CN104883238A - Multi-carrier time division multiplexing modulation/demodulation method and system - Google Patents

Abstract

The invention provides a multi-carrier time division multiplexing modulation and demodulation method and system (MC-TDMA). Before multi-carrier modulation of input symbols, interleaved distribution and FFT transform are first performed, and time domain symbols are transformed into frequency domain symbol signals for MDFT processing. A transmitting end adopts an analysis filter bank structure, and signals are first subjected to pre-filtering and then IFFT transform. A pre-filter is located between the FFT at an NM point and the IFFT at an M point, the PAPR value of the system is reduced by using the symmetry of filter coefficients, and the frequency domain symbol signals are distributed to different sub-bands for multi-carrier modulation.

Description

A kind of multiplexing modulation/demodulation methods of carrier time division and system

Technical field

The present invention relates to multi-carrier modulation demodulation techniques, particularly the multiplexing modulation/demodulation methods of a kind of carrier time division and system (MC-TDMA).

Background technology

Mobile communication technology experienced by the development in four generations, and first generation radio communication belongs to analog communication, can only pass voice signal, and from second generation wireless network, mobile radio communication enters the digital network epoch, and voice-and-data can transmit simultaneously.(LTE) mobile communication from the second generation to forth generation, along with the development of modulation technique, data transfer rate has brought up to 1Gbps from 14.4Kbps.What second generation radio communication adopted is Gaussian Minimum Shift Keying (GMSK) modulation technique, and that 3G (Third Generation) Moblie adopts is Quadrature Phase Shift Keying (QPSK), and these two kinds of modulation techniques all belong to single-carrier modulated.

And in order to improve message transmission rate, be that the forth generation mobile radio communication of representative have employed multi-carrier modulation technology with LTE standard.In LTE standard, up employing single carrier frequency division multiple access technology (SC-FDMA), descending employing orthogonal frequency division multiplexing multiuser access technology (OFDMA).Multi-carrier modulation technology has anti-radio channel multi-path damping capacity, because in multi-carrier modulation, high speed signal is divided into multiple low speed signal by IFFT, then low speed signal is modulated in different sub carrier, synthesizes a signal with the long symbol cycle and transmits.

The major impetus of future mobile communications development is Internet of Things (IoT) and communicate (M2M) of Machine To Machine, and the feature that IoT with M2M communicates is randomness, asynchronous, short data, low delay and low-power consumption and low cost.Therefore be necessary study a kind of new modulation technique to meet future wireless system development demand, the present invention just in order to meet these require and propose.

Summary of the invention

The multiplexing modulator approach of a kind of carrier time division, is characterized in that carrying out interlace assignment to incoming symbol; Fast Fourier transform is utilized to carry out FFT conversion; Time-domain symbol is transformed to frequency domain symbol signal and carries out MDFT process.

According to another embodiment of the invention, the MDFT process in the multiplexing modulator approach of this carrier time division comprises sub-band analysis filtration process further, reverse Fourier transform process, and intertexture calculation process.According to another embodiment of the invention, the fast Fourier transform in the multiplexing modulator approach of this carrier time division is the conversion of NM-point quick Fourier further, here N, M be more than or equal to 1 positive integer.According to another embodiment of the invention, the sub-band analysis filtration process included by MDFT process in the multiplexing modulator approach of this carrier time division is further used for carrying out pre-filtering to NM point frequency domain symbol signal, again according to prototype filter construction of function coefficient matrix H, with coefficient matrix H, the right side carried out to NM point frequency domain symbol signal multiplied to 2NM point frequency domain symbol signal.

According to another embodiment of the invention, the coefficient matrix H used in the multiplexing modulator approach of this carrier time division is have the matrix circular of 4Nx2N the matrix element block M/2 that moves to right to obtain by one further.According to another embodiment of the invention, the coefficient matrix H used in the multiplexing modulator approach of this carrier time division, comprise following submatrix hi further, 0 and hi, 1: by RRC prototype function coefficient h (n) (0<=n<=NM-1) being divided into N number of sub-block (every sub-block comprises M point), diagonal matrix hi is formed respectively by the i-th sub-block front M/2 point and rear M/2 point, 0 and diagonal matrix hi, 1, i is the integer between 0 to N-1 here.According to another embodiment of the invention, the coefficient matrix H used in the multiplexing modulator approach of this carrier time division, wherein submatrix hi, 0 and submatrix hi, the arrangement mode of 1 is as follows:

$H=\left[\begin{array}{ccccccccc}{h}_{00}& 0& h_{10}& 0& h_{20}& ...& 0& h_{N-\mathrm{1,0}}& 0\\ 0& h_{01}& 0& h_{11}& 0& ...& h_{N-\mathrm{2,1}}& 0& h_{N-\mathrm{1,1}}\\ 0& h_{00}& 0& h_{10}& 0& ...& h_{N-\mathrm{2,1}}& 0& h_{N-\mathrm{1,1}}\\ h_{N-\mathrm{1,1}}& 0& h_{01}& 0& h_{11}& ...& 0& h_{N-\mathrm{2,1}}& 0\\ .& .& .& .& .& .& .& .& .\\ .& .& .& .& .& .& .& .& .\\ .& .& .& .& .& .& .& .& .\\ h_{\mathrm{1,0}}& 0& h_{\mathrm{2,0}}& 0& h_{\mathrm{3,0}}& ...& 0& h_{00}& 0\\ 0& h_{\mathrm{1,1}}& 0& h_{\mathrm{2,1}}& 0& ...& h_{N-\mathrm{1,1}}& 0& h_{01}\end{array}\right]$

According to another embodiment of the invention, the reverse Fourier transform that the MDFT process in the multiplexing modulator approach of this carrier time division comprises is a reverse Fourier transform of 2N M-point further.

