Delay In Wireless Networks Research Articles

Resource Allocation for Deterministic Delay in Wireless Control Networks

Meeting the high requirements of deterministic transmission in wireless control systems is very challenging, but also very important. In order to improve the determinacy of wireless short packet transmission, we optimize the communication resource required for multi-sensors in the wireless control system in this letter. In particular, we derive the probability of the transmission delay falling within a specified time window to characterize the deterministic transmission and then investigate the relationship between the delay determinacy and the wireless resources by taking the system control performance into account. We then optimize the transmission power spectral density of sensors and the transmission bandwidth allocation to maximize the delay determinacy, and obtain its suboptimal solution by numerical derivation. Finally, numerical results show that the proposed allocation achieves significantly greater the delay determinacy than that of other allocation schemes.

Node Selection Algorithm for Network Coding in the Mobile Wireless Network

In the multicast network, network coding has proven to be an effective technique to approach maximum flow capacity. Although network coding has the advantage of improving performance, encoding nodes increases the cost and delay in wireless networks. Therefore, minimizing encoding nodes is of great significance to improve the actual network’s performance under a maximum multicast flow. This paper seeks to achieve partial improvements in the existing selection algorithm of encoding nodes in wireless networks. Firstly, the article gives the condition for an intermediate node to be an encoding node. Secondly, a maximum flow algorithm, which depends on the depth-first search method, is proposed to optimize the search time by selecting the larger augmentation flow in each step. Finally, we construct a random graph model to simulate the wireless network and the maximum multicast flow algorithm to analyze the statistical characteristics of encoding nodes. This paper aims at the optimization to find the minimal number of required coding nodes which means the minimum energy consumption. Meanwhile, the simulations indicate that the curve of coding nodes tends to be a geometric distribution, and that the curve of the maximum flow tends to be symmetric as the network scale and the node covering radius increase.

Proactive fault-tolerant wireless mesh networks for mission-critical control systems

Although wireless networks are becoming a fundamental infrastructure for various control applications, they are inherently exposed to network faults such as lossy links and node failures in environments such as mining, outdoor monitoring, and chemical process control. In this paper, we propose a proactive fault-tolerant mechanism to protect the wireless network against temporal faults without any explicit network state information for mission-critical control systems. Specifically, the proposed mechanism optimizes the multiple routing paths, link scheduling, and traffic generation rate such that it meets the control stability demands even if it experiences multiple link faults and node faults. The proactive network relies on a constrained optimization problem, where the objective function is the network robustness, and the main constraints are the set of the traffic demand, link, and routing layer requirements. To analyze the robustness, we propose a novel performance metric called stability margin ratio, based on the network performance and the stability boundary. Our numerical and experimental performance evaluation shows that the traffic generation rate and the delay of wireless networks are found as critical as the network reliability to guarantee the stability of control systems. Furthermore, the proposed proactive network provides more robust performance than practical state-of-the-art solutions while maintaining high energy efficiency.

Real-time optimizations in energy profiles and end-to-end delay in WSN using two-hop information

This paper proposes a routing protocol established upon the IEEE 802.15.4a that enhances the delay and energy efficiency in Wireless sensor networks (WSN) using two-hop information. Owing to the miniaturized form and non-rechargeable nature, nodes deployed in WSN suffer from resource constraints which affects its performance in terms of delay and energy consumption. Motivated by this, the proposed scheme exploits two-hop information to improve the performance of WSNs. First, a robust metric function known as the potential relay information (PRI) is formulated. Unlike other metric functions, the PRI leverages the residual energy, distance and delay and assesses the link quality of neighbor nodes to ascertain that the selected next-hop forwarder delivers data packets to the destination with the highest possible quality of service (QoS). Second, a preemptive neighborhood state index (NSI) algorithm which enable nodes view two-hops down its routing path to make good forwarding decisions that minimizes delay and balances load traffic across the system is devised. Last, a proactive feedback technique is integrated to simplify the update of two-hop information in order to address the excessive pursuing of energy consumption resulting from overhead packets. Simulation results validate the efficiency of the proposed scheme and demonstrates improvements in network lifetime, packet delivery ratio (PDR), end-to-end delay and energy consumption over the compared algorithms. Moreover, the results reflect QoS which supports real timeliness.

