CN100550876C - A kind of telecommunication system transceiver in transform domain and its implementation - Google Patents
A kind of telecommunication system transceiver in transform domain and its implementation Download PDFInfo
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- CN100550876C CN100550876C CNB2006100667097A CN200610066709A CN100550876C CN 100550876 C CN100550876 C CN 100550876C CN B2006100667097 A CNB2006100667097 A CN B2006100667097A CN 200610066709 A CN200610066709 A CN 200610066709A CN 100550876 C CN100550876 C CN 100550876C
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Abstract
The invention discloses a kind of telecommunication system transceiver in transform domain and its implementation, transform domain communication system (TDCS of the present invention, Transform Domain Communication System) transmitter is after frequency domain is modulated to sent data, launch the data-signal after this modulation through OFDM (OFDM, Orthogonal FrequencyDivision Multiplexing) transmitter; The TDCS receiver receives data-signal through the OFDM receiver, and obtains the data that the TDCS transmitter sends by demodulation.The present invention program has realized the TDCS transceiver simply, has improved the antijamming capability of equipment, has reduced the cost of equipment simultaneously.
Description
Technical field
The present invention relates to transform domain communication system (TDCS, Transform Domain CommunicationSystem), refer to a kind of telecommunication system transceiver in transform domain and its implementation especially.
Background technology
The basic thought of TDCS is by dynamically change the frequency spectrum that transmits in given spectral range, to avoid the existing subscriber to this interference that transmits, and avoid this to transmit to existing subscriber's interference.
Usually, in the TDCS transmitter, cyclic shift keying modulation (CCSK, Cyclic CodeShift Keying) is used in modulation, and CCSK is a kind of M system modulation system.The implementation of the simplest CCSK modulation is, selects a basic function (Base Function) b (t) earlier, according to the data that will send basic function done cyclic shift then, sends the basic function through cyclic shift at last.
Fig. 1 is the TDCS transmitter composition frame chart of prior art based on Fourier transform, as shown in Figure 1, the TDCS transmitter based on Fourier transform comprises following functional module: spectrum estimation (EstimateSpectrum) module, idle frequency spectrum mark (Spectrum Magnitude) module, random phase generate (Random Phase) module, convergent-divergent (Scale) module, inverse discrete Fourier transformer inverse-discrete (IDFT) module, storage (Memory) module, modulation (Modulation) module, transmission (Transmitter) module and finish the multiplier of multiplication function.
Wherein, the spectrum estimation module is used for determining glitch-free spectral regions.The method of determining can be periodogram well known in the art, autoregression figure or based on the technology of small echo etc.;
Which frequency free time the idle frequency spectrum mark module is used for determining in the communication channel, and which frequency is occupied.The method of determining preestablishes a spectrum amplitude threshold value normally according to the average power signal in the channel spectrum scope, obtains the spectrum estimation value by spectrum estimation; Relatively spectrum estimation value and this spectrum amplitude threshold value will be set at 0 occupiedly to represent above the frequency of this spectrum amplitude threshold value, will not be set at 1 representing the free time above the frequency of this spectrum amplitude threshold value, thus generation spectrum amplitude sequence A (ω);
The random phase generation module is used to generate a many-valued multiple random phase sequence e
J θ (ω), this multiple random phase sequence e
J θ (ω)Be used for phase randomization, promptly realize scrambling amplitude sequence A (ω).Multiple random phase sequence e
J θ (ω)Multiply each other through multiplier with spectrum amplitude sequence A (ω) corresponding element and to obtain complex sequences B
b(ω);
Zoom module such as power amplifier are used for complex sequences B
b(ω) carry out the amplitude convergent-divergent, make all signals in the sequence B (ω) that obtains have identical energy, can make full use of power amplification efficiency like this;
The inverse discrete Fourier transformer inverse-discrete module is used for the sequence B (ω) of frequency domain is converted to the basic function b (t) of time domain.As seen, the basic function b (t) of generation only has energy in the spectral regions of free time;
Memory module is used to store the basic function b (t) of generation;
Modulation module is used for the basic function of memory module is modulated.TDCS uses the CCSK modulation, comes data signal d (t) by the different cyclic shifts of basic function; Because modulation is finished in time domain, need jumbo memory module to store intermediate data.
