CN1989722B - Time varying cyclic delay diversity of OFDM - Google Patents

Abstract

Methods and apparatuses that apply a time-varying delay to symbols to be transmitted from one or more antennas are provided.

Description

The time varying cyclic delay diversity of ofdm system

Cross reference

The application requires on May 17th, 2004 that submit, name to be called the provisional application No.60/572 of " Systems TimeVarying Cyclic Delay Diversity of OFDM " (ofdm system time varying cyclic delay diversity), 137 priority, this provisional application has transferred the application's assignee.

Technical field

This paper relates generally to radio communication, the particularly transmission of the signal in the multiaerial system.

Background technology

In wireless communication system, can be from the RF modulation signal of transmitter by a plurality of propagation paths arrival receivers.Owing to for example multiple factor of decline and multipath, the characteristic of propagation path changes usually in time.In order to provide diversity, can use a plurality of antennas that transmit and receive to suppress harmful path effects and to improve performance.Advance to have more (MIMO) communication system more and adopt a plurality of (N _TIndividual) transmitting antenna and a plurality of (N _RIndividual) reception antenna carries out transfer of data.By N _TIndividual transmitting antenna and N _RThe mimo channel that individual reception antenna constitutes can be decomposed into N _SIndividual independent channel, wherein N _S≤ min{N _T, N _R.N _SIn the individual independent channel each also can be called as a spatial sub-channel (perhaps transmission channel) of mimo channel, and corresponding to a dimension.

At least to a certain extent following situation is real, promptly, if the propagation path between transmitting antenna and the reception antenna be linearity independently (promptly, transmission on one paths can be as the linear combination of the transmission on other path and is formed), the possibility that then correctly receives transfer of data will increase along with the increase of antenna amount.Usually, when transmitting and receiving the antenna increase, diversity increases and performance improves.

In order further to improve the diversity of channel, can use transmit diversity techniques.Many transmit diversity techniques have been developed.Wherein a kind of technology is that emission postpones diversity.Postpone branch in emission and concentrate, transmitter utilizes two antennas to launch same signal, and wherein the signal of second antenna emission is the delay that first antenna transmits.Like this, second antenna usually forms diversity by setting up second group of independence multipath unit can collecting at the receiver place.If the multipath that first transmitter produces declines, then the multipath of second transmitter generation may not decline, and will keep acceptable signal-to-interference ratio (SNR) at the receiver place in this case.Because only need estimate compound TX0+TX1 channel at the receiver place, thereby this technology is easy to realize.The disadvantage that emission postpones diversity is its effective delay expansion that has increased channel, and when the multipath that second antenna causes begins to occur and takes place to interact devastatingly with the multipath of first antenna, the implementation effect of emission delay diversity is not good, has therefore reduced the integral level of diversity.

In order to handle standard delay diversity problem, developed other and postponed diversity technique.Wherein a kind of technology is called as cyclic delay diversity.Circulation delay is meant n _iThe sampling of each symbol is according to its order that is launched as the part of symbol displacement in the individual symbol.Those samplings that are positioned at outside the symbol live part are launched at the symbol section start.In this technology, prefix is added (pre-pend) postpone or each of order sampled from the front to having fixed, launch from specific antenna as the part of symbol so that will sample.Yet circulation delay can produce long delay, thereby it will be restricted to part protection gap periods to avoid intersymbol interference.

Cyclic delay diversity scheme may cause the frequency selectivity of channel, thereby it can provide the benefit of diversity for flat channel.Yet in the time of in channel is not selected in its time, cyclic delay diversity does not provide diversity any time.For example, if two transmitting antennas are in slow decline or the static channel cyclic shift Δ _mMay always make two channels (H for example ₁(n) and H ₂(n)) (perhaps structurally) stack (addition) devastatingly.

Therefore, expectation proposes a kind of delay diversity scheme, and it can will be used to provide the minimizing possibility of destructive or structural stack of the channel of diversity.

Summary of the invention

In a scheme, a kind ofly be used to provide the method for transmit diversity to comprise: behind first delay period, to provide first symbol to first antenna; Behind second delay period different, provide second symbol to first antenna with first delay period; Behind three delay period different with second delay period, provide the 3rd symbol to first antenna with first delay period.

In another program, a kind of transmitter comprises: at least two antennas; Modulator; And delay circuit, will output to delay period that changes in time of symbol delay of antenna from modulator.

In additional aspects, a kind of transmitting set comprises: at least two antennas; Memory, store a plurality of symbols, each symbol comprises a plurality of samplings, wherein, the a plurality of samplings that an antenna in described at least two antennas is exported first symbol after first postpones of described memory, and a plurality of samplings of after second postpones, exporting second symbol in described a plurality of symbol to a described antenna.Described first delay and described second postpones different.

In another program, a kind of transmitter comprises: at least three antennas; Modulator; First delay circuit is connected between the antenna in modulator and described two antennas at least, and it will output to the delay period that the symbol delay of antenna changes in time from modulator; And second delay circuit, being connected between another antenna in modulator and described at least two antennas, it will output to another delay period that the symbol delay of another antenna changes in time from modulator.Described another delay period is different with described delay period.

In another program, a kind of method of transmit diversity that provides in multichannel communication system comprises: first symbol that will launch on first antenna is used first phase shift; And second phase shift that described first symbol application that will launch is different from first phase shift on second antenna.

In another program, a kind of transmitter comprises: at least two antennas; Modulator; And phase-shift circuit, it uses the phase shift that changes in time to the symbol that is outputed to antenna by modulator.

Description of drawings

By the detailed description that provides below in conjunction with accompanying drawing, feature of the present invention, character and advantage will be more clear, and in the accompanying drawings, similar reference symbol correspondingly identifies, wherein:

Fig. 1 illustrates the block diagram of the embodiment of transmitter system and receiver system in the mimo system;

Fig. 2 illustrates the block diagram that the embodiment of the transmitter unit that postpones diversity is provided when providing;

Fig. 3 illustrates become the block diagram of the embodiment that postpones when applied from the symbol of same antenna emission;

Fig. 4 illustrates become the block diagram of the embodiment that postpones when applied from the symbol of a plurality of antennas emission;

Fig. 5 illustrates the block diagram that another embodiment of the transmitter unit that postpones diversity is provided when providing;

Fig. 6 illustrates the block diagram that becomes the embodiment of the receiver unit that postpones diversity in the time of can using;

Fig. 7 illustrates the block diagram of the embodiment of delay unit;

The flow chart of the embodiment of the method for variational set when being used to provide is provided Fig. 8;

Fig. 9 illustrates the block diagram that another embodiment of the transmitter unit that postpones diversity is provided when providing;

And

The flow chart of another embodiment of the method for variational set when being used to provide is provided Figure 10.