Analysis of backlog and delay in downlink power-domain non-orthogonal multiple access wireless networks

As important quality-of-service (QoS) performance indicators, backlog and delay in wireless networks must be in compliance with the requirement of low-latency and high-reliability scenarios. Non-orthogonal multiple access (NOMA) is a novel and key wireless technology for the next generation of mobile communications. Its potential impacts on backlog and delay deserve to be specially studied. Meanwhile, the stochastic network calculus is an effective tool for analyzing network performances such as backlog and delay. In this paper, for both orthogonal multiple access (OMA) scheme and NOMA scheme, we utilize the stochastic network calculus to characterize respectively cumulative service processes of channels in a downlink network. Based on moment generating functions, the closed-form expressions of the upper bounds on backlog and delay are derived through the definite integral and special function. Simulation results validate reasonableness and effectiveness of the proposed approach. We show that in terms of backlog and delay, performances cannot be always improved by substituting NOMA scheme for OMA scheme, except when the channel gain gap between users is significantly big. Moreover, the sensitivity to the same factor such as arrival rate, transmission power and power allocation, differs from user to user in NOMA. By simulations, it is further demonstrated that the performance loss due to a finite buffer in practical scenarios is acceptable and sometimes negligible, as long as the buffer size is set to be just moderate.

Bi-adjusting duty cycle for green communications in wireless sensor networks

Green communications is a challenging issue for communications and networking. In order to save energy, nodes of the wireless sensor networks (WSNs) usually adopt the low duty cycle mode which brings a large delay to the event detection and data transmission to the sink and deteriorates the network’s timely processing of the event. In this paper, bi-adjusting duty cycle schedule (BADCS) scheme is proposed to reduce event detection latency as well as data routing delay for low duty cycle wireless sensor networks. BADCS scheme consists mainly of two duty cycle adjustment algorithms: (a) active slot asynchronous adjustment algorithm for nodes in the same sensing area; (b) the continuous adjustment algorithm for two adjacent nodes on the routing path with one active slot interval. Specifically, the operations are 2-fold. First, perform asynchronous operations on the active slots of the nodes in the same sensing area, so that the active slots of the nodes in the same sensing area are distributed as evenly as possible without overlapping. In this way, it is possible to reduce the latency by the time the event is perceived after its occurrence. Secondly, active slots of the nodes on the routing path are adjusted to be with pipeline style, so that when the nodes receive the data packet, they can route through the continuous active slots, thus greatly reducing the delay of data routing. Two adjustment algorithms of active slot are given in detail in this paper. The performance of BADCS mode is discussed in detail, and its performance is better than the previous strategy. Comprehensive experiments are conducted, and the results demonstrate that the proposed BADCS scheme significantly improves event detection performance in terms of detection latency, detection probability, and routing delay. Detection delay and routing delay are reduced as high as 3.91% and 56.22% respectively.

Analysis of energy efficient and network traffic delay in wireless networks using channel aware routing

AbstractThis article studies different analysis metrics of wireless networks using channel aware routing protocol. During communication the following characteristics are important performance metrics like network traffic delays and energy efficient. Energy Efficient is an important solution with limited buffer capacity and life time of battery in wireless environment. The status of each node can be identified by using co‐channel forwarding mechanism. The traffic delays can be measured by using Q‐Learning random early method and routing can be optimized by channel aware routing. The transmission changes in one node to another can be monitored by router database and energy level can be verified by additional changes in wireless network nodes. The network reliability is improved by reducing the communication delay, which uses various traditional routing protocols. Based on the demand of communication protocols, the router is designed to optimize the best network model. Based on the problem formation of open vehicle routing technique, it proves inherently NP‐hard. If it has reduced computation overhead, it will not perform well with the large scale framework. Therefore, the channel aware routing technique improves the performance by increasing the reliability of the network. The previous results are shown that efficient energy utilization and network traffic delays encountered the major and accuracy results are in below 60% In this article, we formulate to achieve analysis the energy performance and reduced traffic delay using co‐channels stochastic optimization procedure. The co‐channel method used to check various analytical bounds and check all the nodes are uniformly shares the energy level. The mathematical analysis report provides uniform distribution energy values and traffic delays. The simulation results are shows that efficient energy utilization and network traffic delays in wireless networks 75% achieved.

A Dynamic Channel Selection Algorithm of Data Forwarding in Wireless Mesh Networks

Wireless Mesh Networks (WMNs) is an emerging technology in networking, in which the devices (nodes) are configured with multi-radios, making the overall capacity improved significantly. Nodes avoid interference with each other by tuning to different channels of the spectrum space. When a node intends to communicate to other nodes, especially a node far away from it with multiple hops, it is critical to find the channel with largest bandwidth to forward the packet. A dynamic channel selection algorithm is presented in this article, by which each node is able to find its next hop based on the criteria of possible largest channel bandwidth to carry out the forwarding. The novel idea of our approach is that only three past numerical data are kept by each node, and then it is able to calculate the potential bandwidth capacity and continue the most efficient forwarding. Simulations experiments were conducted and the results demonstrated that our mechanism outperforms peer approaches in terms of bandwidth capabilities and delay in Wireless Mesh Networks.