The present invention also proposes a kind of carrier time division multiplexing demodulation method, the method comprises: go prefix to received signal, the signal after prefix is removed through equalizer equilibrium, carry out IMDFT process synthesis and be entirely with frequency-region signal, the frequency-region signal of synthesis carries out fast reverse Fourier transform (IFFT) conversion and obtains time-domain signal, again the signal exported is carried out that symbol is counter to sort, penetrate process through symbol reflection and obtain the transmitting terminal incoming symbol signal rebuild.

According to another embodiment of the invention, the IMDFT process in this carrier time division multiplexing demodulation method comprises reciprocal cross further and knits calculation process, Fourier transform process, and the process of subband integrated filter.

According to another embodiment of the invention, the fast reverse Fourier transform in this carrier time division multiplexing demodulation method is a NM-point fast reverse Fourier transform further.

According to another embodiment of the invention, the Fourier transform that the IMDFT process in this carrier time division multiplexing demodulation method comprises is a 2N M-point Fourier transform further.

According to another embodiment of the invention, the subband integrated filter process included by IMDFT process in this carrier time division multiplexing demodulation method, be further used for carrying out post-filtering to 2NM point frequency domain symbol signal, then it is multiplied to NM point frequency domain symbol signal to carry out the right side according to the transpose pair 2NM point frequency domain symbol signal of coefficient matrix H.

The present invention also proposes the multiplexing MDFT system of a kind of carrier time division, and this system comprises transmitting terminal and receiving terminal, and transmitting terminal comprises: for carrying out the sign map unit that sign map obtains complex symbol signal to binary bit sequence; For carrying out the symbol sequencing unit of interlace assignment to incoming symbol, for time-domain symbol signal being transformed to the fast Fourier transform unit of frequency domain symbol signal; Make the MDFT unit of reverse Fourier transform conversion after carrying out pre-filtering as prefilter to frequency domain symbol signal, MDFT unit adopts analysis filterbank structure; Described receiving terminal comprises: that removes prefix, equilibrium treatment acquisition mark signal to received signal removes prefix unit, equalizer; Knitting computing for carrying out reciprocal cross, computing being knitted to reciprocal cross and obtains the IMDFT unit acquisition mark signal that signal carries out MDFT inverse transformation, obtaining the reverse fast Fourier transform unit of transmitting terminal reconstruction signal for the mark signal of acquisition being carried out IFFT conversion.

According to one embodiment of present invention, MDFT unit comprises, sub-band analysis filtration part: for carrying out pre-filtering to NM point frequency domain symbol signal, again according to prototype filter construction of function coefficient matrix H, with coefficient matrix H, the right side carried out to NM point frequency domain symbol signal multiplied to 2NM point frequency domain symbol signal; IFFT conversion fraction: obtain 2NM point time-domain signal for carrying out 2N M-point IFFT conversion to 2NM point frequency domain symbol signal; Intertexture arithmetic section: obtain NM point output complex symbol signal for carrying out intertexture computing to 2NM point time-domain signal.

According to another embodiment of the invention, the reverse Fourier transform in described MDFT unit, its reverse Fourier transform implemented is a reverse Fourier transform of 2N M-point.

According to another embodiment of the invention, described reverse fast Fourier transform unit, its reverse fast Fourier transform implemented is the reverse fast Fourier transform of a NM-point, here N, M be more than or equal to 1 positive integer.

According to another embodiment of the invention, described IMDFT unit, it is reduced to 2NM point frequency domain symbol signal for mark signal NM point being removed channel disturbance, post-filtering is carried out to 2NM point frequency domain symbol signal, then it is multiplied to NM point frequency domain symbol signal to carry out the right side according to the transpose pair 2NM point frequency domain symbol signal of coefficient matrix H.

The MC-TDMA system configuration that the present invention proposes realizes simple, transmitting terminal is realized by incoming symbol interlace assignment and MDFT bank of filters, receiving terminal adopts MDFT synthesis filter banks structure, adopt FFT converter unit, intertexture computing is eliminated between adjacent sub-bands and is disturbed, thus allowing the ability of the existing anti-unlimited channel multi-path decay of system also have the ability of anti-carrier frequency drift, MC-TDMA collects the advantage of every other modulating system in a system, and transmitting terminal adopts analysis filterbank structure.Receiving terminal adopts synthesis filter banks structure, and receiving terminal can disposable recovery NM point transmitting terminal input signal, and time delay is little, and can save the resource that prefix takies, and adopts frequency domain zero setting equalizer, realizes simply.

Accompanying drawing explanation

Fig. 1 MC-TDMA multicarrier modulation system theory structure block diagram;

The multinomial decomposition of frequency domain MDFT bank of filters in Fig. 2 MC-TDMA realizes block diagram;

Fig. 3 PAPR analog result schematic diagram;

Fig. 4 MC-TDMA system symbol error rate analog result;

The anti-carrier frequency drift analog result of Fig. 5 MC-TDMA system.

Embodiment

As shown in the specification and claims, unless context clearly points out exceptional situation, the word such as " ", " ", " one " and/or " being somebody's turn to do " not refers in particular to odd number, also can comprise plural number.In general, term " comprises " only points out with " comprising " step and element that comprise and clearly identifying, and these steps and element do not form one and exclusively to enumerate, and method or equipment also may comprise other step or element.

