CN101325442A - Multi-antenna system and data transmission method thereof - Google Patents

Abstract

The invention relates to a wireless communication system, which discloses a multi-antenna system and a data transmitting method. In the invention, the plural phase sequence in the MIMO precoding system of CDD is improved, to cause the phase shift in the whole system bandwidth equal to CDD, meanwhile the variable step of the plural phase sequence is set to be equal to the corresponding sub-carrier of the precoding feedback bandwidth, thereby keeping higher precoding performance when the feedback bandwidth is greater relative to the whole frequency band ratio. The virtual cycle time delay can be changed along the time, thereby obtaining the diversity effect on the time. When the channel frequency has small selectivity, the virtual cycle time delay makes the minimum to obtain the dispatching gain.

Description

Multiaerial system and data transmission method for uplink thereof

Technical field

The present invention relates to wireless communication field, particularly the lift-off technology of multiple-input and multiple-output (Multiple InputMultiple Output is called for short " MIMO ") system.

Background technology

Along with the development of wireless mobile communications, two major techniques have been proposed in recent years: multi-carrier OFDM (Orthogonal Frequency Division Multiplexing is called for short " OFDM ") technology and MIMO technology.Because multipath characteristics that can overcome wireless channel well that the OFDM technology is had and the characteristics higher than single carrier frequency spectrum efficiency, and, the characteristics of spectrum efficiency that can increase wireless communication system that the MIMO technology is had and raising reliability; Make mutually combining of these two kinds of technology become the key technology in the mobile communication system.

Respectively these two kinds of technology are simply introduced below.

The transmitting terminal theory diagram of a simple single-antenna transmission ofdm system comprises chnnel coding, constellation mapping, subcarrier mapping, OFDM modulation, adds Cyclic Prefix (Cyclic Prefix is called for short " CP "), sends these several parts as shown in Figure 1.The ofdm system receiving terminal theory diagram that this single antenna receives comprises that time-domain signal receives, goes CP, OFDM demodulation, separates mapping, channel estimating, equilibrium, constellation mapping, these several parts of channel decoding as shown in Figure 2.

The MIMO technology is exactly to settle a plurality of antennas to transmit and receive respectively at the transmitting terminal of communication system and receiving terminal, and the MIMO technology mainly can be divided into two classes.When there are a plurality of transmitting antennas in transmitting terminal or receiving terminal, and during the identical data of each antenna emission, the signal that receiving terminal can obtain a plurality of branches merges, and improves the reliability of transmission, and we are called the multi-antenna diversity technology with the MIMO technology of this class.In addition, when there are a plurality of antenna in transmitting terminal and receiving terminal simultaneously, because mimo channel can equivalence become a plurality of parallel channels, so the transmitting terminal transmission multichannel data that can walk abreast simultaneously, thereby can improve transmission rate, we are called space multiplexing technique with the technology of this class.

Cyclic Delay Diversity (Cyclic Delay Diversity, be called for short " CDD ") be a kind of multiple antennas transmit diversity scheme commonly used in the ofdm system, send identical frequency domain data on each antenna and the OFDM symbol of time domain is carried out different circulation delays, obtain frequency diversity gain with this.The transmitting terminal theory diagram of employing CDD emission as shown in Figure 3.

As can be seen from Figure 3, all adopted different circulation delay D on each antenna _m, m=1,2 ... M.Suppose the symbol of X (k) expression frequency domain, the sampling point of x (n) expression time domain can be known according to the character of discrete Fourier transform (DFT) (DiscreteFourier Transform is called for short " DFT "), circulation delay on the time domain is equivalent to the phase shift on the frequency domain, thereby can obtain following formula: $\mathrm{DFT}\left[x{\left((n-D)\right)}_N\right]=X\left(k\right)e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="A20071012618100201.png,A20071012618100221.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{2\mathrm{\&pi;kD}}{N}};$ Wherein N represents counting of DFT, and k represents the numbering of subcarrier, k=0, and 1,2 ..., N-1.

The frequency-region signal that receives can be expressed as:

$Y\left(k\right)=\underset{m=1}{\overset{M}{\mathrm{\&Sigma;}}}{H}_m\left(k\right)X\left(k\right)e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="A20071012618100201.png,A20071012618100221.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{2\mathrm{\&pi;k}{D}_m}{N}}+N\left(k\right)=X\left(k\right)\underset{m=1}{\overset{M}{\mathrm{\&Sigma;}}}{H}_m\left(k\right)e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="A20071012618100201.png,A20071012618100221.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{2\mathrm{\&pi;k}{D}_m}{N}}+N\left(k\right),k=0,\&CenterDot;\&CenterDot;\&CenterDot;N-1$

Wherein Y (k) expression is received signal on k subcarrier, H _m(k) Biao Shi m transmitting antenna on k subcarrier is to domain channel response between the reception antenna.What N (k) represented is additive white Gaussian noise.

