CN1992690B - Emitting method of pilot data, base station controller, channel evaluation method and apparatus - Google Patents

Emitting method of pilot data, base station controller, channel evaluation method and apparatus Download PDF

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CN1992690B
CN1992690B CN200510121319A CN200510121319A CN1992690B CN 1992690 B CN1992690 B CN 1992690B CN 200510121319 A CN200510121319 A CN 200510121319A CN 200510121319 A CN200510121319 A CN 200510121319A CN 1992690 B CN1992690 B CN 1992690B
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domain channel
channel response
time domain
ofdm symbol
pilot
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CN1992690A (en
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党淑君
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Huawei Technologies Co Ltd
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Abstract

The invention provides a pilot data transmission method in the multi-transmission antenna orthogonal frequency-division multiplexing system, and it uses different transmission antennas to transmit pilot data on the same pilot model, the various transmission antennas having different symbols in pilot sub-carrier waves. Additionally, the invention also discloses a corresponding base station controller and the channel estimation method and device in the multi-transmission antenna orthogonal frequency-division multiplexing system. In the invention, since the different transmission antennas reuses pilot resources, even the number of transmission antenna increasing, the pilot sub-carrier wave density used by the system remains unchanged, thus enhancing the actual channel estimation performance in the orthogonal frequency division multiplexing system.

Description

Pilot data transmission method, base station controller, channel estimation methods and device
Technical field
The present invention relates to orthogonal multi-path frequency-division duplicating (OFDM) technology, relate to a kind of pilot data transmission method, base station controller, channel estimation methods and device in the multiple transmit antennas ofdm system or rather.
Background technology
The OFDM technology is as the frequency multiplexing technique with transmission of high-rate data service ability, and on the one hand, for traditional single-carrier technology, the OFDM technology can utilize simple equalization algorithm that higher spectrum efficiency is provided; On the other hand, in the system that adopts OFDM, do not need as traditional frequency division multiplex (FDM), between adjacent carrier wave, to distribute the protection bandwidth of broad, just can avoid the phase mutual interference between the subcarrier, thereby save bandwidth.
At present, the OFDM technology has been widely used in the existing communication system, and this technology has been embodied among WLAN standard 802.11a and the fixed wireless access standard 802.16a.In addition, in the mobile radio telecommunications connecting system, the wireless access network of third generation partner program (3GPP), the physical layer of IEEE 802.20 are also considering to use the OFDM technology, have the mobile radio telecommunications connecting system of higher frequency efficient with structure.
Figure 1 shows that the networking diagram of a typical frequency cellular re-use system.Wherein, two radio network controllers (RNC), be RNC1 and RNC2, (CN) links to each other with core net, and some base stations (BS) links to each other with these two RNC respectively, wherein, BS1, BS2 and BS3 link to each other with RNC1, and BS4, BS5 and BS6 link to each other with RNC2, two travelling carriages (MS), be MS1, MS2, keep wireless connections with these base stations.Fig. 2 is a typical sub-district omnidirectional antenna multiplex mode, abbreviates the cell reuse mode as, and Fig. 3 is typical sub-district 120 degree directional antenna multiplex modes, abbreviates the sector multiplex mode as.Adopted the data transmission system of OFDM technology to have the following advantages:
1) expansion has stronger fault-tolerance to multidiameter.As shown in Figure 4, comprise two parts on the OFDM symbol time domain: data division and Cyclic Prefix part, the Cyclic Prefix part is generated by the end circulation of data division, and the time that data division takies among the figure is T Data, the time that Cyclic Prefix partly takies is T CpThe fault-tolerance of OFDM technology shows: compare with the duration T s of an OFDM symbol, the duration of representative channel impulse response is very little, only takies very little part among the Ts, therefore can be by increasing less Cyclic Prefix, i.e. T CpTo overcome the interference between signals that causes by multipath fully.
2) frequency selective fading had stronger fault-tolerance.The OFDM technology can be recovered the entrained digital signal of deep fade subcarrier by redundancy schemes such as employing chnnel codings.
3) adopted simple equalization algorithm.Because the OFDM technology adopts frequency domain to transmit signal, and acting on of channel shows as simple multiplication on the frequency domain, thereby makes the data transmission system that adopts the OFDM technology when carrying out signal equalization, only needs a simple single tap equalizers to realize.
4) for the FDM technology, the OFDM technology has higher spectrum efficiency.
And multiple-input and multiple-output (MIMO) technology is a multi-antenna technology, promptly settles a plurality of antennas respectively at the transmitting terminal and the receiving terminal of communication system.It is exactly diversity and multiplexing that the key of MIMO technology is used: diversity mainly is to obtain space diversity gain by carrying out Space Time Coding at transmitting terminal; Multiplexing is to send the several separate data flow simultaneously to be used for improving transmission rate, and according to the basic theories of MIMO as can be known, minimum is relevant in the number that sends independent data stream and number of transmit antennas and the reception antenna number.
Combination based on above-mentioned two kinds of technology, is flat channel with the frequency selectivity multidiameter fading channel in the frequency domain internal conversion by OFDM, can reduce the influence of multipath fading. and in conjunction with multiple-input and multiple-output (MIMO, Multiple Input Multile Output) the abundant development space resource of technology, utilize a plurality of antennas to realize MIMO, not needing to increase under the situation of frequency spectrum resource and antenna transmission power, can improve the channel capacity and the availability of frequency spectrum exponentially.
But at present, the MIMO that industry proposes and OFDM in conjunction with the time relevant pilot design scheme in, frequency pilot sign that each transmitting antenna uses takies different time-frequency sub-carrier resources, as shown in Figure 5, wherein antenna 0 (main antenna) uses different subcarriers to transmit pilot data respectively with antenna 1, and the employed frequency pilot sign of each antenna is distinguished (quadrature) mutually.Accordingly, at a certain reception antenna end, receive pilot data, and then the pilot data that receives according to described each subcarrier carries out channel estimating from the corresponding subcarrier of each transmitting antenna.
The pilot tone of using owing to different transmitting antennas in the above-mentioned prior art takies different time-frequency sub-carrier resources, on the one hand, if the density of the pilot sub-carrier of fixed system (Overhead that is pilot tone keeps constant), along with the number of transmit antennas purpose increases, the employed pilot density of each antenna will reduce, thereby make pilot tone can not follow the tracks of the variation of channel, influence channel estimating performance, finally influence the efficient of system; On the other hand, along with the increase of number of antennas, if will guarantee the channel estimating performance (pilot density that is each antenna is constant) of each antenna, the pilot density of system will increase (corresponding pilot tone Overhead increases), also can influence the efficient of system.
In addition, in above-mentioned prior art scheme,, make pilot tone reduce, also can influence performance for estimating channel the follow-up control of channel delay expansion because pilot tone is too disperseed on frequency domain.
Summary of the invention
The technical problem that the present invention solves provides pilot data transmission method, base station controller and channel estimation methods and the device in the multiple transmit antennas ofdm system, to reduce the performance loss of recipient when carrying out channel estimating.
For addressing the above problem, pilot data transmission method in the multiple transmit antennas ofdm system of the present invention comprises:
Different transmit antennas is by identical pilot frequency mode emission pilot data, the emission symbol difference of each different transmit antennas on pilot sub-carrier.
Wherein, the relation of each different transmit antennas between the emission symbol on the pilot sub-carrier satisfies following formula:
D b ′ k , j = e i · 2 π ( τ b - τ b ′ ) · Δf · j D b k , j
Wherein, b, b ' are respectively b numbering that reaches the individual transmitting antenna of b ', b＜b ', D b K, j, D b' K, jBe respectively b j the frequency-region signal that subcarrier carried that reaches k pilot tone OFDM symbol of the individual transmission antennas transmit of b ', τ b, τ B 'Be respectively and b and the relevant time delay information of the individual transmitting antenna of b ', τ 1≤ τ b＜τ B ', τ 1Be the 1st the relevant time delay information of transmitting antenna, and τ B+1-τ bGreater than the time delay τ of channel, Δ f is the minimum frequency space between the subcarrier.
