectively the same as those of the transmitting end, and the down-sampled signal c'm(n) and transmitting end narrow-band filtering signal cm(n) are equal, as shown in the following equation:
c′m(n)＝cm(n)
matched filter bank 14: receiving M-channel parallel downsampled signal c 'from downsampling module 13'm(n) parallel down-sampling the M lines of signals c'm(n) performing filtering processing to obtain M matched filtering signals p'm(n), sent to the FFT module 15; wherein the matched filter bank comprises M matched filters, each matched filter comprising L filter coefficients, wherein the ith filter coefficient of the mth matched filter is represented as gm+M×lM is more than or equal to 0 and less than or equal to M-1, L is more than or equal to 0 and less than or equal to L-1, namely L filter coefficients G of the mth matched filtermExpressed as: gm＝{gm；gm+M；gm+M×2；…；gm+M×(L-1)}。
Each matched filter comprises L filter coefficients, the L filter coefficients are obtained by extracting the filter coefficients of M multiplied by L at equal intervals, the extraction interval is M-1, and G is obtainedm＝{gm；gm+M；gm+M×2；…；gm+M×(L-1)}。
Transform domain signal p'm(n) the expression is:
p′m(n)＝c′m(n)·Gm
wherein: the MxL-order multi-tone matched filter bank is divided into M groups of receiving end transform domain signals p 'corresponding to the M paths of paralleling respectively'm(n)。
The FFT module 15: receiving the M matched filtered signals p 'from matched filter bank 14'm(n), matching the M matched filtered signals p'm(n) obtaining M paths of effective data z recovered by the receiving end after the M-point FFT processingm(n) is M paths of subcarrier baseband data, thereby achieving the purpose of realizing multicarrier transmission without adopting multi-path intermediate frequency modulation and demodulation, and recovering M paths of effective data zmThe expression of (n) is:
zm(n)＝FFT[p′m(n)]
the invention relates to a multi-carrier modulation and demodulation method based on FMT for a ship VDES system, which comprises the steps that a sending end carries out FMT modulation on M paths of sub-carrier signals to obtain M paths of radio frequency signals, and a receiving end receives the signals from the sending end and carries out FMT demodulation on the signals to obtain M paths of sub-carrier baseband data.
Wherein: the specific implementation method for obtaining the M paths of radio frequency signals by the transmitting end through FMT modulation of the M paths of subcarrier signals comprises the following steps:
(1) m-channel parallel subcarrier signal am(n) obtaining M paths of parallel transform domain signals p after being processed by an M-point IFFT modulem(n) expressed as:
pm(n)＝IFFT[am(n)]
wherein: m represents the number of subcarriers of the VDES system of the vessel based on FMT, and each path of subcarriersSignal transmission rate on carrier wave is RaSubcarrier spacing of Δ fa＝Ra；
(2) Adopting M multiplied by L order multi-tone narrow-band transmission filter group to carry out parallel conversion domain signals p of the M pathsm(n) filtering to obtain M narrow-band filtering signals cm(n) the expression is:
cm(n)＝pm(n)·Fm
wherein: fmThe coefficient of the M multiplied by L order multi-tone narrow-band transmitting filter bank is represented, and the M multiplied by L order multi-tone narrow-band transmitting filter bank is divided into M groups of parallel transform domain signals p respectively corresponding to the M pathsm(n), wherein the transmit filter bank comprises M filters, each filter comprising L filter coefficients, wherein the ith filter coefficient of the mth filter is represented as fm+M×lM is more than or equal to 0 and less than or equal to M-1, L is more than or equal to 0 and less than or equal to L-1, namely L filter coefficients F of the mth filtermExpressed as: fm＝{fm；fm+M；fm+M×2；…；fm+M×(L-1)}。
(3) M narrow-band filtered signals cm(n) respectively carrying out rate promotion through the sampling module on the T point to obtain M-path sampling signals dm(k) Each path of signal transmission rate is RbWherein: rb＝TRaAt this time, the subcarrier spacing is increased as:
Δfb＝Rb＝TΔfa
(4) the parallel-serial converter up-samples M paths of parallel signals dm(k) Converting into a path of baseband signal q (k) transmitted in series;
(5) the intermediate frequency modulator carries out quadrature modulation on a path of baseband signal q (k) transmitted in series to obtain an intermediate frequency signal x (k), and the center frequency of the modulated intermediate frequency signal x (k) is omegaI；
(6) The up-converter up-converts the intermediate frequency modulation signal x (k) to obtain a radio frequency signal s (k) and sends the radio frequency signal s (k) to a receiving end; the center frequency of the up-converted radio frequency signal s (k) is omegaS. The expression of the rf transmission signal s (k) is:
wherein the meanings of the symbols are as follows:
am(n): m is more than or equal to 0 and less than or equal to M-1 of M subcarrier signals at a sending end;
IFFT [ ]: processing functions by an M-point IFFT module;
Fm: m is more than or equal to 0 and less than or equal to M-1;
P2S [. ]: a parallel-to-serial converter processing function;
ωI: the center frequency of the intermediate frequency modulator;
ωS: the operating frequency of the up-converter;
t: the number of sampling points of the up-sampling module;
m: the number of subcarriers of the ship VDES system.
