557 results about "Channel models" patented technology

A method and apparatus for segmenting text is provided that identifies a sequence of entity types from a sequence of characters and thereby identifies a segmentation for the sequence of characters. Under the invention, the sequence of entity types is identified using probabilistic models that describe the likelihood of a sequence of entities and the likelihood of sequences of characters given particular entities. Under one aspect of the invention, organization name entities are identified from a first sequence of identified entities to form a final sequence of identified entities.

A tactical radio includes a radio frequency (RF) processing module having a receiving component path and a transmitting component path. A signal processing module coupled to the RF processing module includes a jammer detection stage for identifying a type of jamming signal on a channel over which communications signals are received simultaneously. A jammer model stage in the signal processing module produces a waveform model for the jamming signal, and a channel model stage replicates propagation conditions on the channel and produces a corresponding cancellation signal. The cancellation signal is coupled at such a level into the receiving component path so as to cancel the jamming signal from received communications signals at the front end of the radio. Any residual jamming signals may then be removed by a secondary jamming cancellation stage operating at baseband.

There is provided a method of parameter estimation in a multi-channel signal environment where a plurality of receive antennas receive signals from one or more transmitters that transmit a signal or wave that is reflected from one or more targets, or receive antennas that receive directly from the transmitters, whose received signals are processed over multiple frequencies or channels by a digital receiver. The method comprises (a) calibrating before the operation of the digital receiver to determine the free parameters of a mathematical model of a channel either as the channel model parameters or in the form of tabulated data; (b) calibrating during the operation of the digital receiver to determine the channel model; (c) comparing received antennas array voltages to an analytic or table driven channel model from a calibrated template without only relying on information lossy intermediate steps such as delay time of arrival or angle of arrival measurements; (d) creating a statistical likelihood function modeling receiver noise to determine model channel parameters or prior channel uncertainty; (e) saving target reflector/emitter parameters to be reused for dynamic tracking; and (f) using Bayesian particle filtering or Maximum Likelihood Methods to update mixture models for the unknown parameters.

The invention discloses a near space dynamic plasma sheath channel modeling and simulating method. The method comprises the steps that channel resources are partitioned according to large-scale space-time-frequency characteristics to construct a large-scale space-time-frequency channel resource matrix, wherein the height corresponds to large-scale space domain characteristics, the speed corresponds to large-scale time domain characteristics, and frequency points correspond to large-scale frequency domain characteristics; for all channel resource matrixes, dynamic small-scale channel parameters are obtained; small-scale channel model simulating is achieved according to given small-scale channel parameters; large-scale channel model simulating is achieved by repeating small-scale channel models at multiple states on a near space flight path. The method is suitable for channel modeling under different dynamic rules, random-amplitude phase probability density distribution which may occurs under a plasma sheath is simulated, and channel modeling feasibility is guaranteed; the method is suitable for near space aircraft plasma sheath channel modeling and spaceflight reentry-return spacecraft plasma sheath channel modeling.

The invention discloses a modeling method specific to an indoor 3D (Three-Dimensional) spatial statistical channel. The modeling method can be applied to a distributed multiple input and multiple output (MIMO) system. When a base station (BS) is designed with a directional antenna, important space-time channel parameters such as Doppler Power Spectrum (DS), space-time correlation and channel capacity are concluded by taking a Poda signal at an MS (Mobile Station) end as a basis; space-time model parameters and the mechanism relationship among included angles of directional antenna main lobes are resolved by using channel space-time feature parameters; meanwhile, the system transmission performance of an MIMO multi-antenna linear array and a circular array under a 3D spatial statistical channel model is researched, so that accurate, flexible diverse channel models are provided for an MIMO multi-antenna space-time processing algorithm and a simulation wireless communication system, and the research of the spatial statistical channel model is expanded.

