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Reconfigurable intelligent surface-aided emitter localization
, Article IEEE Sensors Journal ; Volume 22, Issue 22 , 2022 , Pages 21866-21876 ; 1530437X (ISSN) ; Karbasi, S. M ; Behroozi, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
Localization of radio-frequency (RF) transmitters using time difference of arrival (TDOA)-based methods is one of the conventional passive techniques that admits noncooperative source position finding, but suffers from challenging requirements such as precise intersensor synchronization and high-throughput transmission data links. A tradeoff governing the TDOA systems is in the sensor placement configuration. The more distance the sensors are placed, the more accurate localization is carried out, while the cost for the synchronization and data link increases, at the same time. In this work, a novel reconfigurable intelligent surface (RIS)-aided localization system is proposed that enjoys...
Plasmon-induced near-infrared fluorescence enhancement of single-walled carbon nanotubes
, Article Carbon ; Volume 194 , 2022 , Pages 162-175 ; 00086223 (ISSN) ; Tsoulos, T. V ; Sajjadi, S. H ; Antonucci, A ; Wu, S. J ; Tagliabue, G ; Fatmehsari Haghshenas, D ; Boghossian, A. A ; Sharif University of Technology
Elsevier Ltd
2022
Abstract
Single-walled carbon nanotubes (SWCNTs) emit near-infrared (NIR) fluorescence that is ideal for optical sensing. However, the low quantum yields diminish the sensor's signal-to-noise ratio and limits the penetration depths for in vivo measurements. In this study, we perform a systematic investigation of the plasmonic effects of Ag and Au nanoparticles of various geometries to tune and even enhance the fluorescence intensity of single-stranded DNA-wrapped SWCNTs (ssDNA-SWCNTs). We observe a chirality-dependent NIR fluorescence enhancement that varies with both nanoparticle shape and material, with Au nanorods increasing (7, 5) and (7, 6) chirality emissions by 80% and 60% and Ag nanotriangles...
Interference alignment for the k-user MIMO interference channel
, Article IEEE Transactions on Information Theory ; Volume 68, Issue 3 , 2022 , Pages 1401-1411 ; 00189448 (ISSN) ; Motahari, A. S ; Khandani, A. K ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
We consider the K-user Multiple Input Multiple Output (MIMO) Gaussian interference channel with M antennas at each transmitter and N antennas at each receiver. It is assumed that channel coefficients are constant real numbers and are available at all transmitters and at all receivers. The main objective of this paper is to characterize the number of Degrees of Freedom (DoF) of this channel. Using the real interference alignment technique introduced in Motahari et al., 2014, we show that MN M+N K degrees of freedom can be achieved for almost all channel realizations. Also, a new upper-bound on the DoF of this channel is provided. This upper-bound coincides with our achievable DoF for K K u...
Xavier-Enabled extreme reservoir machine for millimeter-wave beamspace channel tracking
, Article 2022 IEEE Wireless Communications and Networking Conference, WCNC 2022, 10 April 2022 through 13 April 2022 ; Volume 2022-April , 2022 , Pages 1683-1688 ; 15253511 (ISSN); 9781665442664 (ISBN) ; Mili, M. R ; Rasti, M ; Nardelli, P. H. J ; Bennis, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
In this paper, we propose an accurate two-phase millimeter-Wave (mmWave) beamspace channel tracking mechanism. Particularly in the first phase, we train an extreme reservoir machine (ERM) for tracking the historical features of the mmWave beamspace channel and predicting them in upcoming time steps. Towards a more accurate prediction, we further fine-tune the ERM by means of Xavier initializer technique, whereby the input weights in ERM are initially derived from a zero mean and finite variance Gaussian distribution, leading to 49% degradation in prediction variance of the conventional ERM. The proposed method numerically improves the achievable spectral efficiency (SE) of the existing...
Feasibility of a novel beamforming algorithm via retrieving spatial harmonics
, Article Journal of Systems Engineering and Electronics ; Volume 33, Issue 1 , 2022 , Pages 38-46 ; 16711793 (ISSN) ; Azmi, P ; Nasirian, M ; Sharif University of Technology
Beijing Institute of Aerospace Information
2022
Abstract
This paper introduces an algorithm for beamforming systems by the aid of multidimensional harmonic retrieval (MHR). This algorithm resolves problems, removes limitations of sampling and provides a more robust beamformer. A new sample space is created that can be used for estimating weights of a new beamforming called spatial-harmonics retrieval beamformer (SHRB). Simulation results show that SHRB has a better performance, accuracy, and applicability and more powerful eigenvalues than conventional beamformers. A simple mathematical proof is provided. By changing the number of harmonics, as a degree of freedom that is missing in conventional beamformers, SHRB can achieve more optimal outputs...
