Network IEEE Research Articles

Analysis of the efficiency of block frame transmission in IEEE 802.11 computer networks

In infrastructure schemes of WLANs wireless computer networks, which are based on the use of the DSF (distributed coordination function) function and the CSMA/CA mechanism, the station STA (STAtion) sends a frame if the transmission channel is released after waiting for the end of the DIFS (distributed interframe space) interval and operation of the slot selec-tion mechanism for transmission (backoff mechanism). In case of collisions or damage to the frame by interference, the AP cannot decode the frame and does not send it back to the ACS station. The sending station STA waits for the re-ceipt of a potential ASK before the expiration of the corresponding timeout, and in case of receipt, starts the backoff procedure before transmission. The duration of the slot used in the backoff process depends on the speed of the physical layer technology. To reduce overhead, a transmission mechanism using frame blocks was proposed. This mechanism assumes that a block of frames intended for one recipient can be sent without con-firming the fact of correct reception by the AP access point of each frame separately. In this case, the sender (STA) competes for access to the channel for the first frame of the block. If it wins the access competition, the transmission of the first frame begins, and after receiving the ACK acknowledgment for it and a short SIFS separation interval, the STA transmits a whole block of frames, which is accompanied by a BAR service frame. The mechanism of frames block transmission in wireless computer networks IEEE 802.11 DCF with infrastructure topology has been analyzed. In protected mode, the depend-encies of network throughput on data transmission rate and the number of frames in a block are determined. It is shown that the mechanism of block transmission significantly increases the network throughput, especially in the range of higher transmission rates. With a marked increase in the intensity of interference the transmission of blocks becomes more complicated. Already with BER=10^-6 and the frames number of the order of 10 and more, in some cases there is a need to retransmit distorted in a block frames, and at BER=10^-5 there are many re-transmissions, so the resulting network throughput becomes small.

A miniaturized ultra-wideband filter with high rejection and selectivity based on dual-notch bands.

A novel compact and highly selective Ultra Wide Band (UWB) filter is proposed using multimode resonator (MMR) technology. To begin with, the filter's ultra-wideband performance is achieved by coupling a stepped-triangular multimode resonator with input-output feedlines. Furthermore, dual-notch band characteristics are realized at 6.80 GHz and 9.82 GHz, employing asymmetric coupled lines and the split ring resonator (SRR) methods. Eventually, by using a Defected Ground Structure (DGS), the filter's correct transmission zero is deepened, further enhancing the out-of-band suppression performance at higher frequencies. The measured results are in excellent agreement with the experimental results, and the filter has a passband range of 3.52-11.68 GHz, a center frequency of 7.59 GHz, an insertion loss of just 0.61 dB, and a return loss of more than 18 dB. The transmission zeros have a rejection capability of more than 47 dB attenuation, and the rectangular coefficient of the filter is 1.34, which is outstanding for filtering out the interference signals in the parasitic passband with superior selectivity. The overall structure is compact, and the size is just 0.41λg×0.20λg. The filter can be used for UWB system filtering and also to avoid interference from some Wireless Local Area Network (WLAN) IEEE 802.11 series and x-band satellite link frequency bands.

Optimized planning framework of solar photovoltaic based generation with EV charging station in a rural distribution network considering uncertainties