Finding out from the result of following formula, can be the multiaerial system equivalence of adopting CDD a single aerial system a: Y (k)=H _e(k) X (k)+N (k), k=0 ... N-1,

Its equivalent channel is: $H_e\left(k\right)=\underset{m=1}{\overset{M}{\mathrm{\&Sigma;}}}{H}_m\left(k\right)e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="A20071012618100201.png,A20071012618100221.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{2\mathrm{\&pi;k}{D}_m}{N}},k=0,\&CenterDot;\&CenterDot;\&CenterDot;N-1$

As can be seen from the above equation, equivalent channel is that a plurality of channels are multiplied by different phase shifts stack afterwards, and the effect of stack is to make that the speed of channel fluctuation increases.Suppose that for single footpath channel, there is flat decline in channel on frequency domain, the amplitude of the equivalent channel of the single-antenna transmission of this channel and double antenna CDD emission as shown in Figure 4.

Channel has increased in the fluctuation of frequency domain after as can be seen from Figure 4 introducing CDD, just can obtain frequency diversity gain by on frequency domain data being carried out chnnel coding, thereby improves the reliability of transmission.

MIMO precoding (MIMO precoding) is a kind of space multiplexing technique commonly used in the ofdm system, improves transmission rate by send multichannel data simultaneously on a plurality of transmitting antennas.Precoding is the meaning of precoding, (or claiming weighting) the just emission afterwards of just will encoding to data.With two transmitting antennas, two reception antennas is example, and the emission principle figure of MIMO precoding as shown in Figure 5.

As can be seen from Figure 5 the frequency domain data symbol through emission after the precoding can be expressed as:

$\left[\begin{array}{c}{y}_1\left(n\right)\\ y_2\left(n\right)\end{array}\right]=\left[\begin{array}{cc}{w}_{11}& w_{12}\\ w_{21}& w_{22}\end{array}\right]\left[\begin{array}{c}{x}_1\left(n\right)\\ x_2\left(n\right)\end{array}\right],$ Here we usually will $W=\left[\begin{array}{cc}{w}_{11}& w_{12}\\ w_{21}& w_{22}\end{array}\right]$ Be called the precoding matrix.Through after the channel, the frequency-region signal that receiving terminal receives can be expressed as:

$\left[\begin{array}{c}{r}_1\left(n\right)\\ r_2\left(n\right)\end{array}\right]=\left[\begin{array}{cc}{h}_{11}& h_{12}\\ h_{21}& h_{22}\end{array}\right]\left[\begin{array}{c}{y}_1\left(n\right)\\ y_2\left(n\right)\end{array}\right]$

$=\left[\begin{array}{cc}{h}_{11}& h_{12}\\ h_{21}& h_{22}\end{array}\right]\left[\begin{array}{cc}{w}_{11}& w_{12}\\ w_{21}& w_{22}\end{array}\right]\left[\begin{array}{c}{x}_1\left(n\right)\\ x_2\left(n\right)\end{array}\right],$

$=\mathrm{HWX}$

H wherein _Ij, i, j=1,2 expression reception antenna i are to the domain channel response between the transmitting antenna j.We can carry out singular value decomposition (Sigular ValueDecomposition is called for short " SVD "), H=UDV to channel matrix H ^H

U wherein, V is a unitary matrice, and D is a diagonal matrix, and the element of diagonal matrix is exactly the channel gain of mimo channel subchannel.If precoding matrix W=V can be set, so because V is a unitary matrice, so HW=UDV ^HV=UD.As long as this moment the receiving terminal matrix U ^HBe weighted to the received signal, just can obtain multichannel does not have interference signals.

Z＝U ^HHWX＝U ^HUDX＝DX

Therefore as can be seen, the benefit of signal being carried out the precoding weighting just is and can reduces each road interference between signals signal map to the subchannel of each quadrature.