The invention discloses a space radio-frequency performance test method and a system in a multi-antenna system. More than two antennas are arranged on a dark absorbing chamber; a base station simulator is controlled to send a reference test signal to a device to be tested through a channel simulator and an antenna; when the reference test signal is determined to not satisfy set requirements, the reference test signal is adjusted until the set requirements are satisfied; corresponding test cases are determined according to different channel models; signal simulation is implemented by a channel emulator on the test signal outputted by the base station simulator, and then the test signal is sent to the device to be tested through the antenna; each radio-frequency performance of the device to be tested after the receiving of the test signal is tested according to the radio-frequency performance test items corresponding to the test cases; and when all the radio-frequency performances reach the standard, the space radio-frequency performance reaches the standard. The invention also discloses a space radio-frequency performance test system in the multi-antenna system. The invention is simple to realize and has lower cost.

The invention provides a free space optical communication method and system based on an LDPC code. The method and system aim at a problem that the error rate, communication distance and communication bandwidth of a system are affected by the flicker and light beam drift and extension caused by atmosphere turbulence and the reduction of signal to noise ratio of a receiving end in laser communication. The method comprises the steps: firstly proposing a logarithmic normal distribution channel model under weak turbulence and a K-distribution channel model under strong turbulence according to the characteristics of atmosphere turbulence channels; secondly constructing an irregular QC-LDPC code on the basis of the proposed channel models; finally deducing an LLR probability density function, and carrying out the decoding through an LLR-BP algorithm. A confidence decoding BP result indicates the error rate of the system remarkably decreases along with the increase of signal to noise ratio. An experiment indicates that the method and system can effectively reduce the performance of an FSO system.

The invention provides a joint estimation method of high-precision wireless channel parameterized model, comprising the following steps: reflecting radial component parameter estimation, diffusing radial component parameter estimation, reflecting signal component reestablishment, and diffusing signal component reestablishment. The output of reflecting radial component parameter estimation is negatively fed back to the input of diffusing radial component parameter estimation by reflecting signal component reestablishment; the output of diffusing radial component parameter estimation is negatively fed back to the input of reflecting radial component parameter estimation by diffusing signal component reestablishment; and the output terminals of two parameter estimators self-consistently estimate each parameter of independent components of channel models by such 'butterfly negative feedback' cross iteration mechanism to increase the resolving precision and wideband wireless channel parameterized model. The invention is capable of being applied to the high-precision channel test and modelling of wideband wireless communication systems and digital broadcasting systems, such as WIMAX, LTE, B3G, 4G, UWB and DVB.

The invention discloses a large-scale UAV relay network channel simulation device and a GPU real-time simulation method. The large-scale UAV relay network channel simulation device includes a networknode dynamic topology parameter input unit, a network channel parameter estimation unit, a network channel modeling and generating unit, a network channel combination superposition unit, a network node transmitting signal input unit and a network node receiving signal output unit. The simulation system is flexible and general, and supports the dynamic adjustment of the network size and topology structure; the signal, interference and noise of each relay link are modeled using the equivalent method, the complexity of system simulation is greatly simplified; and for different communication scenes, different nodes are supported to adopt different channel models and updated in real time, the mutual interference between network nodes are considered.

The invention discloses a multi-user and multi-task unloading method based on mobile edge computing, and the method comprises the steps: 1, a multi-user and multi-task scene model is built based on mobile edge computing, and the multi-user and multi-task scene model comprises a system model and a module model; the module model comprises a task model, a channel model, a task unloading model and a computing model of a local and edge server of the mobile equipment; 2, the tasks are unloaded according to task categories and task unloading strategies, wherein the task categories include personal tasks and shared tasks, and the task unloading strategies are obtained by solving with the optimal task processing time delay as the target. By adopting the method, the time delay optimization of the joint processing of the user and the edge server can be realized through mobile edge calculation under the conditions of multiple users and multiple tasks with shared tasks and inseparable tasks.