Preferably, the time delay spacing equalization of described each different transmit antennas.
Alternatively, described pilot frequency mode is that pilot tone OFDM symbol and OFDM data symbol are in regular distribution pattern, pilot tone OFDM symbol and OFDM data symbol on the time-domain irregular distribution pattern or pilot tone lattice point pattern on time-domain.
Correspondingly, a kind of multi-antenna orthogonal frequency division multiplexing system base station controller includes the base station control unit, and described base station control unit includes:
Many antennas emission controlling unit is used to control different transmitting antennas by identical pilot frequency mode emission pilot data, wherein the emission symbol difference of each different transmit antennas on pilot sub-carrier.
Wherein, the relation of each different transmit antennas between the emission symbol on the pilot sub-carrier satisfies following formula:
D b ′ k , j = e i · 2 π ( τ b - τ b ′ ) · Δf · j D b k , j
Wherein, b, b ' are respectively b numbering that reaches the individual transmitting antenna of b ', b＜b ', D b K, j, D b' K, jBe respectively b j the frequency-region signal that subcarrier carried that reaches k pilot tone OFDM symbol of the individual transmission antennas transmit of b ', τ b, τ B 'Be respectively and b and the relevant time delay information of the individual transmitting antenna of b ', τ 1≤ τ b＜τ B ', τ 1Be the 1st the relevant time delay information of transmitting antenna, and τ B+1-τ bGreater than the time delay τ of channel, Δ f is the minimum frequency space between the subcarrier.
Wherein, the time delay spacing equalization of described each different transmit antennas.
Wherein, described pilot frequency mode is that pilot tone OFDM symbol and OFDM data symbol are in regular distribution pattern, pilot tone OFDM symbol and OFDM data symbol on the time-domain irregular distribution pattern or pilot tone lattice point pattern on time-domain.
Correspondingly, channel estimation methods in the multiple transmit antennas ofdm system of the present invention comprises:
A. receive the mode pilot transmitted data of different transmit antennas by claim 1;
B. separate the pilot frequency information that receives, the frequency-region signal that obtains receiving on the pilot sub-carrier according to described pilot frequency mode;
C. according to being positioned at the frequency-region signal that receives on the pilot sub-carrier of same orthogonal multi-path frequency-division duplicating symbol, obtain the time domain channel response of different transmit antennas at this orthogonal multi-path frequency-division duplicating symbol place;
D. estimate the domain channel response at corresponding different transmit antennas data subcarrier place with the time domain channel response of the described different transmit antennas that obtains.
Wherein, described step c comprises:
C1. according to being positioned at the frequency-region signal that receives on the pilot sub-carrier of same OFDM symbol, obtain the time domain channel information at this OFDM symbol place;
C2. from the described time domain channel information that obtains, extract the time domain channel response of corresponding different transmit antennas.
Wherein, described step c1 may further comprise the steps:
C11. according to the frequency-region signal of described reception, and the domain data information on the pilot sub-carrier in the respective orthogonal frequency division multiplexing symbol of transmitting terminal emission, obtain the domain channel response at corresponding pilot sub-carrier place on the respective orthogonal frequency division multiplexing symbol;
C12. obtain the time domain channel information of respective orthogonal frequency division multiplexing symbol place pilot sub-carrier according to described domain channel response.
Wherein, each transmitting antenna of described step c2 obtains separately time domain channel response according to following method:
According to the time delay expansion that system supported, from the time domain channel reaction that obtains, determine the scope of blocking at b transmitting antenna;
The scope of blocking of obtaining b transmitting antenna corresponding time domain channel value in described time domain channel information replaces the time domain channel value that quilt is clipped in the described time domain channel reaction with 0, with the above-mentioned time domain channel sequence of the obtaining translation N that circulates forward bIndividual, obtain the time domain channel response of b transmitting antenna, wherein N bBe b transmitting antenna channel delay corresponding sampling points number.
Wherein, each transmitting antenna of described step c2 obtains separately time domain channel response according to following method:
The scope of blocking of b transmitting antenna is determined in the time domain channel reaction at the OFDM symbol place by analyzing continuous time;
Obtain this and block scope corresponding time domain channel value in described time domain channel information, and with 0 replace described time domain channel react in not selected time domain channel value, with the above-mentioned time domain channel sequence of the obtaining translation N that circulates forward bIndividual, obtain the time domain channel response of b transmitting antenna, wherein N bBe b transmitting antenna channel delay corresponding sampling points number.
Alternatively, described steps d may further comprise the steps:
D11. estimate by the time domain channel response at the OFDM symbol place that comprises pilot sub-carrier of different transmit antennas that obtains is carried out interpolation, obtain at the adjacent of respective transmit antenna and comprise the time domain channel response at the OFDM symbol place of data with the described OFDM symbol that comprises pilot sub-carrier;
D12. the above-mentioned time domain channel response at the OFDM symbol place that comprises data of respective transmit antenna that obtains is carried out inverse fourier transform, obtain corresponding domain channel response at described respective transmit antenna.
Alternatively, described steps d may further comprise the steps:
D21. obtain corresponding domain channel response according to time domain channel response at respective transmit antenna at the OFDM symbol place that comprises pilot sub-carrier of a certain transmitting antenna;
D22. according to the domain channel response at the OFDM symbol place that comprises pilot sub-carrier of respective transmit antenna of gained, estimate at the adjacent of respective transmit antenna and comprise the domain channel response at the OFDM symbol place of data with the described OFDM symbol that comprises pilot sub-carrier.
Alternatively, described steps d 22 is: directly with the domain channel response at the OFDM symbol place that comprises pilot sub-carrier of gained as adjacent with described OFDM symbol and comprise the domain channel response at the OFDM symbol place of data.
Alternatively, described steps d 22 is: the domain channel response to the OFDM symbol place that comprises pilot sub-carrier of gained is revised, and with revised domain channel response as adjacent with described OFDM symbol and comprise the domain channel response at the OFDM symbol place of data.
Alternatively, described steps d 22 is: the domain channel response at the OFDM symbol place that comprises pilot sub-carrier is carried out interpolation estimate, obtain adjacent with described OFDM symbol and comprise the domain channel response at the OFDM symbol place of data.
Alternatively, described interpolation is estimated to adopt 2 l-1 lagrange-interpolation or 1 Lagrange's interpolation algorithm.
Correspondingly, channel estimating apparatus in a kind of multiple transmit antennas ofdm system comprises:
Receiving system is used to receive the mode pilot transmitted data of different transmit antennas by claim 1;
The pilot frequency information separator is used for separating the pilot frequency information that receives, the frequency-region signal that obtains receiving on the pilot sub-carrier according to described pilot frequency mode;
The time domain channel response deriving means according to the frequency-region signal that receives on the pilot sub-carrier that is positioned at same orthogonal multi-path frequency-division duplicating symbol, obtains the time domain channel response of different transmit antennas at this orthogonal multi-path frequency-division duplicating symbol place;
The domain channel response deriving means is estimated the domain channel response at corresponding different transmit antennas data subcarrier place with the time domain channel response of the described different transmit antennas that obtains.
Wherein, described time domain channel response deriving means comprises:
The time domain channel information acquisition unit according to the frequency-region signal that receives on the pilot sub-carrier that is positioned at same OFDM symbol, is obtained the time domain channel information at this OFDM symbol place;
The time domain channel response extraction unit, the time domain channel response of the corresponding different transmit antennas of extraction from the described time domain channel information that obtains.
Wherein, described time domain channel information acquisition unit comprises:
First obtains subelement, frequency-region signal according to described reception, and the domain data information on the pilot sub-carrier in the respective orthogonal frequency division multiplexing symbol of transmitting terminal emission, obtain the domain channel response at corresponding pilot sub-carrier place on the respective orthogonal frequency division multiplexing symbol;
Second obtains subelement, obtains the time domain channel information of respective orthogonal frequency division multiplexing symbol place pilot sub-carrier according to described domain channel response.