Introduced a kind of scheme that CDD and MIMO precoding are combined in the prior art, we are referred to as CDD precoding here, are example with two transmitting antennas, two reception antennas, and its transmitting terminal schematic diagram as shown in Figure 6.As can be seen from Figure 6, first antenna is not done circulation delay, and promptly circulation delay is zero.Suppose that second circulation delay on the antenna is d, from the discussion of front as can be known, the frequency-region signal that CDD precoding is sent can be expressed as so: $\left[\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="y"\; filenames="A20071012618100201.png,A20071012618100221.png"\; state="\{\{state\}\}">y</figure-callout>}}_1^{\&prime;}\left(n\right)\\ {\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="A20071012618100201.png,A20071012618100221.png"\; state="\{\{state\}\}">y</figure-callout>}}_2^{\&prime;}\left(n\right)\end{array}\right]=\left[\begin{array}{cc}1& 0\\ 0& e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="A20071012618100201.png,A20071012618100221.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{2\mathrm{\&pi;kd}}{N}}\end{array}\right]\left[\begin{array}{cc}{w}_{11}& w_{12}\\ w_{21}& w_{22}\end{array}\right]\left[\begin{array}{c}{x}_1\left(n\right)\\ x_2\left(n\right)\end{array}\right],$ Wherein the definition of k and N is all with as described above identical.

In ofdm system, be divided into the experimental process carrier wave owing to whole frequency band, and can give different users different subcarrier allocation, therefore the frequency domain dispatching technology is widely used in ofdm system, promptly when communicate by letter simultaneously with a plurality of users in the base station, each user is always dispatched top-quality that section resource of respective channels give it.Because each user's channel difference, the best resource of channel quality can not repeat on very big possibility, therefore so can take what one needs.By dispatching the throughput that can effectively improve whole system, we are called multi-user diversity gain or scheduling gain with this gain.Yet when the multipath number of channel was fewer, corresponding frequency domain channel fluctuation may be very little, the channel quality of user on whole frequency band is all similar, is unfavorable for multi-subscriber dispatching like this, by introducing the CDD technology, can increase the fluctuation of channel, make it possible to carry out better frequency domain dispatching.

Yet, be not that channel fluctuation is big more favourable more to frequency domain dispatching.Usually when carrying out frequency domain dispatching, whole frequency band being divided into some groups of subcarriers, is that unit is dispatched with the group, one group of subcarrier is called Resource Block here.Therefore several best Resource Block of scheduling its channel quality of time-division provisioned user wish that channel quality is approaching in a Resource Block, and the fluctuation of channel is less.This just need be controlled at the time delay value in the smaller scope when introducing the CDD technology, to guarantee promptly can increase the fluctuation of channel, can not make that again violent variation takes place channel in a Resource Block.

Prior art hour is prolonged CDD and just can be increased scheduling and gain by introducing, and can not cause very big influence to performance for estimating channel.CDD and MIMO precoding are combined, wish exactly under the fewer channel of channel multi-path number, can increase multi-user diversity gain and obtain the MIMO gain.

We wish that weighting matrix W can equal the matrix V that channel decomposing goes out as far as possible when carrying out MIMO precoding in the prior art, but adopting Frequency Division Duplexing (FDD) (Frequency Division Duplex, abbreviation " FDD ") in the wireless communication system, usually transmitting terminal can't obtain the information of channel matrix H, therefore needs receiving terminal to give transmitting terminal with feedback of channel information.In theory, the channel response difference on each subcarrier need be fed back the channel response on each subcarrier respectively, but will bring a large amount of expenses like this, can reduce the efficient of communication system greatly.Owing to exist correlation in adjacent subcarrier upper signal channel response, therefore in order to reduce feedback, only to one group of adjacent channel information of subcarrier feedback, we are called feedback bandwidth with the bandwidth of the correspondence of this group subcarrier here usually.We are desirably within the feedback bandwidth so, and the variation of channel is smaller as far as possible, use identical precoding matrix can obtain more performance like this on this bandwidth, i.e. weighting can be better and channel matched.

The present inventor finds, CDD is equivalent to introduce phase shift to frequency domain channel, can increase the fluctuation of channel at frequency domain, if the fluctuation of channel is too big in feedback bandwidth, will make and well to mate with the channel in the whole feedback bandwidth, cause performance decrease with a precoding matrix.In the prior art, use the phase shift of CDD correspondence on k subcarrier of frequency domain to be

When d=1, to suppose to have 2048 subcarriers on the whole frequency band, feedback bandwidth is 60 subcarriers.We can calculate so, every a subcarrier, the phase shift that the transmitting antenna of having introduced CDD takes place to the channel between the receiving terminal antenna for- ^{2 π}/ ₂₀₄₈≈-0.17 °, same, be that phase shift is-0.17 * 60=-10.2 ° on 60 subcarriers in feedback bandwidth.When bandwidth ratio was big, CDD influence to channel in feedback bandwidth was less as can be seen.But when d=1, suppose whole frequency band only at 128 subcarriers, so the phase shift every a subcarrier correspondence be- ^{2 π}/ ₁₂₈≈-2.81 ° is-2.81 * 60=-168.6 ° in the i.e. phase shift on 60 subcarriers of feedback bandwidth.As seen, when system bandwidth was smaller, CDD influence to channel in feedback bandwidth was bigger, can reduce the performance of precoding.

