JOURNAL OF COMMUNICATION ENGINEERING
Year:2018 | Volume:7 | Issue:2|Papers Count:10

In this paper, the problem of target detection in phased-MIMO radars is considered and target detection performance of phased-MIMO radars is compared with MIMO and phased-array radars. Phased-MIMO radars combine advantages of the MIMO and phased-array radars. In these radars, the transmit array will be partitioned into a number of subarrays that are allowed to overlap and each subarray transmits a waveform which is orthogonal to the waveform transmitted by other subarrays. In this paper, target detection performance of phased-MIMO radars is analyzed with two detectors theoretically in addition to the investigation of simulation results. First, it is assumed that the transmitted waveforms are ideally orthogonal and secondly the transmitted waveforms are considered to be correlated (not fully coherent or ideally orthogonal). The Generalized likelihood ratio test (GLRT) and the likelihood ratio test (LRT) are used for target detection. The closed-form expressions of the false alarm and detection probabilities in presence of Gaussian noise are obtained. Simulation results validate the theoretical analysis.

Due to the prevalence of Wireless Sensor Networks (WSNs) in the many mission-critical applications such as military areas, security has been considered as one of the essential parameters in Quality of Service (QoS), and Intrusion Detection System (IDS) is considered as a fundamental requirement for security in these networks. This paper presents a lightweight Intrusion Detection System to protect the WSNs against the most important of routing attacks in network layer based on their extracted specifications. The proposed IDS, in contrast to related works that often focuses on a specific attack, covers almost all recognized important routing attacks in WSNs. With the full simulation of the routing attacks and the careful examination of their behavior, we extracted key specifications to identify them in the proposed system. Also, due to local operations provided to detect and significantly reduce communications, the proposed method is a lightweight approach. Another advantage of the proposed method is reducing false alarms rate by applying appropriate thresholds. We considered all performance criteria to evaluate and compare the proposed method. Simulation results show that the proposed system is an effective and lightweight IDS in WSNs due to high detection accuracy, low false alarms rate, and low power consumption.

Tracking a target which is sensed by a collection of randomly deployed, limited-capacity, and short-ranged sensors is a tricky problem and, yet applicable to the empirical world. In this paper, this challenge has been addressed by introducing a nested algorithm to track a maneuvering target entering the sensor field. In the proposed nested algorithm, different modules are to fulfil different functions, including sensor selection, adaptive maneuver parameter estimation, and target trajectory extraction. To that end, proposed algorithm combines the auxiliary particle filter with the Liu and West filter and applies them for the first time in the wireless sensor network. Its performance is compared to one of the most common approaches for this kind of problem and the results show the superiority of proposed method in terms of the estimation accuracy. The simulation study also involves evaluating the proposed algorithm based on the scalability criterion and the results are promising since the reduction by 40 percent in the number of active sensors leads to, respectively, 18. 2 and 14. 3 percent increments in the RMSE of position and velocity estimates.

An analytical technique is proposed for estimation of the radiation pattern of inverted-F antenna (IFA) which is mounted on the side wall of a long cylinder. The method can be applied to describe the IFA radiation in a lot of practical cases. It is indicated that this radiation pattern is a combination of radiation patterns of a horizontal and a vertical small radiator, near the cylinder with a certain proportion. Some discussion is presented about this proportion and analytical results are compared with the simulations. Also the proportion is formulated in terms of antenna dimensions using a GA optimization. Finally a typical applicable IFA with smooth radiation pattern is fabricated and its radiation pattern is measured to verify the proposed method. The proposed method can help the designer to estimate the radiation pattern of IFA antenna that mounted on a big cylinder quickly before the simulation.

Polar codes, that have been recently introduced by Arikan, are one of the first codes that achieved the capacity for vast numerous channels and they also have low complexity in symmetric memoryless channels. Polar codes are constructed based on a phenomenon called channel polarization. This paper discusses relay channel polarization in order to achieve the capacity and show that if inputs of two different relay channels follow the Arikan polarization structure, then they will be categorized as good and bad relay channels. Also, it has been shown that the eencoding and decoding complexity for these codes is O(N logN ), N is the code-length, and their error probability is O(2 (N ) )   like the Arikan's work, β is a number between [0, 0. 5]. In order to validate our construction of polar codes for relay channels, some numerical examples for this idea have been presented. Also, the efficiency of this construction for decode-and-forward and compressand-forward relaying strategies have been analyzed by using simulation results for finite block length in relay channels with orthogonal receiver.