Embodiment

The detailed description that provides below in conjunction with accompanying drawing is intended to as the description to exemplary embodiment, and is not to be intended to representative can realize unique embodiment of the present invention.The term that uses in the specification " exemplary " refers to " as an example, example or example ", it should be considered as being preferable over or be better than other embodiment.Detailed description is included as the required detail of purpose that complete understanding of the present invention is provided.Yet, it will be apparent to one skilled in the art that the present invention can realize under the situation that does not possess these details.In some instances, with the form of block diagram known structure and equipment are shown, to avoid making notion of the present invention become unclear.

Multichannel communication system comprises advances to have more (MIMO) communication system, OFDM (OFDM) communication system, the mimo system (being the MIMO-OFDM system) that adopts OFDM and the transmission of other type more.For the sake of clarity, specifically describe various schemes and embodiment at mimo system.

Mimo system adopts a plurality of (N _TIndividual) transmitting antenna and a plurality of (N _RIndividual) reception antenna carries out transfer of data.By N _TIndividual transmitting antenna and N _RThe mimo channel that individual reception antenna constitutes can be decomposed into N _SIndividual independent channel, wherein N _S≤ min{N _T, N _R.N _SIn the individual independent channel each also can be called as a spatial sub-channel (perhaps transmission channel) of mimo channel.The quantity of spatial sub-channel is by the quantity decision of the eigen mode (eigenmode) of mimo channel, and the quantity of eigen mode depends on channel response matrix again H, wherein HN is described _TIndividual transmitting antenna and N _RResponse between the individual reception antenna.Channel response matrix HElement by independent Gaussian stochastic variable { h _{I, j}Form, i=1,2 ... N _R, j=1,2 ... N _T, h wherein _{I, j}It is the coupling (being complex gain) between j transmitting antenna and i the reception antenna.For simplicity, suppose channel response matrix HBe full order (be N _S=N _T≤ N _R), and an independent data stream can be from N _TIn the individual transmitting antenna each is launched.

Fig. 1 is the block diagram of the embodiment of transmitter system 110 and receiver system 150 in the mimo system 100.At transmitter system 110 places, provide the business datum of a plurality of data flow to emission (TX) data processor 114 from data source 112.In one embodiment, each data flow is launched on transmitting antenna separately.TX data processor 114 is based upon the specific coding scheme that is used to provide coded data that each data flow is selected, and the business datum of each data flow is formatd, encodes and interweaves.

Utilize for example Time Division Multiplexing or code division multiplexing (CDM), can the coded data and the pilot data of each data flow is multiplexing.The well known data type that pilot data is normally handled with known manner, and can be used for estimating channel response at the receiver system place.Then, be based upon the certain modulation schemes (for example BPSK, QPSK, M-PSK or M-QAM) that each data flow is selected, the multiplexed pilot and the coded data of each data flow are modulated (being sign map) so that modulation symbol to be provided.The data rate of each data flow, coding and modulation can be determined by the control that processor 130 provides.

Then, the modulation symbol with all data streams is provided to TX MIMO processor 120, the TX MIMO processor 120 further modulation symbols (for example OFDM) of handling.Then, TX MIMO processor 120 is with N _TIndividual stream of modulation symbols offers N _TIndividual transmitter (TMTR) 122a to 122t.Each transmitter 122 receives and handles symbols streams separately, so that one or more analog signal to be provided, and further analog signal is adjusted (for example amplification, filtering and up-conversion), so that the modulation signal that is adapted at transmitting on the mimo channel to be provided.

At receiver system 150 places, the modulation signal of being launched is by N _R Individual antenna 152a to 152r receives, and is provided to separately receiver (RCVR) 154 from the received signal of each antenna 152.Each receiver 154 is adjusted (for example filtering, amplification and down-conversion) received signal separately, with adjusted signal digitalized so that sampling to be provided, handles sampling then so that corresponding " reception " symbols streams to be provided.

Then, RX MIMO/ data processor 160 is from N _RIndividual receiver 154 receives N _RIndividual receiving symbol stream, and based on specific receiver treatment technology to N _RIndividual receiving symbol stream is handled, so that N to be provided _TIndividual " detection " symbols streams.Describe the processing that RX MIMO/ data processor 160 carries out below in detail.Each detected symbol stream comprises a plurality of symbols, and these symbols are the estimations to the modulation symbol of launching at respective stream of data.Then, RX MIMO/ data processor 160 carries out demodulation, deinterleaving and decoding to each detected symbol stream, to recover the business datum of this data flow.The processing that RX MIMO/ data processor 160 carries out is complementary mutually with the processing that the transmitter system 110 TX MIMO of place processors 120 and TX data processor 114 carry out.

RX MIMO processor 160 can be derived N for example based on the pilot tone multiplexing with business datum _TIndividual transmitting antenna and N _RThe estimation of the channel response between the individual reception antenna.Channel response is estimated to be used for to carry out space or sky/time at the receiver place and is handled.RX MIMO processor 160 can also be estimated the signal to interference and noise ratio (SNR) of detected symbol stream and other possible characteristic of channel, and this tittle is offered processor 170.RX MIMO/ data processor 160 or processor 170 can also be derived the estimation to " operation (operating) " SNR of system, the situation of its indication communication link.Then, processor 170 provides channel condition information (CSI), and it can comprise the various types of information about communication link and/or receiving data stream.For example, CSI can only comprise operation SNR.Then, CSI is handled by TX data processor 178, is modulated by modulator 180, and 154a to 154r adjusts by transmitter, and is sent back to transmitter system 110.

At transmitter system 110 places, receive by antenna 124 from the modulation signal of receiver system 150, adjust by receiver 122, by demodulator 140 demodulation, and handle, to recover CSI by the receiver system report by RX data processor 142.Then, the CSI that is reported is provided to processor 130, and is used for data rate and coding and modulation scheme that (1) is identified for data flow, and (2) generate the various controls to TX data processor 114 and TX MIMO processor 120.

Processor 130 and 170 is controlled at the operation at transmitter and receiver system place, and wherein transmitter and receiver links to each other with the suitable data processor that transmits and receives. Memory 132 and 172 is respectively processor 130 and 170 program code and the data of using provide storage.

The model of OFDM mimo system can be expressed as:

y= Hx+ n, equation (1)

Wherein, yBe to receive vector, promptly $\underset{\‾}{y}={\left[\begin{array}{cccc}{y}_1& y_2& ...& y_{N_R}\end{array}\right]}^T,$ { y wherein _iBe the item that receives from i reception antenna, i ∈ 1 ..., N _R;

xBe the emission vector, promptly $\underset{\‾}{x}={\left[\begin{array}{cccc}{x}_1& x_2& \·\·\·& x_{N_T}\end{array}\right]}^T,$ { x wherein _jBe the item of launching from j transmitting antenna, j ∈ 1 ..., N _T;

HIt is the channel response matrix of mimo channel;

nBe that mean vector is 0And covariance matrix Λ _n=σ ² IAdditive white Gaussian noise (AWGN), wherein 0By 0 vector of forming, IBe to be 1 and be 0 unit matrix on other position on the diagonal, σ ²It is noise variance; And

[.] ^TThe transposition of expression [.].

