34 results about "Chordal distance" patented technology

A method for transmitting and receiving uplink signals using an optimized rank 3 codebook is disclosed. The optimized rank 3 codebook includes 12 precoding matrix groups, which are consisted of 6 Tx antenna power balanced precoding matrix groups and 6 layer power balanced precoding matrix groups. Preferably, the optimized 4Tx rank 3 codebook has 20 precoding matrix, two precoding matrixes are selected from each the 6 Tx antenna power balanced precoding matrix groups, considering chordal distance and the number of precoding matrix. And then 8 precoding matrices are selected from the layer balanced precoding matrix groups.

A non-destructive real-time continuous concrete carbonation depth testing method comprises the following steps: firstly making concrete test block with spherical concave, having drying process after test block curing, sealing all surfaces with the heated paraffin except a bottom surface, placing the test block in a carbonization box, taking the test block out at different days to test the carbonation depth thereof, having groove-catching process upon the segmental paraffin-sealed surface of the test blcok, injecting R alizarin yellow reagent, draining the reagent, after confirming the discolouring interface, selecting the testing points, measuring the chordal distance of each point of the four laterals, calculating the carbonation depth value for each point, taking the mean value as the testing value and drawing the relation curve between the carbonation time and the carbonation depth with the carbonation depths tested at different days to express the development rule of the concrete under the condition. The invention can test the carbonation depth continuously in real time with high precision, which is beneficial for the study of concrete durability.

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 relates to a user scheduling method and equipment in an MIMO (Multiple Input Multiple Output) wireless communication system. All user equipment select the respective channel vectors from a codebook according to the minimum chordal distance rule, the SINR (Signal to Interference Plus Noise Ratio) value of a channel between each user equipment and a base station of which the user equipment belongs, then the indexes and the SINR values of the channel vectors of all the user equipment are sent to network equipment, the network equipment selects the user equipment according to channel-related information fed back by all the user equipment to enable the channel response matrix of each selected user equipment and the combined channel response matrix of other selected user equipment to meet the predetermined orthogonality condition, and the codebook reconstructs the corresponding pre-encodingmatrix in a centralized manner according to the respective codebook indexes of all the selected user equipment. The invention has the advantages that the channel response direction vectors of users are quantified by adopting the minimum chordal distance rule, and the users are scheduled by adopting the chordal distance, so that a good balance is stricken for reducing both the common-channel interference (CCI) and multi-user diversity gain.

The invention provides an interference alignment method in a heterogeneous cellular network. With the adoption of the interference alignment method in the heterogeneous cellular network provided by the invention, same frequency interference can be effectively inhibited in terms of interference overlapping, and accordingly, the performance of a user is improved. The interference alignment method overcomes the defect that in a conventional technique for coordinately processing inter-cell interference with a resource orthogonal division method, each user occupies a few channel resources; in order to solve the problem that influence of non-ideal CSI (customer satisfaction index) on the performance of a system is not taken into consideration in a conventional heterogeneous cellular network interference alignment technique, the interference alignment method performs interference alignment design in a limiting feedback system, takes influence of non-ideal CSI on the performance of the system into consideration, performs bit allocation at the aim of minimization of average speed loss and performs channel quantization under the principle of minimization of chordal distance.

The invention discloses a double-codebook multi-user multiple-input multiple-output (MU-MIMO) precoding method based on Schmidt orthonormalization, and belongs to the communication field. The precoding method includes the following steps: (1) constructing a codebook I according to the Grossmann space packing principle, then constructing a codebook II according to the Schmidt orthonormalization principle and considering the chordal distance between vectors, and storing the two codebooks together in a base station end and a mobile station, (2) carrying out channel estimation according to pilot signals sent by a base station, then going through precoding vectors in the codebook I, selecting out best matching code words, and sending indexes and corresponding signal interference plus noise ratio (SINR) values of the code words to the base station as feedback, (3) the base station ensuring a present precoding matrix in the codebook II according to the collected feedback information, and carrying out user scheduling on the basis. Through adoption of the method, an expanded space of the codebooks are enabled to be larger, moreover orthogonal property of the precoding matrix is guaranteed, and restraining capacity to color contribution index (CCI) is ensured. Meanwhile, the user scheduling scheme of the base station end enables the failure phenomenon of user matching not to exist.