To address the adverse impacts due to rapid growth of electric vehicles (EVs), a robust planning framework is developed in this paper for optimal deployment of EV charging stations and solar energy resources in the distribution network. Uncertainty modeling of EV is done using probability density function considering stochastic parameters extracted from real National Household Travel Survey (NHTS)datasheet. Considering solar irradiance as the uncertainty parameter, a practical Photovoltaic (PV) model is developed using beta probability function. To solve the problem of optimal allocation of EV charging stations and PV in the distribution network, proposed Teaching Learning Based Optimization algorithm is used. The problem is formulated to minimize the power loss reduction index and the voltage deviation index while considering system constraints. Here this proposed approach is tested to Indian 28 bus rural distribution network and standard IEEE 69 bus system in MATLAB. Also to assess the efficiency of the proposed technique, it is compared with three different algorithms, i.e., Genetic Algorithm (GA), Particle Swarm Optimization (PSO) and Differential Evolution (DE) in terms of convergence characteristics and computational time. The system indices, i.e., voltage profile, line loss, voltage stability and the penetration level of EV charging station are improved after simultaneously optimally deploying EV charging station and PV units both in rural and standard 69 bus distribution networks. Different case studies were conducted and it was observed that deployment of EV charging station in the network leads to deterioration of voltage profile, voltage stability and line loss. The simulation outcome further reveals that the addition of PV panels concurrently with EV charging stations enhances the system performances and the penetration level of EV charging station in the network.

Behavior of prosumers in Smart Grid: A comparison of Net Energy Metering and Billing Schemes, and Game Theory-based Local Electricity Market

Net energy metering (NEM) and net energy billing (NEB) are the most commonly used self-consumption schemes for prosumers in countries around the world. The concept of the local electricity market (LEM) is emerging as the potential successor of the self-consumption schemes, with several already implemented pilot projects. The comparative study of prosumers’ behavior in terms of optimal economic self-dispatching under NEM, NEB, and game-theory-based LEM energy policies is performed in this paper. The non-cooperative game-theoretic methodology is used for the calculation of Nash–Cournot equilibrium which is adopted as an LEM clearing mechanism. The prosumers’ daily energy patterns (generation, consumption, and storage) and payoffs are analyzed. Diversities of prosumers’ assets (distributed energy resources (DERs) and storage devices) and load profiles are considered. The distribution utility’s role is considered in terms of its own payoff for supplying the necessary energy to ensure the power balance equation. The numerical analysis is performed using the model of the benchmark test distribution network IEEE 33-node. The obtained results are discussed in terms of the correlation between prosumers’ behavior and the adopted energy policy. The strengths and weaknesses of the most common energy policies are highlighted from the prosumers’ perspective. The obtained results confirm that the transition from NEM to NEB self-consumption scheme could provide a better payoff to prosumers with dispatchable DERs under variable electricity price for excess energy produced. The residential prosumers equipped with SDs or dispatchable DERs were able to achieve the best payoffs in the case of Game Theory-based LEM.

Optimal operation of multi-agent electricity-heat-hydrogen sharing in integrated energy system based on Nash bargaining

The P2P transaction mode has significant potential in improving energy utilization, increasing economic efficiency, and promoting low carbon operation of the system. With the development of integrated energy system, the coupling between multi-energy systems is continuously strengthened, and the study of multi-energy P2P transactions is of great significance. Considering the characteristic that natural gas can blend with hydrogen, this paper proposes a multi-agent electricity-heat-hydrogen trading model by taking hydrogen produced on the load side as a P2P transaction object. Based on Nash bargaining theory, the multi-energy transactions model is equivalent to a cooperative game model. Then, the Nash bargaining model is transformed into two continuous subproblems of minimizing operating cost and maximizing transaction payment. The optimal cost of each agent operating independently is used as the negotiation rupture point, and the alternating direction multiplier method is used for sequential solution to obtain the multi-energy trading power and trading price, respectively. Finally, the effectiveness of the proposed method is verified by using the distribution network IEEE 33-bus and natural gas 11 node systems. The results show that the revenue of subject 1 is increased by 11.9%, and the operating costs of the other subjects are reduced by 3.4%, 2.7% and 3.1%, respectively. The overall carbon tax cost of the system is reduced by 1 196.59 CNY, which can effectively reduce the carbon emission of the system.

