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Open Access Article
1 - BER Performance Analysis of MIMO-OFDM Communication Systems Using Iterative Technique Over Indoor Power Line Channels in an Impulsive Noise Environment
Mohammad Reza Ahadiat Paeez Azmi Afrooz HaghbinThis paper addresses the performance of MIMO-OFDM communication system in environments where the interfering noise exhibits non-Gaussian behavior due to impulsive phenomena. It presents the design and simulation of an iterative technique that aims to minimize the effect MoreThis paper addresses the performance of MIMO-OFDM communication system in environments where the interfering noise exhibits non-Gaussian behavior due to impulsive phenomena. It presents the design and simulation of an iterative technique that aims to minimize the effect of impulsive noise on the performance of the MIMO-OFDM communication system under Additive White Gaussian Noise (AWGN) channel. This is a new method to recover the signals corrupted by impulsive noise in MIMO-OFDM systems over In-home Power Line Channel. The location and amplitude Impulsive noise at the receiver using an adaptive threshold to be determined. Reduced Impulsive noise effects using the mask based on the soft decision method. By iteration, the original signal estimation can be used to improve the impulsive noise estimation. This continuous loop impulsive noise detection and mitigation a better estimate of the original signal is obtained. The Bit Error Rate (BER) performance of the MIMO-OFDM system in an impulsive noise environment was evaluated. The results show the superiority and robustness of the proposed method. Manuscript profile -
Open Access Article
2 - Target Tracking in MIMO Radar Systems Using Velocity Vector
Mohammad Jabbarian Jahromi Hossein Khaleghi BizakiThe superiority of multiple-input multiple-output (MIMO) radars over conventional radars has been recently shown in many aspects. These radars consist of many transmitters and receivers located far from each other. In this scenario, the MIMO radar is able to observe the MoreThe superiority of multiple-input multiple-output (MIMO) radars over conventional radars has been recently shown in many aspects. These radars consist of many transmitters and receivers located far from each other. In this scenario, the MIMO radar is able to observe the targets from different directions. One of the advantages of these radars is exploitation of Doppler frequencies from different transmitter-target-receiver paths. The extracted Doppler frequencies can be used for estimation of target velocity vector so that, the radar can be able to track the targets by use of its velocity vector with reasonable accuracy. In this paper, two different processing systems are considered for MIMO radars. First one is the pulse Doppler system, and the second one is continuous wave (CW) system without range processing. The measurement of the velocity vector of the target and its counterpart errors are taken into account. Also, the extended Kalman target tracking by using its velocity vector is considered. Besides, its performance is compared with those of MIMO target tracking without using the velocity vector and conventional radars. The simulation results show that the MIMO radars using velocity vector have superior performance over other above-mentioned radars in fast maneuvering target tracking. Since the range processing is ignored in CW MIMO radar systems, the complexity of this system is much lower than that of Pulse Doppler MIMO radar system, but has lower performance in tracking fast maneuvering target. Manuscript profile -
Open Access Article
3 - A New Cooperative Approach for Cognitive Radio Networks with Correlated Wireless Channels
Mehdi Ghamari Adian Hassan AghaeeniaAn effective cooperative cognitive radio system is proposed, when the wireless channels are highly correlated. The system model consists of two multi-antenna secondary users (SU TX and SU RX), constituting the desired link and some single-antenna primary and secondary u MoreAn effective cooperative cognitive radio system is proposed, when the wireless channels are highly correlated. The system model consists of two multi-antenna secondary users (SU TX and SU RX), constituting the desired link and some single-antenna primary and secondary users. The objective is the maximization of the data rates of the desired SU link subject to the interference constraints on the primary users. An effective system, exploiting Transmit Beamforming (TB) at SU TX, cooperation of some single-antenna SUs and Cooperative Beamforming (CB) at them and the antenna selection at SU RX to reduce the costs associated with RF-chains at the radio front end at SU RX, is proposed. Due to the issue of MIMO channels with correlated fading, some problems arise such as inapplicability of the well-known Grassmanian Beamforming as TB scheme at SU TX. We then propose a method to overcome this problem. After formulating the problem, a novel iterative scheme is proposed to find the best TB weight vector in SU TX and best subset of antennas at SU RX, considering the correlated channel. Manuscript profile -
Open Access Article
4 - Multiple Antenna Relay Beamforming for Wireless Peer to Peer Communications