In the forth generation mobile radio communication taking LTE standard as representative, employ multi-carrier modulation technology widely, particularly down link have employed orthogonal frequency division multiplexing multiuser access (OFDMA) technology.Multi-carrier modulation technology has natural anti-radio channel multi-path damping capacity, because in multi-carrier modulation, high speed signal is divided into multiple low speed signal by IFFT, then low speed signal is modulated in different sub carrier, synthesizes a signal with the long symbol cycle and transmits.Due to the expansion of symbol period, the ability of signal opposing multipath fading obtains large increase, and therefore, multi-carrier modulation technology is the indispensable part of high-speed radiocommunication.

OFDMA and SC-FDMA is comparatively responsive to carrier frequency drift.In addition, the PAPR value of OFDMA is bigger than normal.The PAPR value of SC-FDMA is little by contrast.Namely the LTE standard adopted in present forth generation mobile radio communication adopts SC-FDMA in uplink communication.Owing to will keep the multi-carrier nature of SC-FDMA modulation signal, that LTE standard adopts is the SC-FDMA (SC-LFDMA) of concentrated intercalation model.Although the PAPR value of SC-LFDMA is lower than OFDMA, but still and the theoretical minimum value of PAPR have very large difference, that is possibility that is also improved of its PAPR.OFDMA and SC-FDMA is to send and the sub-carrier frequencies of receiving terminal need keep strict synchronous, and this is to receive and the crystal oscillator precision of transmitting terminal proposes very high requirement.

The reason that existing multicarrier modulation system PAPR value is large is the use due to reverse Fourier transform (IFFT conversion).Because the basic function of IFFT conversion is complex-exponential function, and complex-exponential function becomes large by the superposition amplitude value that is multiplied of random mark, and special in the complex exponential phase place after being multiplied is consistent, range value is maximum, and PAPR value is at this moment also maximum.Reduce the method for PAPR value in OFDMA system a lot, but these methods can only solve the high problem of PAPR value, OFDMA system subcarrier can not be solved completely and to drift about the impact that systematic function is brought.

The optional method improving the anti-carrier frequency drift ability of multicarrier modulation system is the IFFT replaced by bank of filters in OFDMA system, because bank of filters prototype function frequency characteristic is better than the frequency characteristic of the rectangular window function in IFFT, the interference (ICI) between subcarrier can be eliminated preferably.In addition, good prototype function frequency characteristic can also improve the power spectral density of system, reduces the power leakage between subband, improves the validity of Signal transmissions.But the feature of filter bank multi-carrier modulation (FBMC) system, one is that PAPR value is comparatively large, and two is that time delay is long, because good frequency characteristic requires very long prototype filter function coefficients.These features constrain the application in practice of FBMC multicarrier modulation system.

Analysis shows, reducing PAPR value has two kinds of basic skills, and one is the power peak reducing modulation symbol, and two is the length shortening IFFT conversion.The length shortening IFFT conversion can also reduce the frequency resolution of modulating system simultaneously, improves the anti-carrier frequency drift ability of system.Due to the PAPR that theory minimum PAPR value is former incoming symbol signal, so if modulation output symbol can approach former incoming symbol as much as possible, so PAPR value is lower.In single-carrier modulated, first incoming symbol carries out the mapping of FFT carrier wave, and then carries out IFFT modulation.According to the pattern that carrier wave maps, the modulation symbol after FFT/IFFT conversion is the weighted sum (concentrate and map) of incoming symbol, or the repetition of incoming symbol (interlace map).PAPR value directly affects the service time of battery of mobile terminal (mobile phone), therefore, more low better for PAPR value uplink communication.

Modulator approaches all at present and system (comprising the system used in a standard) all can not solve the problem of high PAPR and high carrier frequency drift susceptibility in OFDMA simultaneously.Present invention incorporates the advantage of SC-FDMA and FBMC modulation technique, in a modulating system, successfully solve above-mentioned two puzzlement radio communication physical layers problem for many years.The MC-TDMA multicarrier modulation system that the present invention proposes not only may be used for high-speed communication and also can be used for IoT with M2M and communicate.

A specific embodiment of the present invention is the multiplexing modulation-demo-demodulation method of a kind of carrier time division, before multi-carrier modulation is carried out to incoming symbol, first interlace assignment and FFT conversion are carried out to incoming symbol, time-domain symbol is transformed to frequency domain symbol signal, then MDFT process is carried out to frequency domain symbol signal.The description that it should be noted that herein is only the main process of a specific embodiment, and should not be considered to be unique embodiment, wherein each step is not necessary, and whole flow process and concrete steps thereof are also not limited to figure neutralization description above.Such as, still can do before interlace assignment is carried out for incoming symbol more corresponding give treatment step, and the order of FFT conversion and MDFT process can do suitable adjustment.Obviously; for those skilled in the art; after understanding content of the present invention and principle; all may when not deviating from the principle of the invention, structure; various correction in form and details and change are carried out to this system, but these are revised and change still within claims of the present invention.