Optimization of some experimental parameters in the electro membrane extraction of chlorophenols from seawater
, Article Journal of Chromatography A ; Volume 1216, Issue 45 , 2009 , Pages 7687-7693 ; 00219673 (ISSN) ; Khalilian, F ; Bagheri, H ; Lee, H. K ; Sharif University of Technology
2009
Abstract
An electro membrane extraction (EME) methodology was utilized to study the isolation of some environmentally important pollutants, such as chlorophenols, from aquatic media based upon the electrokinetic migration process. The analytes were transported by application of an electrical potential difference over a supported liquid membrane (SLM). A driving force of 10 V was applied to extract the analytes through 1-octanol, used as the SLM, into a strongly alkaline solution. The alkaline acceptor solution was subsequently analyzed by high performance liquid chromatography-ultraviolet (HPLC-UV) detection. The parameters influencing electromigration, including volumes and pH of the donor and...
Impact of channel estimation errors and power allocation on analog network coding and routing in two-way relaying
, Article IEEE Transactions on Vehicular Technology ; Volume 61, Issue 7 , May , 2012 , Pages 3223-3239 ; 00189545 (ISSN) ; Sadeghi, P ; Hucher, C ; Pakravan, M. R ; Sharif University of Technology
IEEE
2012
Abstract
In this paper, we study two important transmission strategies in full-duplex two-way relaying in the presence of channel estimation errors. In analog network coding (ANC), the relay transmits the combined signals that were received from both sources, with the aim of achieving better spectral efficiency. However, due to imperfect channel-state information (CSI), sources cannot perfectly cancel their own data in the relayed signal. We derive an achievable information rate for ANC in imperfect-CSI conditions and show how the ANC performance can significantly be degraded as a result. Moreover, we derive cut-set bounds with channel estimation errors for traditional routing (TR), in which time...
Error control for multimedia communications in wireless sensor networks: A comparative performance analysis
, Article Ad Hoc Networks ; Volume 10, Issue 6 , 2012 , Pages 1028-1042 ; 15708705 (ISSN) ; Rabiee, H. R ; Khansari, M ; Salehi, M ; Sharif University of Technology
Abstract
The emerging multimedia applications of Wireless Sensor Network (WSNs) impose new challenges in design of algorithms and communication protocols for such networks. In the view of these challenges, error control is an important mechanism that enables us to provide robust multimedia communication and maintain Quality of Service (QoS). Despite the existence of some good research works on error control analysis in WSNs, none of them provides a thorough study of error control schemes for multimedia delivery. In this paper, a comprehensive performance evaluation of Automatic Repeat Request (ARQ), Forward Error Correction (FEC), Erasure Coding (EC), link-layer hybrid FEC/ARQ, and cross-layer hybrid...
Topological pattern selection in recurrent networks
, Article Neural Networks ; Volume 31 , 2012 , Pages 22-32 ; 08936080 (ISSN) ; Abbassian, A ; Sharif University of Technology
2012
Abstract
The impact of adding correlation to a population of neurons on the information and the activity of the population is one of the fundamental questions in recent system neuroscience. In this paper, we would like to introduce topology-based correlation at the level of storing patterns in a recurrent network. We then study the effects of topological patterns on the activity and memory capacity of the network. The general aim of the present work is to show how the repertoire of possible stored patterns is determined by the underlying network topology.Two topological probability rules for pattern selection in recurrent network are introduced. The first one selects patterns according to a...
MIMO radar waveform design in the presence of clutter
, Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 47, Issue 2 , 2011 , Pages 770-781 ; 00189251 (ISSN) ; Behnia, F ; Sharif University of Technology
Abstract
Waveform design for target identification and classification in multiple-input multiple-output (MIMO) radar systems has been studied in several recent works. In previous works, optimal signals for an estimation algorithm are found assuming that only signal- independent noise exists. This work extends previous research by studying the case where clutter is also present. We develop a procedure to design the optimal waveform which minimizes estimation error at the output of the minimum mean squared error (MMSE) estimators in two scenarios. In the first one different transmit antennas see uncorrelated aspects of the target, and we consider the correlated target aspects in the second one....
