CN103297101A - Multi-code and multi-carrier CDMA modulation/demodulation method - Google Patents

Abstract

The invention discloses a multi-code and multi-carrier CDMA modulation/demodulation method. The multi-code and multi-carrier CDMA modulation/demodulation method combines the advantages of multi-carrier and multi-spreading-code modulation and space-time coding, improves system capacity, and has better data transmission capacity and a lower error rate, thus, the system performance is improved, the error rate is reduced, and the multi-code and multi-carrier CDMA modulation/demodulation method has wide application value in a multi-data service transmission system.

Description

A kind of CDMA modulation/demodulation methods of many yards multicarriers

Technical field

The present invention relates to the wireless communication industry technical field of data transmission, relate in particular to a kind of CDMA modulation/demodulation methods of many yards multicarriers.

Background technology

CDMA technology is higher because of its power system capacity, realize that soft handover, antijamming capability are strong, advantages such as transmitting power is low, good confidentiality, has been successfully applied in the second generation mobile communication technology.Today of radiotechnics fast development, people also further increase the business demand in the wireless communication system, and volume of transmitted data is increasing, and under this demand background, it is particularly valuable that frequency spectrum resource seems.Therefore, how to improve frequency spectrum resource utilization rate, increase system user capacity, reduce the error rate and become a hot research problem.

The capacity of spectrum CDMA system disturbs (MAI) and multipath to disturb very sensitive to multiple access.Under the finite bandwidth condition, the code-element period of CDMA shortens greatly, when transmitting high-speed data-flow, obviously be subject to the influence of intersymbol interference (ISI) owing to multipath effect, ISI is even more serious when especially transmitting in the more serious wireless channel of multipath fading, this makes cdma system be difficult to take full advantage of frequency spectrum resource, and development is subjected to certain restriction.Along with the fast development of multimedia multi-service transmission technology, the multi-transceiver technology with strong anti-multipath interference and intersymbol interference ability obtains further investigation.

CDMA is the effective means of supporting multi-user communication, adopt multi-carrier transmission can reach the effect of good frequency diversity again, multi-carrier CDMA system can transmit high-speed data-flow in wireless channel, can both obtain bigger benefit at aspects such as spectrum efficiency, frequency diversity, anti-multipath interference.

Space Time Coding is a kind of coded diversity technology for multiple transmit antennas, it can produce spatial domain and relativity of time domain between the transmitting of many transmit antennas and each time cycle, thereby overcome the mimo channel decline and reduce the emission mistake, the diversity gain of raising system and coding gain can be realized the unlimited transmission of spectral efficient.The space-time block code (STBC) that people such as Alamouti propose utilizes the orthogonality of coding, obtains the maximum transmit diversity gain, and can carry out maximum likelihood decoding by linear process at receiving terminal.The basic functional principle of Space Time Coding is as follows: from the inter-area traffic interarea of information source output, arrive after the Space Time Coding device, form the vector of going out from many transmission antennas transmit simultaneously, these modulation symbols are called space-time symbol.

In realizing process of the present invention, though the applicant recognizes prior art CDMA multiple carrier modulating system and has strengthened the ability of anti-multipath effect, simple cdma system has improved frequency spectrum resource utilization rate to a certain extent, but the raising of this utilance is very limited, along with developing rapidly of the continuous multimedia service that increases of data volume, digital communicating field presses for has further raising frequency spectrum resource utilization rate, increase system user capacity, reduce the information transmission system of error rate of system.

Summary of the invention

(1) technical problem that will solve

For solving above-mentioned one or more problems, the invention provides a kind of CDMA modulation/demodulation methods of many yards multicarriers, to increase system user capacity, reduce error rate of system.

(2) technical scheme

A kind of CDMA modulator approach of many yards multicarriers is provided according to an aspect of the present invention.This method comprises: steps A, user data b _kThe process string-and convert the parallel data flow b of M bar to _{K, i}, wherein, 1≤i≤M; Step B is the orthogonal sequence w of N with length _{K, i}The low data flow b parallel to the M bar respectively _{K, i}Carry out band spectrum modulation, wherein, 1≤i≤M; Step C is with the M bar parallel data addition after the band spectrum modulation; Step D copies to L bar orthogonal sub-carriers branch road with the data after the addition; Step e is to data and the PN sequence c of each branch road in the described L bar orthogonal sub-carriers branch road _{K, j}Multiply each other, wherein, 1≤j≤L; Step F is carried out the numeral modulation to the data of each branch road in the described L bar orthogonal sub-carriers branch road; Step G will carry out the data addition of the L bar orthogonal sub-carriers branch road after numeral is modulated, many yards multi-carrier modulation of realization.

