WO2006008305A1 - Verfahren zur signalübertragung in einem kommunikationssystem - Google Patents
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- WO2006008305A1 WO2006008305A1 PCT/EP2005/053508 EP2005053508W WO2006008305A1 WO 2006008305 A1 WO2006008305 A1 WO 2006008305A1 EP 2005053508 W EP2005053508 W EP 2005053508W WO 2006008305 A1 WO2006008305 A1 WO 2006008305A1
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- sequences
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- ofdm
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
- H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
- H04B7/0684—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission using different training sequences per antenna
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/0413—MIMO systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/02—Arrangements for detecting or preventing errors in the information received by diversity reception
- H04L1/06—Arrangements for detecting or preventing errors in the information received by diversity reception using space diversity
- H04L1/0618—Space-time coding
- H04L1/0637—Properties of the code
- H04L1/0668—Orthogonal systems, e.g. using Alamouti codes
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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
- H04L25/0204—Channel estimation of multiple channels
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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
- H04L25/0224—Channel estimation using sounding signals
- H04L25/0226—Channel estimation using sounding signals sounding signals per se
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- 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
- H04L27/2602—Signal structure
- H04L27/261—Details of reference signals
- H04L27/2613—Structure of the reference signals
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- 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
- H04L27/2602—Signal structure
- H04L27/261—Details of reference signals
- H04L27/2613—Structure of the reference signals
- H04L27/26136—Pilot sequence conveying additional information
Definitions
- the invention relates to a method for signal transmission in a communication system, in particular in the context of a so-called MIMO-OFDM signal transmission.
- various methods of resource allocation and multiplexing are used.
- various frequency channels are realized by the FDM method (Frequency Division Multiplex).
- FDM method Frequency Division Multiplex
- a broad frequency spectrum is divided into many frequency channels separated in the frequency range, each having a narrow bandwidth, resulting in a frequency channel grid defined by the distances of the carrier frequencies.
- several subscribers on different frequency channels can thereby be served simultaneously and the resources adapted to individual needs of the subscribers.
- a sufficient distance between the frequency channels ensures that interference between the channels can be reduced and controlled.
- OFDM-based Signalübertra ⁇ supply Orthogonal Frequency Division Multiplexing
- OFDM performs a block modulation in which a block with a number of information symbols is transmitted in parallel on a corresponding number of subcarriers. This can take place in radio communication systems in extension of existing systems of the third generation, for example UMTS, and / or as independent systems based on WLAN (Wireless Local Area Network), for example HiperLan / 2.
- WLAN Wireless Local Area Network
- a further development based on the OFDM transmission relates to a combination of OFDM and the so-called MIMO (Multiple Input Multiple Output), ie transmission and reception over a plurality of paths using in each case a plurality of transmitting and receiving antennas at the communicating stations.
- MIMO-OFDM Multiple Input Multiple Output
- the transmission channel is area orthogonalized by the OFDM component in the frequency, which for each Unter ⁇ carrier individually a non-frequency-selective so-called "flat" channel is created.
- Subcarrier based can ver ⁇ tively simple algorithms for the "flat" MIMO Ka can be used to separate the spatially superimposed data streams at the receiving end.
- Basic Algo ⁇ algorithms for the described combination of MIMO and OFDM are, for example, GG Raleigh and JM Cioffi, "tio spa-Temporal Coding for Wireless Communications", IEEE Trans.Comm., Vol. 46, No. 3, 1998, known.
- the object of the invention is to provide a method and system components which enable real-time processing in a MIMO-OFDM transmission with high data rates.
- This object is achieved by the features of the independent patent claims. Further developments of the invention can be taken from the respective dependent claims
- a transmitting station of a communica ⁇ tion systems at least two transmit antennas on, dimensional via the Sig ⁇ be det gesen- having an antenna individual training sequence wherein the training sequences are designed such that the transmission antennas beginnings sequence at the receiving end by means of the Trai ⁇ are identifiable.
- a low-complexity, and thus real-time capable receiving side channel estimation by means of a correla ⁇ tion allows the time domain.
- the method according to the invention is advantageously used for a MIMO-OFDM transmission.
- a length of the training sequences is selected as a function of the number of transmission antennas.
