WO2017181827A1 - 传输导频信号的方法和设备 - Google Patents

传输导频信号的方法和设备 Download PDF

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Publication number
WO2017181827A1
WO2017181827A1 PCT/CN2017/078618 CN2017078618W WO2017181827A1 WO 2017181827 A1 WO2017181827 A1 WO 2017181827A1 CN 2017078618 W CN2017078618 W CN 2017078618W WO 2017181827 A1 WO2017181827 A1 WO 2017181827A1
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WIPO (PCT)
Prior art keywords
pilot
zero
sequence
pilot sequence
interference
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PCT/CN2017/078618
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English (en)
French (fr)
Inventor
黄煌
文荣
明尼海莱恩
凯瑟菲德艾米
艾达尔郎弗
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Huawei Technologies Co Ltd
University of Texas System
University of Texas at Austin
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Huawei Technologies Co Ltd
University of Texas System
University of Texas at Austin
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Publication of WO2017181827A1 publication Critical patent/WO2017181827A1/zh
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/003—Arrangements for allocating sub-channels of the transmission path
    • H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes

Definitions

  • the present application relates to the field of communications and, more particularly, to a method and apparatus for transmitting pilot signals.
  • Pilot signals also known as pilot sequences, include non-zero pilots and zero pilots (also known as null pilots). Pilot sequences are commonly used for channel estimation and Radio Frequency Distortion compensation in communication systems. The characteristics of the channel and RF distortion depend on factors such as the environment, frequency range, system settings, and transceiver implementation errors. Therefore, the design of pilot sequences under different conditions is also different. In addition, when pilot signals are transmitted in the frequency domain or transmitted in the time domain, their design is also different.
  • the pilot signals in the frequency domain are mainly applied to a multi-carrier system such as an Orthogonal Frequency Division Multiplexing (OFDM) system or a Single-Carrier Frequency-Division Multiple Access (SC-FDMA) system. And Discrete Fourier Transform-Precoded OFDM (DFT-precoded OFDM) system and the like.
  • the pilot signal can be used to estimate the channel and estimate interference under radio frequency distortion conditions, such as phase noise, frequency offset, and in-phase and quadrature-phase Imbalance (IQI), and can also be used for single carrier.
  • System frequency domain equalization such as phase noise, frequency offset, and in-phase and quadrature-phase Imbalance (IQI), and can also be used for single carrier.
  • the design scheme of the existing pilot sequence is mainly divided into the design of the pilot sequence without radio frequency distortion and the pilot sequence design under the condition of radio frequency distortion.
  • the existing pilot sequence design under RF distortion conditions mainly includes pilot sequence design for channel + IQI, pilot sequence design for channel + phase noise, and pilot sequence design for channel + phase noise + frequency offset. and many more.
  • the pilot sequence design for Inter-Carrier/Inter-sub-Carrier Interference (ICI) caused by phase noise and Mirror Tone Interference (MTI) caused by IQI is less.
  • the present application provides a method and apparatus for transmitting a pilot signal, which can reduce the influence of radio frequency distortion on the system and improve the performance of the system.
  • a method for transmitting a pilot signal comprising: determining a pilot interval of any two adjacent non-zero pilots in a pilot sequence, the pilot interval being based on a radio frequency distortion condition Deriving an extension length of the interference; generating the pilot sequence according to the pilot interval, where a pilot between any two adjacent non-zero pilots in the pilot sequence is zero pilot, the guide The mirror subcarrier corresponding to the subcarrier of the non-zero pilot of the frequency sequence is an empty subcarrier; the pilot sequence is transmitted.
  • the method may include: generating a pilot sequence, wherein pilot intervals of any two adjacent non-zero pilots in the pilot sequence are determined according to an extended length of interference under radio frequency distortion conditions, The pilot between any two adjacent non-zero pilots in the pilot sequence is a zero pilot, and the mirror subcarrier corresponding to the subcarrier of the non-zero pilot is a null subcarrier; the pilot sequence is transmitted.
  • the method may include: determining a pilot interval of any two adjacent non-zero pilots in the pilot sequence, the pilot interval being greater than or equal to 1; generating the guide according to the pilot interval a frequency sequence, where pilots between any two adjacent non-zero pilots in the pilot sequence are zero pilots, and a mirror subcarrier corresponding to a non-zero pilot subcarrier of the pilot sequence is a null subcarrier Sending the pilot sequence.
  • the method may include: generating a pilot sequence, where a pilot interval of any two adjacent non-zero pilots in the pilot sequence is greater than or equal to 1, and any two adjacent non-contiguous pilot sequences
  • the pilot between the zero pilots is a zero pilot, and the mirror subcarrier corresponding to the subcarrier of the non-zero pilot is a null subcarrier; the pilot sequence is transmitted.
  • a non-zero pilot carrier is allocated to the system, and a zero pilot carrier is also allocated to the system.
  • the pilot interval design of the non-zero pilot is based on the principle of not being interfered, so that the non-zero pilot carrier is used. And the impact of data interference is significantly weakened, which makes the system less affected by RF distortion and improves system performance.
  • the extended length includes an inter-carrier interference ICI extension length and a mirror interference MTI extension length.
  • the interference includes inter-carrier interference ICI and image interference MTI.
  • the subcarriers adjacent to each other of the mirror subcarriers corresponding to the subcarriers of the non-zero pilot are empty subcarriers.
  • the pilot sequence is used to estimate an equivalent channel gain, where the pilot interval causes an interference to affect a non-zero pilot to be less than a first threshold, according to the Generating the pilot sequence by a pilot interval includes generating the pilot sequence based on the pilot interval and an equivalent channel coherence bandwidth of the system.
  • the scenario for estimating the equivalent channel gain is designed such that the pilot sequence of the pilot sequence is equivalent to the interference interval, so that the influence of the interference on the non-zero pilot is less than the first threshold, and the pilot sequence is finally equivalent.
  • the pilot spacing is less than or equal to the equivalent channel coherence bandwidth of the system.
  • the pilot sequence is used to estimate at least two types of interference in a radio frequency distortion condition, where the pilot interval is such that the at least two types of interference are non-zero pilots The influence is less than the first threshold, and the pilot interval is such that the influence of the at least two interferences relative to each other is less than the second threshold.
  • the method further includes: sending the pilot sequence, including: sending the pilot sequence on a corresponding symbol; the method further comprising: sending data on the symbol signal.
  • the pilot sequence includes a first type of pilot sequence and a second type of pilot sequence, where the first type of pilot sequence is used to estimate an equivalent channel gain, a pilot interval of any two adjacent non-zero pilots in the first type of pilot sequence is a first pilot interval, and the second type of pilot sequence is used to estimate a radio frequency loss At least two types of interferences in a true condition, a pilot interval of any two adjacent non-zero pilots in the second type of pilot sequence is a second pilot interval, and the generating is performed according to the pilot interval
  • the pilot sequence includes: generating the first type of pilot sequence, the first type of pilot sequence being generated according to the first pilot interval and an equivalent channel coherence bandwidth of the system, the first pilot interval The interference on the non-zero pilot is less than the first threshold; the second type of pilot sequence is generated, and the second type of pilot sequence is generated according to the second pilot interval, in the second type of pilot sequence
  • the second pilot spacing of any two adjacent non-zero pilots causes the interference to have a
  • the pilot sequence is generated by concatenating a plurality of basic pilot units, where the basic pilot unit includes a non-zero pilot.
  • a method for transmitting a pilot signal comprising: acquiring an inter-carrier interference ICI extension length and a picture interference MTI extension length under radio frequency distortion conditions; and extending the length according to the ICI and the MTI extension Length, determining a non-zero pilot minimum anti-interference distance; generating a pilot sequence according to the non-zero pilot minimum anti-interference distance, and pilot intervals of any two adjacent non-zero pilots in the pilot sequence Greater than or equal to the non-zero pilot minimum anti-interference distance, the pilot between any two adjacent non-zero pilots in the pilot sequence is zero pilot, and the non-zero pilot subcarrier corresponds to The mirrored subcarrier is an empty subcarrier; the pilot sequence is transmitted.
  • the method includes: determining a non-zero pilot minimum anti-interference distance according to an inter-carrier interference ICI extension length and a picture interference MTI extension length under radio frequency distortion conditions; and determining a minimum anti-interference distance according to the non-zero pilot Generating a pilot sequence, where a pilot interval of any two adjacent non-zero pilots in the pilot sequence is greater than or equal to the non-zero pilot minimum anti-interference distance, any two of the pilot sequences
  • the pilot between adjacent non-zero pilots is zero pilot, and the mirror subcarrier corresponding to the subcarrier of the non-zero pilot is a null subcarrier; the pilot sequence is transmitted.
  • the pilot sequence is used to estimate an equivalent channel gain, where the ICI extension length is ⁇ subcarriers, and the MTI extension length is ⁇ subcarriers, Determining the non-zero pilot minimum anti-interference distance according to the ICI extension length and the MTI extension length, including: determining, according to the ICI extension length, ⁇ subcarriers and the MTI extension length being ⁇ subcarriers
  • IFD main max( ⁇ +1,2 ⁇ +2) is an optional implementation.
  • the mirror subcarriers occupy one subcarrier.
  • the MTI has a unilateral extension length of ⁇ and a bilateral extension length of 2 ⁇ .
  • the number of null carriers required is 2 ⁇ +1, and the pilot spacing of non-zero pilots needs to be greater than or equal to 2 ⁇ +2 from the MTI perspective.
  • the subcarriers adjacent to the left and right of the mirror subcarriers corresponding to the subcarriers of the non-zero pilot may be null subcarriers.
  • a specific example is that the system has a single digital channel, and the generating a pilot sequence according to the non-zero pilot minimum anti-interference distance includes: if the first non-zero pilot has minimum anti-interference The distance IFD main is less than or equal to the equivalent channel coherence bandwidth, and the pilot sequence is generated on one symbol, and the pilot intervals of any two adjacent non-zero pilots in the pilot sequence are less than or equal to the same The channel coherent bandwidth is greater than or equal to the first non-zero pilot minimum anti-interference distance; if the first non-zero pilot minimum anti-interference distance IFD main is greater than the equivalent channel coherence bandwidth, at M symbols And generating M pilot sequences, where a pilot interval of any two adjacent non-zero pilots in the pilot sequence is greater than or equal to the first non-zero pilot minimum anti-interference distance, the M guides The subcarriers corresponding to the non-zero pilots of any two pilot sequences in the frequency sequence are different, wherein M is rounded up to the IFD
  • the system has K digital channels, where K is greater than or equal to 2, and the generating a pilot sequence according to the non-zero pilot minimum anti-interference distance includes: if the a non-zero K times the minimum pilot interference from the IFD main or less equivalent channel coherence bandwidth, generating K pilot sequences on a symbol, each of the K pilot pilot pilot sequences to any sequence a pilot interval of two adjacent non-zero pilots less than or equal to the equivalent channel coherence bandwidth and greater than or equal to the first non-zero pilot minimum anti-interference distance, in the K pilot sequences
  • the subcarriers corresponding to the non-zero pilots of any two pilot sequences are different; if the K times of the first non-zero pilot minimum anti-interference distance IFD main is greater than the equivalent channel coherence bandwidth, and the first non The zero pilot minimum anti-interference distance IFD main is less than or equal to the equivalent channel coherence bandwidth, and K pilot sequences are generated on N symbols, wherein N is less than or equal to
  • the ICI extension length is ⁇ subcarriers
  • the MTI extension length is ⁇ subcarriers
  • the determining is not according to the ICI extension length and the MTI extension length.
  • pilot sequence is used to estimate the ICI and MTI, or the pilot sequence is used to estimate the equivalent channel gain and estimate the ICI and MTI.
  • a specific example is that the system has a single digital channel, and the minimum anti-interference according to the non-zero pilot a distance, generating a pilot sequence, comprising: if the length of the pilot sequence is less than or equal to a pilot available channel bandwidth on one symbol, a contiguous subcarrier group on the left side of the DC carrier of one symbol and a continuous subcarrier on the right side Generating, by the group, a pilot sequence including V non-zero pilots, where a pilot interval of any two adjacent non-zero pilots in the pilot sequence is greater than or equal to the second non-zero pilot minimum anti-interference Distance, where V is greater than 1.
  • the system has K digital channels, where K is greater than or equal to 2, and the pilot sequence is generated according to the non-zero pilot minimum anti-interference distance, including: if K numbers The total length of the pilot sequence of the channel is less than or equal to the pilot available channel bandwidth on one symbol, and K pilot sequences are generated on one symbol, and any two adjacent ones of the pilot sequences in the K pilot sequences The pilot interval of the non-zero pilot is greater than or equal to the second non-zero pilot minimum anti-interference distance, and the subcarriers corresponding to the non-zero pilots of any two of the K pilot sequences are different If the total length of the pilot sequences of the K digital channels is greater than the pilot available channel bandwidth on one symbol, K pilot sequences are generated on T symbols, where T is less than or equal to K, the pilot of the tth symbol K t pilot sequences are generated on the available channel bandwidth, and the value of t is 1, 2, ..., T, K t is less than or equal to K' 0 , and
  • the pilot sequence is generated by a cascade of basic pilot units, where the basic pilot unit includes a non-zero pilot, and the two basic pilot units are cascaded.
  • the pilot spacing of two non-zero pilots of the two basic pilot units is greater than or equal to the second non-zero pilot minimum interference rejection distance.
  • the method further includes: transmitting a data signal on the symbol of the transmitting the pilot sequence.
  • the system has a single digital channel
  • the generating a pilot sequence according to the non-zero pilot minimum anti-interference distance includes: if the second non-zero pilot a minimum anti-interference distance IFD ICI, the MTI being less than or equal to the equivalent channel coherence bandwidth, generating the pilot sequence on one symbol, the pilot spacing of any two adjacent non-zero pilots in the pilot sequence being less than Or equal to the equivalent channel coherence bandwidth, and greater than or equal to the second non-zero pilot minimum anti-interference distance; if the second non-zero pilot minimum anti-interference distance IFD ICI, the MTI is greater than the equivalent channel a U-pilot sequence is generated on the U symbols, and the sub-carriers corresponding to the non-zero pilots of any two pilot sequences in the U pilot sequences are different, and the U pilot sequences are different.
  • the pilot spacing of any two adjacent non-zero pilots in each pilot sequence is greater than or equal to the second non-zero
  • the pilot sequence can be used to estimate the equivalent channel gain and estimate the ICI and MTI.
  • the ICI extension length is ⁇ subcarriers
  • the MTI extension length is ⁇ subcarriers
  • the determining is non-zero according to the ICI extension length and the MTI extension length.
  • the pilot sequence can be used to estimate the equivalent channel gain and estimate the ICI and MTI.
  • a specific example is that the system has a single digital channel, and the generating a pilot sequence according to the non-zero pilot minimum anti-interference distance includes: generating a first type of pilot sequence on the first type of symbol, a pilot interval of any two adjacent non-zero pilots in the first type of pilot sequence is greater than or equal to the first non-zero pilot minimum anti-interference distance; after the first type of symbol Generating a second type of pilot sequence on the second type of symbols, and a pilot interval of any two adjacent non-zero pilots in the second type of pilot sequence is greater than or equal to the second non-zero pilot minimum anti-interference distance.
  • the first non-zero pilot minimum anti-interference distance IFD main is less than or equal to the equivalent channel coherence bandwidth, generate a first type of pilot sequence on a first type of symbol, the first type of pilot a pilot interval of any two adjacent non-zero pilots in the sequence is greater than or equal to the first non-zero pilot minimum anti-interference distance and less than or equal to the equivalent channel coherence bandwidth; if the first The non-zero pilot minimum anti-interference distance IFD main is greater than the equivalent channel coherence bandwidth, and Y first-class pilot sequences are generated on Y symbols, and any two adjacent ones of the first-type pilot sequences are adjacent The pilot interval of the non-zero pilot is greater than or equal to the first non-zero pilot minimum anti-interference distance, and the non-zero pilot of any two of the Y first-class pilot sequences Corresponding subcarriers are different, wherein Y is rounded off the IFD main / equivalent channel coherent bandwidth; a second type of pilot sequence is generated
  • the system has K digital channels, where K is greater than or equal to 2, and the generating a pilot sequence according to the non-zero pilot minimum anti-interference distance includes: if the Two non-zero pilot minimum anti-interference distance IFD ICI, K times the MTI is less than or equal to the equivalent channel coherence bandwidth, generating K pilot sequences on one symbol, each pilot sequence in the K pilot sequences a pilot interval of any two adjacent non-zero pilots is less than or equal to the equivalent channel coherence bandwidth and greater than or equal to the second non-zero pilot minimum anti-interference distance, the K pilot sequences The subcarriers corresponding to the non-zero pilots of any two pilot sequences are different; if the second non-zero pilot minimum anti-interference distance IFD ICI, the K times of the MTI is greater than the equivalent channel coherence bandwidth, and The second non-zero pilot minimum anti-interference distance IFD ICI, the MTI is less than or equal to the equivalent channel coherence bandwidth, and K
  • any two adjacent non-zero pilots in the class A pilot sequence is greater than or equal to the first non-zero pilot minimum anti-interference distance
  • any two of the class B pilot sequences The pilot spacing of adjacent non-zero pilots is greater than or equal to the second non-zero pilot minimum anti-interference distance.
  • a third aspect provides a method for transmitting a pilot signal, including: receiving a pilot sequence, where pilot intervals of any two adjacent non-zero pilots in the pilot sequence are interference according to radio frequency distortion conditions Derived by the extension length, the pilot between any two adjacent non-zero pilots in the pilot sequence is zero pilot, and the mirror subcarrier corresponding to the subcarrier of the non-zero pilot is an empty subcarrier;
  • the pilot sequence estimates an equivalent channel gain or estimates at least two types of interference under radio frequency distortion conditions.
  • the method may include: receiving a pilot sequence, where a pilot interval of any two adjacent non-zero pilots in the pilot sequence is greater than or equal to 1, and any two phases in the pilot sequence a pilot between adjacent non-zero pilots is a zero pilot, and a mirror subcarrier corresponding to the subcarrier of the non-zero pilot is a null subcarrier; estimating an equivalent channel gain or estimating a radio frequency distortion condition according to the pilot sequence At least two kinds of interference.
  • the subcarriers adjacent to each of the left and right of the mirror subcarriers corresponding to the subcarriers of the non-zero pilot are also null subcarriers.
  • the pilot sequence is used to estimate an equivalent channel gain, which is generated according to an equivalent channel coherence bandwidth of the system, where the pilot interval is such that the interference is non-zero pilot.
  • the impact is less than the first threshold.
  • the pilot sequence is used to estimate at least two types of interference in a radio frequency distortion condition, where the pilot interval is such that the at least two types of interference are non-zero pilots The influence is less than the first threshold, and the pilot interval is such that the influence of the at least two interferences relative to each other is less than the second threshold.
  • the method may further include: receiving a data signal on the symbol of receiving the pilot sequence.
  • the receiving the pilot sequence includes: receiving a first type of pilot sequence on a first type of symbol, any two of the first type of pilot sequences First pilot between adjacent non-zero pilots Separating the interference from the non-zero pilot by less than the first threshold; receiving the second type of pilot sequence on the second type of symbols, any two adjacent non-zero pilots of the second type of pilot sequence
  • the two pilot intervals are such that the impact of the interference on the non-zero pilot is less than the first threshold, and the second pilot interval is such that the influence of the at least two interferences relative to each other is less than the second threshold;
  • the sequence estimates an equivalent channel gain or at least two types of interference under estimated radio frequency distortion conditions, including estimating an equivalent channel gain from the first type of pilot sequence. At least two types of interference under radio frequency distortion conditions are estimated based on the second type of pilot sequence.
  • the pilot sequence is generated by concatenating a plurality of basic pilot units, where the basic pilot unit includes a non-zero pilot.
  • the extended length includes an inter-carrier interference ICI extended length and a mirrored interference MTI extended length, where the two types of interference include ICI and MTI.
  • a pilot interval of any two adjacent non-zero pilots in the pilot sequence is greater than or equal to a minimum anti-interference distance of the non-zero pilot,
  • the non-zero pilot minimum anti-interference distance is determined according to an extended length of interference under the radio frequency distortion condition.
  • a fourth aspect provides an apparatus for transmitting a pilot signal, the apparatus for performing the method of any of the first aspect or the first aspect of the first aspect.
  • the device can include a processing module and a transmitting module.
  • a fifth aspect provides an apparatus for transmitting a pilot signal, the apparatus comprising a processor, a transceiver, and a memory for performing the first aspect and its corresponding implementation, and the devices of the apparatus of the fifth aspect are The corresponding modules of the four aspects correspond to the corresponding modules.
  • 1 is a schematic diagram of a pilot sequence design.
  • 2 is a schematic diagram of another pilot sequence design.
  • FIG. 3 is a schematic diagram of another pilot sequence design.
  • FIG. 5 and FIG. 6 are schematic diagrams of a pilot sequence design scheme according to an embodiment of the present application.
  • FIG. 7 is a schematic flowchart of a method for transmitting a pilot signal according to an embodiment of the present application.
  • FIG. 8 , FIG. 9 and FIG. 10 are schematic diagrams showing the design idea of the first set of design schemes of the embodiments of the present application.
  • FIG. 11 and FIG. 12 are schematic diagrams showing the design concepts of the second group design and the third group design of the embodiment of the present application.
  • FIG. 13 is a schematic diagram of the effect of RFD on each subcarrier under the pilot sequence design of the embodiment of the present application.
  • FIG. 14 is a schematic diagram of a pilot sequence design of an embodiment of the present application.
  • 15 is a schematic diagram of a pilot sequence design of another embodiment of the present application.
  • 16 is a schematic diagram of a pilot sequence design of another embodiment of the present application.
  • 17 is a schematic diagram of a pilot sequence design of another embodiment of the present application.
  • 18 is a schematic diagram of a pilot sequence design of another embodiment of the present application.
  • 19 is a schematic diagram of a pilot sequence design of another embodiment of the present application.
  • 20 is a schematic diagram of a pilot sequence design of another embodiment of the present application.
  • 21 is a schematic diagram of a pilot sequence design of another embodiment of the present application.
  • 22 is a schematic diagram of a pilot sequence design of another embodiment of the present application.
  • 23 is a schematic diagram of a pilot sequence design of another embodiment of the present application.
  • 24 is a schematic diagram of a pilot sequence design of another embodiment of the present application.
  • 25 is a schematic diagram of a pilot sequence design of another embodiment of the present application.
  • 26 is a schematic diagram of a pilot sequence design of another embodiment of the present application.
  • 27 is a schematic diagram of a pilot sequence design of another embodiment of the present application.
  • 28 is a schematic diagram of a pilot sequence design of another embodiment of the present application.
  • 29 is a schematic block diagram of an OFDM system to which one embodiment of the present application is applied.
  • Figure 30 is a graph of bit error rate for a system to which an embodiment of the present application is applied.
  • FIG. 31 is a schematic block diagram of a transmission pilot signal device according to an embodiment of the present application.
  • 32 is a schematic block diagram of a transmission pilot signal device according to another embodiment of the present application.
  • the pilot signal also referred to as a pilot sequence in the embodiment of the present application, includes a non-zero pilot and a zero pilot (also known as a null pilot). Pilot sequences are commonly used for channel estimation and Radio Frequency Distortion compensation in communication systems. The characteristics of the channel and RF distortion depend on factors such as the environment, frequency range, system settings, and transceiver implementation errors. Therefore, the design of pilot sequences under different conditions is also different. In addition, when pilot signals are transmitted in the frequency domain or transmitted in the time domain, their design is also different. The embodiment of the present application discusses the case of transmitting a pilot signal on a frequency domain.
  • the pilot signals in the frequency domain are mainly applied to a multi-carrier system such as an Orthogonal Frequency Division Multiplexing (OFDM) system or a Single-Carrier Frequency-Division Multiple Access (SC-FDMA) system. And Discrete Fourier Transform-Precoded OFDM (DFT-precoded OFDM) system and the like.
  • the pilot signal can be used to estimate the channel and estimate interference of radio frequency distortion, such as phase noise, frequency offset, and in-phase and quadrature-phase Imbalance (IQI).
