32 results about "Multiuser detector" patented technology

A multi-user decoder is disclosed in which interfering users are assigned to levels of a decoding tree constructed in the decoder dependent on the power levels of the user's received signals and for each symbol interval. By building the decoding tree in this manner for each symbol interval, a reduced complexity search is more likely to include paths and nodes in the tree containing the correct value for the channel symbols.

A multiple access processing system for a plurality of users employing a multiuser detector processing partial blocks of data within a window. The multiuser detector processes the data for all users within a processing window and is interrupted at successive frame boundaries. Once an entire block is processed by the MUD, the blocks for that user are decoded and the processing continues.

A multiuser detector system with correlation based pruning including a parameter estimation module adapted to receive complex signals, and to produce estimated signature waveforms for each of K co-channel interfering signals. Pre-processing the estimated signature waveforms using an S-matrix module and producing a more valid set of hypotheses, wherein the S-matrix module uses apriori knowledge of an unnormalized cross correlation matrix, and processing the more valid set of hypotheses for pruning with an M-algorithm in a multiuser detector module. An improvement to the M-algorithm in which the interference structure based on the signal correlation matrix used during the optimization process aids in selecting a better subset of hypotheses to test. This approach has the benefit of reducing computational complexity and improving performance over the existing M-algorithm.

A multiuser detector method and receiver that detects and decodes synchronous or asynchronous CDMA subchannels having different spreading factors with reduced computational complexity. The multiuser receiver is compatible with ZF-BLE, MMSE, decorrelating detectors and the like using Cholesky decomposition to minimize numeric operations. The receiver and method arranges the columns of system transmission response matrices representing the response characteristics of individual users into a total system transmission response matrix which represents a plurality of matched-filter responses for a given block of received data. The invention when used in conjunction with Cholesky decomposition reduces the number of required mathematic operations prior to parallel matched filtering.

A Tree-structured multicarrier multiple access communication system in a multiple access environment having a number of interfering signals. In one embodiment an environment estimator estimates and tracks the number of interfering signals of the environment. A code selector determines an optimal spreading code represented by the environment, and identifies an actual spreading code that is closest to the optimal spreading code. A signal transmitter can then be used to transmit a multicarrier multiple access signals in accordance with the actual spreading code identified. On the receiver side, a multiuser detector (MUD) module performs tree structured multiuser detection signal processing, and produces a bit stream for each interfering signal.

Performing approximate diagonalization of a correlation metric by user permutation to improve Multiuser Detector (MUD) processing. The system reorders the entries in the S-Matrix in order to move the bit decisions closer together in the decision tree. In one embodiment the reordering is a sequential pairwise correlation.

A space-time multiuser detector simultaneously reduces multiple access interference (MAI) and multipath channel distortion (MCD) that are disadvantages of mobile communication systems. The space-time multiuser detector includes a plurality of receiving antennas; a channel estimator which estimates signals received via the receiving antennas; a space-time diversity decoder which performs space-time decoding with respect to the signals provided from the channel estimator and performs diversity combination; a signal aligner which aligns the signals provided from the space-time diversity decoder; and a successive interference cancellation detector which generates an interference signal from the signals that are provided from the signal aligner one by one in sequence, and removes the interference signal from the received original signals.

An FDM-CPM multi-user detector (30) jointly detects the received symbols for all users by determining from the received multi-user signal an a-posteriori probability mass function (pmf) of a time-sequence of states and transmitted symbols of all users, by iterative message passing corresponding to a specific factorisation of the pmf. The factorisation involves a combined variable representing possible transmitted symbols and CPM states of each user for each symbol time interval, so as to make the iterative process convergent. Non exponential complexity is enabled by disregarding multiple access interference (MAI) from at least some of the other users. Applications can include hubs for satellite communication ground stations.

The efficient iterative coding multi-user detection method used in the OFDM system belongs to the technical field of coding multi-user detection, and is characterized in that it is a method that uses interleaving patterns to distinguish users and iterates between joint multi-user demodulation and single-user decoding detection method. At the same time, it proposes a fast method for calculating the maximum a posteriori probability of coded bits for multi-user demodulators, in which a maximum a posteriori probability of coded bits is constructed using the equivalent user modulation symbol vector as an argument to calculate the maximum The measurement function of the posterior probability, using the characteristics of this function, can avoid a large amount of computation for calculating the function values ​​of all modulation symbol vectors. Finally, according to the function values ​​of all modulation symbol vectors, the maximum a posteriori probability of each user coded bit is calculated. It has the advantage of greatly reducing the amount of calculation in the multi-user demodulator while improving the spectrum efficiency and user capacity, which is convenient for practical use.

The method of realizing multiuser detector in ultrashort pulse light CDMA system adopts photoelectronic mixed detection mode and has parallel interference eliminating multistage structure. Traditional single-user detector is used as the first stage of detector, and subsequent stages has re-constituted multiaddress interference on the basis of the preceding stage detection as the basis of re-judging. The present invention has calculation complexity related linearly with the number of users and the number of the stages in the system. Therefore, the present invention can inhibit the influence of multiaddress interference on system performance and greatly improve the error code rate characteristic of great capacity system while controlling the calculation complexity.

The invention relates to a design method of a robust multi-user detector, which solves the technical problem of high bit error rate of the traditional multi-user detector under the impact noise channel environment, by initializing algorithm parameters; using the opposite learning method to initialize the parent population, and determining Three wolves in the parent population; use the improved gray wolf algorithm position update equation to update the parent population, and sort the population individuals according to the fitness value from large to small; use the parent population to generate offspring cross variants, when the child When the fitness value of the first-generation mutant is better than that of the parent population, the evolutionary direction of the offspring mutant individual and the information on the probability of successful cross-mutation are used for position information difference, and the new evolutionary direction information is obtained and saved, and the position of the three wolves is updated at the same time; Using Huber's theory and using the non-fast increasing function of the residual error to design the technical scheme of the multiuser detector under the impulsive noise channel, this problem is better solved, and it can be used in the design of the multiuser detector.

The embodiment of the invention provides a signal detection method and device applied to a non-orthogonal multiple access system. The method and device are applied to a multi-user detector. The method comprises the following steps: according to an evaluation probability predicted value on a log domain, currently saved by another user node connected with a resource block node to be updated currently, determining an evaluation probability predicted value on the log domain of the resource block node to be updated currently, transferred to the user node, and sending the value to the user node so as to be saved; according to the evaluation probability predicted value on the log domain, currently saved by the user node and a prior probability value on the log domain of the user node, determining an evaluation probability predicted value on the log domain, transferred to a next resource block node connected with the user node, of the user node; and sending the value to the next resource block node connected with the user node so as to be saved. By applying the embodiment of the invention, the convergence rate of an MPA algorithm can be effectively increased, and the processing delay of the multi-user detector can be reduced.

A method for the simultaneous reception of data from multiple sources having different spreading factors. A plurality of transmission response matrices are generated and grouped together for equal spreading factors. A plurality of spreading factor group matrices are assembled. A base matrix is formed based upon the spreading factor group matrix having a lowest spreading factor. An additional spreading factor group matrix is selected for consideration. Column placement reference index for the base matrix is derived. A reference location for the base matrix is derived. A column set from the selected spreading factor group matrix is derived. The column set is inserted into the base matrix. A total transmission response matrix is assembled.