According to a further aspect of the invention, a kind of CDMA demodulation method of many yards multicarriers also is provided, has been used for the data that above-mentioned many yards CDMA multiple carrier modulator approaches are modulated are carried out demodulation, having comprised: steps A ', carry out the FFT conversion to the received signal, generate parallel L road signal; Step B ' carries out carrier wave demodulation to each the bar branch road in the described parallel L road signal; Step C ' carries out low-pass filtering to the data of carrying out behind the carrier wave demodulation, peels off carrier wave; Step D ' carries out despreading by the integration differentiation to each the bar branch road in the parallel L road signal, peels off the PN sequence; Step e ', data after the PN sequence are carried out parallel/serial conversion and sampling keeps handling to peeling off; Step F ', the data after the sampling maintenance processing are carried out despreading by the integration differentiation to every branch road, peel off spreading code; Step G carries out serial/parallel conversion to the data of peeling off spreading code, obtains the user data b after the demodulation _k

According to a further aspect of the invention, also provide a kind of CDMA modulator approach of using many yards multicarriers of Space Time Coding.This method comprises: step S1, user data b _kThe process string-and convert the parallel low data flow b of M bar to _{K, i}, wherein, 1≤i≤M; Step S2, each the bar branch road b in the low data flow that the M bar walks abreast _{K, i}Data carry out space-time block code respectively, output M bar branch road; Step S4 delivers to the q strip tributary signal of p Space Time Coding device output q follow-up subsequent step p bar input branch road respectively, wherein, p=1,2 ..., M; Q=1,2 ..., M; Step S5, parallel carries out many yards multi-carrier modulation to M bar branch road; Step S6 carries out parallel/serial conversion to the data of L bar branch road respectively, carries out the signal emission at the antenna of this branch road correspondence.

According to a further aspect of the invention, also provide a kind of CDMA demodulation method of using many yards multicarriers of Space Time Coding, this method comprises: step 1 ' and, the signal of any one reception antenna is carried out following many yards multicarrier demodulation; Step 2 ', respectively the g strip tributary signal of a f step 1 ' output is delivered to follow-up g bar branch road, wherein, 1≤f≤M; 1≤g≤M; Step 3 ', through the Space Time Coding decoder, and the estimated value of line output M bar data-signal; Step 4 ', through parallel/serial conversion process, export M parallel data stream; Step 5 ', M parallel data carried out parallel/serial conversion, obtain user b _kThe data estimation value.

(3) beneficial effect

In sum, the CDMA modulation/demodulation system of the many yards multicarriers (MC-MC) of application Space Time Coding of the present invention has following beneficial effect:

(1) because every branch road in the multi-carrier CDMA system has been adopted band spectrum modulation and the randomized signal processing structure of waveform, thereby make many yards multicarrier systems improve spreading gain, cause further raising information transmission system user capacity, improved the system spectral resources utilance;

(2) owing in many yards multi-carrier CDMA systems, use Space Time Coding, realize space diversity and frequency diversity, thereby strengthened system's antijamming capability, caused further reduction error rate of system, improved systematic function.

Description of drawings

Figure 1A is the schematic flow sheet of many yards CDMA multiple carrier modulator approaches of the embodiment of the invention;

Figure 1B is the schematic flow sheet of many yards CDMA multiple carrier demodulation methods of the embodiment of the invention;

Fig. 2 be many yards CDMA multiple carrier modulation/demodulation methods of the embodiment of the invention signal to noise ratio and bit error rate relation under different modulating/demodulating patterns performance relatively;

Fig. 3 A is the schematic flow sheet that the embodiment of the invention is used many yards CDMA multiple carrier modulator approaches of space-time block code;

Fig. 3 B embodiment of the invention is used the schematic flow sheet of many yards CDMA multiple carrier demodulation methods of space-time block code;

Fig. 4 is that the embodiment of the invention is used many yards CDMA multiple carrier modulation/demodulation methods of Space Time Coding and the performance comparison of additive method under the same conditions.

Embodiment

For making the purpose, technical solutions and advantages of the present invention clearer, below in conjunction with specific embodiment, and with reference to accompanying drawing, the present invention is described in more detail.Though this paper can provide the demonstration of the parameter that comprises particular value, should be appreciated that parameter need not definitely to equal corresponding value, but can in acceptable error margin or design constraint, be similar to corresponding value.

In many yards CDMA multiple carrier modulator approaches of the present invention and the demodulation method, in conjunction with multi-carrier CDMA system and many spread spectrum codes C DMA modulating system advantage, when improving power system capacity, have higher data transmission capabilities and the lower error rate.In addition, Space Time Coding itself has the advantages such as function of space diversity gain, the present invention has also designed a kind of many yards multi-carrier CDMA systems using Space Time Coding in conjunction with Space Time Coding, further improved systematic function, reduced the error rate, improved the utilance of frequency spectrum resource, in the multiple data service transmission system, be with a wide range of applications.

(1) many yards multicarriers (MC-MC) modulation technique

Modulator approach:

In one exemplary embodiment of the present invention, a kind of CDMA modulator approach of many yards multicarriers has been proposed.In the present embodiment, in conjunction with the advantage of many spreading codes modulating system, by band spectrum modulation and waveform randomization operation, the mutual correlation properties of carrier wave tributary signal have been improved at the front end of common orthogonal frequency multi-carrier modulation technology.

