WO2005122447A1 - Procede de mise en oeuvre d'une estimation de voie dans un systeme ofdm - Google Patents

Procede de mise en oeuvre d'une estimation de voie dans un systeme ofdm Download PDF

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Publication number
WO2005122447A1
WO2005122447A1 PCT/CN2005/000756 CN2005000756W WO2005122447A1 WO 2005122447 A1 WO2005122447 A1 WO 2005122447A1 CN 2005000756 W CN2005000756 W CN 2005000756W WO 2005122447 A1 WO2005122447 A1 WO 2005122447A1
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Prior art keywords
domain channel
time
ofdm symbol
pilot
frequency
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PCT/CN2005/000756
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English (en)
Chinese (zh)
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Shujun Dang
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Huawei Technologies Co., Ltd.
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Publication of WO2005122447A1 publication Critical patent/WO2005122447A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/022—Channel estimation of frequency response
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/0202—Channel estimation
    • H04L25/0224—Channel estimation using sounding signals
    • H04L25/0228—Channel estimation using sounding signals with direct estimation from sounding signals
    • 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
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only

Definitions

  • the present invention relates to Orthogonal Multiplexing Frequency Division Multiplexing (OFDM) technology, and more particularly to a method for implementing channel estimation in an OFDM system.
  • OFDM Orthogonal Multiplexing Frequency Division Multiplexing
  • OFDM technology As a frequency division multiplexing technology capable of transmitting high-rate data services, OFDM technology, compared with traditional single-carrier technology, can use a simple equalization algorithm to provide extremely high spectral efficiency. On the other hand, In a system using OFDM, there is no need to allocate a wider protection bandwidth between adjacent carriers as in traditional frequency division multiplexing (FDM), and mutual interference between subcarriers can be avoided, thereby saving bandwidth.
  • FDM frequency division multiplexing
  • OFDM OFDM 'technology has been widely used in existing communication systems, and this technology has been reflected in the wireless local area network standard 802.11a and fixed wireless access standard 802.16a.
  • the radio access network of the 3rd Generation Partnership Project (3GPP) and the physical layer of IEEE 802.20 are also considering the use of OFDM technology to build mobile radios with higher frequency efficiency. Communication access system.
  • FIG 1 shows the networking diagram of a typical frequency cellular multiplexing system.
  • two radio network controllers namely RNC1 and RNC2
  • RNC1 and RNC2 are connected to the core network (CN)
  • BS base stations
  • BS1 and BS3 are connected to RNC1 and BS4
  • BS5 and BS6 are connected to RNC2
  • MS mobile stations
  • Figure 2 shows a typical cell omnidirectional antenna multiplexing method, referred to as a cell multiplexing method for short
  • Figure 3 shows a typical cell 120-degree directional antenna multiplexing method, which is called a sector multiplexing method.
  • the data transmission system using OFDM technology has the following advantages:
  • an OFDM The symbol time domain includes two parts: a data part and a cyclic prefix part.
  • the shield ring prefix part is cyclically generated from the end of the data part.
  • the time taken by the data part in the figure is'.
  • the time taken by the cyclic prefix part is.
  • the fault tolerance of OFDM technology is as follows: Compared with the duration Ts of an OFDM symbol, the duration of a typical channel impulse response is very small, occupying only a small part of Ts. Therefore, by adding a smaller cyclic prefix, That is, to completely overcome the interference between signals caused by multipath.
  • OFDM technology can recover digital signals carried by strong fading subcarriers by adopting redundant schemes such as channel coding.
  • the OFDM technology has higher spectrum efficiency.
  • the purpose of the channel estimation in the above key technology is: The receiver obtains the frequency domain channel information of the data transmitted by the transmitter through the channel estimation. After obtaining the frequency domain channel information, the receiver can perform processing such as equalization according to the frequency domain channel information to obtain corresponding data. Therefore, the channel estimation technology is an important prerequisite for the receiver to correctly acquire the data.
  • the IEEE 802.11a protocol provides channel estimation techniques. Specifically, the frame structure in the 802.11a system is shown in FIG. 5, and the beginning of each frame includes a preamble, and thereafter It is an indefinite-length data OFDM symbol. The data OFDM symbol includes user data and signaling.
  • the pilot allocation scheme for 802.1la is shown in Figure 6.