Summary of the invention

The technical problem underlying that embodiment of the present invention will solve provides a kind of multiaerial system and data transmission method for uplink thereof, still can keep higher precoding performance when making feedback bandwidth with respect to the whole frequency band large percentage.

For solving the problems of the technologies described above, embodiments of the present invention provide a kind of data transmission method for uplink of multiaerial system, comprise the antenna that M is used to launch in this system, and M 〉=2 wherein may further comprise the steps:

Frequency domain data to be sent and pre-coding matrix multiplied each other generates the data of M road through precoding, and the M road is through the data of a precoding corresponding M antenna respectively;

For each antenna, will to should antenna a road through the data map of the precoding part or all of subcarrier in N the subcarrier;

For each antenna, be that ((k's jCf D)+jE) multiplies each other for the plural phase sequence exp of N with the data on N the subcarrier and length, wherein, C and E are real number, f (k, D) be a discontinuous function, k and D be f (k, the D) variable of function, k are the numbering of subcarrier, 0≤k≤N-1, D is the period of change or the step-length of this function, and f after the value of D is determined (k, D) value of function is along with the variation of k every D a saltus step takes place;

For each antenna, the data on N the subcarrier are carried out modulating in OFDM after, by this antenna emission.

Embodiments of the present invention also provide a kind of multiaerial system, comprising:

M the antenna that is used to launch, wherein M 〉=2;

Precoding unit, being used for frequency domain data to be sent and pre-coding matrix multiplied each other generates the data of M road through precoding, and every road is through the data of precoding one in the corresponding M antenna respectively;

M map unit corresponds respectively to M antenna, each map unit be respectively applied for precoding unit output a road through the data map of the precoding part or all of subcarrier in N the subcarrier;

M multiplication unit, correspond respectively to M antenna, each multiplication unit is respectively applied for a map unit is mapped to N data and the length plural phase sequence exp (jCf (k that be N on the subcarrier, D)+jE) multiply each other, wherein, C and E are real number, (k D) is a discontinuous function to f, and k and D are f (k, D) variable of function, k is the numbering of subcarrier, and 0≤k≤N-1, D are the period of change or the step-length of this function, f after the value of D is determined (k, D) value of function is along with the variation of k every D a saltus step takes place;

M OFDM modulating unit corresponds respectively to M antenna, and each OFDM modulating unit is respectively applied for the data of a multiplication unit output are carried out OFDM modulation back by corresponding antenna transmission.

Embodiment of the present invention compared with prior art, the main distinction and effect thereof are:

By at frequency domain with data on the transmitting antenna N subcarrier and plural phase sequence exp (jCf (k, D)+jE) multiply each other, phase shift and the CDD of channel on the whole system bandwidth equated, obtain frequency diversity or multi-subscriber dispatching gain that CDD brings, be arranged to equate by the step-length that plural phase sequence is changed with the subcarrier number of the feedback bandwidth correspondence of precoding, for the MIMO precoding system that uses CDD, can solve the problem of precoding decreased performance under the smaller situation of system bandwidth effectively.

Description of drawings

Fig. 1 is a single-antenna transmission ofdm system transmitting terminal theory diagram in the prior art;

Fig. 2 is that single antenna receives the OFDM system receiving terminal theory diagram in the prior art;

Fig. 3 is a CDD emission principle block diagram in the prior art;

Fig. 4 is the amplitude schematic diagram of the equivalent channel of single-antenna transmission and double antenna CDD emission in the prior art;

Fig. 5 is a MIMO precoding transmitting terminal theory diagram in the prior art;

Fig. 6 is a CDD precoding emission principle block diagram in the prior art;

Fig. 7 is the data transmission method for uplink flow chart according to multiaerial system in the first embodiment of the invention;

Fig. 8 is to be 2.5MHz according to system bandwidth in the first embodiment of the invention, and number of terminals was respectively 1,5,10 o'clock, and the performance of PSD precoding and CDD precoding is schematic diagram relatively;

Fig. 9 is to be 5MHz according to system bandwidth in the first embodiment of the invention, and the UE number was respectively 1,5,10 o'clock, and the performance of PSD precoding and CDD precoding is schematic diagram relatively;

Figure 10 is according to multiaerial system structure chart in the four embodiment of the invention.