Sending module is used to send through the data-signal d of ovennodulation (t).
Correspondingly, Fig. 2 is the TDCS receiver composition frame chart of prior art based on Fourier transform, as shown in Figure 2, the TDCS receiver based on Fourier transform comprises following functional module: idle frequency spectrum mark module, random phase generation module, inverse discrete Fourier transformer inverse-discrete module, get conjugate module, correlation module, maximum likelihood decision module and finish the multiplier of multiplication function.
Wherein, which frequency free time the idle frequency spectrum mark module is used for determining in the communication channel, and which frequency is occupied, generates spectrum amplitude sequence A ' (ω);
The random phase generation module is used to generate a many-valued multiple random phase sequence e
J θ ' (ω), the multiple random phase sequence e of generation
J θ ' (ω)With the spectrum amplitude sequence A ' (ω) corresponding element multiplies each other through multiplier and obtains (ω) e of frequency domain vectors A '
J θ (ω)
The inverse discrete Fourier transformer inverse-discrete module is used for (ω) e with the vector A ' of frequency domain
J θ ' (ω)Be converted to the reference function c (t) of time domain;
Get conjugate module, be used for time domain reference function c (t) is carried out conjugate operation, then the reference function c (t) through conjugate operation is carried out equally spaced M cyclic shift, obtain M vector C
j(t), j=0 ..., M-1, wherein, M is the order of modulation that sets in advance, i.e. the number that transmitting terminal can the information transmitted concentrated message;
Correlation module is used for carrying out to the received signal related operation, is exactly a correlator usually.The data-signal d (t) from TDCS transmitter output that will receive by antenna is called data-signal r (t), and gets M vector C of conjugate module output in the TDCS receiver
j(t) input correlator after multiplier multiplies each other carries out related operation, obtains correlated results z
j(t);
The maximum likelihood decision module is used for from M correlated results z
j(t) find out the pairing subscript k of value of amplitude maximum in, k is a value among the j, promptly finds out cyclically shifted sequences c
k(t), thus obtain and cyclically shifted sequences c
k(t) estimated value of the data symbol of corresponding transmission
From above-mentioned existing based on Fourier transform the TDCS transceiver and its implementation as seen, for the TDCS transmitter,, need jumbo memory module store intermediate data because modulation is finished in time domain, increased the cost of equipment; For the TDCS receiver, need complicated correlator, improved the cost of equipment, and complicated related operation, prolonged the realization time of TDCS receiver.In addition, in the multipath transmission environment, when propagation delay surpasses the length of a chip, in order to utilize multipath signal to realize time diversity, need to adopt complicated Rake receiver to receive data-signal r (t), so that merge multipath signal, otherwise receiver performance will descend, the Rake receiver belongs to techniques well known, can be not described in detail here with reference to related data.
In addition, also have a kind of low intercepting and capturing rate telecommunication system transceiver scheme at present, similar to the TDCS transceiver scheme based on Fourier transform, low intercepting and capturing rate communication system transmitter is identical with TDCS transmitter based on Fourier transform, no longer repeats here; Low intercepting and capturing rate communication system receiver carries out fast fourier transform to the received signal, with conversion gained result be multiplied by independent that generate, with the multiple B of the employed sequence of low intercepting and capturing rate communication system transmitter
b(ω) Yi Yang complex sequences, remove the maximum in the gained result vector that multiplies each other then, will carry out fast fourier transform again to resulting vector at last, obtain adjudicating sequence, in the judgement sequence, search the pairing subscript of element of amplitude maximum, thereby obtain the estimated value of transmitted data symbols
Here, need carry out global search during judgement, and global search is a time-consuming process, and can search for element during global search without the CCSK modulation, when these elements are subjected to strong jamming, erroneous judgement will appear, increased the total probability of miscarriage of justice of receiving terminal.
