A kind of overlapped time division multiplexing modulator approach, apparatus and system
Technical field
The present invention relates to the communications field, and in particular to a kind of overlapped time division multiplexing modulator approach, device and overlap
Time division multiplex system.
Background technology
So-called time division (hereinafter referred to as time-division) is multiplexed (TDM:Time Division Multiplexing)
It is that a kind of signal codes for allowing multiple to occupy narrower duration time in digital communication share a time wider
The technology of duration.It is as shown in Figure 1 the schematic diagram of conventional time-division multiplex technology.
Duration time (being referred to as time slot width in engineering) of the signal code that is respectively re-used in Fig. 1 is respectively
T1, T2, T3, T4 ..., them are generally allowed to occupy identical time slot width in engineering, Δ T is protected for minimum
Shield time slot, real protection time slot width should be well-to-do.Δ T should be greater than using the mistake of demultiplexing gate circuit
Cross maximum time amount of jitter of the time width plus system.This is most common time-division multiplex technology.It is existing exhausted
What the systems such as most multi-path digital broadcast system, multi-path digital communication were used is all this technology.
Maximum feature when this technology is applied to digital communication is multiplexed between signal code
It is completely insulated from each other, will never exists and interfere, the signal code to being re-used does not have any limitation,
The symbol duration (time slot width) of each signal can have different width, also can be suitably used for different communications
System, if their time slot do not overlap each other intersection just can be with, it is therefore most widely used.But this
Multiplexing is planted, multiplexing is like water off a duck's back to improving the spectrum efficiency of system in itself.
So, traditional viewpoint is not overlapped in time domain between adjacent channel, to avoid between adjacent channel
Produce interference, but the raising of spectrum efficiency of this limitation of the technology.The sight of the time-division multiplex technology of prior art
Point is not only need not be mutually isolated between each channel, and can have very strong overlapped, such as Fig. 2 institutes
Show, the overlap between channel is considered as a kind of new coding bound relation by prior art, and is closed according to the constraint
System proposes corresponding modulation and demodulation technology, therefore referred to as overlapped time division multiplexing (OvTDM:
Overlapped Time Division Multiplexing), this technology cause spectrum efficiency with overlap number of times K into
The increase of ratio.
In theory, when being carried out data transmission using overlapped time division multiplexing technology, overlapping number of times K can be ad infinitum
Increase, therefore spectrum efficiency also can ad infinitum increase, but had been found that in the laboratory research stage secondary with overlapping
The increase of number K, although spectrum efficiency is increased, but transimission power consequently also increases, and transimission power
Increase the increase that also limit to a certain extent overlap number of times K in turn, so as to also limit frequency spectrum effect
The increase of rate.
The content of the invention
The present invention provides a kind of overlapped time division multiplexing modulator approach, apparatus and system, solves initial Envelop waves
, when frequency domain bandwidth is wider, the waveform after overlapped time division multiplexing superposition is more precipitous in time domain, and frequency domain takes band for shape
It is wider, reduce the availability of frequency spectrum of whole system and the problem of transmission rate.
According to the application's in a first aspect, this application provides a kind of overlapped time division multiplexing modulator approach, including:
According to the design parameter generation initial envelope waveform that waveform is smoothed in time domain;
Initial envelope waveform is shifted in time domain by predetermined shift intervals according to overlapping multiplexing number of times,
To obtain the skew envelope waveform of each moment sending signal;
The digital signal sequences of input are converted into sign symbol sequence;
By the sign symbol sequence after conversion with skew after each moment sending signal skew envelope waveform phase
Multiply, to obtain the modulation envelope waveform at each moment;
The modulation envelope waveform at each moment is overlapped in time domain, to obtain carrying output signal sequence
Multiple modulation envelope waveform.
According to the second aspect of the application, present invention also provides a kind of overlapped time division multiplexing modulating device, bag
Include:
Waveform generating module, for according to the design parameter generation initial envelope waveform that waveform is smoothed in time domain;
Shift module, for initial envelope waveform to be pressed into predetermined displacement in time domain according to overlapping multiplexing number of times
Interval is shifted, to obtain the skew envelope waveform of each moment sending signal;
Modulation module, for the digital signal sequences of input to be converted into sign symbol sequence;
Multiplier module, for will be input into sign symbol sequence with offset after each moment sending signal it is inclined
Move envelope waveform to be multiplied, to obtain the modulation envelope waveform at each moment;
Laminating module, for the modulation envelope waveform at each moment to be overlapped in time domain, to be taken
Multiple modulation envelope waveform with output signal sequence.