Embodiment

For making the purpose, technical solutions and advantages of the present invention clearer, embodiments of the present invention are described in further detail below in conjunction with accompanying drawing.

First embodiment of the invention relates to a kind of data transmission method for uplink of multiaerial system, comprises M the antenna that is used to launch, wherein M 〉=2 in this system.Idiographic flow as shown in Figure 7.

In step 710, with p road frequency domain data symbol to be sent $\left[\begin{array}{c}{x}_1\left(n\right)\\ x_2\left(n\right)\\ .\\ .\\ .\\ x_p\left(n\right)\end{array}\right]$ With pre-coding matrix

Multiplying each other generates the data of M road through precoding, and every road is through the data of precoding one in the corresponding M antenna respectively.

In step 720, for each antenna, will to should antenna a road through the data map of precoding in N the subcarrier partly or entirely.If system only sends a user's data a moment, then this user's data can be mapped in whole N subcarrier; If system will send a plurality of user's data simultaneously, then each user's data can be mapped in the parton carrier wave, for example, and for two users' situation, can in a preceding N/2 subcarrier, shine upon first user's data, second user's data of mapping in N/2 the subcarrier in back.

In step 730,, the plural phase sequence exp (jCf (k that data on the above-mentioned N subcarrier and length are N will be mapped to for each antenna, D)+jE) multiply each other, wherein, C and E are real number, (k D) is a discontinuous function to f, and k and D are f (k, D) variable of function, k is the numbering of subcarrier, and 0≤k≤N-1, D are the period of change or the step-length of this function, (k, D) value of function is along with the variation of k every D a saltus step takes place for f after the value of D is determined.

In concrete the application, ((k D)+jE) can be jCf this plural number phase sequence exp Or

Wherein, m is the sequence number of this antenna, d _mBe the virtual cycle delay on this antenna, B is the subcarrier number of the feedback bandwidth correspondence of this pre-coding matrix precoding, promptly uses the number of the adjacent sub-carrier of identical precoding matrix, and k is the numbering of subcarrier, and 0≤k≤N-1, k are integer,

Expression rounds downwards and rounds up respectively,

Be initial phase.Wherein, M the pairing M of antenna virtual cycle delay d _mIn, have two kinds of different values at least.

With

For example is specifically described, wherein, suppose that initial phase is 0.Frequency-region signal after multiplying each other can be expressed as:

Can know that from background technology the CDD technical equivalences is in being d with time delay _mAntenna on frequency domain data value of being multiplied by of sending be $e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="A20071012618100201.png,A20071012618100221.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{2\mathrm{\&pi;k}{d}_m}{N}},k=\mathrm{0,1},\&CenterDot;\&CenterDot;\&CenterDot;,N$ Phase shift, here can with $\{e^{-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="A20071012618100201.png,A20071012618100221.png"\; state="\{\{state\}\}">j</figure-callout>}\frac{2\mathrm{\&pi;k}{d}_m}{N}},k=\mathrm{0,1},\&CenterDot;\&CenterDot;\&CenterDot;,N\}$ Regard a plural phase sequence as, CDD is equivalent to the data of frequency domain and this plural phase sequence is multiplied each other.

Be with the difference of CDD technology, in the present embodiment, will be mapped to N data and the plural phase sequence on the subcarrier

Multiply each other, as can be seen, when this plural number phase sequence is the integral multiple of the corresponding subcarrier number of feedback bandwidth B at subcarrier subscript k, identical with the corresponding plural phase sequence among the CDD, when k is not the integral multiple of B, close with the corresponding plural phase sequence among the CDD, thus guarantee that phase shift and the CDD of channel on the whole system bandwidth equates in the present embodiment, obtain frequency diversity or multi-subscriber dispatching gain that CDD brings.When k is not the integral multiple of B, because k is rounded after divided by B, make that the plural phase sequence of being taken advantage of is identical, wherein when being designated as iB～(i+1) between the B-1 under subcarrier downwards $i=\mathrm{0,1},\&CenterDot;\&CenterDot;\&CenterDot;,\frac{N}{B},$ Just can take place once to change every B subcarrier plural number phase sequence.That is to say, the step-length that plural phase sequence changes is arranged to equate with the corresponding subcarrier number of the feedback bandwidth of precoding, its plural phase sequence that multiplies each other is identical for each subcarrier in the same feedback bandwidth, thereby for the MIMO precoding system that uses CDD, the channel fluctuation of each subcarrier in the different feedback bandwidth is more obvious, the channel fluctuation of each subcarrier in the same feedback bandwidth is less, thereby can satisfy the demand of frequency domain dispatching better, can solve the problem of precoding decreased performance under the smaller situation of system bandwidth effectively.