Mohammad Hossein Golbon Haghighi Behrad Mahboobi Mehrdad ArdebilipourThis paper deals with optimal beamforming in wireless multiple-input-multiple-output (MIMO) relay networks that involves multiple concurrent source-destination pairs with imperfect channel state information (CSI) at the relays. Our aim is the optimization of the MIMO re MoreThis paper deals with optimal beamforming in wireless multiple-input-multiple-output (MIMO) relay networks that involves multiple concurrent source-destination pairs with imperfect channel state information (CSI) at the relays. Our aim is the optimization of the MIMO relay weights that minimize the total relay transmit power subject to signal-to-interference-plus-noise ratio (SINR) of all destinations to be kept above a certain threshold. Since power minimization is a non-convex quadratically constrained quadratic programming (QCQP), we use semi-definite programming (SDP) relaxation of above mentioned problem by using a randomization technique. Numerical Monte Carlo simulations verify the performance gain of our proposed multiple antenna relay system in terms of transmit power and symbol error probability. Manuscript profile -
Open Access Article
5 - Joint Relay Selection and Power Allocation in MIMO Cooperative Cognitive Radio Networks
Mehdi Ghamari Adian Hassan AghaeeniaIn this work, the issue of joint relay selection and power allocation in Underlay MIMO Cooperative Cognitive Radio Networks (U-MIMO-CCRN) is addressed. The system consists of a number of secondary users (SUs) in the secondary network and a primary user (PU) in the prima MoreIn this work, the issue of joint relay selection and power allocation in Underlay MIMO Cooperative Cognitive Radio Networks (U-MIMO-CCRN) is addressed. The system consists of a number of secondary users (SUs) in the secondary network and a primary user (PU) in the primary network. We consider the communications in the link between two selected SUs, referred to as the desired link which is enhanced using the cooperation of one of the existing SUs. The core aim of this work is to maximize the achievable data rate in the desired link, using the cooperation of one of the SUs which is chosen opportunistically out of existing SUs. Meanwhile, the interference due to the secondary transmission on the PU should not exceed the tolerable amount. The approach to determine the optimal power allocation, i.e. the optimal transmits covariance and amplification matrices of the SUs, and also the optimal cooperating SU is proposed. Since the proposed optimal approach is a highly complex method, a low complexity approach is further proposed and its performance is evaluated using simulations. The simulation results reveal that the performance loss due to the low complexity approach is only about 14%, while the complexity of the algorithm is greatly reduced. Manuscript profile -
Open Access Article
6 - Better Performance of New Generation of Digital Video Broadcasting-terrestrial (DVB-T2) Using Alamouti scheme with Cyclic Delay Diversity
Behnam Akbarian Saeed Ghazi-MaghrebiThe goal of the future terrestrial digital video broadcasting (DVB-T) standard is to employ diversity and spatial multiplexing in order to achieve the fully multiple-input multiple-output (MIMO) channel capacity. The DVB-T2 standard targets an improved system performanc MoreThe goal of the future terrestrial digital video broadcasting (DVB-T) standard is to employ diversity and spatial multiplexing in order to achieve the fully multiple-input multiple-output (MIMO) channel capacity. The DVB-T2 standard targets an improved system performance throughput by at least 30% over the DVB-T. The DVB-T2 enhances the performance using improved coding methods, modulation techniques and multiple antenna technologies. After a brief presentation of the antenna diversity technique and its properties, we introduce the fact of the well-known Alamouti decoding scheme cannot be simply used over the frequency selective channels. In other words, the Alamouti Space-Frequency coding in DVB-T2 provides additional diversity. However, the performance degrades in highly frequency-selective channels, because the channel frequency response is not necessarily flat over the entire Alamouti block code. The objective of this work is to present an enhanced Alamouti space frequency block decoding scheme for MIMO and orthogonal frequency-division multiplexing (OFDM) systems using the delay diversity techniques over highly frequency selective channels. Also, we investigate the properties of the proposed scheme over different channels. Specifically, we show that the Alamouti scheme with using Cyclic Delay Diversity (CDD) over some particular channels has the better performance. Then, we exemplarity implement this scheme to the DVB-T2 system. Simulation results confirm that the proposed scheme has lower bit error rate (BER), especially for high SNRs, with respect to the standard Alamouti decoder over highly frequency-selective channels such as single frequency networks (SFN). Furthermore, the new scheme allows a high reliability and tolerability. The other advantages of the proposed method are its simplicity, flexibility and standard compatibility with respect to the conventional methods. Manuscript profile -
Open Access Article
7 - Complexity Reduction in Massive-MIMO-NOMA SIC Receiver in Presence of Imperfect CSI