Alternatively, described time domain channel response extraction unit comprises:
First determines subelement, according to the time delay expansion that system supported, determines the scope of blocking at b transmitting antenna from the time domain channel reaction that obtains;
First time domain channel response extracts subelement, obtain the time domain channel value of the scope of blocking correspondence in described time domain channel information of b transmitting antenna, replace the time domain channel value clipped in the described time domain channel reaction with 0, with the above-mentioned time domain channel sequence of the obtaining translation N that circulates forward bIndividual, obtain the time domain channel response of b transmitting antenna, wherein N bBe b transmitting antenna channel delay corresponding sampling points number.
Alternatively, described time domain channel response extraction unit comprises:
Second determines subelement, and the scope of blocking of b transmitting antenna is determined in the time domain channel reaction at the OFDM symbol place by analyzing continuous time;
Second time domain channel response extracts subelement, obtain the time domain channel value that this blocks scope correspondence in described time domain channel information, and replace not selected time domain channel value in the described time domain channel reaction with 0, with the above-mentioned time domain channel sequence of the obtaining translation N that circulates forward bIndividual, obtain the time domain channel response of b transmitting antenna, wherein N bBe b transmitting antenna channel delay corresponding sampling points number.
Alternatively, described domain channel response deriving means comprises:
The interpolation estimation unit, estimate by the time domain channel response at the OFDM symbol place that comprises pilot sub-carrier of different transmit antennas that obtains is carried out interpolation, obtain at the adjacent of respective transmit antenna and comprise the time domain channel response at the OFDM symbol place of data with the described OFDM symbol that comprises pilot sub-carrier;
The first domain channel response acquiring unit, the above-mentioned time domain channel response at the OFDM symbol place that comprises data of respective transmit antenna that obtains is carried out inverse fourier transform, obtain corresponding domain channel response at described respective transmit antenna.
Alternatively, described domain channel response deriving means comprises:
The second domain channel response acquiring unit obtains corresponding domain channel response at respective transmit antenna according to the time domain channel response at the OFDM symbol place that comprises pilot sub-carrier of a certain transmitting antenna;
The 3rd domain channel response acquiring unit, according to the domain channel response at the OFDM symbol place that comprises pilot sub-carrier of respective transmit antenna of gained, estimate at the adjacent of respective transmit antenna and comprise the domain channel response at the OFDM symbol place of data with the described OFDM symbol that comprises pilot sub-carrier.
Alternatively, described the 3rd domain channel response acquiring unit obtains domain channel response and is: directly with the domain channel response at the OFDM symbol place that comprises pilot sub-carrier of gained as adjacent with described OFDM symbol and comprise the domain channel response at the OFDM symbol place of data.
Alternatively, described the 3rd domain channel response acquiring unit obtains domain channel response and is: the domain channel response to the OFDM symbol place that comprises pilot sub-carrier of gained is revised, and with revised domain channel response as adjacent with described OFDM symbol and comprise the domain channel response at the OFDM symbol place of data.
Alternatively, described the 3rd domain channel response acquiring unit obtains domain channel response and is: the domain channel response at the OFDM symbol place that comprises pilot sub-carrier is carried out interpolation estimate, obtain adjacent with described OFDM symbol and comprise the domain channel response at the OFDM symbol place of data.
Wherein, described interpolation is estimated to adopt 2 l-1 lagrange-interpolation or 1 Lagrange's interpolation algorithm.
Compared with prior art, the present invention has following beneficial effect:
Different transmit antennas is by identical pilot frequency mode emission pilot data among the present invention, and when carrying out channel estimating, receiving terminal at first receives different transmit antennas by identical pilot frequency mode pilot transmitted data; Separate the pilot frequency information that receives, the frequency-region signal that obtains receiving on the pilot sub-carrier according to described pilot frequency mode then; According to being positioned at the frequency-region signal that receives on the pilot sub-carrier of same orthogonal multi-path frequency-division duplicating symbol, obtain the time domain channel response of different transmit antennas again at this orthogonal multi-path frequency-division duplicating symbol place; Estimate the domain channel response at subcarrier place, corresponding different transmit antennas data place at last with the time domain channel response of the described different transmit antennas that obtains.Because it (is that each transmitting antenna uses identical pilot sub-carrier that different transmit antennas is reused pilot resources, just each transmitting antenna is launched the symbol difference on corresponding pilot sub-carrier), different emission symbols has guaranteed that the channel estimating performance between each antenna is unaffected between each transmitting antenna, even number of transmit antennas increases, the employed pilot sub-carrier density of system also remains unchanged, thereby can improve actual channel estimation performance in the ofdm system, improve the data transmission efficiency of real system; Can effectively improve the performance of delayedchannel especially, increase the applicability of data communication system channel circumstance.On the other hand, in many antenna emission situations, different transmitting antennas uses identical pilot frequency mode, also can not increase the overhead of pilot tone among the present invention.
Description of drawings
Fig. 1 is the networking diagram of a kind of typical frequency cellular re-use system in the prior art;
Fig. 2 is a kind of typical sub-district omnidirectional antenna multiplex mode schematic diagram in the prior art;
Fig. 3 is a kind of typical sub-district 120 degree directional antenna multiplex mode schematic diagrames in the prior art;
Fig. 4 is an OFDM schematic symbol diagram in the prior art;
Fig. 5 is a kind of pilot design scheme of prior art schematic diagram;
Fig. 6 is the schematic diagram of transmitting terminal emission OFDM symbol among the present invention;
Fig. 7 is the schematic diagram that receiving terminal receives the OFDM symbol among the present invention;
Fig. 8 is the schematic diagram of channel estimation methods in the multiple transmit antennas of the present invention;
Fig. 9 is a kind of pilot tone OFDM symbol and OFDM data symbol regular distribution pattern diagram on time-domain in the first embodiment of the invention;
Figure 10 is a pilot tone OFDM symbolic construction schematic diagram;
Figure 11 is the OFDM data symbol structural representation;
Figure 12 is the numbering segment schematic diagram of OFDM symbol among the present invention program;
Figure 13 is the main flow chart of a kind of channel estimation methods of first embodiment of the invention;
Figure 14 is the main flow chart of the another kind of channel estimation methods of first embodiment of the invention;
Figure 15 is pilot tone OFDM symbol and OFDM data symbol irregular distribution pattern schematic diagram on time-domain in the second embodiment of the invention;
Figure 16 is the main flow chart of a kind of channel estimation methods in the second embodiment of the invention;
Figure 17 is the schematic diagram of pilot tone lattice point pattern in the third embodiment of the invention;
Figure 18 is the main flow chart of a kind of channel estimation methods in the third embodiment of the invention;
Figure 19 is the main flow chart of another kind of channel estimation methods in the third embodiment of the invention;
Figure 20 is the schematic block diagram of channel estimating apparatus of the present invention;
Figure 21 is the composition frame chart of time domain channel response deriving means of the present invention;
Figure 22 is a kind of composition frame chart of domain channel response deriving means of the present invention;
Figure 23 is the another kind of composition frame chart of domain channel response deriving means of the present invention;
Figure 24 is 32 o'clock for blocking the footpath number, under Vehicle A channel, the 30kmph situation, and the channel estimating performance emulation schematic diagram that adopts the present invention program to obtain;
Figure 25 is 32 o'clock for blocking the footpath number, under Vehicle A channel, the 60kmph situation, and the channel estimating performance emulation schematic diagram that adopts the present invention program to obtain;
Figure 26 is 160 o'clock for blocking the footpath number, under Vehicle B channel, the 30kmph situation, and the channel estimating performance emulation schematic diagram that adopts the present invention program to obtain.
Embodiment
Core of the present invention is different transmit antennas by identical pilot frequency mode emission pilot data, and described pilot frequency mode can adopt pilot tone OFDM symbol and OFDM data symbol in regular distribution pattern on the time-domain or pilot tone OFDM symbol and OFDM data symbol irregular distribution pattern or pilot tone lattice point pattern on time-domain.In addition, adopt in the emission symbol difference of each different transmit antennas on pilot sub-carrier among the present invention.