Set up departments the system in K user arranged, each user uses same orthogonal code group W:

W＝{w _i(n)/0＜i≤M} (1)

Figure 1A is the schematic flow sheet of modulated process in many yards CDMA multiple carrier modulation/demodulation methods of the embodiment of the invention.Shown in Figure 1A, this modulator approach comprises:

Step S102, the user data b of user k _kThe process string-and convert the parallel low data flow data b of M bar to _{K, i}(1≤i≤M), b _{K, i}Duration of bits per inch certificate be b _kBit duration M doubly;

Step S104 is the orthogonal sequence w of N with length _{K, i}(1≤i≤M) is the low data flow data b parallel to the M bar respectively _{K, i}Carry out band spectrum modulation, establish b _{K, i}Bit duration be T _s, w _iBit duration be T _c, T _s=NT _c, b then _{K, i}Be equivalent in frequency domain expansion N doubly;

Shown in Figure 1A, in orthogonal frequency division multiplexi, every branch road b after the serial/parallel conversion _{K, i}Being multiplied by length is the orthogonal intersection sequence w of N _{K, i}(1≤i≤M), to obtain spreading gain, realize code division multiplexing.Different orthogonal intersections keeps accurate synchronized relation each other, and then the interference between the sequence is zero.

The sign indicating number sequence of k user's i bar branch road can be written as:

$y_{k,i}\left(t\right)=\underset{q=-\∞}{\overset{+\∞}{\mathrm{\Σ}}}\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{b}_{k,i}\left(q\right)w_{k,i}\left(n\right)h(t-n{T}_c-q{T}_s)---\left(2\right)$

H (t) is defined as in the formula (2):

$h\left(t\right)=\left\{\begin{array}{c}\frac{1}{\sqrt{T_c}},0<t<{\mathrm{<figure-callout\; id="0"\; label="T\; c"\; filenames="HDA0000140057800000011.png,HDA0000140057800000041.png"\; state="\{\{state\}\}">T</figure-callout>}}_c\\ 0,t\&le;0,t\&GreaterEqual;T_c\end{array}\right.---\left(3\right)$

In the formula (2), q and n are just representing a parameter in the temporal information, and represents physical amount not is according to the T of front S104 definition _s=NT _c, h (t-nT so _c-qT _s)=h (t-(qN+n) T _c), be exactly that the system time time-delay is with respect to T (qN+n) _cMultiple, be used for representing a discrete time of m sequence.

Step S106 is with the M bar parallel data addition after the band spectrum modulation, the data y after the addition _k(t) can be expressed as;

$y_k\left(t\right)=\underset{i=1}{\overset{M}{\mathrm{\&Sigma;}}}{y}_{k,i}\left(t\right)=\underset{i=1}{\overset{M}{\mathrm{\&Sigma;}}}\underset{q=-\&infin;}{\overset{\&infin;}{\mathrm{\&Sigma;}}}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{b}_{k,i}\left(q\right)w_{k,i}\left(n\right)h(t-n{T}_c-q{T}_s)---\left(4\right)$

Step S108 copies to L bar orthogonal sub-carriers branch road with the data after the addition;

Step S110, with the data of each branch road again with their cross correlation PN sequence (generally being the m sequence) c preferably _{K, j}(1≤j≤L) multiply each other realizes the randomization of L bar branch road waveform, reduces the tributary signal cross-correlation.

The their cross correlation of most of orthogonal sequences is bad, and this causes system to have big multiple access interference, in order to weaken the multiple access interference that other users produce receiving the user, improves the their cross correlation of orthogonal sequence.Each branch road again with their cross correlation PN sequence c preferably _{K, j}(1≤j≤L) multiply each other establishes c _{K, j}With b _{K, i}Bit duration identical all be T _c, PN sequence c _{K, j}(1≤j≤L) does not play the effect of spread spectrum in native system, it only plays the randomized effect of L bar branch road waveform that makes, and the signal on k user l bar branch road is s _{K, l}(t).

$s_{k,l}\left(t\right)=\underset{i=1}{\overset{M}{\mathrm{\&Sigma;}}}\underset{q=-\&infin;}{\overset{+\&infin;}{\mathrm{\&Sigma;}}}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{b}_{k,i}\left(q\right)w_{k,i}\left(n\right)h(t-n{T}_c-q{T}_s)c_{k,i}(\mathrm{Nq}+n)---\left(5\right)$

Step S112, the data of L bar orthogonal sub-carriers branch road are carried out biphase phase shift keying (Binary Phase Shift Keying, be called for short BPSK) modulation, other digital method also has orthogonal PSK (Quadrature Phase Shift Keying, be called for short QPSK), phase shift keying (Phase Shift Keying is called for short PSK);

Step S114 will carry out the data addition of the L bar orthogonal sub-carriers branch road after biphase phase shift keying is modulated, many yards multi-carrier modulation of realization;

The transmission signal s of user k _k(t) be:

$s_k\left(t\right)=\underset{l=1}{\overset{L}{\mathrm{\&Sigma;}}}\underset{i=1}{\overset{M}{\mathrm{\&Sigma;}}}\underset{q=-\&infin;}{\overset{+\&infin;}{\mathrm{\&Sigma;}}}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{b}_{k,i}\left(q\right)w_{k,i}\left(n\right)h(t-n{T}_c-q{T}_s)c_{k,l}(\mathrm{Nq}+n)\cos ({\mathrm{\&omega;}}_{l}t+{\mathrm{\&theta;}}_{k,l})---\left(6\right)$

ω _tThe last sub-carrier frequencies of representing l bar branch road, θ _{K, l}The random phase of the subcarrier on the l bar branch road of expression user k, θ _{K, l}Be the even distribution on [0,2 π], L represents sub-carrier number.