According to the third aspect of the application, present invention also provides a kind of overlapped time division multiplexing modulation demodulation system,
Including transmitter and receiver;
The emitter includes:
Above-mentioned overlapped time division multiplexing modulating device, the multiple modulation Envelop waves of output signal sequence are carried for generating
Shape;
Emitter, for the multiple modulation envelope waveform to be transmitted into receiver;
The receiver includes:
Reception device, the multiple modulation envelope waveform for receiving the emitter transmitting;
Sequence detecting apparatus, for carrying out the data sequence detection in time domain to the multiple modulation envelope waveform for receiving,
To make decisions output.
In overlapped time division multiplexing modulator approach, apparatus and system that the present invention is provided, due to initial envelope waveform
Time domain waveform it is smoother, frequency domain bandwidth is narrower, and the waveform after superposition is smoother and is limited in narrower bandwidth,
Therefore the availability of frequency spectrum and transmission rate of system are improve, the bit error rate of system is reduced.
Brief description of the drawings
Fig. 1 is the schematic diagram of conventional time-division multiplex technology;
Fig. 2 is overlap time division multiplexing principle schematic diagram;
Fig. 3 is the structural representation of overlapped time division multiplexing system in an embodiment of the present invention;
Fig. 4 is the structural representation of overlapped time division multiplexing modulating device in an embodiment of the present invention;
Fig. 5 is the hardware architecture diagram of overlapped time division multiplexing modulating device in an embodiment of the present invention;
Fig. 6 is the structural representation of receiver pretreatment unit in an embodiment of the present invention;
Fig. 7 is the structural representation of receiver sequence detecting apparatus in an embodiment of the present invention;
Fig. 8 is the time domain waveform and frequency-domain waveform figure of Chebyshev's envelope waveform in an embodiment of the present invention;
Fig. 9 is the envelope waveform figure at Chebyshev window shifted rear each moment in an embodiment of the present invention;
The superposition of waveform to be sent is shown when Figure 10 is in an embodiment of the present invention using Chebyshev's envelope waveform
It is intended to;
Figure 11 is the principle schematic of K roads waveform multiplexing;
Figure 12 is the symbol additive process principle schematic of K roads waveform;
The Input output Relationship tree graph of overlapped time division multiplexing system when Figure 13 is K=3;
Figure 14 is node state transfer relationship figure;
Figure 15 is the time domain and frequency-domain waveform figure of square wave;
Figure 16 is the waveform after envelope waveform selects each signal generated during square wave envelope waveform and is superimposed
Figure;
Figure 17 is the time domain waveform and frequency domain of Blacknam first derivative envelope waveform in an embodiment of the present invention
Oscillogram;
Figure 18 is the time domain ripple of Blacknam-Harris's first derivative envelope waveform in an embodiment of the present invention
Shape and frequency-domain waveform figure;
Waveform to be sent when Figure 19 is in an embodiment of the present invention using Blacknam first derivative envelope waveform
Superposition schematic diagram;
Treated when Figure 20 is in an embodiment of the present invention using Blacknam-Harris's first derivative envelope waveform
Send the superposition schematic diagram of waveform.
Specific embodiment
The present invention is described in further detail below by specific embodiment combination accompanying drawing.
In to overlapping time-division multiplex technology research, inventor has found that the growth of transimission power is main with being re-used
The frequency spectrum of signal (modulating window function) is relevant, not as contemplated by theory to multiplexed signals frequency spectrum
Shape, bandwidth have no requirement.Although there are many window functions in the prior art, can freely adopt in theory
With various window functions to transmission symbol be modulated, but due to rectangular window compared to other window functions produce,
Design and application it is upper be easier, cost it is lower, therefore preferentially use rectangular window when signal modulation is carried out at present,
And the spectral bandwidth of square wave is wider, multiplexing waveform systematic function is very poor, causes required transimission power and mistake
Code check is all very high.
Based on above-mentioned discovery, in embodiments of the present invention, in application overlapped time division multiplexing technology using one kind
Window function better than square wave is modulated to the digital signal sequences being input into.
Fig. 3 is refer to, overlapped time division multiplexing system includes signal transmitter A01 and receiver A02.
Emitter A01 includes overlapped time division multiplexing modulating device 101 and emitter 102.Overlap the time-division multiple
It is used to generate the multiple modulation envelope waveform for carrying output signal sequence with modulating device 101;Emitter 102
For the multiple modulation envelope waveform to be transmitted into receiver A02.