Outage probability and power allocation of amplify and forward relaying with channel estimation errors
, Article IEEE Transactions on Wireless Communications ; Volume 10, Issue 1 , November , 2011 , Pages 124-134 ; 15361276 (ISSN) ; Sadeghi, P ; Pakravan, M. R ; Sharif University of Technology
2011
Abstract
This paper studies the statistical properties of the signal-to-noise ratio (SNR) of the dual-hop relaying link in a cooperative wireless communication system in the presence of channel estimation errors for fixed-gain (FG) and variable-gain (VG) relays. The SNR expression is derived and three different analytical approaches with different simplifying assumptions are proposed to obtain the probability distribution function of the SNR and the outage probability in each mode. All but one approach result in closed-form expressions for the outage probability. The simplest approach in each mode has been used to find an optimum power allocation scheme for pilot and data symbols transmission at the...
Performance evaluation of asynchronous multi-carrier code division multiple access for next-generation long-reach fibre optic access networks
, Article IET Optoelectronics ; Volume 9, Issue 6 , 2015 , Pages 325-332 ; 17518768 (ISSN) ; Beyranvand, H ; Salehi, J. A ; Sharif University of Technology
Institution of Engineering and Technology
2015
Abstract
In this study, the authors evaluate the performance of asynchronous optical multi-carrier code division multiple access (MC-CDMA) for intensity modulated/direct detection systems to be used in next-generation optical access networks. The proposed system employs Gold sequence in frequency-domain to provide asynchronous resource sharing. In long-reach passive optical networks, fibre impairments degradation to the performance of ordinary optical CDMA can be avoided by frequency-domain digital compensation methods in the proposed MC-CDMA. In comparison with orthogonal frequency division multiple access, peak-to-average power ratio in the proposed MC-CDMA is reduced and asynchronous resource...
Knowledge-based design of space-time transmit code and receive filter for a multiple-input-multiple-output radar in signal-dependent interference
, Article IET Radar, Sonar and Navigation ; Volume 9, Issue 8 , 2015 , Pages 1124-1135 ; 17518784 (ISSN) ; Aubry, A ; Carotenuto, V ; Naghsh, M. M ; Bastani, M. H ; Sharif University of Technology
Institution of Engineering and Technology
2015
Abstract
The authors deal with the robust design of multiple-input-multiple-output (MIMO) space-time transmit code (STTC) and space-time receive filter (STRF) for a point-like target embedded in signal-dependent interference. Specifically, they assume that the radar exploits knowledge provided by dynamic environmental database, to roughly predict the actual scattering scenario. Then, they devise an iterative method to optimise the (constrained) STTC and the (constrained) STRF which sequentially improves the worst-case (over interfering scatterers statistics) signal-to-interference-plus-noise ratio (SINR). Each iteration of the algorithm is handled via solving two (hidden) convex optimisation...
Cooperative transmission for wireless relay networks using limited feedback
, Article IEEE Transactions on Signal Processing ; Volume 58, Issue 7 , Jun , 2010 , Pages 3828-3841 ; 1053587X (ISSN) ; Khalaj, B. H ; Gershman, A. B ; Sharif University of Technology
2010
Abstract
To achieve the available performance gains in half-duplex wireless relay networks, several cooperative schemes have been earlier proposed using either distributed space-time coding or distributed beamforming for the transmitter without and with channel state information (CSI), respectively. However, these schemes typically have rather high implementation and/or decoding complexities, especially when the number of relays is high. In this paper, we propose a simple low-rate feedback-based approach to achieve maximum diversity with a low decoding and implementation complexity. To further improve the performance of the proposed scheme, the knowledge of the second-order channel statistics is...
Rate-distortion optimization of scalable video codecs
, Article Signal Processing: Image Communication ; Volume 25, Issue 4 , 2010 , Pages 276-286 ; 09235965 (ISSN) ; Rabiee, H. R ; Ghanbari, M ; Sharif University of Technology
Abstract
In this paper joint optimization of layers in the layered video coding is investigated. Through theoretical analysis and simulations, it is shown that, due to higher interactions between the layers in a SNR scalable codec, this type of layering technique benefits most from joint optimization of the layers. A method for joint optimization is then proposed, and its compression efficiency is contrasted against the separate optimization and an optimized single layer coder. It is shown that, in joint optimization of SNR scalable coders when the quantization step size of the enhancement layer is larger than half the step size of the base layer, an additional improvement is gained by not sending...
