424 results about "Interference alignment" patented technology

A communication system may include a serving base station and neighboring base stations. Each of the serving base station and the neighboring base stations may have a corresponding user group. Terminals belonging to a particular user group may feed back information associated with interference channels, and reasonably generate a precoding matrix. Through this, it is possible to perform an accurate interference alignment and to enhance a throughput. In this instance, terminals belonging to the other user groups may feed back information associated with a throughput, and a corresponding base station may perform the interference alignment using a user selection resulting in decreased overhead.

System and method embodiments are provided for interference alignment in a wireless local area network (LAN) with an overlapping basic service set (OBSS). In an embodiment, a method includes instructing a first access point (AP) in the wireless LAN to broadcast a null data packet (NDP) sounding packet to a plurality of stations when no other AP is broadcasting, wherein the NDP sounding packet comprises a plurality of long training field (LTFs), and wherein a total number of LTFs is equal to a total number of transmission streams, receiving channel beamforming (BF) information and a signal plus interference to noise ratio (SINR) from each of the stations, wherein each of the stations computes the channel BF information and the SINR from sounding packets received from each of the APs in the wireless LAN, and determining a transmission schedule according to the SINRs and the channel BF information.

A communication device and a mobile station to perform interference alignment, and an interference alignment method are provided. Interference alignment may be performed to enable an interference signal, received in a mobile station, to be removed using channel information fed back from the mobile station.

A central base station for interference management in a distributed antenna system comprises a processor; a memory; and a frequency partition module configured to divide the remote radio heads into clusters and allocate a frequency band to each cluster. Multiple clusters use the same frequency band and groups of clusters are formed. A joint scheduler is configured, for each group, to activate at most two clusters at any given time and deactivate remaining clusters in the group, one of the at most two activated clusters being a serving cluster of the group, and to associate one or more users with the serving cluster in the group. An interference alignment module is configured to apply downlink interference alignment between the at most two activated clusters in each group to align transmit directions of all interferences between the at most two activated clusters.

The invention discloses a characteristic sub-channel-based interference alignment pre-coding matrix optimizing method. The method is characterized by comprising the following steps of: on the basis of interference alignment, performing singular value decomposition on a channel matrix from a base station of the local cell to a user of the local cell to acquire the best group of characteristic sub-channels, selecting a group of pre-coding vectors with the maximum weighted inner product with the best group of characteristic sub-channels from a pre-coding vector set acquired according to the interference alignment condition, and arranging the pre-coding vectors side by side to form the pre-coding matrix, wherein weighting factors are singular values respectively corresponding to the group of singular vectors. The method makes full use of the channel information from the base station to the user of the local cell while taking the alignment with interference of other cells into full consideration, allows a signal sent by the base station to the user to experience the best group of characteristic sub-channels, enhances intensity of the signal received by the user end and improves the system throughput.

A communication method of a base station and a terminal based on interference alignment in a multi-cell multi-user multiple-input multiple-output (MIMO) interference channel and a method and apparatus of communication using interference alignment and block successive interference pre-cancellation in a multi-user MIMO interference channel. The base station may determine a precoding matrix to maximize a signal to interference and noise ratio (SINR) and a signal to leakage and noise ratio (SLNR) in the interference channel, and a terminal communicating with the base station may determine a decoding matrix to align interference. The transmitter including a multicell interference channel may calculate a rotation matrix for interference alignment, identify effective symbol vectors using the rotation matrix, and generate a transmit signal of a target transmitter to pre-cancel interference corresponding to a transmit signal of a neighboring transmitter.

Provided is an interference aligning method and apparatus that does not perform full feed-forwarding in a hierarchical cell communication. A macro base station may generate respective transmission beamforming vectors of macro terminals to null interference channels to pico terminals and to remove interference among the macro terminals. The effective interference channels are based on reception beamforming vectors of the pico terminals. The macro base station may transmit, to a macro terminal, a feed-forward indicator (FFI) indicating a method of transmitting information associated with a reception beamforming vector of the macro terminal. The macro terminal may obtain information associated with the reception beamforming vector based on the FFI.

