CN101702704A - Method, device and system for multi-carrier spread spectrum transmission and reception in time domain synchronization - Google Patents

Abstract

The invention discloses a receiving and transmitting method of multi-carrier spectrum spreading with synchronous time domain, a device and a system thereof. The transmitting method comprises the following steps: S1, carrying out spectrum spreading on the original data of each user with spreading codes and then overlying; S2, carrying out serial and parallel transformation on the overlaid spectrum spreading signals to obtain a plurality of parallel signal flow; S3, carrying out Fourier inverse transformation on the signals to generate an OFDM data block; S4, inserting a known sequence in front of the OFDM data block as the guard interval of the OFDM data block; and S5, carrying out serial and parallel transformation on the data obtained in S4 to obtain a multi-carrier spectrum spreading baseband signal with synchronous time domain, and transmitting the signal. The inventive technical scheme introduces CDMA technology into TDS-OFDM technology, thus TDS-OFDM technology has outstanding multi-address access capacity; the cyclic prefix in the MC-CDMA system is replaced by a known training sequence as the guard interval of the OFDM data block, thus the frequency spectrum efficiency of the system is improved.

Description

The multi-carrier spread spectrum receiving/transmission method of Domain Synchronous, Apparatus and system

Technical field

The present invention relates to communication technical field, particularly a kind of multi-carrier spread spectrum receiving/transmission method, Apparatus and system of Domain Synchronous.

Background technology

With TDMA (Time Division Multiple Access, time division multiple access), FDMA (Frequency Division Multiple Access, frequency division multiple access) technology is compared, CDMA (Code Division Multiple Access, code division multiple access) technology has unarguable advantage at aspects such as power system capacity, anti-interference, network quality and confidentiality.But, CDMA is that multiple access disturbs and the multipath interference limiting system, when the signal of transmission higher rate, the code-element period of cdma system shortens greatly, thereby when (broadband) transfer of data at a high speed, must be subjected to the influence of intersymbol interference, when especially transmitting in the more serious wireless channel of multipath fading, intersymbol interference is even more serious.Because the restriction of multipath fading and existing frequency bandwidth, the message transmission rate of cdma system can only reach 2Mbps, and data rate is lower, the growth requirement of not competent high-speed multimedia data communication.

And OFDM (Orthogonal Frequency Division Multiplexing, OFDM) technology has excellent properties such as anti-channel fading and anti-multipath interference just, be specially adapted to the wireless high-speed data transmission, its message transmission rate can be up to arriving 100Mbps, far above cdma system.This is that at transmitting terminal, the two-forty information data is divided into the several rate data streams because in ofdm system, modulates with same group of respective numbers and mutually orthogonal carrier wave then, and the signal after all modulation superposes and sends; At receiving terminal, the quadrature carrier that adopts same quantity carries out coherent reception to sending signal, obtain the low rate information data after, be converted to original two-forty information by parallel/serial again.By the basic principle of OFDM as can be known, ofdm system be the information dispersion that will transmit to many subcarriers, each sub-carrier signal speed is descended greatly, thereby can resist the multipath effect in the two-forty modulating system effectively.Up to the present, the OFDM technology has obtained in IEEE 802.11a/g, 802.11n (WLAN/Wi-Fi), WiMAX, UWB, DVB, B3G (LTE)/fields such as 4G extensively and successful application.

Therefore, many researchers begin to consider OFDM and CDMA technology are merged, and promptly inquire into OFDM and CDMA hybrid technology, so that made full use of OFDM and two technology of CDMA advantage separately.At present very extensive at the research direction of two technological incorporation, the multicarrier CDMA scheme of main flow has following three kinds: MC-CDMA (Multi-carrierCDMA), MC-DS-CDMA (Multi-carrier Direct Spreading CDMA), MT-CDMA (Multi-tone CDMA).Existing document analysis shows, remarkable advantage such as that MC-CDMA has is simple in structure, ability of anti-multipath is strong, anti-narrow band interference ability is strong, the availability of frequency spectrum is high, data rate is high, the multiple access access capability is superior, and its combination property is better than all the other two kinds of schemes, has therefore obtained extensive studies and application.

