List of subject articles Communication Systems & Devices


    • 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 Haghbin
      This 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 Full Text
      This 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 Document
    • Open Access Article

      2 - Improving Accuracy, Area and Speed of Approximate Floating-Point Multiplication Using Carry Prediction
      Marziye Fathi Hooman Nikmehr
      The arithmetic units are the most essential in digital circuits’ construct, and the enhancement of their operation would optimize the whole digital system. Among them, multipliers are the most important operational units, used in a wide range of digital systems such as Full Text
      The arithmetic units are the most essential in digital circuits’ construct, and the enhancement of their operation would optimize the whole digital system. Among them, multipliers are the most important operational units, used in a wide range of digital systems such as telecommunication signal processing, embedded systems and mobile. The main drawback of a multiplication unit is its high computational load, which leads to considerable power consumption and silicon area. This also reduces the speed that negatively affects the digital host functionality. Estimating arithmetic is a new branch of computer arithmetic implemented by discarding or manipulating a portion of arithmetic circuits and/or intermediate computations. Applying estimated arithmetic in arithmetic units would improve the speed, power consumption and the implementation area by sacrificing a slight amount of result accuracy. An estimated truncated floating-point multiplier for single precision operands which is capable of compensating the errors to a desired level by applying the least significant columns of the partial product matrix is developed and analyzed in this article. These errors are caused by removing a number of carry digits in the partial product matrix that have a direct contribution in rounding the floating-point numbers. The evaluation results indicate that the proposed method improves speed, accuracy and silicon area in comparison to those of the common truncated multiplication methods. Manuscript Document
    • Open Access Article

      3 - A Novel Resource Allocation Algorithm for Heterogeneous Cooperative Cognitive Radio Networks
      Mehdi Ghamari Adian
      In cognitive radio networks (CRN), resources available for use are usually very limited. This is generally because of the tight constraints by which the CRN operate. Of all the constraints, the most critical one is the level of permissible interference to the primary us Full Text
      In cognitive radio networks (CRN), resources available for use are usually very limited. This is generally because of the tight constraints by which the CRN operate. Of all the constraints, the most critical one is the level of permissible interference to the primary users (PUs). Attempts to mitigate the limiting effects of this constraint, thus achieving higher productivity is a current research focus and in this work, cooperative diversity is investigated as a promising solution for this problem. Cooperative diversity has the capability to achieve diversity gain for wireless networks. Thus, in this work, the possibility of and mechanism for achieving greater utility for the CRN when cooperative diversity is incorporated are studied carefully. To accomplish this, a resource allocation (RA) model is developed and analyzed for the heterogeneous, cooperative CRN. In the considered model, during cooperation, a best relay is selected to assist the secondary users (SUs) that have poor channel conditions. Overall, the cooperation makes it feasible for virtually all the SUs to improve their transmission rates while still causing minimal harm to the PUs. The results show a remarkable improvement in the RA performance of the CRN when cooperation is employed in contrast to when the CRN operates only by direct communication. Manuscript Document
    • Open Access Article

      4 - Good Index Choosing for Polarized Relay Channel
      hassan Tavakoli saeid Pakravan
      The Polar coding is a method which have been proposed by Arikan and it is one of the first codes that achieve the capacity for vast numerous channels. This paper discusses relay channel polarization in order to achieve the capacity and it has been shown that polarizatio Full Text
      The Polar coding is a method which have been proposed by Arikan and it is one of the first codes that achieve the capacity for vast numerous channels. This paper discusses relay channel polarization in order to achieve the capacity and it has been shown that polarization of two relay channels can be given a more achievable rate region in the general form. This method is compatible with the original vision of polarization based on the combining, splitting and polarizing of channels and it has been shown that the complexity of encoding and decoding for these codes in mentioned method are O(N log⁡〖N)〗, and also error probability for them is O(2^(〖-(N)〗^β )). Choose the best sub-channels in polarized relay channels for sending data is a big trouble in this structure. In this paper, we have been presented a new scheme for choosing a good index for sending the information bits in relay channels polarized in order to have the best performance by using sending information bits over FIF sets. Manuscript Document
    • Open Access Article