Based on the implementation of existing two kinds of TDCS transceivers, the main problem that exists is the realization complexity of TDCS transceiver, thereby has reduced the antijamming capability of equipment, has also improved the cost of equipment.
Summary of the invention
In view of this, main purpose of the present invention is to provide a kind of telecommunication system transceiver in transform domain, can simple realization TDCS transceiver, improve the antijamming capability of equipment, and reduce the cost of equipment simultaneously.
Another object of the present invention is to provide a kind of implementation method of telecommunication system transceiver in transform domain, can simple realization TDCS transceiver, improve the antijamming capability of equipment, reduce the cost of equipment simultaneously.
For achieving the above object, technical scheme of the present invention specifically is achieved in that
A kind of transform domain communication system TDCS transceiver comprises TDCS transmitter and TDCS receiver,
The TDCS transmitter comprises: basic sequence generation unit, modulating unit and orthogonal frequency division multiplex OFDM transmitter,
Wherein, the basic sequence generation unit is used to generate basic sequence, comprising: spectrum estimation module, idle frequency spectrum mark module and random phase generation module,
Modulating unit, the data-signal to be sent that is used for receiving is mapped as the frequency domain data signal, receives the basic sequence from the basic sequence generation unit, and this basic sequence and frequency domain data signal be multiply by mutually realize cyclic shift keying CCSK modulation,
The OFDM transmitter is used for frequency domain data signal after the multiplying each other of automodulation unit in the future and carries out inverse discrete Fourier transformer inverse-discrete and obtain the time domain data signal, launches after adding Cyclic Prefix;
The TDCS receiver comprises: OFDM receiver, basic sequence generation unit and demodulating unit,
Wherein, the OFDM receiver, the time domain data signal that is used for the interpolation Cyclic Prefix that will receive removes Cyclic Prefix, and exports to demodulating unit after being converted to the frequency domain data signal,
The basic sequence generation unit is used to generate basic sequence, and the basic sequence that generates is exported to demodulating unit,
Demodulating unit is used for that the basic sequence that receives is got conjugation and obtains conjugate, calculates the conjugate of acquisition and the product of the frequency domain data signal that described OFDM receiver is converted to, and obtains receiving vector after removing random phase; Described reception vector is carried out inverse discrete Fourier transformer inverse-discrete obtain time domain reception vector; Described time domain is received vector get real part, obtain real part and receive vector; Receive the vector from described real part and to obtain the judgement sequence, in the judgement sequence, search the pairing subscript of amplitude maximum element, obtain the estimated value of the pairing described data-signal to be sent of this subscript.
The basic sequence generation unit of described TDCS receiver comprises: spectrum estimation module, idle frequency spectrum mark module and random phase generation module.
Described modulating unit comprises data map module and multiplier;
Described data map module receives data-signal to be sent, from the basic sequence of the basic sequence generation unit of described TDCS transmitter; The data-signal to be sent that receives is mapped as the frequency domain data signal, and after multiplying each other in described multiplier with basic sequence, exports to the OFDM transmitter from the basic sequence generation unit of described TDCS transmitter.
Described demodulating unit comprises: get conjugate module, invert fast fourier transformation module, get real part module, maximum subscript search module and multiplier;
Get conjugate module, reception is from the basic sequence of the basic sequence generation unit of TDCS receiver, and this basic sequence got conjugation, get basic sequence after the conjugation through multiplier and frequency domain data signal multiplication, and remove and export to the invert fast fourier transformation module after obtaining receiving vector after the random phase from described OFDM receiver;
The invert fast fourier transformation module, be used for will receive the reception vector carry out inverse discrete Fourier transformer inverse-discrete and obtain time domain and receive vector, and send to and get the real part module;
Get the real part module, be used for that the time domain that receives is received vector and get real part, obtain real part and receive vector, and send to maximum subscript search module;
Maximum subscript search module is used for receiving vector from the real part that receives and extracts the judgement sequence, searches the pairing subscript of amplitude maximum element in the judgement sequence, obtains the estimated value of the data-signal to be sent of this subscript correspondence.