- the receiving-side estimation error can advantageously be kept constant.
- the length of the training sequence should advantageously be negotiated before a MIMO OFDM transmission is set up between the transmitting and the receiving station.
- the training sequences are modulated with individual orthogonal codes, whereby the training sequences of the antennas in the time domain are mutually orthogonal.
- This code multiplex approach advantageously makes it possible to minimize the receiver-side estimation error in the channel estimation.
- Hadamard sequences known as orthogonal codes are preferably used which, because of their recursive structure, again form orthogonal sequences even with a variation of the sequence length.
- the training sequences are each formed exclusively from binary values for the real and / or imaginary part.
- multiplication operations are replaced by more cost-effective addition and subtraction operations.
- the training sequences are scrambled in the frequency domain, in particular by multiplication by a respective binary sequence.
- the advantageous binary structure of the preamble according to the previous development is retained, and the dynamics of the transmission signal are advantageously limited.
- the real and imaginary components of a transmission signal with a jeweili ⁇ gene sequence marks a set of orthogonal sequences, at the receiving end, a correction imbalance between real and imaginary parts is made possible by means of the.
- FIG. 2 shows real and imaginary parts of a training sequence for a second transmitting antenna
- FIG. 3 shows a frequency-time grid with a reuse of correlation circuits according to the invention
- 6 shows a pipeline structure of a matrix-vector multiplication unit for each four on and off ⁇ gears
- 7 shows address fields for addressing weight matrices in an FPGA
- FIG 8 shows a transmitting device
- FIG 9 a receiving device.
- the system can be implemented on a hybrid software radio platform, which consists of an FPGA and one or more DSPs.
- a low-cost implementation is particularly advantageous for cost-effective use in various applications, such as for wireless local area networks (WLANs) with very high data rates of 100 Mbit / s to 1 Gbit / s, for a so-called fixed-wire ⁇ loose subscriber connection (FWA - fixed wireless access) or to increase the data rate in the wired subscriber access area, such as DSL (digital subscriber line).
- WLANs wireless local area networks
- FWA - fixed wireless access FWA - fixed wireless access
- DSL digital subscriber line
- a reception side synchronizer and the determination may be a frequency offset NEN the ⁇ used for all transmit antennas to an average ⁇ Sig nal-to-noise ratio - to maximize the receiver (SNR signal noise ratio).
- new preambles are defined as training sequences for the reception-side channel estimation or determination of channel coefficients, which a distinction of the channels of different Sendean ⁇ antennas at the receiving antennas and a simplified processing allow.
- the aim of the definition according to the invention of the preamble or training sequence for channel estimation is to make possible an estimation of a transmission channel as far as possible without interpolation errors .
- Estimation errors should arise only due to receiver noise, and the size of the error can be influenced by varying the sequence length.
- a principle the same training sequence wherein the ge ⁇ entire training sequence has a variable number K aufeinan ⁇ the following OFDM symbols is distributed, wherein K, eg, can amount to 64 to.
- the correlation in the time domain is considered in a first step.
- a received signal at the i-th receiving antenna on the n-th subcarrier is given as a sum over all transmitted signals on this subcarrier multiplied by the respective channel coefficients
- index k consecutively numbers the consecutive OFDM symbols, n the channel coefficients to be estimated, and n k the receiver noise.
- the power of the binary training sequences ⁇ nk ⁇ 2 j_ s ⁇ is normalized to 1 at each point in time t k .
- Statistics and amplitude of the Gaussian noise are cation remains otherwise unchanged by the Multipli ⁇ with a so normalized complex number. If now the noise as a random process
- N Tx / (K * SNR) the variance of the estimation error is also known (N Tx / (K * SNR)), and N is a complex Gaussian random number with variance 1.
- a third step concerns scrambling in the frequency domain.
- Use foregoing same sequence on all sub-carriers would result in each OFDM symbol all subcarriers would be occupied by a moving ⁇ chen value.
- the inverse fast Fourier transform (IFFT) on the transmit side would thus synthesize a short Dirac pulse with an amplitude N c .
- IFFT inverse fast Fourier transform
- a scrambling of the sequences in the frequency ⁇ is performed frequency range according to the invention.
- this can be achieved, for example, by means of a multiplication with a subcarrier-individual binary sequence.