Based on above-mentioned pilot data transmission pattern, receiving terminal is when carrying out channel estimating, by receiving different transmit antennas by identical pilot frequency mode pilot transmitted data among the present invention; Separate the pilot frequency information that receives, the frequency-region signal that obtains receiving on the pilot sub-carrier according to described pilot frequency mode then; According to the frequency-region signal that receives on the pilot sub-carrier that is positioned at same orthogonal multi-path frequency-division duplicating symbol, obtain the time domain channel response of different transmit antennas at this orthogonal multi-path frequency-division duplicating symbol place; Estimate the domain channel response at subcarrier place, corresponding different transmit antennas data place with the time domain channel response of the described different transmit antennas that obtains.
Be described in detail below.
At first the process of transmitting terminal emission OFDM symbol is made brief description.Process with antenna b emission data is an example, transmitting terminal is the multiplex mode on time-frequency plane according to antenna b pilot transmitted OFDM symbol and OFDM data symbol at first, carry out multiplexing to pilot tone OFDM symbol and OFDM data symbol, the frequency-region signal that generation is used to launch, afterwards, this frequency-region signal is further carried out processes such as inverse fourier transform, digital-to-analogue conversion, and the electromagnetic signal that will finally generate launches, this processing procedure as shown in Figure 6.
Control by base station controller (BSC) at above-mentioned transmitting terminal emission pilot data among the present invention, during specific implementation, described base station controller includes the base station control unit, and wherein said base station control unit includes:
Many antennas emission controlling unit is used to control different transmitting antennas by identical pilot frequency mode emission pilot data, wherein the emission symbol difference of each different transmit antennas on pilot sub-carrier.
Corresponding with transmitting terminal, the structural representation that realizes a receiving terminal of the present invention as shown in Figure 7.When receiving data, at first the electromagnetic signal that receives from channel is carried out data sampling, according to the synchronizing information of having obtained, the sampled data that receives is carried out OFDM symbol extraction, FFT conversion, demultiplexing on time domain, form the pilot tone OFDM symbol and the OFDM data symbol that receive; After this utilize the pilot tone OFDM symbol receive and at corresponding time-frequency position pilot transmitted OFDM symbol, use certain channel estimation method, obtain on the time-frequency plane carrying data the time frequency place domain channel response, received signal value in conjunction with the corresponding data symbol, carry out operations such as channel equalization, further recover the data-signal of emission.
With reference to figure 8, this figure is the schematic diagram of channel estimation methods in the multiple transmit antennas of the present invention.
As shown, at first utilize the frequency pilot sign of pilot transmitted data and reception in the given OFDM symbol to estimate the domain channel response value at corresponding OFDM symbol place among the present invention, through string and conversion and IFFT, further obtain the time domain channel response value at corresponding OFDM symbol place, by analysis to the time domain channel response value that obtained, extract time domain channel information (information that comprises footpath and attenuation thereof) at different transmit antennas, utilize certain time domain channel algorithm for estimating (specific interpolation algorithm), further estimate time domain channel response at the OFDM symbol place that comprises data symbol of different transmit antennas, at last, through FFT and also string conversion, obtain domain channel response value, utilize the domain channel response value of gained can carry out other operations such as channel equalization then at the OFDM symbol place that comprises data symbol of different transmit antennas.
Describe with specific embodiment below.
First embodiment
The pilot tone OFDM symbol in the present embodiment on the time-domain of a kind of rule of employing and the distribution of OFDM data symbol are as the pilot frequency distribution pattern, each transmitting antenna adopts identical pilot frequency distribution pattern, a specific embodiment of this pattern comprises n OFDM data symbol between adjacent two pilot tone OFDM symbols among the figure as shown in Figure 9.
Wherein pilot tone OFDM symbol can be identical with OFDM data symbol length, also can the length difference; The same with common OFDM symbol, pilot tone OFDM symbol and OFDM data symbol also are partly to be made of data division and Cyclic Prefix, and the Cyclic Prefix part is generated by the end circulation of data division.
Concrete, the structure of pilot tone OFDM symbol as shown in figure 10: the number of the sampled point that the Cyclic Prefix of OFDM data symbol partly takies is N P, cp, the number of the sampled point that data division takies is N P, data
The structure of OFDM data symbol as shown in figure 11, the number of the sampled point that the Cyclic Prefix of OFDM data symbol partly takies is N D, cp, the number of the sampled point that data division takies is N D.data
The above embodiment of the present invention for convenience of description, the transmitting terminal OFDM symbols transmitted is numbered according to coding rule described below:
● the numbering of pilot tone OFDM symbol: pilot tone OFDM symbol is numbered in turn according to the time sequencing of emission, and the numbering of emission is less earlier;
● the numbering naturally of the OFDM data symbol between the adjacent pilot frequencies OFDM symbol: from 0 to n-1 serial number, the numbering of emission is less earlier;
● the numbering of OFDM data symbol: the combination number that is applicable to above-mentioned two numberings.
The one section OFDM symbol number segment that is suitable for above-mentioned coding rule is illustrated in fig. 12 shown below, and dash area is a pilot tone OFDM symbol among the figure, and numeral is the numbering of corresponding OFDM symbol.
Further, suppose total B transmitting antenna, j the frequency-region signal that subcarrier carried of k pilot tone OFDM symbol of b transmission antennas transmit is D b K, j, satisfy:
D b ′ k , j = e i · 2 π ( τ b - τ b ′ ) · Δf · j D b k , j
D 1 k，j＝D k，j
Wherein, b, b ' are respectively b numbering that reaches the individual transmitting antenna of b ', b＜b ', D b K, j, D b' K, jBe respectively b j the frequency-region signal that subcarrier carried that reaches k pilot tone OFDM symbol of the individual transmission antennas transmit of b ', τ b, τ B 'Be respectively and b and the relevant time delay information of the individual transmitting antenna of b ', τ 1≤ τ b＜τ B ', and τ B+1-τ bGreater than the time delay τ of channel, Δ f is the minimum frequency space between the subcarrier.
During specific implementation, the time delay spacing equalization of described each different transmit antennas can be set also among the present invention, τ promptly is set B+1-τ b=τ B+1-τ B '
According to the distribution pattern of above-mentioned pilot tone OFDM symbol in time domain, and the correlation of frequency pilot sign between the different transmit antennas. the receiver corresponding with a certain reception antenna (comprises Frequency Synchronization synchronously obtaining in the present embodiment, sign synchronization, frame synchronization) after, in the time-domain signal that receives, separate pilot tone OFDM symbol and OFDM data symbol, and according to the pilot tone OFDM symbol that extracts, the domain channel response of data estimator OFDM symbol, further OFDM data symbol is carried out other operations such as channel equalization, to recover the data of emission, with reference to Figure 13, a kind of concrete channel estimation process comprises following step in the present embodiment:
Step 11 is obtained the time domain channel information of pilot tone OFDM symbol from the time domain pilot OFDM symbol that receives;
The time-domain signal sequence of reception of supposing k pilot tone OFDM symbol of a certain reception antenna is Through after the FFT, the frequency domain received signal sequence that obtains is Thereby the domain channel response of k pilot tone OFDM symbol place channel is
Figure G2005101213190D00153
Brief note is
Figure G2005101213190D00154
As previously described, Be k the frequency domain data sequence that pilot tone OFDM symbol is carried.Further, resulting domain channel response
Figure G2005101213190D00156
Process IFFT obtains the time domain channel information of k pilot tone OFDM symbol place channel later on, notes by abridging to be
Figure G2005101213190D00157
Step 12 is from the time domain channel response of the corresponding different transmit antennas of the time domain channel information extraction of pilot tone OFDM symbol channel at corresponding pilot tone OFDM symbol place, the attenuation in for example Jing delay, footpath;
After the time domain channel response that obtains pilot tone OFDM symbol place, need utilize these information that channel is analyzed, to obtain efficient channel information, reduce the noise of channel at different transmit antennas.