Receiver A02 includes reception device 201 and sequence detecting apparatus 202.Reception device 201 is used to connect
The multiple modulation envelope waveform of the transmitting-receiving transmitting of injection device 102;Sequence detecting apparatus 202 are used for the polyphony to receiving
Envelope waveform processed carries out the data sequence detection in time domain, to make decisions output.
Preferably, receiver A02 also includes being arranged between reception device 201 and sequence detecting apparatus 202
Pretreatment unit 203, receive digital signal sequences for aiding in forming the synchronous of each frame in.
In emitter A01, the digital signal sequences of input pass through the shape of overlapped time division multiplexing modulating device 101
Into the overlapped transmission signal in time domain of multiple symbols, then the transmission signal is sent out by emitter 102
It is mapped to receiver A02.The signal of the transmitting of 201 receiving and transmitting unit of reception device 102 of receiver A02,
Forming suitable sequence detecting apparatus 202 by pretreatment unit 203 detect the data signal of reception, sequence
The docking collection of letters number of row detection means 202 carries out the data sequence detection in time domain, so as to export judgement.
Fig. 4 is refer to, overlapped time division multiplexing modulating device 101 (OvTDM modulating devices) is given birth to including waveform
Into module 301, shift module 302, multiplier module 303 and laminating module 304.
Waveform generating module 301 is used for according to the design parameter generation initial Envelop waves that waveform is smoothed in time domain
Shape.
Shift module 302 is used to that initial envelope waveform to be pressed into predetermined shifting in time domain according to overlapping multiplexing number of times
Bit interval is shifted, to obtain the skew envelope waveform of each moment sending signal.
Modulation module 305 is used to for the digital signal sequences of input to be converted into sign symbol sequence.
Multiplier module 303 is used for each moment sending signal after the sign symbol sequence after conversion and skew
Skew envelope waveform is multiplied, to obtain the modulation envelope waveform at each moment.
Laminating module 304 is used to be overlapped the modulation envelope waveform at each moment in time domain, to obtain
Carry the multiple modulation envelope waveform of output signal sequence.
With reference to overlapped time division multiplexing modulator approach, overlapped time division multiplexing modulating device 101 is done further
Illustrate, overlapped time division multiplexing modulator approach includes below step:
(1) waveform generating module 301 generates the smooth initial Envelop waves of waveform in time domain according to design parameter
Shape h (t).
When initial envelope waveform is generated, can be by user input design parameter, to realize in real system
It is middle according to system performance index flexible configuration.
In certain embodiments, when the side lobe attenuation of initial envelope waveform has determined, design parameter includes
The window length L of initial envelope waveform, such as when initial envelope waveform is Bart's Lay spy's envelope waveform.
In certain embodiments, design parameter includes the window length L and side lobe attenuation r of initial envelope waveform, example
Such as when initial envelope waveform is Chebyshev's envelope waveform.
Certainly, when initial envelope waveform is other forms, can be according to the characteristics of corresponding initial envelope waveform
Determine design parameter.
(2) initial envelope waveform is pressed predetermined by shift module 302 according to overlapping multiplexing number of times K in time domain
Shift intervals are shifted, to obtain the skew envelope waveform h (t-i* △ T) of each moment sending signal.
Wherein, shift intervals are for time interval △ T, time interval △ T:△ T=L/K.
In addition, in addition it is also necessary to ensure inverses of the △ T not less than systematic sampling rate.
The value of i is relevant with incoming symbol length N, and i takes 0 to N-1 integer.For example, working as N=8
When, i takes 0 to 7 integer.
(3) digital signal sequences of input are converted into sign symbol sequence by modulation module 305.
Specifically, 0 in the digital signal sequences of input is converted to+A by modulation module 305,1 is converted to-A,
A values are non-zero Arbitrary Digit, to obtain sign symbol sequence.For example, take A for 1 when, will be input into { 0,1 }
Bit sequence by BPSK (Binary Phase Shift Keying, phase-shift keying) modulation conversions into+1,
- 1 } symbol sebolic addressing.
(4) multiplier module 303 is by the sign symbol sequence x after conversioniWith each moment sending signal after skew
Skew envelope waveform h (t-i* △ T) be multiplied, to obtain the modulation envelope waveform x at each momenti h(t-i*△T)。
(5) laminating module 304 is by the modulation envelope waveform x at each momentiH (t-i* △ T) is folded in time domain
Plus, to obtain carrying the multiple modulation envelope waveform of output signal sequence, that is, the signal for sending.