      5 - Better performance of special triangular constellations for the OFDM systems in complicated fading channel
      saeed ghazi-maghrebi
      Due to high spectral efficiency, immunity to frequency selective fading, and high data rate, OFDM became a popular modulation technique in digital communication systems. Effectiveness of a signal constellation used in a communication system can provide a fundamental bas Full Text
      Due to high spectral efficiency, immunity to frequency selective fading, and high data rate, OFDM became a popular modulation technique in digital communication systems. Effectiveness of a signal constellation used in a communication system can provide a fundamental basis for efficiency of application networks. During recent years, different constellations were designed for different modulation schemes. In this research, two new triangular constellations schemes which are named as TRI1 and TRI2 are introduced to replace for the well-known rectangular QAM constellation in OFDM modulation. In this paper, the new proposed schemes are compared with different triangular constellations. It has been shown that these new schemes have three major advantages with respect to the QAM. The first advantage is its lower BER which results from the better usage of the constellation space with longer minimum distances. The second advantage of these schemes is their lower PAR with respect to the rectangular QAM constellation. The third property, as the last advantages, is their higher noise immunity with respect to the commonly used QAM constellation. Both mathematical analysis and simulation results demonstrate that by applying high fading channels with AWGN and ISI impairment simultaneously, the TRI1 and TRI2 exhibit a superior performance compared to the rectangular QAM. As a result, they are good choice for high speed and real-time multicarrier applications such as DAB, DVB, and WiFi at no extra cost. Manuscript Document
    • Open Access Article

      6 - A Survey of Two Dominant Low Power and Long Range Communication Technologies
      Yas Hosseini Tehrani Seyed Mojtaba Atarodi ZIba Fazel
      The Internet of Things (IoT) connects various kinds of things such as physical devices, vehicles, home appliances, etc. to each other enabling them to exchange data. The IoT also allows objects to be sensed or controlled remotely and results in improved efficiency, accu Full Text
      The Internet of Things (IoT) connects various kinds of things such as physical devices, vehicles, home appliances, etc. to each other enabling them to exchange data. The IoT also allows objects to be sensed or controlled remotely and results in improved efficiency, accuracy and economic benefits. Therefore, the number of connected devices through IoT is increasing rapidly. Machina Research estimates that the IoT will consist of about 2.6 billion objects by 2020. Different network technologies have been developed to provide connectivity of this large number of devices, like WiFi for cellular-based connections, ZigBee and Bluetooth for indoor connections and Low Power Wide Area Network's (LPWAN) for low power long-distance connections. LPWAN may be used as a private network, or may also be a service offered by a third party, allowing companies to deploy it without investing in gateway technology. Two available leading technologies for LPWAN are narrow-band systems and wide-band plus coding gain systems. In the first one, receiver bandwidth is scaled down to reduce noise seen by the receiver, while in the second one, coding gain is added to the higher rate signal to combat the high receiver noise in a wideband receiver. Both LoRa and NB-IoT standards were developed to improve security, power efficiency, and interoperability for IoT devices. They support bidirectional communication, and both are designed to scale well, from a few devices to millions of devices. LoRa operates in low frequencies, particularly in an unlicensed spectrum, which avoids additional subscription costs in comparison to NB-IoT, but has lower Quality of Service. NB-IoT is designed to function in a 200kHz carrier re-farmed from GSM, with the additional advantage of being able to operate in a shared spectrum with an existing LTE network. But in the other hand, it has lower battery lifetime and capacity. This paper is a survey on both systems. The review includes an in-depth study of their essential parameters such as battery lifetime, capacity, cost, QoS, latency, reliability, and range and presents a comprehensive comparison between them. This paper reviews created testbeds of recent researches over both systems to compare and verify their performance. Manuscript Document
    • Open Access Article

      7 - Polar Split Tree as a Search Tool in Telecommunication
      فرزاد بیات زهرا نیلفروشان
      Tree search algorithms are vital for the search methods in structured data. Such algorithms deal with nodes which can be taken from a data structure. One famous tree data structure is split tree. In this paper, to compute the split tree in polar coordinates, a method ha Full Text
      Tree search algorithms are vital for the search methods in structured data. Such algorithms deal with nodes which can be taken from a data structure. One famous tree data structure is split tree. In this paper, to compute the split tree in polar coordinates, a method has been introduced. Assuming that the algorithm inputs (in form of points) have been distributed in the form of a circle or part of a circle, polar split tree can be used. For instance, we can use these types of trees to transmit radio and telecommunication waves from host stations to the receivers and to search the receivers. Since we are dealing with data points that are approximately circular distributed, it is suggested to use polar coordinates. Furthermore, there are several researches by search algorithms for the central anchor which leads to the assignment of a virtual polar coordinate system. In this paper, the structure of Cartesian split tree will be explained and the polar split tree will be implemented. Then, by doing nearest neighbor search experiments, we will compare the polar split tree and polar quad tree in terms of searching time and amount of distance to the closest neighbor and in the end, better results will be achieved. Manuscript Document
    • Open Access Article