A kind of extracting method of simple channel information is the simple truncation method, under the situation of the channel delay span of known wireless transmission environment, can make in this way among the present invention, for certain antenna, b transmitting antenna for example, at first according to the expansion of time delay that system supported, from the time domain channel reaction that obtains, determine the scope of blocking at definite b the transmitting antenna of time domain channel reaction of the scope of blocking of b transmitting antenna or the OFDM symbol by analyzing continuous time; The scope of blocking of obtaining b transmitting antenna then corresponding time domain channel value in described time domain channel information replaces the time domain channel value that quilt is clipped in the described time domain channel reaction with 0, with the above-mentioned time domain channel sequence of the obtaining translation N that circulates forward bIndividual, thus the time domain channel response of b transmitting antenna obtained, N wherein bBe b transmitting antenna channel delay corresponding sampling points number.
The delay of hypothesis channel mostly is N sampled point most in the said method, and can be directly react the time domain channel of the pilot tone OFDM symbol place channel that obtains this moment Block, the scope of blocking is slightly larger than the number of the maximum delay corresponding sampling points of channel, and for example blocking length is N ', satisfies N ' 〉=N, obtains this moment at the time domain channel response at k pilot tone OFDM symbol place of b transmitting antenna being Wherein 0 number is N P, data-N '.
Step 13 is utilized the time domain channel response at the adjacent pilot frequencies OFDM symbol place of a certain transmitting antenna, utilizes specific interpolation method to estimate time domain channel response at the OFDM data symbol place of this transmitting antenna;
At the time domain channel response that has obtained at k pilot tone OFDM symbol place of b transmitting antenna be (, it is designated as (c in order to write conveniently K, 0 p, c K, 1 p..., c K, N ' p, 0 ..., 0)) after, further just can estimate time domain channel information (c at the OFDM data symbol place channel of b transmitting antenna S, 0 d, c S, 1 d..., c S, N ' d, 0 ..., 0), s is the numbering of OFDM data symbol in the formula.
Can utilize (..., c K-1, h p, c K, h p, c K+1, h p, c K+2, h p...) estimate c (k, j), h dValue, in the formula j be described OFDM data symbol with pilot tone OFDM symbol that described OFDM data symbol is faced mutually between numbering naturally.
Estimate c (k, j), h dValue can adopt the Lagrange interpolation 2l-1 time, typical estimation formulas is as follows:
c ( k , j ) , h d = Σ m = - l + 1 l c k + m , h p · ( 1 ( Π q = 1 l - n q ) · ( Π q = - l + 1 - m - 1 q ) ) · ( Π q = - l + 1 l ( j + 1 n + 1 - q ) ( j + 1 n + 1 - m ) )
Wherein, c K+m, h pThe time domain channel value of representing h the sample point in k+m pilot tone OFDM symbol place, c (k, j), h d(n represents the number of two OFDM data symbol between the adjacent pilot frequencies OFDM symbol for k, j) the time domain channel value of h the sample point in individual OFDM data symbol place in expression the.
When adopting 1 Lagrange interpolation, promptly during linear interpolation, top formula can be reduced to:
c ( k , j ) , h d = c k , h p + j + 1 n + 1 · ( c k + 1 , h p - c k , h p )
Wherein, c K, h pThe time domain channel value of representing h the sample point in k pilot tone OFDM symbol place, c (k, j), h d(k, j) the time domain channel value of h the sample point in individual OFDM data symbol place are represented the number of the OFDM data symbol between two adjacent pilot frequencies OFDM symbols in expression the.
So far, estimate to have obtained (c S, 0 d, c S, 1 d..., c S, N ' d) value, add N thereafter D, data-N ' is individual 0, has just obtained the time domain channel response (c at the OFDM data symbol place channel of b transmitting antenna S, 0 d, c S, 1 d..., c S, N ' d, 0 ..., 0).
The time domain channel response at the OFDM data symbol place channel of a certain transmitting antenna that step 14, utilization obtain above obtains the domain channel response at the corresponding data OFDM symbol place of this transmitting antenna;
Time domain channel response (c to s OFDM data symbol place channel of the time domain that obtains S, 0 d, c S, 1 d..., c S, N ' d, 0 ..., 0), carry out IFFT, obtain the domain channel response of s OFDM data symbol place channel
After the domain channel response that has obtained OFDM data symbol place channel, just can carry out channel equalization, and then recover the data of emission the OFDM data symbol that receives.
In above-mentioned step 12, except adopting above-mentioned simple channel information extracting method---the intercept method, can also adopt a kind of comparatively complicated method, be called adaptive channel information extracting method among the present invention:
With simple channel information extracting method---the simple truncation method is different, adaptive channel information extracting method is by the time domain channel response of pilot tone OFDM symbol that a period of time is received continuously
Figure G2005101213190D00173
Analyze, utilize certain rule, extract wherein part conduct and for example, in a period of time, can select at the effective diameter of a certain transmitting antenna b
Figure G2005101213190D00174
As this section time efficient channel information.Add 0 in the appropriate location of above-mentioned effective channel information, the channel of gained extracts the time domain channel estimation procedure at the OFDM data symbol place of a certain transmitting antenna b that the result further is applied to step 13.
A simplification---the adaptive intercept method of above-mentioned adaptive approach, promptly the length of blocking of pilot tone OFDM symbol is not used and fixedly blocked length, employedly block length N ' depend on time domain reaction one section pilot tone OFDM symbol that receives continuously continuous time
Figure G2005101213190D00181
The analysis conclusion, follow-up processing procedure also can be used the different length of blocking at different transmitting antennas in addition with the described unanimity in front.
Estimate that at the another one receiver channel of realizing present embodiment with reference to Figure 14, concrete channel estimation process comprises following step in the implementation:
Step 21 is obtained the time domain channel information of pilot tone OFDM symbol from the time domain pilot OFDM symbol that receives;
Step 22, from the corresponding different transmit antennas of the time domain channel information extraction of described pilot tone OFDM symbol at corresponding pilot tone OFDM symbol place time domain channel response, for example Jing delay, attenuation directly;
The time domain channel response at the pilot tone OFDM symbol place of a certain transmitting antenna that step 23, utilization obtain above obtains the domain channel response at the corresponding pilot tone OFDM symbol place of respective transmit antenna;
Step 24, utilization is at the domain channel response at the adjacent pilot frequencies OFDM symbol place of a certain transmitting antenna, utilize specific interpolation method to estimate the domain channel response at the OFDM data symbol place of respective transmit antenna, the interpolation method that is adopted can be 2l-1 Lagrange interpolation method, especially, can use Lagrange interpolation method, i.e. linear interpolation method 1 time;
Can further carry out other operations such as channel equalization after the above-mentioned domain channel response that obtains at the OFDM data symbol of a certain transmitting antenna.
Second embodiment
Be not limited to the pilot tone OFDM symbol of above-mentioned rule and the situation that OFDM data distributes in the present embodiment, in irregular pilot tone OFDM symbol and OFDM data distribution scenario, each transmitting antenna adopts identical pilot frequency distribution pattern, a kind of irregular pilot tone OFDM symbol and OFDM data distribution scenario as shown in figure 15:
In above-mentioned irregular pilot tone OFDM symbol and OFDM data distribution scenario, the relation of each different transmit antennas between the emission symbol on the pilot sub-carrier is identical with first embodiment.
The distribution pattern of present embodiment pilot tone OFDM symbol is applicable to channel variation situation slowly, and is corresponding with the distribution of above-mentioned pilot tone OFDM symbol, and with reference to Figure 16, the respective receiver channel estimating can realize by following step:
Step 31 is obtained the channel information of pilot tone OFDM symbol time domain from the time domain pilot OFDM symbol that receives;
Step 32, from the corresponding different transmit antennas of the time domain channel information extraction of pilot tone OFDM symbol channel at corresponding pilot tone OFDM symbol place time domain channel response, for example Jing delay, attenuation directly;
The time domain channel response at the pilot tone OFDM symbol place channel of a certain transmitting antenna that step 33, utilization obtain above obtains the domain channel response at the corresponding pilot tone OFDM symbol place of respective transmit antenna;
Step 34, utilize the domain channel response of resulting pilot tone OFDM symbol at a certain transmitting antenna, in conjunction with certain correction, as thereafter, and the domain channel response at the OFDM data symbol of a certain transmitting antenna before the next pilot tone OFDM symbol.