The receiving end receives signals from the transmitting end and performs FMT demodulation on the signals to obtain M paths of subcarrier baseband data, and the specific implementation method comprises the following steps:
(7) the center frequency received by a receiving end is omegaSThe radio frequency signal s (k) is processed by down-conversion by a down converter to obtain a central frequency omegaIThe intermediate frequency signal y (k);
(8) the intermediate frequency demodulator carries out orthogonal demodulation on the intermediate frequency signal y (k) to obtain a path of serial baseband signal q' (k);
(9) the serial-to-parallel converter converts one path of serial baseband signal q '(k) into M paths of parallel-transmitted baseband signals d'm(k)；
(10) M-line parallel transmission baseband signal d'm(k) Respectively carrying out rate reduction through a T-point down-sampling module to obtain M-path down-sampling signals c'm(n), the transmission rate of each path of signals after down sampling is RcWherein: rc＝Rb/T'＝RaAt this point, the subcarrier spacing is reduced to:
Δfc＝Rc＝Δfb/T'＝Δfa
at this time, the transmission speed of each path of subcarrier signalThe rate and the subcarrier interval are respectively the same as those of the transmitting end, and a down-sampling signal c'm(n) and transmitting end narrow-band filtering signal cm(n) equal, as shown in equation (h);
c′m(n)＝cm(n)
(11) adopting an MxL-order polyphonic matched filter group to pair the M paths of parallel downsampled signals c'm(n) performing filtering processing to obtain a receiving-end transform domain signal p'm(n) the expression is:
p′m(n)＝c′m(n)·Gm
wherein: gmThe coefficient of the M multiplied by L order multi-tone matched filter bank is represented, and the M multiplied by L order multi-tone matched filter bank is divided into M groups of receiving end transform domain signals p 'corresponding to the M paths of parallel receiving end transform domain signals'm(n), each matched filter contains L filter coefficients, wherein the ith filter coefficient of the mth matched filter is represented as gm+M×lM is more than or equal to 0 and less than or equal to M-1, L is more than or equal to 0 and less than or equal to L-1, namely L filter coefficients G of the mth matched filtermExpressed as: gm＝{gm；gm+M；gm+M×2；…；gm+M×(L-1)}。
(12) Converting the receiving end into the domain signal p'm(n) after being processed by the M-point FFT module, M paths of effective data z recovered by the receiving end are finally obtainedm(n), thereby achieving the purpose of realizing multi-carrier transmission without adopting multi-path intermediate frequency modulation and demodulation, and recovering M paths of effective data zmThe expression of (n) is:
zm(n)＝FFT[p′m(n)]
wherein the meanings of the symbols are as follows:
FFT [ ]: processing a function by an M-point FFT module;
Gm: m is more than or equal to 0 and less than or equal to M-1;
S2P [ ]: a serial-to-parallel converter processing function;
ωI: the center frequency of the intermediate frequency demodulator;
ωS: the operating frequency of the down converter;
t': the number of sampling points of the down-sampling module;
m: the number of subcarriers of the ship VDES system.
The receiving end receives the radio frequency signal s (k), substitutes the formula (a) into the formula (b), and finally meets the requirement of the formula (c) by reasonably designing the filter coefficient and the number of sampling points.
zm(n)＝am(n),0≤m≤M-1 (c)
The multi-carrier modulation and demodulation method and the modulation and demodulation system based on FMT are realized in a digital domain, and have stable structure and high reliability; secondly, a strict multi-tone narrow-band filter bank is adopted among each subcarrier, so that the subcarriers are not subjected to aliasing in a frequency domain, ICI (inter-carrier interference) caused by subcarrier non-orthogonality is avoided, and meanwhile, the implementation complexity of the filter is reduced; in addition, the invention adopts Inverse Fast Fourier Transform (IFFT) and Fast Fourier Transform (FFT) modes to replace each subcarrier modulation and demodulation part, thereby simplifying the system structure and reducing the implementation complexity of the multicarrier modulation and demodulation system.
Example 1
In the embodiment, the data transmission rate on each sub-carrier of the FMT-based multi-carrier modulation and demodulation system is Ra2.4kbps, the number of subcarriers, the number of transform points of the IFFT module 2 and the FFT module 25 is M64, the number of upsampling points T2, the number of downsampling points T' 2, the filter bandwidths of the multi-tone narrowband transmitting filter bank 4 and the multi-tone matched filter bank 23 are B153.6 kHz, and the bandwidth of each subcarrier is BmThe bandwidth of the sub-carrier is equal to the data transmission rate of each path of sub-carrier, and the influence of ICI caused by non-orthogonality of the sub-carrier on the performance of the VDES system of the ship can be effectively reduced.
The performance and the implementation complexity of the multi-tone narrowband transmitting filter bank 4 and the multi-tone matching filter bank 23 are comprehensively considered, the order of each filter is M × L-256, and the filters are divided into M-64 groups, the order of each group of filters is L-4, if a traditional filter is adopted, 256 complex multipliers are needed for implementation, if the invention is adopted, 4 complex multipliers are needed to change the filter coefficients, so that the filtering function can be realized, and the FPGA resource is greatly reduced.