Utilization of dynamic wireless power transfer technology in multi-depot, multi-product delivery supply chain

Dynamic wireless charging technology (DWC) is considered an innovative contactless way to charge the battery of electric vehicles (EV) in the modern transportation system. By installing charging infrastructure beneath the road, this technology can overcome the obstacles of conventional charging topology, including high battery cost, restricted driving range, limited availability of charging stations, and long recharging downtime. This paper proposes a long-term mathematical model for locating-routing electric freight trucks (EFTs), which belongs to the Multi-Depot Multi-product delivery supply chain. In the proposed framework, the placement of DWC infrastructure and routing of EFTs has been accomplished by considering the battery capacity of trucks, charging facilities installation cost, electrical energy losses, and the voltage deviation in the power distribution system (PDS). Finally, two comparative case studies have been performed on the interconnected network IEEE 13 node test feeder and Nguyen–Dupius traffic network to validate the proposed approach. We also conduct a sensitivity analysis to understand the model’s system behavior and confirm it with insight.

Design and optimisation of high‐efficient class‐F ULP‐PA using envelope tracking supply bias control for long‐range low power wireless local area network IEEE 802.11ah standard using 65 nm CMOS technology

This article presents the design and optimisation of a sub-1 GHz class-F ultra-low power (ULP) power amplifier (PA) in 65 nm Complementary Metal Oxide Semiconductor (CMOS) technology. An envelope tracking (ET) supply biasing technique is adopted to improve the efficiency of class-F PA. The ET consist of a pre-amp right before the detector in order to enhance the efficiency and save adequate amount of dc power consumption. The PA consists of two cascode cells terminated as class-F with gate-to-drain feedback in order to enhance linearity and limit any harmonic component from the input signal. The novel design consumes a dc power of 3.75 mW, power added efficiency of 37.1%, operating at 915–925 MHz unlicensed band and total saturated output power of 22 dBm including 14 dBm power gain at PA, which qualifies under long-range low power wireless personal area network IEEE 802.11ah standard. The inductor-less design for ET supply bias reduces the chip layout size to 0.13 mm2 only.

A CPW fed quad-port MIMO DRA for sub-6 GHz 5G applications

The present work investigates a novel four-port, multiple-input multiple-output (MIMO), single element dielectric resonator antenna (DRA) for sub-6 GHz band. The DRA is designed and fabricated into a symmetric cross shape and fed using a coplanar waveguide (CPW) feed. A single radiator with four ports is rarely found in the literature. The -10 dB impedance bandwidth covered by the antenna is from 5.52 GHz to 6.2 GHz (11.6%) which covers fifth generation (5G) new radio (NR) bands N47 and wireless local area network (WLAN) IEEE 802.11a band. The isolation between orthogonal ports is about 15 dB while the isolation between opposite ports is 12 dB. The radiation pattern of the proposed antenna is bidirectional due to the absence of a ground plane below the DRA. The orthogonal modes excited in the DRA are and through the four symmetrical CPW feeds. The simulated and measured results of the proposed design show that MIMO characteristics are achieved by pattern diversity between the ports. Due to the perfect symmetry of the design, the proposed work could be extended to MIMO array applications as well.

Evaluation of Flying Ad Hoc Network Topologies, Mobility Models, and IEEE Standards for Different Video Applications

Nowadays, drones became very popular with the enhancement of the technological progress of moving devices with a connection to each other, known as Flying Ad Hoc Network (FANET). It is used in most worldwide necessary life scenarios such as video recording, search and rescue, military missions, moving items between different areas, and many more. This leads to the necessity to evaluate different network strategies between these flying drones, which are essential to improve their quality of performance in the field. Several challenges must be addressed to effectively use FANET, to provide stable and reliable transmission for different types of data during vast changing topologies, such as different video sizes, different types of mobility models, recent Wireless Fidelity standards, types of routing protocols used, security problems, and many more. In this paper, a fully comprehensive analysis of FANET will be done to evaluate and enhance these challenges that concern different video types, mobility models, and IEEE 802.11n standards for best performance, by measuring throughput, retransmission attempt, and delay metrics. The result shows that Gauss–Markov mobility model gives the highest result using Ad Hoc On-Demand Vector and lowest delay, whereas for retransmission attempts, 2.4 GHz frequency has the lowest as it can reach more coverage area than 5 GHz.