A coordinated beamforming method and apparatus based on partial interference alignment, the method includes: selecting an optimal partial interference alignment mode from selectable partial interference alignment modes of terminals covered by base stations in a coordinating cluster of a coordinated multiple points transmission according to a chordal distance criterion; and transmitting, by the base stations, signals to the terminals by adopting the optimal partial interference alignment mode.

The invention provides a user selection algorithm for a heterogeneous network, and the algorithm comprises the steps: calculating the chordal distances of interference channel matrixes between a macro base station and all users in a cell; selecting a user which enables the directions of the interference channel matrixes to remain parallel, i.e., enabling the user with the minimum chordal distance between the interference channel matrixes to serve as a service user. According to the invention, the algorithm takes the chordal distances as direction measurement indexes for the channel matrixes, further takes a weighted value as a measurement index, enables the interference channel matrixes to remain parallel as much as possible through considering the characteristics of a multi-base-station cooperation system, and optimizes the interference between hierarchy-crossing cells between a macro honeycomb and a micro honeycomb, so as to achieve a purpose of enabling the interference with users of the cell from the macro cell to be minimum.

The invention discloses a downlink MU_COMP (Multi-User_Coordinated Multiple Point) scheduling algorithm based on an improved chordal distance, which comprises the following steps that S1, edge cell users detect the strength of a current interference signal and feed back current signal interference noise ratios, and an activated user set in a coordinated transmission mode is determined according to the signal interference noise ratios; S2, a candidate user set and a selected user set are established, wherein the candidate user set comprises users in the activated user set; one of the users with the maximum F norm in the candidate user set is added to the selected user set, and the channel capacity of the users in the selected user set is computed; S3, a chordal distance between each user channel matrix in the candidate user set and a combined channel matrix in the selected user set is computed; S4, the user with the maximum chordal distance between the user channel matrix and the combined channel matrix in the selected user set is selected; S5, whether the users in the selected user set reach an upper user limit is judged, if so, S2 is skipped to, and if not, S6 is skipped to; and S6, block diagonalization precoding matrixes are designed for the edge cell users in the selected user set respectively, and a coordination base station uses the block diagonalization precoding matrixes to perform combined precoding and sending on the edge cell users.

Disclosed is a multiple-input multiple-output (MIMO) system including a transmitting end and a receiving end, wherein the transmitting end includes: a hierarchical codebook in which at least one base codebook is designated as the upper matrix and a child codebook generated based on a chordal distance between respective codewords configuring the base codebook is designated as the lower matrix; a scheduler configured to receive channel state information from the receiving end and select precoding matrices from the hierarchical codebook based on the channel state information; and a precoder configured to apply the precoding matrices selected in the scheduler to data to be transmitted to the receiving end and transmit the selected precoding matrices through a plurality of antennas.

The invention relates to an optimization algorithm combining antenna selection with interference alignment in an MIMO (multiple input multiple output) system, and belongs to the technical field of wireless communication. The method mainly includes the steps: (1) initializing a maximum chordal distance to be zero, selecting N antennas from total transmitting antennas and listing all possible antenna subsets at a transmitting end; (2) calculating interference alignment pre-coding and an interference suppression matrix through minimum criteria of inner product norms according to the selected antenna subsets; (3) calculating the chordal distance between an interference subspace and an desired signal subspace; (4) storing the chordal distances of the selected antenna subsets, comparing the chordal distances with the initialized maximum chordal distance, and updating maximum chordal distance parameters according to comparison results. The interference alignment and antenna selection joint algorithm considers the problem of serious mutual interference between high complexity of a traditional antenna selection algorithm and a user, interference alignment processing interference superiorityis ensured, the strength of desired signals at a receiving end is maximum, and complexity of search for optimal antenna subsets is reduced.

The invention belongs to the technical field of wireless communication and discloses an opportunistic interference alignment method based on limited feedback in a wireless mobile communication system.According to the opportunistic interference alignment method based on the limited feedback in the wireless mobile communication system, precoding matrixes are designed for all users in a cell at a position of a base station; a user scheduling process of an uplink is finished at the position of the base station through adoption of a normalization minimum chordal distance clustering analysis method; scheduled user labels are fed back, and the users in the cell finish establishing the precoding matrixes; and a receiving zero-forcing matrix is designed at each receiving end, thereby finishing a zero-forcing process of a practical interference link. According to the method, through utilization of multiuser classification gain, a transmission rate of the system is clearly improved under the condition that feedback bits are limited and the limitation resulting from the limited feedback is reduced, so the relatively good transmission rate can be achieved under the condition of relatively fewfeedback bits.