The center frequencies of the intermediate frequency modulator 10 and the intermediate frequency demodulator 17 are ωIAt 6.4MHz, the operating frequency of the up-converter 12 and down-converter 15 is ωS160 MHz. The actual transmitted subcarrier spacing is calculated according to the formula (f) as: Δ fb＝Rb＝TΔfa＝TRa＝4.8kHz。
If the orthogonal modulation and demodulation is realized by adopting the parallel intermediate frequency modulator and the intermediate frequency demodulator, 64 intermediate frequency modulators are needed to be adopted at the sending end, and 64 intermediate frequency demodulators are needed to be adopted at the receiving end, so that a large amount of FPGA resources are consumed. If the invention is adopted, the FMT modulation is realized through the IFFT module 2 at the sending end, and the FMT demodulation is realized through the FFT module 23 at the receiving end, the intermediate frequency orthogonal modulation and demodulation can be realized only by adopting 1 intermediate frequency modulator and 1 intermediate frequency demodulator, thereby greatly reducing the realization complexity of the multi-carrier modulation and demodulation system.
In this embodiment, the IFFT at the transmitting end and the FFT at the receiving end can ensure that 64 subcarriers in the transformation process are completely orthogonal, and data transmission is performed at a rate of 2.4kbps on each subcarrier at a subcarrier interval of 4.8kHz, thereby effectively reducing the impact of ICI caused by subcarrier non-orthogonality on the performance of the VDES system for a ship.
The above description is only one embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
The invention has not been described in detail in part of the common general knowledge of those skilled in the art.
Claims (10)
1. The FMT-based multi-carrier modulation and demodulation method of the ship VDES system is characterized by comprising the following steps: the method comprises the steps that a sending end carries out FMT modulation on M paths of subcarrier signals to obtain M paths of radio frequency signals, and the M paths of radio frequency signals are sent to a receiving end, and the specific implementation method comprises the following steps:
m paths of parallel subcarrier signals are subjected to M-point IFFT processing to obtain M paths of parallel transform domain signals;
and filtering the M paths of parallel transform domain signals by adopting a sending filter bank to obtain M filtered signals, wherein the sending filter bank comprises M filters, each filter comprises L filter coefficients, and the ith filter coefficient of the mth filter is represented as fm+M×lM is more than or equal to 0 and less than or equal to M-1, L is more than or equal to 0 and less than or equal to L-1, namely L filter coefficients F of the mth filtermExpressed as: fm＝{fm；fm+M；fm+M×2；…；fm+M×(L-1)}；
Carrying out rate promotion on the M filtering signals to obtain M paths of parallel up-sampling signals, and converting the M paths of parallel up-sampling signals into a path of serial baseband signal;
performing quadrature modulation on the path of serial baseband signal to obtain an intermediate frequency signal; carrying out up-conversion on the intermediate frequency signal to obtain a radio frequency signal, and sending the radio frequency signal to a receiving end;
wherein: m is a positive integer and is more than or equal to 2; l is a positive integer and is more than or equal to 2;
the method comprises the following steps that a receiving end receives signals from a transmitting end, FMT demodulation is carried out on the signals, and M paths of subcarrier baseband data are obtained, and the specific implementation method comprises the following steps:
performing down-conversion processing on a radio frequency signal received by a receiving end to obtain an intermediate frequency signal; carrying out quadrature demodulation on the intermediate frequency signal to obtain a path of serial baseband signal;
converting the one path of serial baseband signal into M paths of parallel-transmission baseband signals; carrying out rate reduction on the M paths of baseband signals transmitted in parallel to obtain M paths of parallel down-sampling signals;
filtering the M paths of parallel down-sampling signals by adopting a matched filter group to obtain M matched filtering signals, wherein the matched filter group comprises M matched filtersEach matched filter comprises L filter coefficients, wherein the ith filter coefficient of the mth matched filter is represented as gm+M×lM is more than or equal to 0 and less than or equal to M-1, L is more than or equal to 0 and less than or equal to L-1, namely L filter coefficients G of the mth matched filtermExpressed as: gm＝{gm；gm+M；gm+M×2；…；gm+M×(L-1)}；
After the M matched filtering signals are subjected to M-point FFT processing, M paths of effective data recovered by a receiving end are obtained, and the M paths of effective data are M paths of subcarrier baseband data;
wherein: the specific implementation method for obtaining the M paths of radio frequency signals by the transmitting end through FMT modulation of the M paths of subcarrier signals comprises the following steps:
(1) m-channel parallel subcarrier signal am(n) obtaining M paths of parallel transform domain signals p after being processed by an M-point IFFT modulem(n) expressed as:
pm(n)＝IFFT[am(n)]
wherein: m represents the number of subcarriers of a ship VDES system based on FMT, and the signal transmission rate on each subcarrier is RaSubcarrier spacing of Δ fa＝Ra；
(2) Adopting M multiplied by L order multi-tone narrow-band transmission filter group to carry out parallel conversion domain signals p of the M pathsm(n) filtering to obtain M narrow-band filtering signals cm(n) the expression is:
cm(n)＝pm(n)·Fm
wherein: fmThe coefficient of the M multiplied by L order multi-tone narrow-band transmitting filter bank is represented, and the M multiplied by L order multi-tone narrow-band transmitting filter bank is divided into M groups of parallel transform domain signals p respectively corresponding to the M pathsm(n), wherein the transmit filter bank comprises M filters, each filter comprising L filter coefficients, wherein the ith filter coefficient of the mth filter is represented as fm+M×lM is more than or equal to 0 and less than or equal to M-1, L is more than or equal to 0 and less than or equal to L-1, namely L filter coefficients F of the mth filtermExpressed as: fm＝{fm；fm+M；fm+M×2；…；fm+M×(L-1)}；
