Journal of Communication Engineering
Volume:9 Issue: 1, Winter-Spring 2020

Abstract—This work proposes a novel congestion management protocol for constrained delay traffic and optimized rate control for HWSNs. The proposed protocol consists of congestion avoidance and control. We distinguish between high and low priority traffics which are serviced upon their priority and QoS requirements. For high priority traffic, we control end to end delay constrains with node output scheduling weights. For low priority traffics firstly we avoid congestion using a new Active Queue Management (AQM) algorithm that uses distinct virtual queue's situation for a single physical queue in order to decide accepting or dropping the received packets from child nodes. If acceptance occurs for the incoming packet, congestion is detected by the proposed protocol using a three-state machine as well as a virtual queue status. Afterward, child’s sending rate is adjusted using an optimization function. Results of simulation indicate goal achievement for the protocol proposed.

A multi-band stepped-slot antenna, fed by modified 50 Ω coplanar waveguide (CPW) transmission line is described and implemented. The designed antenna effectively supports digital communication systems (DCS 1.71–1.88GHz), personal communication systems (PCS 1.85–1.99 GHz), worldwide interoperability for microwave access (WiMAX 3.30–3.80GHz), forth generation (4G 3.40–4.2 GHz) mobile communication system, and wireless local area network (WLAN 5.15– 5.35 GHz). In order to cover the aforementioned valuable bands, in the first step rectangular slots are subtracted symmetrically from the radiating patch. Besides, stair-shaped rectangular slots are etched at the radiator edges. Also, to operate at DCS and PCS systems, dual-section CPW feed line with different widths is designed. Actually antenna is designed by using quasi-fractal methods, to cover frequency ranges of 1.64– 1.99 GHz, 3.35–4.3 GHz and 4.8–5.4 GHz (for |S11|< −10 dB). The antenna size is 75.2 × 38.54 × 1.6 mm3 and it is etched on FR4 substrate. The antenna development steps are presented and discussed in detail. Moreover investigation of important design parameters is performed. The designed multi-band antenna has respectable results such high gain in center of each operating band and considerable efficiency of 90 %, 85% and 86% in 1.85, 4 and 5GHz respectively. Also omni-directional patterns and acceptable group delay are obtained. Measurement data are presented to validate the numerical outcomes. All of these prominent features make this antenna, worthwhile for multi-band applications.

One of the major against in Wireless Sensor Networks (WSNs) is wormhole so that two or more attacker nodes help each other to rob communications and record the information in another place. Wormhole attacks can disrupt communications, change routing, or cause some other localization errors. This attack can also bring about physical access without permission, cause package losses, and increase traffic in the network. Attacker nodes can convince ordinary sensor nodes that they are neighbors and can observe their information and any other traffic that they send in the link length. Localization is an important problem in WSNs. DV-Hop (Distance Vector-hop) is a traditional algorithm for localizing sensor nodes using a hop distance assessment. The DV-Hop model has poor localization accuracy. This paper improves DV-Hop and increases wormhole attack detection accuracy in WSNs based on localization method. In this paper, a new distance based on correction of Hop-size and gap measurement is proposed to minimize the error that exists in DV-Hop. The results of simulation and assessment show that the proposed model carry outs better than DV-Hop in different topologies, in which proposed model has significantly higher localization accuracy.

In this paper, a miniaturized and broadband 4 × 4 Butler matrix is presented. All components of the presented matrix are designed in a way that, have the broadband impedance bandwidth and compact electrical size as much as possible. Traditional previous Butler matrix composed of phase shifters, while in the presented feeding network dummy crossover role this act, which results to enhance the phase difference bandwidth. The compactness of the optimized and proposed coupler is related to inserting the S-shaped arms instead of ordinary parts. The modified dummy crossover is used to overcome the mismatch phase difference among phase shifter and crossover. Design procedure of miniaturized broadband components such as 3-branch-line coupler, crossover, phase shifter and final design are presented step by step. The results of the simulation and measurement of the desired Butler matrix makes it suitable for the applications of planar multi-beam antennas. The extracted results determine that the bandwidth of the presented network is from 4.5 ~ 6 GHz, that is a good candidate for WLAN applications. The whole size of network is 71.5 × 38.3 mm2.

Wireless sensor network (WSN) comprises various distributed nodes that are physically separated. Nodes are constantly applying for sensing their environment. If the information sensitivity coefficient is very high, data should be conveyed continually and also with confidentially. WSNs have many vulnerability features because of data transferring on the open air, self-organization without reformed structure, bounded range of sources and memory, and limited computing capabilities. Therefore, the implementation of security protocols in WSN is inescapable. According to the resemblance between WSN and biotic reaction to the real menace in nature, bio-inspired approaches have variant rules in computer network investigations. In this paper, we exploited an ant colony optimization (ACO) algorithm based on Ad-hoc On-Demand Distance Vector (AODV) protocol for detection of black hole attacks. Finally, the Grover quantum metaheuristic algorithm is applied to optimize attack paths detection. The results gained from extensive simulations in WSN proved that the proposed approach is capable of improving some fundamental network parameters such as throughput, end-to-end delay, and packet delivery ratio in comparison with other approaches.

Surface integral equation formulations of periodic structures have received attention because of the inherent efficiency of surface unknowns and automatic satisfaction of radiation condition through the problem's Green's function. These formulations employ the periodic Green's function (PGF); the addition of potentials from all point sources as observed in the unit cell. Unfortunately, the resulting series (1) has slow convergence when direct summation (DS) is employed, which makes its usage in MoM codes rather costly. In this paper a new closed form is derived for efficient computation of the linear one-dimensional and planar (two-dimensional) periodic Green’s function at small source to observation points' distances. When combined with an accelerated modal (Floquet-wave) expression for more distant observation points, an efficient form is obtained for all distances. The efficiency of the proposed formulations have been shown through numerical computation.