Demodulation method:

Transmitting of MC-MC-CDMA is made up of the subcarrier of many arrowbands, and what can be similar to thinks that its every subchannel all is a Rayleigh attenuation channel, and the impulse response of every subchannel can be written as

$h_{k,l}\left(t\right)={\mathrm{\&beta;}}_{k,l}\left(t\right)e^{j{\mathrm{\&psi;}}_{k,l}\left(t\right)}---\left(7\right)$

h _{K, l}(t) be that an average is zero, variance is σ ²Gaussian random variable, β _{K, l}(t), ψ _{K, l}(t) be path gain and the phase place of k user's l paths respectively.

The signal r (t) that system receives can be written as:

$r\left(t\right)=\underset{l=1}{\overset{L}{\mathrm{\&Sigma;}}}\underset{i=1}{\overset{M}{\mathrm{\&Sigma;}}}\underset{q=-\&infin;}{\overset{+\mathrm{\&omega;}}{\mathrm{\&Sigma;}}}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_{k,l}\left(t\right)b_{k,i}\left(q\right)w_{k,i}\left(n\right)h(t-n{T}_c-q{T}_s)c_{k,l}(\mathrm{Nq}+n)\cos ({\mathrm{\&omega;}}_{1}t+{\mathrm{\&phi;}}_{k,l}\left(t\right))+n\left(t\right)---\left(8\right)$

φ _{K, l}(t)=θ _{K, l}+ ψ _{K, l}(t), n (t) is zero-mean, and power spectral density is N ₀Additive white Gaussian noise, suppose at the time interval [0, T _c) last k user's the path gain β of l paths _{K, l}(t) and phase place ψ _{K, l}(t) be a constant.

The demodulating process of system is actually an inverse process of modulated process, and therefore, the adjustment content in the above-mentioned many yards multi-carrier modulations also is an important adjustment content of demodulation mode.Figure 1B is the flow chart of demodulating process in the CDMA demodulation/demodulation method of many yards multicarriers of the embodiment of the invention.As shown in Figure 1B, this demodulation method comprises:

Step S150 carries out the FFT conversion to the received signal, generates parallel L road signal;

Step S152 carries out carrier wave demodulation to each the bar branch road in the described parallel L road signal, and the signal after the demodulation is:

$r_1\left(t\right)=\underset{l=1}{\overset{L}{\mathrm{\&Sigma;}}}\underset{i=1}{\overset{M}{\mathrm{\&Sigma;}}}\underset{q=-\&infin;}{\overset{+\&infin;}{\mathrm{\&Sigma;}}}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_{k,l}\left(t\right)b_{k,i}\left(q\right)w_{k,i}\left(n\right)h(t-n{T}_c-q{T}_s)c_{k,l}(\mathrm{Nq}+n){\cos }^2({\mathrm{\&omega;}}_{l}t+{\mathrm{\&phi;}}_{k,l}\left(t\right))+n\left(t\right)\cos ({\mathrm{\&omega;}}_{l}t+{\mathrm{\&phi;}}_{k,l}\left(t\right))---\left(9\right)$

Step S154 carries out low-pass filtering to the data of carrying out behind the carrier wave demodulation, peels off carrier wave, receives signal and becomes:

$r_2\left(t\right)=\frac{1}{2}\underset{l=1}{\overset{L}{\mathrm{\&Sigma;}}}\underset{i=1}{\overset{M}{\mathrm{\&Sigma;}}}\underset{q=-\&infin;}{\overset{+\&infin;}{\mathrm{\&Sigma;}}}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_{k,l}\left(t\right)b_{k,i}\left(q\right)w_{k,i}\left(n\right)h(t-n{T}_c-q{T}_s)c_{k,l}(\mathrm{Nq}+n)---\left(10\right)$

Step S156 carries out despreading by the integration differentiation to each the bar branch road in the parallel L road signal, peels off PN sequence c _{K, j}(1≤j≤L), to eliminate emission modulating part m sequence to the randomization of primary data information (pdi) waveform, this moment, signal became:

$r_3\left(t\right)=\frac{1}{2}\underset{l=1}{\overset{L}{\mathrm{\&Sigma;}}}\underset{i=1}{\overset{M}{\mathrm{\&Sigma;}}}\underset{q=-\&infin;}{\overset{+\&infin;}{\mathrm{\&Sigma;}}}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_{k,l}\left(t\right)b_{k,i}\left(q\right)w_{k,i}\left(n\right)h(t-n{T}_c-q{T}_s)---\left(11\right)$

Step S158, data after the PN sequence are carried out parallel/serial conversion and sampling keeps handling to peeling off, and to have reduced quantizing noise, have strengthened noiseproof feature.