Above-mentioned obtaining can be further used for other operations such as channel equalization at the domain channel response of the OFDM data symbol of a certain transmitting antenna.
The 3rd embodiment
Be not limited to the pilot frequency distribution mode of above-mentioned pilot tone OFDM symbol in the present embodiment, situation in the pilot frequency distribution pattern of pilot tone lattice point, each transmitting antenna adopts identical pilot frequency distribution pattern, the pilot tone lattice point that is applicable to a kind of situation of the present invention as shown in figure 17:
In the situation of the pilot frequency distribution pattern of pilot tone lattice point, the relation of each different transmit antennas between the emission symbol on the pilot sub-carrier is identical with first embodiment.
With reference to Figure 18, be applicable to that the concrete channel estimation process of receiver of the pilot frequency distribution pattern of above-mentioned time-frequency plane comprises following step:
Step 41 is isolated the frequency domain received signal of the subcarrier at pilot tone place from the frequency domain received signal that receives;
Step 42, the frequency-region signal that receives from the pilot sub-carrier that is positioned at same OFDM symbol obtains the time domain channel information of corresponding OFDM symbol;
Step 43 is from the time domain channel response of the corresponding different transmit antennas of the time domain channel information extraction of the above-mentioned corresponding OFDM symbol that obtains at corresponding OFDM symbol place, the attenuation in for example Jing delay, footpath;
Step 44 is utilized the above-mentioned adjacent time domain channel response that comprises the OFDM symbol place of pilot sub-carrier at a certain transmitting antenna that obtains, and utilizes the time domain channel response of specific interpolation method estimation at the OFDM symbol place that comprises data of this transmitting antenna;
The time domain channel response at the OFDM symbol place channel that comprises data of a certain transmitting antenna that step 45, utilization obtain above obtains the domain channel response at the subcarrier place of the correspondence carrying data of this transmitting antenna.
The above-mentioned domain channel response at a certain transmitting antenna that obtains can be further used for other operations such as channel equalization.
Estimate that at the another one receiver channel of realizing present embodiment with reference to Figure 19, concrete channel estimation process comprises following step in the implementation:
Step 51 is isolated the frequency domain received signal of pilot sub-carrier from the frequency domain received signal that receives;
Step 52, the frequency-region signal that receives from the pilot sub-carrier that is positioned at same OFDM symbol obtains the time domain channel information of corresponding OFDM symbol;
Step 53 is from the time domain channel response of the corresponding different transmit antennas of the time domain channel information extraction of the above-mentioned corresponding OFDM symbol that obtains at corresponding OFDM symbol place, the attenuation in for example Jing delay, footpath;
The time domain channel response at the OFDM symbol place channel that comprises pilot sub-carrier of a certain transmitting antenna that step 54, utilization obtain above obtains the domain channel response at the corresponding OFDM symbol place of this transmitting antenna;
Step 55, utilize the above-mentioned domain channel response that obtains at the OFDM symbol place that comprises pilot sub-carrier of a certain transmitting antenna, utilize the domain channel response of specific interpolation method estimation at the OFDM symbol place that comprises data of this transmitting antenna, the concrete interpolation method that is adopted can be 2l-1 Lagrange interpolation method, especially, can use Lagrange interpolation method, i.e. linear interpolation method 1 time;
The above-mentioned domain channel response at a certain transmitting antenna that obtains can be further used for other operations such as channel equalization.
The following describes another aspect of the present invention.
With reference to Figure 20, this figure is the realization block diagram of channel estimating apparatus in the multiple transmit antennas ofdm system of the present invention, mainly comprises:
Receiving system 61 is used to receive different transmit antennas by identical pilot frequency mode pilot transmitted data;
Pilot frequency information separator 62 is used for separating the pilot frequency information that receives, the frequency-region signal that obtains receiving on the pilot sub-carrier according to described pilot frequency mode;
Time domain channel response deriving means 63 according to the frequency-region signal that receives on the pilot sub-carrier that is positioned at same orthogonal multi-path frequency-division duplicating symbol, obtains the time domain channel response of different transmit antennas at this orthogonal multi-path frequency-division duplicating symbol place;
Domain channel response deriving means 64 is estimated the domain channel response at corresponding different transmit antennas data subcarrier place with the time domain channel response of the described different transmit antennas that obtains.
Described time domain channel response deriving means at first is described, with reference to Figure 21, described time domain channel response deriving means comprises:
Time domain channel information acquisition unit 631, according to the frequency-region signal that receives on the pilot sub-carrier that is positioned at same OFDM symbol, obtain the time domain channel information at this OFDM symbol place, during specific implementation, described time domain channel information acquisition unit can comprise:
First obtains subelement, frequency-region signal according to described reception, and the domain data information on the pilot sub-carrier in the respective orthogonal frequency division multiplexing symbol of transmitting terminal emission, obtain the domain channel response at corresponding pilot sub-carrier place on the respective orthogonal frequency division multiplexing symbol;
Second obtains subelement, obtains the time domain channel information of respective orthogonal frequency division multiplexing symbol place pilot sub-carrier according to described domain channel response;
Time domain channel response extraction unit 632, the time domain channel response of the corresponding different transmit antennas of extraction from the described time domain channel information that obtains, during specific implementation, the realization of a kind of optional embodiment of described time domain channel response extraction unit can comprise:
First determines subelement, according to the time delay expansion that system supported, determines the scope of blocking at b transmitting antenna from the time domain channel reaction that obtains;
First time domain channel response extracts subelement, obtain the time domain channel value of the scope of blocking correspondence in described time domain channel information of b transmitting antenna, replace the time domain channel value clipped in the described time domain channel reaction with 0, with the above-mentioned time domain channel sequence of the obtaining translation N that circulates forward bIndividual, obtain the time domain channel response of b transmitting antenna, wherein N bBe b transmitting antenna channel delay corresponding sampling points number.
In addition, the another kind of optional embodiment of described time domain channel response extraction unit specifically can comprise:
Second determines subelement, and the scope of blocking of b transmitting antenna is determined in the time domain channel reaction at the OFDM symbol place by analyzing continuous time;
Second time domain channel response extracts subelement, obtain the time domain channel value that this blocks scope correspondence in described time domain channel information, and replace not selected time domain channel value in the described time domain channel reaction with 0, with the above-mentioned time domain channel sequence of the obtaining translation N that circulates forward bIndividual, obtain the time domain channel response of b transmitting antenna, wherein N bBe b transmitting antenna channel delay corresponding sampling points number.
The following describes domain channel response deriving means of the present invention, with reference to Figure 22, the composition of described domain channel response deriving means first embodiment can comprise:
Interpolation estimation unit 6411, estimate by the time domain channel response at the OFDM symbol place that comprises pilot sub-carrier of different transmit antennas that obtains is carried out interpolation, obtain at the adjacent of respective transmit antenna and comprise the time domain channel response at the OFDM symbol place of data with the described OFDM symbol that comprises pilot sub-carrier;
The first domain channel response acquiring unit 6412, the above-mentioned time domain channel response at the OFDM symbol place that comprises data of respective transmit antenna that obtains is carried out inverse fourier transform, obtain corresponding domain channel response at described respective transmit antenna.
With reference to Figure 23, the composition of described domain channel response deriving means second embodiment can comprise:
The second domain channel response acquiring unit 6421 obtains corresponding domain channel response at respective transmit antenna according to the time domain channel response at the OFDM symbol place that comprises pilot sub-carrier of a certain transmitting antenna;
The 3rd domain channel response acquiring unit 6422, according to the domain channel response at the OFDM symbol place that comprises pilot sub-carrier of respective transmit antenna of gained, estimate at the adjacent of respective transmit antenna and comprise the domain channel response at the OFDM symbol place of data with the described OFDM symbol that comprises pilot sub-carrier.