The signal of transmission can be expressed as below:
Because the time domain waveform of initial envelope waveform is smoother, frequency domain bandwidth is narrower, and the waveform after superposition is relatively put down
Slide and be limited in narrower bandwidth, therefore improve the availability of frequency spectrum and transmission rate of system, reduce system
The bit error rate.
Fig. 5 is refer to, specifically, overlapped time division multiplexing modulating device 101 can be realized by following hardware cell.
Overlapped time division multiplexing modulating device 101 includes digital waveform generator 401, shift register 402, modulator
403rd, multiplier 404 and adder 405.
First cophase wave of initial envelope waveform is formed by digital waveform generator 401 in a digital manner first
Shape, the initial envelope waveform is smoothed in time domain;Again by shift register 402 by digital waveform generator 401
The phase wiggles of the first initial envelope waveform for producing are shifted, to produce each moment sending signal
Skew envelope waveform;Then, the digital signal sequences of input are converted into sign symbol sequence by modulator 403,
Multiplier 404 is then by the skew envelope of each moment sending signal after the sign symbol sequence after conversion and skew
Waveform is multiplied, to obtain the modulation envelope waveform at each moment;It is last by adder 405 by each moment
Modulation envelope waveform is overlapped in time domain, to obtain carrying the multiple modulation envelope waveform of output signal sequence,
Form transmission signal.
Fig. 6 is refer to, is the block diagram of the pretreatment unit 203 of receiver A02 in the embodiment of the present invention.
Pretreatment unit 203 includes synchronizer 501, channel estimator 502 and digital processor 503.Its
The docking collection of letters number of middle synchronizer 501 forms a symbol time synchronization in receiver;Then channel estimator 502
Channel parameter is estimated;Digital processor 503 is digitized place to the reception signal of each frame in
Reason, so that forming suitable sequence detecting apparatus carries out the digital signal sequences of Sequence Detection reception.
Fig. 7 is refer to, is the block diagram of the sequence detecting apparatus 202 of receiver A02 in the embodiment of the present invention.
Sequence detecting apparatus 202 include that analytic unit memory 601, comparator 602 and multiple surviving paths are deposited
Reservoir 603 and Euclidean distance memory 604 or weighted euclidean distance memory (not shown).In detection
During, the complex convolution encoding model that analytic unit memory 601 makes overlapped time division multiplexing system is passed
Shape figure, and whole states of overlapped time division multiplexing system are listed, and store;And comparator 602 is according to analysis
Trellis structure in cell memory 601, searches out and receives data signal minimum Eustachian distance or weighting minimum
The path of Euclidean distance;And surviving path memory 603 and Euclidean distance memory 604 or weighted Euclidean away from
Then be respectively used to store from memory the surviving path and Euclidean distance or weighted Euclidean of the output of comparator 602 away from
From.Wherein, surviving path memory 603 and Euclidean distance memory 604 or weighted euclidean distance memory
Need respectively to prepare one for each stable state.The length of surviving path memory 603 can be preferably 4K~
5K.Euclidean distance memory 604 or weighted euclidean distance memory are preferably only storage relative distance.
The initial envelope waveform used in overlapped time division multiplexing modulator approach, apparatus and system can include cutting ratio
Snow husband (Chebyshev), Gauss (Gaussian), Hamming (Hamming), the Chinese peaceful (Hann), Bu Lai
Ke Man (Blackman), Blacknam-Harris (Blackman-Harris), Bart Lai Te (Bartlett),
Bart Lai Te-Han Ning (Bartlett-Hanning), Berman (Bohman), flat-top (Flat Top), Nuttall
(Nuttall), Ba Ersen (Parzen), Taylor (Taylor), figure base (Tukey), kayser (Kaiser),
Triangle (Triangular) etc. is multiplexed waveform and the differentiation waveform based on it.
It is then multiple with Chebyshev, Blacknam first derivative and Blacknam-three kinds of Harris's first derivative below
The application is described further with waveform.
Embodiment one
The present embodiment is Chebyshev's envelope waveform with initial envelope waveform, and overlapping multiplexing number of times K=3 is input into
Symbol lengths N=8, incoming symbol xiThe signal of OvTDM is illustrated as a example by={+1+1-1-1-1+1-1+1 }
Send and receive process.Wherein, incoming symbol length refers to the length for sending a frame signal.