The basic sequence generation unit of described TDCS transmitter also comprises: memory module is used to store the basic sequence that the basic sequence generation unit of described TDCS transmitter generates.
A kind of implementation method of transform domain communication system TDCS transceiver, this method comprises:
Transmitting terminal generates basic sequence, to obtain the frequency domain data signal after the data-signal mapping to be sent, the basic sequence of described frequency domain data signal and the generation of described transmitting terminal be multiply by realization cyclic shift keying CCSK modulation mutually, frequency domain data signal after the orthogonal frequency division multiplex OFDM transmitter will multiply each other is carried out inverse discrete Fourier transformer inverse-discrete and is obtained the time domain data signal, and to launching behind the time domain data signal interpolation Cyclic Prefix that obtains, the method that described transmitting terminal generates basic sequence is:
A1. determine noiseless spectral regions, and in this glitch-free spectral regions, generate the spectrum amplitude sequence;
A2. generate the random phase sequence, and obtain basic sequence according to the random phase sequence and the spectrum amplitude sequence that generate;
Receiving terminal receives the time domain data signal that adds Cyclic Prefix through the OFDM receiver, removes Cyclic Prefix and is converted to the frequency domain data signal; Receiving terminal generates basic sequence; The basic sequence that the receiving terminal that obtains is generated is got conjugation and is obtained conjugate, and calculates the product of the frequency domain data signal that the conjugate that obtains and described receiving terminal be converted to, and obtains receiving vector after removing random phase; Described reception vector is carried out inverse discrete Fourier transformer inverse-discrete obtain time domain reception vector; Described time domain is received vector get real part, obtain real part and receive vector; Receive the vector from described real part and to obtain the judgement sequence, in the judgement sequence, search the pairing subscript of amplitude maximum element, obtain the estimated value of the pairing described data-signal to be sent of this subscript.
In the steps A 2, the described method of obtaining basic sequence is: the product that calculates described random phase sequence and spectrum amplitude sequence corresponding element.
The method that described receiving terminal generates basic sequence is:
B1. generate the random phase sequence, and obtain basic sequence according to the random phase sequence and the spectrum amplitude sequence that generate.
As seen from the above technical solution, TDCS transmitter of the present invention after frequency domain is modulated to sent data, the data-signal after the OFDM transmitter is launched this modulation; The TDCS receiver receives data-signal through the OFDM receiver, and by after OFDM receiver and the invert fast fourier transformation realization demodulation, obtains the data that the TDCS transmitter sends.From the present invention program as seen, the TDCS transmitter, helps and existing OFDM technical compatibility by using ripe OFDM transmitter techniques based on the OFDM transmitter, such as the inverse discrete Fourier transformer inverse-discrete function that can directly utilize in the OFDM transmitter, and after conversion, add Cyclic Prefix etc.; Adopt OFDM receiver and inverse discrete Fourier transformer inverse-discrete to realize demodulation, avoided complicated correlator, thereby make that the TDCS transceiver implementation that the present invention is based on OFDM is simple; In addition, carrying out message transmission with direct use OFDM transmitter compares, owing to transmit is to adopt the CCSK modulation on randomized spectrum amplitude sequence, and randomized spectrum amplitude sequence generally all is the lower sequence of peak-to-average ratio value, therefore, the present invention is based on the data-signal that the TDCS transmitter of OFDM sends lower peak-to-average ratio value is arranged; In fading channel and multipath propagation environment, because receiver uses the OFDM technology, channel estimating realizes easily, thereby avoided complicated Rake receiver, makes and realizes becoming simpler; By dwindling solid part signal Vector search scope is order of modulation M the point that only search sets in advance, rather than global search, has improved the performance of search speed and communication system.