Nilufar Tutunchi Afrooz Haghbin Behrad MahboobiOne of the main reasons for switching to the next generation of communication systems is the demand of increasing capacity and network connections. This goal can be achieved using massive multiple input - multiple output (massive-MIMO) systems in combination with Non-or MoreOne of the main reasons for switching to the next generation of communication systems is the demand of increasing capacity and network connections. This goal can be achieved using massive multiple input - multiple output (massive-MIMO) systems in combination with Non-orthogonal multiple access (NOMA) technique. NOMA technology uses the successive interference cancellation (SIC) receiver to detect user’s signals which imposes an additional complexity on the system. In this paper, we proposed two methods to reduce the system complexity. The proposed method despite imperfect channel state information (CSI) in the receiver, there is not significantly reduction in the system performance. Since the computation of matrices inverse has a high computational complexity, we used the Neumann series approximation method and the Gauss-Seidel decomposition method to compute matrices inverse in the SIC receiver. Simulation results are provided at the end of the paper in terms of bit error rate (BER) at the receiver which show, these methods have lower computational complexity in comparison with the traditional methods while they cause a slight performance reduction in the SIC receiver. Also, we examined the increasing and decreasing value of imperfect channel state information in the system performance which shows the increasing value of imperfect channel state information, cause a slight performance reduction in SIC receiver. Manuscript profile -
Open Access Article
8 - Optical Power Distributions for 4×4 MIMO Visible Light Communications in Indoor Environment
lwaa abdulameer Ahmed Hassan Aliaa T. Obeed Aya N. DahirVisible Light Communication (VLC) has emerged as a powerful technique for wireless communication systems. Providing high data rate and increasing capacity are the major problems in VLC. Recent evidence suggests that Multiple Input Multiple Output (MIMO) technique can of MoreVisible Light Communication (VLC) has emerged as a powerful technique for wireless communication systems. Providing high data rate and increasing capacity are the major problems in VLC. Recent evidence suggests that Multiple Input Multiple Output (MIMO) technique can offers improved data rates and increased link range. This paper describes the design and implementation of visible light communication system in indoor environment exploring the benefits of MIMO. The specific objective of this research was to implement a 4×4 Multiple Input (LEDs) Multiple Output (photodetectors)-VLC communication system, where a 16 white power LEDs in four arrays are setting up at transmitter and four RX modules are setting up at receiver side without the need for additional power or bandwidth as well as analyze a mathematical model for a VLC- 4×4 MIMO with different modes such as the suitable angles to cover the entire room. The research designs practically an electronic circuit for the transmitter and receiver with inexpensive components. The power distribution of different propagation modes is calculated for Single Input Single Output (SISO) and MIMO channels in typical room dimensions. The results in this paper indicate that the power is distributed uniformly for entire room when implemented VLC-MIMO as compared to VLC-SISO. Furthermore, a 4×4 MIMO implementing VLC is compared in term of BER vs. SINR with SISO communication system for both Line of Sight (LOS) and Non Line of Sight (NLOS) propagation modes. Comparing the two results of LOS and NLOS, it can be seen that a 4×4 MIMO implementing VLC for LOS perform better than the same system with NLOS due to decreasing in the received power resulted from the multipath effect. Manuscript profile -
Open Access Article
9 - Low Complex Standard Conformable Transceiver based on Doppler Spread for DVB-T2 Systems
Saeed Ghazi-Maghrebi Behnam AkbarianThis paper addresses a novel Alamouti space-frequency block decoding scheme with discontinuous Doppler diversity (DDoD) and cyclic delay diversity (CDD). We investigate different antenna diversity concepts, which can be applied to orthogonal frequency division multiplex MoreThis paper addresses a novel Alamouti space-frequency block decoding scheme with discontinuous Doppler diversity (DDoD) and cyclic delay diversity (CDD). We investigate different antenna diversity concepts, which can be applied to orthogonal frequency division multiplexing (OFDM) systems over highly frequency selective channels. The main object of this research is standard compatibility and the effect of simple diversity techniques on the channel fading properties. Therefore, we analyze a receiver in terms of the effective channel transfer function, which leads to the possibility of optimizing diversity. Besides, a novel transceiver using DDoD is proposed, which increases the Doppler spread of the multipath fading channel without causing additional Intercarrier Interference (ICI). Moreover, an efficient Alamouti encoder and decoder based on CDD is proposed, which allows a high reliability and capacity enhancement. In order to evaluate the capability of that, we have implemented this scheme for the second-generation terrestrial video broadcasting (DVB-T2) system over different channels. Furthermore, mathematical analysis and simulation results show the bit error performance of the modified encoding method with these diversity techniques, performs mostly better than the other forms of encoding Alamouti over highly frequency-selective channels such as single frequency networks (SFN). The other advantages of the proposed method are simplicity, flexibility, and standard compatibility. Manuscript profile -
Open Access Article
10 - Low-Complexity Iterative Detection for Uplink Multiuser Large-Scale MIMO
