158 results about "Average signal to noise ratio" patented technology

A method for reporting channel state information (CSI), performed by a beamformee, in a wireless local area network system using multi-channels is provided. The method includes receiving, from a beamformer, an NDP announcement (NDPA) frame announcing that a null data packet (NDP) frame follows the NDPA frame, receiving the NDP frame from the beamformer, estimating a channel from a training symbol of the NDP frame and transmitting to the beamformer a CSI report frame containing a result obtained by estimating the channel, wherein the channel is a multi-channel acquired by aggregating first and second channels which are non-contiguous to each other, and wherein the CSI report frame includes an average signal to noise ratio (SNR) for each space-time stream of the first channel and a steering matrix for each subcarrier of the first channel and an average SNR for each space-time stream of the second channel and a steering matrix for each subcarrier of the second channel.

A Channel Quality Indicator table for wireless multiple input multiple output (MIMO) networks is disclosed. In one embodiment, a method of generating a table for channel quality indicator (CQI) for an open loop MIMO transmission includes calculating performance of a link between a transmitter and a user end unit for each MIMO transmission mode over a range of average signal-to-noise ratio, and selecting the MIMO transmission mode that maximizes performance for each subset of the range of average signal-to-noise ratio. The method further includes storing the selected MIMO transmission mode and the corresponding subset of the range of average signal-to-noise ratio in a CQI table, the CQI table being stored in an user end unit and a base transceiver station of the open loop MIMO network.

The per antenna capacity of each of the transmitter antennas in a MIMO system are individually determined from measurable information at the receiver end. Specifically, the channel capacity for each individual transmitter antenna is calculated at the receiver end as a function of measurable channel coefficients (also known as channel state information), the measurable average signal-to-noise ratio, and the number of transmitter antennas. Once the per antenna capacity of each transmitter antenna is individually determined at the receiver end, the maximum transmission rate for each data stream transmitted by each transmitter antenna is determined from that individual capacity either at the receiver end and fed back to the transmitter end, or is determined at the transmitter end from the individual transmitter antenna capacities that are fed back by the receiver end to the transmitter end. A modulation scheme that supports each maximum transmission rate is then determined based on some defined criteria.

The invention discloses a frequency spectrum cognitive method, cognitive radio user equipment and the structure of a central node in a cognitive radio system. In the frequency spectrum cognitive method, at least one cognitive radio user in the cognitive radio system detects signals of a main user in a selected channel, and sends the detection result to the central node of the cognitive radio system, wherein the detection result is the parameter correlative with the average signal-to-noise ratio of the channel; and the central node combines the detection results from all the cognitive radio users detecting the same channel, makes the conclusive judgment according to the result of the combination to obtain the judgment result on whether the channel is occupied by the main user in a main usersystem, and can further return the result to all the cognitive radio users. Besides, the invention also discloses a method and a device for energy detection.

The invention discloses a closed-loop self-adaptive transmission method used for an uplink of an advanced long-term evolution system. According to the channel status information of the uplink, a mobile terminal selects an appropriate signal transmission mode for adapting to the change of channels. The closed-loop self-adaptive transmission method comprises the steps: a. a base station receives the signals transmitted by a multi-antenna channel, and carries out channel estimation on the received signals at a pilot frequency symbol to obtain link channel parameters in a transmission bandwidth; b. according to the obtained channel parameters, the base station carries out combined selection of ranks (the number of space division multiplexing layers) and precoded matrixes based on the mutual information amount performance criteria, and then carries out modulation coding mode selection according to the mean signal-to-noise ratio mapping criteria, and finally sends the sequence numbers of the selected rank instructions (RI) and the precoded matrixes in a codebook, namely precoded matrix instructions (PMI) and channel quality instructions (CQI) corresponding to the selected modulation coding modes to a feedback channel; and c. the mobile terminal carries out self-adaptive transmission by utilizing the parameters such as RIs, PMIs and CQIs obtained by the feedback channel.

An apparatus and method for partial adaptive transmission in a Multiple-Input Multiple-Output (MIMO) system are provided. The method includes estimating a correlation matrix between Transmit (Tx) antennas and an average Signal to Noise Ratio (SNR) and generating a long-term precoding matrix composed of a predetermined number of dominant eigen dimensions of the correlation matrix by using the estimated correlation matrix and average SNR. The apparatus and method provide a new adaptive MIMO transmission method capable of reducing the feedback information overhead and maximizing performance.

The disclosed speech recognition anti-noise method based on adaptive nonlinear spectrum reduction comprises: detecting speech, if average SNR over set threshold, recognizing as speech information, or else as noise information; updating current noise estimation according to noise frame in last step for the first spectrum reduction calculation to obtain the speech with high SNR; then, taking the second calculation to further eliminate noise.