- the binary structure of the preamble which has previously been identified as advantageous, is advantageously maintained, and the dynamics of the transmission signal are again restricted to a common range.
- the scrambling before the channel estimation has to be reversed by a corresponding change of sign of the sequence.
- a fourth step deals with a correction of the so-called IQ-imbalance.
- the imbalance disadvantageously causes a coupling between received signals in the upper and lower sideband.
- the corresponding transmit and receive circuits include an IQ imbalance which estimates from the signal processing ge ⁇ and must be compensated.
- the calibration can be performed relatively easily, but explicit knowledge of the parameters of the imbalance must be available.
- the Kanal ⁇ is corrected estimate, but no explicit know ⁇ nisse the parameters must be present.
- a calibration is performed in advance for each individual transmitter and receiver and the IQ unbalance is corrected separately in each baseband unit.
- this disadvantageously results in considerable costs for the calibration, which are contrary to a practical realization.
- each transmit signal in the time domain is tagged with their own sequence from the same orthogonal set of sequences, and the IQ imbalance is corrected by MIMO real-valued signal processing, where each I and Q branch ei ⁇ nes each transceiver is assumed as a virtual antenna.
- the system works in this case with a real channel matrix with twice the number of virtual transmit and receive antennas.
- each of the symbols of the preamble is split into two symbols so that only subcarriers in the upper sideband are used during the odd symbols.
- the direct channel coefficients are then estimated in the upper sideband, whereas in the lower sideband, the cross-talk coefficients are estimated.
- only the subcarriers of the lower sideband are used in order to estimate the direct channel coefficients.
- O x are sequences from an orthogonal set of sequences, for example known Hadamard sequences.
- O x the x-th row from the square Hadamard matrix are used.
- 2-N Tx sequences (second approach) can be used. Due to the variable length of the training sequences, the quality of the channel estimation at various antenna arrays may advantageously adjusted according to equation (7), and requests the transmission method used with respect to the Qua ⁇ formality of the channel estimation are met.
- mene transmitting antenna according to the equation (8-11) Darge ⁇ presents.
- a subcarrier or frequency index is plotted on the vertical axis, and a time index in units of 4us is plotted on the horizontal axis.
- Each column corresponds to an OFDM symbol and each line corresponds to a subcarrier.
- the Hiperlan / 2 Standard is used for the training sequence represents a maximum darge An ⁇ number of 64 OFDM symbols. Of the 64 possible subcarriers shown, only 52 are used in the example.
- the real part of the first antenna remains constant over time on all subcarriers, which is a characteristic feature of the first Hademamord sequence.
- the imaginary part changes its sign from OFDM symbol to OFDM symbol.
- the real and imaginary change only in JE second OFDM symbol, where the changes are, however gegen ⁇ shifted one symbol duration each.
- the scrambling frequency is based on itself unre ⁇ regularly changing sign illustrated.
- Equation (3) N Tx -N Rx -N c complex correlations according to Equation (3) are required. If an individual circuit were implemented for each correlation, the limits of currently available FPGAs would be exceeded. According to the equation (3) must continue a correlation can be carried out over several consecutive OFDM symbols.
- each column corresponds to an OFDM symbol (time index) and each row corresponds to a subcarrier (subcarrier index).
- the recipient ger went into consideration the receiver side.
- the recipient ger went into consideration the receiver side.
- the recipient ger went into consideration the receiver side.
- the recipient ger went into consideration the fast Fourier transform (FFT) outputs the received signals on the respective sub-carriers from serial, wherein real and imaginary parts are ⁇ tig available gleichzei. This is shown in FIG 3 by means of a zig-zag up and down line.
- the correlation takes place in each sub-carrier OFDM symbol for OFDM symbol, ie in the time domain.
- the aim of the implementation is now to reuse the correlation circuits as possible for all subcarriers to be considered.
- the transmission-side scrambling is reversed, for example by means of a sign change of the received signal corresponding to the sequence S n .
- Closing at ⁇ the fact is exploited that all Unterträ ⁇ modulated ger a transmitting antenna in the time domain with the same sequence.
- the same correlation circuit can finally be used for all subcarriers; only the respective intermediate results must be stored in a memory of length N c .
