Algorithm For IEEE Research Articles

Rate Adaptation Algorithms in IEEE 802.11 Wireless Networks: A Comparative Study

Rate Adaptation Algorithms in IEEE 802.11 Wireless Networks: A Comparative Study

Reconfiguration of harmonic polluted distribution network using modified discrete particle swarm optimization equipped with smart radial method

AbstractDistribution network reconfiguration (DNR) is capable to improve indices of power systems by changing the distribution network (DN) topology under normal conditions. Here, DNR is implemented to improve the power quality (PQ) and power losses of DN. Furthermore, to achieve better optimum in DNR, discrete particle swarm optimization (DPSO) algorithm is equipped with a smart radial method. The proposed algorithm is faster than other metaheuristic methods due to the prevention of regeneration non‐radial configurations. In addition, the algorithm increases the probability of finding the optimal configurations using the mutation function. The results clearly demonstrated the positive effect of DNR in improving harmonic losses, total harmonic distortion (THD), and power losses. Furthermore, the proposed method is compared with other metaheuristic algorithms in IEEE 33 bus DN, IEEE 69 bus DN, and real 95‐bus DN in presence of photovoltaic (PV). The results show that the developed algorithm leads to the better or same accuracy and speed in all comparisons. In addition, results indicated that considering the summation of fundamental and harmonic losses compared to only fundamental losses in DNR can lead to further energy saving in DNs.

An Adaptive Network Design for Advanced Metering Infrastructure in a Smart Grid.

A smart grid is a next-generation intelligent power grid that can maximize energy efficiency by monitoring power information in real time and by controlling the flow of power by introducing IT communication technology to the existing power grid. In order to apply a wireless communication network to a smart grid, it is necessary to be able to efficiently process large amounts of power-related data while enabling a high level of reliability and quality of service (QoS) support. In addition, international standards-based design is essential considering compatibility and scalability. The IEEE 802.15.4 standard is considered to be the most powerful communication method for processing data through the smart grid AMI. To reduce the energy consumption, as the duty cycle of the superframe increases, the probability of the congestion increases. However, this binary exponential algorithm in IEEE 802.15.4 standard does not account for the application of traffic characteristics that essentially negatively affect the smart grid network performances in terms of packet delivery ratio and time delay. Therefore, in this paper, we propose a new transmission scheme to reduce performance degradation by excessive collisions in the content access period (CAP), when data transmission is performed in IEEE 802.15.4 applied to smart grids. In addition, we investigated the main research topics required when applying wireless networking technology to smart grids and suggested improvement measures. Simulation results showed that the proposed scheme increased the data delivery rate and reduced the latency, and it was confirmed that reliability was improved.

Deep Learning-Based Nonstationary Channel Prediction in Tactical Vehicle-to-Vehicle Communication Environments

In this paper, we focus on the vehicle-to-vehicle dynamic channel in tactical communication environments, which shows time-varying and nonstationary characteristics due to the fast mobility, directional antennas, and harsh terrain. These situations present great challenges for the channel state information (CSI) acquisition. To obtain an accurate CSI and reduce pilot overhead, we propose a CSI predictor based on the long short-term memory (LSTM) network. As an improved recurrent neural network (RNN), LSTM units have an excellent learning result on both long- and short-term inputs by adding the gating mechanism. Using the outdated sampling CSI sequence as input data of LSTM units enables the predictor to extract complex data characteristics and capture the temporal law of the nonstationary channel. Simulation results are demonstrated to verify that the LSTM-based predictor has better performance than conventional algorithms in IEEE 802.11p standard. Additionally, the key factors that affect the performance of the proposed predictor are further analyzed.

The Possibilities to Reduce Arc Flash Exposure with Arc Fault Eliminators

This paper presents a method to limit the arc energy and hence the hazard risk category value according to IEEE 1584 by using a system of two oppositely connected multi-sectional thyristor branches. A test circuit for testing the effectiveness of a thyristor arc eliminator was designed and constructed. Arc ignition inside electrical switchgear can be a source of danger for technical personnel. The arc energy calculated according to the algorithms in IEEE 1584 can be significantly reduced by using multi-sectional arc eliminator MSAE. For the actual measuring object, the calculation of the hazardous arc flash zone and the hazard category was carried out for the system not equipped with an arc eliminator, and then the same was performed in a system with an arc eliminator. In parallel, the pressure inside the closed polyvinyl chloride (PVC) electrical box enclosure was measured and then compared with the calculated pressures that could occur during an arc fault. It was found that a Multi-Sectional Arc Eliminator (MSAE) effectively protects devices supplied from low voltage networks against the effects of short circuit or arc fault, such as the sudden increase of gas pressure inside the switchboard, which may cause it to break, significantly reduce the loss of electrode material, limit the spread of hot electrode material outside the switchgear, and also significantly reduces the energy of the electric arc.