The invention provides a wireless performance testing system for wireless equipment, belonging to the technical field of wireless performance testing. The wireless performance testing system disclosed by the invention comprises a shielded room, a direction control device, terminal equipment, wireless equipment and a testing antenna; the direction control device, the terminal equipment, the wireless equipment and the testing antenna are arranged in the shielded room; the direction control device can control the direction of the wireless equipment; the terminal equipment is connected with the wireless equipment; the wireless performance testing system further comprises a testing terminal, a multi-path simulator and an adjustable attenuator; one end of the adjustable attenuator is connected with the testing antenna; the other end of the adjustable attenuator is connected with the output end of the multi-path simulator; and the testing terminal is respectively connected with the input end of the multi-path simulator, the adjustable attenuator and the direction control device. The wireless performance testing system disclosed by the invention has the benefits that: a testing environment is steady and reliable; testing data can be repetitive, steady and reliable; the throughput capacities and the whole directionality in an interference-free environment, an interference environment and a practical environment, at different angles and under different attenuations can be tested; and channel models at different angles and the throughput capacities under a multi-path effect can be tested.

The invention relates to a non-stationary V2V MIMO channel modeling method based on geometry. The method comprises the following steps in sequence: establishing a V2V double-loop scattering model; establishing a channel impulse response between the V2V MIMO channel transmitting antenna 1 and the V2V MIMO channel receiving antenna k according to the V2V double-loop scattering model; and according to the geometrical relationship among the mobile transmitting end, the mobile receiving end and the scatterer, time-varying channel parameters of the arrival angle, the departure angle, the Doppler phase shift and the propagation distance of the electric wave are derived. The non-WSS channel model established in the invention is the extension of a stationary double-loop model, and can simulate thenon-stationarity of a V2V channel in a time delay domain and a space domain; parameters such as a scatterer concentration factor, an angle mean value, a vehicle moving speed and an antenna array direction angle comprehensively act on channel statistical characteristics and non-stationary characteristics; the V2V non-stationary channel modeling method is enriched, and the statistical property and non-stationary research of the channel has a practical application value for V2V communication system design and evaluation.

The invention provides a large-scale MIMO system CSI feedback method based on a long-short-term attention mechanism. The method comprises the following steps: firstly, generating sample data of a space-frequency domain channel matrix by using a COST 2100 channel model, and preprocessing the sample data through discrete Fourier transform and truncation operation to obtain a training set and a testset; secondly, establishing an ALSTM-CsiNet channel state information feedback reconstruction model by utilizing an LSTM and an attention mechanism; inputting the training set into an ALSTM-CsiNet channel state information feedback reconstruction model, and performing iterative training on the model by adopting a mean square error and an adaptive estimation gradient descent algorithm to obtain anoptimized ALSTM-CsiNet model; and finally, directly inputting the test set into the ALSTM-CsiNet model to carry out channel state information reconstruction. According to the invention, the LSTM is used to learn the time correlation of the channel, and the attention mechanism is used to perceive the local information and the automatic weighting feature information, so that the channel feedback precision is improved.

The present invention relates to a wireless communication node (20A) adapted to via feeder ports be connected to antenna ports. It comprises signal handling and estimating means (21A) adapted to collect signals from a mobile station and to generate a plurality of channel estimates, connection combination information holding means (22A) adapted to hold information about all possible feeder port-antenna port connections, processing means (24A) comprising channel modelling means (23A) adapted to provide a channel model for the received signals. If further comprises channel model fitting means (25A) adapted to compare the channel model with the channel estimates for a plurality of permutations obtained by the connection combination information and order identifying means (26A) adapted to identify the feeder port connection order corresponding to the permutation order giving the best fit between channel model and channel estimates, hence allowing identification of the order in which the feeder ports actually are connected to the antenna ports.