- the last intermediate result for subcarrier n is read from the memory (first operand), depending on the current value of the Hadamard sequence, if appropriate, the sign Emp ⁇ of capture signal (second operand) in this sub-carrier for the ak ⁇ Tuelle OFDM symbol changed, adds the two values and the result is again stored in memory.
- the first two steps can be performed in parallel, but the last two steps can be performed sequentially.
- the process described can be carried out in several parallel pipelines in each case sequentially for a plurality of successive subcarriers.
- one pipeline each is responsible for a subcarrier, wherein the individual steps in a pipeline are executed one after the other.
- the channel estimation in the individual pipelines can be initiated successively in accordance with the number of the subcarrier.
- the channel estimation is perfect in that for each subcarrier there is a result without systematic error.
- the inventive method thus produces no interpolation part way before ⁇ .
- the result of the wetting is Shut ⁇ immediately after the C-preamble or training sequence before ⁇ for further processing, and it meets the process of the initially mentioned article by Stüber et al not result in additional delays.
- the receiver still has one Matrix inversion and an IFFT used to transmit pilot signals only on a reduced number of subcarriers must sen.
- weight matrices W n are given by the pseudoinverse of the channel matrices at the n-th subcarrier:
- the matrix inversion in equation (10) can be calculated using known algorithms, such as Gauss-Jordan, but special methods such as Greville can be used which lead directly to the pseudoinverse matrix.
- Gauss-Jordan special methods
- Greville can be used which lead directly to the pseudoinverse matrix.
- these algorithms are difficult to translate directly into an FPGA.
- a simpler implementation, however, is possible in a conventional microprocessor or DSP. This results in continued high demands on both the coupling between DSP and FPGA, as well as to the Pro ⁇ programming of the DSPs, since the channel coefficients for each sub-carrier within a period of typi ⁇ shear, less than lms re-estimated and tracked so ⁇ as the weight matrices must be calculated.
- the results of the channel estimation have to be read into a DSP which, as mentioned above, requires a fast coupling between DSP and FPGA.
- Practical OFDM systems typically use a fairly large number of subcarriers.
- the HiperLan / 2 and IEEE 802.11a standards use 48 subcarriers
- the IEEE 802.16 standard uses 256 subcarriers and future radio communi- Fourth generation cation systems are expected to use 512 to 1024 subcarriers.
- 16 ⁇ 48 768 channel coefficients having a resolution of, for example, 12 bits must be transmitted while correcting the IQ imbalance.
- this amount of data can be transmitted in a time of 38 ⁇ s.
- the required time is already 307 ⁇ s, and for example, 200 subcarriers, the required time is 1.3 ms.
- a wider ⁇ terer bus and possibly a much higher effective clock frequency are required. The fastest possible access of the DSP to registers in the FPGA is therefore necessary.
- each DSP being responsible, for example, for a specific subgroup of subcarriers and individually connected to the FPGA.
- An exemplary realization in the form of a star structure with an FPGA as a node is shown in FIG.
- the DSP first writes the results back to a buffer from where they are copied to registers used by the data reconstruction at the next possible time when no data is being transferred, generally during the transmission of preambles.
- weight matrices are calculated and results are transferred back to the FPGA. Since the weight matrices for all subcarriers, as mentioned above, have to be calculated in a very short period of typically 1 ms in order to be able to follow a temporal change of the channel coefficients, very high processing powers are required. Theoretical values are about 100 million floating-point operations per second for 48 subcarriers and four transmitting and receiving antennas each. Since practical values with non-optimized C code are usually much higher, the implementation of the algorithms should be adapted as well as possible to the internal structure of the DSP in order to come as close as possible to these theoretical values.
- the computing times can be reduced by means of hardware-optimized DSP codes by almost two orders of magnitude compared to a non-optimized C code.
- These optimizations allow forth in part by way of a realization currently discussed system, such as an extension of IEEE 802. lla standards by MIMO-OFDM, based on a current or less verheg ⁇ Barer DSPs. Results of such an optimization are shown by way of example in FIG. On the vertical axis is logarithmically a total time in ms for 48 subcarriers, and carried on the horizontal axis a number of transmit antennas auf ⁇ .