Fig. 5 is refer to, signal generation process includes below step:
(1) Chebyshev's envelope waveform h (t) of sending signal is generated according to design parameter first.
In the present embodiment in design parameter, window length L=63, side lobe attenuation r=80dB, its time domain waveform and
Frequency-domain waveform is as shown in Figure 8.As can be seen from Figure 8, Chebyshev window is by approximate 0 in time domain waveform
Point starts, and frequency domain side lobe decays to 80dB.
(2) Chebyshev's envelope waveform h (t) designed by (1) is pressed into predetermined shift intervals in time domain
Shifted, wherein, shift intervals are time interval △ T (△ T=L/K=21).After displacement, form each
(due to N=8, therefore i is integer and value is for the skew envelope waveform h (t-i* △ T) of individual moment sending signal
0~7), the skew envelope waveform figure of each moment sending signal is as shown in Figure 9 after displacement.
(3) digital signal sequences of input are converted into sign symbol sequence.
Specifically, 0 in the digital signal sequences of input can be converted into+A, 1 is converted to-A, A takes
It is non-zero Arbitrary Digit to be worth, to obtain sign symbol sequence.For example, take A for 1 when, will be input into { 0,1 } ratio
Special sequence is by BPSK modulation conversions into {+1, -1 } symbol sebolic addressing.
(4) by sign symbol sequence xi(x in the present embodimenti={+1+1-1-1-1+1-1+1 }) and (2)
The skew envelope waveform h (t-i* △ T) of each moment sending signal of generation is multiplied, and obtains the modulation at each moment
Envelope waveform xih(t-i*△T);Waveform after formation is as shown in Figure 10, wherein three different dotted lines represent phase
Three oscillograms after multiplying.
(5) the modulation envelope waveform x at each moment for being formed (4)iH (t-i* △ T) is carried out in time domain
Superposition, to obtain carrying the multiple modulation envelope waveform of output signal sequence, that is, the signal for sending.Transmission signal
Oscillogram is as shown in the solid line waveform in Figure 10.
The signal of transmission can be expressed as:
Specifically, output signal sequence is determined by following mode:
When modulation envelope waveform is multiplied by plus sign with the moment envelope waveform to be obtained, the modulation envelope ripple is made
The operation values of shape are+A, when modulation envelope waveform is multiplied by minus symbol with the moment envelope waveform to be obtained, order
The operation values of the modulation envelope waveform are-A.For each shift intervals, the tune in the shift intervals will be located at
The operation values superposition of envelope waveform processed, draws the output signal of the shift intervals, so as to form output signal sequence
Row.
Therefore, in the present embodiment, when A values are 1, the output symbol (output signal sequence) after superposition is
For:S (t)={+1+2+1-1-3-1-1+1 }.
Figure 11 is refer to, is the principle schematic of K roads waveform multiplexing, its parallelogram shape.Wherein,
A symbol x to be sent is represented per a lineiObtained after being multiplied with the envelope waveform h (t-i* △ T) at corresponding moment
Signal waveform x to be sentih(t-i*△T)。a0~ak-1Expression is carried out to each window function waveform (envelope waveform)
The coefficient value for being segmented the every part for obtaining K times, the specially coefficient on range value.
During due to the digital signal sequences of input being converted into sign symbol sequence, the data signal sequence that will be input into
In row 0,1 is converted to ± A, and A values are non-zero Arbitrary Digit to obtain sign symbol sequence.For example, A takes
Be worth for 1 when, will be input into { 0,1 } bit sequence by BPSK modulation conversions into {+1, -1 } symbol sebolic addressing,
To obtain sign symbol sequence.So being the symbol additive process principle schematic of K roads waveform shown in Figure 12.
In Figure 12 additive processes, the number of the 1st row left side 3 represents the 1st incoming symbol+1, the 2nd 3, the row left side
Number represents the 2nd incoming symbol+1, and the number of the 3rd row left side 3 represents the 3rd incoming symbol -1st, the 1st row
Middle 3 numbers represent that 3 numbers represent the 5th incoming symbol -1st in the middle of the 4th incoming symbol -1st, the 2nd row,
3 numbers represent the 6th incoming symbol+1 in the middle of 3rd row, and 3 numbers of the 1st row the right represent the 7th input
Symbol -1,3 numbers of the 2nd row the right represent the 8th incoming symbol+1.Therefore, after three addition of waveforms,
The output symbol for obtaining is {+1+2+1-1-3-1-1+1 }.