  • Preamble is used for channel estimation. Specifically, since the receiver knows the data carried by each subcarrier of the preamble transmitted by the transmitter, the channel conditions experienced by each subcarrier of the preamble can be obtained by using the received preamble, and the channel environment changes slowly. In the case of a channel, the channel conditions experienced by each subcarrier of the Preamble can be regarded as the channel conditions experienced by the subcarrier corresponding to the data OFDM symbol corresponding to the Preamble.
  • the solution provided by the 802.11 protocol is to approximate the channel conditions of the data OFDM symbols to the channel conditions of the corresponding Preamble.
  • this solution if the channel environment in the system changes rapidly, this approximation will bring large errors.
  • the relative movement between the receiver and the transmitter will cause the channel environment to change, so This solution will have certain limitations when applied to systems where the channel environment changes rapidly.
  • the current channel changes of mobile wireless communication systems tend to be fast. Obviously, the above scheme is not suitable for use in mobile wireless communication systems.
  • the OFDM implementation of 802.11a introduces pilot subcarriers to track channel changes to modify the channel conditions experienced by each subcarrier of the Preamble, and uses the modified channel conditions as corresponding data OFDM symbols Channel value of the subcarrier, but this correction cannot fully reflect the rapid change of the channel and still cause a large performance loss.
  • pilot frequency allocation mode in a time-frequency grid mode.
  • This allocation mode is shown in FIG. 7.
  • the pilot OFDM symbols in this method, namely Preamble, are evenly distributed on the time-frequency plane. Therefore, tracking the channel changes with the pilot OFDM symbols can solve the problem of channel environment changes to a certain extent.
  • Siemens has submitted a proposal to 3GPP RAN1 Tdoc R1-030780
  • a specific time-frequency grid point pilot allocation mode a corresponding channel estimation method, and corresponding simulation results are proposed.
  • This method specifically uses two 7-male interpolation methods.
  • three Lagrangian interpolations are performed in the time domain, and then seven Lagrangian interpolations are performed in the frequency domain to obtain data transmitted on the time-frequency plane.
  • Channel conditions for subcarriers Channel conditions for subcarriers.
  • the simulation results provided by Siemens show that: relative to the ideal channel estimation, Siemens' channel estimation scheme has a performance loss of 0.5-0.7dB for PA3, PB3> VA30 channels, and for VB30 channels, even a floor appears at BLER-0.13. Therefore, if the channel is a large delay channel, the Siemens channel estimation method will show a large performance loss. Summary of the invention
  • the main object of the present invention is to provide a method for implementing channel estimation in an orthogonal multiple channel frequency division multiplexing system, so as to reduce the performance loss of the receiver when performing channel estimation.
  • a method for implementing channel estimation in an orthogonal multiple channel frequency division multiplexing system includes the following steps:
  • the receiving end obtains the frequency domain received signal received on the subcarrier where the pilot is located according to the received time domain received signal;
  • the step b includes the following steps:
  • the step C includes the following steps:
  • time-domain channel information at an OFDM symbol adjacent to the OFDM symbol containing the pilot sub-carrier and containing data is obtained;
  • the step c includes the following steps:
  • the receiving end obtains the frequency domain received signal received by the subcarrier where the pilot is located according to the received time domain received signal, and then obtains the frequency domain received signal based on the frequency domain received signal received on the pilot subcarrier located on the same OFDM symbol.
  • the time-domain channel information at the pilot subcarrier corresponding to the OFDM symbol, and then the frequency-domain channel information at the sub-carrier where the data symbol is located is estimated based on the time-domain channel information, so that the channel environment changes rapidly and the delay is high. Can achieve better performance.
  • the solution of the invention strengthens the applicability of the data communication system to the channel environment, improves the performance of the actual channel estimation in the OFDM system, and thereby improves the data transmission efficiency of the actual system.
  • Figure 1 is a networking diagram of a typical frequency cellular multiplexing system
  • FIG. 2 is a schematic diagram of a typical cell omnidirectional antenna multiplexing method
  • 3 is a schematic diagram of a typical 120-degree directional antenna multiplexing mode in a cell; 4 is a schematic diagram of an OFDM symbol;
  • FIG. 5 is a schematic diagram of a frame structure provided by 802.11a;
  • FIG. 6 is a schematic diagram of a pilot allocation scheme of 802.11a
  • FIG. 7 is a schematic diagram of a pilot grid mode
  • FIG. 8 is a schematic flow chart of transmitting an OFDM symbol at a transmitting end
  • FIG. 9 is a schematic flowchart of a receiver receiving an OFDM symbol
  • FIG. 11 is a schematic structural diagram of a pilot OFDM symbol
  • FIG. 12 is a schematic structural diagram of a data OFDM symbol
  • FIG. 13 is a schematic diagram of a numbered segment of an OFDM symbol in a solution of the present invention.