Because the scattering in the communication environments is from N _TThe N of individual transmission antennas transmit _TIndividual symbols streams interferes with each other at the receiver place.Especially, can be from a given symbols streams of a transmission antennas transmit by whole N _RIndividual reception antenna receives with different amplitudes and phase place.Thereby each received signal may comprise N _TThe component of each symbols streams in the individual emission symbols streams.N _RIndividual received signal will comprise whole N together _TIndividual emission symbols streams.Yet, described N _TIndividual symbols streams is dispersed in N _RAmong the individual received signal.

At the receiver place, can use various treatment technologies to handle N _RIndividual received signal is to detect N _TIndividual emission symbols streams.These receiver treatment technologies can be divided into two big classes:

Space and Space-Time receiver treatment technology (being also referred to as balancing technique), and

" zeroing/equilibrium and Interference Cancellation continuously " receiver treatment technology (being also referred to as " Interference Cancellation continuously " or " offsetting continuously " receiver treatment technology).

Fig. 2 is the block diagram of the part of transmitter unit 200, and it can be used as the embodiment of the transmitter section of transmitter system (for example transmitter system 110 among Fig. 1).In one embodiment, can be to will be at N _TThe N that launches on the individual transmitting antenna _TEach data flow in the individual data flow is used independent data rate and coding and modulation scheme (promptly carrying out independent coding and modulation based on each antenna).Can be identified for specific data rate and the coding and the modulation scheme of each transmitting antenna based on the control that processor 130 provides, and data rate can be determined according to mentioned above.

In one embodiment, transmitter unit 200 comprises transmit data processor 202, it receives, encodes and modulate each data flow according to independent coding and modulation scheme, modulation symbol to be provided and to launch, MIMO transmit data processor 202 and transmit data processor 204 are respectively transmit data processor 114 and an embodiment who launches MIMO processor 120 among Fig. 1.

In one embodiment, as shown in Figure 2, transmit data processor 202 comprises demodulation multiplexer 210, N _TIndividual encoder 212a to 212t and N _TIndividual channel interleaver 214a to 214t (promptly one group of demodulation multiplexer, encoder and channel interleaver being arranged) for each transmitting antenna.Demodulation multiplexer 210 is corresponding to N with data (being information bit) demultiplexing _TThe N of individual transmitting antenna _TIndividual data flow is to be used to carry out transfer of data.N _TIndividual data flow can be associated with different data rates, and it can be determined by the rate control feature that is provided by processor 130 or 170 (Fig. 1) in one embodiment.Each data flow is provided to encoder 212a to 212t separately.

Each encoder 212a to 212t receives data flow separately, and is based upon the specific coding scheme that described data flow selects described data flow is encoded, so that coded-bit to be provided.In one embodiment, coding can be used to increase reliability of data transmission.In one embodiment, encoding scheme can comprise the combination in any of Cyclic Redundancy Check coding, convolutional encoding, Turbo coding, block encoding etc.Then, will be provided to channel interleaver 214a to 214t separately from the coded-bit of each encoder 212a to 212t, channel interleaver 214a to 214t interweaves to coded-bit based on specific interleaving scheme.Interweave for coded-bit time diversity is provided, allow based on the transmission channel that is used for this data flow average SNR emission data, suppress decline and eliminate correlation between the coded-bit that is used to form each modulation symbol.

Be provided in the emission MIMO processor 204 separately sign map module 222a to 222t from the code interleaving bit of each channel interleaver 214a to 214t, sign map module 222a to 222t shines upon to form modulation symbol these bits.

Determined by the modulation control that processor 130 provides by the certain modulation schemes that each sign map module 222a to 222t realizes.Each sign map module 222a to 222t divides into groups a plurality of by q _jThe set that individual code interleaving bit constitutes to be to form non-binary symbols, then each non-binary symbols is mapped to the corresponding signal constellation which of selected modulation scheme (for example QPSK, M-PSK, M-QAM or other modulation scheme) in specified point.Each mapped signal point is corresponding to a M _jDimension (M _j-ary) modulation symbol, wherein M _jCorresponding to the certain modulation schemes that is j emitting antenna selecting, and $M_j=2^{q_j}.$ Then, sign map module 222a to 222t provides N _TIndividual stream of modulation symbols.

In the specific embodiment shown in Fig. 2, emission MIMO processor 204 also comprises modulator 224 and contrary fast fourier transform (IFFT) module 226a to 226t except comprising sign map module 222a to 222t.Modulator 224 modulation samplings are to form N on appropriate subband and transmitting antenna _TThe modulation symbol of individual stream.In addition, modulator 224 provides N with the power level of regulation _TEach symbols streams in the individual symbols streams.In one embodiment, modulator 224 can be according to the frequency hop sequences modulation symbol of being controlled by the processor of for example processor 130 or 170.In this embodiment, to N _TIndividual symbols streams is modulated the frequency that adopted and may be changed for the part of each group of transmission circulation or each piece symbol, each frame or frame.

The stream of modulation symbols that each IFFT module 226a to 226t receives separately from modulator 224.Each IFFT module 226a to 226t divides into groups a plurality of by N _FThe set that individual modulation symbol constitutes to be forming corresponding modulation symbol vector, and utilizes contrary fast fourier transform that each modulation symbol vector is converted to its time-domain representation (being called the OFDM symbol).IFFT module 226a to 226t can be designed to any amount (8,16,32 ..., N _F) frequency subchannels on carry out inverse transformation.

Each time-domain representation by the modulation symbol vector that IFFT module 226a to 226t generates is provided to relevant Cyclic Prefix generator 228a to 228t.Cyclic Prefix generator 228a to 228t adds the prefix with fixed qty sampling to constitute the OFDM symbol N from the front _SIndividual sampling is to form corresponding transmission symbol, a plurality of samplings that the sampling of described fixed qty is normally counted from OFDM symbol end.Prefix is designed to improve performance, with the harmful path effects such as channel diffusion that suppress for example to be caused by frequency selective fading.Then, Cyclic Prefix generator 228a to 228t is provided to relevant delay unit 230a to 230t-1 with transmitted symbol streams.

Each delay unit 230a to 230t-1 provides delay to each symbol from Cyclic Prefix generator 228a to 228t output.In one embodiment, the delay that provided of each delay unit 230a to 230t-1 changes in time.In one embodiment, this delay makes: it change between continuous symbol that Cyclic Prefix generator is exported or between the continuous symbol that will launch from transmitter unit 200 continuously.In another embodiment, delay may change between the group that is made of two, three, four or more symbols, and each symbol in one of them group has identical delay.In additional example, whole symbols in a frame or a Burst Period (burst period) have identical delay, wherein each symbol in each frame or the Burst Period all have with before or after frame or the different delay of each symbol in the Burst Period.