The invention relates to a hybrid automatic gain control device for a multimode system, which comprises a multimode system control module, a power calculation module, a DATT(digital attenuator) control module, a delay module, a digital down converter module and a gain compensation module, wherein the multimode system control module is used for initializing a mode control signal and a gain compensation control signal; the power calculation module is used for calculating a power of A / D (Analog to Digital) converter data according to the mode control signal; the DATT control module is used for calculating according to the input power to obtain a DATT control signal and regulating an attenuation stepping value of a DATT; the delay module is used for carrying out delay processing on the attenuation stepping value; the digital down converter module is used for processing the A / D converter data to obtain a plurality of single-mode digital signals; and the gain compensation module is used for respectively carrying out gain compensation processing on the single-mode digital signals by using the attenuation stepping value subjected to delay processing according to the gain compensation control signal. The invention also provides a hybrid automatic gain control method. By the hybrid automatic gain control method and the hybrid automatic gain control device, the sensitivity can be prevented from being influenced by the saturation of an ADC (Analog to Digital Converter) or an excessively low power caused by the rapid variation of an uplink signal power, and higher average signal to noise ratio performance is obtained.

The invented method includes following steps with characters of supporting hybrid automatic feed back request (HARQ) technique. In preparing step, the dispatching cycle is fixed. Several adjacent subcarrier waves constitute the sub band. The resource composed of several sub bands is dispatched once a time in each time slot. Then, the mobile station feeds back the word of data rate control (DRC) obtained by quantizing average S / N ratio based on each sub band. In the step of dispatching retransmission data, after calling out the parameters of the scheme at last transmission for retransmission data, the retransmission data are fed back for several transmissions, which have largest DRC, in user's all available sub bands. The invention uses the low error rate of HARQ method and gives attention to both of fairness and system efficiency, and processes low feedback quantity and control amount of information.

The invention provides a centralized MIMO radar radio frequency stealth multi-target tracking wave beam pointing method, and belongs to the technical field of communication radar. Assuming that an interception receiver obeys uniform distribution in a position uncertainty region of the interception receiver, a target function is established with minimization of average signal-to-noise ratio of radar signals received by the interception receiver acting as the target, and the positions of targets are modeled as random quantity so that that probability that echo signal-to-noise ratio of all the targets is great than the preset value is ensured not to be less than a certain value. With application of parameters obtained by optimization of an optimization model, average signal-to-noise ratio of the radar signals received by the interception receiver is enabled to be minimized under the condition of guaranteeing radar echo signal-to-noise ratio performance so that the probability that radar is detected by the interception receiver can be reduced as far as possible.

The invention relates to a signal technique, in particular to a record control technique. The invention discloses a record control method and a record device, for improving the reliability of sound control recording. The record device is provided with at least two audio collection units. The record control method for the record device comprises: obtaining target audio data of prior frame collected by each audio collection unit, and determining the average signal noise ratio of prior frame signals according to the target audio signal of each prior frame; when the average signal noise ratio is higher than a second judgment threshold value of a second setting, storing the target audio data of prior frame collected by each audio collection unit as a record data, while the second judgment threshold value is higher than 1; when the continuous time from the initial frame not satisfying the second setting to prior frame reaches a default time length, stopping storing the target audio data of prior frame collected by each audio collection unit as record data.

The optimal power allocation method for an LSSTC wireless transmission system utilizes Layered Steered Space-Time Codes (LSSTC), a recently proposed multiple-input multiple-output (MIMO) system that combines the benefits of vertical Bell Labs space-time (V-BLAST) scheme, space-time block codes (STBC), and beamforming. A new downlink scheme employs LSSTC with optimal power allocation based on the assumption that the user feeds the base station (BS) with the average signal-to-noise ratio (SNR) per V-BLAST layer through the uplink feedback channel. Such a system enhances the error performance by assigning power to the layers in an optimum manner.

The invention discloses a wireless testing method and a wireless testing system for a GPS (Global Positioning System) of a mobile terminal. The wireless testing method comprises the following steps of: acquiring an average bottom noise value of the mobile terminal in advance; then acquiring an average SNR (Signal to Noise Ratio) value of the mobile terminal by carrying out OTA (Operational Transconductance Amplifier) testing in a hardware environment with low cost according to GPS NMEA (National Marine Electronics Association) log information acquired by testing and a rotating angle of the mobile terminal at each moment; and after carrying out calibration of the average bottom noise value, finally, obtaining the wireless sensitivity of the tested mobile terminal. According to the wireless testing method and system provided by the invention, the hardware testing environment with simple structure can be constructed by low investment and the wireless sensitivity of the mobile terminal is obtained by a series of steps so as to quantitatively estimate the receiving performance and the real using performance of the GPS of the mobile terminal.