  • FIG. 14 is a schematic diagram of a process of performing channel estimation by a receiving end according to an embodiment of the present invention.
  • FIG. 15 is a flowchart of a first processing manner in a solution of the present invention.
  • 16 is a schematic diagram of a pilot allocation pattern of a pilot grid point
  • FIG. 17 is a flowchart of processing based on a pilot grid in a first processing mode of the present invention
  • FIG. 18 is a flowchart of a second processing mode in a solution of the present invention
  • FIG. 19 is a schematic diagram showing the distribution of irregular pilot OFDM symbols and data OFDM symbols
  • FIG. 20 is a flowchart of a third processing mode in the solution of the present invention.
  • FIG. 21 is a schematic diagram of a channel estimation performance obtained by using the solution of the present invention when the number of truncated paths is 32 and the ehicle A channel is 30 kmph;
  • FIG. 22 is a schematic diagram of a channel estimation performance obtained by using the solution of the present invention when the number of truncated paths is 32, and the vehicle A channel is 60 kmph;
  • FIG. 23 is a schematic diagram of the channel estimation performance obtained by using the solution of the present invention when the number of truncated diameters is 160 and the vehicle B channel is 30 kmph.
  • the receiving end first needs to receive the OFDM symbol transmitted by the transmitting end, and then perform channel estimation on the received OFDM signal. .,
  • the transmitting end first multiplexes the pilot symbol and the t data symbol according to the multiplexing manner of the pilot symbol and the t data symbol on the time-frequency plane to generate a frequency domain signal for transmission. After that, the frequency domain signal is further processed. Perform inverse Fourier transform, digital-to-analog conversion and other processes, and emit the finally generated electromagnetic signal. This process is shown in Figure 8.
  • For the receiving end after receiving the signal transmitted by the transmitting end, first perform data sampling on the electromagnetic signals received from the channel; and then perform OFDM symbols on the received sampling data in the time domain according to the acquired synchronization information. Extraction, Fourier transform, and demultiplexing to form received pilot symbols and data symbols; then use the received pilot symbols and pilot symbols transmitted by the transmitting end at corresponding time-frequency positions to perform channel estimation to obtain a time-frequency plane Frequency-domain channel information at the time-frequency point on the bearer data. This process is shown in Figure 9.
  • the receiver has three processing methods for channel estimation.
  • the first processing method is: The receiver first obtains the corresponding frequency domain received signal according to the time domain received signal on the subcarrier where the received pilot is located; According to the frequency domain signals received on the pilot subcarriers located on the same OFDM symbol, obtain the time domain channel response at the OFDM symbol; and obtain channel information such as path delay and path attenuation from the time domain channel response. ; And then based on the time domain channel information at the OFDM symbol containing the pilot subcarriers and using a specific interpolation algorithm to estimate the time domain channel information at the OFDM symbol containing the data; Time domain channel information to obtain frequency domain channel information at the OFDM symbol, That is, the frequency domain channel information at the subcarrier corresponding to the data.
  • the second processing method also first obtains the time-domain channel information at the OFDM symbol containing the pilot subcarrier according to the time-domain received signal of the received subcarrier of the pilot. After the time domain channel information at the OFDM symbol, the corresponding frequency domain channel information is obtained according to the information, and then the frequency domain channel information is subjected to interpolation processing to obtain the frequency domain channel information at the OFDM symbol containing the data.
  • the third processing method is similar to the second processing method, and firstly obtains the frequency-domain channel information at the OFDM symbol containing the pilot subcarriers.
  • the difference from the second processing method is that the When the frequency domain channel information at the OFDM symbol of the carrier is used to obtain the frequency domain channel information at the OFDM symbol containing the data, the frequency domain channel information at the OFDM symbol containing the pilot subcarrier may be directly adjacent to the OFDM symbol, Frequency domain channel information at OFDM symbols containing data.
  • the OFDM symbols containing pilot subcarriers used for channel estimation are preferably those OFDM symbols with dense pilot subcarriers.