Genetic Algorithm Applied to Planning IEEE 802.11g Networks

The problem of planning local wireless network IEEE 802.11g consists of automatically positioning and setting up wireless access points (APs) in order to provide access to the local network with the desired coverage and the required quality of service (QOS).In addition to the complexity of predicting the Quality of Service (QoS) of a network from the variables of the problem (positions, parameters and frequency of the APs), the planning of WLAN networks faces several difficulties. In particular, the location of APs and the allocation of frequencies. There is no single model to solve the problem of designing wireless local networks. Depending on the situations and the hypotheses studied, different criteria can be considered and expressed in terms of constraints to be observed or in terms of objectives to be optimized. The first distinction is to separate the financial criteria from the network quality criteria. The nature of these two criteria being fundamentally different. Then there are a variety of service quality criteria, but we can still group them into three main categories: coverage criteria, interference criteria and capacity criteria.. In this article, we will use an optimization method based on an algorithm of stochastic optimization, which is also based on the mechanisms of natural selection and of genetic. It is genetic algorithm. Our goal consist of minimizing the total interaction between the APs to perform the good choices when deploying a network 802.11g in a way that gives users signal-to-interference ratios (SIR) greater than the required threshold ß.

Enabling Device‐to‐Device (D2D) Communication for the Next Generation WLAN

Device‐to‐device (D2D) communication technology is widely acknowledged as an emerging candidate to alleviate the wireless traffic explosion problem for the next generation wireless local area network (WLAN) IEEE 802.11ax. In this paper, we integrate D2D communication into IEEE 802.11ax for maximizing the spectrum efficiency. Due to the spectrum scarcity, the number of available resource units (RUs) is typically less than D2D pairs and stations (STAs), which makes the management of spectrum resources more complex. To tackle this issue, we design an efficient resource management algorithm for uplink random access and resource allocation in D2D‐enabled 802.11ax, which provides more channel access and resource reuse opportunities for STAs and D2D pairs. Specifically, we propose an enhanced back‐off mechanism and derive the optimal contention window (CW) by a theoretical model, which improves the uplink random access efficiency. To tackle the complex interference problem in RU scheduling phase, we develop an efficient and low‐complexity resource allocation algorithm based on the maximal independent set (MIS), which can schedule multiple D2D pairs to share the same RU with the specific STA. Simulation results demonstrate that the proposed algorithm significantly improves the network performance in terms of system throughput, collision rate, complete time, and channel utilization.

FD-OMAC: A Novel Full-Duplex Optical Media Access Control for IEEE 802.15.7

Optical wireless communication (OWC), the IEEE 802.15.7 standard (revised 2018) is developed in normative reference to low-rate wireless personal area networks IEEE 802.15.4 standard. One significant difference between the two standards is the highly directional transmitters in the OWC networks. This difference opens up the possibility of adding full-duplex communication to wireless networks. Our work proposes adding full-duplex functionality in the contention-free period (CFP) of the OWC media access control (MAC) layer. We justify the significance of our proposal by implementing IEEE 802.15.7 resource allocation scheme for both our proposed full-duplex optical MAC (FD-OMAC) and the IEEE 802.15.7 MAC. Our simulation results demonstrate that the proposed work improves the spectral efficiency in the CFP without compromising delays. We also discuss the minor changes required in the IEEE 802.15.7 MAC for implementing FD-OMAC. We further extend the FD-OMAC to a multiple access point network and evaluate its performance in comparison with IEEE 802.15.7 MAC.