In MDFT processing section, what distinguish to some extent with classical MDFT process structure with traditional FBMC (OFDM/OQAM) modulation scheme is, what in traditional FMBC, transmitting terminal adopted is synthesis filter banks structure, and in the present invention, transmitting terminal adopts analysis filterbank structure, and what carry out after signal carries out pre-filtering is IFFT conversion instead of traditional FFT conversion.The position of prefilter is between NM point FFT and M point IFFT, and it serves a dual purpose in MC-TDMA, and one is the PAPR value utilizing the symmetry of filter coefficient to reduce system, and two is frequency domain symbol signal is assigned to different sub-band carry out multi-carrier modulation.Description is herein only the main process of a specific embodiment, should not be considered to be unique embodiment, and wherein each step is not necessary, and whole flow process and concrete steps thereof are also not limited to figure neutralization description above.

A further specific embodiment of the present invention then proposes a kind of carrier time division multiplex system, this system comprises transmitting terminal and receiving terminal, and transmitting terminal comprises: for carrying out the sign map unit that sign map obtains complex symbol signal to binary bit sequence; For carrying out the symbol sequencing unit of interlace assignment to incoming symbol, for time-domain symbol signal being transformed to fast fourier transform (FFT conversion) unit of frequency domain symbol signal; Make the MDFT unit of IFFT conversion after carrying out pre-filtering as prefilter to frequency domain symbol signal, MDFT unit adopts analysis filterbank structure; Receiving terminal comprises: that removes prefix, equilibrium treatment acquisition mark signal to received signal removes prefix unit, equalizer; Knitting computing for carrying out reciprocal cross, computing being knitted to reciprocal cross and obtains the IMDFT unit that signal carries out MDFT inverse transformation, obtaining the IFFT unit of transmitting terminal reconstruction signal for the mark signal of acquisition being carried out inverse fast fourier transform (IFFT conversion).Description is herein only the main process of a specific embodiment, should not be considered to be unique embodiment, and wherein each unit is not necessary, and whole flow process and concrete steps thereof are also not limited to figure neutralization description above.Such as, depend on the communication quality quality of wireless channel, here equalizer can adopt frequency domain zero setting equalizer also can adopt non-zero setting type equalizer, blind equalizer can be adopted also can to adopt non-blind equalizer, self-adaptation type equalizer can be adopted also can to adopt non-self-adapting type equalizer.Obviously; similar; for those skilled in the art; after understanding content of the present invention and principle; all may when not deviating from the principle of the invention, structure; various correction in form and details and change are carried out to this system, but these are revised and change still within claims of the present invention.

Further, the position of transmitting terminal prefilter is between NM point FFT and M point IFFT, and described filter coefficient has symmetry, and frequency domain symbol signal is assigned to different sub-band and carries out multi-carrier modulation.

Be N for access customer number, the sub-carrier number of each user is the system of M, total sub-carrier number is L=NM, sign map unit carries out sign map, obtain M time domain incoming symbol signal, symbol sequencing unit adopts interlace assignment mode assignments on NM time point to M time domain incoming symbol signal, and FFT converter unit carries out FFT computing to NM point time-domain symbol signal and obtains NM point frequency domain symbol signal.

Further, MDFT unit comprises, sub-band analysis filtration part: obtain NM point frequency domain symbol signal for carrying out FFT conversion to NM point transmitting terminal incoming symbol signal, according to prototype filter construction of function coefficient matrix H, with coefficient matrix H, the right side carried out to NM point frequency domain symbol signal multiplied to 2NM point frequency domain symbol signal; IFFT conversion fraction: obtain 2NM point time-domain signal for carrying out 2N M-point IFFT conversion to 2NM point frequency domain symbol signal; Intertexture arithmetic section: obtain NM point output complex symbol signal for carrying out intertexture computing to 2NM point time-domain signal.2NM point time domain complex signal is divided into upper and lower two-way by intertexture arithmetic section, a upper road signal does not have time delay, next road signal has a time delay, after 2 times of sampling are carried out to upper and lower two paths of signals, alternately get real part and imaginary part respectively, synthesis complex symbol signal, makes 2NM point complex signal become NM point complex signal.Coefficient matrix H is obtained by M/2 dot cycle displacement by the coefficient of MDFT analysis filterbank, and MDFT analysis filterbank coefficient is made up of square root raised cosine RRC function, and the dimension of H matrix is 2NMxNM.Described structure coefficient matrix H specifically comprises, the matrix circular of MxNM the matrix element block M/2 that moves to right is had to obtain the matrix H that size is 2NMxNM by one, the M/2 point on the M/2 point shift-in left side that the right is shifted out, is shifted from first MxNM matrix-block until 2N-1 matrix-block terminates.

Further, receiving terminal equalizer carries out FFT conversion and obtains frequency-region signal after going prefix to mark signal, by the system function of frequency-region signal divided by channel, obtains through IFFT conversion the signal removing channel disturbance.Receiving terminal IMDFT unit: the mark signal for NM point being removed channel disturbance is reduced to 2NM point symbol signal, 2N M-point FFT conversion is carried out to 2NM point symbol signal and obtains 2NM point frequency-region signal, then the transposed matrix H of the right multiplying factor matrix H of 2NM point frequency-region signal is obtained NM point signal

The MC-TDMA system configuration that the present invention proposes realizes simple, and transmitting terminal is realized by incoming symbol interlace assignment and MDFT bank of filters, and receiving terminal adopts IMDFT synthesis filter banks structure, adopts FFT converter unit.Intertexture computing is eliminated between adjacent sub-bands and is disturbed, and after intertexture computing, 2NM point symbol signal becomes NM point symbol signal.Sub-carrier number is M, N number of multi-carrier modulation symbol transmits in N number of time period respectively, system can be allowed to obtain optimum time frequency resolution by adjustment N and M, thus allow the ability of the existing anti-radio channel multi-path decay of system also have the ability of anti-carrier frequency drift, MC-TDMA collects the advantage of every other modulating system in a system, and transmitting terminal adopts analysis filterbank structure.Receiving terminal adopts synthesis filter banks structure, and receiving terminal can disposable recovery NM point transmitting terminal input signal, and time delay is little, and can save the resource that prefix takies, and adopts frequency domain zero setting equalizer, realizes simply.