Mojtaba Amiri Mahmoud Ferdosizade NaeinyIn massive Multiple Input Multiple Output (MIMO) or large scale MIMO systems, uplink detection at the Base Station (BS) is a challenging problem due to significant increase of the dimensions in comparison to ordinary MIMO systems. In this letter, a novel iterative metho MoreIn massive Multiple Input Multiple Output (MIMO) or large scale MIMO systems, uplink detection at the Base Station (BS) is a challenging problem due to significant increase of the dimensions in comparison to ordinary MIMO systems. In this letter, a novel iterative method is proposed for detection of the transmitted symbols in uplink multiuser massive MIMO systems. Linear detection algorithms such as minimum-mean-square-error (MMSE) and zero-forcing (ZF), are able to achieve the performance of the near optimal detector, when the number of base station (BS) antennas is enough high. But the complexity of linear detectors in Massive MIMO systems is high due to the necessity of the calculation of the inverse of a large dimension matrix. In this paper, we address the problem of reducing the complexity of the MMSE detector for massive MIMO systems. The proposed method is based on Gram Schmidt algorithm, which improves the convergence speed and also provides better error rate than the alternative methods. It will be shown that the complexity order is reduced from O(〖n_t〗^3) to O(〖n_t〗^2), where n_t is the number of users. The proposed method avoids the direct computation of matrix inversion. Simulation results show that the proposed method improves the convergence speed and also it achieves the performance of MMSE detector with considerable lower computational complexity. Manuscript profile -
Open Access Article
11 - A New Power Control Algorithm in MMSE Receiver for D2D Underlying Massive MIMO System
Faezeh Heydari Saeed Ghazi-Maghrebi Ali Shahzadi Mohammad Jalal Rastegar FatemiDevice to device (D2D) underlying massive MIMO cellular network is a robust deployment which enables network to enhance its throughput. It also improves services and applications for the proximity-based wireless communication. However, an important challenge in such dep MoreDevice to device (D2D) underlying massive MIMO cellular network is a robust deployment which enables network to enhance its throughput. It also improves services and applications for the proximity-based wireless communication. However, an important challenge in such deployment is mutual interference. Interference, in the uplink spectrum, reusing the same resource with cellular user, is caused by D2D users. In this paper, we study a distributed power control (DPC) algorithm, using minimum mean square error (MMSE) filter in receiver, to mitigate the produced interference in this deployment scenario. For the DPC algorithm, employing the coverage probability of D2D links, an optimal power control approach is proposed, which maximizes the spectral efficiency of D2D links. Using this modeling approach, it is possible to derive closed-form analytical expressions for the coverage probabilities and ergodic spectral efficiency, which give insight into how the various network parameters interact and affect the link. Also, the DPC algorithm is modeled by stochastic geometry and receiver filter is designed by estimation theory that a new structure in this robust network is an approach to improve spectral efficiency. Simulation results illustrate enhancing coverage probability performance of D2D links in term of the target (signal to interference ratio) SIR with respect to different receiver filter and other parameters which are existing in D2D links. Manuscript profile -
Open Access Article
12 - SQP-based Power Allocation Strategy for Target Tracking in MIMO Radar Network with Widely Separated Antennas
Mohammad Akhondi Darzikolaei Mohammad Reza Karami-Mollaei Maryam NajimiMIMO radar with widely separated antennas enhances detection and estimation resolution by utilizing the diversity of the propagation path. Each antenna of this type of radar can steer its beam independently towards any direction as an independent transmitter. However, t MoreMIMO radar with widely separated antennas enhances detection and estimation resolution by utilizing the diversity of the propagation path. Each antenna of this type of radar can steer its beam independently towards any direction as an independent transmitter. However, the joint processing of signals for transmission and reception differs this radar from the multistatic radar. There are many resource optimization problems which improve the performance of MIMO radar. But power allocation is one of the most interesting resource optimization problems. The power allocation finds an optimum strategy to assign power to transmit antennas with the aim of minimizing the target tracking errors under specified transmit power constraints. In this study, the performance of power allocation for target tracking in MIMO radar with widely separated antennas is investigated. Therefore, a MIMO radar with distributed antennas is configured and a target motion model using the constant velocity (CV) method is modeled. Then Joint Cramer Rao bound (CRB) for target parameters (joint target position and velocity) estimation error is calculated. This is utilized as a power allocation problem objective function. Since the proposed power allocation problem is nonconvex. Therefore, a SQP-based power allocation algorithm is proposed to solve it. In simulation results, the performance of the proposed algorithm in various conditions such as a different number of antennas and antenna geometry configurations is examined. Results affirm the accuracy of the proposed algorithm. Manuscript profile -
Open Access Article
13 - Maximum Likelihood Detection in MIMO Communication Systems in Presence of Channel Estimation Error