A method allows reconfigurable multi-element antennas to select the antenna configuration in MIMO, SIMO and MISO communication system. This selection scheme uses spatial correlation, channel reciprocal condition number, delay spread and average Signal to Noise Ratio (SNR) information to select the antenna radiation pattern at the receiver. Using this approach, it is possible to achieve capacity gains in a multi-element reconfigurable antenna system without modifying the data frame of a conventional wireless communication system. The capacity gain achievable with this configuration selection approach is calculated through numerical simulations using reconfigurable circular patch antennas at the receiver of a MIMO system that employs minimum mean square error receivers for channel estimation. Channel capacity and Bit Error Rate (BER) results show the improvement offered relative to a conventional antenna selection technique for reconfigurable MIMO systems.

The invention discloses a polarity diversity reception method based on an SOQPSK-TG signal. The method comprises the following steps: adopting two ADCs to transfer a received levogyration polarity signal and a received dextrorotation polarity signal into digital signals respectively; adopting an automatic gain control loop to enable the two digital signals to be constant in amplitude or in a threshold value section; tracking frequency difference and phase difference of the two gained digital signals through a difference module loop to fulfill same frequency and phase locking of the two digital signals; adopting maximal-ratio combining to obtain average SNR gain; tracking Doppler frequency shift to conduct carrier recovery; conducting position timing clock recovery; tracking clock phase shift and frequency shift between a receiver and a transmitter. The invention further discloses an SOQPSK-TG signal modulation and polarity diversity reception device based on FPGA. The modulation and reception device utilizes the characteristics of constant envelope and high spectral efficiency of the SOQPSK-TG to meet modern satellite communication demand; the polarity diversity reception technology is introduced to avoid deep zero point influence; system performance is improved.

The embodiment of the invention provides an adaptive modulation transmission method under the high speed mobile environment. The method comprises the steps that a mobile communication system establishes a fast time varying channel model in discrete time so as to obtain the average signal-to-noise ratio, and the average signal-to-noise ratio is transmitted to a transmitter through a feedback link;the transmitter establishes an optimization equation enabling the system average frequency spectrum efficiency to be maximum and meet the constraint according to the change of the average signal-to-noise ratio, the optimization equation is solved to obtain the optimal signal-to-noise ratio threshold value, the signal-to-noise ratio attenuation area subintervals are divided based on the threshold value and the corresponding adaptive power allocation scheme of the subintervals is determined; and the transmitter selects the optimal modulation transmission strategy according to the subintervals and adjusts the transmitting power according to the corresponding power allocation scheme of the subintervals to transmit the next data frame. The system frequency spectrum efficiency can be improved, and the system is ensured to achieve the optimal average throughput so that the problem of significant reduction of adaptive modulation code transmission performance under the condition that the transmitter cannot acquire the accurate channel information can be solved.

An apparatus and method for selecting antennas and nodes in a multi-input multi-output (MIMO) communication system are provided. The apparatus includes a reception unit which detects a communication initiation signal from among a plurality of received signals, a first combination unit which calculates communication capacity based on the communication initiation signal, searches for a combination of transmission antennas that can maximize the communication capacity, and performs communication using the identified combination of transmission antennas, a second combination unit which calculates an average signal-to-noise ratio (SNR) of each node based on the communication initiation signal and selects a node with a highest average SNR and performs communication using the selected node, and a selection unit which activates one of the first combination unit and the second combination unit and inactivates the other combination unit. When the quality of signals transmitted between wireless nodes deteriorates due to a poor channel environment, a node that can minimize the shadowing effect caused by an obstacle that blocks the path of transmission of signals is selected using space diversity. Therefore, it is possible to minimize link communication failures. In addition, it is possible to maximize communication capacity by achieving spatial multiplexing gain using an array antenna that is mounted on a node.

The invention belongs to the technical fields of wireless equipment and network communication, and discloses a cooperative spectrum sensing method based on a trust value and a cognitive radio network.The method comprises the following main steps: making secondary users in a network and a fusion center sense environment parameters; computing an average signal-to-noise ratio, a false alarm probability, path loss, a detection probability, a bit average signal-to-noise ratio, a bit error probability and a probability in reporting a correct sensing result by the fusion center; selecting a trust value threshold and a time window; making the secondary users report sensing results; computing trust values of the secondary users; making a trust value judgment; judging a difference value between theelement quantity of a secondary user set participating in spectrum sensing and the element quantity of a honest user set; and judging a spectrum sensing result to obtain a judgement result. Through adoption of the cooperative spectrum sensing method, various attacks launched by a malicious user can be detected in the case of a non-ideal public control channel; very high robustness is achieved when a large quantity of attackers exist; and the accuracy of spectrum sensing data is ensured.

