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Deep Neural Network Based Blind Estimation of Reverberation Time Based on Multi-channel Microphones
Lee, Myungin,Chang, Joon-Hyuk S. Hirzel Verlag 2018 Acta acustica united with Acustica Vol.104 No.3
<P>Reverberation causes a performance degradation in distinct speech processing. For this reason, quantitatively estimating the amount of reverberation from the signal received by the microphone has been an important task for characterizing room acoustics and compensating for degradation due to an algorithm. In this paper, a novel method that estimates the reverberation time (T-60) based on multi-channel microphones using a deep neural network (DNN) is proposed. Each channel's distribution of the decay rates for each frequency and the generalized cross-correlation with phase transform (GCC-PHAT) between the microphones are adopted as the input feature vectors for DNN training. Those refined features enable the DNN composed of multiple nonlinear hidden layers to learn the nonlinear relationship that labels the reverberation time from the input features, which is known to be challenging with low-order features. The proposed algorithm is evaluated with extensive noisy conditions, and the results show the advantage of employing multi-channel signals with spatial features when compared with conventional methods.</P>
Ko, D.,Koo, K.,Kim, D.Y. S. Hirzel Verlag 2016 International journal of electronics and communica Vol.70 No.9
RaptorQ codes, a class of fountain codes, are widely used as a way to achieve forward error correction at the application layer. Whereas RaptorQ codes perform impressively in terms of symbol recovery, its high computational complexity limits its applicability in demanding real-time scenarios. As a way to resolve this inefficiency, we propose using a novel matrix structure designed to reduce the decoding complexity of RaptorQ codes. Specifically, we replace Luby Transform codes and Low-density Parity Check (LDPC) codes in RaptorQ code operations using a novel binary matrix based on Kolchin's Theorem. Our proposed improvements remove the need for LDPC codes to decrease the dimension of the matrix, and it reduces the latency resulting from matrix inversions. Given that the resulting latency from this process dominates the entire RaptorQ code decoding process, our changes offer the potential for reducing the latency dramatically. Based on an extensive set of simulations using our proposed matrix structure under various configurations, we show that the proposed decoding latency is faster than that of RaptorQ codes, while maintaining an at-par decoding-failure probability.
User clustering and robust beamforming design in multicell MIMO-NOMA system for 5G communications
Chinnadurai, S.,Selvaprabhu, P.,Jeong, Y.,Sarker, A.L.,Hai, H.,Duan, W.,Lee, M.H. S. Hirzel Verlag 2017 International journal of electronics and communica Vol.78 No.-
In this paper, we present a robust beamforming design to tackle the weighted sum-rate maximization (WSRM) problem in a multicell multiple-input multiple-output (MIMO) - non-orthogonal multiple access (NOMA) downlink system for 5G wireless communications. This work consider the imperfect channel state information (CSI) at the base station (BS) by adding uncertainties to channel estimation matrices as the worst-case model i.e., singular value uncertainty model (SVUM). With this observation, the WSRM problem is formulated subject to the transmit power constraints at the BS. The objective problem is known as non-deterministic polynomial (NP) problem which is difficult to solve. We propose an robust beamforming design which establishes on majorization minimization (MM) technique to find the optimal transmit beamforming matrix, as well as efficiently solve the objective problem. In addition, we also propose a joint user clustering and power allocation (JUCPA) algorithm in which the best user pair is selected as a cluster to attain a higher sum-rate. Extensive numerical results are provided to show that the proposed robust beamforming design together with the proposed JUCPA algorithm significantly increases the performance in term of sum-rate as compared with the existing NOMA schemes and the conventional orthogonal multiple access (OMA) scheme.