The plural number phase sequence is got The time, its effect and plural phase sequence are got

Similar, its difference only is the former for rounding up, and the latter does not repeat them here for rounding downwards.

Need to prove, in the present embodiment with the cycle time-delay d of antenna in the plural phase sequence _mBe called virtual cycle delay, this be because, the frequency-region signal representation formula from step 730 as can be seen, in fact each antenna does not carry out cycle time-delay in the present embodiment, just when B=1, frequency domain is multiplied by corresponding plural phase sequence and is equivalent in time domain and has carried out a cycle time-delay.When B was not equal to 1, being multiplied by corresponding plural phase sequence can not equivalence carry out cycle time-delay for time domain, so be referred to as virtual cycle delay in the present embodiment.

In step 740,, the data on this N subcarrier are carried out the OFDM modulation for each antenna.

In step 750, after adding CP, send by respective antenna through the data of OFDM modulation.

Describe with the effect of concrete example below, still get with plural phase sequence to present embodiment

Initial phase is 0 for example.Suppose to have two transmitting antennas, d on first antenna ₁D on=0, second antenna ₂=1.Have 2048 subcarriers on whole frequency band, feedback bandwidth is under the situation of 60 subcarriers, can calculate, and in the 1st feedback bandwidth (i.e. the 0th～59 subcarrier), the phase shift of introducing on second transmitting antenna is

Since k＜60, therefore

Equal 0, so phase shift also is 0 °.In the 2nd feedback bandwidth (i.e. the 60th～119 subcarrier), corresponding phase shift is

In the 3rd feedback bandwidth (i.e. the 120th～179 subcarrier), corresponding phase shift is

By that analogy.As seen present embodiment can equally with CDD guarantee can introduce 360 ° (d=1) or 720 ° of (d=2) phase shifts on the whole system bandwidth, thereby increases the fluctuation of frequency domain channel, obtains the frequency diversity gain that CDD brings.Simultaneously, can guarantee again not change,, can solve the problem of precoding decreased performance under the smaller situation of system bandwidth effectively to guarantee the performance of precoding in a feedback bandwidth upper signal channel phase place.

As seen, by at frequency domain with data on the transmitting antenna N subcarrier and plural phase sequence

Or

Multiply each other, phase shift and the CDD of channel on the whole system bandwidth equated, obtain frequency diversity or multi-subscriber dispatching gain that CDD brings, by the step-length setting of plural phase sequence variation and the corresponding subcarrier number of feedback bandwidth of precoding are equated, when present embodiment and MIMO precoding in conjunction with the time, can solve effectively CDD and MIMOprecoding in conjunction with the time decreased performance problem under the smaller situation of system bandwidth, brought.

Description for convenience, the scheme that combines with MIMO precoding in the present embodiment is called phase deviation diversity (Phase Shift Diversity, be called for short " PSD ") precoding, the scheme when CDD and MIMO precoding are combined is called CDD precoding.Fig. 8 and Fig. 9 provided respectively when system bandwidth be 2.5 and 5MHz, when number of terminals was respectively 1,5,10, the analogue system of PSD precoding and CDD precoding was relatively.

Ordinate is represented user throughput among two figure, and abscissa is represented throughput of system.50% (being intermediate value) user's average throughput and the throughput of system performance that the solid line representative is the poorest, 5% (being cell edge) user's average throughput and the throughput of system performance that the dotted line representative is the poorest.CDD+Q=5RB represents PSDprecoding, and it is 0 that no CDD represents the time delay value of CDD.Three points on same curve are represented respectively in the sub-district by ordinate to have 1 from big to small, the situation when 5 and 10 users.

From Fig. 8 and Fig. 9 as can be seen, no matter be that system bandwidth is during for 2.5MHz or system bandwidth is when being 5MHz, be at cell edge or get intermediate value, the user is many or after a little while, the PSD precoding of present embodiment is better than CDD precoding on user throughput and two indexs of throughput of system in the sub-district.