The embodiment of the invention discloses a codebook searching method. The method comprises the following steps: searching for a first optimal pre-coding matrix from a pre-coding matrix set; determining an nth codebook searching subset according to an (n-1)th optimal pre-coding matrix and an nth chordal distance level, wherein the nth codebook searching subset is a subset of the pre-coding matrix set; and searching for an nth optimal pre-coding matrix from the nth codebook searching subset, wherein n is 2,...,m, and m is an integer being greater than or equal to 2. The embodiment of the invention also discloses a codebook searching device.

A method of assembling a ball bearing assembly includes the steps of forming a one-piece metallic ball bearing cage having an initial configuration with ball pockets and bridge portions (16) between the ball pockets, at least a portion of the bridge portions (16) having a predetermined chordal length. The bearing balls (52) are positioned within an annulus between inner and outer bearing rings (68, 70), the bearing balls (52) being separated by an average chordal distance less than said predetermined chordal length and then the ball bearing cage is inserted into the annulus such that circumferential movement of the bearing balls (52) allows the bridge portions (16) of the ball bearing cage to pass between adjacent bearing balls (52) as the bearing balls (52) sequentially enter the ball pockets.

Methods and apparatuses for hybrid beamforming are described. The described methods and apparatuses related to hybrid beamforming for single user multiple-input multiple-output (SU MIMO) communications and for multi-user multiple-input single-output (MU MISO) communications. The radio frequency (RF) precoder and baseband precoder are determined such that the hybrid precoder has a minimum or near minimum chordal distance from an optimal precoder. Feedback information enables the transmitter to select columns from a set of discrete Fourier transform (DFT) columns to form the RF precoder matrix.

The embodiment of the invention provides a precoding method and device and an electronic device. The method comprises the following steps: selecting an optimal code word of a current channel accordingto a Type I codebook scheme, calculating the chord distance between the optimal code word and the current channel, the chord distance being used as target chord distance, wherein the target chord distance represents the similarity of the optimal code word and the current channel on the vector; and if the target chord distance is not greater than the preset chord distance, updating the optimal code word according to a Type II codebook scheme; and sending precoding information carrying the index of the updated optimal code word to the base station end, and the base station end carrying out precoding according to the updated index of the optimal code word. After the optimal codeword is determined according to the Type I type codebook scheme, the optimal codeword can be updated according to the Type II type codebook scheme under the condition that the similarity between the optimal codeword and the current channel on the vector and the preset chord distance are not greater than the presetchord distance, so that the dynamic adjustment of the codebook scheme is realized.

The invention provides a multi-base-station cooperative system parameter transmission optimization method based on singular value decomposition (SVD). The method comprises that a cooperative transmission multiplex flux of each cooperative base station is initialized to be a rank of a united channel matrix of each cooperative base station; the united channel matrix of each cooperative base station is discomposed according to SVD and a matrix V is obtained; a precoding matrix of each cooperative base station is determined according to the chordal distance minimum principle and classification optimization of the matrix V; an equivalent channel matrix is obtained according to the precoding matrix of each cooperative base station, and a signal to noise ratio of each multiplex flux is calculated; whether the signal to noise ratio of each multiplex flux satisfies the requirements of a system is judged, if the signal to noise ratio of each multiplex flux satisfies the requirements, a coding modulation format of each multiplex flux is determined according to the signal to noise ratio of each multiplex flux and the multiple flux transmitted by each cooperative base station, the coding modulation format of each multiplex flux and the precoding matrix of each cooperative base station are fed back to a user; and otherwise, the steps above are repeated after each cooperative transmission multiplex flux minus one. According to the multi-base-station cooperative system parameter transmission optimization method based on SVD, transmission parameter selective calculated amount is reduced greatly and high throughput of a system is obtained.

A method for transmitting and receiving uplink signals using an optimized rank 3 codebook is disclosed. The optimized rank 3 codebook includes 6 precoding matrix groups, each of which has 1 variable having an amplitude of 1. Preferably, the optimized 4Tx rank 3 codebook has 12 precoding matrix, two precoding matrixes are selected from each the above 6 precoding matrix groups considering chordal distance and the number of precoding matrix.