WDAT‐OMS: A two‐level scheme for efficient data gathering in mobile‐sink wireless sensor networks using compressive sensing theory

This study addresses the problems of energy and delay in wireless sensor networks equipped with mobile sinks. The authors jointly consider the compressive sensing (CS) theory, cluster-based routing, and sink mobility to propose a data collection method named ‘weighted data aggregation trees with optimal mobile sink(s) (WDAT-OMS)’. The proposed scheme relies on a two-level architecture in which sensors are clustered at the first level. WDAT-OMS uses the CS theory along with load-balanced data aggregation trees to route packets from sensors to the corresponding cluster heads (CHs). In this regard, they present an efficient metric named ‘energy-and distance-aware CH selection’ to fairly distribute the energy consumption among different sensors. At the second level, one or more sinks traverse the network to collect the aggregated data of CHs. As an advantage, WDAT-OMS not only balances the energy consumption among different sensors but also increases the network scalability. Numerical results demonstrate that the proposed algorithm reduces energy consumption in comparison with ‘centralised clustering algorithm’, ‘energy-aware CS-based data aggregation’, and ‘energy-balanced high-level data aggregation tree ‘by 66%, 62%, and 63% for an average number of clusters, respectively. It also decreases the sink delay in comparison with the ‘single-hop data-gathering problem’ by 10%.

Hybrid Scheduling in Heterogeneous Half- and Full-Duplex Wireless Networks

Full-duplex (FD) wireless is an attractive communication paradigm with high potential for improving network capacity and reducing delay in wireless networks. Despite significant progress on the physical layer development, the challenges associated with developing medium access control (MAC) protocols for heterogeneous networks composed of both legacy half-duplex (HD) and emerging FD devices have not been fully addressed. Therefore, we focus on the design and performance evaluation of scheduling algorithms for infrastructure-based heterogeneous HD-FD networks (composed of HD and FD users). We first show that centralized Greedy Maximal Scheduling (GMS) is throughput-optimal in heterogeneous HD-FD networks. We propose the Hybrid-GMS (H-GMS) algorithm, a distributed implementation of GMS that combines GMS and a queue-based random-access mechanism. We prove that H-GMS is throughput-optimal. Moreover, we analyze the delay performance of H-GMS by deriving lower bounds on the average queue length. We further demonstrate the benefits of upgrading HD nodes to FD nodes in terms of throughput gains for individual nodes and the whole network. Finally, we evaluate the performance of H-GMS and its variants in terms of throughput, delay, and fairness between FD and HD users via extensive simulations. We show that in heterogeneous HD-FD networks, H-GMS achieves 16-30x better delay performance and improves fairness between HD and FD users by up to 50% compared with the fully decentralized Q-CSMA algorithm.

Delay and energy efficient dynamic bandwidth allocation algorithm for hybrid optical and wireless sensor networks

Abstract Wireless sensor network (WSN) in the hybrid optical and WSN (HOWSN) utilizes full advantages of broadband access facility. Passive optical network (PON) as the backbone of HOWSN ensures energy efficiency and meets the higher bandwidth demands. However, in the conventional HOWSNs, the sensor nodes of WSN stay in active state for 100% time, i.e., 100% duty cycle, with the optical access networks cause huge amount of energy wastage. This paper presents a new delay and energy efficient (DEE) dynamic bandwidth allocation (DBA) algorithm with multi-threaded polling approach for the optical network units of the HOWSNs. In the proposed scheme, to conserve the energy consumption of HOWSNs, the optical network units (ONUs) connected to the gateway nodes of WSN use 10% duty cycle, whereas the ONUs connected to the data network use 100% duty cycle. The performance of the proposed DEE scheme is evaluated by numerical simulations and compared those to the existing adaptive limited DBA (ALDBA) schemes, i.e., ALDBA1, ALDBA2 and ALDBAM, of HOWSNs. The simulation results prove that the proposed DEE scheme provides up to 32% and 38% more energy savings with lower end-to-end packet delay compared to the existing ALDBA1, ALDBA2 and ALDBAM schemes of HOWSNs, respectively.