In addition, in the embodiment shown in Figure 2, all different with the delay that other delay cell provides by the delay that each delay unit 230a to 230t-1 provides.In addition, 228a is not connected to delay unit although Fig. 2 illustrates the Cyclic Prefix generator, yet other embodiment can be provided to delay unit each the output among the Cyclic Prefix generator 228a to 228t.

The symbol that delay unit 230a to 230t-1 is exported is provided to relevant transmitter 232a to 232t, makes antenna 232a to 232t launch described symbol according to the delay that delay unit 230a to 230t-1 is provided.

As mentioned above, in one embodiment, the time change that each delay unit 230a to 230t-1 is provided postpones Δ _mChange along with the time.In one embodiment, according to the delay of equation 2 i OFDM symbol launched from antenna m as the emission symbol:

$s\left((k-{\mathrm{\Δ}}_m)\mathrm{mod}N\right)=\frac{1}{\sqrt{N}}\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{X}_n{e}^{-j(2\mathrm{\π}/N)n{\mathrm{\Δ}}_m\left(i\right)}\·e^{-j(2\mathrm{\π}/N)\mathrm{nk}}$ (equation 2)

The whole channel table that obtains in this case can be shown

$H(i,n)=\underset{m=1}{\overset{M}{\mathrm{\Σ}}}{H}_m(i,n)e^{-j(2\mathrm{\π}/N)n{\mathrm{\Δ}}_m\left(i\right)}$ (equation 3)

H wherein _m(i is for channel n rank discrete Fourier transform (DFT) (DFT) coefficient from m transmitting antenna to the channel impulse response of reception antenna n).

Become when this by using and to postpone and frequency selectivity and time selectivity can be incorporated in the channel, it can be used to improve performance.For example, become when on different subcarriers and different OFDM symbol, transmission symbol being used and postpone, time selectivity and frequency selectivity can be provided simultaneously.In addition, under the situation that a plurality of users are transmitted, because the channel conditions of each receiver user is all different with the channel conditions of other receiver user, thereby the time of the channel that the delay by reindexing provides changes each user that can be used in a plurality of users provides diversity gain.

In one embodiment, postpone Δ _m(i) can postpone in the group with each continuous symbol or continuous symbol formation to change in time with linear mode under β situation of sampling of n*, wherein β is a constant, and n is 0,1, ..., change between the N-1, and wherein N is a symbol quantity in frame, Burst Period or the symbols streams.In another embodiment, postpone Δ _m(i) can be (to be N with respect to adjacent channel _TAntenna in the individual antenna) and before and/or afterwards symbol, based on the random delay of pseudo random sequence.In additional embodiment, postpone to change along with f (x), wherein f is a function, for example sinusoidal, cosine or other time-varying function, x is 0,1, ..., change between N-1 or its certain multiple, and wherein N is a symbol quantity in frame, Burst Period or the symbols streams.In each above-mentioned embodiment, postpone also can change based on feedback information, in this case, receiver is beamed back the CQI of describing whole channel conditions, and changes the delay Δ _m(i) to improve total quality.

With reference to figure 3, show become the embodiment that postpones when applied from the symbol of same antenna emission.Generate symbol S ₁, S ₂, S ₃And S ₄So that respectively at continuous slot T ₁, T ₂, T ₃And T ₄Launch during this time.Each symbol S ₁, S ₂, S ₃And S ₄Comprise nine sampling N _S1, N _S2, N _S3, N _S4, N _S5, N _S6, N _S7, N _S8, N _S9And two sampling Cyclic Prefix N _C1And N _C2, N wherein _C1And N _C2Be respectively sampling N _S8And N _S9The content that should be noted that each sampling may all be different for each symbol.Should be noted that sampling N _S1, N _S2, N _S3, N _S4, N _S5, N _S6, N _S7, N _S8, N _S9Can be according to N _S1, N _S2, N _S3, N _S4, N _S5, N _S6, N _S7, N _S8, N _S9Sequential combination form symbol S ₁

Then, delay unit (for example delay unit 230a) is to the symbol S from same antenna emission ₁, S ₂, S ₃And S ₄Delay is provided.In the embodiment shown in fig. 3, symbol S ₁Delay be a sampling period t ₁Will tighten at the same antenna and be connected on symbol S ₁Fa She next symbol S afterwards ₂Be delayed two sampling period t ₁And t ₂Will tighten at the same antenna and be connected on symbol S ₂Fa She next symbol S afterwards ₃Be delayed three sampling period t ₁, t ₂And t ₃Will tighten at the same antenna and be connected on symbol S ₃Fa She next symbol S afterwards ₄Be delayed four sampling period t ₁, t ₂, t ₃And t ₄If will launch diacritic on the same antenna, then next continuous symbol will be with five sampling period t ₁, t ₂, t ₃, t ₄And t ₅Delay launch.In this way, linear time-varying can be postponed to be applied to the transmission carried out from antenna, described antenna can be or can not be the part of mimo system.

The linear change that should be noted that delay period need not to be with a sampling period be the sequence of unit, and can be with 2 or more a plurality of sampling period be the sequence of unit, for example, the first symbol S ₁Can be delayed three sampling periods, the second symbol S ₂Can be delayed six sampling periods, the 3rd symbol S ₃Can be delayed nine sampling periods, the 4th symbol S ₄Can be delayed 12 sampling periods.In addition, linear change needn't change between each continuous symbol, but can change at symbols, for example, and symbol S ₁And S ₂Be delayed a sampling period respectively, symbol S ₃And S ₄Be delayed two or more a plurality of sampling period respectively.

With reference to figure 4, show when the symbol of a plurality of antenna emissions is used, becoming the embodiment that postpones.Will be from antenna A ₁, A ₂, A ₃And A ₄Last emission prosign S ₁Symbol S ₁Comprise nine sampling N _S1, N _S2, N _S3, N _S4, N _S5, N _S6, N _S7, N _S8, N _S9With two sampling Cyclic Prefix N _C1And N _C2, N wherein _C1And N _C2Be respectively sampling N _SAnd N _S9At the first antenna A ₁On not to symbol S ₁Use the delay in any sampling period.At the second antenna A ₂Go up symbol S ₁Postpone a sampling period t ₁At third antenna A ₃Go up symbol S ₁Postpone two sampling period t ₁And t ₂At the 4th antenna A ₄Go up symbol S ₁Postpone three sampling period t ₁, t ₂And t ₃Thus, in mimo system, except by antenna A ₁, A ₂, A ₃And A ₄Provide outside the space diversity, also can provide time and frequency diversity.

The time diversity that provides to scheme shown in Figure 4 and change the possibility that the identical sampling that can reduce prosign clashes, thus the minimizing possibility of destructive or structural stack of channel made.

Should be noted that to change to need not to be linear or relevant that if so long as will substantially side by side launch symbol, just the different amount of delay gets final product on each antenna with delay on other antenna in the delay between the prosign of launching on the same antenna.

Should be noted that employed progression needn't be corresponding to the quantity of antenna, and can group littler corresponding to ratio antenna quantity or bigger quantity change.