An interference alignment system for communication structures that includes a single cell channel comprising an access point node, and a full bipartite interference channel (FBIC) configuration of a plurality of receiving nodes and a plurality of transmitting nodes. Each receiving node sees an interfering signal from all transmitting nodes. The access point node of the single cell channel provides a single node having downlink channels to all receiving nodes in the FBIC, and all of the uplink channels from the FBIC are to the single access point node to the single cell channel.

A method, system, and computer program product for minimizing intra-cell and inter-cell interference in a multi-cell full duplex communication system in a wireless network. The method includes selecting, by a clint selector, a plurality of clients, wherein the plurality of clients includes a plurality of uplink clients configured to transmit signals and a plurality of downlink clients configured to receive signals over a plurality of data streams in each cell of the multi-cell full duplex communication system, and performing, by a spatial interference aligner, spatial interference alignment on interfering data streams to align the interfering data streams of uplink clients towards downlink clients in its own cell and downlink clients in a neighboring cell.

A method and system are disclosed herein for power allocation and/or clustering in a wireless communication system that uses blind interference alignment. In one embodiment, the system comprises a plurality of receivers, where each receiver in the plurality has a multi-mode antenna with a single radio frequency (RF) chain that is operable in a plurality of antenna modes, and wherein each receiver shifts between the plurality of antenna modes in a predetermined manner. The system also includes a plurality of base stations to perform cluster-based transmission, each base station in the plurality of base stations having one or more transmitters having a transmit antenna and being operable to communicate with one or more of receivers in the plurality of receivers using a blind interference alignment (BIA) scheme, and wherein the plurality of base stations are grouped in different clusters at different times according to cluster patterns.

A mobile station and a network control apparatus are provided. The network control apparatus may generate beamforming information, associated with an interference alignment of a plurality of mobile stations, and transmit the beamforming information to a plurality of base stations. The mobile station may receive a signal from the plurality of base stations based on the beamforming information.

This invention provides a method for exploiting precoder optimization gains and multi-user diversity gains with interference alignment in general MIMO wireless networks including multiple users. Specifically, two embodiments exploit either a gradient-based search or iteratively orthogonalizing inference. The method can achieve near-optimal performance at a low complexity. Furthermore, a scheduling criterion is provided for wireless networks comprised of a large number of mobile stations in each cell. The criterion can be done independently in each cell to significantly reduce information exchanged between base stations in different cells compared to the methods that perform joint scheduling over all cells. The two embodiments can be utilized in a spectrally efficient communications network equipped with relaying nodes.

The invention discloses a safe transmission method in an MIMO Y eavesdropping network based on real interference alignment. According to the method, through utilization of a real interference alignment technology and an artificial noise technology, through construction of useful signal precoding matrixes and interference suppression matrixes, inter-user interference signals at legal user positions are located in null spaces of receiving suppression matrixes; and noise signals are completely eliminated through linear combination. Moreover, through construction of a noise signal coding matrix at a relay position, the noise signals are completely aligned to receiving signal spaces of eavesdropping users, so the eavesdropping users cannot eavesdrop the signals and the whole multi-user eavesdropping network can obtain multiple safe communication channels.

A method and apparatus is disclosed herein for scheduling over ODFM via interference alignment based on multipath intensity profile information. In one embodiment, the method comprises grouping user terminals into groups based on their multipath intensity profiles, where at least one of the groups has two or more terminals; scheduling user terminal groups for MU-MIMO transmission; allocating OFDM resources to the user terminal groups for MIMO transmission; assigning MU-MIMO transmission codes to the user terminal groups; and performing MU-MIMO transmission of the user terminal groups using assigned MU-MIMO transmission codes.

The invention discloses a base station antenna selecting method based on interference alignment in a multi-cell system, and mainly solves the problems that an existing multi-antenna interference alignment technology is relatively high in system hardware cost, and the base station antenna selecting method based on interference alignment can only be used in a network comprising 3 cells. The method comprises the following implementation steps of: estimating state information of channels from various base stations to users in the resident cells; initiating base station antenna selection schemes of the various cells; along a system and capacity increase optimizing direction, under the condition that other base station antenna selection schemes are unchanged, determining the optimal base station selection schemes of the various cells in sequence by using partial iterative interference alignment; and performing multi-cell interference coordination by adopting traditional iterative interference alignment. The base station antenna selecting method is applicable to an LTE (Long Term Evolution) network oriented to commercial use with a plurality of cells, is low in computation complexity, can reduce the system hardware cost, and realizes compromise between system and capacity and computation complexity.