Second embodiment of the invention relates to a kind of data transmission method for uplink of multiaerial system equally, and is roughly the same with first execution mode, and its difference is, in the first embodiment, and the M of M antenna correspondence virtual cycle delay d _mDo not change in time, and in the present embodiment, this M virtual cycle delay d _mCan time to time change, thus temporal diversity further obtained, further improved transmission performance.

Third embodiment of the invention relates to a kind of data transmission method for uplink of multiaerial system equally, roughly the same with first execution mode, its difference is, in the present embodiment, under the condition of total bandwidth less than 3 times of channel coherence bandwidths of system, the pairing virtual cycle delay dm of each antenna is 1 or 2, for example under the scene of spaciousness, does not have multipath substantially, main power concentration is on Dan Jing, though multipath is arranged perhaps but time delay between multipath is very little, in this case, with d _mBe set to 1 or 2, make when selectivity of channel frequency hour, virtual circulation delay can be got smaller value, to obtain the scheduling gain.

Four embodiment of the invention relates to a kind of multiaerial system, as shown in figure 10, comprising: M the antenna that is used to launch, wherein M 〉=2; Precoding unit, being used for frequency domain data to be sent and pre-coding matrix multiplied each other generates the data of M road through precoding, every road through the data of precoding respectively to should M in the antenna one; M map unit corresponds respectively to M antenna, each map unit be respectively applied for the output of this precoding unit a road through the data map of the precoding part or all of subcarrier in N the subcarrier; M multiplication unit, correspond respectively to M antenna, each multiplication unit is respectively applied for a map unit is mapped to N data and the length plural phase sequence exp (jCf (k that be N on the subcarrier, D)+jE) corresponding step-by-step is multiplied each other, wherein, C and E are real number, (k D) is a discontinuous function to f, and k and D are f (k, D) variable of function, k is the numbering of subcarrier, and 0≤k≤N-1, D are the period of change or the step-length of this function, f after the value of D is determined (k, D) value of function is along with the variation of k every D a saltus step takes place; M OFDM modulating unit corresponds respectively to M antenna, and each OFDM modulating unit is respectively applied for the data of a multiplication unit output are carried out the OFDM modulation; M CP unit corresponds respectively to M antenna, and each CP unit is respectively applied for the data of an OFDM modulating unit output are added Cyclic Prefix, with the antenna emission of the data through adding Cyclic Prefix by correspondence.

This plural number phase sequence exp (jCf (k D)+jE) can be:

Or

Wherein, m is the sequence number of antenna, d _mBe the virtual cycle delay on the antenna, in the pairing M of this M antenna virtual cycle delay, have two kinds of different values at least, B is the subcarrier number of the feedback bandwidth correspondence of pre-coding matrix, and k is the numbering of subcarrier, 0≤k≤N-1,

Expression rounds downwards and rounds up respectively, Be initial phase.

By at frequency domain with data on the transmitting antenna N subcarrier and plural phase sequence

Or

Multiply each other, phase shift and the CDD of channel on the whole system bandwidth equated, obtain frequency diversity or multi-subscriber dispatching gain that CDD brings, be arranged to equate by the step-length that plural phase sequence is changed with the corresponding subcarrier number of the feedback bandwidth of precoding, for the MIMO precoding system that uses CDD, can solve the problem of precoding decreased performance under the smaller situation of system bandwidth effectively.

Wherein, each multiplication unit can use the d that does not change in time _m, perhaps, each multiplication unit can change d in time _mValue, thereby further obtain temporal diversity, further improved transmission performance.

Under the condition of total bandwidth less than 3 times of channel coherence bandwidths of this system, the pairing virtual cycle delay of each antenna is 1 or 2, thus when selectivity of channel frequency hour, virtual circulation delay can be got smaller value, to obtain the scheduling gain.

In sum, in embodiments of the present invention, by at frequency domain with data on the transmitting antenna N subcarrier and plural phase sequence

Or Multiply each other, phase shift and the CDD of channel on the whole system bandwidth equated, obtain frequency diversity or multi-subscriber dispatching gain that CDD brings, be arranged to equate by the step-length that plural phase sequence is changed with the corresponding subcarrier number of the feedback bandwidth of precoding, for the MIMOprecoding system that uses CDD, can solve the problem of precoding decreased performance under the smaller situation of system bandwidth effectively.

Virtual cycle delay can time to time change, thereby further obtains temporal diversity, has further improved transmission performance.

When selectivity of channel frequency hour, virtual circulation delay can be got smaller value, to obtain the scheduling gain.