      8 - A Novel Approach for Cluster Self-Optimization Using Big Data Analytics
      Abbas Mirzaei Amir Rahimi
      One of the current challenges in providing high bitrate services in next generation mobile networks is limitation of available resources. The goal of proposing a self-optimization model is to maximize the network efficiency and increase the quality of services provided Full Text
      One of the current challenges in providing high bitrate services in next generation mobile networks is limitation of available resources. The goal of proposing a self-optimization model is to maximize the network efficiency and increase the quality of services provided to femto-cell users, considering the limited resources in radio access networks. The basis for our proposed scheme is to introduce a self-optimization model based on neighbouring relations. Using this model, we can create the possibility of controlling resources and neighbouring parameters without the need of human manipulation and only based on the network’s intelligence. To increase the model efficiency, we applied the big data technique for analyzing data and increasing the accuracy of the decision-making process in a way that on the uplink, the sent data by users is to be analyzed in self-optimization engine. The experimental results show that despite the tremendous volume of the analyzed data – which is hundreds of times bigger than usual methods – it is possible to improve the KPIs, such as throughput, up to 30 percent by optimal resource allocation and reducing the signaling load. Also, the presence of feature extraction and parameter selection modules will reduce the response time of the self-optimization model up to 25 percent when the number of parameters is too high Moreover, numerical results indicate the superiority of using support vector machine (SVM) learning algorithm. It improves the accuracy level of decision making based on the rule-based expert system. Finally, uplink quality improvement and 15-percent increment of the coverage area under satisfied SINR conditions can be considered as outcome of the proposed scheme. Manuscript Document
    • Open Access Article

      9 - A Bias-reduced Solution for Target Localization with Distance-dependent Noises in Illuminator of Opportunity Passive Radar
      حبیب راثی Maryam Shirzadian Gilan
      A closed-form solution for target localization based on the realistic distance-dependent noises in illuminator of opportunity passive radar and the reduction method of the bias which exists in the two-stage weighted least squares (2SWLS) method is proposed. 2SWLS is a c Full Text
      A closed-form solution for target localization based on the realistic distance-dependent noises in illuminator of opportunity passive radar and the reduction method of the bias which exists in the two-stage weighted least squares (2SWLS) method is proposed. 2SWLS is a classic method for time-of-arrival (TOA) and frequency-of-arrival (FOA) localization problem and has a couple of improved solutions over the years. The 2SWLS and its improved solutions have great localization performances in their established location scenarios on the basis of two approximations that setting the noise to a constant and ignoring the high-order terms of TOA and FOA measurement noises. It is these two approximations that lead to a sub-optimal solution with bias. The bias of 2SWLS has a significant influence on the target localization in illuminator of opportunity passive radar that has lower measurement accuracy and higher noises than active radar. Therefore, this paper starts by taking into consideration of the realistic distance-dependent characteristics of TOA/-FOA noises and improving 2SWLS method. Then, the bias of the improved 2SWLS method is analyzed and bias-reduced solution based on weighted least squares (WLS) is developed. Numerical simulations demonstrate that, compared to the existing improved solutions of the 2SWLS, the proposed method effectively reduces the bias and achieves higher localization accuracy. Manuscript Document
    • Open Access Article

      10 - A New Capacity Theorem for the Gaussian Channel with Two-sided Input and Noise Dependent State Information
      Nima S. Anzabi-Nezhad Ghosheh  Abed Hodtani
      Gaussian interference known at the transmitter can be fully canceled in a Gaussian communication channel employing dirty paper coding, as Costa shows, when interference is independent of the channel noise and when the channel input designed independently of the interfer Full Text
      Gaussian interference known at the transmitter can be fully canceled in a Gaussian communication channel employing dirty paper coding, as Costa shows, when interference is independent of the channel noise and when the channel input designed independently of the interference. In this paper, a new and general version of the Gaussian channel in presence of two-sided state information correlated to the channel input and noise is considered. Determining a general achievable rate for the channel and obtaining the capacity in a non-limiting case, we try to analyze and solve the Gaussian version of the Cover-Chiang theorem mathematically and information-theoretically. Our capacity theorem, while including all previous theorems as its special cases, explains situations that can not be analyzed by them; for example, the effect of the correlation between the side information and the channel input on the capacity of the channel that can not be analyzed with Costa’s “writing on dirty paper" theorem. Meanwhile, we try to exemplify the concept of “cognition" of the transmitter or the receiver on a variable (here, the channel noise) with the information-theoretic concept of “side information" correlated to that variable and known at the transmitter or at the receiver. According to our theorem, the channel capacity is an increasing function of the mutual information of the side information and the channel noise. Manuscript Document
    • Open Access Article

      11 - Optical Power Distributions for 4×4 MIMO Visible Light Communications in Indoor Environment
      lwaa abdulameer Ahmed Hassan Aliaa T. Obeed Aya N. Dahir
      Visible 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 Full Text
      Visible 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 Document
    • Open Access Article

      12 - Low Complex Standard Conformable Transceiver based on Doppler Spread for DVB-T2 Systems
      Saeed Ghazi-Maghrebi Behnam Akbarian
      This 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 Full Text
      This 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 Document