The invention discloses a design method for two-level precodes of a cognitive MIMO communication system and relates to the technical field of the cognitive MIMO communication systems. In the MIMO communication system, a cognitive user adopts an opportunistic access mode to use space sub-channels of a main user, and interference, generated on the main user, of the cognitive user is reduced through an interference alignment method; interference alignment is achieved through precode designing of all transmitting ends of the cognitive user. According to the transmission performance of the main user, a precode matrix can be designed on the basis of transmission channel matrix singular value decomposition, and power distribution of the transmitting ends is achieved by the utilization of a water-filling method; the design for the two-level precodes is performed on the transmitting ends of the cognitive user, the first level precode is used for aligning the interference generated, on the main user, of the cognitive user to the space sub-channels available for the main user, and the second level precode is used for promoting the transmission performance of the cognitive user. By the adoption of the design method for the two-level precodes, under the condition that the interference, on the main user, of the cognitive user is reduced, the transmission performance of the cognitive user is guaranteed.

The invention provides a cognitive radio user space division multiplexing method based on interference alignment. According to the cognitive radio user space division multiplexing method based on interference alignment, in the situation that a primary system has certain tolerance against external interference, a cognitive system obtains the tolerance of the primary system against external interference, and the tolerance serves as the reference for the fact that the cognitive system selects cognitive radio users to conduct data transmission. The cognitive system conducts interference elimination on the selected cognitive radio users according to the interference alignment method. When the cognitive radio users are selected, the sum of the maximum possible interference values leaked to the primary system by the cognitive radio users and the tolerance of the primary system against the interference are compared through the Rayleigh quotient characteristics of a channel matrix, and therefore the effect that the interference in the primary system from the selected cognitive radio users is controllable is achieved. By the adoption of the cognitive radio user space division multiplexing method based on interference alignment, the interference alignment technology is widely applied to the cognitive radio network, and the accessibility and the rate of a cognitive radio system are improved.

The invention discloses a cooperative multi-point transmission method based on interference alignment and interference neutralization. The cooperative multi-point transmission method based on interference alignment and interference neutralization only uses base station side cooperation, eliminates residual interference and recovers expectation data through the precode vector design based on interference alignment and interference neutralization and an orthogonal projection filtering wave receiving technology adopted at a user side. Compared with the prior art, concurrent transmission of multiple paths of data is achieved only by using base station side cooperation and through combined design of precode emission and filtering wave receiving. At an emission end, two paths of interference signals carrying identical data information are aligned to opposite directions of the same sub-space through an IN, and interference signals carrying different data information are aligned to the same sub-space through an IA. A receiving end adopts orthogonal projection filtering waves to finish elimination of residual interference and recovery of the expectation data. In addition, the cooperative multi-point transmission method based on interference alignment and interference neutralization uses interaction of partial data, does not need user side cooperation, can make full use of space reuse capacity provided by multiple antenna systems, and achieves improvement in the handling performance of the systems.

The invention provides a topological interference alignment method of an MIMO interference broadcast channel for solving the technical problem that the topological interference alignment of generalized MIMO cannot be realized in the prior art. The method comprises the following steps: setting the system; constructing a partial connection model of MIMO IBC, and then converting the same into the partial connection model of MIMO IC through virtual base station expansion; solving a precoding matrix and a decoding matrix of an MIMO IC system satisfying a topological interference condition; designing an MIMO IBC precoding matrix and a decoding matrix, and eliminating inter-cell interference through proper signal processing technology; and designing a precoding matrix of a base station to eliminate intra-cell interference. By adoption of the topological interference alignment method provided by the invention, the topological interference alignment of generalized MIMO IBC can be realized, and a lower limit of a degree of freedom that can be reached by the MIMO IBC system with given topological information can be analyzed.