The invention provides a method of inspecting antenna feeder installation and apparatus therefor which is used for inspecting antenna feeder installation problems according to drive test data. The method comprises following steps: step A, according to each cell pilot frequency S / N in drive test data, the azimythal angle with maxium pilot frequency average S / N in each cell is obtained, and the azimythal angle is used as estimated value of the cell azimythal angle; step B, the antenna feeder installation problems are inspected according to the azimythal angle estimated value of each cell in a base station. The invention judges conditions of feeder installation sequence and transmission diversity of a plurality of cells connected to the same antenna without need of arriving under the base station or climbing to top of the antenna tower, reduces workload of engineering personnel.

The invention discloses a self-adaptive modulation coding beam switching method for a mobile broadband satellite communication system applied to a high-speed railway. The method includes the steps that A, reference threshold values, corresponding to all self-adaptive modulation coding modes, of the signal to noise ratio are determined, according to the channel state information-the receiving signal to noise ratio of the current mobile broadband satellite channel, errors between the value of the receiving signal to noise ratio and the reference threshold values, corresponding to the self-adaptive modulation coding modes, of the signal to noise ratio are calculated, according to the sizes of the errors, the value of the average signal to noise ratio at the receiving end is corrected at different degrees, and the corresponding modulation coding mode is determined according to the size of the average signal to noise ratio obtained through correction; B, if the value of the average signal to noise ratio obtained through correction is smaller than the reference threshold value, corresponding to the lowest-order modulation coding mode, of the signal to noise ratio, a beam is switched. Under the high-speed railway mobile broadband satellite communication environment with fixed lines, the transmission performance of the system is effectively improved, the error rate performance of the system is ensured, and the handling capacity of the system is improved; beam resources are fully used, and frequent and unnecessary beam switching is avoided.

The invention provides a weak signal detection method based on adaptive cascading power function type bistable random resonance, and belongs to the technical field of signal processing. For the purpose of extracting weak signals in the background of strong noise, the invention brings forward a power function type bistable random resonance system by compounding a power function type single-potential-well model with a Gaussian Potential model. According to the method based on the system, first of all, noised signals are preprocessed so as to satisfy small-parameter conditions of a heat insulation approximation theory, then according to known conditions, a search scope of power function type bistable system parameters is arranged, by taking average signal-to-noise gain as a performance average index, values of the power function type bistable system parameters are optimized, and thus an optimal resonance effect is generated. The power function type bistable potential well model brought forward by the invention has the advantages of the power function type single-potential-well model and a conventional bistable model, thereby having general significance in actual application. Searching optimization is carried out on the system parameters by use of an adaptive searching optimization algorithm so that a poor resonance effect caused by poor selection of the system parameters is avoided.

The invention provides a visualization method of radio signal data. The visualization method of the radio signal data comprises a first step of obtaining the radio signal data extracted from frequency spectrum data and original electric level sampling data; a second step of drawing a frequency-bandwidth scatter diagram; a third step of clustering the radio signal data by using a clustering algorithm; a fourth step of dividing time slices; a fifth step of calculating an average center frequency, an average bandwidth, an average signal-to-noise ratio and an average signal intensity of each time slice for each cluster; and a sixth step of drawing a signal flow diagram. Multiple characteristics of radio signals are coded efficiently by utilizing the signal flow diagram, multiple types of important characteristics of relatively scattered signal data at a time frequency are shown smoothly, a multi-characteristic time-varying mode of the radio signal is shown in a better manner, and a macroscopic perceiving efficiency of an analyzer for the radio signal time-varying mode is speeded up.

The invention discloses a wireless communication system link self-adaption transmission method. The wireless communication system link self-adaption transmission method includes two parts, namely, a physical-layer transmission technology configuration method of link self-adaption modulation and coding and the like on the basis of average signal to noise ratio and signal to noise ratio difference factor, and an emission format configuration method applicable to multi-antenna system such as MIMO (multiple input multiple output) communication system on the basis of average signal to noise ratio and average multi-diameter relative energy factor. The wireless communication system link self-adaption transmission method can be used for places where quick link self-adaption technology is inapplicable, not only can be used for a single-antenna system but multi-antenna system and is lower in feed frequency as compared with that of the quick link self-adaption transmission method, load of the system can be reduced and meanwhile, performance of the self-adaption communication system can be effectively improved.