In addition, as discussion to Fig. 2, described delay can be at random and can be based on functions such as for example sinusoidal, cosine or other functions.In certain embodiments, delay period is restricted to a plurality of samplings in the symbol, and wherein delay period can carry out repetition after the symbol of fixing or random amount.In addition, should be noted that intersymbol delay can be the part sampling period, and be not restricted to the multiple in whole sampling period.The part clock cycle of one or more clock that in one embodiment, can be by using transmitter unit 200 realizes that part postpones.

With reference to figure 5, show the block diagram that another embodiment of the transmitter unit that postpones diversity is provided when providing.Transmitter unit 500 is basic identical with transmitter unit 200.In addition, scaling circuit (scaling circuit) 554a to 554t-1 is connected respectively to the output of one of delay unit 530a to 530t-1.The delay that each provided of scaling circuit 534a to 534t-1 in delay unit 534a to 534t-1 provides fixing calibration displacement (scalar shift).For example, each postpone is used fixing displacement, if make and for example use 0.5 constant displacement, then to postpone will be 0.5 sampling period a single sampling period, it will be a sampling period that two sampling periods postpone, and it will be 2.5 sampling periods that one five sampling period postpones.In one embodiment, each among the scaling circuit 554a to 554t-1 provides the displacement different with other scaling circuit.In one embodiment, provide linear progression on scaling circuit 554a to 534t-1, i.e. the displacement that provides of scaling circuit 554a is less than 554b, and the displacement that 554b provides is less than 554c or the like.

Although should be noted that Fig. 5 shows Cyclic Prefix generator 228a and is not connected to delay unit, other embodiment can be provided to delay unit each the output among the Cyclic Prefix generator 228a to 228t.In addition, 228a is not connected to scaling circuit although Fig. 5 shows the Cyclic Prefix generator, but other embodiment can be provided to scaling circuit each the output among the Cyclic Prefix generator 228a to 228t, and does not consider whether delay circuit is connected to the Cyclic Prefix generator.

With reference to figure 6, show the block diagram that becomes the embodiment of the receiver unit that postpones diversity in the time of to use.Transmitting is received by antenna 602a to 602r respectively, and is handled by receiver 604a to 604r, so that N to be provided _RIndividual sample streams, N _RIndividual sample streams will then be provided to RX processor 606.

In demodulator 608, Cyclic Prefix removes parts 612a to 612r and FFT module 614a to 614r provides N _RIndividual symbols streams.Cyclic Prefix removes parts 612a to 612r and removes the Cyclic Prefix that is included in each transmission symbol, so that corresponding recovery OFDM symbol to be provided.

Then, FFT module 614a to 614r utilizes fast fourier transform that each of symbols streams recovered symbol to carry out conversion, with provide by each transmission symbol in the cycle corresponding to N _FThe N of individual frequency subchannels _FThe vector that individual recovery modulation signal is formed.614a to 614r is with N for the FFT module _RIndividual receiving symbol stream is provided to spatial processor 620.

620 couples of N of spatial processor _RWhen flowing to row space or sky, handles individual receiving symbol, so that N to be provided _TIndividual detected symbol stream, N _TIndividual detected symbol stream is to N _TThe estimation of individual emission symbols streams.Spatial processor 620 can be realized linear ZF equalizer, channel correlation matrix counter-rotating (CCMI) equalizer, Minimum Mean Square Error (MMSE) equalizer, MMSE linear equalizer (MMSE-LE), DFF (DFE) or other equalizer, these are implemented in Application No. No.09/993,087,09/854,235,09/826,481 and 09/956, describe in 444 and illustrate, on the whole each above-mentioned application is included in herein by reference.

The time change that is provided by the delay unit of transmitter and/or scaling circuit can be provided spatial processor 620 postpones, and at Fig. 2 and Fig. 5 it is discussed.In one embodiment, for example, by make receiver 600 priori known become linear, become delay scheme at random or that become function based on pseudo random sequence, this compensation can be provided.For example, by making all transmitters use same scheme or providing, can provide above-mentioned cognition about information as the scheme of a communication initialization part between transmitter and the receiver unit 600.

Then, 622 pairs of detected symbol of multiplexer/demultiplexer are carried out multiplex/demultiplex, and will be corresponding to N _DThe N of individual data flow _DIndividual gathering detected symbol stream is provided to N _DIndividual symbol de-maps parts 624a to 624r.Then, each symbol de-maps parts 624a to 624r is according to coming detected symbol is carried out demodulation with the complementary mutually demodulation scheme of the modulation scheme that is used for data flow.Then, will be from N _DThe N of individual symbol de-maps parts 624a to 624r _DIndividual demodulated data stream is provided to RX data processor 610.

In RX data processor 610, channel deinterleaver 632a to 632r to be carrying out deinterleaving with the complementary mutually mode of the processing of data stream being carried out at the transmitter system place to each demodulated data stream, and decoder 634a to 634r is to decode to deinterleaved data with the complementary mutually mode of the processing of carrying out at the transmitter system place.For example, if carry out Turbo or convolutional encoding respectively at the transmitter unit place, then decoder 634a to 634r can adopt Turbo decoder or Viterbi decoder.Represent estimation from the decoded data stream of each decoder 634a to 634r to data streams.Decoder 634a to 634r also can provide each to receive status of packets (for example, correct reception or wrong the reception have been carried out in its indication).Decoder 634a to 634r can also store the demodulating data of the grouping that is not correctly decoded, and makes these data to merge with the data from the transmission of follow-up increase and to decode.

In the embodiment shown in fig. 6, channel estimator 640 is estimated channel response and noise variance, and these estimations are provided to processor 650.Can estimate channel response and noise variance based on the detected symbol of pilot tone.

Processor 650 can be designed to carry out the multiple function relevant with rate selection.For example, processor 650 can determine can be used for the maximum data rate of each data flow based on channel estimating and other parameter (for example modulation scheme).

With reference to figure 7, show the block diagram of the embodiment of delay unit.Processor 700 is connected with memory 704 via bus 702.Memory 704 is used for storing the sampling of the time-domain representation of the modulation symbol that is provided for transmission.The sampling of each symbol is stored in the known storage address of processor 700.Then, processor 700 can postpone by the time change of the symbol in continuous symbols or frame or the Burst Period being used any desired, the sampling of instruction memory 704 each symbol of output.

As the description at Fig. 3 and Fig. 4, the delay of each symbol may change between each symbol in the symbols that will launch continuously, and changes between different frames or the symbol in the Burst Period.The use of memory allows arbitrarily that predetermined or suitable scheme is used for providing delay to symbol, and therefore the time diversity that can change (for example linear change) based on channel conditions and predetermined scheme is provided.

With reference to figure 8, show the flow chart that the embodiment of the method that postpones diversity is provided when being used to provide.At square frame 800, provide the sampling that is illustrated in through the one or more modulation symbols after the contrary fast fourier transform.Then, at square frame 802, add Cyclic Prefix to each modulation symbol from the front.The size of prefix can change as required, and in one embodiment, prefix can be 32 or more a plurality of sampling.