M. biguesh A. A. farhoodi m.a. masnadi shiraziCapacity of wireless communication systems can be increased significantly by using arrays of antenna at the transmitter and receiver. In these so called multiple input multiple output (MIMO) communication systems, the algorithms used for detection of transmitted symbols MoreCapacity of wireless communication systems can be increased significantly by using arrays of antenna at the transmitter and receiver. In these so called multiple input multiple output (MIMO) communication systems, the algorithms used for detection of transmitted symbols are based on perfect channel state information (CSI) at the receiver side. The optimum detection approach in the sense of symbol error rate (SER) is Maximum likelihood (ML) detector. However, in the case of imperfect channel knowledge, the performance of this type of detection method degrades and symbol error rate (SER) increases. In this manuscript, we have briefly addressed the effect of imperfect channel knowledge on the performance of MIMO communication systems. Then, an analytical approach is proposed to cope with the destructive effect of CSI uncertainty on the ML detection algorithm and the performance of our proposed method is verified via computer simulations. Manuscript profile -
Open Access Article
14 - A Geometric Model for MIMO Channel with Distributed of Scatterers between the Base Station and the User
F. Zadeh-Parizi M. Mehrjoo J. ahmadi-ShokouhThe paper presents a geometry-based MIMO channel model for outdoor-to-indoor applications. The propagation channel model is derived when indoor scatterers are located on a hollow-disk around the user and a distribution of outdoor scatterers exists between the base stati MoreThe paper presents a geometry-based MIMO channel model for outdoor-to-indoor applications. The propagation channel model is derived when indoor scatterers are located on a hollow-disk around the user and a distribution of outdoor scatterers exists between the base station and the user. The closed-form Cross-Correlation Function (CCF) is derived for the aforementioned scenario. This function depends on various parameters of interest including the distance between the base station and the user, the spacing among antennas elements, and the directions of the antennas elements. The numerical CCF values are obtained with Radiowave Propagation Simulator (RPS) software for the building of Electrical and Computer Engineering School at the University of Sistan and Baluchestan. The results show that considering the outdoor scatterers increases the accuracy of the CCF and the capacity computation significantly. Manuscript profile -
Open Access Article
15 - High Rate Shared Secret Key Generation Using the Phase Estimation of MIMO Fading Channel and Multilevel Quantization
V. Zeinali Fathabadi H. Khaleghi Bizaki A. ShahzadiMuch attention has recently been paid to methods of shared secret key generation that exploit the random characteristics of the amplitude and phase of a received signal and common channel symmetry in wireless communication systems. Protocols based on the phase of a rece MoreMuch attention has recently been paid to methods of shared secret key generation that exploit the random characteristics of the amplitude and phase of a received signal and common channel symmetry in wireless communication systems. Protocols based on the phase of a received signal, due to the uniform distribution phase of fading channel, are suitable in both static and dynamic environments and, they have a key generation rate (KGR) higher than protocols based on received signal strength (RSS).In addition, previous works have generally focused on key generation protocol for single-antenna (SISO) systems but these have not produced a significant KGR. So in this paper to increase the randomness and key generation rate are used received signal phase estimations on multiple-antenna (MIMO) systems because they have the potential to present more random variables in key generation compared to SISO systems. The results of simulation show that the KGR of the proposed protocol is 4 and 9 times more than the KGR of a SISO system, when the numbers of transmitter and receiver antennas are the same and equal to 2 and 3, respectively. Also, the key generation rate will increase considerably, when to extract the secret key bits using multilevel quantization. Manuscript profile -
Open Access Article
16 - Designing an Applicable MIMO DC-DC Converter with Multivariable Controller for SMES System
M. R. Alizadeh Pahlavani S. Taghipour BroujeniIn modern power systems, utilization of renewable energy sources makes some difficulties for the power grid. One of these problems is shortage of electrical power during conditions which renewable energy sources cannot generate electrical power. For example, during shad MoreIn modern power systems, utilization of renewable energy sources makes some difficulties for the power grid. One of these problems is shortage of electrical power during conditions which renewable energy sources cannot generate electrical power. For example, during shading conditions, the output power of the PV array is negligible. Using SMES (Superconducting Magnetic Energy Storage) systems is one of the applicable solutions which has been proposed to solve mentioned problem. In SMES system, energy is stored at high power inductances and during critical conditions; this power can be delivered to the load. One of the important parts of SMES systems is Multi input - Multi Output (MIMO) DC-DC converter. In this paper, at first step, one topology has been designed for the MIMO DC-DC converter. This topology has remarkable advantages such as fewer electrical elements and better controllability than other topologies. In the second part of this paper, based on multivariable controller strategy, an efficient controller has been designed for the SMES system which can set the output voltages of DC-DC converter at predetermined values. The most important feature of proposed controller is its efficiency at different conditions which some of these conditions make serious problems for conventional controllers. Generally, the objective of this paper is designing one SMES systems with an appropriate controller, which can regulate the output voltages at different conditions. Manuscript profile -