  • the pilot signal can also be used in other multi-carrier systems with the same equivalent channel signal model, such as Universal Filtered Multi-Carrier (UFMC) system, Generalized Frequency Division Multiplexing (GFDM). And single carrier frequency domain equalization system.
  • OFDM Orthogonal Frequency Division Multiplexing
  • SC-FDMA Single-Carrier Frequency-Division Multiple Access
  • IQI Discrete Fourier Transform-Precoded OFDM
  • the pilot signal can
  • the design scheme of the existing pilot sequence is mainly divided into the design of the pilot sequence without radio frequency distortion and the pilot sequence design under the condition of radio frequency distortion. Since radio frequency distortion generally exists in an actual system, the embodiment of the present application is applied to pilot sequence design under radio frequency distortion conditions.
  • the existing pilot sequence design under RF distortion conditions mainly includes pilot sequence design for channel + IQI, pilot sequence design for channel + phase noise, and pilot sequence design for channel + phase noise + frequency offset. and many more.
  • the pilot sequence design for Inter-Carrier/Inter-sub-Carrier Interference (ICI) caused by phase noise and Mirror Tone Interference (MTI) caused by IQI is less.
  • Figure 1 shows a prior art pilot sequence design.
  • the scheme does not consider the effects of MTI and ICI on the pilot sequence.
  • ICI adjacent subcarriers
  • MTI image interference
  • Both the non-zero pilot and the zero pilot in the pilot sequence are greatly interfered, resulting in an inaccurate estimation of the equivalent channel gain, which makes the system unable to work properly under the existing pilot design scheme.
  • DC Direct Current
  • Figure 2 shows another prior art pilot sequence design. This scheme does not consider the impact of ICI on the pilot sequence. As shown in the figure, when the RFD level is high, the non-zero pilot and zero pilot in the pilot sequence are greatly disturbed. The system does not work properly under the existing pilot design scheme.
  • FIG. 3 shows another prior art pilot sequence design.
  • the scheme does not consider the effects of MTI and ICI on the pilot sequence.
  • the received pilot is corrupted by the ICI of the data and the MTI of the other pilots, resulting in inaccurate channel estimation and degraded data demodulation performance.
  • the existing pilot sequence design scheme only considers image interference (MTI), or only considers inter-carrier interference (ICI), or the effects of MTI and ICI are not considered. Therefore, when the RFD level is high, ICI and/or MTI will seriously affect the performance of the system, making the system not working properly under the existing pilot design scheme.
  • MTI image interference
  • ICI inter-carrier interference
  • the embodiments of the present application propose a new effective pilot sequence design scheme for the above deficiencies of the existing solutions.
  • the design of the pilot sequences in the embodiments of the present application can be divided into two types.
  • the first type of pilot sequence as shown in FIG. 4, all the useful subcarriers of the OFDM symbol in which the pilot sequence is located are used to transmit pilots (including non-zero pilots or zero pilots).
  • the OFDM symbol in which the first type of pilot sequence is located is placed at the top of the transmitted frame, or inserted in the middle of the transmitted frame, or interspersed throughout the transmitted frame.
  • the second type of pilot sequence as shown in Figure 5, simultaneously transmits data and pilots (including non-zero pilots or zero pilots) within the same OFDM symbol.
  • the first type of pilot sequence and the second type of pilot sequence can also be designed together.
  • the subcarriers of the OFDM are numbered, and the index 0 corresponds to the DC subcarrier.
  • the subcarrier index on the side lower than the DC subcarrier frequency is negative, and the subcarrier index on the side higher than the DC subcarrier frequency is positive.
  • Subcarrier spacing is ⁇ f
  • the index sets of the nth OFDM symbol on the left and right sides of the DC subcarrier are respectively non-zero pilots.
  • the normalized equivalent channel coherence bandwidth is which is Subcarriers, where Indicates rounding up.
  • W coh represents the coherence bandwidth of the channel; for frequency domain related IQI systems, W coh represents the coherent bandwidth of the equivalent channel (channel + frequency domain coherent IQI).
  • the channel can be considered to remain substantially unchanged.
  • the extended length refers to the range of influence in the frequency domain due to interference spreading.
  • subcarriers within the extended length range can cause interference to non-zero pilots.
  • Non-zero pilots are subject to interference by all subcarriers alongside, for example, for ICI, the closer the subcarriers are to non-zero pilots, the greater the interference to non-zero pilots.
  • the ICI extension length refers to the range of influence in the frequency domain due to ICI expansion, such as the number of subcarriers affected in the frequency domain due to ICI expansion.
  • the MTI extension length refers to the range of influence in the frequency domain due to the MTI extension, such as the number of subcarriers affected in the frequency domain due to the MTI extension.
  • the extension of the interference is not limited to the number of subcarriers, and may be used as a unit in other manners.
  • FIG. 7 shows a schematic flowchart of a method for transmitting a pilot signal according to an embodiment of the present application, which may be performed by a transmitting device. As shown in FIG. 7, the method includes:
  • the pilot sequence is generated according to the pilot interval, where a pilot between any two adjacent non-zero pilots in the pilot sequence is a zero pilot, and the pilot sequence is non-zero-guided.
  • the mirrored subcarrier corresponding to the frequency subcarrier is an empty subcarrier;
  • the transmitting device generates a pilot sequence, where pilot intervals of any two adjacent non-zero pilots in the pilot sequence are determined according to an extended length of interference under radio frequency distortion conditions, the pilot sequence
  • the pilot between any two adjacent non-zero pilots is a zero pilot, and the mirror subcarrier corresponding to the subcarrier of the non-zero pilot is a null subcarrier; the pilot sequence is transmitted.
  • the method may include: determining a pilot interval of any two adjacent non-zero pilots in the pilot sequence, the pilot interval being greater than or equal to 1; generating the guide according to the pilot interval a frequency sequence, where pilots between any two adjacent non-zero pilots in the pilot sequence are zero pilots, and a mirror subcarrier corresponding to a non-zero pilot subcarrier of the pilot sequence is a null subcarrier Sending the pilot sequence.
  • the method may include: generating a pilot sequence, where a pilot interval of any two adjacent non-zero pilots in the pilot sequence is greater than or equal to 1, and any two adjacent non-contiguous pilot sequences
  • the pilot between the zero pilots is a zero pilot, and the mirror subcarrier corresponding to the subcarrier of the non-zero pilot is a null subcarrier; the pilot sequence is transmitted.
  • the system when the system allocates a non-zero pilot carrier, the system also allocates a zero pilot carrier.
  • the pilot spacing design of non-zero pilots is based on the principle of non-interference, which significantly reduces the influence of non-zero pilot carriers and data interference, which makes the system less affected by RF distortion and improves system performance.
  • the interferences discussed in the embodiments of the present application mainly relate to ICI and MTI.
  • the influence on the pilot sequence design can be taken into account in consideration of similar ICI and MTI.
  • the extended length includes an inter-carrier interference ICI extension length and a mirror interference MTI extension length.
  • the ICI extension length can also be referred to as an ICI spreading factor, which in turn can be referred to as an MTI spreading factor.
  • the ICI expansion factor and the MTI extension factor may be unilateral or bilateral, and different configurations may be selected according to different criteria, which is not limited in this embodiment of the present application.
  • the simultaneous consideration of phase noise causes ICI and IQI to cause the influence of MTI.
  • the embodiments of the present application are mainly directed to a system in which both the transmitting device and the receiving device have high radio frequency distortion, and the radio frequency distortion of each RF channel causes non-coherent ICI and MTI.
  • S501 determines a pilot interval of any two adjacent non-zero pilots in the pilot sequence, and may include:
  • a pilot interval of any two adjacent non-zero pilots in the pilot sequence is greater than or equal to a minimum of the non-zero pilot Anti-interference distance.
  • the extended length of the interference under the condition of radio frequency distortion can be obtained before this.
  • the ICI and MTI interferences are used to obtain the inter-carrier interference ICI extension length and the image interference MTI extension length under the condition of radio frequency distortion.
  • the process of transmitting a pilot sequence can be as follows:
  • the pilot sequence is transmitted.
  • the design parameters of the pilot sequence are also different according to the level of the RFD, the channel setting, or the system setting.
  • the embodiment of the present application is directed to a pilot sequence design scheme for an OFDM, SC-FDMA, or other multi-carrier system having a frequency domain selective channel, a transmitting device, and/or a receiving device having an RFD, including: a method for estimating an equivalent channel gain.
  • a design scheme of a pilot sequence a design scheme of a pilot sequence for estimating an I CI coefficient and an MTI coefficient
  • a design scheme of a pilot sequence for estimating an equivalent channel gain and estimating an ICI coefficient and an MTI coefficient are examples of a pilot sequence design scheme for an OFDM, SC-FDMA, or other multi-carrier system having a frequency domain selective channel, a transmitting device, and/or a receiving device having an RFD, including: a method for estimating an equivalent channel gain.
  • a design scheme of a pilot sequence a design scheme of a pilot sequence for estimating an I CI
  • the method may include: acquiring an inter-carrier interference ICI extension length and a picture interference MTI extension length under radio frequency distortion conditions; determining a non-zero pilot minimum anti-interference distance according to the ICI extension length and the MTI extension length Generating a pilot sequence according to the non-zero pilot minimum anti-interference distance, where a pilot interval of any two adjacent non-zero pilots in the pilot sequence is greater than or equal to the non-zero pilot minimum impedance Interference distance, the pilot between any two adjacent non-zero pilots in the pilot sequence is zero pilot, and the mirror corresponding to the subcarrier of the non-zero pilot
  • the subcarrier is an empty subcarrier; the pilot sequence is transmitted.
  • the method for transmitting a pilot signal in the embodiment of the present application is different from the existing pilot sequence design in that a non-zero pilot carrier is allocated to the system, and a zero pilot carrier is also allocated to the system, and a non-zero pilot is allocated.
  • the pilot spacing design is based on the principle of non-interference, so that the non-zero pilot carrier and data are significantly weakened by the influence of MTI and ICI, so that the system is less affected by RFD and improves the performance of the system.
  • the two types of pilot sequences involved in the embodiments of the present application have been described above.
  • the design scheme of the pilot sequence of the embodiment of the present application can be divided into four groups.
  • the first set of design schemes is to use the first type of pilot sequence to estimate the equivalent channel gain;
  • the second set of design schemes is to use the second type of pilot sequence to estimate the ICI coefficient and the MTI coefficient;
  • the fourth set of design schemes is to combine the first set of design schemes with the second set of design schemes for estimating the equivalent
  • the channel gain and estimated ICI coefficients and MTI coefficients are the design of the pilot type of the hybrid type.
  • DC subcarrier may not be used in the embodiment of the present application, which is indicated by a broken line in the figure.
  • Figures 8, 9 and 10 show a first set of designs for estimating the equivalent channel gain, the pilot sequence covering the entire effective subcarrier range.
  • the pilot interval is such that the impact of the interference on the non-zero pilot is less than the first threshold
  • the generating the pilot sequence includes: generating the pilot sequence according to an equivalent channel coherence bandwidth of the system.
  • the set of design schemes for estimating the equivalent channel gain is designed such that the pilot sequence of the pilot sequence is equivalent to the interference interval, so that the influence of the interference on the non-zero pilot is less than the first threshold, and the pilot sequence is ultimately equivalent.
  • the pilot spacing is less than or equal to the equivalent channel coherence bandwidth of the system.
  • the first threshold may be determined based on the degree of tolerance of the system to interference.
  • the pilot interval can be designed by referring to the extended length of the interference existing in the system so that the interference to the non-zero pilot has less than the first threshold.
  • each subcarrier is subject to inter-carrier interference (ICI) of surrounding subcarriers and image interference (MTI) of the mirrored location. Therefore, in order to make non-zero pilots unaffected by ICI and MTI extension, insert an appropriate number of zero pilots between non-zero pilots, that is, pilot intervals between non-zero pilots obtained by inserting zero pilots.
  • the effect on non-zero pilots is less than a certain threshold, such as the first threshold.
  • the transmitting device separately transmits a non-zero pilot signal on multiple pilot subcarriers, and at least one empty subcarrier between any two adjacent non-zero pilot subcarriers, and the null subcarrier does not send a signal.
  • the mirror subcarrier of the non-zero pilot position is also an empty subcarrier.
  • the subcarriers adjacent to each other on the left and right of the mirror subcarrier corresponding to the subcarriers of the non-zero pilot are also null subcarriers (as shown in FIG. 9 and FIG. 10). Thereby, the influence of MTI on system performance can be further reduced.
  • Max( ⁇ +1, 2 ⁇ +2) is called the minimum anti-interference distance for estimating the equivalent channel gain non-zero pilot, and may also be referred to as the first non-zero pilot minimum anti-interference distance, which is represented by IFD main .
  • IFD main max( ⁇ +1,2 ⁇ +2) is an optional implementation.
  • the mirror subcarriers occupy one subcarrier.
  • the MTI has a unilateral extension length of ⁇ and a bilateral extension length of 2 ⁇ .
  • the number of null carriers required is 2 ⁇ +1, and the pilot spacing of non-zero pilots needs to be greater than or equal to 2 ⁇ +2 from the MTI perspective.
  • the subcarriers of the non-zero pilot subcarriers are respectively adjacent to the left and right subcarriers of the mirror subcarriers.
  • the wave can also be an empty subcarrier.
  • Non-zero pilot minimum anti-interference distance which can include:
  • Equivalent channel coherence bandwidth according to the system And a first non-zero pilot minimum anti-interference distance IFD main , which can generate a pilot sequence. If the pilot interval of the non-zero pilot is less than or equal to the equivalent channel coherence bandwidth, since the channel is substantially unchanged within the channel coherence bandwidth, the channel estimation requirement can be satisfied by one symbol. Otherwise, multiple pilot symbols are needed for joint estimation such that the combined adjacent non-zero pilot spacing is less than or equal to the equivalent channel coherence bandwidth.
  • 11 and 12 show a second set of designs and a third set of designs for estimating ICI coefficients and MTI coefficients, or for estimating equivalent channel gains and estimating ICI coefficients and MTI coefficients.
  • 2 ⁇ +2 ⁇ +1 zero pilots can be inserted between non-zero pilots such that ICI and MTI of non-zero pilots are attenuated and are not affected by ICI and MTI extension.
  • 2 ⁇ +2 ⁇ +2 is called the non-zero pilot minimum anti-interference distance against ICI and MTI, and can also be called the second non-zero pilot minimum anti-interference distance, expressed by IFD ICI, MTI .
  • the difference between the second set of design schemes and the third set of design schemes is that the selection of pilot intervals in the first set of design schemes only needs to ensure that ICI extension and MTI extension do not interfere with non-zero pilots, ICI and MTI. May coincide.
  • the principle of selection of pilot spacing in the second set of design schemes and the third set of design schemes also needs to satisfy the mutual interference between ICI extension and MTI extension. Accurately estimate ICI and MTI.
  • the pilot intervals of the non-zero pilots of the second set of design schemes and the third set of design schemes are larger than the second set of design schemes and the first Three sets of design options.
  • the pilot interval of the non-zero pilot of the second set of design schemes and the third set of design schemes is greater than or equal to the second set of design schemes and the Three sets of design options.
  • the pilot sequence is configured to estimate at least two types of interference in a radio frequency distortion condition, the pilot interval causing the influence of the at least two types of interference on a non-zero pilot to be less than a first threshold, and the pilot
  • the spacing is such that the effects of the at least two disturbances are less than a second threshold.
  • the second threshold may be determined based on the degree of tolerance of the system to interference.
  • the pilot interval can be designed by referring to the extended length of the interference existing in the system so that the interference between the interferences is less than the second threshold.
  • the second set of designs differs from the third set of designs in that the second set of designs is used to estimate the ICI coefficients and the MTI coefficients, and the third set of designs is used to estimate the equivalent channel gain and estimate the ICI coefficients and MTI coefficients.
  • the data signal is also transmitted on the symbol transmitting the pilot sequence. Accordingly, transmitting the pilot sequence can include transmitting the pilot sequence on a symbol; the method 500 further comprising: transmitting a data signal on the symbol.
  • the second set of design schemes and the third set of design schemes may include:
  • FIG. 13 is a diagram showing the effect of RFD on each subcarrier under the pilot sequence design (design of FIG. 11) of the embodiment of the present application.
  • the non-zero pilot is basically unaffected by the ICI and MTI from other pilots, so that it can be used to estimate the equivalent channel gain; the zero pilot is used to transmit ICI and MTI information, so that Used to estimate ICI coefficients and MTI coefficients.
  • the fourth set of designs can combine the first set of designs with the second set of designs.
  • the pilot sequence includes a first type of pilot sequence and a second type of pilot sequence, where the first type of pilot sequence is used to estimate an equivalent channel gain, and any two of the first type of pilot sequences.
  • the pilot intervals of the adjacent non-zero pilots are the first pilot intervals, and the second type of pilot sequences are used to estimate at least two types of interference in the radio frequency distortion condition, and any of the second type of pilot sequences
  • the pilot interval of two adjacent non-zero pilots is a second pilot interval, and the generating the pilot sequence according to the pilot interval includes:
  • the first type of pilot sequence being generated according to the first pilot interval and an equivalent channel coherence bandwidth of the system, the first pilot interval causing interference to non-zero pilots The impact is less than the first threshold;
  • the second type of pilot sequence is generated according to the second pilot interval, and the second of any two adjacent non-zero pilots in the second type of pilot sequence
  • the pilot interval is such that the influence of the interference on the non-zero pilot is less than the first threshold
  • the second pilot interval is such that the influence of the at least two interferences relative to each other is less than the second threshold
  • the transmitting the pilot sequence includes:
  • the second type of pilot sequence is transmitted on a second type of symbol.
  • the pilot sequence includes a first type of pilot sequence and a second type of pilot sequence
  • the first type of pilot sequence is used to estimate an equivalent channel gain
  • the first type of pilot a pilot interval of any two adjacent non-zero pilots in the sequence is a first pilot interval
  • the second type of pilot sequence is used to estimate at least two types of interference in a radio frequency distortion condition
  • the second type of pilot The pilot interval of any two adjacent non-zero pilots in the frequency sequence is a second pilot interval
  • the generating the pilot sequence according to the pilot interval includes: generating the first type of pilot sequence
  • the first type of pilot sequence is generated according to an equivalent channel coherence bandwidth of the system, the first pilot interval is such that the interference of the interference to the non-zero pilot is smaller than the first threshold; and the second type of pilot sequence is generated.
  • the second pilot interval of any two adjacent non-zero pilots in the second type of pilot sequence causes interference to have a lesser impact on the non-zero pilot than the first threshold, and the second pilot interval causes the At least two interferences have an influence on each other that is less than a second threshold; Pilot sequence, comprising: a first type in the first type symbol transmitted pilot sequence; second type symbol on the second transmit pilot type sequence.
  • the pilot sequence is used to estimate an equivalent channel gain, and is used to estimate ICI and MTI, the ICI extension length is ⁇ subcarriers, and the MTI extension length is ⁇ subcarriers, according to the ICI extension length and
  • the MTI extended length, determining a non-zero pilot minimum anti-interference distance may include:
  • pilot sequences there may be multiple types of pilot sequences formed, one of which is a pilot sequence generated by a plurality of basic pilot units, and the basic pilot unit includes a non-zero pilot. . This is illustrated in the examples below.
  • the first set of designs can be divided into the following scenarios in detail.
  • One of the scenarios is that the system has a single digital channel, and generating a pilot sequence according to the minimum anti-interference distance of the non-zero pilot may include: if the first non-zero pilot minimum anti-interference distance IFD main is less than or equal to The effective channel coherent bandwidth, the pilot sequence is generated on one symbol, and the pilot spacing of any two adjacent non-zero pilots in the pilot sequence is less than or equal to the equivalent channel coherence bandwidth and greater than Or equal to the first non-zero pilot minimum anti-interference distance.
  • embodiments of the present application are directed to systems having a single digital channel (ie, only one digital to analog convert (DAC) and analog to digital convert (ADC) channel).
  • the normalized equivalent channel coherence bandwidth is
  • a pilot sequence is generated on one symbol, and the non-zero pilot index set can be expressed as:
  • the set of non-zero pilots on the left and right sides of the DC subcarrier are respectively with
  • the DC subcarriers are not used and the DC subcarriers are indicated by dashed lines in the figure.
  • the non-zero pilot is separate from the extension of the ICI and the extension of the MTI.
  • the non-zero pilots are equally spaced over the effective frequency band, and the pilot spacing of any two adjacent non-zero pilots is not greater than the equivalent channel coherence bandwidth, ensuring frequency domain selective channel gain. Estimated reliability.
  • the pilot interval of any two adjacent non-zero pilots in the pilot sequence may be greater than or equal to the first non-zero pilot minimum anti-interference distance IFD main , and the non-zero pilot is not required to be on the effective frequency band. They are equally spaced.
  • the DC subcarriers are not used, and are indicated by a broken line in the figure, but the embodiment of the present application does not limit whether to use the DC subcarrier, and no further description is provided herein.
  • generating a pilot sequence according to the non-zero pilot minimum anti-interference distance may include: if the first non-zero pilot minimum anti-interference distance IFD main is greater than the Equivalent channel coherence bandwidth, M pilot sequences are generated on M symbols, and pilot intervals of any two adjacent non-zero pilots in the pilot sequence are greater than or equal to the first non-zero pilot The minimum anti-interference distance, the subcarriers corresponding to the non-zero pilots of any two of the M pilot sequences are different, wherein M is rounded to the IFD main / equivalent channel coherence bandwidth.
  • embodiments of the present application are directed to systems having a single digital channel.
  • the normalized equivalent channel coherence bandwidth is
  • the digital channel needs to generate and transmit a pilot sequence on consecutive M symbols, where M is rounded to the IFD main / equivalent channel coherence bandwidth, ie
  • the set of non-zero pilot indices of the mth pilot OFDM symbol can be expressed as:
  • the system has K digital channels, where K is greater than or equal to 2, and generating a pilot sequence according to the non-zero pilot minimum anti-interference distance may include: if the first non-zero pilot The K times of the minimum anti-interference distance IFD main is less than or equal to the equivalent channel coherence bandwidth, and K pilot sequences are generated on one symbol, and any two adjacent ones of the pilot sequences in the K pilot sequences The pilot interval of the non-zero pilot is less than or equal to the equivalent channel coherence bandwidth, and is greater than or equal to the first non-zero pilot minimum anti-interference distance, any two pilots of the K pilot sequences The subcarriers corresponding to the non-zero pilots of the sequence are different.
  • embodiments of the present application are directed to systems having K digital channels.
  • the normalized equivalent channel coherence bandwidth is
  • a pilot sequence is generated and transmitted on one symbol.
  • the design of the pilot sequence on this symbol can be similar to the design in the example of Figure 14.
  • the set of non-zero pilot indices of the pilot OFDM symbol can be expressed as:
  • the two digital channels use the same symbol to transmit the pilot sequence. For clarity of expression, the two digital channels will be shown separately.
  • the set of non-zero pilots on the left and right sides of the DC subcarrier are with
  • the set of non-zero pilots on the left and right sides of the DC subcarrier are with
  • the non-zero pilot is separate from the ICI extension and the MTI extension.
  • the non-zero pilots are equally spaced over the effective frequency band, and the pilot spacing of any two adjacent non-zero pilots is not greater than the equivalent channel coherence bandwidth, ensuring frequency domain selective channel gain. Estimated reliability.
  • the system has K digital channels, where K is greater than or equal to 2, and generating a pilot sequence according to the non-zero pilot minimum anti-interference distance may include: if the first non-zero pilot The K times of the minimum anti-interference distance IFD main is greater than the equivalent channel coherence bandwidth, and the first non-zero pilot minimum anti-interference distance IFD main is less than or equal to the equivalent channel coherence bandwidth, and is generated on N symbols K pilot sequences, where N is less than or equal to K, and k n pilot sequences are generated on the nth symbol, and the values of n are 1, 2, ..., N, K n is less than or equal to K 0 , K 0 is a rounding of the equivalent channel coherence bandwidth / IFD main , and the prediction of any two adjacent non-zero pilots in each of the K n pilot sequences on the nth symbol
  • the frequency interval is less than or equal to the equivalent channel coherence bandwidth and greater than or equal to the first non-zero
  • embodiments of the present application are directed to systems having K digital channels. Normalized equivalent channel coherence bandwidth is satisfied
  • K pilot sequences are generated on N symbols.