Then, at square frame 804, will comprise that the sampling of Cyclic Prefix is stored in the memory, in one embodiment, memory can be a buffer.In one embodiment, according in the order that the sampling of each modulation symbol is provided after Cyclic Prefix is added in the front, described sampling is stored in the memory.In other embodiments, can be with the sampling of each modulation symbol of sequential storage of any desired.At square frame 806, postpone N according to first and remove first symbol that to launch.At square frame 808, remove the symbol that the next one will be launched according to second delay, wherein second delay and first postpones different.Second postpones and the additional delay of back symbol can be that N+ β postpones, and wherein β can increase or reduces, change at random takes place or as the result of certain function based on N from N is linear.

Then, at square frame 810, determine whether the symbol that needs to postpone is launched or uses.If be not defined as not, then at square frame 808, changing to the output from the back symbol of memory or buffer according to the identical time provides additional delay.If be defined as is that then processing finishes, and provides diacritic at square frame 812 according to the description to square frame 800-804.

With reference to Fig. 9, show the block diagram that another embodiment of the transmitter unit that postpones diversity is provided when providing.Transmitter unit 900 is basic identical with transmitter unit 200.Yet, replace to use the delay unit 230a to 230t-1 of the output that is connected to IFFT module 226a to 226t, phase-shift circuit 930a to 930t-1 is connected before the IFFT module 926a to 926t, to receive the output of modulator 924.Phase-shift circuit 930a to 930t-in a disguised form moves when the sampling of each symbol provides.For example, phase-shift circuit 930a can provide phase shift phi to the sampling of first symbol of modulator output ₁, provide phase shift phi to the sampling of the next one or back symbol ₁The sampling of back symbol can have the phase shift of identical or different amounts.After IFFT module 926a to 926t had carried out IFFT, this phase shift can be used as the delay in time domain.

Each phase-shift circuit 930a to 930t can provide the different phase shift with other phase-shift circuit 930a to 930t, so that make from the delay of the prosign of a plurality of antennas emission all inequality at each antenna.This variation can be or can not be the function that is applied in the phase shift on other antenna.

In one embodiment, the phase shift that provided of each phase-shift circuit 930a to 930t makes this phase shift change between the continuous symbol of modulator output.In other embodiments, phase shift can change between the group that is made of two, three, four or more a plurality of symbol, and wherein each symbol in the group has identical phase shift.In additional embodiment, all symbols in a frame or the Burst Period have identical phase shift, each frame or each Burst Period for each symbol have with before or after frame or the different phase shift of Burst Period.

Although should be noted that Fig. 9 shows phase-shift circuit and is not connected to Cyclic Prefix generator 928a, other embodiment can be provided to phase-shift circuit among the Cyclic Prefix generator 928a to 928t the output of each.

In certain embodiments, modulator and phase-shift circuit can comprise processor.

With reference to Figure 10, show the flow chart that the embodiment of the method that postpones diversity is provided when being used to provide.At square frame 1000, first phase shift phi is used in the sampling of first symbol of modulator output ₁Then, at square frame 1002, phase shift phi is used in the sampling of second symbol ₂, Φ wherein ₂With Φ ₁Different.Then, at square frame 1004, determine whether that symbol will be by phase shift in addition.If no, then square frame 106 then to the sampling of the next symbol of modulator output use may with Φ ₁Or Φ ₂Identical or different phase shifts.Repeat this processing then, till not having other symbol that phase shift will be used.

If there is not other symbol will carry out phase shift, then carry out IFFT at 1008 pairs of symbols of square frame, add Cyclic Prefix from the front at square frame 1010, and symbol is stored in the memory at square frame 1012, memory can be a buffer in one embodiment.In one embodiment, the order according to the sampling of each modulation symbol is provided after having added Cyclic Prefix from the front is stored in these samplings in the memory.In other embodiments, can be with the sampling of each modulation symbol of sequential storage of any desired.

In certain embodiments, phase shift may differ a phase place between continuous symbol, symbols or frame, this phase place equals one and decides angle (constant angle) and multiply by one corresponding to the variation numerical value of the position of symbol in symbols streams or other order numerical value.Should decide the angle can fix, perhaps can change with constant At All Other Times.In addition, for different antennas, the angle of deciding that is applied on the symbol can be different.

In other embodiments, phase shift can change according to the random phase with respect to other symbol.This can realize by using pseudo noise code to produce phase shift.

It should be noted that, although Figure 10 such as shows at pending IFFT and add Cyclic Prefix from the front, up to all symbols that phase shift are applied to a frame or Burst Period, but before the phase shift of finishing each symbol of a frame or Burst Period, can be individually or each symbol is carried out IFFT and add Cyclic Prefix from the front with the form of group.

It should be noted that, transmitter 200 and 500 can receive and handle separately stream of modulation symbols (for the MIMO that does not have OFDM) or transmitted symbol streams (for MIMO) with OFDM to generate modulation signal, modulation signal is then launched from relevant antenna.Also can realize other transmitter unit design, it will be positioned within the scope of the present invention.

Describe the coding and the modulation of the mimo system that has OFDM and do not have OFDM in the U.S. patent application below in detail:

U.S. number of patent application No.09/993,087, name is called " Multiple-AccessMultiple-Input Multiple-Output (MIMO) Communication System ", submits November 6 calendar year 2001;

U.S. number of patent application No.09/854,235, name is called " Method and Apparatusfor Processing Data in a Multiple-Input Multiple-Output (MIMO) Communication System Utilizing Channel State Information ", submits May 11 calendar year 2001;

U.S. number of patent application No.09/826,481 and 09/956,449, title is " Method and Apparatus for Utilizing Channel State Information in aWireless Communication System ", respectively at submitting on March 23 calendar year 2001 and September 18 calendar year 2001;

U.S. number of patent application No.09/776,075, name is called " Coding Scheme for aWireless Communication System ", submits February 1 calendar year 2001; And

U.S. number of patent application No.09/532,492, name is called " High Efficiency, HighPerformance Communications System Employing Multi-CarrierModulation ", submits on March 30th, 2000.

Above-mentioned application has all transferred the application's assignee, quotes these applications at this by reference.Application number No.09/776,075 has described a kind of encoding scheme, wherein can obtain different speed by utilizing identical basic code (for example convolution or Turbo code) that data are encoded, and the speed of punchinging and can obtain expecting by adjustment.Also can use other coding and modulation scheme, it will be positioned within the scope of the present invention.

It will be apparent to one skilled in the art that various schematic logic block, module, circuit and the algorithm described in conjunction with embodiment disclosed herein can be implemented as electronic hardware, computer software or both combinations.For this interchangeability of hardware and software clearly is described, aspect functional, various exemplary components, square frame, module, circuit and algorithm have been described prevailingly hereinbefore.Described function is embodied as hardware or is embodied as software and depends on application-specific and the designing requirement that is applied on the whole system.Those skilled in the art can the described function of accomplished in various ways for each application-specific, but these should not realized that the result is interpreted as having broken away from scope of the present invention.