(3) M number of narrow band filteringSignal cm(n) respectively carrying out rate promotion through the sampling module on the T point to obtain M-path sampling signals dm(k) Each path of signal transmission rate is RbWherein: rb＝TRaAt this time, the subcarrier spacing is increased as:
Δfb＝Rb＝TΔfa
(4) the parallel-serial converter up-samples M paths of parallel signals dm(k) Converting into a path of baseband signal q (k) transmitted in series;
(5) the intermediate frequency modulator carries out quadrature modulation on a path of baseband signal q (k) transmitted in series to obtain an intermediate frequency signal x (k), and the center frequency of the modulated intermediate frequency signal x (k) is omegaI；
(6) The up-converter up-converts the intermediate frequency modulation signal x (k) to obtain a radio frequency signal s (k) and sends the radio frequency signal s (k) to a receiving end; the center frequency of the up-converted radio frequency signal s (k) is omegaS(ii) a The expression of the rf transmission signal s (k) is:
wherein the meanings of the symbols are as follows:
am(n): m is more than or equal to 0 and less than or equal to M-1 of M subcarrier signals at a sending end;
IFFT [ ]: processing functions by an M-point IFFT module;
Fm: m is more than or equal to 0 and less than or equal to M-1;
P2S [. ]: a parallel-to-serial converter processing function;
ωI: the center frequency of the intermediate frequency modulator;
ωS: the operating frequency of the up-converter;
t: the number of sampling points of the up-sampling module;
m: the number of subcarriers of the ship VDES system;
the receiving end receives signals from the transmitting end and performs FMT demodulation on the signals to obtain M paths of subcarrier baseband data, and the specific implementation method comprises the following steps:
(7) the center frequency received by a receiving end is omegaSThe radio frequency signal s (k) is processed by down-conversion by a down converter to obtain a central frequency omegaIThe intermediate frequency signal y (k);
(8) the intermediate frequency demodulator carries out orthogonal demodulation on the intermediate frequency signal y (k) to obtain a path of serial baseband signal q' (k);
(9) the serial-to-parallel converter converts one path of serial baseband signal q '(k) into M paths of parallel-transmitted baseband signals d'm(k)；
(10) M-line parallel transmission baseband signal d'm(k) Respectively carrying out rate reduction through a T-point down-sampling module to obtain M-path down-sampling signals c'm(n), the transmission rate of each path of signals after down sampling is RcWherein: rc＝Rb/T'＝RaAt this point, the subcarrier spacing is reduced to:
Δfc＝Rc＝Δfb/T'＝Δfa
at this time, the transmission rate and the subcarrier interval of each subcarrier signal are respectively the same as those of the transmitting end, and the down-sampled signal c'm(n) and transmitting end narrow-band filtering signal cm(n) equal, as shown in the following equation;
c′m(n)＝cm(n)
(11) adopting an MxL-order polyphonic matched filter group to pair the M paths of parallel downsampled signals c'm(n) performing filtering processing to obtain a receiving-end transform domain signal p'm(n) the expression is:
p′m(n)＝c′m(n)·Gm
wherein: gmThe coefficient of the M multiplied by L order multi-tone matched filter bank is represented, and the M multiplied by L order multi-tone matched filter bank is divided into M groups of receiving end transform domain signals p 'corresponding to the M paths of parallel receiving end transform domain signals'm(n), each matched filter contains L filter coefficients, wherein the ith filter coefficient of the mth matched filter is represented as gm+M×lM is more than or equal to 0 and less than or equal to M-1, L is more than or equal to 0 and less than or equal to L-1, namely L filter coefficients G of the mth matched filtermExpressed as: gm＝{gm；gm+M；gm+M×2；…；gm+M×(L-1)}；
(12) Converting the receiving end into the domain signal p'm(n) after being processed by the M-point FFT module, M paths of effective data z recovered by the receiving end are finally obtainedm(n), thereby achieving the purpose of realizing multi-carrier transmission without adopting multi-path intermediate frequency modulation and demodulation, and recovering M paths of effective data zmThe expression of (n) is:
zm(n)＝FFT[p′m(n)]
wherein the meanings of the symbols are as follows:
FFT [ ]: processing a function by an M-point FFT module;
Gm: m is more than or equal to 0 and less than or equal to M-1;
S2P [ ]: a serial-to-parallel converter processing function;
ωI: the center frequency of the intermediate frequency demodulator;
ωS: the operating frequency of the down converter;
t': the number of sampling points of the down-sampling module;
m: the number of subcarriers of the ship VDES system;
a receiving end receives a radio frequency signal s (k), substitutes the formula (a) into the formula (b) and meets the requirement of the following formula (c);
zm(n)＝am(n),0≤m≤M-1 (c)。
2. the FMT-based multi-carrier modulation and demodulation method for marine VDES system of claim 1, wherein: each filter comprises L filter coefficients, the L filter coefficients are obtained by extraction at equal intervals from M multiplied by L filter coefficients, the extraction interval is M-1, and F is obtainedm＝{fm；fm+M；fm+M×2；…；fm+M×(L-1)}。
3. The method of claim 1The FMT-based multi-carrier modulation and demodulation method of the ship VDES system is characterized by comprising the following steps: m-channel parallel subcarrier signal am(n) obtaining M paths of parallel transform domain signals p after M-point IFFT processingm(n), the specific expression is as follows:
pm(n)＝IFFT[am(n)]
wherein: m represents the number of subcarriers of the VDES system of the vessel based on FMT;
using filter group to parallel said M paths of transform domain signals pm(n) performing filtering processing to obtain M filtering signals cm(n), the specific expression is as follows:
cm(n)＝pm(n)·Fm。
4. an FMT-based multi-carrier modulation and demodulation method for marine VDES system according to any one of claims 1-3, wherein: carrying out rate promotion on the M filtering signals to obtain M paths of parallel up-sampling signals, wherein the carrier wave interval delta f of two adjacent signals in the M paths of parallel up-sampling signalsbIncrease, Δ fbThe specific expression of (a) is as follows:
Δfb＝TΔfa
wherein: Δ faIs the subcarrier signal interval, T is the rate boost coefficient; wherein Δ fa＝Ra，RaIs the signal transmission rate on the sub-carriers.