  • the embodiment of the present application requires N symbols to transmit a pilot sequence, and the symbol n (Sym n) carries a pilot sequence of K n digital channels.
  • a pilot interval of any two adjacent non-zero pilots in each of the K n pilot sequences on the nth symbol is less than or equal to the equivalent channel coherence bandwidth, and is greater than or Equal to the first non-zero pilot minimum anti-interference distance, and the subcarriers corresponding to the non-zero pilots of any two of the K n pilot sequences on the nth symbol are different.
  • a pilot sequence of 2 channels can be carried, wherein the set of non-zero pilots on the left and right sides of the DC subcarrier of the first channel are respectively with The set of non-zero pilots on the left and right sides of the DC subcarrier of the second channel are respectively with
  • a pilot sequence of 2 channels can be carried, wherein the set of non-zero pilots on the left and right sides of the DC subcarrier of the third channel are respectively with The set of non-zero pilots on the left and right sides of the DC subcarrier of the fourth channel are respectively with
  • the system has K digital channels, where K is greater than or equal to 2, and generating a pilot sequence according to the non-zero pilot minimum anti-interference distance may include: if the first non-zero pilot The minimum anti-interference distance IFD main is greater than the equivalent channel coherence bandwidth, and MK pilot sequences are generated on MK symbols, and each digital channel generates M pilot sequences on M symbols, where M is the pair IFD main /the equivalent channel coherent bandwidth is rounded, the pilot interval of any two adjacent non-zero pilots in each pilot sequence is greater than or equal to the first non-zero pilot minimum anti-interference distance, each digital channel The subcarriers corresponding to the non-zero pilots of any two of the M pilot sequences are different.
  • embodiments of the present application are directed to systems having K digital channels. Normalized equivalent channel coherence bandwidth is satisfied
  • each digital channel needs to generate and transmit a pilot sequence on consecutive M symbols, where M is rounded to the IFD main / equivalent channel coherence bandwidth, ie Therefore, K digital channels need to generate MK pilot sequences on MK symbols.
  • the design of each digital channel can be similar to the example of FIG.
  • the set of non-zero pilots on the left and right sides of the DC subcarrier on symbol 1 are with The set of non-zero pilots on the left and right sides of the DC subcarrier on symbol 2 are respectively with
  • the set of non-zero pilots on the left and right of the DC subcarrier on symbol 3 are with The set of non-zero pilots on the left and right sides of the DC subcarrier on symbol 4 are respectively with
  • the second type of pilot sequence is used to estimate the ICI coefficient and the MTI coefficient, and the pilot (including non-zero pilot and null pilot) and data are simultaneously transmitted on one symbol, that is, the pilot is transmitted. On the symbol of the frequency sequence, a data signal is also transmitted.
  • the pilot interval selection principle is to ensure that the ICI extension and the MTI extension do not interfere with the non-zero pilot, while satisfying the mutual interference between the ICI extension and the MTI extension, and therefore need to be non-zero-guided. Insert 2 ⁇ +2 ⁇ +1 null pilots between the frequencies.
  • the pilot sequence may be generated by a basic pilot unit cascaded, where the basic pilot unit includes one non-zero pilot, and when the two basic pilot units are cascaded, two of the foregoing
  • the pilot spacing of the two non-zero pilots in the basic pilot unit is greater than or equal to the second non-zero pilot minimum anti-interference distance.
  • the basic pilot unit may include a greater number of zeros, that is, zero pilot.
  • the embodiment of the present application does not limit the form of the basic pilot unit.
  • a basic pilot unit may be optionally selected in the following description, which is described by the symbol p.
  • the second set of design schemes can be divided into the following scenarios in detail.
  • One of the scenarios is that the system has a single digital channel, and generating a pilot sequence according to the minimum anti-interference distance of the non-zero pilot may include: if the pilot sequence The length of the pilot is less than or equal to the pilot available channel bandwidth, and a pilot sequence including V non-zero pilots is generated on the contiguous subcarrier group on the left side of the DC carrier of one symbol and the contiguous subcarrier group on the right side, respectively. And a pilot interval of any two adjacent non-zero pilots in the pilot sequence is greater than or equal to the second non-zero pilot minimum anti-interference distance, where V is greater than 1.
  • the size of V can be determined based on the available channel bandwidth of the pilot on the symbol. The larger V, the more accurate the estimate of interference.
  • p R and p L can be placed on any two consecutive subcarrier groups that satisfy the above conditions. If the leftmost or rightmost null pilot 0 1 ⁇ is connected to the null subcarrier next to the sideband null subcarrier or the DC subcarrier, the null pilot 0 1 ⁇ may be omitted.
  • the system has K digital channels, where K is greater than or equal to 2, and the generating a pilot sequence according to the non-zero pilot minimum anti-interference distance may include: if the K digital channels are guided The total length of the frequency sequence is less than or equal to the pilot available channel bandwidth on one symbol, and K pilot sequences are generated on one symbol, and any two adjacent non-zeros in each of the K pilot sequences The pilot interval of the pilot is greater than or equal to the second non-zero pilot minimum anti-interference distance, and the subcarriers corresponding to the non-zero pilots of any two of the K pilot sequences are different.
  • p represents any of the two basic pilot units.
  • the pilot vector ⁇ p R,(k) ⁇ may be a cascade of [p R,(1) , p R,(2) ,...,p R,(K) ], or may be added with several spaces.
  • the concatenation of carriers eg, a null subcarrier
  • carriers eg, a null subcarrier
  • the non-zero pilot index set has the following correlation: (in the case where the basic pilot unit is directly cascaded), or (In the case of adding an empty subcarrier between basic pilot units).
  • the set of non-zero pilots to the right of the DC subcarrier is denoted by p R and can be derived from Obtain
  • the non-zero pilot set to the left of the DC subcarrier is denoted by p L and can be obtained from Obtain.
  • n denotes the symbol n, and only one symbol is occupied in the embodiment of the present application, and n at the lower corner can be omitted.
  • the null pilot 0 1 ⁇ may be omitted.
  • the two digital channels use the same pilot symbols in time.
  • the set of non-zero pilots to the left of the DC subcarrier is The set of locations occupied by the basic pilot unit is The set of non-zero pilots to the right of the DC subcarrier is The set of locations occupied by the basic pilot unit is
  • the set of non-zero pilots to the left of the DC subcarrier is The set of locations occupied by the basic pilot unit is The set of non-zero pilots to the right of the DC subcarrier is The set of locations occupied by the basic pilot unit is This design allows non-zero pilot and ICI expansion and MTI extension to be attenuated, ensuring that data and pilots are not interfered with by ICI and MTI.
  • the set of non-zero pilots to the left of the DC subcarrier is The set of locations occupied by the basic pilot unit is p L, (2) ; the set of non-zero pilots to the right of the DC subcarrier is The set of locations occupied by the basic pilot unit is p R, (2) .
  • the set of non-zero pilots to the left of the DC subcarrier is The set of locations occupied by the basic pilot unit is p L, (3) ; the set of non-zero pilots to the right of the DC subcarrier is The set of locations occupied by the basic pilot unit is p R, (3) .
  • This design allows non-zero pilot and ICI expansion and MTI extension to be attenuated, ensuring that data and pilots are not interfered with by ICI and MTI.
  • the system has K digital channels, where K is greater than or equal to 2, and the generating a pilot sequence according to the non-zero pilot minimum anti-interference distance may include: if the K digital channels are guided The total length of the frequency sequence is greater than the pilot available channel bandwidth on one symbol, and K pilot sequences are generated on T symbols, where T is less than or equal to K, and the pilot of the t-th symbol can generate K t over the available channel bandwidth.
  • the pilot sequence where t has a value of 1, 2, ..., T, K t is less than or equal to K' 0 , a symbol can transmit a pilot sequence of up to K' 0 digital channels, the K pilots a pilot interval of any two adjacent non-zero pilots in each pilot sequence in the sequence is greater than or equal to the second non-zero pilot minimum anti-interference distance, and K t guides on the t-th symbol
  • the subcarriers corresponding to the non-zero pilots of any two pilot sequences in the frequency sequence are different.
  • the design of the pilot sequence for each digital channel on the symbol is as shown in Fig. 22.
  • the pilot sequence of the first digital channel is designed on symbol 1, and the set of non-zero pilots on the left side of the DC subcarrier is The set of locations occupied by the basic pilot unit is The set of non-zero pilots to the right of the DC subcarrier is The set of locations occupied by the basic pilot unit is Designing a pilot sequence for the second digital channel on symbol 1, the set of non-zero pilots to the left of the DC subcarrier is The set of locations occupied by the basic pilot unit is The set of non-zero pilots to the right of the DC subcarrier is The set of locations occupied by the basic pilot unit is Designing a pilot sequence for the third digital channel on symbol 2, the set of non-zero pilots to the left of the DC subcarrier is The set of locations occupied by the basic pilot unit is The set of non-zero pilots to the right of the DC subcarrier is The set of locations occupied by the basic pilot unit is Designing the pilot sequence of the fourth digital channel on symbol 2, the set of non-zero pilots on the left
  • the first type of pilot sequence is used to estimate the equivalent channel gain and estimate the ICI coefficient and the MTI coefficient, and the pilot (including non-zero pilot and null pilot) covers the entire effective subcarrier range.
  • the pilot interval selection principle is to ensure that the ICI extension and the MTI extension do not interfere with the non-zero pilot, and that the ICI extension and the MTI extension do not interfere with each other, so it is necessary to insert 2 ⁇ +2 ⁇ +1 spaces between the non-zero pilots. Pilots, such that non-zero pilot ICI and MTI are attenuated and are not affected by ICI expansion and MTI expansion.
  • the transmitting device separately transmits a non-zero pilot signal on multiple subcarriers, and at least one empty subcarrier between any two adjacent non-zero pilot subcarriers, the null subcarrier does not transmit a signal, and is not a zero pilot.
  • the mirror subcarrier corresponding to the frequency subcarrier is also an empty subcarrier.
  • pilot spacing between non-zero pilots is less than or equal to the coherent bandwidth of the equivalent channel, since the channel is substantially unchanged within the channel coherence bandwidth, the channel estimation requirement can be satisfied by one symbol. Otherwise, multiple symbols are needed for joint estimation such that the combined adjacent non-zero pilot spacing is less than or equal to the coherence bandwidth of the equivalent channel.
  • the third set of design schemes can be completely similar to the first set of design schemes, except that the first non-zero pilot minimum anti-interference distance IFD main in the first set of design schemes uses the second non-zero pilot minimum anti-interference distance. IFD ICI, MTI instead.
  • a system having a single digital channel the generating a pilot sequence according to the non-zero pilot minimum anti-interference distance, including:
  • the MTI is less than or equal to the equivalent channel coherence bandwidth, generating the pilot sequence on one symbol, any two adjacent ones of the pilot sequences
  • the pilot interval of the non-zero pilot is less than or equal to the equivalent channel coherence bandwidth and greater than or equal to the second non-zero pilot minimum anti-interference distance;
  • the MTI is greater than the equivalent channel coherence bandwidth, respectively generate U pilot sequences on the U symbols, and any two of the U pilot sequences
  • the subcarriers corresponding to the non-zero pilots of the pilot sequences are different, and the pilot spacing of any two adjacent non-zero pilots in each of the U pilot sequences is greater than or equal to the pilot interval.
  • the embodiment of the present application normalizes the equivalent channel coherence bandwidth for a single digital channel system.
  • IFD ICI, MTI 2 ( ⁇ + ⁇ +1)
  • the ICI coefficient and the MTI coefficient are time-invariant or time-varying scenarios.
  • the pilot design needs to meet This design can be designed using the basic pilot unit p (including the basic pilot unit-p 1 or the basic pilot unit 2 p 2 ).
  • p can be repeated from the l 1 (or l 1 -1) subcarriers until the last valid subcarrier N R .
  • the left guide DC subcarrier frequency design can be repeated from the first p -l 1 + ⁇ subcarrier, until the last active subcarriers -N L.
  • any unused subcarriers are treated as empty subcarriers.
  • the set of non-zero pilots on the left and right sides of the DC subcarrier are respectively with
  • the specific method is to generate a pilot sequence according to the non-zero pilot minimum anti-interference distance, including: generating a first type of pilot sequence on the first type of symbol, any two of the first type of pilot sequence a pilot interval of the adjacent non-zero pilot is greater than or equal to the first non-zero pilot minimum anti-interference distance; generating a first symbol on the second type of symbol after the first type of symbol And a second type of pilot sequence, where a pilot interval of any two adjacent non-zero pilots in the second type of pilot sequence is greater than or equal to the second non-zero pilot minimum anti-interference distance.
  • the first non-zero pilot minimum anti-interference distance IFD main is less than or equal to the equivalent channel coherence bandwidth, generate a first type of pilot sequence on a first type of symbol, the first type of pilot a pilot interval of any two adjacent non-zero pilots in the sequence is greater than or equal to the first non-zero pilot minimum anti-interference distance, and less than or equal to the equivalent channel coherence bandwidth;
  • any of the first type of pilot sequences a pilot interval of two adjacent non-zero pilots greater than or equal to the first non-zero pilot minimum anti-interference distance, any two of the Y first-class pilot sequences
  • the subcarriers corresponding to the non-zero pilots are different, wherein Y is rounded up on the coherent bandwidth of the IFD main / equivalent channel;
  • the design of the present application may be different when applied to scenes of ICI and MTI that are time-invariant or slow-changing, and scenes of ICI and MTI that change instantly.
  • the difference in pilot sequence design in both scenarios is the number of symbols in the transmission frame that transmit the second type of pilot sequence.
  • the symbols transmitting the first type of pilot sequence need only one symbol for transmitting the second type of pilot sequence; and for the scenes of ICI and MTI that change instantly, ie symbols
  • each symbol following the symbol transmitting the first type of pilot sequence needs to be set to transmit the symbol of the second type of pilot sequence.
  • the second symbol (symbol 2) is a symbol for transmitting a second type of pilot sequence based on an example design similar to that of FIG.
  • a scenario of the third set of designs is that the system has K digital channels, where K is greater than or equal to 2, and the generating a pilot sequence according to the non-zero pilot minimum anti-interference distance may include: a second non-zero pilot minimum anti-interference distance IFD ICI, K times the MTI being less than or equal to the equivalent channel coherence bandwidth, generating K pilot sequences on one symbol, each pilot of the K pilot sequences a pilot interval of any two adjacent non-zero pilots in the sequence is less than or equal to the equivalent channel coherence bandwidth, and greater than or equal to the second non-zero pilot minimum anti-interference distance, the K pilots The subcarriers corresponding to the non-zero pilots of any two pilot sequences in the sequence are different.
  • Embodiments of the present application normalize equivalent channel coherence bandwidth for systems with K digital channels
  • the ICI coefficient and the MTI coefficient are scenes that are time-invariant or slow-changing.
  • Different digital channels transmit pilot sequences on the same symbol and are distinguished by frequency division, that is, the subcarriers corresponding to the non-zero pilots of any two pilot sequences in the K pilot sequences are different, and each digital channel A similar single digital channel design is used in Figure 24.
  • the two digital channels use the same symbol to transmit pilots separately. It can be found that non-zero pilot and ICI extension and MTI extension are weakened, non-zero pilots will not be affected by ICI and MTI, and non-zero pilot spacing IFD ICI, MTI is less than the effective channel coherence bandwidth.
  • the set of non-zero pilots on the left and right sides of the DC subcarrier are with
  • the set of non-zero pilots on the left and right sides of the DC subcarrier are with
  • the system has K digital channels, where K is greater than or equal to 2, and the generating a pilot sequence according to the minimum anti-interference distance of the non-zero pilot may include: The second non-zero pilot minimum anti-interference distance IFD ICI, K times of the MTI is greater than the equivalent channel coherence bandwidth, and the second non-zero pilot minimum anti-interference distance IFD ICI, MTI is less than or equal to the said The effective channel coherence bandwidth, K pilot sequences are generated on W symbols, wherein W is less than or equal to K, K w pilot sequences are generated on the wth symbol, and the value of w is 1, 2, ...
  • W, K w is less than or equal to K" 0
  • K" 0 is the equivalent channel coherence bandwidth / IFD ICI, rounded under MTI
  • each of the K w pilot sequences on the wth symbol a pilot interval of any two adjacent non-zero pilots in the frequency sequence is less than or equal to the equivalent channel coherence bandwidth, and greater than or equal to the second non-zero pilot minimum anti-interference distance, the wth
  • the subcarriers corresponding to the non-zero pilots of any two pilot sequences in the K w pilot sequences on the symbol are different.
  • Embodiments of the present application normalize equivalent channel coherence bandwidth for systems with K digital channels
  • K" 0 is the equivalent channel coherence bandwidth / IFD ICI, rounded under MTI , ie
  • the embodiment of the present application requires N symbols to transmit a pilot sequence, and the symbol n (Sym n) carries a pilot sequence of K n digital channels.
  • the design of the pilot sequence on each symbol is similar to the design of the example of Figure 25.
  • the first digital channel is transmitted on the first symbol (symbol 1), and the set of non-zero pilots on the left and right sides of the DC subcarrier are respectively with
  • the second digital channel is transmitted on the second symbol (symbol 2), and the set of non-zero pilots on the left and right sides of the DC subcarrier are respectively with
  • the system has K digital channels, where K is greater than or equal to 2, and the generating a pilot sequence according to the minimum anti-interference distance of the non-zero pilot may include: The second non-zero pilot minimum anti-interference distance IFD ICI, the MTI is greater than the equivalent channel coherence bandwidth, and the first non-zero pilot minimum anti-interference distance IFD main is less than or equal to the equivalent channel coherence bandwidth, K class A pilot sequences are respectively generated on K class A symbols, and K class B pilot sequences are respectively generated on K class B symbols, wherein any two adjacent ones of the class A pilot sequences The pilot interval of the non-zero pilot is less than or equal to the equivalent channel coherence bandwidth and greater than or equal to the first non-zero pilot minimum anti-interference distance, any two of the B-type pilot sequences The pilot interval of the adjacent non-zero pilot is greater than or equal to the second non-zero pilot minimum anti-interference distance.
  • Embodiments of the present application normalize equivalent channel coherence bandwidth for systems with K digital channels
  • the ICI coefficient and the MTI coefficient are scenes that are time-invariant or slow-changing.
  • the embodiment of the present application uses a total of 2K pilot symbols to transmit a pilot sequence, for example, the odd number symbol is a class A symbol, and the even number symbol is a class B symbol.
  • the odd number symbol is a class A symbol
  • the even number symbol is a class B symbol.
  • a design similar to that of FIG. 14 is employed at the 2k-1th symbol
  • a design similar to that of FIG. 23 is employed at the 2kth symbol.
  • the pilot sequence of the 2k-1th symbol is used to estimate the equivalent channel gain
  • the 2k-1th symbol plus the pilot sequence of the 2kth symbol is used to estimate the ICI coefficient and the MTI coefficient.
  • This example uses a total of 4 symbols, the first two symbols for digital channel 1, and the last two symbols for digital channel 2.
  • the set of non-zero pilots on the left and right of the DC subcarrier on symbol 1 are with The set of non-zero pilots on the left and right sides of the DC subcarrier on symbol 2 are respectively with
  • the set of non-zero pilots on the left and right of the DC subcarrier on symbol 3 are with The set of non-zero pilots on the left and right sides of the DC subcarrier on symbol 4 are respectively with
  • the system has K digital channels, where K is greater than or equal to 2, and the generating a pilot sequence according to the minimum anti-interference distance of the non-zero pilot may include:
  • the first non-zero pilot minimum anti-interference distance IFD main is greater than the equivalent channel coherence bandwidth, and for each digital channel of the K digital channels, X class A pilot sequences are generated on X consecutive class A symbols Where X is rounded to the IFD main / equivalent channel coherence bandwidth, and a Class B pilot sequence is generated on a Class B symbol after X consecutive Class A symbols, the X of each digital channel
  • the subcarriers corresponding to the non-zero pilots of any two class A pilot sequences in the class A pilot sequence are different, and the pilot intervals of any two adjacent non-zero pilots in the class A pilot sequence are greater than Or equal to the first non-zero pilot minimum anti-interference distance, the pilot interval of any two adjacent non-zero pilots in the B-type pilot sequence is greater than or
  • Embodiments of the present application normalize equivalent channel coherence bandwidth for systems with K digital channels
  • the ICI coefficient and the MTI coefficient are scenes that are time-invariant or slow-changing.
  • (X+1)K pilot symbols are used, where the IFD main / equivalent channel coherent bandwidth is rounded, that is, X+1 symbols are used for each digital channel, with the first X consecutive symbols (Class A symbols) employing a design similar to that of Figure 14, and the X+1 symbols employing a design similar to Figure 23.
  • the pilot sequences of the first X consecutive symbols are used to estimate the equivalent channel gain, and the pilot sequences of X+1 symbols are used to estimate the ICI coefficients and the MTI coefficients.
  • the symbol index assigned by the kth digital channel can be expressed as (k-1)(M+1)+1:k(M+1) .
  • the first X (similar to the design of Figure 14) consecutive symbols of each digital channel are placed one after another. After all the K digital channels are placed, one by one are placed.
  • the X+1th (similar to the design of Fig. 23) symbol of the digital channel therefore, the symbol index assigned by the kth digital channel can be expressed as (k-1) M+1: kM and KM+k.
  • the set of non-zero pilots on the left and right of the DC subcarrier on symbol 1 are with The set of non-zero pilots on the left and right sides of the DC subcarrier on symbol 2 are respectively with The set of non-zero pilots on the left and right sides of the DC subcarrier on symbol 3 are respectively with
  • the set of non-zero pilots on the left and right sides of the DC subcarrier on symbol 4 are with The set of non-zero pilots on the left and right sides of the DC subcarrier on symbol 4 are with The set of non-zero pilots on the left and right sides of the DC subcarrier on symbol 5 are respectively with The set of non-zero pilots on the left and right sides of the DC subcarrier on symbol 6 are respectively with
  • the difference of the subcarriers corresponding to the non-zero pilots of any two pilot sequences means that the index indices of the non-zero pilots of any two pilot sequences do not overlap.
  • the effect that the embodiment of the present application can achieve is described by comparing the bit error ratio (BER) performance of the system with the existing pilot sequence design.
  • the system block diagram is shown in Figure 29.
  • the downlink OFDM system includes 64 transmit antennas and 4 receive antennas; the channel adopts the 3rd Generation Partnership Project (3GPP) Spatial Channel Model (SCM), 2 clusters 20 paths, and the second cluster
  • 3GPP 3rd Generation Partnership Project
  • SCM Spatial Channel Model
  • the delay of the first cluster is 80 ns, the power is reduced by 9 dB
  • the main direction of the first cluster of the beamforming codebook is simulated; the single digital channel;
  • the modulation mode is 16QAm;
  • the DFT point of OFDM is 256, and the subcarrier spacing is 1.44MHz, the signal bandwidth is 250MHz, of which 168 subcarriers are effective subcarriers; the independent distribution of phase and noise of the receiving and transmitting ends, and the power spectral density satisfies the model Among them,
  • the BER curve under non-coding conditions of the system is shown in FIG. It can be seen that under the condition of strong RFD, the existing scheme system is seriously affected and the performance is poor.
  • the design scheme of the pilot sequence in the embodiment of the present application fully considers the mutual influence of each strong RFD, and can be more effective.
  • the strong RFD can guarantee the reliability of communication. At the same time, this solution can also reduce the overhead of the device.
  • the embodiment of the present application further provides a method for transmitting a pilot signal, which may include: receiving a pilot sequence, where pilot intervals of any two adjacent non-zero pilots in the pilot sequence are based on Determining the spread length of the interference in the radio frequency distortion condition, the pilot between any two adjacent non-zero pilots in the pilot sequence is zero pilot, and the mirror subcarrier corresponding to the non-zero pilot subcarrier
  • the carrier is a null subcarrier; the equivalent channel gain is estimated according to the pilot sequence or at least two types of interference under the condition of estimating radio frequency distortion.
  • the method may include: receiving a pilot sequence, where a pilot interval of any two adjacent non-zero pilots in the pilot sequence is greater than or equal to 1, and any two phases in the pilot sequence a pilot between adjacent non-zero pilots is a zero pilot, and a mirror subcarrier corresponding to the subcarrier of the non-zero pilot is a null subcarrier; estimating an equivalent channel gain or estimating a radio frequency distortion condition according to the pilot sequence At least two kinds of interference.