Aspects of this disclosure provide techniques for computing Vandermonde-subspace frequency division multiplexing (VFDM) precoders for secondary network transmissions that mitigate interference between secondary communication signals, while avoiding interference with the primary system altogether. A precoder for a secondary user (SU) is computed on accordance with a nullspace induced by cyclic prefixes communicated over a primary data channel, a primary interference channel between a second user (SU) and the primary receiver, and a secondary interference channel between the SU and a neighboring SBS. The precoder provides both frequency domain precoding and spatial domain precoding on secondary transmission signals communicated from the SU.

The invention discloses a downlink interference elimination method based on scheduling and interference alignment in a heterogeneous cellular network. The downlink interference elimination method mainly aims to solve the problem of downlink interference in the heterogeneous cellular network, and includes the steps that step 1, channel state information of each base station a user is measured by the user and fed back to each base station; step 2, downlink transmission link scheduling is carried out by each base station according to the channel state information; step 3, a sending beam forming matrix of a base station to be scheduled is constructed by a macro base station and sent to each base station through a backhaul; step 4, data are sent to the user by the base station to be scheduled through the constructed sending beam forming matrix; step 5, the beam forming matrix is received by the user, interference is eliminated, and the data are received. According to the downlink interference elimination method, the link which can achieve the maximum downlink throughout capacity is scheduled for transmission according to interference alignment feasible conditions, mutual interference between links to be scheduled is avoided through the interference alignment, network throughout capacity is improved, and the downlink interference elimination method can be used for heterogeneous cellular network communication.

A method for a partial interference alignment in a multi-antenna communication system includes, checking the number of access points (APs) operating at the same channel or adjacent channel; and calculating LIPs (Leakage Interference Power) that the respective APs have an effect on each base-station (STA). Further, the method includes choosing the upper three AP-STA pairs having the highest LIP in order as a candidate group for interference alignment; and performing a partial interference alignment on the candidate group for interference alignment.

A system and method for realizing virtual interference alignment. The system comprises a retrieving module, a determination module and a precoding module. The retrieving module retrieves source data. The determination module receives shared data and transmission information. The shared data and transmission information are generated from a shared signal received from one or more participating communication systems associated with a first virtual transmitting group. The precoding module calculates a precoding vector describing one or more requirements of interference alignment based at least in part on the transmission information. The precoding module generates a first transmission signal based at least in part on the precoding vector, the source data and the shared data.

The invention discloses an interference elimination method based on clustering interference alignment under a Femtocell network. A wireless communication network includes a macro base station, L macro users, K Femtocell base stations and K Femtocell users. One Femtocell base station and one Femtocell user form a Femtocell base station user pair. Each of the macro users and Femtocell users is provided with Mt transmitting antennae. The macro base station is provided with No receiving antennae. Each Femtocell base station is provided with Nf receiving antennae. Clustering is targeted at all Femtocell base station user pairs. The method includes the following steps: under the Femtocell network, firstly clustering the Femtocell base station users and then considering cross-layer interferences and at last using an interference alignment technology to eliminate interferences between the macro users and each cluster and thus effective comprise between complexity, link expenditure and system performance is realized. The method makes full use of frequency spectrum resources and realizes better system performance with lower complexity.

The invention discloses a self-reference interference alignment system for photoetching equipment. The system comprises a laser light source module, an optical module, a signal acquisition module and a processing module, wherein the laser light source module is used for providing illumination beams; the optical module is used for marking the illumination beams to form a diffraction optical signal; the signal acquisition module is used for processing the optical signal to acquire a light intensity signal; the processing module is used for processing the light intensity signal to acquire an alignment position by combining position data of a workpiece table; the optical module comprises a first optical channel and a second optical channel; an optical signal in the second optical channel is processed to be used for eliminating optical noises in the first optical channel.

According to one aspect of the present invention, the present invention provides a method for allowing a base station, which receives signals from one or more terminals, to align receiving signals and interference signals in a wireless access system. Said method comprises the steps of: receiving the receiving signals and the interference signals, wherein said receiving signals are signals which are received from terminals that belong to a serving cell of said base station, and said interference signals are signals which are received from terminals that belong to neighbor cells of said base station; dividing a signal space for receiving said receiving signals and said interference signals into one or more signal spaces of size N; and arranging K receiving signals of said receiving signals in each of said divided signal spaces, wherein said K receiving signals arranged in each of said divided signal spaces are orthogonal to each other.