Description of drawings
Fig. 1 is the TDCS transmitter composition frame chart of prior art based on Fourier transform;
Fig. 2 is the TDCS receiver composition frame chart of prior art based on Fourier transform;
Fig. 3 is the TDCS transmitter composition frame chart that the present invention is based on OFDM;
Fig. 4 is the TDCS receiver composition frame chart that the present invention is based on OFDM.
Embodiment
Core concept of the present invention is: the TDCS transmitter after frequency domain is modulated to sent data, the data-signal after the OFDM transmitter is launched this modulation; The TDCS receiver receives data-signal through the OFDM receiver, and obtains the data that the TDCS transmitter sends by demodulation.
For making purpose of the present invention, technical scheme and advantage clearer, below with reference to the accompanying drawing preferred embodiment that develops simultaneously, the present invention is described in more detail.
Before introducing the present invention program, earlier existing OFDM (OFDM, OrthogonalFrequency Division Multiplexing) technology is done simple introduction.OFDM is with high-speed serial data demultiplexing low-speed parallel data, and respectively different carrier frequency is modulated, and by adding Cyclic Prefix at transmitting terminal, removes Cyclic Prefix with the opposing multidiameter delay at receiving terminal simultaneously.The OFDM transmitter is used for carrying out transmitting invert fast fourier transformation, and with the time domain sequences that obtains after the conversion or be called and launch after the time domain data signal adds Cyclic Prefix, the OFDM receiver is used to estimate radio channel characteristic, Cyclic Prefix in the time domain sequences that receives is removed, and the time domain sequences that will remove Cyclic Prefix is carried out discrete Fourier transform (DFT), sequence after the conversion is carried out channel equalization, thus opposing intersymbol interference and frequency selective fading.The OFDM transmitter can be realized the multicarrier parallel transmission easily, but along with increasing of carrier number, the peak-to-average ratio value that it transmits can increase, thereby the linearity to power amplifier is had higher requirement, cause equipment cost to increase, if can select the lower sequence of peak-to-average ratio value to launch, then can reduce the influence of this point to system cost.
Fig. 3 is the TDCS transmitter composition frame chart that the present invention is based on OFDM, comprises basic sequence generation unit, modulating unit and OFDM transmitter.To being described below of each unit:
The basic sequence generation unit is used to generate basic sequence, and the basic sequence that generates is exported to modulating unit, and the basic sequence generation unit comprises spectrum estimation module, idle frequency spectrum mark module, random phase generation module and memory module.
Wherein, the spectrum estimation module is used for determining glitch-free spectral regions.The method of determining can be periodogram well known in the art, autoregression figure or based on the technology of small echo etc.;
Which frequency free time the idle frequency spectrum mark module is used for determining in the glitch-free spectral regions communication channel, and which frequency is occupied.The method of determining is normally according to the average power signal in the channel spectrum scope, preestablish a spectrum amplitude threshold value, the spectrum estimation value that obtains by spectrum estimation and the comparison of this spectrum amplitude threshold value, to be set at 0 occupied above the frequency of this spectrum amplitude threshold value to represent, the frequency that does not surpass this spectrum amplitude threshold value is set at non-0 value representing the free time, thus generation spectrum amplitude sequence A
k, wherein, k=0,1 ..., N-1, wherein N is the frequency points in the channel spectrum scope;
The random phase generation module is used to generate a random phase sequence e
J θ (k)Wherein, k=0,1 ... N-1.Random phase sequence e
J θ (k)With the spectrum amplitude sequence A
kCorresponding element obtains basic sequence A after multiplier multiplies each other
ke
J θ (k), wherein, k=0,1 ... N-1;
Memory module is used to store the basic sequence A of generation
ke
J θ (k)Also can not need this memory module, so, every generation-inferior basic sequence promptly sends to modulating unit, carries out primary modulation to sent data.