  • the above-mentioned first processing method is similar to the second processing method, except that the first processing method first obtains the OFDM symbols containing data after acquiring time-domain channel information at the OFDM symbols including the pilot subcarriers. The corresponding time domain channel information, and then obtain the corresponding frequency domain channel information according to the time domain channel information; the second processing method, after obtaining the time domain channel information at the OFDM symbol containing the pilot subcarrier, first obtain the corresponding Frequency domain channel information, and then frequency domain channel information at the OFDM symbol containing the data is estimated based on the frequency domain channel information. Therefore, the following describes the first processing method in detail only by using specific embodiments.
  • the distribution of pilot OFDM symbols and data OFDM symbols in the regular time domain using OFDM symbols is a pilot allocation mode. Based on this allocation mode, the receiver uses the first processing method to perform channel estimation.
  • the mode A specific implementation of is shown in FIG. 10, and n data OFDM symbols are included between two adjacent pilot OFDM symbols.
  • the length of the pilot OFDM symbol may be the same as or different from the length of the data OFDM symbol
  • the pilot OFDM symbol and the data OFDM symbol are also composed of a cyclic prefix part and a data part
  • the cyclic prefix part is composed of a data part
  • the end of is generated cyclically, where the length of the cyclic prefix part and the data part is the number of sampling points occupied by the part.
  • the structure of the pilot OFDM symbol is shown in Figure 11, where the length of the cyclic prefix part is ⁇ ⁇ , and the length of the data part is N Arfato ; the structure of the data OFDM symbol is shown in Figure 12, where the length of the cyclic prefix part is The length of the data part is N ⁇ a .
  • pilot OFDM symbols are numbered sequentially in accordance with the time sequence of transmission, where the pilot OFDM symbols transmitted first are numbered smaller;
  • N data of adjacent pilot OFDM symbols Natural numbering of OFDM symbols: sequentially numbered from 1 to n, where the number of the first transmitted data OFDM symbol is smaller;
  • Number of data OFDM symbols The number of pilot OFDM symbols adjacent to itself and transmitted before itself is multiplied by the number of data OFDM symbols between adjacent pilot OFDM symbols, and then the data OFDM symbols are added in Natural numbering between adjacent pilot OFDM symbols.
  • the numbering segment of an OFDM symbol using the above numbering rule is shown in FIG. 13, where k-1, k, k + 1, and k + 2 are the numbers of pilot OFDM symbols; ... N * (k-1) + n is the number of data OFDM symbols between pilot OFDM symbols k-1 and k; n * k + 1 ... n * k + n is the number of pilot OFDM symbols k and k + 1 The number of data OFDM symbols in the interval; n * (k + l) + 1 ... n * (k + 1) + n is the pilot OFDM symbol k The number of data OFDM symbols between +1 and k + 2.
  • Step 1501 the receiving end according to the received The received signal in the time domain acquires the channel response in the time domain at the pilot OFDM symbol.
  • the OFDM symbols include pilot OFDM symbols and data OKDM symbols.
  • the pilot OFDM symbols only include pilot subcarriers
  • the data OFDM symbols only include data.
  • a time-domain channel response at the OFDM symbol is obtained according to a frequency-domain signal received on a pilot sub-carrier located on the same OFDM symbol.
  • the frequency domain signal acquires the time domain channel response at the pilot OFDM symbol.
  • the receiving end in this step first needs to obtain the frequency domain signal received on the subcarrier where the pilot is located according to the received time domain received signal, and then according to the pilot subcarrier located on the same OFDM symbol
  • the received frequency domain signal obtains the time domain channel response at the pilot OFDM.
  • the frequency-domain received signal sequence is (_3 ⁇ 4.,. ⁇ ,, ⁇ FREE,. ).
  • FFT fast Fourier transform
  • the frequency-domain received signal sequence is obtained, and then the corresponding time domain channel response is obtained according to the frequency domain received signal sequence, since the frequency domain signal sequence carried by the k-th pilot OFDM symbol is (D k 0 , D kl , D k , N d. J, Therefore, the frequency-domain channel response at the k-th pilot OFDM symbol is ( , ⁇ , " ⁇ ), which is abbreviated as k ,.
  • Step 1502 Extract time-domain channel information at the pilot OFDM symbol according to the time-domain channel response at the pilot OFDM symbol.
  • the time-domain channel information includes path delay, path loss, and the like.
  • the information After obtaining the time-domain channel response at the pilot OFDM symbol, in order to reduce channel noise, the information needs to be analyzed to obtain effective channel information.
  • the simple truncation method which can be used when the channel delay range of the wireless transmission environment is known.