- MVME matrix vector multiplication unit
- this unit multiplies a valid for the current sub-carrier weight matrix W ⁇ n with a current received vector after the glei chung (1) in one cycle step.
- This can advantageously be achieved by means of a pipeline structure, as shown by way of example in FIG.
- All occurring multiplications are carried out in parallel, for which, due to the complex operands 4 * N Tx * N Rx, preferably multipliers are used which are directly implemented in hardware and which are already implemented in a large number in currently available FPGAs.
- the required additons are executed in pairs until an end result is obtained.
- the cascade of additions in FIG. 6 is generally similar to the co-principle in sports competitions. Effectively, a matrix-vector multiplication is thus carried out in each clock step, which advantageously enables real-time realization with simultaneously high data rates.
- the above-mentioned matrix-vector multiplication unit can also be used in a sub-carrier sub-carrier MIMO-OFDM system.
- the weight matrices W n are first exchanged for this purpose, for example by means of a suitable addressing of the operands in a correct order.
- an address selected for this register which allows a simple switching between weight matrices of ein ⁇ individual subcarrier, for example by means of a counter, he ⁇ allows.
- a possible addressing is shown by way of example in FIG. 7, but the individual fields can be exchanged as desired in the same way.
- FIG. 8 shows an exemplary integration of a transmitter.
- a parallel connection of two OFDM transmission lines is realized.
- Data data by means of a one ⁇ direction to the serial-parallel conversion S / P in several partial data streams split and independently in a device l / E interleaved and encoded (interleaving / Encoding), and optionally additionally punctured to reduce the data rate.
- a common interleaving and coding for the partial data streams can be performed in the same way. All for one
- important signals such as the A-, B- and C-preamble according to the invention, are generated in the Tx FPGA and performed in time division multiplex with the data signals to ⁇ mer together. This is done in a framing and modulation device F / M (framing / modulation), in which the transmission frames consisting of the individual signal components are formed and modulated.
- F / M framing and modulation device
- an inverse fast Fourier transform IFFT and it adds a cyclic prefix into the time domain signal is ⁇ .
- the preambles can also be inserted into the time domain signal as complex sample values.
- the di ⁇ gitalen transmission signals are then converted by digital-analog-log converter D / A into analogue signals in base band BB, and modulated by IQ-modulators in the transmission means Tx to the carrier frequency before a MIMO channel education dend transmission antennas are transmitted via the radio interface.
- a line-bound transmission of the analog signals can take place in the same way.
- Analog receive signals of the MIMO channel are downconverted in respective receive antennas downstream receiver devices Rx into the baseband BB, and the complex baseband signals are then digitized in respective analog-to-digital converters A / D.
- the Empfangseinrich ⁇ obligations Rx are, for example, directly ab includekonvertie ⁇ -saving receiver.
- the corresponding A and B preamble signals are evaluated in the time domain in a synchronization device SYNC.
- the other signals pass to an unshown correction of the frequency offset and, where appropriate, ⁇ an estimate of the signal strength of a Fast Fourier Transform FFT.
- the signals leave the fast Fourier transformation to simplify the implementation, preferably ordered by subcarrier.
- the signals are supplied in parallel to a channel estimator CE (Channel Estimation) and a detection device DET.
- CE Channel Estimation
- the channel estimation is carried out on the previously signed ⁇ be inventive structure of the C-preamble or training sequence.
- the digital estimation results for the matrices H n are read into one or more DSPs, which may, for example, be implemented as part of the FPGA Rx-FPGA.
- the weight matrices W n are then stored in register pages according to the individual subcarriers.
- the channel estimation can be carried out in the time or frequency domain. Estimates in the time domain can be realized more efficiently in terms of the number of variables to be estimated, since the number of samples in the gel is significantly smaller than the number of subcarriers. However, there is currently no adequate time-domain estimator available and implemented in an FPGA. It should also be noted that the number of channel coefficients for estimates in the frequency domain far exceeds the channel coefficients required for so-called flat-fading channels.
- a MVME For the data reconstruction, a MVME, a linear MMSE (Minimal Mean Square Error) or in the general case a so-called flat-fading MIMO detector can be used as the detection device DET.
- the MVME performs, in quasi real-time, a multiplication of all the components of the reception vector from equation (1) with the weight matrix W n belonging to the current carrier index n .
- the corresponding matrix W n is selected from the corresponding register pages, which is symbolized in FIG. 9 by a switch which can be switched between the register pages.
- the signals thus reconstructed are subsequently decoded in a decoding and deinterleaving device, and the transmission-side interleaving is undone.
- P / S for parallel-serial conversion all partial data streams are brought together again and are available as data data for further processing.
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Abstract
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US11/572,492 US20080137760A1 (en) | 2004-07-20 | 2005-07-20 | Method For Transmitting Signals in a Communication System |
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DE102004035018A DE102004035018A1 (de) | 2004-07-20 | 2004-07-20 | Verfahren zur Signalübertragung in einem Kommunikationssystem |
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KR (1) | KR20070030291A (de) |
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WO2007013560A1 (ja) * | 2005-07-29 | 2007-02-01 | Matsushita Electric Industrial Co., Ltd. | マルチキャリア通信における無線通信基地局装置、無線通信移動局装置、および、パイロット信号系列割当方法 |
KR101526015B1 (ko) * | 2008-11-25 | 2015-06-05 | 엘지전자 주식회사 | 무선통신 시스템에서 데이터 전송방법 |
US10499421B2 (en) * | 2014-03-21 | 2019-12-03 | Qualcomm Incorporated | Techniques for configuring preamble and overhead signals for transmissions in an unlicensed radio frequency spectrum band |
WO2017004836A1 (zh) * | 2015-07-09 | 2017-01-12 | 华为技术有限公司 | 一种数据检测方法和装置 |
CN110868264B (zh) * | 2018-08-28 | 2021-12-10 | 北京紫光展锐通信技术有限公司 | 时分双工收发机及其校准方法、可读存储介质 |
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GB2376601B (en) * | 2001-06-15 | 2004-02-25 | Motorola Inc | Transmission diversity in a cellular radio communication system |
DE10140532A1 (de) * | 2001-08-17 | 2003-02-27 | Siemens Ag | Verfahren zum Übertragen eines globalen Pilotsignals zwischen Stationen eines Funk-Kommunikationsystems und Station dafür |
US7280467B2 (en) * | 2003-01-07 | 2007-10-09 | Qualcomm Incorporated | Pilot transmission schemes for wireless multi-carrier communication systems |
-
2004
- 2004-07-20 DE DE102004035018A patent/DE102004035018A1/de not_active Withdrawn
-
2005
- 2005-07-20 CN CNA2005800243036A patent/CN101019339A/zh active Pending
- 2005-07-20 KR KR1020077001708A patent/KR20070030291A/ko not_active Application Discontinuation
- 2005-07-20 US US11/572,492 patent/US20080137760A1/en not_active Abandoned
- 2005-07-20 WO PCT/EP2005/053508 patent/WO2006008305A1/de active Application Filing
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US6018555A (en) * | 1995-05-01 | 2000-01-25 | Intermec Ip Corp. | Network utilizing modified preambles that support antenna diversity |
US20030016621A1 (en) * | 2001-05-21 | 2003-01-23 | Ye Li | Optimum training sequences for wireless systems |
EP1414177A1 (de) * | 2002-09-26 | 2004-04-28 | Kabushiki Kaisha Toshiba | Kanalschätzung für OFDM unter Verwendung orthogonaler Trainingssequenzen |
Non-Patent Citations (1)
Title |
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CHANGHO SUH ET AL: "Preamble Design for Channel Estimation in MIMO-OFDM Systems", GLOBECOM'03. 2003 - IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE. CONFERENCE PROCEEDINGS. SAN FRANCISCO, DEC. 1 - 5, 2003, IEEE GLOBAL TELECOMMUNICATIONS CONFERENCE, NEW YORK, NY : IEEE, US, vol. VOL. 7 OF 7, 1 December 2003 (2003-12-01), pages 317 - 321, XP010677895, ISBN: 0-7803-7974-8 * |
Also Published As
Publication number | Publication date |
---|---|
US20080137760A1 (en) | 2008-06-12 |
CN101019339A (zh) | 2007-08-15 |
KR20070030291A (ko) | 2007-03-15 |
DE102004035018A1 (de) | 2006-02-16 |
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