Open Access Article
17 - Covariance Matrix Design for SINR Enhancement in Presence of Signal-Dependent Interferers
M. Bolhasani S. Imani S. A. GhorashiIn this paper, the problem of covariance matrix design to increase signal-to-interference-plus-noise ratio (SINR) in receiver for multiple-input multiple-output (MIMO) radars is considered. Our goal is to design a covariance matrix which can suppress more interferers co MoreIn this paper, the problem of covariance matrix design to increase signal-to-interference-plus-noise ratio (SINR) in receiver for multiple-input multiple-output (MIMO) radars is considered. Our goal is to design a covariance matrix which can suppress more interferers compared to phased array radar and recent covariance matrix design methods. It can also result in a better SINR level compared to conventional MIMO radars. In this paper, maximum SINR of the proposed covariance matrix is calculated in closed form. Simulation results show that our proposed covariance matrix in addition to achieve better SINR performance, can suppress more interferers compared to phased array radar and recent covariance matrix design methods, by using waveform diversity with the same number of antennas. Simulation results also validate analytical achievements that presented in this paper. Manuscript profile -
Open Access Article
18 - A New Statistical-Physical UTD Based Channel Model for Calculating Channel Capacity in Mobile Urban Areas
Ali TajvidyIn urban areas, wireless communications suffer from severe fading due to reflections and diffraction of waves from buildings and mobility of receivers. Hence, in design of wireless networks, we need a model to predict propagation channels, in order to determine communic MoreIn urban areas, wireless communications suffer from severe fading due to reflections and diffraction of waves from buildings and mobility of receivers. Hence, in design of wireless networks, we need a model to predict propagation channels, in order to determine communication methods between transmitters and receivers. Most of current mobile wireless communication models are based on measurements. In this paper, we want to introduce a new statistical physical model in which buildings are considered as a fixed part of the model and the phenomena of diffraction and reflection are modeled using the uniform theory of diffraction (UTD).On the other hand, the receiver in this model is considered as a car. The position of this car is predicted using the Poisson point process (PPP). We can predict channel capacity in urban areas, taking into account the density of traffic and urban traffic by using this model. Furthermore, in order to validate the proposed model, we compared the results of this model with a statistical model based on measurements and there is a good agreement between them. Manuscript profile -
Open Access Article
19 - Advanced Spatial Modulation
A. Abbasfar H. TafreshianIn this paper, we present a new scheme named advanced spatial modulation for multiple input multiple output (MIMO) systems. Advanced spatial modulation achieves more spectral efficiency than ordinary spatial modulation with using power divider and set the phase of activ MoreIn this paper, we present a new scheme named advanced spatial modulation for multiple input multiple output (MIMO) systems. Advanced spatial modulation achieves more spectral efficiency than ordinary spatial modulation with using power divider and set the phase of active transmit antennas. Using Power divider enable us to have more than one active antenna in a time slot with only one RF-chain in transmitter. Additionally, we can allocate more spatial bits with map information bits into the phase of the transmit antenna. Then, the performance of the proposed system is simulated and is compared with ordinary spatial modulation and some MIMO techniques such as orthogonal space time block code and V-BLAST. Manuscript profile -
Open Access Article
20 - Space Time Code Design in Phased-MIMO Radars to Achieve High Resolution in Board and Velocity
Roholah Vahdani Hossein Khaleghi Mohsen Fallah JoshaghaniIn this paper, space-time codes for MIMO radar are used to achieve high resolution at target range and speed. The two-dimensional ambiguity function is known as a tool to compare radar performance in terms of resolution. A space-time code can be designed based on minimi MoreIn this paper, space-time codes for MIMO radar are used to achieve high resolution at target range and speed. The two-dimensional ambiguity function is known as a tool to compare radar performance in terms of resolution. A space-time code can be designed based on minimizing the distance between the actual target parameters in range, speed and angle. For this purpose, high resolution can be achieved by analyzing the ambiguity function and narrowing it down as much as possible. In this paper, the ambiguity function with two variables of amplitude and speed mismatch is considered and a new criterion to achieve high resolution performance in this field is proposed. In this case, by optimizing the proposed cost functions, the optimal space-time code is extracted. The proposed design can also be extended to phased-MIMO radar. The simulation results also show that our proposed scheme has a very narrow ambiguity function around the origin, while it has a performance very close to the optimal state in terms of target identification probability. Manuscript profile -