Certainly, if the length of incoming symbol is other numerical value, can be according to shown in Figure 11 and Figure 12
Mode is overlapped, to obtain output symbol.
Due to Chebyshev's envelope waveform time domain by 0 (0.0028, close to 0) starting, with smooth ripple
Waveform after shape, therefore superposition is smoother, and frequency domain bandwidth is narrower so that waveform frequency spectrum efficiency after superposition compared with
Height, the transimission power needed for sending signal is relatively low.Again because Chebyshev's envelope waveform can be with designed, designed by
Valve is decayed, therefore in systems in practice can be according to system performance index flexible configuration.
Fig. 6 and Fig. 7 is refer to, signal receives process includes below step:
(1) the docking collection of letters number first is synchronized, including the synchronization of carrier synchronization, frame synchronization, symbol time etc..
(2) according to sampling theorem, the reception signal to each frame in is digitized treatment.
(3) waveform for receiving is cut according to waveform transmission time interval.
(4) the data sequence detection in time-domain is carried out to the signal for receiving, to make decisions output, that is, is pressed
Row decoding is entered to the waveform after cutting according to certain decoding algorithm.
By after the pre-treatment step of above-mentioned (1)~(2), the reception symbol sebolic addressing obtained after waveform cutting is:
S (t)={+1+2+1-1-3-1-1+1 }, to symbol sebolic addressing according to the tree graph and figure of Fig. 7 Input output Relationships
8 node state transfer relationship figures, carry out between symbol before and after compare, obtain node transfer path.
In Figure 13, upward branch is+1 input, and downward branch is -1 input.The tree after the 3rd
Figure reforms into repetition, because the branch that every node from labeled as a gives off has same output,
The conclusion is equally applicable to node b, c, d.They nothing more than being several possibility as shown in figure 14, from
It can be seen that (through input+1) node a and (through input -1) node b can only be transferred to from node a in Figure 14, together
When b can only arrive (input+1) c and (input -1) d, c and can only arrive (input+1) a and (being input into -1) b, d can only arrive (defeated
Enter+1) c and (input -1) d.The reason for producing this phenomenon is very simple, because only that adjacent K is (specific to this example
It is that 3) individual symbol can just be formed and interfered.So when K data are input to channel, for coming earliest
1 data has moved out a shift unit of rightmost.Therefore the output of channel is except depending on current moment
The input of data, further depends on the input of preceding K-1 data.
Such as blackening shown in thick line in Figure 13, first due to s (t) accords with for node state transfer in present case
Number be+1, so node transfer path is:+1->a->a->b->d->d->c->b->C, according to this turn
The symbol sebolic addressing that shifting relation can obtain input is {+1+1-1-1-1+1-1+1 }.
In the present embodiment, because Chebyshev's envelope waveform is smoother in time domain, and side lobe attenuation is very fast,
Therefore the transimission power needed for is relatively low, and precision is higher when being cut to waveform, and the symbol sebolic addressing for receiving is accurate
Exactness is more preferable.
Figure 15 is refer to, is the time domain and frequency-domain waveform figure of square wave.When initial envelope waveform selects square wave
During envelope waveform, then the oscillogram after each signal generated according to above-mentioned signal generation process and superposition is such as
Shown in Figure 16, wherein three different dotted lines represent three oscillograms, solid line represents the oscillogram after superposition.
As can be seen from Figure 16, square wave in time domain by 1, and broader bandwidth, on frequency domain
Side lobe attenuation is slow, therefore waveform after time domain superposition is unsmooth, and frequency domain bandwidth is wider, useful signal and nothing
Effect signal is difficult to differentiate between so that transimission power required during sending and receiving signal increases, and receives letter
The accuracy rate of waveform cutting and coding/decoding capability reduction during number.In systems in practice transmission rate it is identical and
In the case of spectrum efficiency identical, required transimission power and the bit error rate are all very high during using square wave.
But the Chebyshev window used in the present embodiment time domain starting point by 0 (0.0028, close to 0) opening
Begin, side lobe attenuation is very fast, the waveform after Signal averaging is smoothed, and frequency domain bandwidth is narrower, improve waveform cutting
The accuracy rate of process and the error correcting capability of encoding-decoding process, reduce the transimission power of signal so that in frequency spectrum
The timing of efficiency one, transmission rate higher can be just reached using relatively low transimission power.Again because Chebyshev
Window can be with designed, designed side lobe attenuation, therefore in systems in practice can be according to system performance index flexible configuration.