The invention relates to an adaptive modulation (AM) method design and performance evaluation for a wireless distributed multi-antenna system (DAS). Under the constraint condition of a target bit error rate (BER), the system frequency spectrum efficiency is maximized to respectively design two AM schemes of a discrete rate and a continuous rate. By aiming at the discrete rate AM, an adaptive switching threshold based on precise BER is provided. Compared with the traditional AM based on an approximate threshold, the AM method disclosed by the invention can obtain high frequency spectrum efficiency. A channel model comprising path loss, shadow fading and Rayleigh fading is designed by considering the practical situation of DAS. On the basis, the computation expression of a continuous rate AM frequency spectrum efficiency, a discrete rate AM frequency spectrum efficiency and the average BER is given so as to provide an effective method for system performance evaluation. An Matlab (matrix laboratory) simulation platform shows that the designed AM method can satisfy the target BER requirement, and the continuous rate AM method is better than a discrete rate AM method. In addition, due to the providing of an improved threshold, the discrete rate AM can be used for realizing the high frequency spectrum efficiency if being compared with the traditional AM method. In addition, the provided frequency spectrum efficiency has good consistency with the average BER calculation and simulation, and the system performance can be effectively evaluated.

Three receivers are presented for the general case of noncoherent detection of multi-h continuous phase modulation. All three receivers yield performance gains using multi-symbol observations. The first is an existing receiver which has previously been applied to PCM/FM and is now applied to the Advanced Range Telemetry Tier II waveform. The second and third receivers are presented for the first time in this paper. The existing noncoherent receiver is found to perform poorly (and with high complexity) for the Advanced Range Telemetry Tier II case. For single-symbol observations, the new receivers outperform conventional FM demodulation for both telemetry waveforms, and for multi-symbol observation lengths their performance approaches that of the optimal coherent receiver. The performance is evaluated using computer simulations. Receiver performance is also evaluated using a simple channel model with varying carrier phase. The traditional FM demodulator approach is found to outperform all three receivers as channel conditions worsen.

The invention discloses a double-cluster geometric channel modeling method based on a three-dimensional space. The method comprises the following steps: firstly, building a large-scale MIMO V2V channel model based on a geometric relation in a confocal semi-ellipsoid scattering scene; secondly, using the concept of clusters to describe scatterers, wherein many scatterers exist in the clusters, andthe clusters are randomly distributed on the semi-ellipsoidal surface; supposing that the number of the scatterers in the clusters approaches infinity, and respectively expressing the continuous random variables alphaT<nl,1>, betaT<nl,1>, alphaR<nl,2> and betaR<nl,2> by discrete variables alphaT<l,1>, betaT<l,1>, alphaR<l,2> and betaR<l,2>; then, introducing a birth and death algorithm to simulatedisappearance and evolution of the clusters on a time axis and an array axis; and finally, deducing the statistical characteristics of the proposed channel model according to the complex channel impulse response. The performance of the communication system of the V2V in the semi-ellipsoidal environment is improved by calculating the geometric statistical characteristics of the three-dimensional double-cluster semi-ellipsoidal body.

The invention relates to a method for restraining atmosphere turbulence interference in free-space optical communication, comprising the following steps: loading a user signal on OAM (Operation Administration and Maintenance) light for transmission, transmitting OAM light of multipath loading information in a combined manner through different atmosphere turbulence channels, demultiplexing and demodulating the distorted OAM light of output multipath of each atmosphere turbulence channel at a receiving terminal, as multipath OAM light of a transmitting terminal in a multipath signal transmission model passes through the different atmosphere turbulence channels, and fading characteristics of the respective channels are similar to a multi-antenna fading channel model, a space diversity technology is adopted to restrain the atmosphere turbulence interference, the receiving terminal restores useful signals of respective users to the maximum extent through the demultiplexed and demodulated user information and a space diversity and combination technology, influence of the atmosphere turbulence interference on system-received signals is reduced, and system reliability is improved. Therefore, the invention provides a reference for the practicability of free-space orbit angular momentum multiplexing optical communication.