The invention provides an EMD (Empirical Mode Decomposition) based normalization bistable stochastic resonance weak signal detection under oversampling and belongs to the field of signal processing technology. According to the invention, EMD and normalization stochastic resonance are combined into a new system. Signal mode component is superposed for parameter normalization on the basis of EMD ofnoisy signals, so that noisy signals are enabled to meet requirements for stochastic resonance small parameters and are sent to a stochastic resonance system. Whether obvious peaks exist or not is observed through observing a spectrogram and the average SNR gain is calculated. The SNR increases to some extent after EMD and increases once more after stochastic resonance. The total increase is greater than that of using stochastic resonance independently. The EMD based normalization bistable stochastic resonance weak signal detection under oversampling disclosed by the invention has universal meaning in practical application, reduces parameter adjustment complexity and solves a problem that large frequency cannot meet requirements for stochastic resonance.

Techniques are provided for a radio link quality monitoring method and apparatus wherein a given user equipment device receives a plurality of Orthogonal Frequency Division Multiplex symbols that comprise a plurality of resource elements distributed in time and frequency, and which include reference symbols. The objective of the radio link quality monitoring is to predict the user equipment detection probability of control messages transmitted by the base station. The radio link quality estimation process calculates two average signal to noise ratio values over the complete frequency bandwidth for two assumed control channel formats corresponding to in-sync and out-of-sync conditions. The results of the calculations are then used to deduce the average error probabilities that are compared with predefined thresholds to provide the in-sync / out-of-sync indications.

The invention relates to the technology of signal-to-noise ratio estimation, and particularly relates to a signal-to-noise ratio estimation method based on detection reference signal. The signal-to-noise ratio estimation method comprises the following steps: generating a SRS (Sounding Reference Signal) sequence on a frequency domain, and mapping the SRS sequence on a Resource Element (RE) according to mapping manner in LTE (Long Term Evolution) protocol; specifically calculating noise estimation; calculating average signal-to-noise ratio of signal; calculating signal-to-noise ratio of subcarrier. The method disclosed by the invention can be directly applied to SRS, the influence of signal on noise power estimation is reduced by utilizing non-load carrier technology, and the noise power is effectively estimated, so that accurate average signal-to-noise ratio estimation and subcarrier signal-to-noise ratio estimation are obtained.

The invention discloses a channel selection method based on spectrum prediction and perception fusion, which performs statistical estimation on three parameters of average occupancy probability Po, average remaining communicable time length Tl and average signal-to-noise ratio SNR of each channel in channel set C based on historical data of spectrum monitoring. The detection probability of each channel in the channel set C in the prediction stage is obtained by frequency spectrum prediction. By predicting the occupancy of the channel in the future, the unavailable channels are excluded from the sensing queue and the spectrum sensing time is reduced. After the spectrum sensing is completed, the results of spectrum sensing and spectrum prediction are fused according to certain rules, which can reduce the misjudgment caused by missed detection and false alarm, improve the detection performance of channel state, and quickly find high-quality available channels for the link establishment process.

In speech processing systems, compensation is made for sudden changes in the background noise in the average signal-to-noise ratio (SNR) calculation. SNR outlier filtering may be used, alone or in conjunction with weighting the average SNR. Adaptive weights may be applied on the SNRs per band before computing the average SNR. The weighting function can be a function of noise level, noise type, and / or instantaneous SNR value. Another weighting mechanism applies a null filtering or outlier filtering which sets the weight in a particular band to be zero. This particular band may be characterized as the one that exhibits an SNR that is several times higher than the SNRs in other bands.

The invention requests to protect a weak signal detection method driven by color noise and taking cascade tri-stable stochastic resonance as a model, and belongs to the field of signal processing. Taking spectrum peak value and average signal-to-noise ratio as performance indexes, the phenomenon of cascade tri-stable stochastic resonance of high and low frequency signal is studied. The optimal parameters a, b and c are selected by the adaptive algorithm to induce the cascade tri-stable system to generate stochastic resonance. Low-frequency weak signal can be well detected, and the detection effect is the same as that of the secondary sampling high-frequency weak signal. The result shows that when the same system parameters are selected, the stochastic resonance output of the cascade tri-stable system is better than that of the single-stage tri-stable system, and average signal-to-noise ratio gain of single-stage output is smaller than that of the second-stage output in the detection ofhigh-frequency signals. The method has important research significance for weak signal detection and good development prospect.