Below in conjunction with accompanying drawing and instantiation, enforcement of the present invention is described in further detail.Apparently, the accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, can also apply the present invention to other similar sight according to these accompanying drawings.Unless obviously or separately explained from language environment, in figure, identical label represents same structure and operation.

Be illustrated in figure 1 MC-TDMA multicarrier modulation system theory structure block diagram, MC-TDMA multicarrier modulation system comprises: transmitting terminal and receiving terminal, transmitting terminal comprises, sign map unit, symbol sequencing unit, NM-point FFT converter unit, sub-band analysis filtration, 2N M-point IFFT conversion, intertexture arithmetic element; Receiving terminal comprises, and arithmetic element is knitted in reciprocal cross, 2N M-point FFT converter unit, sub-band synthesis filter, NM-point IFFT converter unit, the anti-sequencing unit of symbol, the anti-map unit of symbol.

Input binary bit sequence s (n) carries out sign map through sign map unit, and sign map by QPSK or QAM method, can obtain the complex symbol signal needing to carry out modulating after sign map.Complex symbol signal processes symbol sequence through symbol sequencing unit, symbol sequence adopts intertexture sequencing model, that is, every N point insertion mark signal, for single user (uplink), the value between two non-zero symbol signals is zero, for multi-user (downlink transfer), value between two non-zero symbol signals is the signal of other users, obtains NM point symbol signal after sequencing unit process.The sequence mark signal obtained processes through NM-point FFT converter unit, then after sub-band analysis filtration unit carries out analysis filtered to signal, send into 2N M-point IFFT converter unit to convert, obtain the signal after modulation, the signal obtained carries out intertexture computing, sends into channel and be sent to receiving terminal after prefixing.Receiving terminal goes prefix to received signal, through equalizer, equilibrium treatment is carried out to the signal after removal prefix, send into after reciprocal cross knits arithmetic element process again, M-point FFT converter unit carries out 2N M-point FFT to it and converts acquisition frequency domain sub-band signal, synthesize after subband integrated filter and be entirely with frequency-region signal, the frequency-region signal of synthesis is sent into NM-point IFFT converter unit and is obtained time-domain signal, the signal that IFFT converter unit exports is carried out that symbol is counter to sort, penetrates cell processing finally by symbol reflection and obtain the transmitting terminal incoming symbol signal rebuild.

Specifically, to multiple access modulating system, suppose that total sub-carrier number is L=NM, the sub-carrier number that each user assigns to is M.Sub-carrier signal obtains M mark signal after sign map unit maps, and M mark signal adopts interleaved symbol allocation model to be assigned on L time point through intertexture arithmetic element.Carry out L point FFT to complex symbol signal to convert, time-domain symbol signal is transformed to frequency domain and obtains frequency-region signal.

As shown in Figure 2, MDFT bank of filters is the part before FFT unit, is made up of three parts, and Part I is pre-filter, and Part II is IFFT converter unit, and Part III is signal interleaving arithmetic element.

MDFT bank of filters comprises: sub-band analysis filtration part, IFFT conversion fraction, signal interleaving arithmetic section, after sub-band analysis filtration part and IFFT conversion fraction complete pre-filtering and IFFT conversion, signal interleaving arithmetic section carries out intertexture computing to 2NM point symbol signal, obtains the output of NM point complex symbol and transmits.

The analysis filterbank that pre-filter is M/2 (port number getting bank of filters is M) by an extraction yield forms, and carries out Substrip analysis process, obtain M subband signal to input signal x (n).Choose the bank of filters that prototype function coefficient is h (n), z in Fig. 2 ^-1represent a time delay.Each frame NM point incoming symbol signal x (n) enters prefilter along delay line, then carries out M/2 sampling, obtains NM road and exports, and NM road exports and obtain the output of M road after superposition.Wherein, N is determined by the number of users of modulating system, and M is determined by sub-carrier number.M road exports and obtain M road modulation signal after inverse fourier transform (IFFT).Modulation signal needs to carry out intertexture computing before transmitting, thus removes the interference of intersubband.Intertexture computing comprises the computing of transmitting terminal intertexture and computing two parts are knitted in receiving terminal reciprocal cross, withdrawal device, real and imaginary-part operation unit that the intertexture arithmetic section of transmitting terminal is 2 by decimation value form, signal is divided into upper and lower two-way after entering intertexture arithmetic section, a road does not have time delay above, below a road have a time delay.Upper and lower two paths of signals, after carrying out 2 times of sampling, alternately gets real part and imaginary part, and the real part of extraction and imaginary values are synthesized a new complex symbol signal value and transmitted.The real part of adjacent two passages and imaginary-part operation need intertexture to carry out, if on last passage, a road carries out is real part computing, so imaginary-part operation need be carried out in current channel Shang mono-tunnel.In Fig. 2, z ^-1represent a time delay, ↓ M/2 represents that M/2 samples, and ↑ M/2 represents M/2 interpolation, and h (n) represents RRC prototype filter function, Re{} and IM{} is real imaginary-part operation, x (n) and represent transmitting terminal input signal and receiving terminal reconstruction signal respectively.