Quick and efficient network access schemes for IoT devices

In an IoT (Internet of Things) network, nodes need first to access the network resources before they can transmit data. If the data to be transmitted require real-time guarantees, then the node should not be stuck in the process of accessing resources. Quick and efficient access to the network resources is desirable for timely data communication. To this end, we have studied the IEEE 802.15.4 and IEEE 802.15.4e-TSCH standards and have proposed energy-efficient algorithms to ensure that the nodes can access the resources at the earliest. We have proposed a “Device Registration” algorithm for IEEE 802.15.4 networks, which aims at increasing accessibility of the Guaranteed Time Slots (GTSs) available in the superframe. The algorithm can be implemented by making minor modifications to the parameters within the existing MAC framework. Similarly, we have proposed a “Sparse Beacon Advertisement”, a beacon scheduling algorithm, for IEEE 802.15.4e-TSCH networks that aims at reducing the wait time for a new node before it joins the network, even when there are few beacons being advertised. Both these algorithms have been evaluated extensively using simulations and experiments on a testbed. Our results show that in an IEEE 802.15.4 network, with the proposed algorithm, nodes are twice as successful in accessing the GTS resources as they were before. Similarly, Sparse Beacon Advertisement reduces the joining times by at least 60% in an IEEE 802.15.4e-TSCH network.

Dynamic Slot Allocation Using Non Overlapping Backoff Algorithm in IEEE 802.15.6 WBAN

A dynamic slot allocation scheme using non-overlapping contention windows is presented in this paper to improve the utilization of the IEEE 802.15.6 Wireless Body Area Network (WBAN) superframe. Firstly, a Non Overlapping Backoff Algorithm (NOBA) that avoids inter-priority collisions due to backoff is presented. The results of this scheme are compared with the standard Binary Exponential Backoff (BEB) and the Prioritized Fibonacci Backoff (PFB) schemes. The NOBA provides improvement in the sum throughput, individual throughputs and access delay. Secondly, to avoid the wastage due to fixed slot size, a Dynamic Slot Allocation (DSA) scheme is introduced. It assigns the dynamic slots and phases in a superframe depending on the traffic requirements. Thirdly, a DSA-NOBA scheme that combines both the DSA and the NOBA is presented. The performance of DSA-NOBA is compared against the standard IEEE 802.15.6 superframe (with BEB) and Dynamic Phase Allocation (DPA) schemes using the individual throughput, sum throughput, latency, energy, superframe time and superframe efficiency as performance metrics. Over a range of payload sizes, the DSA-NOBA makes the superframe 50% more efficient than the standard IEEE 802.15.6 superframe with BEB, consequently also providing improvement in all the performance metrics. The most notable among them is energy, whose consumption is reduced by half when compared with the standard.

Evaluation of Rate Adaptation Algorithms in IEEE 802.11 Networks

Wireless technologies are being used in various applications for their ease of deployment and inherent capabilities to support mobility. Most wireless standards supports multiple data rates that may vary between few Mbps to few Gbps. Reaching the maximum supported data rate is what most application seek for. Nevertheless, the choice of data rates is very closely related to the quality of communication links and their stability. IEEE 802.11 standard introduced multi-rate support, since then, a lot of research has been done on rate adaptation, dealing with the different parameters that lead to an estimation of the channel conditions and the metrics that affect the network performance. In this paper, we present some of the popular rate adaptation schemes and summarize their characteristics. We categorize them as well into different categories according to their design and functionalities in terms of the strategies that are used to estimate channel conditions and decision making. We implemented some algorithms from the different categories in the network simulator NS-3 in order to evaluate their performance under different scenarios in Ad hoc and infrastructure modes. We present the lessons learned as well as our insights for future research work that can enhance the current approaches in the literature.