Distribution systems techno-economic performance optimization through renewable energy resources integration

Abstract This article presents three new multi-objective optimization methodologies as a solution for enhancing the traditional EDN techno-economic performance through integrating Distributed Generation (DG) of different categories. A combination of four types of DG resources is presented for identifying the optimal mix sizing and positioning through applying the Whale Optimization Algorithm, Sine Cosine Algorithm and Multi-Verse Optimization Algorithm. The proposed approaches are constructed and subjected to a multi-objective function to minimize the active power losses, improve the voltage Stability and decrease overall additional costs. While taking into consideration the allowable margin of DG units’ penetration level and their operating power factor in addition to the systems’ voltage profile boundaries. The methodologies have been applied to two IEEE benchmark test systems (33-bus and 118-bus) besides a realistic part of the distribution grid of the Egyptian distribution network which is added as a practical case study. However, the proposed base cases have failed in keeping the voltage magnitudes boundaries at all busbars especially the realistic case, but the proposed algorithms have attained almost the same significant results regarding both of voltage stability and power loss for the medium-sized network IEEE 33-bus system. Furthermore, for both of the two large scale systems (IEEE 118-bus system and the realistic network), the MVO has proved its superiority compared to the proposed algorithms in addressing the optimization problem with higher results’ accuracy. Meanwhile, the MVO has reached the optimal solutions for all cases in less time and iterations number.

A Guo‐shaped patch antenna for hidden WLAN access points

This research communication introduces a Chinese-character artistic antenna, wherein a Guo-shaped patch antenna is devised for circular-polarization applications. The novelty is emphasized by Guo-shaped patch printed in standard SimHei font at the antenna's front end. The artistic patch antenna is singly-fed and cavity-backed by a metallic-box reflector to enhance the forward directivity (~7dBic) and the front-to-back radiation ratio (~20 dB). The Guo-shaped patch exhibits an axial-ratio bandwidth of 120 MHz that covers the 2.4 GHz band of wireless local-area network (WLAN) IEEE 802.11b/g/n/ax. The proposed antenna owns an overall dimension of 1λo × 1λo × 0.11λo at 2.5 GHz. ©2018 Wiley Periodicals, Inc. Int J RF and Microwave.

PROBABILISTIC CHARACTERISTICS OF WIRELESS NETWORKS WITH INFRASTRUCTURE TOPOLOGY

Based on the analysis of the operation of networks IEEE 802.11 DCF, a function is proposed for determining the probability of frame transmission to a central node depending on the number of stations operating in saturation mode. The probabilities of collisions are calculated. Using a polynomial approximations an expression is obtained for the network throughput, which explicitly depends on the number of the simultaneously operating stations.

Multiple BSSs Association Based Spatial Clustering Group Access Protocol for Next Generation WLAN

The next generation Wireless Local Area Network (WLAN) IEEE 802.11be regards Extremely High Throughput (EHT) as its core technology goal, among which multi-band capability and AP cooperation technology are regarded as its key technologies. However, the existing research on Orthogonal Frequency Division Multiple Access (OFDMA) protocol does not consider the multi-band capability and AP collaboration technology of IEEE 802.11be, so the improvement of system performance is limited and does not meet the EHT requirement. Especially when the nodes in overlapping coverage area have a large number of traffic, it is more important to improve the throughput of nodes in overlapping coverage area. In order to improve the throughput of nodes in overlapping coverage area, this paper proposes a spatial clustering group OFDMA protocol associated with multiple Basic Service Sets (BSSs). The protocol allows nodes in overlapping coverage area to be associated with multiple BSSs at the same time by using multi-band capability, that is, multi-association; Using AP collaboration technology allows nodes to perform parallel backoff with channels on multiple BSSs to improve access efficiency. Nodes in the overlapping coverage area are associated with the channels of multiple BSSs for parallel backoff. Node completed backoff and successfully accessed triggers a spatial clustering group (SCG) with close to its spatial location. OFDMA mode is used by SCG to access and transmit, thus increasing the access opportunities of nodes within overlapping coverage, thereby improving the throughput. The simulation results show that using the SCG-OFDMA protocol proposed in this paper associated with two BSSs, its throughput of nodes within overlapping coverage can achieve 353.41% higher than the IEEE 802.11ax protocol and 558.33% higher than the OMAX protocol respectively.

