Spectrum Activity Estimation by Partitionblind Block Partitioned Tensor Decomposition We consider a scenario where signals that can be modeled as finite sums of linearly modulated signals that are nonorthogonal in both time and frequency are observed by a sensor. Under this model, when an antidiagonal slice of the trispectum of the sum of these signals is computed for multiple segments in time and stacked into a frontal symmetric block partitioned tensor (FSBPT) whose factor matrices characterize the received power spectrum and transmission activities of the signals. We propose a new alternating soft thresholding decomposition strategy that is tailored to FSBPTs and, unlike existing BPT decomposition algorithms, simultaneously estimates the factor partitions which is necessary since in our signal model the partitioning is not known a priori. We demonstrate the algorithmxe2x80x99s performance via Monte Carlo simulations. We find that our proposed nonblind algorithm is able to estimate the tensor partitions and moderately accurately estimate the factor matrices under a range of factor matrix column collinearity values.

A TensorBased Spectrum Sensing Technique for MIMO Cognitive Radio Networks Despite the numerous spectrum sensing techniques, the existing techniques fail in providing an efficient spectrum sensing whenever a hidden terminal problem arises. Meanwhile, this problem can happen at any time in any severely fading primarytosecondary channels resulting in very low primary signaltonoise ratios (SNRs) and hence ineffective detection of the primary user in a cognitive radio (CR). Towards overcoming this problem, by introducing a tensorbased hypothesis testing framework, this paper proposes an efficient tensorbased detector (TBD) for a multipleinput multipleoutput (MIMO) CR networks over multipath fading channels. MonteCarlo simulations demonstrate that TBD outperforms the generalized likelihood ratio test (GLRT) detector and maximumminimum eigenvalue (MME) detector, especially in the very low SNR regime which is a manifestation of the hidden terminal problem.