5. The FMT-based multi-carrier modulation and demodulation method for marine VDES system of claim 1, wherein: each matched filter comprises L filter coefficients, the L filter coefficients are obtained by extracting the filter coefficients of M multiplied by L at equal intervals, the extraction interval is M-1, and G is obtainedm＝{gm；gm+M；gm+M×2；…；gm+M×(L-1)}。
6. An FMT-based multi-carrier modulation and demodulation method for marine VDES system according to claim 1 or 5, characterized in that: reducing the speed of M paths of parallel transmitted baseband signals to obtain M paths of parallel transmitted baseband signalsA line down-sampled signal, the carrier spacing Δ f of two adjacent signals in the M parallel down-sampled signalscDecrease, Δ fcThe specific expression of (a) is as follows:
Δfc＝Δfb/T'＝Δfa
wherein: Δ fbThe carrier interval of two adjacent signals in the up-sampled signals; t' is a rate reduction coefficient; Δ faIs the subcarrier signal spacing.
7. The FMT-based multi-carrier modulation and demodulation method for marine VDES system of claim 1, wherein: adopting matched filter group to carry out parallel down-sampling on the M lines of signals c'm(n) performing filtering processing to obtain M matched filtering signals p'm(n), the specific expression is as follows:
p′m(n)＝c′m(n)·Gm；
the M matched filtering signals p'm(n) obtaining M paths of effective data z recovered by the receiving end after the M-point FFT processingm(n), the specific expression is as follows:
zm(n)＝FFT[p′m(n)]。
8. an FMT-based multi-carrier modulation and demodulation system of a ship VDES system is characterized in that: the FMT multi-carrier modulation and demodulation system comprises an FMT multi-carrier modulation module and an FMT multi-carrier demodulation module, wherein:
FMT multi-carrier modulation module: performing M-point IFFT processing on the M paths of parallel subcarrier signals to obtain M paths of parallel transform domain signals; and filtering the M paths of parallel transform domain signals by adopting a sending filter bank to obtain M filtered signals, wherein the sending filter bank comprises M filters, each filter comprises L filter coefficients, and the ith filter coefficient of the mth filter is represented as fm+M×lM is more than or equal to 0 and less than or equal to M-1, L is more than or equal to 0 and less than or equal to L-1, namely L filter coefficients F of the mth filtermExpressed as: fm＝{fm；fm+M；fm+M×2；…；fm+M×(L-1)}; rate the M filtered signalsPromoting to obtain M paths of parallel up-sampling signals, and converting the M paths of parallel up-sampling signals into a path of serial baseband signals; performing quadrature modulation on the path of serial baseband signal to obtain an intermediate frequency signal, performing up-conversion on the intermediate frequency signal to obtain a radio frequency signal, and sending the radio frequency signal to a receiving end;
FMT multi-carrier demodulation module: performing down-conversion processing on a radio frequency signal received by a receiving end to obtain an intermediate frequency signal, and performing quadrature demodulation on the intermediate frequency signal to obtain a path of serial baseband signal; converting the one path of serial baseband signal into M paths of parallel-transmission baseband signals; carrying out rate reduction on M paths of baseband signals transmitted in parallel to obtain M paths of parallel down-sampling signals; and filtering the M paths of parallel down-sampled signals by adopting a matched filter bank to obtain M matched filter signals, wherein the matched filter bank comprises M matched filters, each matched filter comprises L filter coefficients, and the ith filter coefficient of the mth matched filter is represented as gm+M×lM is more than or equal to 0 and less than or equal to M-1, L is more than or equal to 0 and less than or equal to L-1, namely L filter coefficients G of the mth matched filtermExpressed as: gm＝{gm；gm+M；gm+M×2；…；gm+M×(L-1)}; after the M matched filtering signals are subjected to M-point FFT processing, M paths of effective data recovered by a receiving end are obtained, and the M paths of effective data are M paths of subcarrier baseband data;
wherein: the specific implementation method for obtaining the M paths of radio frequency signals by the transmitting end through FMT modulation of the M paths of subcarrier signals comprises the following steps:
(1) m-channel parallel subcarrier signal am(n) obtaining M paths of parallel transform domain signals p after being processed by an M-point IFFT modulem(n) expressed as:
pm(n)＝IFFT[am(n)]
wherein: m represents the number of subcarriers of a ship VDES system based on FMT, and the signal transmission rate on each subcarrier is RaSubcarrier spacing of Δ fa＝Ra；
(2) Adopting M multiplied by L order multi-tone narrow-band transmission filter group to carry out parallel conversion domain signals p of the M pathsm(n) performing a filtering processObtaining M narrow-band filtering signals cm(n) the expression is:
cm(n)＝pm(n)·Fm