Though pass through with reference to some of the preferred embodiment of the invention, the present invention is illustrated and describes, but those of ordinary skill in the art should be understood that and can do various changes to it in the form and details, and without departing from the spirit and scope of the present invention.

Claims (10)

1. the data transmission method for uplink of a multiaerial system comprises M antenna that is used to launch in this system, and wherein M 〉=2 is characterized in that, may further comprise the steps:

Frequency domain data to be sent and pre-coding matrix multiplied each other generates the data of M road through precoding, and described M road is distinguished corresponding through the data of precoding with described M antenna;

For each antenna, will be to a road described data map through precoding that should the antenna part or all of subcarrier in N the subcarrier;

For each antenna, be that ((k's jCf D)+jE) multiplies each other for the plural phase sequence exp of N with the data on the described N subcarrier and length, wherein, C and E are real number, f (k, D) be a discontinuous function, k and D are f (k, D) variable of function, k is the numbering of subcarrier, 0≤k≤N-1, N are the subcarrier number on the whole system bandwidth, and D is the period of change or the step-length of this function, f after the value of D is determined (k, D) value of function is along with the variation of k every D a saltus step takes place;

For each antenna, the data on the described N subcarrier are carried out sending after the modulating in OFDM.

2. the data transmission method for uplink of multiaerial system according to claim 1 is characterized in that, described plural phase sequence exp (jCf (k D)+jE) is:

Or

Wherein, m is the sequence number of described antenna, d _mBe the virtual cycle delay on the described antenna, B is the subcarrier number of the feedback bandwidth correspondence of described pre-coding matrix, and k is the numbering and the 0≤k≤N-1 of subcarrier,

Expression rounds downwards and rounds up respectively, Be initial phase.

3. the data transmission method for uplink of multiaerial system according to claim 2 is characterized in that, described virtual cycle delay changes in time, and perhaps, described virtual cycle delay does not change in time.

4. the data transmission method for uplink of multiaerial system according to claim 2 is characterized in that, the pairing M of a described M antenna virtual cycle delay has two kinds of different values at least.

5. according to the data transmission method for uplink of each described multiaerial system in the claim 1 to 4, it is characterized in that, between the step of described OFDM modulation and the step of described emission, further comprising the steps of:

To adding Cyclic Prefix through the data of OFDM modulation.

6. a multiaerial system is characterized in that, comprising:

M the antenna that is used to launch, wherein M 〉=2;

Precoding unit, being used for frequency domain data to be sent and pre-coding matrix multiplied each other generates the data of M road through precoding, and every road is through the data of precoding one in the corresponding described M antenna respectively;

M map unit corresponds respectively to a described M antenna, and each map unit is respectively applied for described every road of described precoding unit output through the data map of the precoding part or all of subcarrier in N the subcarrier;

M multiplication unit, correspond respectively to a described M antenna, each multiplication unit is respectively applied for a described map unit is mapped to the plural phase sequence exp (jCf (k that data on the described N subcarrier and length are N, D)+jE) multiply each other, wherein, C and E are real number, (k D) is a discontinuous function to f, and k and D are f (k, D) variable of function, k is the numbering of subcarrier, and 0≤k≤N-1, D are the period of change or the step-length of this function, f after the value of D is determined (k, D) value of function is along with the variation of k every D a saltus step takes place;

M OFDM modulating unit corresponds respectively to a described M antenna, and each OFDM modulating unit is respectively applied for the data of a described multiplication unit output are carried out OFDM modulation back by corresponding antenna transmission.

7. multiaerial system according to claim 6 is characterized in that, described plural phase sequence exp (jCf (k D)+jE) is:

Or

Wherein, m is the sequence number of described antenna, d _mBe the virtual cycle delay on the described antenna, B is the subcarrier number of the feedback bandwidth correspondence of described pre-coding matrix, and k is the numbering of subcarrier, 0≤k≤N-1,

Expression rounds downwards and rounds up respectively,

Be initial phase.

8. multiaerial system according to claim 7 is characterized in that, described multiplication unit uses the virtual cycle delay that changes in time, and perhaps, described multiplication unit uses and do not change virtual cycle delay in time.

9. multiaerial system according to claim 7 is characterized in that, the pairing M of a described M antenna virtual cycle delay has two kinds of different values at least.

10. according to each described multiaerial system in the claim 6 to 9, it is characterized in that, also comprise:

M cyclic prefix CP unit corresponds respectively to M described antenna, and each cyclic prefix unit is respectively applied for adds Cyclic Prefix to the data of a described OFDM modulating unit output, and the data through adding Cyclic Prefix are passed through corresponding antenna emission.

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