Analytical studies of fragmented-spectrum multi-level OFDM-CDMA technique in cognitive radio networks
, Article 7th IEEE Annual Ubiquitous Computing, Electronics and Mobile Communication Conference, UEMCON 2016, 20 October 2016 through 22 October 2016 ; 2016 ; 9781509014965 (ISBN) ; Sharifi Malvajerdi, S ; Poursaeed, O ; Salehi, J. A
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
In this paper, we present a multi-user resource allocation framework using fragmented-spectrum synchronous OFDM-CDMA modulation over a frequency-selective fading channel. In particular, given pre-existing communications in the spectrum where the system is operating, a channel sensing and estimation method is used to obtain information of subcarrier availability. Given this information, some real-valued multi-level orthogonal codes, which are orthogonal codes with values of {±1, ±2, ±3, ±4,...}, are provided for emerging new users, i.e., cognitive radio users. Additionally, we have obtained a closed form expression for bit error rate of cognitive radio receivers in terms of detection...
A 38 pJ/b optimal soft-MIMO detector
, Article IEEE Transactions on Circuits and Systems II: Express Briefs ; Volume 64, Issue 9 , 2017 , Pages 1062-1066 ; 15497747 (ISSN) ; Doostnejad, R ; Mahdavi, M ; Gulak, P. G ; Sharif University of Technology
Abstract
An optimal soft multiple-input multiple-output (MIMO) detector is proposed with linear complexity for a general spatial multiplexing system with two transmitting symbols and NR 2 receiving antennas. The computational complexity of the proposed scheme is independent of the operating signal-to-noise ratio and grows linearly with the constellation order. It provides the soft maximum-likelihood solution using an efficient log-likelihood ratio calculation method, avoiding the exhaustive search on all the candidate nodes. Moreover, an efficient pipelined hardware implementation of the detection algorithm is proposed, which is fabricated and fully tested in a 130-nm CMOS technology. Operating at...
Resource allocation and power control for underlay device-to-device communication in fractional frequency reuse cellular networks
, Article Telecommunication Systems ; Volume 65, Issue 4 , 2017 , Pages 677-697 ; 10184864 (ISSN) ; Khazali, A ; Kalbkhani, H ; Shayesteh, M. G ; Solouk, V ; Sharif University of Technology
Springer New York LLC
2017
Abstract
The current state of device-to-device (D2D) communication in the presence of cellular network addresses two major challenges of interference as well as throughput inadequacy. Specifically, a D2D communication underlaying fractional frequency reuse (FFR) cellular network exhibits rather high interferences due to higher occurrence of band crossing within a shared spectrum. However, due to the considerable impact of D2D communications on spectral efficiency and system capacity, the remedy for those issues may include efficient techniques of interference mitigation and average spectral efficiency maximization. In this paper, we propose a resource block (RB) allocation scheme to reduce the...
Energy-efficient fast configuration of flexible transponders and grooming switches in OFDM-based elastic optical networks
, Article Journal of Optical Communications and Networking ; Volume 10, Issue 2 , 2018 , Pages 90-103 ; 19430620 (ISSN) ; Pakravan, M. R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
We investigate the problem of energy-efficient resource allocation constrained to quality of service and physical requirements in orthogonal frequency division multiplexing (OFDM)-based elastic optical networks and propose a fast two-stage algorithm to solve it. The first stage of the proposed algorithm deals with routing, traffic grooming, and traffic ordering and mainly aims at minimization of the number of deployed optical amplifiers and transponders. We provide an integer linear program for routing and traffic grooming and propose a heuristic procedure, which yields its near-optimum solution in a shorter runtime. In the second stage, we optimize transponder parameters to minimize total...
Statistical properties of amplify and forward relay links with channel estimation errors
, Article Proceedings of the 2009 Australian Communications Theory Workshop, AusCTW 2009, 4 February 2009 through 7 February 2009, Sydney, NSW ; 2009 , Pages 44-49 ; 9781424433575 (ISBN) ; Pakravan, M. R ; Sadeghit, P ; Lamahewat, T ; Australian National University ; Sharif University of Technology
2009
Abstract
This paper studies the statistical properties of the signal-to-noise ratio (SNR) of the relay link in a cooperative wireless communication system with fixed gain relay in presence of channel estimation error. The SNR expression is derived and three different analytic approaches with different approximate assumptions are used to obtain the probability distribution function of the SNR and outage probability of the relay link. The first approach is the most accurate one in many cases, however it does not have a closed-form expression. The other two approaches result in closed-form expressions for the outage probability. Therefore, the third approach has been used to find a sub-optimum power...