  • the subcarriers adjacent to the left and right of the mirror subcarriers corresponding to the subcarriers of the non-zero pilot are also null subcarriers.
  • the pilot sequence is used to estimate an equivalent channel gain, which is generated according to an equivalent channel coherence bandwidth of the system, where the pilot interval causes interference to interfere with non-zero pilots.
  • a threshold is used to estimate an equivalent channel gain, which is generated according to an equivalent channel coherence bandwidth of the system, where the pilot interval causes interference to interfere with non-zero pilots.
  • the pilot sequence is used to estimate at least two types of interference in a radio frequency distortion condition, where the pilot interval causes the impact of the at least two types of interference on a non-zero pilot to be less than a first threshold. And the pilot spacing is such that an effect of the at least two interferences relative to one another is less than a second threshold.
  • the method may further include: receiving a data signal on the symbol of receiving the pilot sequence.
  • the receiving a pilot sequence includes: receiving, on a first type of symbol, a first type of pilot sequence, where any two adjacent non-zero derivatives in the first type of pilot sequence
  • the first pilot spacing of the frequency causes the interference to have a lesser impact on the non-zero pilot than the first threshold
  • the second type of pilot sequence is received on the second type of symbol, any two adjacent to the second type of pilot sequence
  • the second pilot interval of the non-zero pilot is such that the influence of the interference on the non-zero pilot is less than the first threshold, and the second pilot interval is such that the influence of the at least two interferences relative to each other is less than the second threshold
  • Estimating the equivalent channel gain or estimating at least two types of interference based on the pilot sequence including estimating an equivalent channel gain based on the first type of pilot sequence. At least two types of interference under radio frequency distortion conditions are estimated based on the second type of pilot sequence.
  • the pilot sequence is generated by concatenating a plurality of basic pilot units, where the basic pilot unit includes a non-zero pilot.
  • the extended length includes inter-carrier interference ICI extended length and image interference.
  • the MTI extends the length, and the two types of interference include ICI and MTI.
  • a pilot interval of any two adjacent non-zero pilots in the pilot sequence is greater than or equal to the non-zero pilot minimum anti-interference distance, the non-zero The pilot minimum anti-interference distance is determined according to the extended length of the interference under the radio frequency distortion condition.
  • FIG. 31 shows a schematic block diagram of an apparatus 2600 for transmitting pilot signals in accordance with an embodiment of the present application. As shown in FIG. 31, the device 2600 includes:
  • the processing module 2610 is configured to determine a pilot interval of any two adjacent non-zero pilots in the pilot sequence, where the pilot interval is determined according to an extended length of interference under radio frequency distortion conditions;
  • the processing module 2610 is further configured to generate the pilot sequence according to the pilot interval, where a pilot between any two adjacent non-zero pilots in the pilot sequence is zero pilot, the guide
  • the mirror subcarrier corresponding to the subcarrier of the non-zero pilot of the frequency sequence is an empty subcarrier;
  • the sending module 2620 is configured to send the pilot sequence generated by the processing module 2610.
  • the pilot sequence is allocated a non-zero pilot carrier, and a zero pilot carrier is also allocated thereto, and the pilot interval design of the non-zero pilot is based on the principle of not being interfered.
  • the influence of non-zero pilot carrier and data is significantly reduced, which makes the system less affected by RF distortion and improves system performance.
  • the subcarriers adjacent to the left and right of the mirror subcarriers corresponding to the subcarriers of the non-zero pilot are also null subcarriers.
  • the pilot sequence is used to estimate an equivalent channel gain
  • the pilot interval is such that the impact of the interference on the non-zero pilot is less than the first threshold
  • the processing module 2610 is configured according to the guide Generating the pilot sequence at a frequency interval, including:
  • the pilot sequence is generated based on the pilot interval and an equivalent channel coherence bandwidth of the system.
  • the pilot sequence is used to estimate at least two types of interference in a radio frequency distortion condition, where the pilot interval causes the impact of the at least two types of interference on a non-zero pilot to be less than a first threshold. And the pilot spacing is such that an effect of the at least two interferences relative to one another is less than a second threshold.
  • the sending module 2620 is specifically configured to send the pilot sequence on a corresponding symbol; the sending module 2620 is further configured to: further send a data signal on the symbol.
  • the pilot sequence includes a first type of pilot sequence and a second type of pilot sequence, where the first type of pilot sequence is used to estimate an equivalent channel gain, the first class a pilot interval of any two adjacent non-zero pilots in the pilot sequence is a first pilot interval, and the second type of pilot sequence is used to estimate at least two types of interference in a radio frequency distortion condition, the second The pilot interval of any two adjacent non-zero pilots in the pilot-like sequence is the second pilot interval, and the processing module 2610 generates the pilot sequence according to the pilot interval, including:
  • the first type of pilot sequence being generated according to the first pilot interval and an equivalent channel coherence bandwidth of the system, the first pilot interval causing interference to non-zero pilots The impact is less than the first threshold;
  • the second type of pilot sequence is generated according to the second pilot interval, and the second of any two adjacent non-zero pilots in the second type of pilot sequence
  • the pilot interval is such that the influence of the interference on the non-zero pilot is less than the first threshold
  • the second pilot interval is such that the influence of the at least two interferences relative to each other is less than the second threshold
  • the sending module 2620 is specifically configured to:
  • the second type of pilot sequence is transmitted on a second type of symbol.
  • the pilot sequence is generated by concatenating a plurality of basic pilot units, where the basic pilot unit includes a non-zero pilot.
  • the extended length includes an inter-carrier interference ICI extension length and a mirror interference MTI extension length.
  • the processing module 2610 determines a pilot interval of any two adjacent non-zero pilots in the pilot sequence, including:
  • a pilot interval of any two adjacent non-zero pilots in the pilot sequence is greater than or equal to a minimum of the non-zero pilot Anti-interference distance.
  • the processing module 2610 may be implemented by a processor, and the sending module 2620 may be implemented by a transceiver.
  • the device 2700 that transmits the pilot signals can include a processor 2710, a transceiver 2720, and a memory 2730.
  • the memory 2730 can be used to store code and the like executed by the processor 2710.
  • bus system 2740 which in addition to the data bus includes a power bus, a control bus, and a status signal bus.
  • the device 2600 shown in FIG. 31 or the receiving end 2700 shown in FIG. 32 can implement the various processes implemented in the foregoing embodiments of FIG. 7 to FIG. 30. To avoid repetition, details are not described herein again.
  • the processor 2710 may be a central processing unit (“CPU"), and the processor 2710 may also be other general-purpose processors, digital signal processors (DSPs). , an application specific integrated circuit (ASIC), an off-the-shelf programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, and the like.
  • the general purpose processor may be a microprocessor or the processor or any conventional processor or the like.
  • the memory 2720 can include read only memory and random access memory and provides instructions and data to the processor 2710. A portion of the memory 2720 can also include a non-volatile random access memory. For example, the memory 2720 can also store information of the device type.
  • the bus system 2730 may include a power bus, a control bus, a status signal bus, and the like in addition to the data bus. However, for clarity of description, various buses are labeled as bus system 2730 in the figure.
  • each step of the above method may be completed by an integrated logic circuit of hardware in the processor 2710 or an instruction in a form of software.
  • the steps of the method disclosed in the embodiments of the present application may be directly implemented as a hardware processor, or may be performed by a combination of hardware and software modules in the processor.
  • the software module can be located in a conventional storage medium such as random access memory, flash memory, read only memory, programmable read only memory or electrically erasable programmable memory, registers, and the like.
  • the storage medium is located in the memory 2720, and the processor 2710 reads the information in the memory 2720 and completes the steps of the above method in combination with its hardware. To avoid repetition, it will not be described in detail here.
  • the embodiment of the present application further provides a device (receiving end) for transmitting a pilot signal.
  • the device includes:
  • a receiving module configured to receive a pilot sequence, where pilot intervals of any two adjacent non-zero pilots in the pilot sequence are determined according to an extended length of interference under radio frequency distortion conditions, where any of the pilot sequences a pilot between two adjacent non-zero pilots is a zero pilot, and a mirror subcarrier corresponding to the subcarrier of the non-zero pilot is an empty subcarrier;
  • a processing module configured to estimate an equivalent channel gain or estimate at least two types of interference under the radio frequency distortion condition according to the pilot sequence received by the receiving module.
  • the receiving module may be configured to receive a pilot sequence, where a pilot interval of any two adjacent non-zero pilots in the pilot sequence is greater than or equal to 1, and any two phases in the pilot sequence a pilot between the non-zero pilots of the neighbor is a zero pilot, and the mirrored subcarrier corresponding to the subcarrier of the non-zero pilot is an empty subcarrier; the processing module may be configured to use the pilot received according to the receiving module
  • the sequence estimates the equivalent channel gain or estimates at least two types of interference under radio frequency distortion conditions.
  • the system when the system allocates a non-zero pilot carrier, the system also allocates a zero pilot carrier, and the pilot interval design of the non-zero pilot is based on the principle of not being interfered, so that the non-zero pilot carrier is used.
  • the influence of the interference on the data is significantly weakened, so that the system is less affected by the radio frequency distortion, and the system can more accurately estimate the equivalent channel gain or estimate at least two kinds of interference under the condition of radio frequency distortion, thereby improving the performance of the system.
  • the subcarriers adjacent to the left and right of the mirror subcarriers corresponding to the subcarriers of the non-zero pilot are also null subcarriers.
  • the pilot sequence is used to estimate an equivalent channel gain, which is generated according to an equivalent channel coherence bandwidth of the system, where the pilot interval causes interference to have less impact on non-zero pilots.
  • a threshold is used to estimate an equivalent channel gain, which is generated according to an equivalent channel coherence bandwidth of the system, where the pilot interval causes interference to have less impact on non-zero pilots.
  • the pilot sequence is used to estimate at least two types of interference in a radio frequency distortion condition, where the pilot interval causes the impact of the at least two types of interference on a non-zero pilot to be less than a first threshold. And the pilot spacing is such that an effect of the at least two interferences relative to one another is less than a second threshold.
  • the receiving module is further configured to receive a data signal on the symbol of receiving the pilot sequence.
  • the receiving module is specifically configured to receive, on a first type of symbol, a first type of pilot sequence, where any two adjacent non-zero pilots in the first type of pilot sequence
  • the first pilot interval is such that the effect of the interference on the non-zero pilot is less than the first threshold
  • the second type of pilot sequence is received on the second type of symbols, any two adjacent non-zero of the second type of pilot sequence
  • the second pilot interval of the pilot is such that the effect of the interference on the non-zero pilot is less than the first threshold