In the MC-CDMA technology of research at present, the same with ofdm system, in order to eliminate the influence of ISI (Inter-Symbol Interference, intersymbol interference), need to add Cyclic Prefix at interval as protection.In addition, carry out functions such as synchronous and channel estimating realizes for auxiliary receiver, also need between the useful data of frequency domain, insert the pilot tone that accounts for total number ofsub-carriers 5%～15%, and this can reduce the spectrum efficiency of MC-CDMA system undoubtedly, in frequency spectrum resource precious today, this obviously runs counter to the demand of development communication technologies.

Summary of the invention

The present invention is directed to the deficiencies in the prior art, in order to improve the spectrum efficiency of traditional MC-CDMA system, CDMA and TDS-OFDM (Time Domain SynchronousOrthogonal Frequency-Division-Multiplex has been proposed, time-domain synchronization OFDM) a kind of new multi-carrier spread spectrum method of sending and receiving that combines of these two kinds of technology, this method is the multi-carrier spread spectrum technology that a kind of TDS-OFDM of making technology possesses outstanding multiple access access capability, simultaneously, this system is different from traditional MC-CDMA technology again after the advantage of having used for reference the TDS-OFDM technology, make the more traditional MC-CDMA technology of its spectrum efficiency improve 5%～15%.

For achieving the above object, technical scheme of the present invention provides a kind of multi-carrier spread spectrum sending method of Domain Synchronous, said method comprising the steps of:

S1 carries out each user's initial data to superpose behind the spread spectrum with spreading code;

S2 carries out serial to parallel conversion with the spread-spectrum signal after the stack, obtains a plurality of parallel signal flows;

S3 will generate the OFDM data block behind the described signal flow process inverse fourier transform;

S4 inserts training sequence as protection at interval before described OFDM data block;

S5, the data that step S4 is obtained send this signal through obtaining the multi-carrier spread spectrum baseband signal of Domain Synchronous behind the parallel serial conversion.

Wherein, described spreading code is quadrature or quasi-orthogonal sequence.

Described training sequence is a known sequences, and preferably, this sequence is selected from a kind of in PN sequence, Gold sequence, Walsh sequence, Kasami sequence, LA sequence, the ZCZ sequence.

Described training sequence is a known sequences, and preferably, this sequence is selected from a kind of through the sequence of inverse Fourier transform after the time domain in PN sequence, Gold sequence, Walsh sequence, Kasami sequence, LA sequence, the ZCZ sequence.

The present invention also provides a kind of multi-carrier spread spectrum dispensing device of Domain Synchronous, and described device comprises:

Spread spectrum module is used for each user's initial data is carried out superposeing behind the spread spectrum with spreading code;

The serial to parallel conversion module is used for the spread-spectrum signal after the stack is carried out serial to parallel conversion, obtains a plurality of parallel signal flows;

The inverse fourier transform module is used for described signal flow through generating the OFDM data block behind the inverse fourier transform;

Insert the protection interval module, be used for before described OFDM data block, inserting training sequence at interval as protection;

The parallel serial conversion module, the data that are used for described insertion protection interval module is obtained send this signal through obtaining the multi-carrier spread spectrum baseband signal of Domain Synchronous behind the parallel serial conversion.

The present invention also provides a kind of multi-carrier spread spectrum method of reseptance of Domain Synchronous, said method comprising the steps of:

S1 carries out serial to parallel conversion with the multi-carrier spread spectrum baseband signal of the Domain Synchronous that receives;

S2 is to obtaining the OFDM data block behind the data separating training sequence that obtains behind the serial to parallel conversion;

S3 carries out Fourier transform with described OFDM data block;

S4 carries out the data flow through obtaining behind the Fourier transform to obtain serial data behind the parallel serial conversion;

S5 carries out despreading with described serial data with spreading code, recovers each user's initial data.

Wherein, described spreading code is quadrature or quasi-orthogonal sequence.

The present invention also provides a kind of multi-carrier spread spectrum receiving system of Domain Synchronous, and described device comprises:

The serial to parallel conversion module, the multi-carrier spread spectrum baseband signal that is used for the Domain Synchronous that will receive is carried out serial to parallel conversion;

Separate the protection interval module, be used for obtaining the OFDM data block behind the data separating training sequence that obtains behind the serial to parallel conversion;

Fourier transform module is used for described OFDM data block is carried out Fourier transform;

The parallel serial conversion module is used for the data flow through obtaining behind the Fourier transform is carried out obtaining serial data behind the parallel serial conversion;

The despreading module is used for described serial data is carried out despreading with spreading code, recovers each user's initial data.