The provision of proper routing methods in wireless sensor networks is important due to the sensors' limited hardware and software resources. Some important metrics should be achieved with the use of an efficient routing algorithm, such as low packet loss, improved quality of service, and low energy consumption. Clustering-based routing algorithms have a more efficient performance in the case of link breakages, compared to the other table-based methods. Therefore, a new clustering-based routing algorithm is proposed in this paper that takes the sensors' energy limitation into consideration. The proposed method is designed based on a three-step fuzzy logic. The steps are used to determine the cluster head node and to discover and select a suitable route. In the proposed fuzzy system, the best selection is done based on the existing real-time information. Simulation results show that the proposed method results in a 7% reduction in the network energy consumption simultaneous with a higher packet delivery ratio up to 4% in comparison with IDACB, as the basic algorithm.

This paper presents a novel solution of two dimensional (2-D) method of moments (MoM) in Cartezian coordination to calculate the source-type electric field integral equations (EFIE) arising from electromagnetic inverse scattering problems in microwave imaging (MI). The main issue is to reduce the 2-D problem into 1-D case, using decomposition the electric-type Green’s function of inhomogeneous media. In this regard, recursive formulas in spatial frequency domain are derived for both TE and TM problems and the scattering field is rewritten into upward and downward components in a recursive form. It helps us to calculate a 2-D problem using 1-D stabilized biconjugate-gradient fast Fourier transform (BCGSFFT) of the induced source and save lots of memory and time for inhomogeneous objects in MI performance. The paper provides 2-D TM and TE scattering examples for different scenarios and compares the proposed and conventional algorithms to demonstrate merits of the proposed formulas in terms of the accuracy and computational efficiency.

In this paper, the fabrication of a bulk current injection (BCI) probe using two different ferrite materials and a wideband rounded-shield calibration fixture or jig used to calibrate BCI probe are presented. Some optimization ideas are also investigated to increase their performance. The effect of change in various parameters such as slot distance, probe’s shield to probe’s core spacing and the inner surface of probe’s shield on the probe high frequency performance and insertion loss (IL) have been studied. Results show that increasing the slot distance improves the high frequency response of the probe and increasing the probe’s shield to probe’s core spacing would affect negatively on measured IL and decreasing the inner surface of probe’s shield improves the probe working bandwidth.

An ultra-wideband thin metasurface is designed and fabricated to reduce the radar cross-section (RCS) from 9.72 GHz to 26.77 GHz (93 % bandwidth) more than 10 dB. The proposed metasurface is composed of two different artificial magnetic conductor (AMC) tiles with about 180° reflection phase differences to destruct the reflected wave over ultra-wideband frequency. Although the designed tiles have similar unit cell configuration, their reflected phase responses are properly tuned by changing the dimensions. The comparison between the proposed AMC metasurface and some sate of the art references clearly proves the high RCS reduction bandwidth with very low thickness of the designed AMC metasurface rather than the references. The measured results are in good agreement with the simulation ones which prove the idea.

Fountain codes are erasure codes that are characterized by their rateless property and their global acknowledgment. The larger the network size, the more efficient the fountain codes are degraded because of multi-hops causing an overflow. The optimization of wireless communication is also a focus of study exciting and an important issue always to maximize performance, the lifetime of the sensor nodes, and to reduce the consumption of energy. Estimation becomes one of the attractive topics in wireless sensor networks nowadays. In this paper, I consider a distributed estimation scheme composing of a sensor member and a fusion center, which is the cluster head. To minimize the number of transmissions as well as the impact of overflow, I determine the optimal minimal number of encoded packets needed for successful decoding. Sensor observations are encoded using fountain codes, and then messages are collected at the cluster head where a final estimation is provided with a classification based on Bayes rule. The main goal of this paper is to estimate the total number of received packets using the Bayes rule so that it is possible to minimize the overflow and extend the network lifetime.

A new multi-band planar inverted-F antenna (PIFA) is presented for wireless applications‎. ‎PIFA is‎ ‎designed in two stages‎. ‎First‎, ‎the antenna consists of a radiating plate injected with a slot and it is shorted to ground plane with two shorting walls‎. ‎The structure covers three bands‎. ‎A small and narrow slot on the ground plane is embedded to afford increasing the bandwidths of the antenna at the resonance frequencies and improve radiation patterns at the second resonance frequency‎, ‎thereby giving a more omnidirectional pattern‎. ‎Second‎, ‎a parasitic element is used at the antenna to design a quad-band PIFA antenna‎. ‎Moreover‎, ‎an L-shaped slot is embedded on the radiating plate to improve the reflection coefficient at the third resonance frequency‎. ‎The antenna is optimized to operate at 1.1 GHz‎, ‎2.4 GHz‎, ‎3.6 GHz and 5.3 GHz bands‎. ‎It can be used both indoor and outdoor wireless video‎, ‎wireless cameras and wireless security applications at the 1.1 GHz band‎, ‎Bluetooth‎, ‎Wi-Fi and Wireless Local Area Network (WLAN) at the 2.42 GHz band‎, ‎Microwave Access (m-WiMAX) at the 3.6 GHz band‎, ‎and WLAN at the 5.3 GHz‎ . ‎The antenna is simulated and fed through a coaxial cable connected to the feeding strip; then it is fabricated and measured‎. ‎The total antenna volume of the proposed design is 90×42×7.5 mm2‎.