  • the second pilot interval is such that the influence of the at least two interferences relative to each other is less than the second threshold
  • the module is specifically configured to: estimate an equivalent channel gain according to the first type of pilot sequence. At least two types of interference under radio frequency distortion conditions are estimated based on the second type of pilot sequence.
  • the pilot sequence is generated by concatenating a plurality of basic pilot units, where the basic pilot unit includes a non-zero pilot.
  • the extended length includes an inter-carrier interference ICI extended length and a mirrored interference MTI extended length, where the two types of interference include ICI and MTI.
  • a pilot interval of any two adjacent non-zero pilots in the pilot sequence is greater than or equal to the non-zero pilot minimum anti-interference distance, the non-zero The pilot minimum anti-interference distance is determined according to the extended length of the interference under the radio frequency distortion condition.
  • the receiving module may be implemented by a transceiver
  • the processing module may be implemented by a processor.
  • the device that transmits the pilot signal can include a processor, a transceiver, and a memory.
  • the memory can be used to store code executed by the processor and the like.
  • bus system includes a power bus, a control bus, and a status signal bus in addition to the data bus.
  • the device for transmitting the pilot signal at the transmitting end can implement the various processes implemented in the foregoing embodiments of FIG. 7 to FIG. 30. To avoid repetition, details are not described herein again.
  • the terminal device can communicate with one or more core networks via a Radio Access Network (RAN), and the terminal device can refer to a user equipment (User Equipment, UE), access terminal, subscriber unit, subscriber station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent or user equipment.
  • the access terminal may be a cellular phone, a cordless phone, a Session Initiation Protocol (SIP) phone, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA), with wireless communication.
  • the network device may be a device for communicating with the terminal device, for example, may be a base station (Base Transceiver Station, BTS) in the GSM system or CDMA, or may be a base station (NodeB, NB) in the WCDMA system, or may be An evolved base station (Evolutional Node B, eNB or eNodeB) in an LTE system, or the network device may be a relay station, an access point, an in-vehicle device, a wearable device, and a network side device in a future 5G network or a future evolved PLMN network. Network devices, etc.
  • the term "article of manufacture” as used in this application encompasses a computer program accessible from any computer-readable device, carrier, or media.
  • the computer readable medium may include, but is not limited to, a magnetic storage device (eg, a hard disk, a floppy disk, or a magnetic tape, etc.), such as a compact disk (CD), a digital versatile disk (Digital Versatile Disk, DVD). Etc.), smart cards and flash memory devices (eg, Erasable Programmable Read-Only Memory (EPROM), cards, sticks or key drivers, etc.).
  • various storage media described herein can represent one or more devices and/or other machine-readable media for storing information.
  • the term "machine-readable medium” may include, without limitation, a wireless channel and various other mediums capable of storing, containing, and/or carrying instructions and/or data.
  • the size of the sequence numbers of the foregoing processes does not mean the order of execution sequence, and the order of execution of each process should be determined by its function and internal logic, and should not be applied to the embodiment of the present application.
  • the implementation process constitutes any limitation.
  • the disclosed systems, devices, and methods may be implemented in other manners.
  • the device embodiments described above are merely illustrative.
  • the division of the unit is only a logical function division.
  • there may be another division manner for example, multiple units or components may be combined or Can be integrated into another system, or some features can be ignored or not executed.
  • Another The coupling or direct coupling or communication connection between the points shown or discussed may be an indirect coupling or communication connection through some interface, device or unit, and may be in electrical, mechanical or other form.
  • the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of the embodiment.
  • each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.
  • the functions may be stored in a computer readable storage medium if implemented in the form of a software functional unit and sold or used as a standalone product.
  • the technical solution of the present application which is essential or contributes to the prior art, or a part of the technical solution, may be embodied in the form of a software product, which is stored in a storage medium, including
  • the instructions are used to cause a computer device (which may be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present application.
  • the foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk, and the like, which can store program codes. .

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Abstract

本申请公开了一种传输导频信号的方法和设备，该方法包括：确定导频序列中任意两个相邻的非零导频的导频间隔，所述导频间隔是根据射频失真条件下干扰的扩展长度确定的；根据所述导频间隔生成所述导频序列，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，所述导频序列的非零导频的子载波对应的镜像子载波为空子载波；发送所述导频序列。因此，本申请提供的传输导频信号的方法，为系统分配非零导频载波的同时，还为系统分配零导频载波。非零导频的设计基于不被不干扰的原则，使非零导频载波和数据受到干扰的影响明显减弱，从而使得系统受射频失真的影响较小，提升系统的性能。

Description

传输导频信号的方法和设备
本申请要求于2016年4月20日提交中国专利局、申请号为201610248563.1、发明名称为“传输导频信号的方法和设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及通信领域，并且更具体地，涉及传输导频信号的方法和设备。
背景技术
导频信号，也称为导频序列，包括非零导频(non-zero pilot)和零导频(又称为空导频，null pilot)。导频序列常用于通信系统的信道估计和射频失真(Radio Frequency Distortion)补偿。信道和射频失真的特性取决于环境、频率范围、系统设置和收发器的实现误差等因素。因此，不同条件下的导频序列的设计也有所差异。此外，导频信号在频域传输或在时域上传输时，其设计也有区别。
频域的导频信号主要应用于多载波系统如正交频分复用(Orthogonal Frequency Division Multiplexing，OFDM)系统、单载波频分多址(Single-carrier Frequency-Division Multiple Access，SC-FDMA)系统和离散傅里叶变换预编码的正交频分复用(Discrete Fourier Transform-Precoded OFDM，DFT-precoded OFDM)系统等。导频信号可以用于估计信道，估计射频失真条件下的干扰，例如相噪、频偏和同相和正交相位不平衡(In-phase and Quadrature-phase Imbalance，IQI)，还可以用于单载波系统频域均衡。
现有的导频序列的设计方案主要分为无射频失真条件下的导频序列的设计和射频失真条件下的导频序列设计。现有的射频失真条件下的导频序列的设计方案主要有针对信道+IQI的导频序列设计、针对信道+相位噪声的导频序列设计和针对信道+相位噪声+频偏的导频序列设计等等。但是针对相噪引起的载波间干扰(Inter-Carrier/Inter-sub-Carrier Interference，ICI)和IQI引起的镜像干扰(Mirror Tone Interference，MTI)的导频序列设计则较少。
现有的导频序列设计方案，要么只考虑镜像干扰(MTI)，要么只考虑载波间干扰(ICI)，或者MTI和ICI的影响均未考虑。因此，当RFD水平较高时，ICI和/或MTI会严重影响系统的性能，使得系统在现有的导频设计方案下无法正常工作。
发明内容
本申请提供一种传输导频信号的方法和设备，能够减小射频失真对系统的影响，提高系统的性能。
第一方面，提供了一种传输导频信号的方法，所述方法包括：确定导频序列中任意两个相邻的非零导频的导频间隔，所述导频间隔是根据射频失真条件下干扰的扩展长度确定的；根据所述导频间隔生成所述导频序列，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，所述导频序列的非零导频的子载波对应的镜像子载波为空子载波；发送所述导频序列。
换而言之，该方法可以包括：生成导频序列，所述导频序列中任意两个相邻的非零导频的导频间隔是根据射频失真条件下干扰的扩展长度确定的，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，所述非零导频的子载波对应的镜像子载波为空子载波；发送所述导频序列。
从结果上来看，该方法可以包括：确定导频序列中任意两个相邻的非零导频的导频间隔，所述导频间隔大于或等于1；根据所述导频间隔生成所述导频序列，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，所述导频序列的非零导频的子载波对应的镜像子载波为空子载波；发送所述导频序列。或者，该方法可以包括：生成导频序列，所述导频序列中任意两个相邻的非零导频的导频间隔大于或等于1，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，所述非零导频的子载波对应的镜像子载波为空子载波；发送所述导频序列。
因此，在本申请中，为系统分配非零导频载波的同时，还为系统分配零导频载波，非零导频的导频间隔设计基于不被不干扰的原则，使非零导频载波和数据受到干扰的影响明显减弱，从而使得系统受射频失真的影响较小，提升系统的性能。
在第一方面的一种可能的实现方式中，所述确定导频序列中任意两个相邻的非零导频的导频间隔，可以包括：根据所述射频失真条件下干扰的扩展长度，确定非零导频最小抗干扰距离；根据所述非零导频最小抗干扰距离，确定所述导频间隔，所述导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述非零导频最小抗干扰距离。
可选地，所述扩展长度包括载波间干扰ICI扩展长度和镜像干扰MTI扩展长度。或者，换而言之，干扰包括载波间干扰ICI和镜像干扰MTI。
在本实现方式中，同时考虑相噪引起ICI以及IQI引起MTI的影响。根据射频失真条件下ICI扩展长度和MTI扩展长度确定导频序列中任意两个相邻的非零导频的导频间隔，导频序列中任意两个相邻的非零导频之间的导频为零导频，由此将ICI和IQI与非零导频错开，使干扰不影响导频子载波，从而提升系统的性能。
在第一方面的一种可能的实现方式中，所述非零导频的子载波对应的镜像子载波左右分别相邻的子载波为空子载波。由此，可以进一步减小MTI对系统性能的影响。
在第一方面的一种可能的实现方式中，所述导频序列用于估计等效信道增益，所述导频间隔使得干扰对非零导频的影响小于第一阈值，所述根据所述导频间隔生成所述导频序列，包括：根据所述导频间隔和系统的等效信道相干带宽，生成所述导频序列。本可能的实现方式，用于估计等效信道增益的场景，其设计使得导频序列最终等效的导频间隔使得干扰对非零导频的影响小于第一阈值，且导频序列最终等效的导频间隔小于或等于系统的等效信道相干带宽。
在第一方面的另一种可能的实现方式中，所述导频序列用于估计射频失真条件下的至少两种干扰，所述导频间隔使得所述至少两种干扰对非零导频的影响小于第一阈值，并且所述导频间隔使得所述至少两种干扰相互之间的影响小于第二阈值。
本可能的实现方式中，所述方法还包括：所述发送所述导频序列，包括：在相应的符号上发送所述导频序列；所述方法还包括：在所述符号上还发送数据信号。
在第一方面的另一种可能的实现方式中，所述导频序列包括第一类导频序列和第二类导频序列，所述第一类导频序列用于估计等效信道增益，所述第一类导频序列中任意两个相邻的非零导频的导频间隔为第一导频间隔，所述第二类导频序列用于估计射频失 真条件下的至少两种干扰，所述第二类导频序列中任意两个相邻的非零导频的导频间隔为第二导频间隔，所述根据所述导频间隔生成所述导频序列，包括：生成所述第一类导频序列，所述第一类导频序列根据所述第一导频间隔和系统的等效信道相干带宽生成，所述第一导频间隔使得干扰对非零导频的影响小于第一阈值；生成所述第二类导频序列，所述第二类导频序列根据所述第二导频间隔生成，所述第二类导频序列中任意两个相邻的非零导频的第二导频间隔使得干扰对非零导频的影响小于第一阈值，并且所述第二导频间隔使得所述至少两种干扰相互之间的影响小于第二阈值；所述发送所述导频序列，包括：在第一类符号上发送所述第一类导频序列；在第二类符号上发送所述第二类导频序列。
在第一方面的一种可能的实现方式中，所述导频序列由多个基本导频单元级联生成，所述基本导频单元中包括一个非零导频。
第二方面，提供了一种传输导频信号的方法，所述方法包括：获取射频失真条件下的载波间干扰ICI扩展长度和镜像干扰MTI扩展长度；根据所述ICI扩展长度和所述MTI扩展长度，确定非零导频最小抗干扰距离；根据所述非零导频最小抗干扰距离，生成导频序列，所述导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述非零导频最小抗干扰距离，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，且非零导频的子载波对应的镜像子载波为空子载波；发送所述导频序列。
换而言之，所述方法包括：根据射频失真条件下的载波间干扰ICI扩展长度和镜像干扰MTI扩展长度，确定非零导频最小抗干扰距离；根据所述非零导频最小抗干扰距离，生成导频序列，所述导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述非零导频最小抗干扰距离，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，且非零导频的子载波对应的镜像子载波为空子载波；发送所述导频序列。
在第二方面的一种可能的实现方式中，所述导频序列用于估计等效信道增益，所述ICI扩展长度为κ个子载波，所述MTI扩展长度为ι个子载波，所述根据所述ICI扩展长度和所述MTI扩展长度，确定非零导频最小抗干扰距离，包括：根据所述ICI扩展长度为κ个子载波和所述MTI扩展长度为ι个子载波，确定用于估计等效信道增益的第一非零导频最小抗干扰距离IFDmain＝max(κ+1,2ι+2)。
其中，IFDmain＝max(κ+1,2ι+2)是一种可选的实现方式，其镜像子载波占一个子载波，MTI的单边扩展长度为ι，双边扩展长度为为2ι，因此需要的空载波个数为2ι+1，非零导频的导频间隔从MTI角度看需要大于或等于2ι+2。
在第二方面的一种可能的实现方式中，非零导频的子载波对应的镜像子载波左右分别相邻的子载波可以为空子载波。
其中，一种具体的例子为：所述系统具有单数字通道，所述根据所述非零导频最小抗干扰距离，生成导频序列，包括：如果所述第一非零导频最小抗干扰距离IFDmain小于或等于等效信道相干带宽，在一个符号上生成所述导频序列，所述导频序列中的任意两个相邻的非零导频的导频间隔小于或等于所述等效信道相干带宽，且大于或等于所述第 一非零导频最小抗干扰距离；如果所述第一非零导频最小抗干扰距离IFDmain大于所述等效信道相干带宽，在M个符号上生成M个导频序列，所述导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述第一非零导频最小抗干扰距离，所述M个导频序列中的任意两个导频序列的非零导频对应的子载波不同，其中，M为对IFDmain/等效信道相干带宽上取整。
另一种具体的例子为：所述系统具有K个数字通道，其中，K大于或等于2，所述根据所述非零导频最小抗干扰距离，生成导频序列，包括：如果所述第一非零导频最小抗干扰距离IFDmain的K倍小于或等于等效信道相干带宽，在一个符号上生成K个导频序列，所述K个导频序列中的每个导频序列中任意两个相邻的非零导频的导频间隔小于或等于所述等效信道相干带宽，且大于或等于所述第一非零导频最小抗干扰距离，所述K个导频序列中的任意两个导频序列的非零导频对应的子载波不同；如果所述第一非零导频最小抗干扰距离IFDmain的K倍大于所述等效信道相干带宽，且所述第一非零导频最小抗干扰距离IFDmain小于或等于所述等效信道相干带宽，在N个符号上生成K个导频序列，其中，N小于或等于K，第n个符号上生成Kn个导频序列，n的取值为1,2,...,N，Kn小于或等于K0，K0为对等效信道相干带宽/IFDmain下取整，所述第n个符号上的Kn个导频序列中的每个导频序列中任意两个相邻的非零导频的导频间隔小于或等于所述等效信道相干带宽，且大于或等于所述第一非零导频最小抗干扰距离，所述第n个符号上的Kn个导频序列中的任意两个导频序列的非零导频对应的子载波不同；如果所述第一非零导频最小抗干扰距离IFDmain大于所述等效信道相干带宽，在MK个符号上生成MK个导频序列，每个数字通道在M个符号上生成M个导频序列，其中，M为对IFDmain/等效信道相干带宽上取整，每个导频序列中任意两个相邻的非零导频的导频间隔大于或等于所述第一非零导频最小抗干扰距离，每个数字通道的所述M个导频序列中的任意两个导频序列的非零导频对应的子载波不同。
在第二方面的一种可能的实现方式中，所述ICI扩展长度为κ个子载波，所述MTI扩展长度为ι个子载波，所述根据所述ICI扩展长度和所述MTI扩展长度，确定非零导频最小抗干扰距离，包括：根据所述ICI扩展长度为κ个子载波和所述MTI扩展长度为ι个子载波，确定用于估计ICI和MTI的第二非零导频最小抗干扰距离IFDICI,MTI＝2(κ+ι+1)。
应理解，所述导频序列用于估计ICI和MTI，或，所述导频序列用于估计等效信道增益以及估计ICI和MTI。
一种具体的例子为：所述系统具有单数字通道，所述根据所述非零导频最小抗干扰 距离，生成导频序列，包括：如果所述导频序列的长度小于或等于一个符号上导频可用信道带宽，在一个符号的直流载波的左侧的连续子载波组和右侧的连续子载波组上分别生成包括V个非零导频的导频序列，所述导频序列中任意两个相邻的非零导频的导频间隔大于或等于所述第二非零导频最小抗干扰距离，其中，V大于1。
另一种具体的例子为：所述系统具有K个数字通道，其中，K大于或等于2，所述根据所述非零导频最小抗干扰距离，生成导频序列，包括：如果K个数字通道的导频序列的总长度小于或等于一个符号上导频可用信道带宽，在一个符号上生成K个导频序列，所述K个导频序列中每个导频序列中任意两个相邻的非零导频的导频间隔大于或等于所述第二非零导频最小抗干扰距离，所述K个导频序列中的任意两个导频序列的非零导频对应的子载波不同；如果K个数字通道的导频序列的总长度大于一个符号上导频可用信道带宽，在T个符号上生成K个导频序列，其中，T小于或等于K，第t个符号的导频可用信道带宽上生成Kt个导频序列，t的取值为1,2,...,T，Kt小于或等于K'0，一个符号最多可传输K'0个数字通道的导频序列，所述K个导频序列中每个导频序列中任意两个相邻的非零导频的导频间隔大于或等于所述第二非零导频最小抗干扰距离，所述第t个符号上的Kt个导频序列中的任意两个导频序列的非零导频对应的子载波不同。其中，每个导频序列中包括V个非零导频，V大于1。
第二方面的一种可能的实现方式中，所述导频序列由基本导频单元级联生成，所述基本导频单元中包括一个非零导频，两个所述基本导频单元级联时，两个所述基本导频单元中的两个非零导频的导频间隔大于或等于所述第二非零导频最小抗干扰距离。
第二方面的一种可能的实现方式中，所述方法还包括：在发送所述导频序列的符号上，还发送数据信号。
第二方面的一种可能的实现方式中，所述系统具有单数字通道，所述根据所述非零导频最小抗干扰距离，生成导频序列，包括：如果所述第二非零导频最小抗干扰距离IFDICI,MTI小于或等于等效信道相干带宽，在一个符号上生成所述导频序列，所述导频序列中的任意两个相邻的非零导频的导频间隔小于或等于所述等效信道相干带宽，且大于或等于所述第二非零导频最小抗干扰距离；如果所述第二非零导频最小抗干扰距离IFDICI,MTI大于所述等效信道相干带宽，在U个符号上分别生成U个导频序列，所述U个导频序列中的任意两个导频序列的非零导频对应的子载波不同，所述U个导频序列中的每个导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述第二非零导频最小抗干扰距离其中，U为对IFDICI,MTI/等效信道相干带宽上取整。
本实现方式中，所述导频序列可以用于估计等效信道增益以及估计ICI和MTI。
第二方面的一种可能的实现方式中，所述ICI扩展长度为κ个子载波，所述MTI扩展长度为ι个子载波，所述根据所述ICI扩展长度和所述MTI扩展长度，确定非零导频 最小抗干扰距离，包括：根据所述ICI扩展长度为κ个子载波和所述MTI扩展长度为ι个子载波，确定用于估计等效信道增益的第一非零导频最小抗干扰距离IFDmain＝max(κ+1,2ι+2)；根据所述ICI扩展长度为κ个子载波和所述MTI扩展长度为ι个子载波，确定用于估计ICI和MTI的第二非零导频最小抗干扰距离IFDICI,MTI＝2(κ+ι+1)。
本实现方式中，所述导频序列可以用于估计等效信道增益以及估计ICI和MTI。
一种具体的例子为：所述系统具有单数字通道，所述根据所述非零导频最小抗干扰距离，生成导频序列，包括：在第一类符号上生成第一类导频序列，所述第一类导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述第一非零导频最小抗干扰距离；在所述第一类符号后的第二类符号上生成第二类导频序列，所述第二类导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述第二非零导频最小抗干扰距离。
具体地，如果所述第一非零导频最小抗干扰距离IFDmain小于或等于等效信道相干带宽，在一个第一类符号上生成一个第一类导频序列，所述第一类导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述第一非零导频最小抗干扰距离，且小于或等于所述等效信道相干带宽；如果所述第一非零导频最小抗干扰距离IFDmain大于所述等效信道相干带宽，在Y个符号上生成Y个第一类导频序列，所述第一类导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述第一非零导频最小抗干扰距离，所述Y个第一类导频序列中的任意两个第一类导频序列的非零导频对应的子载波不同，其中，Y为对IFDmain/等效信道相干带宽上取整；在所述第一类符号后的第二类符号上生成第二类导频序列，所述第二类导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述第二非零导频最小抗干扰距离。
另一种具体的例子为：所述系统具有K个数字通道，其中，K大于或等于2，所述根据所述非零导频最小抗干扰距离，生成导频序列，包括：如果所述第二非零导频最小抗干扰距离IFDICI,MTI的K倍小于或等于等效信道相干带宽，在一个符号上生成K个导频序列，所述K个导频序列中的每个导频序列中任意两个相邻的非零导频的导频间隔小于或等于所述等效信道相干带宽，且大于或等于所述第二非零导频最小抗干扰距离，所述K个导频序列中的任意两个导频序列的非零导频对应的子载波不同；如果所述第二非零导频最小抗干扰距离IFDICI,MTI的K倍大于所述等效信道相干带宽，且所述第二非零导频最小抗干扰距离IFDICI,MTI小于或等于所述等效信道相干带宽，在W个符号上生成K个导频序列，其中，W小于或等于K，第w个符号上生成Kw个导频序列，w的取值为1,2,...,W，Kw小于或等于K”0，K”0为对等效信道相干带宽/IFDICI,MTI下取整，所述第w个符号上的Kw个导频序列中的每个导频序列中任意两个相邻的非零导频的导频 间隔小于或等于所述等效信道相干带宽，且大于或等于所述第二非零导频最小抗干扰距离，所述第w个符号上的Kw个导频序列中的任意两个导频序列的非零导频对应的子载波不同；如果所述第二非零导频最小抗干扰距离IFDICI,MTI大于所述等效信道相干带宽，且所述第一非零导频最小抗干扰距离IFDmain小于或等于所述等效信道相干带宽，在K个A类符号上分别生成K个A类导频序列，在K个B类符号上分别生成K个B类导频序列，其中，所述A类导频序列中的任意两个相邻的非零导频的导频间隔小于或等于所述等效信道相干带宽，且大于或等于所述第一非零导频最小抗干扰距离，所述B类导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述第二非零导频最小抗干扰距离；如果所述第一非零导频最小抗干扰距离IFDmain大于所述等效信道相干带宽，对于K个数字通道的每个数字通道，在X个连续的A类符号上生成X个A类导频序列，其中，X为对IFDmain/等效信道相干带宽上取整，在X个连续的A类符号后的一个B类符号上生成一个B类导频序列，每个数字通道的所述X个A类导频序列中的任意两个A类导频序列的非零导频对应的子载波不同，所述A类导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述第一非零导频最小抗干扰距离，所述B类导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述第二非零导频最小抗干扰距离。