Due to lack of resources such as transmission power and bandwidth in satellite systems, resource allocation problem is a very important challenge. Nowadays, new heterogeneous network includes one or more satellites besides terrestrial infrastructure, so that it is considered that each satellite has multi-beam to increase capacity. This type of structure is suitable for a new generation of communications, which leads to a specific benefit of using the available resource in wireless communication systems. The multi-beam technology is one of the multiple access methods for new satellite systems that are similar to very high throughput satellites systems. Therefore, in this paper, our proposed algorithm is mainly the jointly power and bandwidth allocation of satellite systems to each beam and it is simulated considering the limitation of the total transmission power and bandwidth constraints for any beams. Furthermore, a bandwidth sharing algorithm is provided to dedicate extra bandwidth among beams. Finally, the total capacity of our proposed system model, which is heterogeneous network is obtained based on some parameters such as frequency reuse, modulation rate and total number of users for each beam. This comparison shows that the proposed algorithm allows maintaining the optimal capacity allocation to use a new satellite network.

The aim of this paper is to fully analyze the effects of free space optical (FSO) communication links on the estimation performance of the adaptive incremental networks. The FSO links in this paper are described with two turbulence models namely the Log-normal and Gamma-Gamma distributions. In order to investigate the impact of these models we produced the link coefficients using these distributions and assumed that the network is exchanging data between the nodes that are contaminated with these coefficients. Firstly, by the FSO link assumption, we performed the theoretical analysis for the steady-state performance of the adaptive network and driven closed-form relations explaining the link impacts. Secondly, we performed simulation results for Log-normal and Gamma-Gamma link conditions and presented various results for different levels of turbulence. Finally, we compared the theoretical and analytical results showing a close agreement between these two findings. The results are presented by the means of mean square deviation (MSD) and excess mean square error (EMSE) values.

In this paper, a systematic method for the design of circuit parameters of a monolithic LC Voltage Controlled Oscillator (VCO) is reported. The method is based on the negative resistance generation technique. As a result, a VCO has been designed in 0. 18um CMOS technology using a conventional VCO structure to obtain the optimum values for the phase noise and power consumption. The simulation results prove that the proposed approach is very reliable and can be developed further for more complex structures. In this paper, the minimum phase noise of-110. 94 dBc/Hz has been obtained at 1 MHz offset frequency at the operating frequency of 10. 67 GHz. Furthermore, the designed VCO has the low power consumption of 1. 8 mW at the fundamental frequency. In addition, the designed VCO has 1280 MHz of tuning range from 9. 39 GHz to 10. 67 GHz around the central frequency of 10 GHz. Other than that, the maximum output power of the signal in the designed VCO is 6. 24 dBm.

In this paper, using adaptive networks-based fuzzy inference systems (ANFIS), a comprehensive closed-form solution for effective length of vertical grounding rod is extracted in such a way that the two effects of ionization and dispersion are simultaneously considered. In creating the model, training data are computed from multi-conductor transmission line (MTL). As a result, via ANFIS the effective length in such soils is efficiently computed. The simulation results show that considering both effects results in a length which is greater than the one in only-dispersive soil, and less than the one in only-ionized soil. Such a result is financially very important.

Advances in low-power electronics design and wireless communication have enabled the development of low cost, low power micro-sensor nodes. These sensor nodes are capable of sensing, processing and forwarding which have many applications such as underwater networks. In underwater wireless sensor networks (UWSNs) applications, sensors which are placed in underwater environments and predicted enable applications in oceanographic data collection, mine reconnaissance, pollution, assisted navigation, distributed tactical surveillance, and ocean sampling. Each sensor uses acoustic signals as its physical medium for communications. This study focuses on a priority-based routing protocol in underwater wireless sensor networks. This routing method tries to improve the QOS requirements with considering high and low priority traffic classes. Through simulation study using the OPNET simulator, we proved that proposed algorithm achieves high performance as compared to GEDAR, in terms of packet loss, end to end delay of data transmission and energy consumption.