Open Access Article
21 - Hybrid Beamforming in MIMO Systems via Matrix Decomposition
MIMO systems, and particularly massive MIMO systems, achieve high spectral efficiency by using a large number of antennas. An important issue in these systems is beamforming. In fully digital baseband beamforming, an RF chain is required for each antenna, which leads to MoreMIMO systems, and particularly massive MIMO systems, achieve high spectral efficiency by using a large number of antennas. An important issue in these systems is beamforming. In fully digital baseband beamforming, an RF chain is required for each antenna, which leads to high cost and power consumption. In analog beamforming, only one RF chain is used and beamforming is performed by using phase shifters. This method does not provide optimal spectral efficiency and thus, analog-digital hybrid methods for beamforming are considered. In this paper, a hybrid beamforming method is proposed in which the required number of RF chains is much less than fully digital method. The precoder and receiver filter are designed by maximizing the spectral efficiency. To this end, the optimal beamforming matrix (which contains the right singular vectors of the channel matrix) is approximated by the product of two analog and digital beamforming matrices. This approximation is improved by an iterative method. The criterion for the proximity of the two matrices is considered to be the Frobenius norm of their differences. In the receiver, the design of the hybrid beamforming is performed in a similar way, using the mean squares error criterion. Also, to improve the method, a gradient-based algorithm is proposed to further reduce the error. The simulation results show the performance superiority of the proposed method over similar methods as well as its less complexity. Manuscript profile -
Open Access Article
22 - Detector Design & Power Allocation of Frequency Diverse Phased Multi Input Multi Output Radar within Nonhomogeneous Environments
Hamid Reza Fotoohi Firouzabad Seyed Mehdi Hosseini Andargoli Hossein Ghanei Yakhdan J. AboueiIn recent years, Phased-Multiple-Input, Multiple-Output radars (PMRs) have attracted great interest. PMR can combine the advantages of both MIMO radar and phased array radar. Here, PMR transmits orthogonal signals from all subarrays to provide both waveform frequency di MoreIn recent years, Phased-Multiple-Input, Multiple-Output radars (PMRs) have attracted great interest. PMR can combine the advantages of both MIMO radar and phased array radar. Here, PMR transmits orthogonal signals from all subarrays to provide both waveform frequency diversity and high coherent processing gain. In this paper dealt with detector design in the presence of heterogeneous clutter based on the unknown scattering coefficients for PMR. Then, detection probability and false-alarm probability are computed based on the derived optimum detector. At the end, the power allocation problem is investigated analytically. The numerical simulations show that obtained optimal detector is joint spatial-temporal filter, which, the clutters are effectively weakened in PMR. Furthermore, simulation results illustrate that proposed power allocation algorithm improve detection performance of PMR in comparison with PR and equal power PMR. Manuscript profile -
Open Access Article
23 - A Novel Detector based on Compressive Sensing for Uplink Massive MIMO Systems
Mojtaba Amiri Amir AkhavanMassive multiple-input multiple-output is a promising technology in future communication networks where a large number of antennas are used. It provides huge advantages to the future communication systems in data rate, the quality of services, energy efficiency, and spe MoreMassive multiple-input multiple-output is a promising technology in future communication networks where a large number of antennas are used. It provides huge advantages to the future communication systems in data rate, the quality of services, energy efficiency, and spectral efficiency. Linear detection algorithms can achieve a near-optimal performance in large-scale MIMO systems, due to the asymptotic orthogonal channel property. But, the performance of linear MIMO detectors degrades when the number of transmit antennas is close to the number of receive antennas (loaded scenario). Therefore, this paper proposes a series of detectors for large MIMO systems, which is capable of achieving promising performance in loaded scenarios. The main idea is to improve the performance of the detector by finding the hidden sparsity in the residual error of the received signal. At the first step, the conventional MIMO model is converted into the sparse model via the symbol error vector obtained from a linear detector. With the aid of the compressive sensing methods, the incorrectly detected symbols are recovered and performance improvement in the detector output is obtained. Different sparse recovery algorithms have been considered to reconstruct the sparse error signal. This study reveals that error recovery by imposing sparse constraint would decrease the bit error rate of the MIMO detector. Simulation results show that the iteratively reweighted least squares method achieves the best performance among other sparse recovery methods. Manuscript profile -
Open Access Article