  • the other is the adaptive channel information extraction method.
  • the truncation range can be determined according to the delay extension supported by the system. For example, assuming that the channel delay is at most N sampling points, the pilot OFDM symbol obtained in step 1502 can be directly processed at this time. Time domain channel response ..., ⁇ . ,. ), And the truncation range is slightly larger than the number of sampling points corresponding to the maximum delay of the channel. For example, the truncation range is N, and N, ⁇ N.
  • the time-domain channel at the k-th pilot OFDM symbol obtained at this time is ( C f,, .., ⁇ ,, 0, ⁇ , ()), where the number of '0 is N p , data- N '
  • the adaptive channel information extraction method specifically analyzes the time-domain channel response of the pilot OFDM symbols received continuously for a period of time (,,,,,,,,,,, and ⁇ ), and selects a part of the strongest path as effective
  • the selected effective path need not be continuous. For example, ( c K, ..., c £ iM ) can be selected as the valid channel information for a certain period of time. After determining the effective channel information, use 0 instead of the unselected time domain channel value in the time domain channel response of the pilot OFDM symbol. In this way, the time of the pilot OFDM symbol can be obtained. Domain channel information.
  • the foregoing adaptive channel information extraction method may also be simplified, for example, truncation may be incorporated into the method.
  • the simplified method is called an adaptive truncation method.
  • the method first needs to determine the truncation length N.
  • N the time domain channel at the continuous time pilot OFDM symbol can be firstly reacted.
  • An analysis is performed to determine the region where the energy is concentrated, and the length corresponding to the region is taken as N, where N is the determined truncation length, and N is obtained, and all the corresponding time-domain channel values are obtained, and then 0 is used.
  • the time domain channel response at the pilot OFDM symbol that is, N, all time domain channel values thereafter, thereby determining the time domain channel information.
  • Step 1503 Use time-domain channel information at adjacent pilot OFDM symbols and use a specific interpolation algorithm to estimate time-domain channel information at data OFDM symbols.
  • the time-domain channel information of the channel at the data OFDM symbol ( « 1 , ... , £ ⁇ ,, 0, ..., 0), where s is the number of the data OFDM symbol.
  • ⁇ represents the time-domain channel value at the i-th sampling point at the k + m pilot OFDM symbol, and represents the time-domain channel value at the i-th sampling point at the k * n + j data OFDM symbol
  • n represents the data OFDM symbol between two adjacent pilot OFDM symbols Number of.
  • n two The number of data OFDM symbols between adjacent pilot OFDM symbols.
  • n Represents the number of data OFDM symbols between two adjacent pilot OFDM symbols.
  • Step 1504 Use the time domain channel information at the obtained data OFDM symbol to obtain the Frequency domain channel information at data OFDM symbols.
  • the first processing method is used for channel estimation.
  • this processing process can also be used in other pilot allocation modes, for example, for channel estimation in a pilot allocation mode based on pilot grid points.
  • the specific processing process is similar to the above process. Therefore, the following only processes it. The process is briefly explained.
  • a pilot allocation pattern based on the pilot grid is shown in Figure 16.
  • the specific flow of the first processing method is shown in FIG. 17 and corresponds to the following steps:
  • Step 1701 The receiving end obtains, according to the received time-domain received signal, the frequency-domain received signal received on the subcarrier where the pilot is located.
  • Step 1702 Obtain a time-domain channel response at a corresponding OFDM symbol according to a frequency-domain received signal received on a pilot subcarrier located on the same OFDM symbol.
  • Step 1703 Obtain time domain channel information from the time domain channel symptom.
  • the time domain channel information may be a path delay, a path loss, and the like.
  • Step 1704 Estimate the time-domain channel information at the OFDM symbol adjacent to the OFDM symbol and containing data according to the time-domain channel information at the OFDM symbol including the pilot subcarrier and using a specific interpolation algorithm.
  • Step 1705 Obtain frequency domain channel information at the subcarrier corresponding to the data carrier according to the time domain channel information at the OFDM symbol containing the data.
  • the first processing method has been described in detail above. Since the second processing method is the same as the first One processing method is basically similar, so only the process of channel estimation using the second processing method will be explained. Still taking the distribution of pilot OFDM symbols and data OFDM symbols in the regular time domain as a pilot allocation mode as an example, the detailed processing process of its channel estimation is shown in FIG. 18, which corresponds to the following steps:
  • Step 1801 The receiving end obtains a channel response in the time domain at the pilot OFDM symbol according to the received time domain received signal.