The present invention also provides a kind of multi-carrier spread spectrum receiving/transmission method of Domain Synchronous, said method comprising the steps of:

The signal forwarding step utilizes the multi-carrier spread spectrum sending method of above-mentioned Domain Synchronous to send signal;

The signal receiving step utilizes the multi-carrier spread spectrum method of reseptance received signal of above-mentioned Domain Synchronous.

The present invention also provides a kind of multi-carrier spread spectrum receive-transmit system (hereinafter referred to as the TDS-MC-CDMA system) of Domain Synchronous, and described system comprises the multi-carrier spread spectrum generating means of above-mentioned Domain Synchronous and the multi-carrier spread spectrum receiving system of above-mentioned Domain Synchronous.

Technique scheme has following advantage: by introducing CDMA technology in the TDS-OFDM technology, thereby make the TDS-OFDM technology possess more superior multiple access access capability; With known training sequence replaced in the MC-CDMA system Cyclic Prefix as the protection of IDFT data block at interval, thereby make the spectrum efficiency of system be improved.

Description of drawings

Fig. 1 is the theory diagram of the TDS-MC-CDMA system of the embodiment of the invention;

Fig. 2 is the comparison diagram of signal frame structure in the TDS-MC-CDMA system of the MC-CDMA system of prior art and the embodiment of the invention;

Fig. 3 is the BER performance comparison figure of the TDS-OFDM system of the TDS-MC-CDMA system of the embodiment of the invention under the awgn channel and prior art;

Fig. 4 is the TDS-MC-CDMA of the embodiment of the invention and BER performance comparison and the anti-multipath property comparison figure of DS-CDMA system under awgn channel of prior art;

Fig. 5 is the TDS-MC-CDMA of the embodiment of the invention and the BER performance comparison figure of MC-CDMA system under awgn channel and multipath channel of prior art;

Fig. 6 is the BER performance chart of TDS-MC-CDMA system under various typical multipath channel models of the embodiment of the invention;

Fig. 7 is the simulation result of the TDS-MC-CDMA system of the embodiment of the invention at the resisting multi-user jamming performance.

Embodiment

Below in conjunction with drawings and Examples, the specific embodiment of the present invention is described in further detail.Following examples are used to illustrate the present invention, but are not used for limiting the scope of the invention.

Fig. 1 is the theory diagram according to the TDS-MC-CDMA system of the embodiment of the invention.

As shown in Figure 1, transmitting terminal in the TDS-MC-CDMA system, at first carry out being superimposed behind the spread spectrum from the data of different user, pass through the time domain data that obtains being referred to as the IDFT data block after serial to parallel conversion, the inverse Fourier transform (IDFT/IFFT) then through different spreading codes.Before the IDFT data block, insert known sequences as training sequence, thereby constitute the TDS-MC-CDMA signal frame, behind the parallel serial conversion signal is launched then.Above-mentioned process of transmitting is below described for example.

Suppose that the number of users in the TDS-MC-CDMA system is K, the data symbol of user k correspondence is d^(k), its character rate is 1/T_dAt first, data symbol is by the specific spreading code of user

Carry out spread spectrum, spreading code c before the serial to parallel conversion^(k)Spreading rate be

$\frac{1}{T_c}=\frac{N}{T_d},---\left(1\right)$

Spreading rate is N a times of data symbol rate.The sequence free list that obtains behind the spread spectrum is shown vector

$s^{\left(k\right)}=d^{\left(k\right)}\·c^{\left(k\right)}={[S_0^{\left(k\right)},S_1^{\left(k\right)},...,S_{N-1}^{\left(k\right)}]}^T.---\left(2\right)$

K user's data s^(k)Be superimposed, can be expressed as

$s=\underset{k=0}{\overset{K-1}{\mathrm{\&Sigma;}}}{s}^{\left(k\right)}={[{\mathrm{<figure-callout\; label="S"\; filenames="H2009102377213E0000021.png,H2009102377213E0000031.png"\; state="\{\{state\}\}">S</figure-callout>}}_0,{\mathrm{<figure-callout\; label="S"\; filenames="H2009102377213E0000021.png,H2009102377213E0000041.png"\; state="\{\{state\}\}">S</figure-callout>}}_1,...,S_{N-1}]}^T.---\left(3\right)$

Following formula can be expressed in matrix as:

s＝C·d，????????????????????????????????(4)

Wherein

d＝[d⁽⁰⁾，d⁽¹⁾，...，d^(K-1)]^T????????????(5)