wherein: fmThe coefficient of the M multiplied by L order multi-tone narrow-band transmitting filter bank is represented, and the M multiplied by L order multi-tone narrow-band transmitting filter bank is divided into M groups of parallel transform domain signals p respectively corresponding to the M pathsm(n), wherein the transmit filter bank comprises M filters, each filter comprising L filter coefficients, wherein the ith filter coefficient of the mth filter is represented as fm+M×lM is more than or equal to 0 and less than or equal to M-1, L is more than or equal to 0 and less than or equal to L-1, namely L filter coefficients F of the mth filtermExpressed as: fm＝{fm；fm+M；fm+M×2；…；fm+M×(L-1)}；
(3) M narrow-band filtered signals cm(n) respectively carrying out rate promotion through the sampling module on the T point to obtain M-path sampling signals dm(k) Each path of signal transmission rate is RbWherein: rb＝TRaAt this time, the subcarrier spacing is increased as:
Δfb＝Rb＝TΔfa
(4) the parallel-serial converter up-samples M paths of parallel signals dm(k) Converting into a path of baseband signal q (k) transmitted in series;
(5) the intermediate frequency modulator carries out quadrature modulation on a path of baseband signal q (k) transmitted in series to obtain an intermediate frequency signal x (k), and the center frequency of the modulated intermediate frequency signal x (k) is omegaI；
(6) The up-converter up-converts the intermediate frequency modulation signal x (k) to obtain a radio frequency signal s (k) and sends the radio frequency signal s (k) to a receiving end; the center frequency of the up-converted radio frequency signal s (k) is omegaS(ii) a The expression of the rf transmission signal s (k) is:
wherein the meanings of the symbols are as follows:
am(n): m-path subcarrier at sending endSignal, M is more than or equal to 0 and less than or equal to M-1;
IFFT [ ]: processing functions by an M-point IFFT module;
Fm: m is more than or equal to 0 and less than or equal to M-1;
P2S [. ]: a parallel-to-serial converter processing function;
ωI: the center frequency of the intermediate frequency modulator;
ωS: the operating frequency of the up-converter;
t: the number of sampling points of the up-sampling module;
m: the number of subcarriers of the ship VDES system;
the receiving end receives signals from the transmitting end and performs FMT demodulation on the signals to obtain M paths of subcarrier baseband data, and the specific implementation method comprises the following steps:
(7) the center frequency received by a receiving end is omegaSThe radio frequency signal s (k) is processed by down-conversion by a down converter to obtain a central frequency omegaIThe intermediate frequency signal y (k);
(8) the intermediate frequency demodulator carries out orthogonal demodulation on the intermediate frequency signal y (k) to obtain a path of serial baseband signal q' (k);
(9) the serial-to-parallel converter converts one path of serial baseband signal q '(k) into M paths of parallel-transmitted baseband signals d'm(k)；
(10) M-line parallel transmission baseband signal d'm(k) Respectively carrying out rate reduction through a T-point down-sampling module to obtain M-path down-sampling signals c'm(n), the transmission rate of each path of signals after down sampling is RcWherein: rc＝Rb/T'＝RaAt this point, the subcarrier spacing is reduced to:
Δfc＝Rc＝Δfb/T'＝Δfa
at this time, the transmission rate and the subcarrier interval of each subcarrier signal are respectively the same as those of the transmitting end, and the down-sampled signal c'm(n) and transmitting end narrow-band filtering signal cm(n) equal, as shown in the following equation;
c′m(n)＝cm(n)
(11) by using MThe XL-order multi-tone matched filter bank is used for matching the M-channel parallel down-sampling signals c'm(n) performing filtering processing to obtain a receiving-end transform domain signal p'm(n) the expression is:
p′m(n)＝c′m(n)·Gm
wherein: gmThe coefficient of the M multiplied by L order multi-tone matched filter bank is represented, and the M multiplied by L order multi-tone matched filter bank is divided into M groups of receiving end transform domain signals p 'corresponding to the M paths of parallel receiving end transform domain signals'm(n), each matched filter contains L filter coefficients, wherein the ith filter coefficient of the mth matched filter is represented as gm+M×lM is more than or equal to 0 and less than or equal to M-1, L is more than or equal to 0 and less than or equal to L-1, namely L filter coefficients G of the mth matched filtermExpressed as: gm＝{gm；gm+M；gm+M×2；…；gm+M×(L-1)}；
(12) Converting the receiving end into the domain signal p'm(n) after being processed by the M-point FFT module, M paths of effective data z recovered by the receiving end are finally obtainedm(n), thereby achieving the purpose of realizing multi-carrier transmission without adopting multi-path intermediate frequency modulation and demodulation, and recovering M paths of effective data zmThe expression of (n) is:
zm(n)＝FFT[p′m(n)]
wherein the meanings of the symbols are as follows:
FFT [ ]: processing a function by an M-point FFT module;
Gm: m is more than or equal to 0 and less than or equal to M-1;
S2P [ ]: a serial-to-parallel converter processing function;
ωI: the center frequency of the intermediate frequency demodulator;
ωS: the operating frequency of the down converter;
t': the number of sampling points of the down-sampling module;
