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WO2017034236A1 - Procédé et appareil d'émission en diversité - Google Patents

Procédé et appareil d'émission en diversité Download PDF

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Publication number
WO2017034236A1
WO2017034236A1 PCT/KR2016/009186 KR2016009186W WO2017034236A1 WO 2017034236 A1 WO2017034236 A1 WO 2017034236A1 KR 2016009186 W KR2016009186 W KR 2016009186W WO 2017034236 A1 WO2017034236 A1 WO 2017034236A1
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Prior art keywords
antenna array
coded signal
txru
antenna
transmitting
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English (en)
Inventor
Pengfei Sun
Chen QIAN
Bin Yu
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Samsung Electronics Co Ltd
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Samsung Electronics Co Ltd
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Priority claimed from CN201610048551.4A external-priority patent/CN106470064B/zh
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Publication of WO2017034236A1 publication Critical patent/WO2017034236A1/fr
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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
    • H04B7/0408—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas using two or more beams, i.e. beam diversity
    • 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
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
    • 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
    • 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
    • H04B7/0615—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 of weighted versions of same signal
    • H04B7/0617—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 of weighted versions of same signal for beam forming
    • 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
    • H04L1/0606—Space-frequency coding
    • 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
    • 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
    • H04L1/0625—Transmitter arrangements

Definitions

  • the present disclosure relates to wireless communication technologies, and especially to a method and an apparatus for transmitting diversity in a multi-antenna system.
  • the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post LTE System’.
  • the 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60GHz bands, so as to accomplish higher data rates.
  • mmWave e.g., 60GHz bands
  • MIMO massive multiple-input multiple-output
  • FD-MIMO Full Dimensional MIMO
  • array antenna an analog beam forming, large scale antenna techniques are discussed in 5G communication systems.
  • RANs Cloud Radio Access Networks
  • D2D device-to-device
  • CoMP Coordinated Multi-Points
  • FQAM Hybrid FSK and QAM Modulation
  • SWSC sliding window superposition coding
  • ACM advanced coding modulation
  • FBMC filter bank multi carrier
  • NOMA non-orthogonal multiple access
  • SCMA sparse code multiple access
  • the Internet which is a human centered connectivity network where humans generate and consume information
  • IoT Internet of Things
  • IoE Internet of Everything
  • sensing technology “wired/wireless communication and network infrastructure”, “service interface technology”, and “Security technology”
  • M2M Machine-to-Machine
  • MTC Machine Type Communication
  • IoT Internet technology services
  • IoT may be applied to a variety of fields including smart home, smart building, smart city, smart car or connected cars, smart grid, health care, smart appliances and advanced medical services through convergence and combination between existing Information Technology (IT) and various industrial applications.
  • IT Information Technology
  • 5G communication systems to IoT networks.
  • technologies such as a sensor network, Machine Type Communication (MTC), and Machine-to-Machine (M2M) communication may be implemented by beamforming, MIMO, and array antennas.
  • MTC Machine Type Communication
  • M2M Machine-to-Machine
  • Application of a cloud Radio Access Network (RAN) as the above-described Big Data processing technology may also be considered to be as an example of convergence between the 5G technology and the IoT technology.
  • RAN Radio Access Network
  • MIMO Multiple-input-multiple-output technology
  • multi-antenna technology may exponentially increase spectral efficiency of a wireless communication system by utilizing spatial resources, and therefore has become an important technology of cellular communications.
  • transmitting diversity is an effective means of using space-time coding to enhance link reliability.
  • Long term evolution (LTE) systems corresponding to an evolved universal terrestrial radio access (E-UTRA) protocol proposed by the third generation partnership project (3GPP) define various ways of transmitting diversity.
  • a large-scale antenna array (large-scale MIMO, or massive MIMO) system is a main candidate technique of the 5th Generation (5G) cellular communication standards.
  • Large-scale antennas enable a system to use a great number of degrees of freedom of signal processing to dramatically decrease interference among user equipments and interference among cells, and calculation therein is not complex, which may effectively improve the quality of communication links.
  • the large-scale antennas may effectively reduce power consumption of a single antenna unit, and improve energy efficiency of the overall system.
  • Existing experiments have testified possibility of configuring tens or even hundreds of antennas for a base station.
  • An implementation of large-scale antennas in a millimeter wave band may be that a base station configured with a large-scale antenna array uses phase difference among antennas to form extremely narrow transmitting beams to serve a plurality of user equipments when a distance between the antennas is very small; meanwhile, a user equipment may also be configured with multiple antennas to form different gains for different directions of arrival, and may select a receiving beam with a relatively large gain to receive data. If each transmitting beam of the base station serves one user equipment, then interference among the user equipments will be dramatically reduced; and if two neighboring base stations use transmitting waves in different directions to serve their respective user equipments, then interference among the cells will be dramatically reduced.
  • a theoretic analysis result shows that in a large-scale antenna system, if a transmitter knows accurate channel distribution information (CDI) of channels of a user equipment, then resulting signal-to-noise ratios (SNRs) of downlinks and uplinks may increase as the number of antennas increases; and for tens or even hundreds of transmitting antennas, corresponding system capacities thereof may be improved significantly.
  • CDI channel distribution information
  • SNRs signal-to-noise ratios
  • LTE systems Since it is hard to realize multiple antennas transmitting diversity when there are too many antennas, e.g., a lot of challenges to be encountered with when designing space-time code, currently, LTE systems only define transmitting diversity using four antennas for transmission diversity. Therefore, how to realize transmitting diversity in a large-scale antenna system is a field yet to be exploited.
  • a method for transmitting diversity, implemented at a transmitting end, including performing space-time precoding for a digital signal to obtain at least two coded signal streams, and transmitting each coded signal stream using a respective transmitting and receiving unit (TXRU) equipped with a multi-antenna array, in which an antenna array weight used by the respective TXRU to transmit each coded signal stream is one of two sets of antenna array weights, and there are at least two TXRUs using two different sets of antenna array weights.
  • TXRU transmitting and receiving unit
  • the two sets of antenna array weights may be respectively:
  • ⁇ is a central direction of beamforming, d is a distance between antenna units, ⁇ is a wavelength, and N is the number of antenna units in a TXRU;
  • w1 is a N-dimensional vector, and the n th element in w1 is represented as , where 1 ⁇ n ⁇ N;
  • w2 is a N-dimensional vector, wherein first N/2 elements in w2 are the same with first N/2 elements in w1, and last N/2 elements of w2 are opposite numbers of last N/2 elements in w1.
  • the antenna array weight used by the respective TXRU to transmit each coded signal stream varies as time varies.
  • the number of coded signal streams transmitted using a same antenna array weight varies as time varies.
  • the space-time precoding includes a combination of one or more of space-time block coding (STBC), space-frequency block coding (SFBC), cyclic delay diversity (CDD), frequency switch transmit diversity (FSTD), and antenna switching.
  • STBC space-time block coding
  • SFBC space-frequency block coding
  • CDD cyclic delay diversity
  • FSTD frequency switch transmit diversity
  • a transmitter including: a coding module and a transmitting module, in which
  • the coding module is to perform space-time precoding for a digital signal to obtain at least two coded signal streams
  • the transmitting module includes a multi-antenna array and is to transmit each coded signal stream using a respective transmitting and receiving unit (TXRU) equipped with the multi-antenna array, in which an antenna array weight used by the respective TXRU to transmit each coded signal stream is one of two sets of antenna array weights, and there are at least two TXRUs using two different sets of antenna array weights.
  • TXRU transmitting and receiving unit
  • the two sets of antenna array weights are respectively:
  • ⁇ is a central direction of beamforming, d is a distance between antenna units, ⁇ is a wavelength, and N is the number of antenna units in a TXRU;
  • w1 is a N-dimensional vector, and the n th element in w1 is represented as , where 1 ⁇ n ⁇ N;
  • w2 is a N-dimensional vector, wherein first N/2 elements in w2 are the same with first N/2 elements in w1, and last N/2 elements in w2 are opposite numbers of last N/2 elements in w1.
  • the antenna array weight used by the respective TXRU to transmit each coded signal stream varies as time varies.
  • the number of coded signal streams transmitted using a same antenna array weight varies as time varies.
  • the space-time precoding includes a combination of one or more of space-time block coding (STBC), space-frequency block coding (SFBC), cyclic delay diversity (CDD), frequency switch transmit diversity (FSTD), and antenna switching.
  • STBC space-time block coding
  • SFBC space-frequency block coding
  • CDD cyclic delay diversity
  • FSTD frequency switch transmit diversity
  • a transmitting end performs space-time precoding for a digital signal to obtain at least two coded signal streams, and when transmitting each coded signal stream using a respective TXRU equipped with a multi-antenna array, uses one of two sets of antenna array weights, which guarantees that there are at least two TXRUs using two different sets of antenna array weights, so as to realize transmitting diversity in a large-scale antenna system.
  • FIG.1 is a schematic diagram of a multi-antenna system using a hybrid mode of digital antennas and analog antennas;
  • FIG.2 is a schematic diagram of a flow of generating signals according to Embodiment 1 of the present disclosure
  • FIG.3 is a schematic diagram of gains of beams generated according to a differential method of the present disclosure
  • FIG.4 is a schematic diagram of a comparison of bit error rates achieved based on the differential method of the present disclosure and a traditional method in a single path case;
  • FIG.5 is a schematic diagram of a comparison of bit error rates achieved based on the differential method of the present disclosure and the traditional method in the case of a multi-path fading value being 12dB;
  • FIG.6 is a schematic diagram of a comparison of bit error rates achieved based on the differential method of the present disclosure and the traditional method in the case of a multi-path fading value with 6dB decaying;
  • FIG.7 is a schematic diagram of a signal generating flow in Embodiment 3 of the present disclosure.
  • FIG.8 is a schematic diagram of a signal receiving flow in Embodiment 3 of the present disclosure.
  • FIG.9 is a schematic diagram of a signal generating flow in Embodiment 4 of the present disclosure.
  • FIG.10 is a schematic diagram of a structure of a transmitter according to the present disclosure.
  • FIGURES 1 through 10 discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged telecommunication technologies.
  • the present disclosure provides a simple and effective solution of transmitting diversity based on the hybrid multi-antenna structure described in the Background.
  • space-time precoding is performed for a digital signal to obtain at least two coded signal streams.
  • each of the coded signal streams is transmitted by a respective TXRU equipped with a multi-antenna array, in which an antenna array weight used by the respective TXRU to transmit each coded signal stream is one of two sets of antenna array weights, and there are at least two TXRUs using two different sets of antenna array weights.
  • FIG. 1 is a schematic diagram 100 of a multi-antenna system using a hybrid mode of digital antennas and analog antennas.
  • each transmitting and receiving unit TXRU
  • TXRU transmitting and receiving unit
  • Each digital path can be cascaded with four radio frequency paths.
  • This hybrid structure can provide various combinations of antenna transmission modes, e.g., a transmission mode using a baseband path for spatial multiplexing, and meanwhile, can realize a way of transmission by beamforming using multiple analog paths.
  • an implementation of a multi-antenna system based on the structure shown in FIG. 1 is provided.
  • two TXRUs are configured to provide baseband paths, and each of the TXRUs is cascaded with an antenna array consisting of 4 antenna units.
  • ⁇ is a central direction of beamforming
  • d is a distance between antenna units
  • ⁇ is a wavelength
  • N is the number of antenna units in each TXRU.
  • FIG. 2 is a schematic diagram 200 of a flow of generating signals according to the foregoing method. Based on the foregoing method, gains in different directions obtained based on a two-way analog beamforming method can be as shown in FIG. 3.
  • FIG. 3 is a schematic diagram 300 of gains of beams generated according to a differential method of the present disclosure.
  • a gain of a beam 1 in a central direction is the strongest, and meanwhile, the gain of the beam 1 decreases rapidly when deviating from the central direction.
  • a gain of a beam 2 in a central direction is 0, and increases rapidly when deviating from the central direction.
  • the two sets of weights generate differential beams. This means that when a receiving end is not located in a central direction of beamforming, the beam 2 can provide a better channel gain, so as to reduce possibility of the two signal streams encountering with deep fading at the same time.
  • a transmitting end tends not to ideally align a central direction of beamforming with a receiving end due to issues such as estimation errors, delay of feedback, and non-ideal calibration of antennas. Therefore, the proposed method provides beam pattern diversity based on space-time coding of the digital signals. This method can greatly enhance link reliability even if there are errors in beamforming.
  • the foregoing method is only an intuitive embodiment.
  • the method can be expanded to digital space-time precoding of more paths.
  • the coded signal streams can be grouped into multiple groups each of which has two coded signal streams, and beamforming can be performed for two coded signal streams in each group using weights w1 and w2 respectively.
  • a respective antenna array weight used for each coded signal stream can vary as time varies.
  • the coded signal streams may not be grouped, but beamforming can be performed for each coded signal stream using weights w1 and w2 randomly. In this way, the number of coded signal streams using a same antenna array weight can vary as time varies.
  • the differential weight w2 a part of diversity gains can be obtained using any combination of weights.
  • the selected w2 can generate a beam having a direction totally opposite to that generated by w1, and thus the present embodiment is a good choice.
  • data is transmitted in frames, and each frame comprises 14 modulated symbols.
  • STBC space-time block coding
  • the coded signals formed by the two TXRUs using Alamouti coding are:
  • x1 and x2 are adjacent quadrature phase shift keying (QPSK) modulated symbols
  • y p (k) is a k th symbol on a p th TXRU.
  • Data of each frame is divided into 7 blocks to perform Alamouti coding.
  • Each TXRU is connected with 16 transmitting antennas to perform beamforming.
  • a beamforming weight of TXRU#1 is:
  • TXRU#2 a beamforming weight of TXRU#2
  • ⁇ is a central direction of a beam, and is decided by a user’s location.
  • a transmit diversity solution of a traditional millimeter waveband communication system is considered, i.e., antennas connected with each TXRU using a same beamforming weight w1.
  • the following narrow band multi-path channel model can be used:
  • P is the number of multiple paths, is a fading factor on a p th sub-path, and subjects to a zero mean complex Gaussian distribution, is a direction of arrival (DOA) of the p th sub-path, and a vector can be expressed as:
  • FIG. 4 is a schematic diagram 400 of a comparison of bit error rates achieved based on the differential beamforming method of the present disclosure and a traditional method.
  • a decreasing rate of a bit error rate achieved based on the differential beamforming method is prominently faster than that achieved based on the traditional method. This is because that differential beamforming can effectively decrease the possibility of deep fading caused due to error deviation of beamforming directions, so as to obtain an extra diversity gain, and enhance link reliability.
  • FIG. 5 and FIG. 6 are schematic diagrams 500, 600 of comparisons of bit error rates achieved based on the differential method of the present disclosure and the traditional method in the case of the multi-path fading value being 12dB and 6dB, respectively. It can be seen that in the multi-path case, advantages of the differential beamforming-based diversity scheme are not that significant. However, compared to the traditional scheme, it still has a faster decreasing rate of bit error rate, which indicates that the method provided according to the present disclosure achieves a larger diversity gain, and has better reliability over a fading channel.
  • each physical resource block can consist of 12 subcarriers and 14 orthogonal frequency division multiplexing (OFDM) symbols, and respective two neighboring subcarriers can be coded using SFBC. That is, the 12 subcarriers are separated into 6 blocks to be coded using SFBC, then modulated using OFDM, and then transmitted on two TXRUs.
  • OFDM orthogonal frequency division multiplexing
  • a diversity scheme which combines differential beamforming-based beam diversity and space-frequency block coding (SFBC) is provided.
  • SFBC space-frequency block coding
  • a schematic diagram 700 of a signal generating flow in this embodiment is as shown in FIG. 7.
  • a system schedules and transmits data using physical resource blocks (PRBs).
  • PRBs physical resource blocks
  • Each PRB consists of 12 consecutive subcarriers on 14 OFDM symbols.
  • a transmitting end uses a uniformly spaced linear array as an antenna array, and the transmitting end uses a hybrid structure of baseband/radio frequency as shown in FIG. 1.
  • the space-frequency block coding module 705 outputs two information streams in which a first information stream is [x1 -x2 * ] and a second information stream is [x2 x1 * ]. Then a resource mapping operation 710 is performed on the two information streams output from the space-frequency block coding module 705 to map the two information streams to time-frequency resources. Two symbols of each output stream after performing the space-frequency block coding operation on the two adjacent symbols are still mapped to adjacent subcarriers. Afterwards, a multi-carrier modulation operation 715, e.g., OFDM, is performed for each stream after the resource mapping operation, to obtain time-domain signal streams. Finally, different beamforming weight coefficients in different beam array 725 are used for the two time-domain signal streams, to obtain radio frequency signals to be transmitted. To be specific, one of the time-domain signal streams uses a beamforming weight coefficient vector as follows:
  • N is a dimension of each weight coefficient vector, i.e., the number of antenna array units that are needed for carrying out a beamforming operation for each signal stream;
  • d/ ⁇ is a signal wavelength-normalized antenna spacing;
  • angle ⁇ is an angle of departure (AOD), i.e., a transmitting angle.
  • the beamforming weight coefficient vector w1 used by the first signal stream is a N-dimensional vector, and the n ⁇ thelement in the N-dimensional vector is ,where 1 ⁇ n ⁇ N;
  • the beamforming weight coefficient vector w2 used by the second signal stream is a N-dimensional vector, where the first N/2 elements in the N-dimensional vector are the same with the first N/2 elements of the beamforming weight coefficient used by the first signal stream are same, and the last N/2 elements in the N-dimensional vector are opposite numbers of the last N/2 elements of the beamforming weight coefficient used by the first signal stream.
  • the beamforming weight coefficient vector used by the first signal stream is a sum beam
  • the beamforming weight coefficient vector used by the second signal stream is a differential beam of the sum beam.
  • the transmitting end has knowledge of priori information of the transmitting angle. However, due to estimation error, channel variation, mobility of UE, and the like, there is a certain deviation between priori information and an actual orientation of the UE.
  • reference signals need to be inserted for channel estimation.
  • the reference signals are inserted after the space-frequency block encoding operation and before the multi-carrier modulation operation, and are configured to estimate an equivalent channel for each signal stream after going through beamforming at the transmitter end, a channel, and a radio frequency front end at the receiving end.
  • Orthogonal pilot signals are inserted into the two signal streams, and the like, using orthogonal time-frequency resources to transmit the reference signals, or using orthogonal sequences as the reference signals on a same time-frequency resource.
  • the beamforming weight coefficient used by the first signal stream is a sum beam weight coefficient in sum beam array 720
  • the beamforming weight coefficient used by the second signal stream is a differential beam weight coefficient of the sum beam in differential beam array 725.
  • FIG. 8 is a schematic diagram 800 of a signal receiving flow in a differential beamforming diversity scheme which combines SFBC.
  • the receiving end 805 performs channel estimation for the two links based on the reference signals, to decode space-frequency blocks. After the receiving end receives a signal, it first performs a carrier demodulation operation 810 for the received signal, then performs a space-frequency block decoding operation 815 to obtain output data, and then carries out a subsequent channel demodulation step.
  • the system of the receiving end shown in Fig.8 has a similar structure as that of a traditional system using SFBC, which indicates that the scheme provided according to the present embodiment is transparent to the receiving end, and has relatively small influence on the receiving end.
  • the scheme provided according to the present embodiment provide better protection in a beam direction estimation deviation aspect.
  • Embodiment 4 is a diagrammatic representation of Embodiment 4:
  • a scheme of combining differential beamforming-based beam diversity and cyclic delay diversity is provided.
  • a scheme diagram 900 of a signal transmitting flow of the present embodiment is shown in FIG. 9.
  • CDD generates two links in which a first link is an original link without cyclic delay being performed, and a second link is a link with cyclic delay being performed.
  • the system schedules and transmits data through physical resource blocks (PRBs) in which each PRB consists of consecutive 12 subcarriers on 14 OFDM symbols.
  • PRBs physical resource blocks
  • each PRB consists of consecutive 12 subcarriers on 14 OFDM symbols.
  • a transmitting end uses a uniformly spaced linear array as an antenna array.
  • an input signal is a symbol stream after coding and constellation modulation operations, and the symbol stream is divided into two links after a multi-carrier modulation operation 905.
  • a signal on the first link is added 910 with a cyclic prefix (CP), and then a beamforming operation is performed to obtain a radio frequency signal.
  • a cyclic shift operation is first performed for the signal on the second link, and then the signal on the second link is added 925 with a CP and performs a beamforming operation to obtain a radio frequency signal to be transmitted on the second link.
  • this way to generate cyclic delay 920 through performing a cyclic shift operation on a time-domain signal is equivalent to multiplying each frequency-domain subcarrier by a phase factor, i.e., a phase factor multiplied by a subcarrier k is , where , and N FFT is the number of fast Fourier transform (FFT) points, and d cdd is an amount of time-domain equivalent cyclic shift.
  • the method of multiplying a phase shift factor in a frequency domain needs to separate a frequency-domain signal into two same streams before performing a multi-carrier modulation operation on it.
  • a multi-carrier modulation operation and a beamforming operation are performed directly, and on a second link, a phase shift factor is multiplied, and then a multi-carrier modulation operation and a beamforming operation are performed. Processing in time domain and processing in frequency domain are equivalent.
  • the first link uses a beamforming weight coefficient as follows:
  • the second link uses a beamforming weight coefficient as follows:
  • N is a dimension of each weight coefficient vector, i.e., the number of antenna array units that are needed for carrying out a beamforming operation for each signal stream;
  • d/ ⁇ is a distance between antenna units with signal wavelengths being normalized;
  • angle ⁇ is a direction in which a beam leaves the antenna array, i.e., a transmitting angle.
  • the beamforming weight coefficient w1 used by the first signal stream is a N-dimensional vector, and the n th element in the N-dimensional vector is , where 1 ⁇ n ⁇ N;
  • the beamforming weight coefficient w2 used by the second signal stream is a N-dimensional vector, where the first N/2 elements in the N-dimensional vector w2 are the same with the first N/2 elements in the beamforming weight coefficient w1 used by the first signal stream are same, and the last N/2 elements in the N-dimensional vector w2 are opposite numbers of the last N/2 elements in the beamforming weight coefficient w1 used by the first signal stream.
  • the beamforming weight coefficient used by the first signal stream is a sum beam weight coefficient in sum beam array 915
  • the beamforming weight coefficient used by the second signal stream is a differential beam weight coefficient of the sum beam in differential beam array 930.
  • the transmitting end needs to insert reference signals.
  • a reference signal is inserted before a signal is processed, and is processed in a same way as that for a data signal, used for estimating an equivalent information coefficient after going through cyclic delay processing at the transmitting, an actual physical channel, a front end of the receiving end.
  • the receiving end estimates an equivalent channel according to a reference signal, and uses an estimation result to demodulate data. First a multi-carrier demodulation operation is performed for a received data stream, then an equalization operation of a single tap is performed combined with a channel estimation result, and then constellation mapping demodulation and channel decoding operations are performed, to obtain an estimation of a transmitted bit stream.
  • the two links use a sum beam and a differential beam in a same direction, which, compared with the traditional scheme of using beams in different directions, is able to better protect beam estimation deviation, and provide a higher degree of space diversity.
  • the differential beamforming-based beam diversity scheme not only can be combined with a single space-time coding technique, but also can be combined with multiple space-time coding techniques, for example, first combining SFBC and FSTD, and then combining the differential beamforming-based beam diversity scheme.
  • Fig.10 shows a structure of the transmitter 1000 which includes a coding module 1005 and a transmitting module 1010.
  • the coding module 1005 (i.e., coder) is to perform space-time precoding for a digital signal to obtain at least two coded signal streams.
  • the transmitting module 1010 (i.e., transmitter) includes a multi-antenna array, and is to use TXRUs equipped with the multi-antenna array to transmit the coded signal streams, in which an antenna array weight used by a respective TXRU to transmit a coded signal stream is one of two sets of weights, and there are at least two TXRUs using different sets of weights.
  • the two sets of weights can be respectively:
  • ⁇ is a central direction of beamforming, d is a distance between antenna units, ⁇ is a wavelength, and N is the number of antenna units in each TXRU;
  • the beamforming weight coefficient w1 used by a first probing signal is a N-dimensional vector, and the n th element in the N-dimensional vector is , where 1 ⁇ n ⁇ N;
  • the beamforming weight coefficient w2 used by a second probing signal is a N-dimensional vector, where the first N/2 elements in the N-dimensional vector w2 are the same with the first N/2 elements in the beamforming weight coefficient w1 used by the first probing signal are same, and the last N/2 elements in the N-dimensional vector w2 are opposite numbers of the last N/2 elements in the beamforming weight coefficient w1 used by the first probing signal.
  • the antenna array weight used by each TXRU to transmit each coded signal stream can vary as time varies.
  • the number of coded signal streams transmitted using a same antenna array weight can vary as time varies.
  • the space-time precoding can include a combination of one or more of STBC, SFBC, CDD, FSTD, and antenna switching.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Radio Transmission System (AREA)

Abstract

La présente invention concerne un procédé et un système de communication utiles pour faire converger un système de communication de cinquième génération (5G) permettant de prendre en charge des débits de données élevés supérieurs à ceux d'un système de quatrième génération (4G) à l'aide d'une technologie pour l'Internet des objets (IoT). La présente invention peut s'appliquer à des services intelligents basés sur la technologie de communication 5G et la technologie liée à l'IoT, tels une maison intelligente, un bâtiment intelligent, une ville intelligente, une voiture intelligente, une voiture connectée, des soins de santé, l'enseignement numérique, le commerce de détail intelligent et les services de sécurité des biens et des personnes. D'après un procédé d'émission en diversité mis en œuvre à une extrémité d'émission, un précodage spatio-temporel est effectué sur un signal numérique de façon à obtenir au moins deux flux de signal codés. Puis chaque flux de signal codé est émis à l'aide d'une unité d'émission et de réception respective (TXRU) équipée d'un réseau multi-antenne. Une pondération du réseau d'antennes utilisée par la TXRU respective pour émettre chaque flux de signal codé est un des deux ensembles de pondérations du réseau d'antennes. Au moins deux TXRU utilisent deux ensembles différents de pondérations du réseau d'antennes. La présente invention concerne également un émetteur correspondant. La présente invention permet de réaliser une émission en diversité dans un système d'antennes à grande échelle.
PCT/KR2016/009186 2015-08-21 2016-08-19 Procédé et appareil d'émission en diversité Ceased WO2017034236A1 (fr)

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CN201610048551.4A CN106470064B (zh) 2015-08-21 2016-01-25 发送分集方法及设备

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CN111786706A (zh) * 2020-07-02 2020-10-16 电子科技大学 一种联合信道信息获取和波束赋形方法
CN113238212A (zh) * 2021-04-15 2021-08-10 西安电子科技大学 基于空时编码的频率分集阵列雷达距离分辨率增强方法
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CN116599561A (zh) * 2023-02-10 2023-08-15 北京环佳通信技术有限公司 一种无线自组网多输入多输出传输方法

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