Be the vector representation of K user's transmission symbol, C then is the spreading code matrix, is expressed as:

C＝[c⁽⁰⁾，c⁽¹⁾，...，c^(K-1)].???????????(6)

After finishing above-mentioned spread spectrum process, at first serial data is at a high speed become the parallel data of low speed through serial to parallel conversion through the sequence s of spread spectrum, pass through IFFT (Inverse FastFourier Transform then, invert fast fourier transformation) (suppose that total number of sub-carriers equals frequency expansion sequence length), thereby obtain the sequence after the OFDM modulation:

x＝w^H·s＝[x⁽⁰⁾，x⁽¹⁾，...，x^(N-1)]^T???????????(7)

Wherein []^HThe conjugate transpose of representing matrix, w are the IFFT transformation matrix of N * N, (m, n) the individual element w of w_{M, n}Be expressed as

$w_{m,n}=\frac{1}{\sqrt{N}}{e}^{-\mathrm{<figure-callout\; label="j"\; filenames="H2009102377213E0000021.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{2\mathrm{\&pi;}}{N}(m-1)(n-1)},1\&le;m,n\&le;N---\left(8\right)$

After obtaining time domain OFDM symbol x, be N with length_gKnown training sequence

Be filled in conduct protection interval between the OFDM symbol, thereby constitute TDS-MC-CDMA signal frame as shown in Figure 2.Length is N_s=N+N_g, comprise time domain protection TDS-MC-CDMA signal frame t at interval and can be expressed as:

$t={\left[p^T{x}^T\right]}^T=W_{\mathrm{ZP}}^H\&CenterDot;x+p_{\mathrm{ZP}}.---\left(9\right)$

Wherein$W_{\mathrm{ZP}}^H={\left[0_{N,N_g}{I}_N^T\right]}^T\&CenterDot;W^H,$p_ZP＝[p^T0_1，N]^T。

What the receiving terminal of TDS-MC-CDMA was carried out be and transmitting terminal inverse process one to one.Promptly, at first pass through serial to parallel conversion through the channel and the baseband signal behind the noise that superposeed, separate IDFT data block and known training sequence then, obtain frequency domain data after the IDFT data block that obtains done Fourier transform (DFT/FFT), use the spreading code despreading corresponding to go out each user's signal then with the user.

The frequency domain data r that obtains behind the FFT (Fast Fourier Transform, fast fourier transform) can be expressed as:

r＝Hs+n＝[R₀，R₁，...，R_N-1]^T，?????????(10)

Wherein H is the channel matrix of N * N, and n is that length is the noise vector of N.Receiver carries out soft-decision or hard decision to r, thus the frequency domain symbol vectors after obtaining adjudicating

For Multiuser Detection, following formula can be rewritten as

r＝As+n＝[R₀，R₁，...，R_N-1]^T，?????????(11)

Wherein sytem matrix A is defined as:

A＝HC???????????????????????????????????(12)

If receiver can carry out correct judgement to r, promptly

$\hat{r}=s.---\left(13\right)$

Utilize the orthogonality of spreading code between different user:

$c^{\left(j\right)}\&CenterDot;c^{\left(k\right)}=\left\{\begin{array}{cc}N& j=k\\ 0& j\&NotEqual;k\end{array}\right.---\left(14\right)$

With the spreading code c corresponding with each user^(k)Respectively with judgement after the symbolic vector that obtains

Multiply each other, can finish the despreading process in the TDS-MC-CDMA system, thereby recover each user's data:

$\hat{r}\&CenterDot;c^{\left(k\right)}=(\underset{k=0}{\overset{K-1}{\mathrm{\&Sigma;}}}{d}^{\left(k\right)}\&CenterDot;c^{\left(k\right)})\&CenterDot;c^{\left(k\right)}=N\&CenterDot;d^{\left(k\right)}$1≤k≤K.