Modulating unit is used to receive the basic sequence from the basic sequence generation unit, utilizes this basic sequence to modulate to sent data-signal, and modulating unit can be made up of data map module and multiplier:
The data map module is used to carry out the data map operation, is about to data S to be sent
iBe mapped as the data of frequency domain
Wherein, k=0,1 ... N-1 is through the outgoing data after the mapping
With basic sequence A
ke
J θ (k)Multiply each other through multiplier and to realize CCSK modulation, the data-signal A that modulation obtains
ke
J θ (k) 
Input to the OFDM transmitter.
The OFDM transmitter is used for the data-signal A after the modulation that receives
ke
J θ (k) 
Carry out inverse discrete Fourier transformer inverse-discrete, obtain the time domain data signal
Wherein, n=0,1 ... N-1; Launch after then s (t) being added Cyclic Prefix.
Correspondingly, Fig. 4 is the TDCS receiver composition frame chart that the present invention is based on OFDM, comprises OFDM receiver, basic sequence generation unit and demodulating unit.To being described below of each unit:
The OFDM receiver, the data-signal s (t) that is used to receive the emission of TDCS transmitter arrives the signal of TDCS receiver behind wireless channel, in the TDCS receiver, this signal is called data-signal r (t), after the data-signal r (t) that receives handles through the OFDM receiver, remove Cyclic Prefix and be converted to frequency domain data signal R (k) and export to demodulating unit from time domain data signal r (t)
Wherein, k=0,1 ... N-1, n
O1Additive white Gaussian noise in [k] expression frequency domain.
The basic sequence generation unit is used to generate basic sequence, and the basic sequence that generates is exported to demodulating unit, and the basic sequence generation unit comprises idle frequency spectrum mark module, random phase generation module.
Wherein, spectrum estimation module, idle frequency spectrum mark module and random phase generation module adopt respectively with TDCS transmitter of the present invention in identical method, generate the spectrum amplitude sequence A '
kWith random phase sequence e
J θ ' (k), the random phase sequence e of gained
J θ ' (k)With the spectrum amplitude sequence A '
kCorresponding element obtains basic sequence A ' after multiplier multiplies each other
ke
J θ ' (k), wherein, k=0,1 ... N-1.
Demodulating unit, be used to receive basic sequence from the basic sequence generation unit, utilize this basic sequence that the data-signal from the OFDM receiver is carried out demodulation, demodulating unit can be by district conjugate module, invert fast fourier transformation module, get real part module, maximum subscript search module and multiplier and form:
Get conjugate module, be used for basic sequence A '
ke
J θ ' (k)Get conjugation, generate conjugate A '
ke
-j θ ' (k), wherein, k=0,1 ... N-1, the conjugate A ' of generation
ke
-j θ ' (k)Multiply each other with frequency domain data signal R (k) corresponding element, and obtain receiving vector R (k) after removing random phase from the OFDM receiver;
Need to prove, the processing of OFDM receiver, do not have clear and definite sequencing with idle frequency spectrum mark module, random phase generation module and the processing of getting conjugate module, both can be walk abreast or idle frequency spectrum mark module, random phase generation module and the processing of getting conjugate module before the processing of OFDM receiver;
The invert fast fourier transformation module is used for obtaining time domain reception vector to receiving vector R (k) execution inverse discrete Fourier transformer inverse-discrete
(l);
Get the real part module, be used for time domain is received vector
(l) get real part, obtain real part and receive vector
Here also can receive vector to time domain
(l) delivery, comprise mould and mould square, delivery belongs to technology as well known to those skilled in the art, no longer describes in detail here, just emphasizes to obtain the information of reception by delivery.