Step S160 carries out despreading by the integration differentiation to every branch road to the data after the sampling maintenance processing, peels off spreading code, thereby obtain signal is:

$r_4\left(t\right)=\frac{1}{2}\underset{l=1}{\overset{L}{\mathrm{\&Sigma;}}}\underset{i=1}{\overset{M}{\mathrm{\&Sigma;}}}\underset{q=-\&infin;}{\overset{+\&infin;}{\mathrm{\&Sigma;}}}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{\mathrm{\&beta;}}_{k,l}\left(t\right)b_{k,i}\left(q\right)h(t-n{T}_c-q{T}_s)---\left(12\right)$

Owing in the transmitting terminal modulation, in order to increase spreading gain, reduce user data and disturb, add spreading code and carry out spread processing, this step is corresponding with the transmitting terminal chopping phase.

Step S162 carries out serial/parallel conversion to the data of peeling off spreading code, obtains final signal

Fig. 2 is the analogous diagram of many yards multi-carrier CDMA systems of embodiment of the invention signal to noise ratio and bit error rate relation under different modulating/demodulating patterns.As shown in Figure 2, when getting K and be 10, for the MC-MC-CDMA system, sub-carrier number L is 4, and the number M of sign indicating number is respectively 2,4,8; For multi-carrier CDMA system, sub-carrier number L is 16; For many yards cdma systems, the number M of sign indicating number is 16.

By present embodiment as can be seen, the orthogonal frequency-division multiplex multi-carrier modulation method that the present embodiment modulation-demo-demodulation method is more common has further strengthened the anti-multipath interference performance, has lowered error rate of system, improve frequency spectrum resource utilization rate, improved the performance of the information transmission system.

(2) many yards multi-carrier modulation technologies of application Space Time Coding

Because Space Time Coding is subjected to certain restriction in the use, that is: it can only be applicable to flat fading channel, and can not be applicable to frequency-selective channel.Main characteristics of multi-carrier OFDM modulation technique are the technology that the frequency selective channel can be changed into flat fading channel, well solved the suitable requirement of Space Time Coding, for this reason, a kind of many yards CDMA multiple carrier modulating/demodulating technology using Space Time Coding have been designed on the basis of above-described embodiment.In the present embodiment, after the serial/parallel variation of signal, by the space-time block code device and then carry out many yards multi-carrier modulation, by many antennas outputs, transmit at last.Optimal design a kind of many yards CDMA multiple carrier modulation/demodulation systems using Space Time Coding.

Modulator approach:

Set up departments the system in K user arranged, each user uses same orthogonal code group W:

W＝{w _i(n)/0＜i≤M} (13)

Fig. 3 A is the schematic flow sheet that the embodiment of the invention adopts modulated process in the many yards CDMA multiple carrier modulation/demodulation methods of Space Time Coding.As shown in Figure 3A, this modulator approach comprises:

Step S302, the user data b of user k _kThrough after the serial/parallel conversion, convert the parallel low data flow b of M bar to _{K, i}(1≤i≤M), wherein a branch road b _{K, i}Duration of bits per inch certificate be b _kBit duration M doubly.This step is identical with step S102.

Step S304, each the bar branch road b in the low data flow that the M bar walks abreast _{K, i}Data carry out space-time block code respectively.N in the present embodiment _T=M, the code word size of empty time-code are M, and each empty time-code comprises n _T* M=M * M code sign, crack at a time, the Space Time Coding device is to b _{K, i}The input the data information bits sequence encode output code word be:

The space-time block code device is at first with b _{K, i}Data be divided into M group, every group of sequence length is M, is the symbol of element x of sending metrix by the modulated symbol constellation mapping with the M group data stream then _{M, q}, (m=1,2 ..., M, q=1,2 ..., M), (the bar branch road of 1≤q≤M) is at m (1≤m≤M) send x in the individual time slot for q _{M, q}(m=1,2 ..., M, q=1,2 ..., M) the individual symbol of element.

Step S306, ((the strip tributary signal of 1≤q≤M) is delivered to follow-up q, and ((1≤p≤M) bar is imported sub-branch road to the individual subsequent step p of 1≤q≤M) to the q of the individual Space Time Coding device output of 1≤p≤M) with p respectively;

Step S308, the parallel processing procedure to M bar branch road execution in step S104～S112;

For each bar branch road, this step specifically comprises:

Step S308A is the orthogonal sequence w of N with length _{K, i}The low data flow b parallel to the M bar respectively _{K, i}Carry out band spectrum modulation, wherein, 1≤i≤M;

Step S308B is with the M bar parallel data addition after the band spectrum modulation;

Step S308C copies to L bar orthogonal sub-carriers branch road with the data after the addition;

Step S308D, to the data of each branch road in the described L bar orthogonal sub-carriers branch road with

PN sequence c _{K, j}Multiply each other, wherein, 1≤j≤L;

Step S308E carries out the numeral modulation to the data of each branch road in the described L bar orthogonal sub-carriers branch road.