(15)

Spreading code in the multi-carrier spread spectrum receiving/transmission method of the Domain Synchronous of the embodiment of the invention can be any quadrature or quasi-orthogonal sequence, as m sequence, Gold sequence, Walsh sequence or other any quadratures or quasi-orthogonal sequence.And spreading factor (being the length of spreading code) can come flexible configuration according to the demand of system design and the characteristics of spreading code itself, and selecting the Walsh sequence for use with spreading code is example, and spreading code length can be 1,2,4,8,16.Total number of sub-carriers in the frame structure of this method can be come flexible configuration according to the demand of system design, can be 64,256,1024,2048,8196.Training sequence can be any known sequences, as m sequence, Gold sequence, Walsh sequence, Kasami sequence, LA sequence, ZCZ sequence etc.For known known training sequence in the multi-carrier spread spectrum method of sending and receiving of Domain Synchronous, the special characteristic that this sequence possessed, can be on time domain, also can be on frequency domain, particularly, selecting length for use with training sequence is that 127 m sequence is an example, for example, the special characteristic of training sequence on time domain, promptly training sequence itself be exactly length be 127 m sequence; The special characteristic of training sequence can be on frequency domain, and promptly training sequence itself is not that length is 127 m sequence, but length is that 127 m sequence is through the resulting sequence after the inverse Fourier transform.

As can be seen from the above embodiments, with maximum different being of TDS-OFDM system, having introduced CDMA technology in the TDS-MC-CDMA system that the present invention proposes, thereby made this technology of TDS-OFDM possess superior multiple access access capability.In addition, only limit to the PN sequence with time-domain training sequence in the TDS-OFDM system or expansion PN sequence is different, the known training sequence in the TDS-MC-CDMA system that the present invention proposes can be any known sequences.In addition, to only limit to time domain different with training sequence in the TDS-OFDM system, known training sequence itself in the TDS-MC-CDMA system that the present invention proposes can not be the sequence that has possessed some certain features on time domain, but on frequency domain, possess the sequence of some certain features, be fourier transformed into sequence after the time domain as processes such as PN sequences.Maximum different being with traditional MC-CDMA system; the TDS-MC-CDMA system that the present invention proposes uses for reference and has expanded the notion of Domain Synchronous in the TDS-OFDM system; replaced the protection interval of the Cyclic Prefix among the MC-CDMA with known training sequence, thereby made the spectrum efficiency of this multi-carrier spread-spectrum system improve about 5%～15% as the IDFT data block.Fig. 2 has provided the contrast of signal frame structure in this two different multi-carrier spread-spectrum system of MC-CDMA and TDS-MC-CDMA, we are as can be seen from figure, signal frame in the MC-CDMA system is made of IDFT data block and Cyclic Prefix thereof, and the signal frame in the TDS-MC-CDMA system then is made of IDFT data block and known training sequence.

Based on above-mentioned specific embodiment, we have carried out Computer Simulation to the main performance of the synchronous multi-carrier spread spectrum communication system (TDS-MC-CDMA) of major parameter non-coded time domain as shown in table 1.The channel that emulation is adopted is four kinds of multipath channel models that AWGN (Additive White GaussionNoise, additive white Gaussian noise) channel and ITU (International TelecommunicationUnion, International Telecommunication Association) recommend.Table 1 is the major parameter of TDS-MC-CDMA system emulation; Table 2 is the ITU multipath channel models.

Table 1

Spreading code	The Walsh sequence
		Spreading factor	??1、2、4、8、16
Subcarrier is total	??1024
		Between subcarrier	??5kHz
Character rate	??5MHz
		Training sequence	The Walsh sequence
Training sequence	??128
		Modulation system	??BPSK、QPSK、16QAM、
Channel is compiled and is separated	Do not have

Table 2

Fig. 3 has provided the BER performance comparison of TDS-MC-CDMA system and TDS-OFDM system under the awgn channel, and in different spreading factors (SF) the BER performance of TDS-MC-CDMA system down.Modulation system is BPSK.As can be seen, under different spreading factors, the TDS-MC-CDMA system will obtain spreading gain SF from simulation result, and spreading factor is big more, and then the BER performance of system is good more; (be equivalent to not spread spectrum) when SF=1, TDS-MC-CDMA deteriorates to general TDS-OFDM system, and this moment, the BER of the two was in full accord.Simulation result also shows, when the TDS-MC-CDMA system is buried in the noise at subscriber signal fully, and the extraction user data that system still can be correct.Getting 2 with spreading factor SF is example, even when the channel signal to noise ratio is zero, the TDS-MC-CDMA system receiving terminal error rate still can reach 0.002, if technology such as the chnnel coding of adding or forward error corrections, system still just can satisfy the requirement that real system is used in this case.And the TDS-OFDM system is powerless already.