Wherein, described the 3rd domain channel response acquiring unit obtains domain channel response and can adopt directly the domain channel response at the OFDM symbol place that comprises pilot sub-carrier of gained as adjacent with described OFDM symbol and comprise the domain channel response at the OFDM symbol place of data; Or
Domain channel response to the OFDM symbol place that comprises pilot sub-carrier of gained is revised, and with revised domain channel response as adjacent with described OFDM symbol and comprise the domain channel response at the OFDM symbol place of data; Or
The domain channel response at the OFDM symbol place that comprises pilot sub-carrier is carried out interpolation estimate, obtain adjacent and comprise the domain channel response at the OFDM symbol place of data with described OFDM symbol.
Similarly, described interpolation is estimated to adopt 2 l-1 lagrange-interpolation or 1 Lagrange's interpolation algorithm.
The present invention program can change the preferable performance that obtains under situation and the high latency situation at channel circumstance.Specifically, by the present invention program, with respect to desirable channel estimating, with respect to desirable channel estimating, block the footpath number is 32 o'clock, the channel estimation results under Vehicle A channel, the 30kmph situation as shown in figure 24, performance loss is less than 0.3dB; Channel estimation results under Vehicle A channel, the 60kmph situation as shown in figure 25, performance loss is less than 1.1dB.Blocking the footpath number is 160 o'clock, and under the situation of Vehicle B channel, 30kmph, as shown in figure 26, the channel estimating that adopts the present invention program to obtain estimates that with respect to ideal communication channel performance loss is also less than 0.7dB.
The above only is a preferred implementation of the present invention; should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the principle of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (28)

1. the launching technique of pilot data in the multiple transmit antennas ofdm system is characterized in that described method comprises:
Different transmit antennas is by identical pilot frequency mode emission pilot data, the emission symbol difference of each different transmit antennas on pilot sub-carrier;
The relation of described each different transmit antennas between the emission symbol on the pilot sub-carrier satisfies following formula:
D b ′ k , j = e i · 2 π ( τ b - τ b ′ ) · Δf · j D b k , j
Wherein, b, b ' are respectively b numbering that reaches the individual transmitting antenna of b ', b＜b ', D b K, j, D b' K, jBe respectively b j the frequency-region signal that subcarrier carried that reaches k pilot tone OFDM symbol of the individual transmission antennas transmit of b ', τ b, τ B 'Be respectively and b and the relevant time delay information of the individual transmitting antenna of b ', τ 1≤ τ b＜τ B ', τ 1Be the 1st the relevant time delay information of transmitting antenna, and τ B+1-τ bGreater than the time delay τ of channel, Δ f is the minimum frequency space between the subcarrier.
2. the launching technique of pilot data is characterized in that in the multiple transmit antennas ofdm system as claimed in claim 1, the time delay spacing equalization of described each different transmit antennas.
3. the launching technique of pilot data in the multiple transmit antennas ofdm system as claimed in claim 1 or 2, it is characterized in that described pilot frequency mode is that pilot tone OFDM symbol and OFDM data symbol are in regular distribution pattern, pilot tone OFDM symbol and OFDM data symbol on the time-domain irregular distribution pattern or pilot tone lattice point pattern on time-domain.
4. a multi-antenna orthogonal frequency division multiplexing system base station controller includes the base station control unit, it is characterized in that, described base station control unit includes:
Many antennas emission controlling unit is used to control different transmitting antennas by identical pilot frequency mode emission pilot data, wherein the emission symbol difference of each different transmit antennas on pilot sub-carrier;
The relation of described each different transmit antennas between the emission symbol on the pilot sub-carrier satisfies following formula:
D b ′ k , j = e i · 2 π ( τ b - τ b ′ ) · Δf · j D b k , j
Wherein, b, b ' are respectively b numbering that reaches the individual transmitting antenna of b ', b＜b ', D b K, j, D b' K, jBe respectively b j the frequency-region signal that subcarrier carried that reaches k pilot tone OFDM symbol of the individual transmission antennas transmit of b ', τ b, τ B 'Be respectively and b and the relevant time delay information of the individual transmitting antenna of b ', τ 1≤ τ b＜τ B ', τ 1Be the 1st the relevant time delay information of transmitting antenna, and τ B+1-τ bGreater than the time delay τ of channel, Δ f is the minimum frequency space between the subcarrier.
5. base station controller according to claim 4 is characterized in that, the time delay spacing equalization of described each different transmit antennas.
6. according to claim 4 or 5 described base station controllers, it is characterized in that described pilot frequency mode is that pilot tone OFDM symbol and OFDM data symbol are in regular distribution pattern, pilot tone OFDM symbol and OFDM data symbol on the time-domain irregular distribution pattern or pilot tone lattice point pattern on time-domain.
7. channel estimation methods in the multiple transmit antennas ofdm system is characterized in that, comprising:
A. receive the mode pilot transmitted data of different transmit antennas by claim 1;
B. separate the pilot frequency information that receives, the frequency-region signal that obtains receiving on the pilot sub-carrier according to described pilot frequency mode;
C. according to being positioned at the frequency-region signal that receives on the pilot sub-carrier of same orthogonal multi-path frequency-division duplicating symbol, obtain the time domain channel response of different transmit antennas at this orthogonal multi-path frequency-division duplicating symbol place;
D. estimate the domain channel response at corresponding different transmit antennas data subcarrier place with the time domain channel response of the described different transmit antennas that obtains.
8. channel estimation methods in the multiple transmit antennas ofdm system according to claim 7 is characterized in that, described step c comprises:
C1. according to being positioned at the frequency-region signal that receives on the pilot sub-carrier of same OFDM symbol, obtain the time domain channel information at this OFDM symbol place;
C2. from the described time domain channel information that obtains, extract the time domain channel response of corresponding different transmit antennas.
9. channel estimation methods in the multiple transmit antennas ofdm system according to claim 8 is characterized in that, described step c1 may further comprise the steps:
C11. according to the frequency-region signal of described reception, and the domain data information on the pilot sub-carrier in the respective orthogonal frequency division multiplexing symbol of transmitting terminal emission, obtain the domain channel response at corresponding pilot sub-carrier place on the respective orthogonal frequency division multiplexing symbol;
C12. obtain the time domain channel information of respective orthogonal frequency division multiplexing symbol place pilot sub-carrier according to described domain channel response.
10. channel estimation methods in the multiple transmit antennas ofdm system according to claim 8 is characterized in that, each transmitting antenna of described step c2 obtains separately time domain channel response according to following method:
According to the time delay expansion that system supported, from the time domain channel reaction that obtains, determine the scope of blocking at b transmitting antenna;
The scope of blocking of obtaining b transmitting antenna corresponding time domain channel value in described time domain channel information replaces the time domain channel value that quilt is clipped in the described time domain channel reaction with 0, with the above-mentioned time domain channel sequence of the obtaining translation N that circulates forward bIndividual, obtain the time domain channel response of b transmitting antenna, wherein N bBe b transmitting antenna channel delay corresponding sampling points number.
11. channel estimation methods in the multiple transmit antennas ofdm system according to claim 8 is characterized in that, each transmitting antenna of described step c2 obtains separately time domain channel response according to following method:
The time domain channel response at the OFDM symbol place by analyzing continuous time is determined the scope of blocking of b transmitting antenna;
Obtain this and block scope corresponding time domain channel value in described time domain channel information, and with 0 replace described time domain channel react in not selected time domain channel value, with the above-mentioned time domain channel sequence of the obtaining translation N that circulates forward bIndividual, obtain the time domain channel response of b transmitting antenna, wherein N bBe b transmitting antenna channel delay corresponding sampling points number.
