53results about How to "Improve Spectrum Sensing Performance" patented technology

The present invention relates to a wireless communication system and, more particularly, to a spectrum sensing method in cognitive radio communication. According to an aspect of the present invention, a method of canceling an introduced transmission signal includes generating a first signal, having an inverse phase, using a data transmission signal transmitted by a data transmission unit, adjusting a path and/or an amplitude of the first signal, and generating a first signal, having an inverse phase, using a data transmission signal transmitted by a data transmission unit, adjusting a path and/or an amplitude of the first signal, and canceling a second signal, introduced through a data receiving unit, and the first signal by the data transmission signal.

The invention discloses a novel spectrum sensing method and device according to the spectrum sensing problem under the condition of an unknown noise variance in practical application. According to the method and device, combined estimation on the state of an authorized user and the noise variance can be achieved. The sensing algorithm is rooted in the Bayes statistical inference principle, the mariginal particle filtering (MPF) technology is adopted, and the unknown noise variance is approached through an iterative estimation mode. The noise variance information obtained through accurate estimation is utilized, the method and device can be conveniently expanded to be applied to (not limited to) a single-node single-antenna sensing system, and the good spectrum sensing performance is obtained (see the attached drawing). The combined estimating and sensing device has good stability, and therefore the device and method can be widely applied to actual cognitive radio system design.

The invention discloses an asynchronous channel perception method with unknown timing. The asynchronous channel sensing method specifically comprises the following steps: a first step, predicating an existence probability and a perception time difference of a certain PU at a k moment; a second step, updating the existence probability predicted value and the perception time difference via an observation value; a third step, comparing the updated existence probability predicted value with a decision threshold to obtain a state value of the PU; a fourth step, calculating the perception time difference of the PU at the k moment according to the state value; a fifth step, calculating a state value and a weight of a born particle at the k moment according to the perception time difference at a k-1 moment; and a sixth step, judging whether the k moment is the last moment, if so, recording and storing the perception time differences and state values of all moments; and otherwise, iteratively predicting the existence probability and the perception time difference of the PU at a k+1 moment through a particle set at the k moment. The asynchronous channel perception method has the advantages of being suitable for the dynamic spectrum sharing of a heterogeneous wireless network, avoiding the frequent signaling interaction between the PU and SU, reducing the configuration complexity of a CR system and saving the time and the energy cost.

The invention discloses a weighting consistent optimization based broadband distributed cooperative compressed spectrum sensing method, which is characterized in that a weight corresponding to a sub-band on a spectrum signal in the next time of iterative reconstruction is directly set according to a spectrum signal reconstructed by the current iteration, so that the time cost of a spectrum reconstruction stage is effective reduced, and the timeliness of spectrum sensing is enhanced; and the weight corresponding to each sub-band is set according to different characteristics of each sub-band on the spectrum signal, so that a sub-band, on which an authorized user exists, on the spectrum signal is promoted to generate a signal value so as to reduce the error making possibility of spectrum reconstruction and increase the accuracy of spectrum reconstruction, thereby improving the spectrum sensing performance. Under the condition of reaching the same detection probability, the method requires less compressed sampling data, and the corresponding communication cost and sensing time are reduced, so that a sensing user can traverse the whole frequency band quickly and acquire occupation state information of each sub-band, and thus idle sub-bands can be more effectively utilized.

The invention discloses a cooperation detection method used for radio-frequency spectrum sensing and based on diversity combination. According to the cooperation detection method used for radio-frequency spectrum sensing and based on diversity combination, the frequency spectrum usage condition of a main user is detected by each sensing user in a radio system, one sensing user is selected to serve as an information fusion center, maximal-ratio combination of information, obtained through detection, of the sensing users is conducted through the information fusion center, signal energy existing after combination is obtained, a judgment is made by the information fusion center according to the signal energy of a signal obtained after combination, a main user signal exists if the signal energy of the signal obtained after combination is larger than a judgment threshold, and no main user signal exists if the signal energy of the signal obtained after combination is not larger than the judgment threshold. The radio-frequency spectrum sensing type cooperation detection method based on diversity combination, the judgment sensitivity is high, detection is accurate, and the frequency spectrum sensing performance is greatly improved.

The invention discloses an OFDM signal spectrum sensing method for time synchronization and no frequency offset situations. The method comprises the following steps: sampling a received signal from a monitoring channel to obtain a sampling signal; then performing estimation by using the autocorrelation of cyclic prefixs of OFDM signals in the received signal according to the sampling values of all sampling points in the sampling signal in time synchronization and no frequency offset situations to obtain noise power; calculating a covariance matrix of the sampling signal according to the sampling values of the sampling points in the sampling signal; then calculating test statistics according to the noise power and the covariance matrix of the sampling signal; and finally comparing the test statistics with an obtained judgment threshold, and judging whether an authorized user signal exists in the monitoring channel to realize spectrum sensing; and the OFDM signal spectrum sensing method has the advantages of effectively improving the spectrum sensing performance of OFDM signals and ensuring low computational complexity.

The invention discloses an OFDM (Orthogonal frequency division multiplexing) signal spectrum sensing method for asynchronous time without frequency offset. Received signals from monitoring channels are sampled, thereby obtaining sampling signals; estimation is carried out through utilization of the autocorrelation of cyclic prefixes of the OFDM signals in the received signals according to sampling values of all sampling points in the sampling signals under the condition that the time is asynchronous and the frequency offset does not exist, thereby obtaining noise power; a covariance matrix of the sampling signals is calculated according to the sampling values of the sampling points in the sampling signals; the test statistics is calculated according to the noise power and the covariance matrix of the sampling signals; and through comparison of the test statistics and an obtained judgment threshold, whether licensed user signals exist in the monitoring channels or not is judged, thereby realizing spectrum sensing. The method has the advantages that the spectrum sensing performance of the OFDM signals can be effectively improved, and the computing complexity is low.