Fig. 4 has provided TDS-MC-CDMA and DS-CDMA system BER performance comparison and the anti-multipath property comparison under awgn channel.The spreading factor of the two is 16, and modulation system is BPSK.As can be seen, under awgn channel, the TDS-MC-CDMA system promotes about 3dB than DS-CDMA systematic function from simulation result.Under ITU indoor multipath channel model A, the BER performance of TDS-MC-CDMA and DS-CDMA system all worsens, but MC-CDMA has the stronger ability to anti-multipath than DS-CDMA.In Fig. 4, when BER=0.001, the Normalized Signal/Noise Ratio thresholding of DS-CDMA system is brought up to 8.5dB from-2.5dB, be that signal to noise ratio need improve 11dB, but in the TDS-MC-CDMA system, bring up to-1.7dB from-5.3dB, promptly signal to noise ratio need improve 3.6dB, much smaller than the required 11dB of DS-CDMA system.Because the TDS-MC-CDMA multicarrier can come flexible allocation resource (as transmitting power, modulation system etc.) according to the characteristic of different sub carrier upper signal channel, and can carry out frequency interlacing very easily, therefore, after having adopted bit loading and frequency-domain-interleaving technology, the ability of the how anti-frequency-selective channel of MC-CDMA will strengthen again greatly.

Fig. 5 has provided TDS-MC-CDMA and the MC-CDMA system BER performance comparison under awgn channel and multipath channel.As can be seen, TDS-MC-CDMA is all consistent with MC-CDMA with BER performance under the multipath channel at AWGN from simulation result.But as noted before; because TDS-MC-CDMA has adopted known training sequence to replace the Cyclic Prefix among the MC-CDMA as protection at interval; and known training sequence can be carried out synchronously and channel estimating as auxiliary receiver; thereby need not extra pilot tone, thereby make the efficiency of transmission of TDS-MC-CDMA system improve about 5%～15%.

Fig. 6 has provided the BER performance curve of TDS-MC-CDMA system under various typical multipath channel models.Under awgn channel, the BER performance of system is best; Along with the enhancing of multipath, the BER mis-behave, in the vehicle-mounted multipath channel models B of the most tangible ITU of multipath effect, BER worsens at most.

Indoor represents indoor environment in Fig. 4～6; Vehicular represents vehicle environment.Usernumber represents number of users among Fig. 7.

Fig. 7 has provided the simulation result of TDS-MC-CDMA system at the resisting multi-user jamming performance.System adopt spreading factor be 16 Walsh sequence as spreading code, modulation system is BPSK.Because the Walsh sequence between the different user is completely orthogonal, so when number of users is less than or equal to 16, but the equal despreading of TDS-MC-CDMA system goes out used user's signal.The simulation result of Fig. 7 shows that also when having the multi-user (16 users), because the complete quadrature of spreading code between each user, the BER of its system and single user are in full accord, therefore can avoid multi-user interference fully.

The present invention is the organically blending of core technology TDS-OFDM (Time Domain Synchronous-OFDM) of CDMA technology and Chinese terrestrial DTV transmission standard, we are referred to as the multi-carrier spread spectrum receiving/transmission method of Domain Synchronous, i.e. the receiving/transmission method of TDS-MC-CDMA (TimeDomain Synchronous-Multi Carrier-CDMA) system.As can be seen from the above embodiments; in the present invention; we fully use for reference this original technology of TDS-OFDM (referring to the national standard of issuing in August, 2006 " (the frame structure chnnel coding and the modulation of digital television ground broadcast transmission system "; GB 20600-2006), adopt known sequences to be inserted between the OFDM data block at interval as protection as training sequence rather than as the Cyclic Prefix in the traditional MC-CDMA system.The known array that inserts not only can play protection work at interval in order to eliminate ISI; can also be used for auxiliary reception carries out synchronously and channel estimating; therefore in the TDS-MC-CDMA scheme, need not extra pilot tone, thereby make the spectrum efficiency of this multi-carrier spread-spectrum system improve about 5%～15%.On the other hand, TDS-OFDM is mainly used in descending broadcast channel transmission, do not have the multiple access access capability, and the TDS-MC-CDMA scheme that the present invention proposes not only makes this technology of TD-OFDM possess the function that multiple access inserts, and the multiple access access capability of this scheme be much higher than proposed in 2009 based on the multiple access access scheme TDS-OFDMA of TDS-OFDM (with reference to L.Dai, J.Fu, etc, " ANovel Time Domain Synchronous Orthogonal Frequency DivisionMultiple Access Scheme; " in Proc.IEEE Global CommunicationsConference (Globecom ' 09), Hawaii, USA, Nov.2009).