Contingency constrained phasor measurement units placement with n − k redundancy criterion: a robust optimisation approach

This study presents a novel approach for the contingency constrained phasor measurement units (PMUs) placement. The proposed approach is based on n − k redundancy criterion using robust optimisation. This security criterion ensures observability of the network under any contingency state, containing the loss of up to k PMUs. In the proposed method, the effects of zero injection and power flow measurements as well as possible contingency states (such as branch outage and single or multiple PMU loss) are considered. The non-linear modelling of observability function for measurements is reformulated by linearisation process. The resulting bi-level programming model is solved by its evolution to an equivalent single-level mixed-integer programming problem. The objective function of the optimal PMU placement is aimed at minimising the number of PMUs in a way that guarantees economic goals and the observability of all network buses. The advantage of this model is to significantly reduce the computational burden compared with other methods. The proposed method is tested on modified 7-bus test network, 118- and 2383-bus IEEE test networks. The results of the case studies clearly demonstrate the simplicity and efficiency of the proposed robust optimisation method in different cases.

An Experimental Connectivity Performance of Simple Wireless Mesh Implementation Using Wireless Distribution System (WDS)

Today wireless technology grows rapidly, especially in the field of telecommunications and communications. Computer networks now widely utilizes wireless. Wireless Mesh Network is one of the method which is use to communicate computer wirelessly. One important factor in application of wireless network is how to extend wireless signal coverage. Wireless Distribution System is one way to expand the wireless network by mean of wireless interconnection of access point on the network IEEE 8022.11. This study suggests how to build a simple wireless computer network using WDS technology and describes connectivity performance and its signal coverage. The test result of connectivity performance shows that the connectivity between two computers work properly for reliability and multi SSID testing. However, the connectivity was not success in multichannel testing. Furthermore the test result of coverage shows that the range of wireless signal coverage reaches 39 meters with different circumstance room.

Fault-Tolerance Evaluation of VANET Under Different Data Dissemination Models

Mobile Ad hoc Networks (MANETs) is a collection of wireless mobile nodes, which form temporary networks over infrastructure-less environments. Over the last few years, Vehicular Ad hoc Network (VANET) technology has been considered as an active research area. VANET is a sub class of MANET with some unique characteristics such as fast vehicle speed, frequent topology changes and restricted mobility on roads. The communication between vehicles provides a new avenue for different types of applications such as safety, traffic management, entertainment, etc. These applications are categorized based on how data is transmitted from source to destination. The performance of such applications does not only depend on routing protocols, but also on the data dissemination mechanism. Data dissemination in VANETs is a significant factor, which can be accomplished using four different models: Dynamic Source Dynamic Destination (DSDD), Dynamic Source Static Destination (DSSD), Static Source Dynamic Destination (SSDD), and Static Source Static Destination (SSSD). Each one of these models is suitable for specific types of applications. In this paper, the authors study and evaluate the fault-tolerance of VANET under different data dissemination techniques in terms of throughput, average End-to-End delay, and percentage of packet loss. the authors used NCTUns 6.0 network simulator and IEEE 802.11p wireless communication standard. Their findings show that DSDV is more fault-tolerant than both DSR and AODV in terms of packet loss percentage for all dissemination techniques. However, AODV shows better performance in average End-to-End delay and throughput under DSDD and SSDD techniques.

Cooperation of wireless networks IEEE 802.15.4 and IEEE 802.11b/g - introduction and measurements

Cooperation of wireless networks IEEE 802.15.4 and IEEE 802.11b/g - introduction and measurements