CARA-OHT: Collision-Aware Rate Adaptation for Optimal High-Throughput in IEEE 802.11s Wireless Mesh Networks

The wireless mesh network (WMN) is a future network technology that develops single-hop wireless local area networks (WLANs) into multi-hop wireless mesh networks, based on the IEEE 802.11s standard. However, this development still presents many challenges, such as determining the best route between sources and destinations, especially taking into account the use of the medium access control (MAC) and physical (PHY) layers of IEEE 802.11n/ac. Some papers have proposed rate adaptation algorithms particularly for single-hop networks; however, these only focused on mechanisms to find data rates suitable for channel conditions. In IEEE 802.11s WMNs, the design of the rate adaptation algorithm is more challenging. Besides considering the problem of channel quality and optimal throughput, it is necessary to also consider the problem of collision and the best route. It is important to take collision into account because the collision probability in multi-hop mesh networks is higher than that in single-hop networks and can lead to a lower throughput. Rate adaptation algorithms for IEEE 802.11s WMNs have been proposed in other papers, but they also do not consider the use of the MAC and PHY layers of IEEE 802.11n/ac. In this paper, we propose the collision-aware rate adaptation for optimal high-throughput (CARA-OHT) algorithm for WMN IEEE 802.11s. An evaluation through the extensive use of a network NS-3 simulator shows that the proposed algorithm exhibits a higher throughput than previously developed algorithms.

Multi-Dimensional Busy-Tone Arbitration for OFDMA Random Access in IEEE 802.11ax

IEEE 802.11ax has adopted orthogonal frequency division multiple access (OFDMA) to support multi-user (MU) transmissions. There exist two uplink MU OFDMA access methods in IEEE 802.11ax. The first one is uplink OFDMA random access (UORA) in which stations randomly select resource units (RUs) to send physical protocol data units (PPDUs), so its access efficiency is low. The second one is uplink OFDMA nonrandom access (UONRA) in which the access point (AP) schedules MU transmissions based on buffer status reports (BSR) from stations. However, stations usually rely on UORA to send BSRs, so the low efficiency of UORA can be a bottleneck of UONRA. Thus, UORA needs to be renovated to improve the performance of itself and UONRA. To this end, a multi-dimensional busy-tone arbitration (MBTA) mechanism is developed in this paper to reduce collisions among stations contending the same RU. Since there lacks an algorithm in IEEE 802.11ax to support coexistence of UORA and UONRA, a dynamic access-method selection (DAMS) algorithm is designed for the AP and stations to choose an optimal access method. Both MBTA and DAMS are analyzed rigorously and are further validated via simulations. The analytical and simulation results show that: 1) The MBTA dramatically improves the access efficiency of UORA; 2) DAMS always achieves a higher throughput than both UORA and UONRA.

An Interference-Aware Rate and Channel Adaptation Scheme for Dense IEEE 802.11n Networks

Rate adaptation, which dynamically chooses transmission rate provided at the physical layer according to the current channel conditions, is a fundamental resource management issue in IEEE 802.11 networks with the goal of maximizing the network throughput. Traditional rate adaptation algorithms for IEEE 802.11n networks do not consider the interference problem, which becomes much more serious due to the rapid deployment of IEEE 802.11n devices and large number of mobile terminals. In this paper, an interference-aware rate and channel adaptation scheme RaCA for intensive IEEE 802.11n networks was proposed. Firstly, RaCA leverages RSSI and CSI information together to measure the current channel conditions at the receiver side. RSSI is a coarse-grained indicator and CSI is a fine-grained indicator. Secondly, a two-stage rate adaptation scheme TSRA was designed, which can quickly adapt to optimal bit rate based on RSSI and CSI information. Finally, a quorum-based channel adaptation algorithm QCA was proposed, which does not need control channel. If channel suffers severe interferences, RaCA calls QCA to choose another channel to work on. Simulation and testbed implementation results demonstrate that RaCA achieves significant throughput gain over SampleLite and Minstrel-HT.