The above only is a preferred implementation of the present invention; should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the technology of the present invention principle; can also make some improvement and modification, these improve and modification also should be considered as protection scope of the present invention.

Claims (9)

1. the multi-carrier spread spectrum sending method of a Domain Synchronous is characterized in that, said method comprising the steps of:

S1 carries out each user's initial data to superpose behind the spread spectrum with spreading code;

S2 carries out serial to parallel conversion with the spread-spectrum signal after the stack, obtains a plurality of parallel signal flows;

S3 will generate the OFDM data block behind the described signal flow process inverse fourier transform;

S4 inserts training sequence as protection at interval before described OFDM data block;

S5, the data that step S4 is obtained send this signal through obtaining the multi-carrier spread spectrum baseband signal of Domain Synchronous behind the parallel serial conversion.

2. the multi-carrier spread spectrum sending method of Domain Synchronous as claimed in claim 1 is characterized in that, described training sequence is a known sequences, and this sequence is a kind of in PN sequence, Gold sequence, Walsh sequence, Kasami sequence, LA sequence, the ZCZ sequence.

3. the multi-carrier spread spectrum sending method of Domain Synchronous as claimed in claim 1, it is characterized in that, described training sequence is a known sequences, and this sequence is a kind of through the sequence of inverse Fourier transform after the time domain in PN sequence, Gold sequence, Walsh sequence, Kasami sequence, LA sequence, the ZCZ sequence.

4. the multi-carrier spread spectrum dispensing device of a Domain Synchronous is characterized in that, described device comprises:

Spread spectrum module is used for each user's initial data is carried out superposeing behind the spread spectrum with spreading code;

The serial to parallel conversion module is used for the spread-spectrum signal after the stack is carried out serial to parallel conversion, obtains a plurality of parallel signal flows;

The inverse fourier transform module is used for described signal flow through generating the OFDM data block behind the inverse fourier transform;

Insert the protection interval module, be used for before described OFDM data block, inserting training sequence at interval as protection;

The parallel serial conversion module, the data that are used for described insertion protection interval module is obtained send this signal through obtaining the multi-carrier spread spectrum baseband signal of Domain Synchronous behind the parallel serial conversion.

5. the multi-carrier spread spectrum method of reseptance of a Domain Synchronous is characterized in that, said method comprising the steps of:

S1 carries out serial to parallel conversion with the multi-carrier spread spectrum baseband signal of the Domain Synchronous that receives;

S2 is to obtaining the OFDM data block behind the data separating training sequence that obtains behind the serial to parallel conversion;

S3 carries out Fourier transform with described OFDM data block;

S4 carries out the data flow through obtaining behind the Fourier transform to obtain serial data behind the parallel serial conversion;

S5 carries out despreading with described serial data with spreading code, recovers each user's initial data.

6. the multi-carrier spread spectrum method of reseptance of Domain Synchronous as claimed in claim 5 is characterized in that, described spreading code is quadrature or quasi-orthogonal sequence.

7. the multi-carrier spread spectrum receiving system of a Domain Synchronous is characterized in that, described device comprises:

The serial to parallel conversion module, the multi-carrier spread spectrum baseband signal that is used for the Domain Synchronous that will receive is carried out serial to parallel conversion;

Separate the protection interval module, be used for obtaining the 0FDM data block behind the data separating training sequence that obtains behind the serial to parallel conversion;

Fourier transform module is used for described OFDM data block is carried out Fourier transform;

The parallel serial conversion module is used for the data flow through obtaining behind the Fourier transform is carried out obtaining serial data behind the parallel serial conversion;

The despreading module is used for described serial data is carried out despreading with spreading code, recovers each user's initial data.

8. the multi-carrier spread spectrum receiving/transmission method of a Domain Synchronous is characterized in that, said method comprising the steps of:

The signal forwarding step utilizes the multi-carrier spread spectrum sending method of the described Domain Synchronous of claim 1 to send signal;

The signal receiving step utilizes the multi-carrier spread spectrum method of reseptance received signal of the described Domain Synchronous of claim 3.

9. the multi-carrier spread spectrum receive-transmit system of a Domain Synchronous is characterized in that, described system comprises the multi-carrier spread spectrum generating means of the described Domain Synchronous of claim 2 and the multi-carrier spread spectrum receiving system of the described Domain Synchronous of claim 4.

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