Step S310 carries out parallel/serial conversion to the data of M bar branch road respectively, carries out the signal emission at corresponding antenna, u antenna transmit into:

$x_u\left(t\right)=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}\underset{w=1}{\overset{W}{\mathrm{\&Sigma;}}}\underset{j=1}{\overset{M}{\mathrm{\&Sigma;}}}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}\underset{l=1}{\overset{L}{\mathrm{\&Sigma;}}}\underset{q=-\&infin;}{\overset{+\&infin;}{\mathrm{\&Sigma;}}}{x}_{u,w}^{(k,n)}{w}_{k,j}\left(n\right)h(t-n{T}_c-w{T}_s)c_{k,l}(\mathrm{Nq}+n)e^{i{\mathrm{\&omega;}}_l(t-n{T}_c-w{T}_s)}---\left(15\right)$

In the formula (15),

Be u (1≤u≤n _T) individual antenna n (sends the mark of W signal on the individual subcarrier of 1≤n≤M).

Demodulation method:

Transmitting antenna u can be expressed as to the channel pulse transmission response of reception antenna v:

$h_{u,v}(t,\mathrm{\&tau;})=\underset{l}{\mathrm{\&Sigma;}}{\mathrm{\&gamma;}}_{u,v}(t,l)\mathrm{\&delta;}(\mathrm{\&tau;}-{\mathrm{\&tau;}}_l)---\left(16\right)$

In the formula (16), τ _lAnd γ _{U, v}(t l) is time delay and the amplitude of l paths; n _v(t) be white Gaussian noise.

In many yards multi-carrier CDMA systems using Space Time Coding, the signal that reception antenna is received is n _TThe road transmits and forms signal through the stack of the signal after decline and the noise jamming, and its expression formula is:

$r_v\left(t\right)=\underset{u=1}{\overset{n_T}{\mathrm{\&Sigma;}}}{\&Integral;}_{-\&infin;}^{+\&infin;}{x}_u(t-\mathrm{\&tau;})h_{u,v}(t,\mathrm{\&tau;})\mathrm{d\&tau;}+n_v\left(t\right)---\left(17\right)$

In the formula (17), h _{U, v}(t τ) is the channel pulse transmission response of transmitting antenna u to reception antenna v.

In one exemplary embodiment of the present invention, also proposed to use the cdma system demodulation method of many yards multicarriers of Space Time Coding.Fig. 3 B is the schematic flow sheet that the embodiment of the invention adopts demodulating process in the many yards CDMA multiple carrier modulation/demodulation methods of Space Time Coding.Concrete demodulation mode is an inverse process of modulation system.Present embodiment also comprises:

Step S352 carries out the many yards multicarrier demodulating processes of step S150～S160 to the signal of any one reception antenna;

$r_{v1}\left(t\right)=\underset{u=1}{\overset{n_T}{\mathrm{\&Sigma;}}}{\&Integral;}_{-\&infin;}^{+\&infin;}\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}\underset{w=1}{\overset{W}{\mathrm{\&Sigma;}}}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}\underset{l=1}{\overset{L}{\mathrm{\&Sigma;}}}{x}_{u,w}^{(k,n)}h(t-\mathrm{\&tau;}-n{T}_c-w{T}_s)h_{u,v}(t,\mathrm{\&tau;})\mathrm{d\&tau;}+n_v\left(t\right)---\left(18\right)$

For one of them reception antenna, this step specifically comprises:

Step 352A ' carries out the FFT conversion to the received signal, generates parallel L road signal;

Step 352B ' carries out carrier wave demodulation to each the bar branch road in the described parallel L road signal;

Step 352C ' carries out low-pass filtering to the data of carrying out behind the carrier wave demodulation, peels off carrier wave;

Step 352D ' carries out despreading by the integration differentiation to each the bar branch road in the parallel L road signal, peels off the PN sequence;

Step 352E ', data after the PN sequence are carried out parallel/serial conversion and sampling keeps handling to peeling off;

Step 352F ' carries out despreading by the integration differentiation to every branch road to the data after the sampling maintenance processing, peels off spreading code;

Step S354, ((the strip tributary signal of 1≤g≤M) is delivered to follow-up g (the bar branch road of 1≤g≤M) to the g of the individual step S352 output of 1≤f≤M) with f respectively;

Step S356, through the Space Time Coding decoder, and the estimated value of line output M bar data-signal;

Step S358 through parallel/serial conversion process, exports M parallel data stream b _{K, i}(1≤i≤M);

Step S360 carries out parallel/serial conversion to M parallel data, and output obtains user b _kThe data estimation value.

