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Improving the execution time and the numerical complexity of the well-known kurtosis-based maximization method, the RobustICA, is investigated in this paper. A Newton-based scheme is proposed and compared to the conventional RobustICA method. A new implementation using the nonlinear Conjugate Gradient one is investigated also. Regarding the Newton approach, an exact computation of the Hessian of the...
Faster-than-Nyquist (FTN) system provides higher throughput and spectrum efficiency, which is pivotal in future communication. Traditionally in Nyquist system, orthogonality of shaping waveforms is required in order to avoid inter-symbol interference (ISI). However, ISI is permitted in FTN system and thus the advantages of nonorthogonal pulses can be utilized. In this paper, two innovative ones, namely...
The compressed sensing(CS) theory has provided a new solution for the low-rate sampling design of Impulse Radio Ultra-WideBand (IR-UWB) signal. This paper gives full consideration of the influence of quantization noise in IR-UWB system, and designs an effective quantization and reconstruction mechanism with high performance of resisting noise. Based on the analysis of noise distribution characteristics...
This work presents cost-effective low-rank techniques for designing robust adaptive beamforming (RAB) algorithms. At first, we introduce an orthogonal Krylov subspace projection mismatch estimation (OKSPME) method, in which a general linear equation is considered in large dimensions which aims to solve for the steering vector mismatch with known information, then we employ the idea of the full orthogonalization...
Lenstra-Lenstra-Lovász (LLL) is an effective lattice reduction algorithm in multi-input-multi-output (MIMO) system. The usage of LLL lattice reduction can significantly improve the performance of zero-forcing and successive interference cancellation decoders in MIMO communications. But for conventional single channel transmission, when the data streams go through poor channel condition, it usually...
In order to decrease the impact of quantization noise in the low-speed sampling process of IR-UWB (impulse radio ultra-wideband) signal under the compressed sensing framework, based on the equal carry information of compression measurements and characteristics of Gaussian distribution, the paper designs three valid improved quantization mechanisms: overload uniform quantization, non-uniform quantization,...
This work focuses on large scale multi-user MIMO systems in which the base station (BS) outfitted with M antennas communicates with K single antenna user equipments (UEs). In particular, we aim at designing the linear precoder and receiver that maximizes the minimum signal-to-interference-plus-noise ratio (SINR) subject to a given power constraint. To gain insights into the structure of the optimal...
Microwave backhaul links can nowadays deliver rather impressive throughput, however 5G systems will require further higher efficiencies and a promising solution is the so-called faster than Nyqust (FTN) transmission. A FTN communication is obtained when the Nyquist inter-symbol interference (ISI) criterion is not respected because the transmission rate is higher than that for which the shaping filter...
Millimeter wave (mmWave) systems will likely employ large antenna arrays at both the transmitters and receivers. A natural application of antenna arrays is simultaneous transmission to multiple user equipments (UEs), which requires multi-user precoding at the transmitter. However, hardware constraints and operation loads make it challenging to apply conventional pure MIMO digital precoding or even...
In this paper, we take a proposed low-complexity Vertical Bell Laboratories Layered Space Time receiver based on maximal ratio combining and further simplify the algorithm by replacing the channel norm ordering by a power based ordering. The receiver operates in an uplink massive multiple-input-multiple-output deployment with distributed single-antenna users and a large base station (BS) array. The...
In this paper, relay selection schemes in asynchronous multi-relay network for frequency selective channels have been investigated. In particular, distributed Alamouti space time coding and amplify-and-forward (AF) relaying are exploited, and orthogonal frequency division multiplexing (OFDM) is implemented with adaptive cyclic prefix (CP) to deal with the frequency selectivity of the channels and...
The orthogonal frequency division multiplexing (OFDM) system requires precise channel estimation for better system performance. Among various channel estimation methods, the discrete Fourier transform (DFT)-based channel estimation is favored because it has simple architecture and shows as good performance as the linear minimum mean square error (LMMSE) estimation method. However, the DFT itself has...
Maximum-likelihood (ML) receivers are optimum receivers for MIMO systems, but their complexity grows exponentially with the modulation order of the codeword and the number of spatial layers. The Reduced Complexity ML (R-ML) receivers based on low complexity adaptation of the max-log MAP detector and reduction of searching space are a good compromise to satisfy complexity-performance trade-off. In...
In this paper we present the Python LTE Software (PyLTEs), which is a open-source framework for performance evaluation and optimization of the configuration of LTE networks deployment. It allows to define the geographic location of cells, eNodeB configuration such as e.g. TX Power and spatial distribution of the clients. The soft-frequency reuse schemes are supported, as well as different schedulers...
We propose a new approach to signal reconstruction for the time encoding machine introduced by Lazar and Tóth. While practical algorithms of reconstruction from non-uniform samples are mostly based on an ill-posed block treatment of bandlimited signals, we provide a methodology to perform this reconstruction by time-varying FIR filters. Results of SNR versus complexity are given.
This paper presents field test result of an LDM-based mobile broadcasting system, and analyze the results based on reception power (or field strength) and erroneous second ratio (ESR).
The faster decoding algorithm is still required in multiple-input multiple-output (MIMO) wireless communication technology. Lattice reduction (LR) technique can improve the performance of linear MIMO detection methods. LLL (Lenstra-Lenstra-Lovasz) algorithm is one of the LR techniques and it has being extensively used for better basis of channel matrix by removing noise. LR-aided detection algorithms...
In this work, we propose a weighted bit-flipping (WBF) decoding for product LDPC codes of which decoding complexity is lower than the belief-propagation (BP) decoding. Two distinct types based on page computations and row/column computations are proposed. In addition, we address an issue of hard decision algorithm for product LDPC codes suffering a performance degradation at high iteration numbers...
Non uniform constellations have been recently included in the new terrestrial broadcasting system ATSC 3.0, providing better performance than the uniform ones. However, for high order constellations, the complexity in the demapper grows as the number of constellation points do, being necessary to reduce the number of degrees of freedom in the constellation design process. The goal of this paper is...
In this paper, we propose a novel method for channel estimation based on adaptive pilot spacing using low complexity with least-square (LS) channel estimation. Many channel estimation method uses LS or MMSE (Minimum Mean Square Error) channel estimator. The MMSE channel estimation technique suffers from a high computational complexity with an order of O(N - P3) operations ((N - P) represents the total...
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