Due to 2 times of sampling and intertexture computing, the input of 2NM point becomes NM point and exports, thus ensures that the incoming symbol number of MC-TDMA system is consistent with output.After above-mentioned process, Cyclic Prefix is added to the complex symbol signal of synthesis, then enter wireless channel and send.

MDFT bank of filters optimum can be in the following way, pre-filtering part is according to prototype filter construction of function coefficient matrix H, with coefficient matrix H, the right side carried out to NM point frequency domain symbol signal multiplied to 2NM point frequency domain symbol signal, IFFT conversion fraction carries out 2N M-point IFFT to 2NM point frequency domain symbol signal and converts, obtain 2NM point time-domain signal, intertexture arithmetic section carries out intertexture computing to 2NM point time-domain signal, obtains NM point complex symbol signal and exports.

Specifically, as follows according to the method for prototype filter construction of function coefficient matrix H, if prototype filter is RRC (square root raised cosine function) function, then prototype filter function coefficients h (n) can be expressed as:

$h\left(n\right)=\frac{\frac{4\mathrm{rn}}{M}\cos \left[\frac{\mathrm{\&pi;}(1+r)n}{M}\right]+\sin \left[\frac{\mathrm{\&pi;}(1-r)n}{M}\right]}{[1-{\left(\frac{4\mathrm{rn}}{M}\right)}^2]\mathrm{\&pi;n}},-\&infin;\&le;n<\&infin;$

$h\left(0\right)=\frac{1}{M}+\frac{r}{M}(\frac{4}{\mathrm{\&pi;}}-1)$

$h(\&PlusMinus;\frac{M}{4r})=-\frac{r}{M}\left\{\frac{2}{\mathrm{\&pi;}}\cos \right[\frac{\mathrm{\&pi;}}{4r}(1+r)]-\cos [\frac{\mathrm{\&pi;}}{4r}(1-r)\left]\right\}$

Wherein, M equals sub-carrier number, and r represents the roll-off factor of RRC function, and determine the stopband attenuation factor of RRC function filter, the scope of RRC function variable n is determined by the length NM of prefilter.Said method and design parameter setting are not limited to the structure of coefficient matrix H.

Structure coefficient matrix H, supposes that access customer number is N, and to be M, H matrix be the sub-carrier number that each user assigns to has the matrix circular of 4Nx2N the matrix element block M/2 that moves to right to obtain by one, wherein, and matrix element block h _{i, 0}, h _{i, 1}(0<=i<=N-1) be two diagonal matrixs, if RRC prototype function coefficient h (n) (0<=n<=NM-1) is divided into N number of sub-block (every sub-block comprises M point), h _{i, 0}, h _{i, 1}be made up of the i-th sub-block front M/2 point and rear M/2 point respectively.The size of H is 2NMxNM.In the process of cyclic shift, the M/2 point on the M/2 point shift-in left side that the right is shifted out.Displacement terminates to 2N-1 matrix-block from first MxNM matrix-block.

$H=\left[\begin{array}{ccccccccc}{h}_{00}& 0& h_{10}& 0& h_{20}& ...& 0& h_{N-\mathrm{1,0}}& 0\\ 0& h_{01}& 0& h_{11}& 0& ...& h_{N-\mathrm{2,1}}& 0& h_{N-\mathrm{1,1}}\\ 0& h_{00}& 0& h_{10}& 0& ...& h_{N-\mathrm{2,1}}& 0& h_{N-\mathrm{1,1}}\\ h_{N-\mathrm{1,1}}& 0& h_{01}& 0& h_{11}& ...& 0& h_{N-\mathrm{2,1}}& 0\\ .& .& .& .& .& .& .& .& .\\ .& .& .& .& .& .& .& .& .\\ .& .& .& .& .& .& .& .& .\\ h_{\mathrm{1,0}}& 0& h_{\mathrm{2,0}}& 0& h_{\mathrm{3,0}}& ...& 0& h_{00}& 0\\ 0& h_{\mathrm{1,1}}& 0& h_{\mathrm{2,1}}& 0& ...& h_{N-\mathrm{1,1}}& 0& h_{01}\end{array}\right]$

We illustrate matrix H to an object lesson below, and h _{i, 0}and h _{i, 1}structure.If number of users N=2, sub-carrier number M=8, roll-off factor r=0.5, obtain prototype function coefficient h (n) according to RRC formula:

$h\left(n\right)=\frac{\frac{4*0.5*n}{8}\cos \left[\frac{\mathrm{\&pi;}(1+0.5)n}{8}\right]+\sin \left[\frac{\mathrm{\&pi;}(1-0.5)n}{8}\right]}{[1-{\left(\frac{4*0.5*n}{8}\right)}^2]\mathrm{\&pi;n}},-4\&le;n<4,n\&NotEqual;0,-4$

$h\left(0\right)=\frac{1}{8}+\frac{0.5}{8}(\frac{4}{\mathrm{\&pi;}}-1)$

$h(-4)=-\frac{0.5}{8}\left\{\frac{2}{\mathrm{\&pi;}}\cos \right[\frac{\mathrm{\&pi;}}{4*0.5}(1+0.5)]-\cos [\frac{\mathrm{\&pi;}}{4*0.5}(1-0.5)\left]\right\}$

Matrix element block h _0,0, h _0,1, h _1,0, h _1,1be respectively:

$h_{\mathrm{0,0}}=\left[\begin{array}{cccc}h\left(0\right)& & & \\ & h\left(1\right)& & \\ & & h\left(2\right)& \\ & & & h\left(3\right)\end{array}\right]$

$h_{\mathrm{0,1}}=\left[\begin{array}{cccc}h\left(4\right)& & & \\ & h\left(5\right)& & \\ & & h\left(6\right)& \\ & & & h\left(7\right)\end{array}\right]$

$h_{\mathrm{1,0}}=\left[\begin{array}{cccc}h\left(8\right)& & & \\ & h\left(9\right)& & \\ & & h\left(10\right)& \\ & & & h\left(11\right)\end{array}\right]$

$h_{\mathrm{1,1}}=\left[\begin{array}{cccc}h\left(12\right)& & & \\ & h\left(13\right)& & \\ & & h\left(14\right)& \\ & & & h\left(15\right)\end{array}\right]$

Finally obtain matrix H to equal

$H=\left[\begin{array}{cccc}{h}_{\mathrm{0,0}}& 0& h_{\mathrm{1,0}}& 0\\ 0& h_{\mathrm{0,1}}& 0& h_{\mathrm{1,1}}\\ 0& h_{\mathrm{0,0}}& 0& h_{\mathrm{1,0}}\\ h_{\mathrm{1,1}}& 0& h_{\mathrm{0,1}}& 0\end{array}\right]$

With coefficient matrix H, the right side carried out to NM point frequency domain signal X (k) multiplied to 2NM point symbol signal, then, the computing of 2N M-point IFFT (inverse fast fourier transform) is carried out to 2NM point symbol signal, obtain 2NM point time-domain signal.

Receiving terminal carries out the operation contrary with transmitting terminal.First receiving terminal carries out prefix process to the received signal, then carry out balancing operational through equalizer and remove channel disturbance, after arithmetic element process is knitted in feeding reciprocal cross, M-point FFT converter unit carries out 2N M-point FFT to it and converts acquisition frequency domain sub-band signal, full band signal is synthesized through subband integrated filter, send into NM-point IFFT converter unit and obtain time-domain signal, the signal exported converter unit carries out that symbol is counter to sort, and penetrates cell processing obtain transmitting terminal reconstruction mark signal through symbol reflection.

The present invention can adopt frequency domain zero setting equalizer.Frequency domain zero setting equalizer transforms to frequency domain by going the signal after prefix to carry out FFT, then divided by system function H (k) (Fourier transform of channel impulse response h (n)) of channel, the signal that IFFT (inverse fast fourier transform) conversion obtains removing channel disturbance is finally carried out.

MC-TDMA is a kind of multicarrier modulation system based on bank of filters, uses DFT (MDFT) bank of filters revised.MC-TDMA is on the basis of traditional filter bank multi-carrier modulating system (FBMC), obtains by introducing the advantage of single carrier modulation system.MC-TDMA system has the two-fold advantage of multicarrier and single-carrier system, and existing low-down power closed (PAPR) has again very strong anti-radio channel multi-path decay and the asynchronous energy of carrier wave.PAPR value is close to theoretical minimum, and the PAPR value of more multiplexing than the single carrier frequency division adopted in LTE standard (SC-FDMA) system is also low.Emulation shows, the anti-carrier wave ability to be asynchronous of MC-TDMA system is more than 10 times of OFDM.MC-TDMA multicarrier modulation system both can be used for uplink communication (uplink) and also can be used for downlink communication (downlink).The power consumption that MC-TDMA system can reduce terminal equipment also can reduce the power consumption of base station equipment, can reduce the required precision to terminal equipment clock frequency simultaneously.MC-TDMA system has flexible design, realizes the feature that is easy to, can be used for high-speed communication and also can be used for Internet of Things communication.

Fig. 3,4,5 give the analog result figure to the MC-TDMA multicarrier modulation system Performance comparision that the present invention proposes.Fig. 3 provides the analog result of PAPR, and in figure, s represents that symbol is shifted, and solid line represents OFDMA system, and represented by dotted arrows SC-FDMA system, dotted line represents MC-TDMA system.Can clearly find out from Fig. 3, the PAPR value of MC-TDMA system is minimum, has fairly obvious improvement than OFDMA and SC-FDMA.The comparison diagram of the is-symbol error rate that Fig. 4 provides, also can find out from figure, the error rate of MC-TDMA is minimum.Fig. 5 gives the Performance comparision of the anti-subcarrier drift of system, and as can be seen from the figure, when the carrier frequency drift of 10%, MC-TDMA still has good performance, and at this moment OFDMA and SC-FDMA system can not work.Clearly can find out that the present invention proposes MC-TDMA system from analog result all better than the performance of OFDMA and SC-FDMA.MC-TDMA both may be used for uplink communication and also may be used for downlink communication, both may be used for high-speed communication and also may be used for asynchronous low-speed communication.

Execution mode cited by the present invention is described above, but the case just adopted for the ease of understanding the present invention, and be not used to limit the present invention.When not deviating from inventive concept and essence; those of ordinary skill in the art can make various corresponding modifications and variations according to the present invention what implement in form or in details; scope of patent protection of the present invention, is still as the criterion with the scope that claims define.

Claims (14)

1. the multiplexing modulator approach of carrier time division, is characterized in that, is assigned to by time domain incoming symbol signal a series of time point carries out interlace assignment to obtain a series of time domain incoming symbol signal; Utilize fast Fourier transform to carry out FFT conversion to a series of time domain incoming symbol signal and obtain a series of frequency domain symbol signal; MDFT process is carried out to frequency domain symbol signal.