In addition, in other embodiments, initial envelope waveform is also an option that various with Chebyshev's window function
The envelope waveform of the function of differentiation, including the company of Chebyshev's pulse-shaping multiply, all-order derivative, all-order derivative
The envelope waveform of the functions such as sum, these envelope waveforms in time domain it is same with waveform it is smooth the characteristics of, because
This using can be reached after these envelope waveforms with using the close effect of Chebyshev's envelope waveform.
Embodiment two
The present embodiment is respectively Blacknam first derivative, Blacknam-Harris's single order with initial envelope waveform
Derivative is multiplexed waveform, overlapping multiplexing number of times K=3, incoming symbol length N=8, incoming symbol xi={+1+1-1
- 1-1+1-1+1 } illustrate that the signal of OvTDM sends and receives process as a example by.
Fig. 5 is equally refer to, signal generation process includes below step:
(1) Blacknam first derivative, the Blacknam-Harry of sending signal are generated according to design parameter first
Corresponding envelope waveform h (t) of this first derivative.
Window length L=63 in the present embodiment in design parameter, its corresponding time domain waveform and frequency-domain waveform are distinguished
As shown in Figure 17 and Figure 18.
As can be seen from Figure 17, the envelope waveform of Blacknam first derivative is in the time domain by approximate 0 point
Start, negative is changed into latter half amplitude, waveform levels off to sine wave, and it is left that frequency domain side lobe decays to 40dB
It is right.
As can be seen from Figure 18, the envelope waveform of Blacknam-Harris's first derivative is in the time domain by near
Start like 0 point, negative is changed into latter half amplitude, waveform levels off to sine wave, frequency domain side lobe is decayed to
100dB or so.
Specifically, for Blackman window function, it can be represented by formula below:
ω (n)=0.42-0.5cos (2 π n/ (N-1))+0.08cos (4 π n/ (N-1))
Wherein, N be window length, 0≤n≤M-1, when N be even number when, M=N/2, when N be odd number when,
M=(N+1)/2.
It should be noted that in due to above-mentioned formula, 0≤n≤M-1, that is, the waveform for obtaining is distributed for first half
The graceful window in Rec, for the waveform (i.e. during M≤n≤N-1) of latter half Blackman window, itself and first half
Point waveform with straight line n=M axisymmetricly, will first half waveform along straight line n=M flip horizontals after
Obtain.
Specifically, for Blackman-Harris window function (symmetric function), it can be represented by formula below:
ω (n)=a0-a1cos (2 π n/ (N-1))+a2cos (4 π n/ (N-1))+a3cos (6 π n/ (N-1))
For Blackman-Harris window function (periodic function), it can be represented by formula below:
ω (n)=a0-a1cos2 π n/N+a2cos4 π n/N+a3cos6 π n/N
Wherein, N be window length, 0≤n≤N-1, a0=0.35875, a1=0.48829, a2=0.14128,
A3=0.01168.It should be noted that the function variable in n only representation formulas in above-mentioned formula.
(2) by the Blacknam first derivative designed by (1), Blacknam-Harris's first derivative envelope
Waveform h (t) is shifted in time domain by predetermined shift intervals, wherein, shift intervals are time interval △ T
(△ T=L/K=21).After displacement, the skew envelope waveform h (t-i* △ T) of each moment sending signal is formed
(due to N=8, thus i be integer and value be 0~7).
(3) digital signal sequences of input are converted into sign symbol sequence.
Specifically, in the digital signal sequences that will can be input into 0,1 is converted to ± A, A values are non-zero
Meaning number, to obtain sign symbol sequence.For example, when A values are 1, { 0,1 } bit sequence warp that will be input into
Cross BPSK modulation conversions into {+1, -1 } symbol sebolic addressing.
(4) by sign symbol sequence xi(x in the present embodimenti={+1+1-1-1-1+1-1+1 }) in symbol
Number skew envelope waveform h (t-i* △ T) of each moment sending signal generated with (2) is multiplied, when obtaining each
The modulation envelope waveform x at quarterih(t-i*△T);Waveform after formation respectively as shown in Figure 19,20, wherein three
Different dotted lines represents three oscillograms after being multiplied.
(5) the modulation envelope waveform x at each moment for being formed (4)iH (t-i* △ T) is carried out in time domain
Superposition, to obtain carrying the multiple modulation envelope waveform of output signal sequence, that is, the signal for sending.Transmission signal
Oscillogram is respectively as shown in the solid line waveform in Figure 19 and Figure 20.