Maximum subscript search module is used for receiving vector from real part
Starting point begin, equally spaced extract order of modulation M element setting in advance as the judgement sequence, in adjudicating sequence, search the pairing subscript of amplitude maximum element, thereby obtain receiving the estimated value of data-signal
Realization from the invention described above TDCS transceiver, TDCS transmitter of the present invention is based on the OFDM transmitter, by using ripe OFDM transmitter techniques, help and existing OFDM technical compatibility, such as the inverse discrete Fourier transformer inverse-discrete that can directly utilize in the OFDM transmitter, and after conversion, add Cyclic Prefix etc.; Carrying out message transmission with direct use OFDM transmitter and compare, is at basic sequence owing to transmit
Last employing CCSK modulation, and basic sequence
Generally all be configured to the lower sequence of peak-to-average ratio, therefore, the data-signal that the present invention is based on the TDCS transmitter transmission of OFDM has lower peak-to-average ratio value;
Adopt the OFDM receiver and, avoided complicated correlator, thereby made that the TDCS transceiver implementation that the present invention is based on OFDM is simple by the achieve a butt joint demodulation of the data-signal received of demodulating unit;
In fading channel and multipath propagation environment, because TDCS receiver of the present invention uses the OFDM technology, channel estimating realizes easily, thereby avoided complicated Rake receiver, makes that realizing becomes more cries simply; In the TDCS receiver,, promptly only search for order of modulation M the point that sets in advance, rather than global search has improved the performance of search speed and communication system by dwindling solid part signal Vector search scope.
The above is preferred embodiment of the present invention only, is not to be used to limit protection scope of the present invention, all any modifications of being made within the spirit and principles in the present invention, is equal to replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (8)
1. a transform domain communication system TDCS transceiver is characterized in that, comprises TDCS transmitter and TDCS receiver,
The TDCS transmitter comprises: basic sequence generation unit, modulating unit and orthogonal frequency division multiplex OFDM transmitter,
Wherein, the basic sequence generation unit is used to generate basic sequence, comprising: spectrum estimation module, idle frequency spectrum mark module and random phase generation module,
Modulating unit, the data-signal to be sent that is used for receiving is mapped as the frequency domain data signal, receives the basic sequence from the basic sequence generation unit, and this basic sequence and frequency domain data signal be multiply by mutually realize cyclic shift keying CCSK modulation,
The OFDM transmitter is used for frequency domain data signal after the multiplying each other of automodulation unit in the future and carries out inverse discrete Fourier transformer inverse-discrete and obtain the time domain data signal, launches after adding Cyclic Prefix;
The TDCS receiver comprises: OFDM receiver, basic sequence generation unit and demodulating unit,
Wherein, the OFDM receiver, the time domain data signal that is used for the interpolation Cyclic Prefix that will receive removes Cyclic Prefix, and exports to demodulating unit after being converted to the frequency domain data signal,
The basic sequence generation unit is used to generate basic sequence, and the basic sequence that generates is exported to demodulating unit,
Demodulating unit is used for that the basic sequence that receives is got conjugation and obtains conjugate, calculates the conjugate of acquisition and the product of the frequency domain data signal that described OFDM receiver is converted to, and obtains receiving vector after removing random phase; Described reception vector is carried out inverse discrete Fourier transformer inverse-discrete obtain time domain reception vector; Described time domain is received vector get real part, obtain real part and receive vector; Receive the vector from described real part and to obtain the judgement sequence, in the judgement sequence, search the pairing subscript of amplitude maximum element, obtain the estimated value of the pairing described data-signal to be sent of this subscript.
2. TDCS transceiver according to claim 1 is characterized in that, the basic sequence generation unit of described TDCS receiver comprises: spectrum estimation module, idle frequency spectrum mark module and random phase generation module.
3. TDCS transceiver according to claim 1 and 2 is characterized in that described modulating unit comprises data map module and multiplier;
Described data map module receives data-signal to be sent, from the basic sequence of the basic sequence generation unit of described TDCS transmitter; The data-signal to be sent that receives is mapped as the frequency domain data signal, and after multiplying each other in described multiplier with basic sequence, exports to the OFDM transmitter from the basic sequence generation unit of described TDCS transmitter.