12. channel estimation methods in the multiple transmit antennas ofdm system according to claim 7 is characterized in that, described steps d may further comprise the steps:
D11. estimate by the time domain channel response at the OFDM symbol place that comprises pilot sub-carrier of different transmit antennas that obtains is carried out interpolation, obtain at the adjacent of respective transmit antenna and comprise the time domain channel response at the OFDM symbol place of data with the described OFDM symbol that comprises pilot sub-carrier;
D12. the above-mentioned time domain channel response at the OFDM symbol place that comprises data of respective transmit antenna that obtains is carried out inverse fourier transform, obtain corresponding domain channel response at described respective transmit antenna.
13. channel estimation methods in the multiple transmit antennas ofdm system according to claim 7 is characterized in that, described steps d may further comprise the steps:
D21. obtain corresponding domain channel response according to time domain channel response at respective transmit antenna at the OFDM symbol place that comprises pilot sub-carrier of a certain transmitting antenna;
D22. according to the domain channel response at the OFDM symbol place that comprises pilot sub-carrier of respective transmit antenna of gained, estimate at the adjacent of respective transmit antenna and comprise the domain channel response at the OFDM symbol place of data with the described OFDM symbol that comprises pilot sub-carrier.
14. channel estimation methods in the multiple transmit antennas ofdm system according to claim 13, it is characterized in that described steps d 22 is: directly with the domain channel response at the OFDM symbol place that comprises pilot sub-carrier of gained as adjacent with described OFDM symbol and comprise the domain channel response at the OFDM symbol place of data.
15. channel estimation methods in the multiple transmit antennas ofdm system according to claim 13, it is characterized in that, described steps d 22 is: the domain channel response to the OFDM symbol place that comprises pilot sub-carrier of gained is revised, and with revised domain channel response as adjacent with described OFDM symbol and comprise the domain channel response at the OFDM symbol place of data.
16. channel estimation methods in the multiple transmit antennas ofdm system according to claim 13, it is characterized in that, described steps d 22 is: the domain channel response at the OFDM symbol place that comprises pilot sub-carrier is carried out interpolation estimate, obtain adjacent with described OFDM symbol and comprise the domain channel response at the OFDM symbol place of data.
17., it is characterized in that described interpolation is estimated to adopt 2 according to channel estimation methods in claim 12 or the 16 described multiple transmit antennas ofdm systems l-1 lagrange-interpolation or 1 Lagrange's interpolation algorithm.
18. channel estimating apparatus in the multiple transmit antennas ofdm system is characterized in that, comprising:
Receiving system is used to receive the mode pilot transmitted data of different transmit antennas by claim 1;
The pilot frequency information separator is used for separating the pilot frequency information that receives, the frequency-region signal that obtains receiving on the pilot sub-carrier according to described pilot frequency mode;
The time domain channel response deriving means according to the frequency-region signal that receives on the pilot sub-carrier that is positioned at same orthogonal multi-path frequency-division duplicating symbol, obtains the time domain channel response of different transmit antennas at this orthogonal multi-path frequency-division duplicating symbol place;
The domain channel response deriving means is estimated the domain channel response at corresponding different transmit antennas data subcarrier place with the time domain channel response of the described different transmit antennas that obtains.
19. channel estimating apparatus in the multiple transmit antennas ofdm system according to claim 18 is characterized in that, described time domain channel response deriving means comprises:
The time domain channel information acquisition unit according to the frequency-region signal that receives on the pilot sub-carrier that is positioned at same OFDM symbol, is obtained the time domain channel information at this OFDM symbol place;
The time domain channel response extraction unit, the time domain channel response of the corresponding different transmit antennas of extraction from the described time domain channel information that obtains.
20. channel estimating apparatus in the multiple transmit antennas ofdm system according to claim 19 is characterized in that, described time domain channel information acquisition unit comprises:
First obtains subelement, frequency-region signal according to described reception, and the domain data information on the pilot sub-carrier in the respective orthogonal frequency division multiplexing symbol of transmitting terminal emission, obtain the domain channel response at corresponding pilot sub-carrier place on the respective orthogonal frequency division multiplexing symbol;
Second obtains subelement, obtains the time domain channel information of respective orthogonal frequency division multiplexing symbol place pilot sub-carrier according to described domain channel response.
21. channel estimating apparatus in the multiple transmit antennas ofdm system according to claim 19 is characterized in that, described time domain channel response extraction unit comprises:
First determines subelement, according to the time delay expansion that system supported, determines the scope of blocking at b transmitting antenna from the time domain channel reaction that obtains;
First time domain channel response extracts subelement, obtain the time domain channel value of the scope of blocking correspondence in described time domain channel information of b transmitting antenna, replace the time domain channel value clipped in the described time domain channel reaction with 0, with the above-mentioned time domain channel sequence of the obtaining translation N that circulates forward bIndividual, obtain the time domain channel response of b transmitting antenna, wherein N bBe b transmitting antenna channel delay corresponding sampling points number.
22. channel estimating apparatus in the multiple transmit antennas ofdm system according to claim 19 is characterized in that, described time domain channel response extraction unit comprises:
Second determines subelement, and the time domain channel response at the OFDM symbol place by analyzing continuous time is determined the scope of blocking of b transmitting antenna;
Second time domain channel response extracts subelement, obtain the time domain channel value that this blocks scope correspondence in described time domain channel information, and replace not selected time domain channel value in the described time domain channel reaction with 0, with the above-mentioned time domain channel sequence of the obtaining translation N that circulates forward bIndividual, obtain the time domain channel response of b transmitting antenna, wherein N bBe b transmitting antenna channel delay corresponding sampling points number.
23. channel estimating apparatus in the multiple transmit antennas ofdm system according to claim 18 is characterized in that, described domain channel response deriving means comprises:
The interpolation estimation unit, estimate by the time domain channel response at the OFDM symbol place that comprises pilot sub-carrier of different transmit antennas that obtains is carried out interpolation, obtain at the adjacent of respective transmit antenna and comprise the time domain channel response at the OFDM symbol place of data with the described OFDM symbol that comprises pilot sub-carrier;
The first domain channel response acquiring unit, the above-mentioned time domain channel response at the OFDM symbol place that comprises data of respective transmit antenna that obtains is carried out inverse fourier transform, obtain corresponding domain channel response at described respective transmit antenna.
24. channel estimating apparatus in the multiple transmit antennas ofdm system according to claim 18 is characterized in that, described domain channel response deriving means comprises:
The second domain channel response acquiring unit obtains corresponding domain channel response at respective transmit antenna according to the time domain channel response at the OFDM symbol place that comprises pilot sub-carrier of a certain transmitting antenna;
The 3rd domain channel response acquiring unit, according to the domain channel response at the OFDM symbol place that comprises pilot sub-carrier of respective transmit antenna of gained, estimate at the adjacent of respective transmit antenna and comprise the domain channel response at the OFDM symbol place of data with the described OFDM symbol that comprises pilot sub-carrier.
25. channel estimating apparatus in the multiple transmit antennas ofdm system according to claim 24, it is characterized in that described the 3rd domain channel response acquiring unit obtains domain channel response and is: directly with the domain channel response at the OFDM symbol place that comprises pilot sub-carrier of gained as adjacent with described OFDM symbol and comprise the domain channel response at the OFDM symbol place of data.
26. channel estimating apparatus in the multiple transmit antennas ofdm system according to claim 24, it is characterized in that, described the 3rd domain channel response acquiring unit obtains domain channel response and is: the domain channel response to the OFDM symbol place that comprises pilot sub-carrier of gained is revised, and with revised domain channel response as adjacent with described OFDM symbol and comprise the domain channel response at the OFDM symbol place of data.
27. channel estimating apparatus in the multiple transmit antennas ofdm system according to claim 24, it is characterized in that, described the 3rd domain channel response acquiring unit obtains domain channel response and is: the domain channel response at the OFDM symbol place that comprises pilot sub-carrier is carried out interpolation estimate, obtain adjacent with described OFDM symbol and comprise the domain channel response at the OFDM symbol place of data.
28., it is characterized in that described interpolation is estimated to adopt 2 according to channel estimating apparatus in claim 23 or the 27 described multiple transmit antennas ofdm systems l-1 lagrange-interpolation or 1 Lagrange's interpolation algorithm.
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