第三方面，提供了一种传输导频信号的方法，包括：接收导频序列，所述导频序列中任意两个相邻的非零导频的导频间隔是根据射频失真条件下干扰的扩展长度确定的，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，所述非零导频的子载波对应的镜像子载波为空子载波；根据所述导频序列估计等效信道增益或估计射频失真条件下的至少两种干扰。
从结果上来看，该方法可以包括：接收导频序列，所述导频序列中任意两个相邻的非零导频的导频间隔大于或等于1，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，所述非零导频的子载波对应的镜像子载波为空子载波；根据所述导频序列估计等效信道增益或估计射频失真条件下的至少两种干扰。
在第三方面的一种可能的实现方式中，所述非零导频的子载波对应的镜像子载波左右分别相邻的子载波也为空子载波。
在第三方面的一种可能的实现方式中，所述导频序列用于估计等效信道增益，是根据系统的等效信道相干带宽生成的，所述导频间隔使得干扰对非零导频的影响小于第一阈值。
在第三方面的另一种可能的实现方式中，所述导频序列用于估计射频失真条件下的至少两种干扰，所述导频间隔使得所述至少两种干扰对非零导频的影响小于第一阈值，并且所述导频间隔使得所述至少两种干扰相互之间的影响小于第二阈值。
其中，所述方法可以还包括：在接收所述导频序列的符号上，还接收数据信号。
在第三方面的另一种可能的实现方式中，所述接收导频序列，包括：在第一类符号上接收第一类导频序列，所述第一类导频序列中任意两个相邻的非零导频的第一导频间 隔使得干扰对非零导频的影响小于第一阈值；在第二类符号上接收第二类导频序列，所述第二类导频序列中任意两个相邻的非零导频的第二导频间隔使得干扰对非零导频的影响小于第一阈值，并且所述第二导频间隔使得所述至少两种干扰相互之间的影响小于第二阈值；所述根据所述导频序列估计等效信道增益或估计射频失真条件下的至少两种干扰，包括：根据所述第一类导频序列估计等效信道增益。根据所述第二类导频序列估计射频失真条件下的至少两种干扰。
在第三方面的一种可能的实现方式中，所述导频序列由多个基本导频单元级联生成，所述基本导频单元中包括一个非零导频。
在第三方面的一种可能的实现方式中，所述扩展长度包括载波间干扰ICI扩展长度和镜像干扰MTI扩展长度，所述少两种干扰包括ICI和MTI。
在第三方面的一种可能的实现方式中，所述所述导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述非零导频最小抗干扰距离，所述非零导频最小抗干扰距离是根据所述射频失真条件下干扰的扩展长度确定的。
第四方面提供了一种传输导频信号的设备，该设备用于执行上述第一方面或第一方面的任一可能的实现方式中的方法。该设备可以包括处理模块和发送模块。
第五方面提供了一种传输导频信号的设备，该设备包括处理器、收发器和存储器，用于执行第一方面和其相应的实现方式，并且第五方面的设备的各器件可以与第四方面的设备相应模块对应。
附图说明
图1是一种导频序列设计方案的示意图。
图2是另一种导频序列设计方案的示意图。
图3是另一种导频序列设计方案的示意图。
图4、图5和图6是本申请实施例的导频序列设计方案的示意图。
图7是本申请一个实施例的传输导频信号方法的示意性流程图。
图8、图9和图10是本申请实施例的第一组设计方案的设计思想示意图。
图11和图12示出是本申请实施例的第二组设计方案和第三组设计方案的设计思想的示意图。
图13是本申请实施例的导频序列设计下RFD对各个子载波的影响的示意图。
图14是本申请一个实施例的导频序列设计的示意图。
图15是本申请另一个实施例的导频序列设计的示意图。
图16是本申请另一个实施例的导频序列设计的示意图。
图17是本申请另一个实施例的导频序列设计的示意图。
图18是本申请另一个实施例的导频序列设计的示意图。
图19是本申请另一个实施例的导频序列设计的示意图。
图20是本申请另一个实施例的导频序列设计的示意图。
图21是本申请另一个实施例的导频序列设计的示意图。
图22是本申请另一个实施例的导频序列设计的示意图。
图23是本申请另一个实施例的导频序列设计的示意图。
图24是本申请另一个实施例的导频序列设计的示意图。
图25是本申请另一个实施例的导频序列设计的示意图。
图26是本申请另一个实施例的导频序列设计的示意图。
图27是本申请另一个实施例的导频序列设计的示意图。
图28是本申请另一个实施例的导频序列设计的示意图。
图29是应用本申请一个实施例的OFDM系统的示意性框图。
图30是应用本申请一个实施例的系统的误比特率的曲线图。
图31是本申请一个实施例的传输导频信号设备的示意性框图。
图32是本申请另一个实施例的传输导频信号设备的示意性框图。
具体实施方式
下面将结合附图，对本申请实施例中的技术方案进行描述。
导频信号，本申请实施例中也称为导频序列，包括非零导频(non-zero pilot)和零导频(又称为空导频，null pilot)。导频序列常用于通信系统的信道估计和射频失真(Radio Frequency Distortion)补偿。信道和射频失真的特性取决于环境、频率范围、系统设置和收发器的实现误差等因素。因此，不同条件下的导频序列的设计也有所差异。此外，导频信号在频域传输或在时域上传输时，其设计也有区别。本申请实施例讨论在频率域上传输导频信号的情况。
频域的导频信号主要应用于多载波系统如正交频分复用(Orthogonal Frequency Division Multiplexing，OFDM)系统、单载波频分多址(Single-carrier Frequency-Division Multiple Access，SC-FDMA)系统和离散傅里叶变换预编码的正交频分复用(Discrete Fourier Transform-Precoded OFDM，DFT-precoded OFDM)系统等。导频信号可以用于估计信道，估计射频失真的干扰，例如相噪、频偏和同相和正交相位不平衡(In-phase and Quadrature-phase Imbalance，IQI)。导频信号还可以用于其他有同样等效信道信号模型的其他多载波系统，例如通用滤波多载波(Universal Filtered Multi-Carrier，UFMC)系统、广义频分复用(Generalized Frequency Division Multiplexing，GFDM)和单载波频域均衡系统等。
现有的导频序列的设计方案主要分为无射频失真条件下的导频序列的设计和射频失真条件下的导频序列设计。由于实际系统中一般都存在射频失真，本申请实施例应用于射频失真条件下的导频序列设计。现有的射频失真条件下的导频序列的设计方案主要有针对信道+IQI的导频序列设计、针对信道+相位噪声的导频序列设计和针对信道+相位噪声+频偏的导频序列设计等等。但是针对相噪引起的载波间干扰(Inter-Carrier/Inter-sub-Carrier Interference，ICI)和IQI引起的镜像干扰(Mirror Tone Interference，MTI)的导频序列设计则较少。
图1示出了现有的一种导频序列设计方案。该方案对于MTI和ICI对导频序列的影响均未考虑。如图所示，当RFD水平较高时，ICI和/或MTI会严重影响系统性能，导频序列中各位置的信号会受到旁边子载波的干扰(ICI)和镜像干扰(MTI)。导频序列中非零导频和零导频都受到很大干扰，导致等效信道增益的估计不准确，使得系统在现有的导频设计方案下无法正常工作。其中，图中的DC(Direct Current)表示直流子载波。
图2示出了现有的另一种导频序列设计方案。该方案未考虑ICI对导频序列的影响。如图所示，当RFD水平较高时，导频序列中非零导频和零导频都受到很大干扰，使得系 统在现有的导频设计方案下无法正常工作。
图3示出了现有的又一种导频序列设计方案。该方案对于MTI和ICI对导频序列的影响均未考虑。如图所示，接收导频被数据的ICI以及其它导频的MTI破坏，导致信道估计不准确，数据解调性能恶化。
综上所述，现有的导频序列设计方案，要么只考虑镜像干扰(MTI)，要么只考虑载波间干扰(ICI)，或者MTI和ICI的影响均未考虑。因此，当RFD水平较高时，ICI和/或MTI会严重影响系统的性能，使得系统在现有的导频设计方案下无法正常工作。
本申请实施例针对现有方案的以上不足，提出了新的有效的导频序列的设计方案。本申请实施例中导频序列的设计可以分为两种类型。第一类导频序列，如图4所示，该类导频序列所在的OFDM符号的所有有用子载波都用来发送导频(包括非零导频或零导频)。通常，第一类导频序列所在的OFDM符号放在发送帧的最前面，或者插在发送帧的中部，或者穿插在整个发送帧里面。第二类导频序列，如图5所示，在同一个OFDM符号内同时发送数据及导频(包括非零导频或零导频)。如图6所示，第一类导频序列和第二类导频序列还可以结合在一起设计。
为了方便描述，对导频序列设计过程中涉及的参数基概念进行定义。
将OFDM的子载波进行编号，索引0对应直流子载波，较直流子载波频率低的一侧的子载波索引为负，较直流子载波频率高的一侧的子载波索引为正。
子载波间隔为Δf
快速傅里叶变换(Fast Fourier Transformation，FFT)点数NDFT
有效子载波范围：[-NL,NR]
单边明显的ICI扩展长度为κ个子载波
单边明显的MTI扩展长度为ι个子载波
直流子载波右侧(频率高的一侧)第一个有用子载波索引l1，例如l1＝1表示只有直流子载波没有被使用，l1＝2表示有3个子载波未被使用，即直流子载波及其左右各一个子载波未被使用
第n个OFDM符号在直流子载波左侧和右侧非零导频的索引集合分别为
Figure PCTCN2017078618-appb-000001
和
Figure PCTCN2017078618-appb-000002
第n个OFDM符号非零导频的索引集合为
Figure PCTCN2017078618-appb-000003
第n个OFDM符号非零导频的镜像索引集合为JNZPM,n＝-JNZP,n，其中，直流子载波左右对称位置的子载波互为镜像子载波
第n个OFDM符号上第k个数字信道的直流子载波左侧和右侧非零导频的索引集合分别为
Figure PCTCN2017078618-appb-000004
和
Figure PCTCN2017078618-appb-000005
非零导频的索引集合为
Figure PCTCN2017078618-appb-000006
非零导频的镜像索引集合为
Figure PCTCN2017078618-appb-000007
第n个OFDM符号在直流子载波右侧非零导频和零导频的索引集合为
Figure PCTCN2017078618-appb-000008
第n个OFDM符号在直流子载波左侧非零导频和零导频的索引集合为
Figure PCTCN2017078618-appb-000009
归一化的等效信道相干带宽为
Figure PCTCN2017078618-appb-000010
即
Figure PCTCN2017078618-appb-000011
个子载波，其中，
Figure PCTCN2017078618-appb-000012
表示向上取整，对于频域不相关的IQI系统，Wcoh表示信道的相干带宽；对于频域相关的IQI系统，Wcoh表示等效信道(信道+频域相干IQI)的相干带宽。在归一化的等效信道相干带宽内，可以认为信道基本保持不变。
应理解，本申请实施例中，扩展长度是指由于干扰扩展所导致的在频域上的影响范围。具体而言，扩展长度范围内的子载波会对非零导频造成干扰。非零导频会受到旁边所有子载波的干扰，例如对于ICI，离非零导频越近的子载波，对非零导频的干扰越大。例如，ICI扩展长度是指由于ICI扩展所导致的在频域上的影响范围，具体如由于ICI扩展所导致的在频域上影响的子载波的个数。MTI扩展长度是指由于MTI扩展所导致的在频域上的影响范围，具体如由于MTI扩展所导致的在频域上影响的子载波的个数。当然干扰的扩展不仅仅以子载波个数为单位，也可以以其他方式作为单位，本申请实施例对此不作限定。
图7示出了根据本申请实施例提供的传输导频信号的方法的示意性流程图，该方法可以由发送设备执行。如图7所示，该方法包括：
S501，确定导频序列中任意两个相邻的非零导频的导频间隔，所述导频间隔是根据射频失真条件下干扰的扩展长度确定的；
S502，根据所述导频间隔生成所述导频序列，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，所述导频序列的非零导频的子载波对应的镜像子载波为空子载波；
S503，发送所述导频序列。
换而言之，发送设备生成导频序列，所述导频序列中任意两个相邻的非零导频的导频间隔是根据射频失真条件下干扰的扩展长度确定的，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，所述非零导频的子载波对应的镜像子载波为空子载波；发送所述导频序列。
从结果上来看，该方法可以包括：确定导频序列中任意两个相邻的非零导频的导频间隔，所述导频间隔大于或等于1；根据所述导频间隔生成所述导频序列，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，所述导频序列的非零导频的子载波对应的镜像子载波为空子载波；发送所述导频序列。或者，该方法可以包括：生成导频序列，所述导频序列中任意两个相邻的非零导频的导频间隔大于或等于1，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，所述非零导频的子载波对应的镜像子载波为空子载波；发送所述导频序列。
在本申请实施例中，为系统分配非零导频载波的同时，还为系统分配零导频载波， 非零导频的导频间隔设计基于不被不干扰的原则，使非零导频载波和数据受到干扰的影响明显减弱，从而使得系统受射频失真的影响较小，提升系统的性能。
应理解，本申请各实施例中所讨论的干扰主要涉及ICI和MTI，当然当系统中存在其他干扰时也可以以考虑类似ICI和MTI的方式，将其对导频序列设计的影响考虑进来。对应上文，所述扩展长度包括载波间干扰ICI扩展长度和镜像干扰MTI扩展长度。
ICI扩展长度又可以称为ICI扩展因子，MTI扩展长度又可以称为MTI扩展因子。ICI扩展因子和MTI扩展因子可以是单边的也可以是双边的，并且可以根据不同准则选取不同的配置，本申请实施例对此不作限定。
因此，同同时考虑相噪引起ICI以及IQI引起MTI的影响。根据射频失真条件下ICI扩展长度和MTI扩展长度确定导频序列中任意两个相邻的非零导频的导频间隔，导频序列中任意两个相邻的非零导频之间的导频为零导频，由此将ICI和IQI与非零导频错开，使干扰不影响导频子载波，从而提升系统的性能。应理解，本申请实施例主要针对发送设备和接收设备均存在高射频失真的系统，其各个RF通道的射频失真会引起非相干的ICI和MTI。
具体而言，S501确定导频序列中任意两个相邻的非零导频的导频间隔，可以包括：
根据所述射频失真条件下干扰的扩展长度，确定非零导频最小抗干扰距离；
根据所述非零导频最小抗干扰距离，确定所述导频间隔，所述导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述非零导频最小抗干扰距离。
其中，在此之前还可以获取射频失真条件下的干扰的扩展长度。具体到ICI和MTI两种干扰，则为获取射频失真条件下的载波间干扰ICI扩展长度和镜像干扰MTI扩展长度。
具体地，发送导频序列的过程可以如下：
获取射频失真条件下的干扰的扩展长度；
根据所述扩展长度，确定非零导频最小抗干扰距离；
根据所述非零导频最小抗干扰距离，生成导频序列，所述导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述非零导频最小抗干扰距离，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，且非零导频的子载波对应的镜像子载波为空子载波；
发送所述导频序列。
本申请实施例中，根据RFD的水平、信道设置的不同或者系统设置的不同，导频序列的设计参数也有所不同。本申请实施例针对具有频域选择性信道，发送设备和/或接收设备存在RFD的OFDM、SC-FDMA或其他多载波系统提出的导频序列设计方案，包括：用于估计等效信道增益的导频序列的设计方案；用于估计I CI系数和MTI系数的导频序列的设计方案；以及用于估计等效信道增益和估计ICI系数及MTI系数的导频序列的设计方案。
具体地，所述方法可以包括：获取射频失真条件下的载波间干扰ICI扩展长度和镜像干扰MTI扩展长度；根据所述ICI扩展长度和所述MTI扩展长度，确定非零导频最小抗干扰距离；根据所述非零导频最小抗干扰距离，生成导频序列，所述导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述非零导频最小抗干扰距离，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，且非零导频的子载波对应的镜像 子载波为空子载波；发送所述导频序列。
本申请实施例的传输导频信号的方法区别于现有的导频序列的设计方案的地方在于：为系统分配非零导频载波的同时，还为系统分配零导频载波，非零导频的导频间隔设计基于不被不干扰的原则，使非零导频载波和数据受到MTI和ICI的影响明显减弱，从而使得系统受RFD的影响较小，提升系统的性能。
上文已经介绍了本申请实施例涉及的两类导频序列。具体地，本申请实施例的导频序列的设计方案可以分为4组。第一组设计方案为将第一类导频序列，用于估计等效信道增益；第二组设计方案为将第二类导频序列，用于估计ICI系数和MTI系数；第三组设计方案为将第一类导频序列，用于估计等效信道增益和估计ICI系数及MTI系数；第四组设计方案为将第一组设计方案和第二组设计方案结合起来，用于估计等效信道增益和估计ICI系数及MTI系数，成为混合类型的导频序列的设计方案。
下面首先大致介绍本申请实施例中不同场景下导频序列的设计思路。应理解，本申请实施例中可以不使用直流子载波(DC)，将其在图中用虚线标示。
图8、图9和图10示出的为第一组设计方案，用于估计等效信道增益，导频序列覆盖整个有效子载波范围。所述导频间隔使得干扰对非零导频的影响小于第一阈值，所述生成导频序列，包括：根据系统的等效信道相干带宽，生成所述导频序列。本组设计方案，用于估计等效信道增益的场景，其设计使得导频序列最终等效的导频间隔使得干扰对非零导频的影响小于第一阈值，且导频序列最终等效的导频间隔小于或等于系统的等效信道相干带宽。第一阈值可以是根据系统对干扰的容忍程度确定的。具体而言，通过参考系统中存在的干扰的扩展长度可以设计导频间隔，使之符合干扰对非零导频的影响小于第一阈值。图8对应的ICI扩展长度κ＝1，MTI扩展长度ι＝0。图9和图10对应的ICI扩展长度κ＝1，MTI扩展长度ι＝1。
具体而言，由于每一个子载波都会受到周围子载波的载波间干扰(ICI)，以及镜像位置的镜像干扰(MTI)。因此，为了使非零导频不受ICI和MTI扩展的影响，在非零导频之间插入适当数量的零导频，即插入零导频获得的非零导频间的导频间隔使得干扰对非零导频的影响小于一定的阈值，例如第一阈值。换而言之，发送设备在多个导频子载波上分别发送非零导频信号，任意两个相邻的非零导频子载波之间至少有一个空子载波，该空子载波不发送信号，并且非零导频位置的镜像子载波也为一个空子载波。优选地，非零导频的子载波对应的镜像子载波左右分别相邻的子载波也为空子载波(如图9和图10所示)。由此，可以进一步减小MTI对系统性能的影响。
具体地，至少max(κ,2ι+1)个(其中，max(a,b)表示取a和b中值较大的作为输出)零导频被插入非零导频之间，使得ICI和MTI的扩展落入空子载波的位置。max(κ+1,2ι+2)称为估计等效信道增益非零导频的最小抗干扰距离，也可以称为第一非零导频最小抗干扰距离，用IFDmain表示。
其中，IFDmain＝max(κ+1,2ι+2)是一种可选的实现方式，其镜像子载波占一个子载波，MTI的单边扩展长度为ι，双边扩展长度为为2ι，因此需要的空载波个数为2ι+1，非零导频的导频间隔从MTI角度看需要大于或等于2ι+2。
在一个可选的实施例中，非零导频的子载波对应的镜像子载波左右分别相邻的子载 波也可以为空子载波。
相应地，所述导频序列用于估计等效信道增益，所述ICI扩展长度为κ个子载波，所述MTI扩展长度为ι个子载波，根据所述ICI扩展长度和所述MTI扩展长度，确定非零导频最小抗干扰距离，可以包括：
根据所述ICI扩展长度为κ个子载波和所述MTI扩展长度为ι个子载波，确定用于估计等效信道增益的第一非零导频最小抗干扰距离IFDmain＝max(κ+1,2ι+2)。
继而，根据系统的等效信道相干带宽
Figure PCTCN2017078618-appb-000013
和第一非零导频最小抗干扰距离IFDmain，可以生成导频序列。如果非零导频的导频间隔小于或等于等效信道相干带宽，由于在信道相干带宽内信道基本不变，因此，通过一个符号可以满足信道估计的需求。否则，需要多个导频符号进行联合估计，使得联合后的相邻非零导频间隔小于或等于等效信道相干带宽。
图11和图12示出的为第二组设计方案和第三组设计方案，用于估计ICI系数和MTI系数，或用于估计等效信道增益及估计ICI系数和MTI系数。图11对应的ICI扩展长度κ＝1，MTI扩展长度ι＝0。图12对应的ICI扩展长度κ＝1，MTI扩展长度ι＝1。
具体地，可以在非零导频之间插入2κ+2ι+1个零导频，使得非零导频的ICI和MTI被减弱，并且不受ICI和MTI扩展的影响。2κ+2ι+2称为抗ICI和MTI的非零导频最小抗干扰距离，也可以称为第二非零导频最小抗干扰距离，用IFDICI,MTI表示。
第二组设计方案和第三组设计方案与第一组设计方案的差别在于，第一组设计方案中导频间隔的选择只需要保证ICI扩展和MTI扩展不干扰非零导频，ICI和MTI可能会重合。而第二组设计方案和第三组设计方案中导频间隔的选择原则除了保证ICI扩展和MTI扩展不干扰非零导频，还需要满足ICI扩展和MTI扩展之间互相不干扰，这样才能较准确的估计出ICI及MTI。因此，以导频间隔等于非零导频最小抗干扰距离来设计导频序列时，第二组设计方案和第三组设计方案的非零导频的导频间隔大于第二组设计方案和第三组设计方案。以导频间隔大于非零导频最小抗干扰距离来设计导频序列时，第二组设计方案和第三组设计方案的非零导频的导频间隔大于或等于第二组设计方案和第三组设计方案。
相应地，所述导频序列用于估计射频失真条件下的至少两种干扰，所述导频间隔使得所述至少两种干扰对非零导频的影响小于第一阈值，并且所述导频间隔使得所述至少两种干扰相互之间的影响小于第二阈值。第二阈值可以是根据系统对干扰的容忍程度确定的。具体而言，通过参考系统中存在的干扰的扩展长度可以设计导频间隔，使之符合干扰相互之间的影响小于第二阈值。
第二组设计方案和第三组设计方案的区别在于，第二组设计方案用于估计ICI系数和MTI系数，第三组设计方案用于估计等效信道增益及估计ICI系数和MTI系数。第二组设计方案中在发送所述导频序列的符号上，还发送数据信号。相应地，发送导频序列，可以包括：在符号上发送该导频序列；方法500还包括：在该符号上还发送数据信号。
针对第二组设计方案和第三组设计方案，所述根据所述ICI扩展长度和所述MTI扩展长度，确定非零导频最小抗干扰距离，可以包括：
根据所述ICI扩展长度为κ个子载波和所述MTI扩展长度为ι个子载波，确定用于估计ICI和MTI的第二非零导频最小抗干扰距离IFDICI,MTI＝2(κ+ι+1)。
图13示出了利用本申请实施例的导频序列设计(图11的设计)下，RFD对各个子载波的影响的示意图。由图13可以看出，非零导频基本未受到来自其他导频的ICI和MTI的影响，从而可以用于估计等效信道增益；零导频则用于传输ICI和MTI的信息，从而可以用于估计ICI系数和MTI系数。
第四组设计方案可以将第一组设计方案和第二组设计方案相结合。此时，所述导频序列包括第一类导频序列和第二类导频序列，所述第一类导频序列用于估计等效信道增益，所述第一类导频序列中任意两个相邻的非零导频的导频间隔为第一导频间隔，所述第二类导频序列用于估计射频失真条件下的至少两种干扰，所述第二类导频序列中任意两个相邻的非零导频的导频间隔为第二导频间隔，所述根据所述导频间隔生成所述导频序列，包括：
生成所述第一类导频序列，所述第一类导频序列根据所述第一导频间隔和系统的等效信道相干带宽生成，所述第一导频间隔使得干扰对非零导频的影响小于第一阈值；
生成所述第二类导频序列，所述第二类导频序列根据所述第二导频间隔生成，所述第二类导频序列中任意两个相邻的非零导频的第二导频间隔使得干扰对非零导频的影响小于第一阈值，并且所述第二导频间隔使得所述至少两种干扰相互之间的影响小于第二阈值；
所述发送所述导频序列，包括：
在第一类符号上发送所述第一类导频序列；
在第二类符号上发送所述第二类导频序列。
或者，换而言之，所述导频序列包括第一类导频序列和第二类导频序列，所述第一类导频序列用于估计等效信道增益，所述第一类导频序列中任意两个相邻的非零导频的导频间隔为第一导频间隔，所述第二类导频序列用于估计射频失真条件下的至少两种干扰，所述第二类导频序列中任意两个相邻的非零导频的导频间隔为第二导频间隔，所述根据所述导频间隔生成所述导频序列，包括：生成所述第一类导频序列，所述第一类导频序列根据系统的等效信道相干带宽生成，所述第一导频间隔使得干扰对非零导频的干扰小于第一阈值；生成所述第二类导频序列，所述第二类导频序列中任意两个相邻的非零导频的第二导频间隔使得干扰对非零导频的影响小于第一阈值，并且所述第二导频间隔使得所述至少两种干扰相互之间的影响小于第二阈值；所述发送所述导频序列，包括：在第一类符号上发送所述第一类导频序列；在第二类符号上发送所述第二类导频序列。
其中，所述导频序列用于估计等效信道增益，以及用于估计ICI和MTI，所述ICI扩展长度为κ个子载波，所述MTI扩展长度为ι个子载波，根据所述ICI扩展长度和所述MTI扩展长度，确定非零导频最小抗干扰距离，可以包括：
根据所述ICI扩展长度为κ个子载波和所述MTI扩展长度为ι个子载波，确定用于估计等效信道增益的第一非零导频最小抗干扰距离IFDmain＝max(κ+1,2ι+2)；
根据所述ICI扩展长度为κ个子载波和所述MTI扩展长度为ι个子载波，确定用于估计ICI和MTI的第二非零导频最小抗干扰距离IFDICI,MTI＝2(κ+ι+1)。
应理解，本申请各实施例中，形成导频序列可以有多种，其中一种为导频序列由多个基本导频单元级联生成，所述基本导频单元中包括一个非零导频。具体在下文中的例子中说明。
下面对各个导频序列设计方案进行详细的介绍。
第一组设计方案可以详细分为以下几种场景。其中一种场景为系统具有单数字通道，根据所述非零导频最小抗干扰距离，生成导频序列，可以包括：如果所述第一非零导频最小抗干扰距离IFDmain小于或等于等效信道相干带宽，在一个符号上生成所述导频序列，所述导频序列中的任意两个相邻的非零导频的导频间隔小于或等于所述等效信道相干带宽，且大于或等于所述第一非零导频最小抗干扰距离。
具体而言，本申请实施例针对具有单数字通道(即只有1个数字模拟转换(Digital to Analog Convert，DAC)和模拟数字转换(Analog to Digital convert，ADC)通道)的系统。归一化的等效信道相干带宽为
Figure PCTCN2017078618-appb-000014
的场景下，在一个符号上生成导频序列，非零导频索引集合可以表示为：
Figure PCTCN2017078618-appb-000015
或
Figure PCTCN2017078618-appb-000016
其中，导频间隔可以设置为D＝IFDmain＝max(κ+1,2ι+2)，
Figure PCTCN2017078618-appb-000017
(即非零导频所在子载波的镜像位置的子载波为空子载波)。此外，当
Figure PCTCN2017078618-appb-000018
G为非负整数时，对任意满足0≤g≤G的整数g，可以设置D＝IFDmain+g，本申请实施例对此不作限定。
图14为本申请实施例的一个具体的例子，其中，κ＝2，ι＝0，D＝IFDmain＝3,l1＝1，NL和NR均为84。因此，直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000019
和
Figure PCTCN2017078618-appb-000020
在本例子中，不使用直流子载波，直流子载波在图中用虚线表示。从图14中可以看出，非零导频与ICI的扩展及MTI的扩展是分开的。在本例子中，非零导频在有效频带上是等间隔分布的，并且任意两个相邻的非零导频的导频间隔不大于等效信道相干带宽，保证了频域选择性信道增益的估计的可靠性。
此外，导频序列中的任意两个相邻的非零导频的导频间隔大于或等于第一非零导频最小抗干扰距离IFDmain即可，并不要求非零导频在有效频带上是等间隔分布的。在本申请所有具体的例子中，直流子载波都不使用，并在图中用虚线表示，但本申请实施例对是否使用直流子载波不作限定，文中他处不再赘述。
其中另一种场景为系统具有单数字通道，根据所述非零导频最小抗干扰距离，生成导频序列，可以包括：如果所述第一非零导频最小抗干扰距离IFDmain大于所述等效信道相干带宽，在M个符号上生成M个导频序列，所述导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述第一非零导频最小抗干扰距离，所述M个导频序列中的 任意两个导频序列的非零导频对应的子载波不同，其中，M为对IFDmain/等效信道相干带宽上取整。
具体而言，本申请实施例针对具有单数字通道的系统。归一化的等效信道相干带宽为
Figure PCTCN2017078618-appb-000021
的场景下，该数字通道需在连续的M个符号上生成并发送导频序列，其中，M为对IFDmain/等效信道相干带宽上取整，即
Figure PCTCN2017078618-appb-000022
第一个符号(m＝1)上的导频序列的设计可以沿用上一例子(图14)中的设计。基于符号m＝1上的非零导频索引集合，可以确定符号m＝2,...,M上的非零导频索引集合。第m个导频OFDM符号的非零导频索引集合可以表示为：
Figure PCTCN2017078618-appb-000023
如果
Figure PCTCN2017078618-appb-000024
或
Figure PCTCN2017078618-appb-000025
如果
Figure PCTCN2017078618-appb-000026
其中，D如图14的例子所定义，β的选择满足
Figure PCTCN2017078618-appb-000027
表示向下取整。
图15为本申请实施例的一个具体的例子，其中，κ＝2，ι＝0，D＝IFDmain＝3,
Figure PCTCN2017078618-appb-000028
l1＝1，NL和NR均为84。因此，在符号1上(即m＝1的符号上)直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000029
和
Figure PCTCN2017078618-appb-000030
在符号2上(即m＝2的符号上)直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000031
和
Figure PCTCN2017078618-appb-000032