m: the number of subcarriers of the ship VDES system;
a receiving end receives a radio frequency signal s (k), substitutes the formula (a) into the formula (b) and meets the requirement of the following formula (c);
zm(n)＝am(n),0≤m≤M-1 (c)。
9. an FMT-based multi-carrier modem system for marine VDES system according to claim 8, wherein: the FMT multi-carrier modulation module comprises an IFFT module (2), a sending filter bank (3), an up-sampling module (4), a parallel-serial converter (5), an intermediate frequency modulator (6) and an up-converter (7); wherein:
IFFT module (2): m paths of parallel subcarrier signals are subjected to M-point IFFT processing to obtain M paths of parallel transform domain signals, and the M paths of parallel transform domain signals are sent to a sending filter bank (3);
transmit filter bank (3): receiving the M paths of parallel transform domain signals from an IFFT module (2), filtering the M paths of parallel transform domain signals to obtain M filtered signals, and sending the M filtered signals to an up-sampling module (4); wherein the transmit filter bank comprises M filters, each filter comprising L filter coefficients, wherein the ith filter coefficient of the mth filter is represented as fm+M×lM is more than or equal to 0 and less than or equal to M-1, L is more than or equal to 0 and less than or equal to L-1, namely L filter coefficients F of the mth filtermExpressed as: fm＝{fm；fm+M；fm+M×2；…；fm+M×(L-1)}；
Up-sampling module (4): receiving the M filtered signals from a sending filter bank (3), carrying out rate promotion on the M filtered signals to obtain M paths of parallel up-sampling signals, and sending the M paths of parallel up-sampling signals to a parallel-serial converter (5);
parallel-to-serial converter (5): receiving the M paths of parallel up-sampling signals from an up-sampling module (4), converting the M paths of parallel up-sampling signals into a path of serial baseband signals, and sending the signals to an intermediate frequency modulator (6);
intermediate frequency modulator (6): receiving the one path of serial baseband signal from the parallel-serial converter (5), carrying out quadrature modulation on the serial baseband signal to obtain an intermediate frequency signal, and sending the intermediate frequency signal to an up-converter (7);
up-converter (7): and receiving the intermediate frequency signal from an intermediate frequency modulator (6), carrying out up-conversion on the intermediate frequency signal to obtain a radio frequency signal, and sending the radio frequency signal to a receiving end.
10. An FMT-based multi-carrier modem system for marine VDES system according to claim 8, wherein: the FMT multi-carrier demodulation module comprises an FFT module (15), a matched filter bank (14), a down-sampling module (13), a serial-parallel converter (12), an intermediate frequency demodulator (11) and a down-converter (10); wherein:
down-converter (10): carrying out down-conversion processing on the radio-frequency signal received by the receiving end to obtain an intermediate-frequency signal, and sending the intermediate-frequency signal to an intermediate-frequency demodulator (11);
intermediate frequency demodulator (11): receiving the intermediate frequency signal from a down converter (10), carrying out quadrature demodulation on the intermediate frequency signal to obtain a path of serial baseband signal, and sending the serial baseband signal to a serial-to-parallel converter (12);
serial-to-parallel converter (12): receiving the serial baseband signal from an intermediate frequency demodulator (11), converting the serial baseband signal into M paths of baseband signals transmitted in parallel, and sending the baseband signals to a down-sampling module (13);
a downsampling module (13): receiving the M paths of parallel transmission baseband signals from a serial-parallel converter (12), carrying out rate reduction on the M paths of parallel transmission baseband signals to obtain M paths of parallel down-sampling signals, and sending the M paths of parallel down-sampling signals to a matched filter bank (14);
matched filter bank (14): receiving M paths of parallel down-sampling signals from a down-sampling module (13), filtering the M paths of parallel down-sampling signals to obtain M matched filtering signals, and sending the M matched filtering signals to an FFT module (15); wherein the matched filter bank comprises M matched filters, each matched filter comprising L filter coefficients, wherein the ith filter coefficient of the mth matched filter is represented as gm+M×lM is more than or equal to 0 and less than or equal to M-1, L is more than or equal to 0 and less than or equal to L-1, namely L filter coefficients G of the mth matched filtermExpressed as: gm＝{gm；gm+M；gm+M×2；…；gm+M×(L-1)}；
FFT module (15): and receiving the M matched filtering signals from a matched filter bank (14), and performing M-point FFT processing on the M matched filtering signals to obtain M paths of effective data recovered by a receiving end, namely M paths of subcarrier baseband data.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711039728.5A CN107911327B (en) | 2017-10-30 | 2017-10-30 | FMT-based multi-carrier modulation and demodulation method and system for ship VDES system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711039728.5A CN107911327B (en) | 2017-10-30 | 2017-10-30 | FMT-based multi-carrier modulation and demodulation method and system for ship VDES system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN107911327A CN107911327A (en) | 2018-04-13 |