Various schematic logic block, processor, module and the circuit of describing in conjunction with embodiment disclosed herein can be realized or carried out by following hardware, i.e. general processor, digital signal processor (DSP), circuit, application-specific integrated circuit (ASIC) (ASIC), field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components or be designed for the combination in any of carrying out function described herein.General processor can be a microprocessor, but alternatively, processor also can be any conventional processors, processor, microprocessor or state machine.Processor also can be realized with the combination of device, the combination of for example, the combination of the combination of DSP and microprocessor, a plurality of microprocessors, one or more microcontroller and the combination of DSP kernel, the combination of a plurality of logical blocks, a plurality of circuit or other such configuration.

In the software module or both combinations that method of describing in conjunction with embodiment disclosed herein or algorithm can be embodied directly in hardware, carried out by processor.Software module can reside in the storage medium of RAM memory, flash memory, ROM memory, eprom memory or any other form well known in the art.Exemplary storage medium is connected to processor, makes that processor can be from read information and to the storage medium writing information.Alternatively, storage medium can be integrated in the processor.Processor and storage medium can reside among the ASIC.ASIC can reside in the user terminal.Alternatively, processor and storage medium can be resident in user terminal be discrete assembly.

Provide the above-mentioned explanation of disclosed embodiment, so that make any technical staff of this area can both realize or use the present invention.The various modifications of these embodiment will be conspicuous to one skilled in the art, and under the situation that does not break away from the spirit or scope of the present invention, the General Principle of this paper definition can be applied to other embodiment.Therefore, the present invention is not subject to embodiment illustrated herein, and should give and principle disclosed herein and the corresponding to wide region of novel feature.

Claims (45)

1. method that transmit diversity is provided in multichannel communication system comprises:

First symbol that comprises first group of sampling is provided to first antenna;

Behind first delay period, provide described first symbol to second antenna;

Second symbol that comprises second group of sampling is provided to described first antenna;

Behind second delay period different, provide described second symbol to described second antenna with described first delay period;

The 3rd symbol that comprises the 3rd group of sampling is provided to described first antenna;

Behind three delay period different with described second delay period with described first delay period, provide described the 3rd symbol to described second antenna,

Wherein, each described symbol comprises the Cyclic Prefix with one or more samplings, wherein, described delay period changes according to defined time-varying function, wherein, the described delay period that changes according to defined time-varying function has boundary, wherein, does not select also can provide time diversity even channel does not have its time.

2. the method for claim 1, wherein described first symbol, second symbol and the 3rd symbol are the continuous symbols in the prosign stream.

3. the method for claim 1, wherein described the 3rd symbol is emission immediately behind described second symbol, and wherein said second symbol is emission immediately behind described first symbol.

4. the method for claim 1, wherein described first symbol, second symbol and the 3rd symbol are the discontinuous symbols in the prosign stream.

5. method as claimed in claim 4, wherein, described first symbol and a plurality of symbols of described second mark space, and described second symbol and the described a plurality of symbols of described the 3rd mark space.

6. the method for claim 1, wherein described first symbol, second symbol are launched in different frames respectively with the 3rd symbol.

7. the method for claim 1, wherein

Behind described first delay period, provide the step of described first symbol to comprise to each sampling application first phase shift in described first group of sampling;

Behind described second delay period different, provide the step of described second symbol to comprise to each sampling application second phase shift different in described second group of sampling with described first phase shift with described first delay period; And

Behind three delay period different with described second delay period, provide the step of described the 3rd symbol to comprise that the third phase different with described second phase shift with described first phase shift used in each sampling in described the 3rd group of sampling to be moved with described first delay period.

8. the method for claim 1, wherein, described first delay period comprises the delay in X sampling period, and described second delay period comprises the X+ β delay in a sampling period, and described the 3rd delay period comprises the X+2 β delay in a sampling period, and β is a constant.

9. the method for claim 1, wherein, described first delay period comprises the delay in X sampling period, described second delay period comprises the delay in Y sampling period, wherein Y sampling period is the sampling period that is different from any amount of X, and described the 3rd delay period comprises the delay in Z sampling period, and wherein Z sampling period is the sampling period that is different from any amount of X and Y.

10. the method for claim 1, wherein, described first delay period comprises the f delay in (x) individual sampling period, described second delay period comprises the f delay in (x+1) individual sampling period, and described the 3rd delay period comprises the f delay in (x+1) individual sampling period, wherein f is a function, and x is the numerical value that changes according to character position.

11. the method for claim 1 also comprises according to different carrier frequencies and modulates described first symbol, second symbol and the 3rd symbol.

12. the method for claim 1 also comprises described first delay period, second delay period and the 3rd delay period is used the calibration displacement.

13. a transmitter comprises:

At least two antennas;

Be connected to the modulator of described at least two antennas; And

Delay circuit, it is connected between in described modulator and described two antennas one at least, and described delay circuit utilization postpones the symbol that outputs to described antenna from described modulator according to the delay period that defined time-varying function changes,

Wherein, each described symbol comprises the Cyclic Prefix with one or more samplings, and wherein, the described delay period that changes according to defined time-varying function has boundary, wherein, does not select also can provide time diversity even channel does not have its time.

14. transmitter as claimed in claim 13, wherein, described delay circuit provides described delay period, makes described delay period different between a plurality of continuous symbols that outputed to described antenna by described modulator.

15. transmitter as claimed in claim 13, wherein, described delay circuit provides described delay period, makes described delay period differ a plurality of sampling periods between a plurality of continuous symbols, and described a plurality of sampling periods equal a constant and multiply by the variation numerical value corresponding to character position.

16. transmitter as claimed in claim 13, wherein, described delay circuit provides described delay period, makes described delay period differ the sampling period with respect to the random amount of other a plurality of continuous symbols between a plurality of continuous symbols.

17. transmitter as claimed in claim 13, wherein, described delay circuit provides described delay period, makes described delay period differ the individual sampling period of f (x) between a plurality of continuous symbols, and wherein f is a function, and x is the numerical value that changes according to character position.

18. transmitter as claimed in claim 13 also comprises scaling circuit, it is connected between described delay circuit and the described antenna.

19. transmitter as claimed in claim 13, wherein, described modulator uses a plurality of carrier frequencies to come modulation symbol.

20. transmitter as claimed in claim 13, wherein, described modulator and described delay circuit comprise processor.

21. transmitter as claimed in claim 13, wherein, described at least two antennas comprise at least three antennas, described transmitter also comprises another delay circuit, it is connected between another antenna in described modulator and described three antennas at least, described another delay circuit provides another delay period that changes in time, and wherein said another delay period is different with described delay period for each symbol.