A Cross-layer Neighbour Discovery Algorithm in Ad hoc Networks based on Hexagonal Clustering and GPS

Neighbour discovery is an important part of ad hoc networks. In a typical ad hoc routing protocol, each node broadcasts hello messages at a fix time interval to update the latest information of neighbour nodes and tracks neighbour relationship between the nodes. However, the higher density of network nodes, the more collisions happen between the hello messages, the more bandwidths are wasted and the worse network congestion produces. So we design a cross-layer neighbour discovery algorithm, ND_HC, to actualize the neighbour discovery in MAC layer. In this algorithm, the hello messages are produced in MAC layer, and are sent in TDMA method with the help of hexagonal clustering and GPS, which reduce packets collision probability and improve throughput in the network. The NS-2’s simulation results show that compared to the traditional neighbour discovery algorithm in IEEE 802.11, the proposed algorithm improves the efficiency of neighbour discovery obviously.

A goodput distribution model for planning IEEE 802.11 WBNs in built environments

IEEE 802.11 wireless backhaul networks (WBNs) have emerged as a practical solution for bridging access points and backbone networks with low cost and ease of installation. However, the IEEE 802.11 protocol operates in the unlicensed spectrum and experiences unregulated interference, making it difficult to guarantee quality of service (QoS). With newer and farther reaching applications being densely deployed in built environments, such as small cell cellular networks and smart grids, users are increasingly expecting high QoS and fair access. This increased expectation for high QoS motivates the study of goodput models for planning IEEE 802.11 WBNs in built environments. In this paper, we design a goodput distribution model with consideration of structured placement of WBN nodes in built environments and validate our goodput model through simulations. The results show that our model provides an accurate prediction of goodput distribution in IEEE 802.11 WBNs under different traffic demands and radio propagation conditions. Such a goodput model is useful for node placement and optimising routing and channel assignment algorithms in IEEE 802.11 WBNs.

DIVA: a distributed divergecast scheduling algorithm for IEEE 802.15.4e TSCH networks

IEEE standardized a highly efficient, low power, reliable, deterministic and time–frequency enabled medium access control protocol, IEEE 802.15.4e time slotted channel hopping (TSCH) as an amendment to the medium access control (MAC) protocol defined by the IEEE 802.15.4 standard. Once a communication schedule is built, the IEEE 802.15.4e TSCH is able to execute such a communication schedule. IEEE 802.15.4e TSCH standard lea ves out of scope defining how that communication schedule is built, updated and maintained. In order to fill this gap, we introduce such a scheduling algorithm, called as DIVA. DIVA is specifically designed for IEEE 8092.15.4e TSCH networks. It is a totally distributed scheduling algorithm for divergecast traffic where divergecast means that traffic flows in all directions in contrast to convergecast where traffic flows from leave nodes to root. In order to gain more comprehension about DIVA, we conducted extensive simulations. We also compared DIVA with Berkeley’s Aloha-based algorithm.

Evaluation of the Minstrel-HT Rate Adaptation Algorithm in IEEE 802.11n WLANs

Evaluation of the Minstrel-HT Rate Adaptation Algorithm in IEEE 802.11n WLANs

Fast convergence resource allocation in IEEE 802.16 OFDMA systems with minimum rate guarantee

Resource allocation in the context of OFDMA-based systems is challenging, given a combinatorial nature of the problem. In the context of IEEE 802.16 systems this problem is further exacerbated by additional constraints that are faced with its two dimensional frame nature. The main challenges associated with resource allocation in these systems are: mapping the allocated bandwidth resources to users in this two dimensional frame, power and frequency allocation, and QoS guarantee. This optimization problem can usually be solved by an iterative algorithm. The solutions proposed have a constant step size in iterations which causes a long convergence time. For this reason the solutions proposed are not applicable in IEEE 802.16 systems. In this paper we propose a novel resource allocation algorithm in IEEE 802.16 systems which has an adaptive step size in iterations while taking into account the minimum rate guarantee for users.

A High-Efficiency Multiplierless Symbol Synchronization Algorithm for IEEE802.11x WLANs

This work presents a novel high-efficiency multiplierless symbol synchronization algorithm for IEEE 802.11x wireless local area networks (WLANs). In our proposed scheme, according to IEEE 802.11x specifications, the element of the local known training sequence in the frame header is approximated and represented by its nearest value of integer power of 2. The multiplication in the cross-correlation for OFDM symbol synchronization can be directly reduced to a shift operation. Therefore, the correlator in the OFDM symbol synchronization for IEEE 802.11x WLANs can be economically implemented by merely utilizing the logic resources in hardware without notable performance loss. Since the multiplers and adders are replaced by the simple shifters, the implementation complexity of the correlator is significantly reduced. Experimental results demonstrate that our proposed method can achieve almost the same performance as the original correlation algorithms with multipliers, and has higher correct detection probability than the existing multiplierless technique at given low SNR.