Use in the many yards multi-carrier CDMA systems of Space Time Coding, select the Walsh sign indicating number as spreading code, spreading gain is 32, and sub-carrier number L is 32, and all user profile emitted energies are identical.Modulation system is QPSK, and wireless channel is the Reyleigh path that independently declines, 2 footpath, and maximum Doppler frequency is 20Hz.When taking amount K=12 and K=32, suppose that they take identical bandwidth, identical signal source, identical information rate, to the performance of the MC-MC-CDMA systematic function of using Space Time Coding and common MC-MC-CDMA system, and the performance of using the multi-carrier CDMA system of Space Time Coding compares.

The analogous diagram of the many yards multi-carrier CDMA systems that Fig. 4 uses Space Time Coding for the embodiment of the invention signal to noise ratio and bit error rate relation under different modulating/demodulating patterns.As shown in Figure 4, as shown in Figure 4, lowermost that line is many yards multi-carrier CDMA systems in conjunction with Space Time Coding, the error rate is minimum, the multi-carrier CDMA system error rate that middle that toe-in closes Space Time Coding is taken second place, uppermost that line is many yards multi-carrier CDMA systems in the embodiment of the invention, and its error rate is not low in conjunction with the system of Space Time Coding.

Because adopted the core technology Space Time Coding among the MIMO (multi-input multi-output system), further improve system spectral resources utilance and system user capacity thereby make system obtain bigger frequency spectrum diversity and space diversity.The performance that the present invention uses many yards multi-carrier modulation/demodulating systems of Space Time Coding further improves, and obtains bigger system user capacity, higher frequency spectrum resource utilization rate.

More than technology contents involved in the present invention has been carried out sufficient argumentation, still, for known some technology contents in the communications field, as the detailed process that Space Time Coding, parallel/serial conversion etc. are handled, the present invention does not have too much giving unnecessary details.In addition, in some step, just describe its modulated process in detail, corresponding demodulating process is not launched in detail, and this demodulating process should be the inverse process of this modulated process.For the those of ordinary skill of the communications field, should fully understand and implement the present invention according to the relevant record of specification.

Above-described specific embodiment; purpose of the present invention, technical scheme and beneficial effect are further described; institute is understood that; the above only is specific embodiments of the invention; be not limited to the present invention; within the spirit and principles in the present invention all, any modification of making, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (11)

1. the CDMA modulator approach of many yards multicarriers is characterized in that, comprising:

Steps A, k user data of users b _kThe process string-and convert the parallel data flow b of M bar to _{K, i}, wherein, i=1,2 ..., M;

Step B is the orthogonal sequence w of N with length _{K, i}The data flow b parallel to the M bar respectively _{K, i}Carry out band spectrum modulation;

Step C is with the M bar parallel data addition after the band spectrum modulation;

Step D copies to L bar orthogonal sub-carriers branch road with the data after the addition;

Step e is to data and the PN sequence c of each bar branch road in the described L bar orthogonal sub-carriers branch road _{K, j}Multiply each other, wherein, j=1,2 ..., L;

Step F is carried out the numeral modulation to the data of each bar branch road in the described L bar orthogonal sub-carriers branch road;

Step G will carry out the data addition of the L bar orthogonal sub-carriers branch road after numeral is modulated, many yards multi-carrier modulation of realization.

2. the CDMA modulator approach of many yards multicarriers according to claim 1 is characterized in that, the sign indicating number sequence of k user's i bar branch road through after the band spectrum modulation is among the described step B:

$y_{k,i}\left(t\right)=\underset{q=-\&infin;}{\overset{+\&infin;}{\mathrm{\&Sigma;}}}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{b}_{k,i}\left(q\right)w_{k,i}\left(n\right)h(t-n{T}_c-q{T}_s)$

Wherein, $h\left(t\right)=\left\{\begin{array}{c}\frac{1}{\sqrt{T_c}},0<t<T_c\\ 0,t\&le;0,t\&GreaterEqual;T_c\end{array}\right.,$ T _cBe orthogonal sequence w _{K, i}Bit duration, T _sBe data flow b _{K, i}Bit duration.

3. the CDMA modulator approach of many yards multicarriers according to claim 1 is characterized in that, in the described step e, after the sign indicating number sequence of k user's the l bar branch road process waveform randomization is:

$s_{k,l}\left(t\right)=\underset{i=1}{\overset{M}{\mathrm{\&Sigma;}}}\underset{q=-\&infin;}{\overset{+\&infin;}{\mathrm{\&Sigma;}}}\underset{n=0}{\overset{N-1}{\mathrm{\&Sigma;}}}{b}_{k,i}\left(q\right)w_{k,i}\left(n\right)h(t-n{T}_c-q{T}_s)c_{k,l}(\mathrm{Nq}+n).$

4. according to the CDMA modulator approach of each described many yards multicarriers in the claim 1 to 3, it is characterized in that in the described step F, described numeral is modulated to: biphase phase shift keying modulation, orthogonal PSK or phase shift keying.

5. according to the CDMA modulator approach of each described many yards multicarriers in the claim 1 to 3, it is characterized in that in the described step e, described PN sequence is the m sequence.