两个符号上两个导频序列的非零导频对应的子载波不同，因为本例子中
Figure PCTCN2017078618-appb-000033
因此需要使用两个符号上的导频序列联合进行等效信道增益的估计。
其中另一种场景为系统具有K个数字通道，其中，K大于或等于2，根据所述非零导频最小抗干扰距离，生成导频序列，可以包括：如果所述第一非零导频最小抗干扰距离IFDmain的K倍小于或等于等效信道相干带宽，在一个符号上生成K个导频序列，所述K个导频序列中的每个导频序列中任意两个相邻的非零导频的导频间隔小于或等于所述等效信道相干带宽，且大于或等于所述第一非零导频最小抗干扰距离，所述K个导频序列中的任意两个导频序列的非零导频对应的子载波不同。
具体而言，本申请实施例针对具有K个数字通道的系统。归一化的等效信道相干带宽为
Figure PCTCN2017078618-appb-000034
的场景下，在一个符号上生成并发送导频序列。该符号上 的导频序列的设计可以类似于图14的例子中的设计。该导频OFDM符号的非零导频索引集合可以表示为：
Figure PCTCN2017078618-appb-000035
以及
Figure PCTCN2017078618-appb-000036
其中，k＝2,3,...K；或
Figure PCTCN2017078618-appb-000037
以及
Figure PCTCN2017078618-appb-000038
其中，k＝2,3,...K。
其中，D＝IFDmain＝max(κ+1,2ι+2)，D'＝KD，
Figure PCTCN2017078618-appb-000039
Figure PCTCN2017078618-appb-000040
和
Figure PCTCN2017078618-appb-000041
即所有通道所有非零导频所在子载波的镜像位置都为空子载波。此外，当
Figure PCTCN2017078618-appb-000042
G为非负整数时，对任意满足0≤g≤G的整数g，可以设置D＝IFDmain+g，本申请实施例对此不作限定。
图16为本申请实施例的一个具体的例子，其中，κ＝2，ι＝0，D＝IFDmain＝3，l1＝1，NL和NR均为84，K＝2。两个数字通道采用同一个符号发送导频序列。为了表达的清晰性，将对两个数字通道分开示意。对于第一个数字通道，直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000043
和
Figure PCTCN2017078618-appb-000044
对于第二个数字通道，直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000045
和
Figure PCTCN2017078618-appb-000046
从图16中可以看出，非零导频与ICI扩展及MTI扩展是分开的。在本例子中，非零导频在有效频带上是等间隔分布的，并且任意两个相邻的非零导频的导频间隔不大于等效信道相干带宽，保证了频域选择性信道增益的估计的可靠性。
其中另一种场景为系统具有K个数字通道，其中，K大于或等于2，根据所述非零导频最小抗干扰距离，生成导频序列，可以包括：如果所述第一非零导频最小抗干扰距离IFDmain的K倍大于所述等效信道相干带宽，且所述第一非零导频最小抗干扰距离IFDmain小于或等于所述等效信道相干带宽，在N个符号上生成K个导频序列，其中，N小于或等于K，第n个符号上生成Kn个导频序列，n的取值为1,2,...,N，Kn小于或等于K0，K0为对等效信道相干带宽/IFDmain下取整，所述第n个符号上的Kn个导频序列中的每个导频序列中任意两个相邻的非零导频的导频间隔小于或等于所述等效信道相干带宽，且大于或等于所述第一非零导频最小抗干扰距离，所述第n个符号上的Kn个导频 序列中的任意两个导频序列的非零导频对应的子载波不同。
具体而言，本申请实施例针对具有K个数字通道的系统。归一化的等效信道相干带宽满足
Figure PCTCN2017078618-appb-000047
的场景下，在N个符号上生成K个导频序列。首先确定每个符号上可以承载的数字通道的导频的最大值K0，K0为对等效信道相干带宽/IFDmain下取整，即
Figure PCTCN2017078618-appb-000048
定义正整数集{Kn}，其中，Kn≤K0，且K1+K2+...+KN＝K。本申请实施例需要N个符号发送导频序列，符号n(Sym n)承载Kn个数字通道的导频序列。所述第n个符号上的Kn个导频序列中的每个导频序列中任意两个相邻的非零导频的导频间隔小于或等于所述等效信道相干带宽，且大于或等于所述第一非零导频最小抗干扰距离，所述第n个符号上的Kn个导频序列中的任意两个导频序列的非零导频对应的子载波不同。
在本例子中，从节省开销的角度，N越小越好，并且可以尽量将导频序列集中在序号较小的符号上，例如Kn≤Kn-1。具体地，如K0＝2，K＝5，则可以有N＝3，K1＝2,K2＝2,K3＝1。
图17为本申请实施例的一个具体的例子，其中，κ＝2，ι＝0，K0＝2，
Figure PCTCN2017078618-appb-000049
K＝4，D＝IFDmain＝3，l1＝1，NL和NR均为84，N＝2。对于任一个符号(例如Sym n)，其导频序列设计可以参考图16的例子的设计，其中，K0＝2，K＝4，K1＝2，K2＝2。对于第一个符号，可以承载2个通道的导频序列，其中，第1个通道在直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000050
和
Figure PCTCN2017078618-appb-000051
第2个通道在直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000052
和
Figure PCTCN2017078618-appb-000053
对于第二个符号，可以承载2个通道的导频序列，其中，第3个通道在直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000054
和
Figure PCTCN2017078618-appb-000055
第4个通道在直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000056
和
Figure PCTCN2017078618-appb-000057
其中另一种场景为系统具有K个数字通道，其中，K大于或等于2，根据所述非零导频最小抗干扰距离，生成导频序列，可以包括：如果所述第一非零导频最小抗干扰距离IFDmain大于所述等效信道相干带宽，在MK个符号上生成MK个导频序列，每个数字通道在M个符号上生成M个导频序列，其中，M为对IFDmain/等效信道相干带宽 上取整，每个导频序列中任意两个相邻的非零导频的导频间隔大于或等于所述第一非零导频最小抗干扰距离，每个数字通道的所述M个导频序列中的任意两个导频序列的非零导频对应的子载波不同。
具体而言，本申请实施例针对具有K个数字通道的系统。归一化的等效信道相干带宽满足
Figure PCTCN2017078618-appb-000058
的场景下，每个数字通道需在连续的M个符号上生成并发送导频序列，其中，M为对IFDmain/等效信道相干带宽上取整，即
Figure PCTCN2017078618-appb-000059
因此，K个数字通道需要在MK个符号上生成MK个导频序列。每个数字通道的设计可以类似于图15的例子。
图18为本申请实施例的一个具体的例子，其中，κ＝2，ι＝0，
Figure PCTCN2017078618-appb-000060
K＝2，D＝IFDmain＝3，l1＝1，NL和NR均为84，M＝2。对于第1个数字通道，在符号1上直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000061
和
Figure PCTCN2017078618-appb-000062
在符号2上直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000063
和
Figure PCTCN2017078618-appb-000064
对于第2个数字通道，在符号3上直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000065
和
Figure PCTCN2017078618-appb-000066
在符号4上直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000067
和
Figure PCTCN2017078618-appb-000068
第二组设计方案中，第二类导频序列用于估计ICI系数和MTI系数，在一个符号上同时发送导频(包括非零导频和空导频)和数据，即在发送所述导频序列的符号上，还发送数据信号。为了较准确的估计ICI系数及MTI系数，导频间隔的选择原则为保证ICI扩展和MTI扩展不干扰非零导频，同时满足ICI扩展和MTI扩展之间互相不干扰，因此需要在非零导频之间插入2κ+2ι+1个空导频。
在本申请实施例中，导频序列可以由基本导频单元级联生成，所述基本导频单元中包括一个非零导频，两个所述基本导频单元级联时，两个所述基本导频单元中的两个非零导频的导频间隔大于或等于所述第二非零导频最小抗干扰距离。
具体地，可以定义两种基本导频单元，基本导频单元一：p1＝[01×κ,1,01×κ,01×2ι+1]，基本导频单元二：p2＝[01×2ι+1,01×κ,1,01×κ]，在基本导频单元中，1代表非零导频，0代表空导频。当然还可以对基本导频单元进行其他的设计，例如基本导频单元中可以包括更多个数的0，即零导频，本申请实施例对基本导频单元的形式不作限定。在下文的描述中可以任选一种基本导频单元，描述时以符号p进行说明。
第二组设计方案可以详细分为以下几种场景。其中一种场景为系统具有单数字通道，根据所述非零导频最小抗干扰距离，生成导频序列，可以包括：如果所述导频序列 的长度小于或等于一个符号上导频可用信道带宽，在一个符号的直流载波的左侧的连续子载波组和右侧的连续子载波组上分别生成包括V个非零导频的导频序列，所述导频序列中任意两个相邻的非零导频的导频间隔大于或等于所述第二非零导频最小抗干扰距离，其中，V大于1。V的大小可以根据符号上导频可用信道带宽确定。V越大，对干扰的估计越准确。
针对单数字通道系统的场景。假设导频符号有2V个非零导频，直流子载波的左边和右边分别有V个，分别用
Figure PCTCN2017078618-appb-000069
表示，其中
Figure PCTCN2017078618-appb-000070
表示克罗内克(Kronecker)积，p为上文中的基本导频单元。该设计保证了非零导频之间有2κ+2ι+1个空导频的需求。直流子载波右边的非零导频集合用pR表示，可以从
Figure PCTCN2017078618-appb-000071
获取，直流子载波左边的非零导频集合用pL表示，可以从
Figure PCTCN2017078618-appb-000072
获取。对于基本导频单元一，有
Figure PCTCN2017078618-appb-000073
对于基本导频单元二，有
Figure PCTCN2017078618-appb-000074
通常，pR和pL可以放在任何两个满足以上条件的连续子载波组上。如果最左边或最右边的空导频01×κ与边带空子载波或者直流子载波旁边的空子载波相连，那么该空导频01×κ可以省略。
图19为本申请实施例的一个具体的例子，其中κ＝2，ι＝0，2V＝4，基本导频单元采用基本导频单元一。因此，直流子载波左侧的非零导频的集合为
Figure PCTCN2017078618-appb-000075
基本导频单元所占用的位置的集合为
Figure PCTCN2017078618-appb-000076
直流子载波右侧的非零导频的集合为
Figure PCTCN2017078618-appb-000077
基本导频单元所占用的位置的集合为
Figure PCTCN2017078618-appb-000078
如此设计使得非零导频与ICI扩展及MTI扩展被减弱，可以保证数据和导频不受ICI和MTI的干扰。
其中另一种场景为系统具有K个数字通道，其中，K大于或等于2，所述根据所述非零导频最小抗干扰距离，生成导频序列，可以包括：如果K个数字通道的导频序列的总长度小于或等于一个符号上导频可用信道带宽，在一个符号上生成K个导频序列，所述K个导频序列中每个导频序列中任意两个相邻的非零导频的导频间隔大于或等于所述第二非零导频最小抗干扰距离，所述K个导频序列中的任意两个导频序列的非零导频对应的子载波不同。
针对K个具有数字通道的系统，在满足条件2(κ+ι+1)VK+2κ<min(NL,NR)或2(κ+ι+1)VK+K+2κ<min(NL,NR)，符号上同时发送有数据的场景下，对于每一个数字通道的导频序列，都可以采用类似上述2V个非零导频的设计(即图19的例子的设计)。
定义其中p代表两种基本导频单元的任意一种。非零导频集合pR,(k)和pL,(k)分别用
Figure PCTCN2017078618-appb-000080
和
Figure PCTCN2017078618-appb-000081
表示，对于基本导频单元一有
Figure PCTCN2017078618-appb-000082
对于基本导频单元二有
Figure PCTCN2017078618-appb-000083
导频向量{pR,(k)}可以是[pR,(1),pR,(2),...,pR,(K)]的级联，也可以是加入若干个空子载波(例如一个空子载波)的级联如[pR,(1),0,pR,(2),0,...,pR,(K-1),0,pR,(K)]。
对于不同的数字通道，其非零导频索引集合有以下相关关系：
Figure PCTCN2017078618-appb-000084
(基本导频单元直接级联的情况)，或
Figure PCTCN2017078618-appb-000085
(基本导频单元间加入一个空子载波的情况)。直流子载波右边的非零导频集合用pR表示，可以从
Figure PCTCN2017078618-appb-000086
获取，直流子载波左边的非零导频集合用pL表示，可以从
Figure PCTCN2017078618-appb-000087
获取。对于基本导频单元一，有
Figure PCTCN2017078618-appb-000088
对于基本导频单元二，有
Figure PCTCN2017078618-appb-000089
应理解，这里n表示符号n，在本申请实施例中仅占用一个符号，下角标处的n可以省略。
如果最左边或最右边的空导频01×κ与边带空子载波或者直流子载波旁边的空子载波相连，那么该空导频01×κ可以省略。
图20为本申请实施例的一个具体的例子，其中κ＝2，ι＝0，K＝2个数字信道，每个数字通道包含2V＝4个非零导频，两个数字通道的导频之间采用直接级联的模式。两个数字通道在时间上使用相同的导频符号。因此，针对第一个数字通道，直流子载波左侧的非零导频的集合为
Figure PCTCN2017078618-appb-000090
基本导频单元所占用的位置的集合为
Figure PCTCN2017078618-appb-000091
直流子载波右侧的非零导频的集合为
Figure PCTCN2017078618-appb-000092
基本导频单元所占用的位置的集合为
Figure PCTCN2017078618-appb-000093
针对第二个数字通道，直流子载波左侧的非零导频的集合为
Figure PCTCN2017078618-appb-000094
基本导频单元所占用的位置的集合为
Figure PCTCN2017078618-appb-000095
直流子载波右侧的非零导频的集合为
Figure PCTCN2017078618-appb-000096
基本导频单元所占用的位置的集合为
Figure PCTCN2017078618-appb-000097
如此设计使得非零导频与ICI扩展及MTI扩展被减弱，可以保证数据和导频不受ICI和MTI的干扰。
在本场景的另外一种情况下，即仍是在针对K个数字通道系统，一个导频符号可以满足所有K个数字通道导频的场景中，符号上不发送数据的情况下。假设每个数字通道使用2V个非零导频。本申请实施例应用于以下条件：2(κ+ι+1)VK<min(NL,NR)(基本导频单元直接级联的情况)，或2(κ+ι+1)VK+K<min(NL,NR)(基本导频单元间加入空子载波的情况)。具体设计与发送数据的情况相类似。
图21为本申请实施例的一个具体的例子，其中κ＝2，ι＝0，K＝3个数字信道，每个数字通道包含2V＝8个非零导频，不同数字通道的导频向量{pR,(k),pL,(k)}通过5个空载波分离开。因此，针对第一个数字通道，直流子载波左侧的非零导频的集合为
Figure PCTCN2017078618-appb-000098
基本导频单元所占用的位置的集合为pL,(1)；直流子载波右侧的非零导频的集合为
Figure PCTCN2017078618-appb-000099
基本导频单元所占用的位置的集合为pR,(1)。针对第二个数字通道，直流子载波左侧的非零导频的集合为
Figure PCTCN2017078618-appb-000100
基本导频单元所占用的位置的集合为pL,(2)；直流子载波右侧的非零导频的集合为
Figure PCTCN2017078618-appb-000101
基本导频单元所占用的位置的集合为pR,(2)。针对第三个数字通道，直流子载波左侧的非零导频的集合为
Figure PCTCN2017078618-appb-000102
基本导频单元所占用的位置的集合为pL,(3)；直流子载波右侧的非零导频的集合为
Figure PCTCN2017078618-appb-000103
基本导频单元所占用的位置的集合为pR,(3)。如此设计使得非零导频与ICI扩展及MTI扩展被减弱，可以保证数据和导频不受ICI和MTI的干扰。
其中另一种场景为系统具有K个数字通道，其中，K大于或等于2，所述根据所述非零导频最小抗干扰距离，生成导频序列，可以包括：如果K个数字通道的导频序列的总长度大于一个符号上导频可用信道带宽，在T个符号上生成K个导频序列，其中，T小于或等于K，第t个符号的导频可用信道带宽上生成Kt个导频序列，t的取值为1,2,...,T，Kt小于或等于K'0，一个符号最多可传输K'0个数字通道的导频序列，所述K个导频序列中每个导频序列中任意两个相邻的非零导频的导频间隔大于或等于所述第二非零导频最小抗干扰距离，所述第t个符号上的Kt个导频序列中的任意两个导频序列的非零导频对应的子载波不同。
本申请实施例是针对具有K个数字通道的系统，一个导频符号无法满足所有K个数字通道导频的场景。假设每个数字通道使用2V个非零导频，1个导频符号最多可以为K'0个数字通道提供导频，其他子载波用来传输数据，因此，共需要
Figure PCTCN2017078618-appb-000104
个符号承载导频，其中第t个符号为Kt数字通道提供导频，K1+K2+...+KT＝K，Kt≤K'0。对于每一个导频符号，采用图20类似的设计。
图22为本申请实施例的一个具体的例子，其中κ＝2，ι＝0，K＝4个数字信道，每个数字通道包含2V＝4个非零导频，每个导频符号为2个数字通道的设置导频。每个 数字通道在符号上导频序列的设计如图22所示，在符号1上设计第一个数字通道的导频序列，直流子载波左侧的非零导频的集合为
Figure PCTCN2017078618-appb-000105
基本导频单元所占用的位置的集合为
Figure PCTCN2017078618-appb-000106
直流子载波右侧的非零导频的集合为
Figure PCTCN2017078618-appb-000107
基本导频单元所占用的位置的集合为
Figure PCTCN2017078618-appb-000108
在符号1上设计第二个数字通道的导频序列，直流子载波左侧的非零导频的集合为
Figure PCTCN2017078618-appb-000109
基本导频单元所占用的位置的集合为
Figure PCTCN2017078618-appb-000110
直流子载波右侧的非零导频的集合为
Figure PCTCN2017078618-appb-000111
基本导频单元所占用的位置的集合为
Figure PCTCN2017078618-appb-000112
在符号2上设计第三个数字通道的导频序列，直流子载波左侧的非零导频的集合为
Figure PCTCN2017078618-appb-000113
基本导频单元所占用的位置的集合为
Figure PCTCN2017078618-appb-000114
直流子载波右侧的非零导频的集合为
Figure PCTCN2017078618-appb-000115
基本导频单元所占用的位置的集合为
Figure PCTCN2017078618-appb-000116
在符号2上设计第四个数字通道的导频序列，直流子载波左侧的非零导频的集合为
Figure PCTCN2017078618-appb-000117
基本导频单元所占用的位置的集合为
Figure PCTCN2017078618-appb-000118
直流子载波右侧的非零导频的集合为
Figure PCTCN2017078618-appb-000119
基本导频单元所占用的位置的集合为
Figure PCTCN2017078618-appb-000120
如此设计使得非零导频与ICI扩展及MTI扩展被减弱，可以保证数据和导频不受ICI和MTI的干扰。
第三组设计方案中，第一类导频序列用于估计等效信道增益以及估计ICI系数和MTI系数，导频(包括非零导频和空导频)覆盖整个有效子载波范围。导频间隔的选择原则为保证ICI扩展和MTI扩展不干扰非零导频，同时满足ICI扩展和MTI扩展之间互相不干扰，因此需要在非零导频之间插入2κ+2ι+1个空导频，这样，非零导频的ICI和MTI被减弱，并且不受ICI扩展和MTI扩展的影响。换而言之，发送设备在多个子载波上分别发送非零导频信号，任意两个相邻非零导频子载波之间至少有一个空子载波，该空子载波不发送信号，并且非零导频的子载波对应的镜像子载波也为一个空子载波。
如果非零导频间的导频间隔小于或等于等效信道的相干带宽，由于在信道相干带宽内，信道基本不变，因此，通过一个符号可以满足信道估计的需求。否则，需要多个符号进行联合估计，使得联合后的相邻非零导频间隔小于或等于等效信道的相干带宽。
可以理解，第三组设计方案可以与第一组设计方案完全类似，只是将第一组设计方案中的第一非零导频最小抗干扰距离IFDmain用第二非零导频最小抗干扰距离IFDICI,MTI代替。
例如，具有单数字通道的系统，所述根据所述非零导频最小抗干扰距离，生成导频序列，包括：
如果所述第二非零导频最小抗干扰距离IFDICI,MTI小于或等于等效信道相干带宽，在一个符号上生成所述导频序列，所述导频序列中的任意两个相邻的非零导频的导频间隔小于或等于所述等效信道相干带宽，且大于或等于所述第二非零导频最小抗干扰距离；
如果所述第二非零导频最小抗干扰距离IFDICI,MTI大于所述等效信道相干带宽，在U个符号上分别生成U个导频序列，所述U个导频序列中的任意两个导频序列的非零导频对应的子载波不同，所述U个导频序列中的每个导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述第二非零导频最小抗干扰距离其中，U为对IFDICI,MTI/等效信道相干带宽上取整。
举一个具体的例子，本申请实施例针对单数字通道系统，归一化等效信道相干带宽
Figure PCTCN2017078618-appb-000121
IFDICI,MTI＝2(κ+ι+1)，ICI系数和MTI系数为时不变或时慢变的场景。对于非零导频索引集合JNZP，定义ICI对应的子载波索引集合为JICI＝{JNZP-κ,JNZP-κ+1,…,JNZP+κ}和MTI对应的子载波索引集合JMTI＝Jmirror＝{JNZPM-ι,JNZPM-ι+1,...,JNZPM+ι}。其中，导频设计需要满足
Figure PCTCN2017078618-appb-000122
本设计可以应用基本导频单元p来设计(包括基本导频单元一p1或基本导频单元二p2)。对于直流子载波右边的导频设计，可以从第l1(或l1-1)个子载波开始重复p，直到最后一个有效子载波NR。同理，直流子载波左边的导频设计，可以从第-l1+β个子载波开始重复p，直到最后一个有效子载波-NL。其中，对于第一类导频序列的导频设计，有
Figure PCTCN2017078618-appb-000123
对于第二类导频序列的导频设计，任何没有使用的子载波都看作空子载波。
图23为本申请实施例的一个具体的例子，其中，κ＝2，ι＝0，NL和NR均为84，
Figure PCTCN2017078618-appb-000124
可以发现，非零导频与ICI扩展及MTI扩展被减弱，并且非零导频间距IFDICI,MTI＝6小于有效信道相干带宽。直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000125
和
Figure PCTCN2017078618-appb-000126
针对具有单数字通道的系统，有另外一种设计方案，该方案属于第四组设计方案。具体方法是根据所述非零导频最小抗干扰距离，生成导频序列，包括：在第一类符号上生成第一类导频序列，所述第一类导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述第一非零导频最小抗干扰距离；在所述第一类符号后的第二类符号上生成第 二类导频序列，所述第二类导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述第二非零导频最小抗干扰距离。
具体地，如果所述第一非零导频最小抗干扰距离IFDmain小于或等于等效信道相干带宽，在一个第一类符号上生成一个第一类导频序列，所述第一类导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述第一非零导频最小抗干扰距离，且小于或等于所述等效信道相干带宽；
如果所述第一非零导频最小抗干扰距离IFDmain大于所述等效信道相干带宽，在Y个符号上生成Y个第一类导频序列，所述第一类导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述第一非零导频最小抗干扰距离，所述Y个第一类导频序列中的任意两个第一类导频序列的非零导频对应的子载波不同，其中，Y为对IFDmain/等效信道相干带宽上取整；
在所述第一类符号后的第二类符号上生成第二类导频序列，所述第二类导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述第二非零导频最小抗干扰距离。
应理解，本申请实施例适用于时不变或时慢变的ICI和MTI的场景及即时变化的ICI和MTI的场景时，设计也可以有所不同。两种场景下导频序列设计的不同之处在于一个传输帧内传输第二类导频序列的符号的个数。对于时时不变或时慢变的ICI和MTI场景，传输第一类导频序列的符号后面只需要一个传输第二类导频序列的符号；而对于即时变化的ICI和MTI的场景，即符号之间ICI系数和MTI系数变化明显的场景，传输第一类导频序列的符号后面的每一个符号都需要设置为传输第二类导频序列的符号。
这是由于如果信道变化很慢，可以认为在一个传输帧中所有符号的等效信道是不变的，只需要通过一个符号就能计算出ICI和MTI，可以用同样的ICI和MTI对所有符号进行估计和补偿；如果信道变化很快，每个符号的信道都是时变的，所以每个符号都要分别进行ICI和MTI的估计和补偿。
图24示出了本申请实施例的一个具体的例子，其中，κ＝2，ι＝0，
Figure PCTCN2017078618-appb-000127
K＝1个数字通道，NL和NR均为84。第一个符号(符号1)为基于类似于图14的例子设计的传输第一类导频序列的符号，其中D＝IFDmain＝3,l1＝1，符号1上直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000128
和
Figure PCTCN2017078618-appb-000129
第二个符号(符号2)为基于类似于图19的例子设计的传输第二类导频序列的符号，其中2V＝4个非零导频，符号2上直流子载波左侧的非零导频的集合为
Figure PCTCN2017078618-appb-000130
基本导频单元所占用的位置的集合为
Figure PCTCN2017078618-appb-000131
直流子载波右侧的非零导频的集合为
Figure PCTCN2017078618-appb-000132
基本导频单元所占用的位置的集合为
Figure PCTCN2017078618-appb-000133
第三组设计方案的一种场景为系统具有K个数字通道，其中，K大于或等于2，所述根据所述非零导频最小抗干扰距离，生成导频序列，可以包括：如果所述第二非零导频最小抗干扰距离IFDICI,MTI的K倍小于或等于等效信道相干带宽，在一个符号上生成K个导频序列，所述K个导频序列中的每个导频序列中任意两个相邻的非零导频的导频间隔小于或等于所述等效信道相干带宽，且大于或等于所述第二非零导频最小抗干扰距离，所述K个导频序列中的任意两个导频序列的非零导频对应的子载波不同。
本申请实施例针对具有K个数字通道的系统，归一化等效信道相干带宽
Figure PCTCN2017078618-appb-000134
ICI系数和MTI系数为时不变或时慢变的场景。不同数字通道在同一个符号上发送导频序列，通过频分的方式区分开，即K个导频序列中的任意两个导频序列的非零导频对应的子载波不同，每个数字通道采用图24类似的单数字通道的设计。
图25为本申请实施例的一个具体的例子，其中，κ＝2，ι＝0，
Figure PCTCN2017078618-appb-000135
K＝2，NL和NR均为84。两个数字通道采用相同的符号分别发送导频。可以发现，非零导频与ICI扩展及MTI扩展被减弱，非零导频将不受ICI和MTI的影响，并且非零导频间距IFDICI,MTI小于有效信道相干带宽。对于第一个数字通道，直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000136
和
Figure PCTCN2017078618-appb-000137
对于第二个数字通道，直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000138
和
Figure PCTCN2017078618-appb-000139
第三组设计方案的另一种场景为系统具有K个数字通道，其中，K大于或等于2，所述根据所述非零导频最小抗干扰距离，生成导频序列，可以包括：如果所述第二非零导频最小抗干扰距离IFDICI,MTI的K倍大于所述等效信道相干带宽，且所述第二非零导频最小抗干扰距离IFDICI,MTI小于或等于所述等效信道相干带宽，在W个符号上生成K个导频序列，其中，W小于或等于K，第w个符号上生成Kw个导频序列，w的取值为1,2,...,W，Kw小于或等于K”0，K”0为对等效信道相干带宽/IFDICI,MTI下取整，所述第w个符号上的Kw个导频序列中的每个导频序列中任意两个相邻的非零导频的导频间隔小于或等于所述等效信道相干带宽，且大于或等于所述第二非零导频最小抗干扰距离，所述第w个符号上的Kw个导频序列中的任意两个导频序列的非零导频对应的子载波不同。
本申请实施例针对具有K个数字通道的系统，归一化等效信道相干带宽
Figure PCTCN2017078618-appb-000140
ICI系数和MTI系数为时不变或时慢变的场景，在W个符号上生成K个导频序列。首先确定每个符号上可以承载的数字通道的导频的最大值K”0，K”0为对等效信道相干带宽/IFDICI,MTI下取整，即
Figure PCTCN2017078618-appb-000141
定义正整数集{Kw}，其中，Kw≤K0，且K1+K2+...+KW＝K。本申请实施例需要N个符号发送导频序列，符号n(Sym n)承载Kn个数字通道的导频序列。每个符号上导频序列的设计与图25的例子的设计相类似。