The signal of transmission can be expressed as:
Specifically, output signal sequence is determined by following mode:
When modulation envelope waveform is multiplied by plus sign with the moment envelope waveform to be obtained, the modulation envelope ripple is made
The operation values of shape are+A, when modulation envelope waveform is multiplied by minus symbol with the moment envelope waveform to be obtained, order
The operation values of the modulation envelope waveform are-A.For each shift intervals, the tune in the shift intervals will be located at
The operation values superposition of envelope waveform processed, draws the output signal of the shift intervals, so as to form output signal sequence
Row.
Therefore, in the present embodiment, when A values are 1, the output symbol (output signal sequence) after superposition is
For:S (t)={+1+2+1-1-3-1-1+1 }.
Initial envelope waveform is respectively Blacknam first derivative, Blacknam-Harris's first derivative multiplexing ripple
During shape, waveform principle of multiplexing is shown and symbol additive process principle is identical with embodiment one, refer to the He of accompanying drawing 11
Figure 12.
In the present embodiment, signal receive process with embodiment one using Chebyshev's envelope waveform when signal connect
Receipts process is identical, therefore, the present embodiment is repeated no more.
Because Blacknam first derivative, Blacknam-Harris's first derivative are multiplexed waveform and are relatively put down in time domain
Sliding, and side lobe attenuation is very fast therefore required transimission power is relatively low, and precision is higher when being cut to waveform,
The symbol sebolic addressing degree of accuracy for receiving is more preferable.
The characteristics of square wave is that main lobe compares concentration, has the disadvantage that secondary lobe is higher, and has negative secondary lobe, causes conversion
In brought High-frequency Interference and leakage into, or even there is negative frequency spectrum phenomenon, amplitude accuracy of identification is minimum.Cloth Rec
The characteristics of graceful first derivative and Blacknam-Harris's first derivative multiplexing waveform is main lobe wide, secondary lobe than relatively low,
Amplitude accuracy of identification highest, there is more preferable selectivity.
Take Blacknam first derivative, Blacknam-Harris's first derivative as the OvTDM mistakes for being multiplexed waveform
Journey, in signal transmission process, time domain waveform is smoothed, and frequency domain bandwidth is narrower, the transmission work(needed for sending signal
Rate is relatively low, and the availability of frequency spectrum and transmission rate are all higher.In reception signal process, because waveform is in time domain
It is smoother, therefore when being cut to waveform, the degree of accuracy is higher, reduces the bit error rate of system.Systematic function compared with
Square wave is greatly improved.
In addition, in other embodiments, initial envelope waveform is also an option that various Blackman window prototypes,
Or with Blackman window function develop other functions envelope waveform, including Blacknam pulse-shaping company
Multiply, the envelope waveform of the function such as all-order derivative, all-order derivative sum, using after these envelope waveforms can be with
Reach the effect close with Blacknam waveform first derivative is used.
Or, initial envelope waveform selects various Blackman-Harris window prototypes, or with Blacknam-Harry
This window function develop other functions envelope waveform, including the company of Blacknam-Harris's pulse-shaping multiply,
The envelope waveform of the functions such as all-order derivative, all-order derivative sum, these envelope waveforms equally have in time domain
The characteristics of waveform is smoothed, thus using can be reached after these envelope waveforms and use Blacknam-Harris
The close effect of waveform first derivative.
The present invention provide overlapped time division multiplexing modulator approach, apparatus and system due to initial envelope waveform when
Smoothed in domain so that the waveform after superposition is smoothed, so that the transimission power of system linearly slowly increases,
Connect and improve the availability of frequency spectrum and transmission rate.The overlapped time division multiplexing modulator approach, apparatus and system can be with
It is applied to mobile communication, satellite communication, microwave horizon communication, scatter communication, atmosphere optic communication, infrared
In the wireless communication systems such as communication, underwater sound communication, Large Copacity was both can apply to and had been wirelessly transferred, it is also possible to should
For the light-duty radio system of low capacity.
It will be understood by those skilled in the art that all or part of step of various methods can in above-mentioned implementation method
To instruct related hardware to complete by program, the program can be stored in a computer-readable recording medium,
Storage medium can include:Read-only storage, random access memory, disk or CD etc..
Use above specific case is illustrated to the present invention, is only intended to help and understands the present invention, not
It is used to limit the present invention.For those skilled in the art, according to thought of the invention,
Some simple deductions, deformation can also be made or replaced.