24 - A New Power Allocation Optimization for One Target Tracking in Widely Separated MIMO Radar
Mohammad Akhondi Darzikolaei Mohammad Reza Karami-Mollaei Maryam NajimiIn this paper, a new power allocation scheme for one target tracking in MIMO radar with widely dispersed antennas is designed. This kind of radar applies multiple antennas which are deployed widely dispersed from each other. Therefore, a target is observed simultaneousl MoreIn this paper, a new power allocation scheme for one target tracking in MIMO radar with widely dispersed antennas is designed. This kind of radar applies multiple antennas which are deployed widely dispersed from each other. Therefore, a target is observed simultaneously from different uncorrelated angles and it offers spatial diversity. In this radar, a target’s radar cross section (RCS) is different in each transmit-receive path. So, a random complex Gaussian RCS is supposed for one target. Power allocation is used to allocate the optimum power to each transmit antenna and avoid illuminating the extra power in the environment and hiding it from interception. This manuscript aims to minimize the target tracking error with constraints on total transmit power and the power of each transmit antenna. For calculation of target tracking error, the joint Cramer Rao bound for a target velocity and position is computed and this is assumed as an objective function of the problem. It should be noted that a target RCS is also considered as unknown parameter and it is estimated along with target parameters. This makes a problem more similar to real conditions. After the investigation of the problem convexity, the problem is solved by particle swarm optimization (PSO) and sequential quadratic programming (SQP) algorithms. Then, various scenarios are simulated to evaluate the proposed scheme. The simulation results validate the accuracy and the effectiveness of the power allocation structure for target tracking in MIMO radar with widely separated antennas. Manuscript profile -
Open Access Article
25 - Three Dimensional Beamforming in Multi User Multi Antenna Cellular Networks with Randomly Distributed Users
S. Mohammad Razavizadeh Nasim MohammadiIn this paper, problem of using the 3D beamforming method (3DBF) in a multi-input-multi-output cellular communication network (MIMO) is discussed. The network consists of a cell with multiple users, in which users are distributed based on the Poisson point (PPP) process MoreIn this paper, problem of using the 3D beamforming method (3DBF) in a multi-input-multi-output cellular communication network (MIMO) is discussed. The network consists of a cell with multiple users, in which users are distributed based on the Poisson point (PPP) process at the cell area, which is closer to the conditions in a real mobile network. In this case, the number of users inside the cell and their location will be random. Depending on the distribution of users in the space and the difference in their distance from the base station, their elevation angles will also be different. Considering the downlink transmission and the zero-forcing (ZF) precoder in the base station, with the aim of eliminating intra cell interference, we evaluate and analyze the probability of coverage in the cell and then we obtain the best antenna tilt angle to achieve maximum probability of coverage. Using the analysis of numerical results, the accuracy of the calculations and the value of the optimal tilt angle of the antenna array are confirmed. Manuscript profile -
Open Access Article
26 - Power Efficient allocation in C-RAN with Multi access technology selection approach
ALI ASGHAR ANSARI Mohsen Eslami Mohammad Javad Dehghani Saeideh Parsaei Fard: In this paper, we consider an uplink economy-efficient resource allocation in a multicellular virtual wireless network with a C-RAN architecture where a MNO interacts with a number of MVNOs with a predetermined business model. In each cell of this system, two types of More: In this paper, we consider an uplink economy-efficient resource allocation in a multicellular virtual wireless network with a C-RAN architecture where a MNO interacts with a number of MVNOs with a predetermined business model. In each cell of this system, two types of multiple access technologies, namely OFDMA and Massive MIMO, are available for MVNO at two different prices. In this setup, we propose a multi access technology selection approach (MATSA) with the objective to reduce operating costs and maximize the profit of the MVNOs subject to a set of constraints, and formulate this resource allocation problem with the new utility function. Due to the existence of continuous and binary variables in the formulated optimization problem and also the interference between cells in data rate functions, this optimization problem will be non-convex with very high computational complexity. To tackle this problem, by applying the complementary geometric programming (CGP) and the successive convex approximation (SCA), an effective two-step iterative algorithm is developed to convert the optimization problem into two sub problems with the aim to find optimum technology selection and power consumption parameters for each user in two steps, respectively. The simulation results demonstrate that our proposed approach (MATSA) with novel utility function is more efficient than the traditional approach, in terms of increasing total EE and reducing total power consumption. The simulation results illustrate that the profit of the MVNOs is enhanced more than 13% compared to that of the traditional approach. Manuscript profile
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