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In this paper, we consider the uplink of cell-free massive MIMO systems, where a large number of distributed single antenna access points (APs) serve a much smaller number of users simultaneously via limited backhaul. For the first time, we investigate the performance of compute-and-forward (C&F) in such an ultra dense network with a realistic channel model (including fading, pathloss and shadowing)...
Polar code has become a major milestone in information theory field in recent times. Researchers are still observing more efficient encoding and decoding structures. In this study, a new WIB based structure is proposed which reduces the computational complexity of WIB introduced as an early termination method for BP polar decoder in literature. Both proposed and WIB methods are implemented with VHDL...
Millimeter wave (mm-wave) system performance may be degraded if the operation mechanism is not properly designed, because mm-wave systems suffer severe path loss and very short coherence time. Thanks to the sparse channel model and directional transmission property, it is usually sufficient to use analog beam codebooks in beam training to estimate dominant channel components instead of complete instantaneous...
For improving MIMO radar detection probability of weak target, this paper proposes a tracking before detecting (TBD) algorithm based on successive target cancellation-dynamic programming (STC-DP). The algorithm extracts signals' sufficient statistic which is used to screens the track points and integrates signals, reducing complexity. Then in case of unknown the number of target, detect targets effectively...
As compared to the FFT, the recently introduced Sparse Fourier Transform (SFT) achieves substantial reduction in the complexity of detecting frequencies in signals that are sparse in the frequency domain. However, the SFT requires the significant frequencies to be on the grid and the exact sparsity of the signal to be known. In this paper, we propose a framework that overcomes these issues. Our method...
The decoding performance of polar codes strongly depends on the decoding algorithm used, while also the decoder throughput and its latency mainly depend on the decoding algorithm. In this work, we implement the powerful successive cancellation list (SCL) decoder on a GPU and identify the bottlenecks of this algorithm with respect to parallel computing and its difficulties. The inherent serial decoding...
Massive MIMO has the potential to bring great spectral and energy efficiency improvements, making it a very promising technology for future wireless systems. Essential to achieve the gains in practice, is the ability to realize the many antenna paths at low complexity. In this paper, we consider the potential of processing at the semiconductor edge by allowing voltage over-scaling and complete antenna...
Analog-to-digital (A/D) conversion plays a crucial role when it comes to the design of energy-efficient and fast signal processing systems. As its complexity grows exponentially with the number of output bits, significant savings are possible when resorting to a minimum resolution of a single bit. However, then the nonlinear effect which is introduced by the A/D converter results in a pronounced performance...
We introduce maximum-SINR sparse-binary waveforms that modulate data information symbols from any finite alphabet and span the whole continuum of the available/device-accessible spectrum. We offer an optimal algorithm that designs the proposed waveforms by maximizing the signal-to-interference-plus-noise ratio (SINR) at the output of the maximum-SINR linear receiver. In addition, we offer a suboptimal...
Although Wireless Gigabit (WiGig) access operating in the 60 GHz band plays a significant role towards multi-Gbps WLANs, its transmission suffers from harsh propagation loss and path blocking reducing its transmission range to be few meters around a WiGig access point/station (AP/STA). Consequently, directional transmissions using antenna beamforming is tremendously used in WiGig communication. In...
In this paper, a low complexity MIMO detection is proposed for MIMO-Constant Envelope Modulation (MIMO-CEM) transceiver system. In which, an adaptive sphere decoder (SD) based on an affine linear transformation model is proposed to adaptively select a small number of candidate sequences from all lattice states. Then, the more accurate (the more complex) IF based maximum likelihood MIMO-CEM decoder...
The goal of this paper is to investigate the performance of MIMO-WCDMA networks, where Principal Component Analysis (PCA) is employed at the reception. Multipath propagation is exploited, as the individual received signals can be seen as different instances of the same physical phenomenon (i.e. transmission and reception of WCDMA sequences). In this context, the received data are first transformed...
The resource allocation problem is investigated for an Uplink OFDMA based system. The subcarrier and power allocation issue was formulated as an optimization problem with the objective of maximizing the overall system rate, and maintaining a minimum rate for every user, so that fairness is addressed. Two level dual decomposition algorithm was adopted to derive the optimal power and subcarrier, while...
With increasing data rates in communication systems, the call for wideband transceiver solutions capable of processing complex modulation schemes is getting stronger. Unfortunately, this goes along with power hungry systems and more complex integrated circuits. A novel receiver architecture, which addresses these issues, is based on the simultaneous phase and amplitude regenerative sampling system...
Abstract-We consider the problem of designing constellation sets for multistage systems for high spectral efficiencies. In particular we will focus on two-stage systems where the cascaded decoding stages are associated to three types of receivers with different complexities and performances. The optimal receiver (S) processes the symbol LLR and delivers the maximum possible throughput, the simpler...
This paper explores means of reducing the complexity of a Sparse Code Multiple Access (SCMA) decoder. SCMA was proposed to assist massive connectivity in 5G future wireless telecommunication standards. The existing SCMA decoding algorithm is based on the Message Passing Algorithm (MPA). It heavily relies on calculations of the exponential function to estimate the maximum likelihood decoded message...
We provide an optimization of the performance of joint transmit precoding and transmit antenna selection for spatial modulation. We show that the joint optimization problem out-performs the separate optimization problem by up to 1 dB. The performance of different optimization schemes with varying computational complexity is simulated and we discuss their individual advantages.
The improved multiband-structured subband adaptive filter (IMSAF) algorithm could enhance the convergence performance of multiband-structured subband adaptive filter algorithms and affine projection. However, the original IMSAF algorithm with a fixed step-size factor have to compromise between convergence rate and steady-state misalignment. A new IMSAF algorithm with variable step-size matrix (VSM)...
Recently, the need to extra frequency bands is increasing significantly due to modern devices and applications. This problem can be addressed by exploiting the idle spectra. Thus, the spectrum exploiting is performed using the technique of spectrum sensing. In this paper, a new cooperative spectrum sensing scheme is proposed based on discrete cosine transform periodogram. This scheme is applied on...
Fine frequency estimation of a single complex sinusoid is considered. We propose to refine the frequency estimation provided by the state-of-the-art methods based on three discrete Fourier transform (DFT) samples around the DFT maximum. To that end, parabolic interpolation of the periodogram peak is used. With the calculation of only three additional periodogram samples, the Cramér-Rao lower bound...
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