4. TDCS transceiver according to claim 1 and 2 is characterized in that, described demodulating unit comprises: get conjugate module, invert fast fourier transformation module, get real part module, maximum subscript search module and multiplier;
Get conjugate module, reception is from the basic sequence of the basic sequence generation unit of TDCS receiver, and this basic sequence got conjugation, get basic sequence after the conjugation through multiplier and frequency domain data signal multiplication, and remove and export to the invert fast fourier transformation module after obtaining receiving vector after the random phase from described OFDM receiver;
The invert fast fourier transformation module, be used for will receive the reception vector carry out inverse discrete Fourier transformer inverse-discrete and obtain time domain and receive vector, and send to and get the real part module;
Get the real part module, be used for that the time domain that receives is received vector and get real part, obtain real part and receive vector, and send to maximum subscript search module;
Maximum subscript search module is used for receiving vector from the real part that receives and extracts the judgement sequence, searches the pairing subscript of amplitude maximum element in the judgement sequence, obtains the estimated value of the data-signal to be sent of this subscript correspondence.
5. TDCS transceiver according to claim 3 is characterized in that, the basic sequence generation unit of described TDCS transmitter also comprises: memory module is used to store the basic sequence that the basic sequence generation unit of described TDCS transmitter generates.
6. the implementation method of a transform domain communication system TDCS transceiver, it is characterized in that, this method comprises: transmitting terminal generates basic sequence, to obtain the frequency domain data signal after the data-signal mapping to be sent, the basic sequence of described frequency domain data signal and the generation of described transmitting terminal be multiply by realization cyclic shift keying CCSK modulation mutually, frequency domain data signal after the orthogonal frequency division multiplex OFDM transmitter will multiply each other is carried out inverse discrete Fourier transformer inverse-discrete and is obtained the time domain data signal, and to launching behind the time domain data signal interpolation Cyclic Prefix that obtains, the method that described transmitting terminal generates basic sequence is:
A1. determine noiseless spectral regions, and in this glitch-free spectral regions, generate the spectrum amplitude sequence;
A2. generate the random phase sequence, and obtain basic sequence according to the random phase sequence and the spectrum amplitude sequence that generate;
Receiving terminal receives the time domain data signal that adds Cyclic Prefix through the OFDM receiver, removes Cyclic Prefix and is converted to the frequency domain data signal; Receiving terminal generates basic sequence; The basic sequence that the receiving terminal that obtains is generated is got conjugation and is obtained conjugate, and calculates the product of the frequency domain data signal that the conjugate that obtains and described receiving terminal be converted to, and obtains receiving vector after removing random phase; Described reception vector is carried out inverse discrete Fourier transformer inverse-discrete obtain time domain reception vector; Described time domain is received vector get real part, obtain real part and receive vector; Receive the vector from described real part and to obtain the judgement sequence, in the judgement sequence, search the pairing subscript of amplitude maximum element, obtain the estimated value of the pairing described data-signal to be sent of this subscript.
7. method according to claim 6 is characterized in that, in the steps A 2, the described method of obtaining basic sequence is: the product that calculates described random phase sequence and spectrum amplitude sequence corresponding element.
8. method according to claim 6 is characterized in that, the method that described receiving terminal generates basic sequence is:
B1. generate the random phase sequence, and obtain basic sequence according to the random phase sequence and the spectrum amplitude sequence that generate.
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| CN102647390A (en) * | 2012-03-21 | 2012-08-22 | 电子科技大学 | Transform domain communication system and realization method thereof |
| CN102647390B (en) * | 2012-03-21 | 2014-10-15 | 电子科技大学 | Transform domain communication system and realization method thereof |
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| CN1984108A (en) | 2007-06-20 |
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