6. the CDMA demodulation method of many yards multicarriers is characterized in that, is used for the data that adopt each described many yards CDMA multiple carrier modulator approaches of claim 1 to 3 to modulate are carried out demodulation, comprising:

Steps A ', carry out the FFT conversion to the received signal, generate parallel L road signal;

Step B ' carries out carrier wave demodulation to each the bar branch road in the described parallel L road signal;

Step C ' carries out low-pass filtering to the data of carrying out behind the carrier wave demodulation, peels off carrier wave;

Step D ' carries out despreading by the integration differentiation to each the bar branch road in the parallel L road signal, peels off the PN sequence;

Step e ', data after the PN sequence are carried out parallel/serial conversion and sampling keeps handling to peeling off;

Step F ', the data after the sampling maintenance processing are carried out despreading by the integration differentiation to every branch road, peel off spreading code;

Step G carries out serial/parallel conversion to the data of peeling off spreading code, obtains the user data b after the demodulation _k

7. a CDMA modulator approach of using many yards multicarriers of Space Time Coding is characterized in that, comprising:

Step S1, the user data b of user k _kThe process string-and convert the parallel data flow b of M bar to _{K, i}, wherein, 1≤i≤M;

Step S2, each the bar branch road b in the data flow that the M bar walks abreast _{K, i}Data carry out space-time block code respectively, output M bar branch road;

Step S4 delivers to the q strip tributary signal of p Space Time Coding device output q follow-up subsequent step p bar input branch road respectively, wherein, p=1,2 ..., M; Q=1,2 ..., M;

Step S5, parallel carries out many yards multi-carrier modulation to M bar branch road;

Step S6 carries out parallel/serial conversion to the data of the L bar branch road of many yards multi-carrier modulation output respectively, and carries out the signal emission at the antenna of this branch road correspondence.

8. the CDMA demodulation method of many yards multicarriers of application Space Time Coding according to claim 7 is characterized in that, each the bar branch road b in the data flow that the M bar walks abreast among the described step S2 _{K, i}Data carry out space-time block code respectively, output M bar branch road comprises:

With b _{K, i}Data be divided into M group, every group of sequence length is M;

Be respectively the symbol of element x of sending metrix by the modulated symbol constellation mapping with the M group data stream _{M, q}

Q bar branch road sends x in m time slot _{M, q}The individual symbol of element;

Wherein, in the above steps, m=1,2 ..., M, q=1,2 ..., M.

9. the CDMA demodulation method of many yards multicarriers of application Space Time Coding according to claim 7 is characterized in that, parallel many yards multi-carrier modulation of M bar branch road execution are comprised among the described step S5:

Step S5A is the orthogonal sequence w of N with length _{K, i}The data flow b parallel to the M bar respectively _{K, i}Carry out band spectrum modulation;

Step S5B is with the M bar parallel data addition after the band spectrum modulation;

Step S5C copies to L bar orthogonal sub-carriers branch road with the data after the addition;

Step S5D is to data and the PN sequence c of each branch road in the described L bar orthogonal sub-carriers branch road _{K, j}Multiply each other, wherein, 1≤j≤L;

Step S5E carries out the numeral modulation to the data of each branch road in the described L bar orthogonal sub-carriers branch road.

10. a CDMA demodulation method of using many yards multicarriers of Space Time Coding is characterized in that, is used for the data that many yards CDMA multiple carrier modulator approaches that adopt each described application Space Time Coding of claim 7 to 9 are modulated are carried out demodulation, comprising:

Step S1 ' carries out many yards multicarrier demodulating processes to the signal of any one reception antenna;

Step S2 ' delivers to follow-up g bar branch road with the g strip tributary signal of a f step 1 ' output respectively, wherein, and 1≤f≤M; 1≤g≤M;

Step S3 ', through the Space Time Coding decoder, and the estimated value of line output M bar data-signal;

Step S4 ' through parallel/serial conversion process, exports M parallel data stream;

Step S5 ' carries out parallel/serial conversion to M parallel data, obtains user b _kThe data estimation value.

11. the CDMA demodulation method of many yards multicarriers of application Space Time Coding according to claim 10, wherein, described step S1 ' carries out many yards multicarrier demodulating processes to the signal of any one reception antenna and comprises:

Step 1 ' A ' is carried out the FFT conversion to the received signal, generates parallel L road signal;

Step S1 ' B ' carries out carrier wave demodulation to each the bar branch road in the described parallel L road signal;

Step S1 ' C ' carries out low-pass filtering to the data of carrying out behind the carrier wave demodulation, peels off carrier wave;

Step S1 ' D ' carries out despreading by the integration differentiation to each the bar branch road in the parallel L road signal, peels off the PN sequence;

Step S1 ' E ', data after the PN sequence are carried out parallel/serial conversion and sampling keeps handling to peeling off;

Step S1 ' F ' carries out despreading by the integration differentiation to every branch road to the data after the sampling maintenance processing, peels off spreading code.

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