2. modulator approach according to claim 1, is characterized in that: described fast Fourier transform comprises: its Fourier transform implemented is the conversion of NM-point quick Fourier, here N, M be more than or equal to 1 positive integer.

3. modulator approach according to claim 1, it is characterized in that: described MDFT process comprises: pre-filtering is carried out to NM point frequency domain symbol signal, again according to prototype filter construction of function coefficient matrix H, with coefficient matrix H, the right side carried out to NM point frequency domain symbol signal multiplied to 2NM point frequency domain symbol signal, carry out 2N M-point IFFT to 2NM point frequency domain symbol signal to convert, obtain 2NM point time domain complex signal; Intertexture computing is carried out to 2NM point time domain complex signal, obtains NM point and export complex symbol signal.

4. modulator approach according to claim 3, it is characterized in that: described coefficient matrix H is obtained by M/2 dot cycle displacement by the coefficient of MDFT analysis filterbank, MDFT analysis filterbank coefficient is made up of square root raised cosine RRC function, and the dimension of coefficient matrix H is 2NM x NM.

5. modulator approach according to claim 4, is characterized in that: described coefficient matrix H, comprises following submatrix h _{i, 0}and h _{i, 1}: by RRC prototype function coefficient h (n) (0<=n<=NM-1) is divided into N number of sub-block, every sub-block comprises M point, forms diagonal matrix h respectively by the i-th sub-block front M/2 point and rear M/2 point _{i, 0}with diagonal matrix h _{i, 1}, i is the integer between 0 to N-1 here.

6. modulator approach according to claim 5, is characterized in that: the submatrix h that described coefficient matrix H comprises _{i, 0}with submatrix h _{i, 1}arrangement mode as follows:

。

7. a carrier time division multiplexing demodulation method, it is characterized in that: go prefix to received signal, the signal after prefix is removed through equalizer equilibrium, carry out IMDFT process synthesis and be entirely with frequency-region signal, the frequency-region signal of synthesis carries out fast reverse Fourier IFFT conversion and obtains time-domain signal, again the time-domain signal exported is carried out that symbol is counter to sort, penetrate process through symbol reflection and obtain the transmitting terminal incoming symbol signal rebuild.

8. demodulation method according to claim 7, it is characterized in that: described IMDFT process comprises: calculation process is knitted in reciprocal cross, Fourier transform process, and the process of subband integrated filter, described Fourier transform, its Fourier transform implemented is a 2N M-point Fourier transform, and the process of described subband integrated filter is specially, post-filtering is carried out to 2NM point frequency domain symbol signal, then it is multiplied to NM point frequency domain symbol signal to carry out the right side according to the transpose pair 2NM point frequency domain symbol signal of coefficient matrix H.

9. demodulation method according to claim 7, is characterized in that: described fast reverse Fourier transform, and its reverse Fourier transform implemented is a NM-point fast reverse Fourier transform.

10. the multiplexing MDFT system of carrier time division, this system comprises transmitting terminal and receiving terminal, it is characterized in that, transmitting terminal comprises: for carrying out the sign map unit that sign map obtains complex symbol signal to binary bit sequence; For carrying out the symbol sequencing unit of interlace assignment to incoming symbol, for time-domain symbol signal being transformed to the fast Fourier transform unit of frequency domain symbol signal; Make the MDFT unit of reverse Fourier transform conversion after carrying out pre-filtering as prefilter to frequency domain symbol signal, MDFT unit adopts analysis filterbank structure; Described receiving terminal comprises: that removes prefix, equilibrium treatment acquisition mark signal to received signal removes prefix unit, equalizer; Knitting computing for carrying out reciprocal cross, computing being knitted to reciprocal cross and obtains the IMDFT unit acquisition mark signal that signal carries out MDFT inverse transformation, obtaining the reverse fast Fourier transform unit of transmitting terminal reconstruction signal for the mark signal of acquisition being carried out IFFT conversion.

11. systems according to claim 10, it is characterized in that, MDFT unit comprises, sub-band analysis filtration part: for carrying out pre-filtering to NM point frequency domain symbol signal, again according to prototype filter construction of function coefficient matrix H, with coefficient matrix H, the right side carried out to NM point frequency domain symbol signal multiplied to 2NM point frequency domain symbol signal; IFFT conversion fraction: obtain 2NM point time-domain signal for carrying out 2N M-point IFFT conversion to 2NM point frequency domain symbol signal; Intertexture arithmetic section: obtain NM point output complex symbol signal for carrying out intertexture computing to 2NM point time-domain signal.

12. modulating systems according to claim 10, is characterized in that, the reverse Fourier transform in described MDFT unit, and its reverse Fourier transform implemented is a reverse Fourier transform of 2N M-point.

13. systems according to claim 10, is characterized in that, described reverse fast Fourier transform unit, and its reverse fast Fourier transform implemented is the reverse fast Fourier transform of a NM-point, here N, M be more than or equal to 1 positive integer.

14. systems according to claim 10, it is characterized in that, described IMDFT unit, it is reduced to 2NM point frequency domain symbol signal for mark signal NM point being removed channel disturbance, post-filtering is carried out to 2NM point frequency domain symbol signal, then it is multiplied to NM point frequency domain symbol signal to carry out the right side according to the transpose pair 2NM point frequency domain symbol signal of coefficient matrix H.