| CN107911327B true CN107911327B (en) | 2020-12-18 |
Family
ID=61843031
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201711039728.5A Active CN107911327B (en) | 2017-10-30 | 2017-10-30 | FMT-based multi-carrier modulation and demodulation method and system for ship VDES system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN107911327B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109495494B (en) * | 2018-12-07 | 2022-01-28 | 遨海科技有限公司 | Frame structure configuration method, transmission device and system for VDES data transmission |
| CN111464229B (en) * | 2020-03-20 | 2020-11-06 | 上海航天电子通讯设备研究所 | Multi-channel multi-rate processing system suitable for VDE |
| CN117061295A (en) * | 2022-05-05 | 2023-11-14 | 中兴通讯股份有限公司 | Method, device, storage medium and electronic device for transmitting data sequence |
| CN115174332B (en) * | 2022-06-30 | 2023-11-10 | 成都天奥信息科技有限公司 | Ship/standard VDES system communication implementation method |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102263766A (en) * | 2011-08-29 | 2011-11-30 | 清华大学 | Frequency division multiple access method of variable-bandwidth FMT (frequency modulated transmitter) based on single-carrier transmission |
| CN104579177A (en) * | 2014-11-18 | 2015-04-29 | 中国电子科技集团公司第十研究所 | Digital down-conversion circuit suitable for filtering multi-tone modulation system |
| CN106656899A (en) * | 2016-12-29 | 2017-05-10 | 北京遥测技术研究所 | Method for realizing multicarrier VDE system modulation and demodulation of ship VDES system |
-
2017
- 2017-10-30 CN CN201711039728.5A patent/CN107911327B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102263766A (en) * | 2011-08-29 | 2011-11-30 | 清华大学 | Frequency division multiple access method of variable-bandwidth FMT (frequency modulated transmitter) based on single-carrier transmission |
| CN104579177A (en) * | 2014-11-18 | 2015-04-29 | 中国电子科技集团公司第十研究所 | Digital down-conversion circuit suitable for filtering multi-tone modulation system |
| CN106656899A (en) * | 2016-12-29 | 2017-05-10 | 北京遥测技术研究所 | Method for realizing multicarrier VDE system modulation and demodulation of ship VDES system |
Non-Patent Citations (2)
| Title |
|---|
| VHF水上移动频段内的VHF交换系统的技术特性;ITU国际电信联盟;《ITU-R M.2092-0建议书》;20151031;正文第5-9页 * |
| 海岸电台VHF数据通信系统设计探讨;郝连;《通信设计与应用》;20160731;第16页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN107911327A (en) | 2018-04-13 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107911327B (en) | FMT-based multi-carrier modulation and demodulation method and system for ship VDES system | |
| EP1702445B1 (en) | Modulation and demodulation of ofdm signals | |
| US20140192925A1 (en) | Method of and apparatus for reducing papr in filter-bank multi-carrier system | |
| CN101689872B (en) | Method for receiving and transmitting data in communication system of multi-band orthogonal frequency division multiplexing accession and communication apparatus using the same method | |
| EP2504940B1 (en) | Wireless data communications | |
| CN101119355A (en) | Transmission apparatus, reception apparatus and radio communication system | |
| WO1999063691A1 (en) | Ofdma signal transmitting apparatus and method | |
| JP2000049744A (en) | Transmission band division modulation/demodulation device and its method | |
| US20180278452A1 (en) | Method and device for controlling power in multi-carrier communication system | |
| CN107317784B (en) | Multi-band parallel filtering mixed carrier transmission method | |
| CN206272651U (en) | A kind of modulator for VDE systems | |
| CN108900461B (en) | Wireless communication system broadband signal design method based on large-scale MIMO | |
| CN108809880A (en) | A kind of the MIMO-FBMC system datas receiving/transmission method and device of low complex degree | |
| JP2000261403A (en) | Transmitter, its method and served medium | |
| US8630365B2 (en) | Transceiver for communicating over different media types | |
| CN106413006B (en) | A kind of ofdm communication method and system of uniform subband superposition | |
| EP0944197A1 (en) | Transmitter, receiver, transmitting method, and receiving method | |
| US7583742B2 (en) | Multi-band DMT receiver | |
| EP1395012A1 (en) | Modulation and demodulation of a combination of analog and digital signals | |
| US20190349157A1 (en) | Receiver, transmitter, communication system for subband communication and methods for subband communication | |
| US7061974B2 (en) | System and method for data transmission in DMT-based DSL modems | |
| JP2007521692A (en) | Digital radio frequency circuit | |
| CN108965184B (en) | Discrete multi-audio modulation multiplexing system and method | |
| CN112448903A (en) | Method and device for eliminating inter-subcarrier interference based on OFDM system | |
| CN114221672B (en) | Method for realizing frequency domain sparse signal receiving and transmitting system based on IFFT |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |