76 results about "Zero-forcing precoding" patented technology

The invention provides a precoding transmission method for a multi-input and multi-output system, which comprises: a mobile station supposes an emission matrix as a unitary matrix, an MMSE receiver is used for signal combination, an equative channel is calculated, CQI and CDI are obtained and are fed back a base station; according to a channel direction index and channel quality information fed by the mobile station, the base station obtains a zero-forcing precoding emission matrix or a regulated zero-forcing precoding emission matrix corresponding to partial or total possible user combination, carries out multiuser scheduling operation and determines the scheduled user combination; and the base station utilizes the zero-forcing precoding emission matrix or the regulated zero-forcing precoding emission matrix corresponding to the scheduled user combination to carry out precoding and emission; and a scheduled user carries out MMSE receiving. The method reduces error of channel feedback, therefore effectively promoting the utilization ratio of frequency spectrum of the system.

The invention discloses a multi-user generalized space modulation system linearity zero-forcing precoding method. The method comprises the following steps: establishing a multi-user generalized space modulation system, and grouping antennas at a link sending end, wherein each group of sending antennas serve one receiving end by use of generalized space modulation; performing dimension reduction on a channel gain matrix of a sending signal matrix in a system so as to obtain an equivalent channel gain matrix and an equivalent sending signal matrix; and by use of a dimension reduction matrix, performing zero-forcing precoding processing on the sending signal matrix at the sending end, and transmitting signals by use of the equivalent channel gain matrix so as to eliminate interference between users and interference between channels at the same time. The method provided by the invention can effectively improve error code performance of the system and the capacity of the system.

The invention provides a self-adaptive bit distributing method and a self-adaptive bit distributing device in a cooperative multi-aerial system. The self-adaptive bit distributing method includes: extracting the receiving power of a data signal and an interference signal and time delay information of every channel according to channel estimation; according to the signal receiving power and the time delay information of every channel, respectively calculating an optimal feedback bit number distributed to data channels and every interfering channel on the premise of fixing a total feedback bit number, minimizing rate loss caused by non-ideal state of channel information; determining the size of a codebook according to the optimal feedback bit number, selecting and transmitting corresponding code-quantified channel state information from the codebook according to a minimum chordal distance criterion by the aid of ideal channel information, and receiving the code-quantified channel state information and generating a zero-forcing pre-coding matrix according to the same. The zero-forcing pre-coding operation is performed by the aid of the obtained non-ideal channel information via a base station, and interferences among multiple users in a local cell and among neighbor cells are restrained.

The invention provides a joint distribution method of limited feedback number of bits in a multi-point cooperation system. The method comprises the following steps that: a main base station and an assistant base station emit training sequences to a user, the user conducts channel estimation processing to obtain an estimated channel between the main base station and the assistant base station; the user feeds the power information of a receiving end back to the base station, and the main base station calculates a bit distribution scheme according to the information; the main base station feeds the bit distribution result back to each user; the user quantizes the channel information obtained in channel estimation according to the distributed feedback number of bits, and feeds numeral sequence back to the main base station; the main base and the assistant base station perform zero-forcing pre-coding matrix calculation according to the feedback channel status information; and the main base station and the assistant base station perform linear preprocessing to the user data and send the user data to the user. According to the joint distribution method of limited feedback number of bits in the multi-point cooperation system, a feedback bit joint distribution method is adopted to distribute feedback number of bits of the system to each channel of each user in a self-adaptive manner, and the cell throughout rate and the system total data rate are improved.

The invention discloses a pilot pollution-eliminated double-layer pre-coding design method in a massive MIMO (Multiple Input Multiple Output) system, and belongs to the technical field of wireless communication. The specific design process is as follows: when the system works in a TDD (Time Division Duplex) mode, sending a pilot sequence to a base station by a user for estimation of an uplink channel, and obtaining downlink channel estimation based on channel reciprocity by the base station; then designing an outer-layer pre-coding matrix based on a zero-forcing pre-coding idea at the base station end so as to suppress inter-user interference in a cell; and finally regarding a channel and the outer-layer pre-coding matrix as an integer to serve as an equivalent channel, and further designing an inner-layer pre-coding matrix based on a minimum mean square error criterion to suppress interference caused by pilot pollution in the system. According to the pilot pollution-eliminated double-layer pre-coding design method in the massive MIMO system, the pre-coding matrix is designed in combination with the pilot pollution elimination, and the problem of inherent pilot pollution existing in the massive MIMO system is solved.

The invention discloses a hybrid precoding energy efficiency optimization method of a millimeter wave MIMO-OFDM communication system. The hybrid precoding energy efficiency optimization method comprises the following steps: acquiring the maximum transmitting power of a millimeter wave MIMO-OFDM communication system base station and a channel matrix corresponding to each subcarrier; on the basis ofthe maximum transmitting power and each channel matrix, solving to obtain a power distribution value corresponding to each data stream under each subcarrier by taking the optimal energy efficiency ofthe base station as a target to form a subcarrier power distribution scheme; and obtaining a digital precoding matrix of each subcarrier and an analog precoding matrix suitable for all subcarriers based on the subcarrier power distribution scheme and the optimal energy efficiency target. According to the method, under the condition that the transmitting power of the base station is limited, a power distribution scheme and a hybrid precoding scheme which enable the energy efficiency to be optimal are provided. The combined design problem of hybrid precoding under broadband millimeter waves issolved, the energy efficiency is improved to the maximum extent, and compared with an existing all-digital zero-forcing precoding scheme, the energy efficiency of a millimeter wave MIMO-OFDM communication system is effectively improved while the network capacity performance is considered.

The invention belongs to the technical field of wireless communication, and relates to a phase noise suppression method for a large-scale MIMO orthogonal frequency division multiplexing system. According to the invention, multi-user communication is realized based on zero-forcing precoding; firstly, a training OFDM symbol is used for roughly estimating a composite channel, combining a physical channel and a zero-forcing precoding weight influence, of each user; then, an iterative algorithm is provided for information transmission OFDM symbols to jointly estimate data sequences and phase noiseand refine estimation of a composite channel, so that adverse effects of the phase noise in a large-scale MIMO orthogonal frequency division multiplexing system are effectively inhibited.

The invention discloses an anti-interval-interference base station downlink pre-coding method for a multi-cell MIMO (Multiple-Input Multiple-Output) system. The method comprises the following implementation steps of: 1, positioning a cell user by using a GPS (Global Positioning System) and judging whether the cell user is a central user or an edge user; 2, if the cell user is a central user, estimating channel state information (CSI) and feeding the CSI back to a base station; 3, if the cell user is an edge user, estimating CSI relative to a local cell base station and an interference base station, and feeding back the CSI to the local cell base station; 4, transmitting the CSI of the edge user between the base stations; and 5, computing a pre-coding matrix of the user with a zero-forcingpre-coding method on the base station with cell interference. According to the method, the data exchange amount between the base stations can be reduced, the accuracy of the CSI can be ensured, and realization of cell synchronization is facilitated; and the method can be applied to a fourth generation mobile communication system.

The invention discloses a multi-user precoding method in a coordinated multi-point system and mainly solves the problems of large average feedback cost and average return cost in the prior art. The multi-user precoding method comprises the following implementing steps that: a random vector is utilized to carry out quantization and generate a codebook and the codebook is prestored at user sides and a base station side; each user obtains a downlink channel vector of the user by channel estimation and calculates a single-link channel direction; each user selects a codeword serial number of the single-link channel direction and a corresponding channel quality indication according to the minimum distance criterion; each user compares the channel quality indication of the user with a preset threshold value to obtain a downlink feedback index vector of the user; a base station carries out packet scheduling on the users according to the feedback index vectors to obtain a final set of the users to be served; and the base station reconstructs a downlink channel matrix of the set of the users to implement the zero-forcing precoding of a transmitting terminal. According to the invention, the selective limiting feedback and the packet scheduling are combined, the average feedback cost and the average return cost of the system are greatly reduced and the multi-user precoding method can be used for the coordinated multi-point system with low cost.

The invention discloses a correlation rotation precoding method applied to a GFDM communication system. The problem of relatively low symbol error rate transmission performance of a generalized frequency division multiplexing GFDM communication system in the prior art is mainly solved. The related rotation precoding method comprises the following specific steps: (1) constructing an autocorrelation matrix; (2) constructing a zero forcing precoding matrix; (3) constructing a correlation rotation matrix; (4) eliminating a multiplicative channel fading factor; (5) constructing a correlation rotation precoding matrix; (6) precoding; and (7) transmitting a to-be-transmitted symbol. The correlation rotation precoding method disclosed by the invention has the advantages of high symbol error rate performance, adverse effects caused by self-interference and multi-path channel interference can be simultaneously eliminated, the interference is utilized to improve the symbol error rate transmission performance of the generalized frequency division multiplexing GFDM communication system, meanwhile the precoding processing method of signals is simple and feasible, and the signal transmission requirements of users in a real environment can be satisfied in a multi-path channel scene.

The invention discloses an inter-cluster interference elimination method based on airspace fine intensity high fractional beams for mainly solving the problem of poor quality of service of cell edge users resulting from the ARSs overlapping phenomenon and the path loss in the prior art. The inter-cluster interference elimination method comprises the following steps: 1) selecting a collaboration area, and calculating a space correlation matrix; 2) calculating a first stage pre-beam forming matrix according to the space correlation matrix so as to calculate an equivalent channel dimension; 3) calculating an optimal spatial degree of freedom; 4) comparing the total degree of freedom with the maximum equivalent channel dimension, judging whether user clusters are suitable for interference alignment, if so, calculating a second stage interference alignment encoding and decoding matrix, and otherwise, calculating a second stage zero-forcing pre-encoding matrix; and 5) calculating a two-stagepre-encoding matrix in conjunction with the first stage encoding and the second stage encoding. According to the inter-cluster interference elimination method, the interference in the edge clusters is eliminated by alignment interference, the interference in central clusters is eliminated by zero-forcing pre-encoding, so that the throughput of the system is effectively improved, and the inter-cluster interference elimination method can be used for large-scale MIMO cellular networks.

The invention discloses a downlink rateless code degree distribution and pre-coding combined optimization method for a cloud access network. For a downlink multi-user access scene of the cloud accessnetwork, we propose a pre-coding matrix and rateless code output degree distribution combined optimized method under the limit of the single-antenna peak power at an RRU (Remote Radio Unit) with the help of zero-forcing pre-coding idea in a baseband processing unit pool. Through the combined optimization of the rateless code degree distribution and pre-coding in a downlink multi-user scene of thecloud access network, the method can improve the total throughput capacity of a system.

The invention discloses a partial zero-forcing precoding method in a multi-cell MISO system. The method comprises the following steps: each base station uses its own spatial DoFs to perform zero-forcing precoding on users to be dispatched on the same frequency in the corresponding cell of the base station, wherein the sum of the number of subscribers K and c to be scheduled on the same frequency in the cell i corresponding to the base station i is less than or equal to the number of spatial DoFs of the base station i; c is the number of neighboring area users selected by the base station i forICI cancellation; 0<c <N/2; and N is the number of antennas of the base station i. c neighboring area users are selected according to the rule that c neighboring area users with the strongest averageICI caused by the base station i or closest to the base station I are selected. The invention can eliminate the IUI of each user to other users of the cell and the ICI of a part of users of the neighboring cell.

The invention discloses an intensive small cellular network user grouping and self-adaptive interference suppression method. The intensive small cellular network user grouping and self-adaptive interference suppression method comprises the steps that: firstly, a central processing unit groups users by utilizing large-scale fading channel information of each user, the users in the same group use the same pilot frequency, and the users of different groups use different orthogonal pilot frequencies; secondly, each small cellular base station determines adjacent intergroup interference users by utilizing the large-scale fading channel information of the users, and estimates channel vectors of the adjacent users by utilizing received uplink pilot frequency; if intergroup interference users do not exist, an uplink can adopt maximum ratio combination (MRC) reception and a downlink can adopt maximum ratio transmission (MRT) precoding; and if the intergroup interference users exist, the uplink can adopt zero-forcing reception and the downlink can adopt zero-forcing precoding transmission, so as to eliminate intergroup interference. The intensive small cellular network user grouping and self-adaptive interference suppression method can reduce pilot frequency pollution and reduce system pilot frequency overhead by adopting the simple user grouping method; moreover, the small cellular base stations eliminate the intergroup interference in a self-adaptive manner, and can effectively improve the spectral efficiency of the system.

Provided is a method and a device for precoding in a wireless communication system. The method for precoding comprises the following steps: generating a first precoding matrix, W₁, for deciding the transmission power of one transmission antenna from a plurality of transmission antennas as the maximum power per antenna; generating a zero forcing (ZF) precoding matrix, T_i, which does not influence the transmission antenna having the power which is decided as the maximum power per antenna, based on the (i−1)^th precoding matrix W_i−1 (i=2,3, . . . ); determining a constant which has the transmission power of one transmission antenna from the rest of the transmission antennas, which do not have the transmission power as the maximum power per antenna, based on the T_i; and generating the

The invention provides a zero-forcing precoding frame time slot anti-collision method for an RFID system and proposes a parallel anti-collision algorithm based on combination of zero-forcing precodingand a frame time slot ALOHA algorithm. Through the precoding technology, encoding is performed in advance before label transmission, so that error codes or collisions in a transmission and receivingprocess can be reduced. A simulation result indicates that when the total label number is 1000, the throughput rate is around 0.7 and is increased by about 83% compared with that of an ISE-BS algorithm, by about 20% compared with that of a DGBT algorithm, and by about 300% compared with that of an FSA algorithm. According to the invention, the throughput rate and the stability are improved and good application values are achieved in fields requiring quick identification of a large amount of labels.