从节省开销的角度，W越小越好。优选地，W在满足条件下取最小值。例如，如果K”0＝2，K＝5。优选的设计是K1＝2，K2＝2,K3＝1,W＝3。
图26为本申请实施例的一个具体的例子，其中，κ＝2，ι＝0，K”0＝1，K＝2，K1＝K2＝1，W＝2，NL和NR均为84。第一个数字通道在第一个符号(符号1)上发送，直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000142
和
Figure PCTCN2017078618-appb-000143
第二个数字通道在第二个符号上发送(符号2)，直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000144
和
Figure PCTCN2017078618-appb-000145
第三组设计方案的另一种场景为系统具有K个数字通道，其中，K大于或等于2，所述根据所述非零导频最小抗干扰距离，生成导频序列，可以包括：如果所述第二非零导频最小抗干扰距离IFDICI,MTI大于所述等效信道相干带宽，且所述第一非零导频最小抗干扰距离IFDmain小于或等于所述等效信道相干带宽，在K个A类符号上分别生成K个A类导频序列，在K个B类符号上分别生成K个B类导频序列，其中，所述A类导频序列中的任意两个相邻的非零导频的导频间隔小于或等于所述等效信道相干带宽，且大于或等于所述第一非零导频最小抗干扰距离，所述B类导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述第二非零导频最小抗干扰距离。
本申请实施例针对具有K个数字通道的系统，归一化等效信道相干带宽
Figure PCTCN2017078618-appb-000146
ICI系数和MTI系数为时不变或时慢变的场景。
本申请实施例总共使用2K个导频符号发送导频序列，例如奇数号符号为A类符号，偶数号符号为B类符号。其中，对于数字通道k，在第2k-1个符号采用类似于图14的设计，在第2k个符号采用类似于图23的设计。第2k-1个符号的导频序列用于估计等效信道增益，第2k-1个符号加第2k个符号的导频序列用于估计ICI系数和MTI系数。
图27为本申请实施例的一个具体的例子，其中，κ＝2，ι＝0，K＝2，NL和NR 均为84。本例子共采用4个符号，其中前两个符号用于数字通道1，后两个符号用于数字通道2。符号1和符号3采用类似于图14的设计，并满足D＝IFDmain；符号2和符号4采用类似于图23的设计，并满足D＝IFDICI,MTI。对于数字通道1，在符号1上直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000147
和
Figure PCTCN2017078618-appb-000148
在符号2上直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000149
和
Figure PCTCN2017078618-appb-000150
对于数字通道2，在符号3上直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000151
和在符号4上直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000153
和
Figure PCTCN2017078618-appb-000154
第三组设计方案的另一种场景为系统具有K个数字通道，其中，K大于或等于2，所述根据所述非零导频最小抗干扰距离，生成导频序列，可以包括：如果所述第一非零导频最小抗干扰距离IFDmain大于所述等效信道相干带宽，对于K个数字通道的每个数字通道，在X个连续的A类符号上生成X个A类导频序列，其中，X为对IFDmain/等效信道相干带宽上取整，在X个连续的A类符号后的一个B类符号上生成一个B类导频序列，每个数字通道的所述X个A类导频序列中的任意两个A类导频序列的非零导频对应的子载波不同，所述A类导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述第一非零导频最小抗干扰距离，所述B类导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述第二非零导频最小抗干扰距离。
本申请实施例针对具有K个数字通道的系统，归一化等效信道相干带宽
Figure PCTCN2017078618-appb-000155
ICI系数和MTI系数为时不变或时慢变的场景。本申请实施例共使用(X+1)K个导频符号，其中，为对IFDmain/等效信道相干带宽上取整，即
Figure PCTCN2017078618-appb-000156
对每个数字通道采用X+1个符号，其中前X个连续的符号(A类符号)采用类似于图14的设计，第X+1个符号采用类似于图23的设计。前X个连续的符号的导频序列用于估计等效信道增益，X+1个符号的导频序列用于估计ICI系数和MTI系数。
每一个数字通道的X+1个符号有两种配置方式。第一种，每一个数字通道的X+1个符号连续分配，因此，第k个数字通道分配的符号索引可表示为(k-1)(M+1)+1:k(M+1)。第二种，每一个数字通道的前X个(类似于图14的设计)连续的符号一个接一个放置，K个数字通道全部放置完后，再一个接一个的放置每 个数字通道的第X+1个(类似于图23的设计)符号,因此，第k个数字通道分配的符号索引可表示为(k-1)M+1:kM和KM+k。
图28为本申请实施例的一个具体的例子，其中，κ＝2，ι＝0，
Figure PCTCN2017078618-appb-000157
K＝2，X＝2，NL和NR均为84，共需要6个符号。符号1、符号2、符号4和符号5采用类似于图14的设计，并满足D＝IFDmain；符号3和符号6采用类似于图23的设计，并满足D＝IFDICI,MTI。对于数字通道1，在符号1上直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000158
和
Figure PCTCN2017078618-appb-000159
在符号2上直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000160
和
Figure PCTCN2017078618-appb-000161
在符号3上直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000162
和
Figure PCTCN2017078618-appb-000163
对于数字通道2，在符号4上直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000164
和
Figure PCTCN2017078618-appb-000165
在符号5上直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000166
和
Figure PCTCN2017078618-appb-000167
在符号6上直流子载波左侧和右侧的非零导频的集合分别为
Figure PCTCN2017078618-appb-000168
和
Figure PCTCN2017078618-appb-000169
应理解，在本申请的部分实施例中，ι＝0，其是指系统中存在MTI，MTI的扩展长度为0，即MTI只在非零导频的子载波的镜像位置处存在，亦即只考虑对MTI非零导频的子载波的镜像位置的一个子载波的干扰。
还应理解，在本申请的部分实施例中，任意两个导频序列的非零导频对应的子载波不同是指任意两个导频序列的非零导频的索引index不重叠。
下面通过与现有的导频序列设计方案对比系统的误比特率(Bit Error Ratio，BER)性能来说明本申请实施例可以达到的效果。考虑下行OFDM系统，系统框图如图29所示。下行OFDM系统包括64发送天线，4个接收天线；信道采用第三代合作伙伴计划(3rd Generation Partnership Project，3GPP)的空间信道模型(Spatial Channel Model，SCM)，2簇20径，第二个簇相对第一簇的时延为80ns，功率降低9dB；模拟端波束成形(beamforming)码本第一簇的主方向；单个数字通道；调制模式为16QAm；OFDM的DFT点数为256，子载波间隔为1.44MHz，信号带宽为250MHz，其中168个子载波为有效子载波；收、发端相噪的独立用分布，其功率谱密度满足模型
Figure PCTCN2017078618-appb-000170
其中PSD(0)＝-60dBc/Hz，PSD(100k)＝-70dBc/Hz；收、发端频偏独立同分布，大小为±1ppm；收、发端IQ不平衡独立同分布，满足最大幅度不平衡为4dB，最大相位不平衡为5°；非线性功率失真参照IEEE 802.11ad，大小为9dB；移动速度为10km/h，系统信噪比(Signal Noise Ratio)SNR＝10dB；一个发送帧大小为7个OFDM符号。
系统非编码条件下的BER曲线如图30所示。可以看出，在强RFD条件下，现有的方案系统受到了严重的影响，性能较差；本申请实施例的导频序列的设计方案，充分考虑了各个强RFD的相互影响，可以更有效的对抗强RFD，可以保证通信的可靠性。同时，本方案也可以降低设备的开销。
针对接收端，本申请实施例还提供了一种传输导频信号的方法，可以包括：接收导频序列，所述导频序列中任意两个相邻的非零导频的导频间隔是根据射频失真条件下干扰的扩展长度确定的，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，所述非零导频的子载波对应的镜像子载波为空子载波；根据所述导频序列估计等效信道增益或估计射频失真条件下的至少两种干扰。
从结果上来看，该方法可以包括：接收导频序列，所述导频序列中任意两个相邻的非零导频的导频间隔大于或等于1，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，所述非零导频的子载波对应的镜像子载波为空子载波；根据所述导频序列估计等效信道增益或估计射频失真条件下的至少两种干扰。
可选地，作为一个实施例，所述非零导频的子载波对应的镜像子载波左右分别相邻的子载波也为空子载波。
可选地，作为一个实施例，所述导频序列用于估计等效信道增益，是根据系统的等效信道相干带宽生成的，所述导频间隔使得干扰对非零导频的干扰影响第一阈值。
可选地，作为一个实施例，所述导频序列用于估计射频失真条件下的至少两种干扰，所述导频间隔使得所述至少两种干扰对非零导频的影响小于第一阈值，并且所述导频间隔使得所述至少两种干扰相互之间的影响小于第二阈值。
其中，所述方法可以还包括：在接收所述导频序列的符号上，还接收数据信号。
可选地，作为一个实施例，所述接收导频序列，包括：在第一类符号上接收第一类导频序列，所述第一类导频序列中任意两个相邻的非零导频的第一导频间隔使得干扰对非零导频的影响小于第一阈值；在第二类符号上接收第二类导频序列，所述第二类导频序列中任意两个相邻的非零导频的第二导频间隔使得干扰对非零导频的影响小于第一阈值，并且所述第二导频间隔使得所述至少两种干扰相互之间的影响小于第二阈值；所述根据所述导频序列估计等效信道增益或估计射频失真条件下的至少两种干扰，包括：根据所述第一类导频序列估计等效信道增益。根据所述第二类导频序列估计射频失真条件下的至少两种干扰。
可选地，作为一个实施例，所述导频序列由多个基本导频单元级联生成，所述基本导频单元中包括一个非零导频。
可选地，作为一个实施例，所述扩展长度包括载波间干扰ICI扩展长度和镜像干扰 MTI扩展长度，所述少两种干扰包括ICI和MTI。
可选地，作为一个实施例，所述所述导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述非零导频最小抗干扰距离，所述非零导频最小抗干扰距离是根据所述射频失真条件下干扰的扩展长度确定的。
上文中结合图7至图30，详细描述了根据本申请实施例的传输导频信号的方法，下面将结合图31至图32，详细描述根据本申请实施例的传输导频信号的设备。
图31示出了根据本申请实施例的传输导频信号的设备2600的示意性框图。如图31所示，该设备2600包括：
处理模块2610，用于确定导频序列中任意两个相邻的非零导频的导频间隔，所述导频间隔是根据射频失真条件下干扰的扩展长度确定的；
所述处理模块2610还用于根据所述导频间隔生成所述导频序列，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，所述导频序列的非零导频的子载波对应的镜像子载波为空子载波；
发送模块2620，用于发送所述处理模块2610生成的所述导频序列。
因此，在本申请实施例的设备，为导频序列分配非零导频载波的同时，还为其分配零导频载波，非零导频的导频间隔设计基于不被不干扰的原则，使非零导频载波和数据受到干扰的影响明显减弱，从而使得系统受射频失真的影响较小，提升系统的性能。
可选地，作为一个实施例，所述非零导频的子载波对应的镜像子载波左右分别相邻的子载波也为空子载波。
可选地，作为一个实施例，所述导频序列用于估计等效信道增益，所述导频间隔使得干扰对非零导频的影响小于第一阈值，所述处理模块2610根据所述导频间隔生成所述导频序列，包括：
根据所述导频间隔和系统的等效信道相干带宽，生成所述导频序列。
可选地，作为一个实施例，所述导频序列用于估计射频失真条件下的至少两种干扰，所述导频间隔使得所述至少两种干扰对非零导频的影响小于第一阈值，并且所述导频间隔使得所述至少两种干扰相互之间的影响小于第二阈值。
可选地，作为一个实施例，所述发送模块2620具体用于在相应的符号上发送所述导频序列；所述发送模块2620还用于：在所述符号上还发送数据信号。
可选地，作为一个实施例，所述导频序列包括第一类导频序列和第二类导频序列，所述第一类导频序列用于估计等效信道增益，所述第一类导频序列中任意两个相邻的非零导频的导频间隔为第一导频间隔，所述第二类导频序列用于估计射频失真条件下的至少两种干扰，所述第二类导频序列中任意两个相邻的非零导频的导频间隔为第二导频间隔，所述处理模块2610根据所述导频间隔生成所述导频序列，包括：
生成所述第一类导频序列，所述第一类导频序列根据所述第一导频间隔和系统的等效信道相干带宽生成，所述第一导频间隔使得干扰对非零导频的影响小于第一阈值；
生成所述第二类导频序列，所述第二类导频序列根据所述第二导频间隔生成，所述第二类导频序列中任意两个相邻的非零导频的第二导频间隔使得干扰对非零导频的影响小于第一阈值，并且所述第二导频间隔使得所述至少两种干扰相互之间的影响小于第二阈值；
所述发送模块2620具体用于：
在第一类符号上发送所述第一类导频序列；
在第二类符号上发送所述第二类导频序列。
可选地，作为一个实施例，其特征在于，所述导频序列由多个基本导频单元级联生成，所述基本导频单元中包括一个非零导频。
可选地，作为一个实施例，所述扩展长度包括载波间干扰ICI扩展长度和镜像干扰MTI扩展长度。
可选地，作为一个实施例，所述处理模块2610确定导频序列中任意两个相邻的非零导频的导频间隔，包括：
根据所述射频失真条件下干扰的扩展长度，确定非零导频最小抗干扰距离；
根据所述非零导频最小抗干扰距离，确定所述导频间隔，所述导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述非零导频最小抗干扰距离。
应注意，本申请实施例中，处理模块2610可以由处理器实现，发送模块2620可以由收发器实现。如图31所示，传输导频信号的设备2700可以包括处理器2710、收发器2720和存储器2730。其中，存储器2730可以用于存储处理器2710执行的代码等。
设备2700中的各个组件通过总线系统2740耦合在一起，其中总线系统2740除包括数据总线之外，还包括电源总线、控制总线和状态信号总线。
图31所示的设备2600或图32所示的接收端2700能够实现前述图7至图30的实施例中所实现的各个过程，为避免重复，这里不再赘述。
应理解，在本申请实施例中，该处理器2710可以是中央处理单元(Central Processing Unit，简称为“CPU”)，该处理器2710还可以是其他通用处理器、数字信号处理器(DSP)、专用集成电路(ASIC)、现成可编程门阵列(FPGA)或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件等。通用处理器可以是微处理器或者该处理器也可以是任何常规的处理器等。
该存储器2720可以包括只读存储器和随机存取存储器，并向处理器2710提供指令和数据。存储器2720的一部分还可以包括非易失性随机存取存储器。例如，存储器2720还可以存储设备类型的信息。
该总线系统2730除包括数据总线之外，还可以包括电源总线、控制总线和状态信号总线等。但是为了清楚说明起见，在图中将各种总线都标为总线系统2730。
在实现过程中，上述方法的各步骤可以通过处理器2710中的硬件的集成逻辑电路或者软件形式的指令完成。结合本申请实施例所公开的方法的步骤可以直接体现为硬件处理器执行完成，或者用处理器中的硬件及软件模块组合执行完成。软件模块可以位于随机存储器，闪存、只读存储器，可编程只读存储器或者电可擦写可编程存储器、寄存器等本领域成熟的存储介质中。该存储介质位于存储器2720，处理器2710读取存储器2720中的信息，结合其硬件完成上述方法的步骤。为避免重复，这里不再详细描述。
本申请实施例还提供了一种传输导频信号的设备(接收端)。该设备包括：
接收模块，用于接收导频序列，所述导频序列中任意两个相邻的非零导频的导频间隔是根据射频失真条件下干扰的扩展长度确定的，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，所述非零导频的子载波对应的镜像子载波为空子载波；
处理模块，用于根据所述接收模块接收的所述导频序列估计等效信道增益或估计射频失真条件下的至少两种干扰。
换而言之，接收模块可以用于接收导频序列，所述导频序列中任意两个相邻的非零导频的导频间隔大于或等于1，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，所述非零导频的子载波对应的镜像子载波为空子载波；处理模块可以用于根据所述接收模块接收的所述导频序列估计等效信道增益或估计射频失真条件下的至少两种干扰。
在本申请实施例中，为系统分配非零导频载波的同时，还为系统分配零导频载波，非零导频的导频间隔设计基于不被不干扰的原则，使非零导频载波和数据受到干扰的影响明显减弱，从而使得系统受射频失真的影响较小，能够更准确的估计等效信道增益或估计射频失真条件下的至少两种干扰，提升系统的性能。
可选地，作为一个实施例，所述非零导频的子载波对应的镜像子载波左右分别相邻的子载波也为空子载波。
可选地，作为一个实施例，所述导频序列用于估计等效信道增益，是根据系统的等效信道相干带宽生成的，所述导频间隔使得干扰对非零导频的影响小于第一阈值。
可选地，作为一个实施例，所述导频序列用于估计射频失真条件下的至少两种干扰，所述导频间隔使得所述至少两种干扰对非零导频的影响小于第一阈值，并且所述导频间隔使得所述至少两种干扰相互之间的影响小于第二阈值。
其中，所述接收模块还用于在接收所述导频序列的符号上，还接收数据信号。
可选地，作为一个实施例，所述接收模块具体用于在第一类符号上接收第一类导频序列，所述第一类导频序列中任意两个相邻的非零导频的第一导频间隔使得干扰对非零导频的影响小于第一阈值；在第二类符号上接收第二类导频序列，所述第二类导频序列中任意两个相邻的非零导频的第二导频间隔使得干扰对非零导频的影响小于第一阈值，并且所述第二导频间隔使得所述至少两种干扰相互之间的影响小于第二阈值；所述处理模块具体用于：根据所述第一类导频序列估计等效信道增益。根据所述第二类导频序列估计射频失真条件下的至少两种干扰。
可选地，作为一个实施例，所述导频序列由多个基本导频单元级联生成，所述基本导频单元中包括一个非零导频。
可选地，作为一个实施例，所述扩展长度包括载波间干扰ICI扩展长度和镜像干扰MTI扩展长度，所述少两种干扰包括ICI和MTI。
可选地，作为一个实施例，所述所述导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述非零导频最小抗干扰距离，所述非零导频最小抗干扰距离是根据所述射频失真条件下干扰的扩展长度确定的。
应注意，本申请实施例中，接收模块可以由收发器实现，处理模块可以由处理器实现。传输导频信号的设备可以包括处理器、收发器和存储器。其中，存储器可以用于存储处理器执行的代码等。
设备中的各个组件通过总线系统耦合在一起，其中总线系统除包括数据总线之外，还包括电源总线、控制总线和状态信号总线。
发送端的传输导频信号的设备能够实现前述图7至图30的实施例中所实现的各个过程，为避免重复，这里不再赘述。
本申请各个实施例可以应用于终端设备中。终端设备可以经无线接入网(Radio Access Network，RAN)与一个或多个核心网进行通信，终端设备可以指用户设备(User  Equipment，UE)、接入终端、用户单元、用户站、移动站、移动台、远方站、远程终端、移动设备、用户终端、终端、无线通信设备、用户代理或用户装置。接入终端可以是蜂窝电话、无绳电话、会话启动协议(Session Initiation Protocol，SIP)电话、无线本地环路(Wireless Local Loop，WLL)站、个人数字处理(Personal Digital Assistant，PDA)、具有无线通信功能的手持设备、计算设备或连接到无线调制解调器的其它处理设备、车载设备、可穿戴设备，未来5G网络中的终端设备等。
本申请各个实施例也可以应用于网络设备中。网络设备可以是用于与终端设备进行通信的设备，例如，可以是GSM系统或CDMA中的基站(Base Transceiver Station，BTS)，也可以是WCDMA系统中的基站(NodeB，NB)，还可以是LTE系统中的演进型基站(Evolutional Node B，eNB或eNodeB)，或者该网络设备可以为中继站、接入点、车载设备、可穿戴设备以及未来5G网络中的网络侧设备或未来演进的PLMN网络中的网络设备等。
此外，本申请的各个方面或特征可以实现成方法、装置或使用标准编程和/或工程技术的制品。本申请中使用的术语“制品”涵盖可从任何计算机可读器件、载体或介质访问的计算机程序。例如，计算机可读介质可以包括，但不限于:磁存储器件(例如，硬盘、软盘或磁带等)，光盘(例如，压缩盘(Compact Disk，CD)、数字通用盘(Digital Versatile Disk，DVD)等)，智能卡和闪存器件(例如，可擦写可编程只读存储器(Erasable Programmable Read-Only Memory，EPROM)、卡、棒或钥匙驱动器等)。另外，本文描述的各种存储介质可代表用于存储信息的一个或多个设备和/或其它机器可读介质。术语“机器可读介质”可包括但不限于，无线信道和能够存储、包含和/或承载指令和/或数据的各种其它介质。
应理解，本文中涉及的第一、第二、第三、第四以及各种数字编号仅为描述方便进行的区分，并不用来限制本申请实施例的范围。
应理解，本文中术语“和/或”，仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本文中字符“/”，一般表示前后关联对象是一种“或”的关系。
应理解，在本申请的各种实施例中，上述各过程的序号的大小并不意味着执行顺序的先后，各过程的执行顺序应以其功能和内在逻辑确定，而不应对本申请实施例的实施过程构成任何限定。
本领域普通技术人员可以意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，能够以电子硬件、或者计算机软件和电子硬件的结合来实现。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，上述描述的系统、装置和单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。
在本申请所提供的几个实施例中，应该理解到，所揭露的系统、装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，所述单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。另一 点，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或单元的间接耦合或通信连接，可以是电性，机械或其它的形式。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外，在本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。
所述功能如果以软件功能单元的形式实现并作为独立的产品销售或使用时，可以存储在一个计算机可读取存储介质中。基于这样的理解，本申请的技术方案本质上或者说对现有技术做出贡献的部分或者该技术方案的部分可以以软件产品的形式体现出来，该计算机软件产品存储在一个存储介质中，包括若干指令用以使得一台计算机设备(可以是个人计算机，服务器，或者网络设备等)执行本申请各个实施例所述方法的全部或部分步骤。而前述的存储介质包括：U盘、移动硬盘、只读存储器(Read-Only Memory，ROM)、随机存取存储器(Random Access Memory，RAM)、磁碟或者光盘等各种可以存储程序代码的介质。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (18)

  1. 一种传输导频信号的方法，其特征在于，包括：
    确定导频序列中任意两个相邻的非零导频的导频间隔，所述导频间隔是根据射频失真条件下干扰的扩展长度确定的；
    根据所述导频间隔生成所述导频序列，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，所述导频序列的非零导频的子载波对应的镜像子载波为空子载波；
    发送所述导频序列。
  2. 根据权利要求1所述的方法，其特征在于，所述非零导频的子载波对应的镜像子载波左右分别相邻的子载波为空子载波。
  3. 根据权利要求1或2所述的方法，其特征在于，所述导频序列用于估计等效信道增益，所述导频间隔使得干扰对所述非零导频的影响小于第一阈值，所述根据所述导频间隔生成所述导频序列，包括：
    根据所述导频间隔和系统的等效信道相干带宽，生成所述导频序列。
  4. 根据权利要求1或2所述的方法，其特征在于，所述导频序列用于估计射频失真条件下的至少两种干扰，所述导频间隔使得所述至少两种干扰对非零导频的影响小于第一阈值，并且所述导频间隔使得所述至少两种干扰相互之间的影响小于第二阈值。
  5. 根据权利要求4所述的方法，其特征在于，所述发送所述导频序列，包括：
    在相应的符号上发送所述导频序列；
    所述方法还包括：
    在所述符号上还发送数据信号。
  6. 根据权利要求1或2所述的方法，其特征在于，所述导频序列包括第一类导频序列和第二类导频序列，所述第一类导频序列用于估计等效信道增益，所述第一类导频序列中任意两个相邻的非零导频的导频间隔为第一导频间隔，所述第二类导频序列用于估计射频失真条件下的至少两种干扰，所述第二类导频序列中任意两个相邻的非零导频的导频间隔为第二导频间隔，所述根据所述导频间隔生成所述导频序列，包括：
    生成所述第一类导频序列，所述第一类导频序列根据所述第一导频间隔和系统的等效信道相干带宽生成，所述第一导频间隔使得干扰对非零导频的影响小于第一阈值；
    生成所述第二类导频序列，所述第二类导频序列根据所述第二导频间隔生成，所述第二类导频序列中任意两个相邻的非零导频的第二导频间隔使得干扰对非零导频的影响小于第一阈值，并且所述第二导频间隔使得所述至少两种干扰相互之间的影响小于第二阈值；
    所述发送所述导频序列，包括：
    在第一类符号上发送所述第一类导频序列；
    在第二类符号上发送所述第二类导频序列。
  7. 根据权利要求1至6中任一项所述的方法，其特征在于，所述导频序列由多个基本导频单元级联生成，所述基本导频单元中包括一个非零导频。
  8. 根据权利要求1至7中任一项所述的方法，其特征在于，所述扩展长度包括载波间干扰ICI扩展长度和镜像干扰MTI扩展长度。
  9. 根据权利要求1至8中任一项所述的方法，其特征在于，所述确定导频序列中任意两个相邻的非零导频的导频间隔，包括：
    根据所述射频失真条件下干扰的扩展长度，确定非零导频最小抗干扰距离；
    根据所述非零导频最小抗干扰距离，确定所述导频间隔，所述导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述非零导频最小抗干扰距离。
  10. 一种传输导频信号的设备，其特征在于，包括：
    处理模块，用于确定导频序列中任意两个相邻的非零导频的导频间隔，所述导频间隔是根据射频失真条件下干扰的扩展长度确定的；
    所述处理模块还用于根据所述导频间隔生成所述导频序列，所述导频序列中任意两个相邻的非零导频之间的导频为零导频，所述导频序列的非零导频的子载波对应的镜像子载波为空子载波；
    发送模块，用于发送所述处理模块生成的所述导频序列。
  11. 根据权利要求10所述的设备，其特征在于，所述非零导频的子载波对应的镜像子载波左右分别相邻的子载波为空子载波。
  12. 根据权利要求10或11所述的设备，其特征在于，所述导频序列用于估计等效信道增益，所述导频间隔使得干扰对非零导频的影响小于第一阈值，所述处理模块根据所述导频间隔生成所述导频序列，包括：
    根据所述导频间隔和系统的等效信道相干带宽，生成所述导频序列。
  13. 根据权利要求10或11所述的设备，其特征在于，所述导频序列用于估计射频失真条件下的至少两种干扰，所述导频间隔使得所述至少两种干扰对非零导频的影响小于第一阈值，并且所述导频间隔使得所述至少两种干扰相互之间的影响小于第二阈值。
  14. 根据权利要求13所述的设备，其特征在于，所述发送模块具体用于在相应的符号上发送所述导频序列；
    所述发送模块还用于：
    在所述符号上还发送数据信号。
  15. 根据权利要求10或11所述的设备，其特征在于，所述导频序列包括第一类导频序列和第二类导频序列，所述第一类导频序列用于估计等效信道增益，所述第一类导频序列中任意两个相邻的非零导频的导频间隔为第一导频间隔，所述第二类导频序列用于估计射频失真条件下的至少两种干扰，所述第二类导频序列中任意两个相邻的非零导频的导频间隔为第二导频间隔，所述处理模块根据所述导频间隔生成所述导频序列，包括：
    生成所述第一类导频序列，所述第一类导频序列根据所述第一导频间隔和系统的等效信道相干带宽生成，所述第一导频间隔使得干扰对非零导频的影响小于第一阈值；
    生成所述第二类导频序列，所述第二类导频序列根据所述第二导频间隔生成，所述第二类导频序列中任意两个相邻的非零导频的第二导频间隔使得干扰对非零导频的影响小于第一阈值，并且所述第二导频间隔使得所述至少两种干扰相互之间的影响小于第二阈值；
    所述发送模块具体用于：
    在第一类符号上发送所述第一类导频序列；
    在第二类符号上发送所述第二类导频序列。
  16. 根据权利要求10至15中任一项所述的设备，其特征在于，所述导频序列由多个基本导频单元级联生成，所述基本导频单元中包括一个非零导频。
  17. 根据权利要求10至16中任一项所述的设备，其特征在于，所述扩展长度包括载波间干扰ICI扩展长度和镜像干扰MTI扩展长度。
  18. 根据权利要求10至17中任一项所述的设备，其特征在于，所述处理模块确定导频序列中任意两个相邻的非零导频的导频间隔，包括：
    根据所述射频失真条件下干扰的扩展长度，确定非零导频最小抗干扰距离；
    根据所述非零导频最小抗干扰距离，确定所述导频间隔，所述导频序列中的任意两个相邻的非零导频的导频间隔大于或等于所述非零导频最小抗干扰距离。
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