An End-to-End Delay-based Scheduling Algorithm in IEEE 802.15.4e Networks

This paper proposes a novel scheduling algorithm using multi-channel and multitimeslot with the objective of reducing the end-to-end (e2e) delay in a tree-based wireless sensor network. The algorithm exploits a staggered timeslot allocation in terms of e2e paths, rather than the one with individual branches. It also increases simultaneous data transmissions. The proposed algorithm is shown to be superior to an existing algorithm with non-e2e delay based, in terms of e2e delay.

Evaluating the Performances of Double Precision Floating Point Matrix Multiplication

Most of the DSP applications make matrix multiplication as basic kernel. We proposed an algorithm for IEEE 754 Double Precision floating point matrix multiplication (Level-3 BLAS). The design is based on rank-2update scheme, which handles matrix of arbitrary sizes and is centred on pipelined multiplication the matrices are stored in dedicated on-chip BRAM; the aim of this investigation is to advance the performance in terms of delay and area. The hardware architectures are described in Verilog HDL synthesized for a family virtex5 and device SX240T FPGA, which scale more than 40 processing elements. Various parameters like LUTs, Slices, bonded IOBs, frequency, delay, Power, CPU Completion time and Memory usage are analysed. Rank-2 scheme consumes a power of 0.382 watt and has a delay of 7.582 ns. The proposed algorithms consume 10% less area and 8% less delay than the rank-1 update scheme.

APPLYING GAME THEORY IN 802.11 WIRELESS NETWORKS / ŽAIDIMŲ TEORIJOS TAIKYMAS IEEE 802.11 TINKLUOSE

IEEE 802.11 is one of the most popular wireless technologies in recent days. Due to easiness of adaption and relatively low cost the demand for IEEE 802.11 devices is increasing exponentially. IEEE works in two bands 2.4 GHz and 5 GHz, these bands are known as ISM band. The unlicensed bands are managed by authority which set simple rules to follow when using unlicensed bands, the rules includes requirements as maximum power, out-of-band emissions control as well as interference mitigation. However these rules became outdated as IEEE 802.11 technology is emerging and evolving in hours the rules aren’t well suited for current capabilities of IEEE 802.11 devices. In this article we present game theory based algorithm for IEEE 802.11 wireless devices, we will show that by using game theory it’s possible to achieve better usage of unlicensed spectrum as well as partially decline CSMA/CA. Finally by using this approach we might relax the currently applied maximum power rules for ISM bands, which enable IEEE 802.11 to work on longer distance and have better propagation characteristics. Lengvai pritaikoma ir panaudojama įvairiuose sprendimuose IEEE 802.11 technologija tapo viena populiariausių bevielių technologijų. IEEE 802.11 įrenginiai veikia nelicencijuotais 5 GHz ir 2,4 GHz dažniais – pramonės, mokslo ir medicinos dažnių ruože (angl. Industrial, scientific and medical (ISM) radio bands). Šiam dažnių ruožui taikomos supaprastintos taisyklės, nurodančios, kad įrenginiai, veikiantys ISM dažniais, turi atitikti tik maksimalią signalo perdavimo galią ir interferencijos triukšmus bei neviršyti triukšmo normos už dažnių ruožo ribų. Tobulėjant IEEE 802.11 protokolo įrangai, šios taisyklės tapo nelanksčios ir neatitinka dabartinių įrenginių galimybių. Straipsnyje pristatomas naujas IEEE 802.11 įrenginių kanalo prieigos metodas, pagrįstas žaidimų teorija. Parodoma, kad taikant šį metodą galima pagerinti spektro panaudojimo efektyvumą bei kartu iš dalies atsisakyti dabar egzistuojančio CSMA/CA mechanizmo IEEE 802.11 įrenginiuose. Taikant efektyvesnį kanalo prieigos metodą atsiranda galimybė laikytis lankstesnių siųstuvo galių taisyklių ir taip padidinti skvarbą uždarose patalpose bei įrangos veikimo nuotolį.