  • This process is the same as step 1501 in the above processing method.
  • Step 1802 Extract time-domain channel information at the pilot OFDM symbol from the time-domain channel response of the channel at the pilot OFDM symbol.
  • the time-domain channel information includes path delay, path loss, and the like.
  • This process is also the same as step 1502 in the above processing method.
  • Step 1803 Use the obtained time-domain channel information at the pilot OFDM symbol to obtain frequency-domain channel information at the corresponding pilot OFDM symbol.
  • Step 1804 Utilize frequency-domain channel information at adjacent pilot OFDM symbols, and use interpolation to estimate frequency-domain channel information at data OFDM symbols.
  • the interpolation method used in step 1804 may be a 2 / -1 primary Lagrangian interpolation method.
  • the following uses the distribution of the irregular pilot OFDM symbols and the data OFDM symbols as a pilot allocation mode as an example to describe the third processing method described above.
  • the distribution of irregular pilot OFDM symbols and data OFDM symbols is shown in Figure '19.
  • the number of data OFDM symbols contained in each two adjacent OFDM symbols can be different.
  • This pilot allocation mode is more suitable for When the channel changes slowly.
  • the receiver uses the third type.
  • the processing method is specifically to estimate the frequency domain channel information of the data OFDM symbol according to the pilot OFDM symbol.
  • the processing process is shown in FIG. 20, specifically It includes the following steps:
  • Step 2001 The receiving end obtains a channel response in the time domain at the pilot OFDM symbol according to the received time domain received signal.
  • Step 2002 Extract time-domain channel information at the pilot OFDM symbol according to the time-domain channel response at the pilot OFDM symbol.
  • the time-domain channel information includes path delay, path loss, and the like.
  • This process is also the same as step 1502 in the above processing method.
  • Step 2003 Use the obtained time-domain channel information at the pilot OFDM symbol to obtain frequency-domain channel information at the pilot OFDM symbol.
  • Step 2004 The obtained frequency domain channel information at the pilot OFDM symbol is directly used as the frequency domain channel information of the data OFDM symbol between the pilot OFDM symbol and the next pilot OFDM symbol.
  • the obtained frequency domain channel information at the pilot OFDM symbol can also be modified, and the modified frequency domain channel information can be used as the frequency of the data OFDM symbol between the pilot OFDM symbol and the next pilot OFDM symbol. Domain channel information.
  • the solution of the present invention can achieve better performance in the case of changing channel environment and high delay.
  • the truncation path number is 32
  • the channel estimation result in the case of Vehicle A channel at 30 kmp is shown in FIG. 21, and the performance loss is less than 0.3 dB
  • the channel estimation results for A channel and 60kmph are shown in Figure 22, and the performance loss is less than l.ldB.
  • the performance loss of the channel estimation obtained by using the solution of the present invention is less than 0.7 dB compared to the ideal channel estimation.

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Abstract

L'invention concerne un procédé d'estimation de voie dans un système OFDM. Le procédé consiste à: obtenir d'abord, sur un côté réception, un signal de réception en domaine fréquentiel reçu par une sous-porteuse dans laquelle est localisé un pilote, sur la base d'un signal de réception en domaine temporel reçu; sur la base du signal de réception en domaine temporel reçu dans la sous-porteuse à pilote dans laquelle le même symbole OFDM est localisé, obtenir des données de voie du domaine temporel au niveau du symbole OFDM; utiliser lesdites données de voie du domaine temporel pour estimer les données de voie du domaine fréquentiel de la sous-porteuse dans laquelle le symbole de données est localisé. Le procédé de l'invention règle la question qui fait apparaître la solution actuelle d'estimation de voie comme occasionnant plus de pertes lorsqu'elle est utilisée pour le système dont le changement de la circonstance de voie est rapide et utilisé pour une voie à retard plus important. La solution de l'invention peut produire une performance préférable dans le cas où le changement de la circonstance de voie est rapide; et améliore efficacement la performance d'une voie à grand retard et l'estimation de voie réelle dans un système OFDM. Cette solution améliore également l'applicabilité d'un système de communication de données relativement à une circonstance de voie, ce qui améliore l'efficience de la transmission de données du système de l'invention.
PCT/CN2005/000756 2004-06-11 2005-05-30 Procede de mise en oeuvre d'une estimation de voie dans un systeme ofdm WO2005122447A1 (fr)

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