22. transmitter as claimed in claim 21, wherein, described delay period is different between a plurality of continuous symbols that outputed to described antenna by described modulator, and described another delay period is different between a plurality of continuous symbols that outputed to described another antenna by described modulator, and wherein, described delay period between a plurality of continuous symbols changes β sampling of n*, and described another delay period between a plurality of continuous symbols changes n* (β+k) individual sampling, the position of n is-symbol in symbols streams wherein, β and k are constants.

23. transmitter as claimed in claim 13 also comprises the Cyclic Prefix generator circuit, it is connected between described modulator and the described delay circuit, and wherein said Cyclic Prefix generator circuit adds described Cyclic Prefix to each described symbol.

24. a transmitting set comprises:

At least two antennas; And

Be connected to the memory of described antenna, the a plurality of symbols of described memory stores, each symbol comprises a plurality of samplings, wherein, the a plurality of samplings that an antenna in described at least two antennas is exported first symbol in described a plurality of symbol after first delay period of described memory, and a plurality of samplings of exporting second symbol in described a plurality of symbol to a described antenna after second delay period, wherein said first delay period is different with described second delay period

Wherein, each described symbol comprises the Cyclic Prefix with one or more samplings, wherein, described delay period changes according to defined time-varying function, wherein, the described delay period that changes according to defined time-varying function has boundary, wherein, does not select also can provide time diversity even channel does not have its time.

25. transmitting set as claimed in claim 24, wherein, described second delay period is than the big n* β of described first delay period sampling, and wherein n is the ordinal position of described second symbol in symbols streams, and β is a constant.

26. transmitting set as claimed in claim 24, wherein, described first delay period is the individual sampling of f (x), and described second delay period is the individual sampling of f (x+1), and wherein f is a function, and x is the numerical value that changes according to character position.

27. transmitting set as claimed in claim 24, wherein, described memory comprises buffer.

28. transmitting set as claimed in claim 24, also comprise the Cyclic Prefix generator that is connected to described memory, before storing into described a plurality of symbols in the described memory, described Cyclic Prefix generator each symbol in described a plurality of symbols adds described Cyclic Prefix.

29. transmitting set as claimed in claim 24, wherein, described at least two antennas comprise at least three antennas, wherein, described memory provides described first symbol at another antenna in described at least three antennas behind the 3rd delay period, and provide described second symbol to described another antenna behind the 4th delay period, wherein said first delay period, second delay period, the 3rd delay period and the 4th delay period are all inequality each other.

30. transmitting set as claimed in claim 29, wherein, described second delay period and described first delay period differ n* β sampling, and described the 4th delay period and described the 3rd delay period differ n* (β+k) individual sampling, the position of n is-symbol in symbols streams wherein, β and k are constants.

31. a transmitter that is used to launch a plurality of symbols comprises:

A plurality of antennas;

Be connected to the modulator of described a plurality of antennas, it is modulated a plurality of symbols of launching on described a plurality of antennas; And

Be used for device that each symbol by the output of described modulator is provided delay period and change described delay period between a plurality of continuous symbols by described modulator output,

Wherein, each described symbol comprises the Cyclic Prefix with one or more samplings, wherein, described delay period changes according to defined time-varying function, wherein, the described delay period that changes according to defined time-varying function has boundary, wherein, does not select also can provide time diversity even channel does not have its time.

32. transmitter as claimed in claim 31, wherein, describedly be used to provide the device of delay period to comprise the device that is used between a plurality of continuous symbols, providing the delay period that changes with n* β sampling, the ordinal position of n is-symbol in symbols streams wherein, β is a constant.

33. transmitter as claimed in claim 31, wherein, the described device that is used to provide delay period comprises the device that is used for providing the delay period that the sampling period with random amount changes between a plurality of continuous symbols.

34. transmitter as claimed in claim 31, wherein, describedly be used to provide the device of delay period to comprise the device that is used for providing the delay period that changes with the individual sampling of f (x) between a plurality of continuous symbols, wherein f is a function, and x is the numerical value that changes according to character position.

35. transmitter as claimed in claim 31, wherein, described modulator uses a plurality of carrier frequencies that described a plurality of symbols are modulated.

36. transmitter as claimed in claim 31 also comprises the device that is used for using to the described delay period of each symbol that offers described a plurality of symbols the calibration displacement.

37. transmitter as claimed in claim 31 also comprises the device that is used for adding to each symbol of described a plurality of symbols the described Cyclic Prefix that is made of N sampling.

38. a transmitter comprises:

At least two antennas;

Be connected to the modulator of described at least two antennas;

First delay circuit, it is connected between the antenna in described modulator and described two antennas at least, and the delay period that the described first delay circuit utilization changes in time postpones the symbol that outputs to described antenna from described modulator;

Second delay circuit, it is connected between another antenna in described modulator and described two antennas at least, the described second delay circuit utilization postpones the symbol that outputs to described another antenna from described modulator according to another delay period that defined time-varying function changes

Wherein, described another delay period is different with described delay period, wherein, each described symbol comprises the Cyclic Prefix with one or more samplings, wherein, the described delay period that changes according to defined time-varying function has boundary, wherein, does not select also can provide time diversity even channel does not have its time.

39. transmitter as claimed in claim 38, wherein, described first delay circuit provides described delay period, make described delay period different between a plurality of continuous symbols that output to described antenna by described modulator, and described second delay circuit provides described another delay period, makes described another delay period different between a plurality of continuous symbols that outputed to described another antenna by described modulator.

40. transmitter as claimed in claim 38, wherein, described first delay circuit provides described delay period, makes described delay period differ a plurality of sampling periods between a plurality of continuous symbols, and described a plurality of sampling periods equal a constant and multiply by the variation numerical value corresponding to character position; And described second delay circuit provides described another delay period, make described another delay period differ a plurality of sampling periods between a plurality of continuous symbols, described a plurality of sampling periods equal another constant and multiply by the variation numerical value corresponding to character position.

41. transmitter as claimed in claim 38, wherein, described second delay circuit provides described another delay period, makes described another delay period differ the sampling period with respect to the random amount of other a plurality of continuous symbols between a plurality of continuous symbols.

42. transmitter as claimed in claim 38, wherein, described first delay circuit provides described delay period, make described delay period between a plurality of continuous symbols, differ the individual sampling period of f (x), wherein f is a function, x is the numerical value that changes according to character position, and described second delay circuit provides described another delay period, make described another delay period between a plurality of continuous symbols, differ the individual sampling period of g (x), wherein g is the function different with f, and x is the numerical value that changes according to character position.

43. transmitter as claimed in claim 38 also comprises: scaling circuit, it is connected between described first delay circuit and the described antenna; And another scaling circuit, it is connected between described second delay circuit and described another antenna.

44. transmitter as claimed in claim 38, wherein, described modulator uses a plurality of carrier frequencies to come modulation symbol.

45. transmitter as claimed in claim 38 also comprises: the Cyclic Prefix generator circuit, it is connected between modulator and described first delay circuit; And another Cyclic Prefix generator circuit, it is connected between described modulator and described second delay circuit.

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