RETRACTED ARTICLE: Dynamic scheduling and congestion control for minimizing delay in multihop wireless networks

RETRACTED ARTICLE: Dynamic scheduling and congestion control for minimizing delay in multihop wireless networks

A Multi-Objective Target-Oriented Cooperative MAC Protocol for Wireless Ad-hoc Networks With Energy Harvesting

In this paper, we present a cross layer cooperative medium access control (CMAC) protocol with energy harvesting (EH) capability. The small energy capacity and size of wireless nodes pose a great challenge to the longevity of wireless networks due to the cost of ensuring a reliable communication link between transmitting nodes characterized by path-loss, shadowing and fading effects. Besides, the inability of existing CMAC protocols to exhibit multi-objective target orientation limits their adaptation to the dynamic network requirements. To address this problem, we propose a protocol that harnesses the radio frequency (RF) EH in the physical layer to enhance the throughput, end to end delay, energy efficiency and network lifetime of energy constraint wireless networks. This ensures that beneficial cooperation is achieved in fairness and multi-objective target-oriented protocol. We then investigate the performance of deploying a selective time-switching relaying (TSR) and power-splitting relaying (PSR) schemes in the MAC layer stack for a decode-and-forward (DF) reactive relaying distributed network. In addition, the quality of service requirement, outage probability, and network lifetime optimization techniques, respectively were utilized for optimal power allocation. Also, we propose a distributed and adaptive relay selection algorithm to select the best helper node that improves the network performance and balance the network energy consumption. The results of simulation show that a multi-objective target orientation can be achieved by the proposed EH-CMAC protocol and outperforms EAP-CMAC protocol with respect to throughput, end to end delay, network lifetime and energy efficiency.

Wireless sensor network model with uncertain delay and packet loss based on intelligent fuzzy system

The utilization of fuzzy logic in WSNs is demonstrated to be a promising procedure since it permits joining and assessing various parameters in an effective way. Fuzzy logic is a decent methodology because of the execution prerequisites can be effectively supported by sensor hubs, while it can improve the general system execution. This paper studies the robust H∞ control considering time delay and packet loss related uncertainty in wireless sensor network system based on the basic theory of intelligent fuzzy systems. The model of a wireless sensor network with questionable time lag and packet loss is given first. The stability of the system is proved by the augmented Lyapunov functional and the linear matrix inequality (LMIs) method, with its demonstrated H∞ property. In order to solve the uncertain time delay and packet loss, the memory robust H∞ controller is proposed based on LMIs. Numerical examples and simulation results examines the potency of the presented method in solving the delay and packet loss of wireless sensor networks as well as the accuracy and precision of the system.

Short-Packet Physical-Layer Network Coding

This paper explores the application of physical-layer network coding (PNC) for short-packet transmissions. PNC can potentially reduce the communication delay in relay-assisted wireless networks and can thus be instrumental in realizing short-packet communication systems with stringent delay requirements. In this work, first, we first derive an achievability bound for channel-coded short-packet PNC systems. Based on the random-coding error-exponent, the bound serves as a benchmark for short-packet PNC operating with traditional preamble-aided channel estimation and XOR channel decoding. Second, we design a blind channel estimation algorithm and a code-aided channel estimation algorithm for short-packet PNC systems. Both outperform the traditional preamble-aided channel estimation for PNC systems operating with mismatched channel-state-information. As a case study, we compare the three algorithms for packets of 128 symbols over a two-way relay channel. The results show that the blind algorithm outperforms the code-aided algorithm and preamble-aided algorithm by almost 0.2 and 1.5 dB respectively. Furthermore, the blind algorithm achieves the target packet error rate of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> within 0.5 dB of the random coding bound of an imaginary system in which perfect channel-state-information is available at the relay at no cost (i.e., channel estimation is not required in the imaginary system). The bound and the algorithms give us a fundamental framework for applying PNC to short-packet transmissions.

ENHANCED WOA FOR MOBILE ENERGY EFFICIENT AND DELAY AWARE CLUSTERING IN WSN

The mobility, energy efficiency and reduction of delay in wireless sensor network (WSN) is most challenges that researchers working on it for more optimizations. The wale optimization algorithm is used in this paper after some modification in some steps to balance between the exploitation and exploration, we enhanced WOA for energy efficient and delay aware with respect to mobility of nodes out of clusters. The performance is evaluated by packet delivery ratio, delay, energy consumption, and throughput with considering the mobility of each node to be selected as cluster head. The proposed mechanism is compared with Hybrid FOA-WOA algorithm, we got good results in term of energy consumption, delay and throughput.

Delay and Lifetime Issues for Wireless Sensor Networks

The network delay and power consumptions are the two main factors governing the efficiency of wireless sensor networks. In this paper, our goal is to minimize the delay and maximize the lifespan of event-based wireless sensor networks in which activities occur infrequently.In such architectures, most of the power is fed on when the radios are on, ready for a packet to arrive.Sleep–wake scheduling is a highly efficient mechanism to prolong the lifetime of these power-constrained wireless sensor networks. However, sleep–wake scheduling could provide result with considerable delays. This research attempts to limit these delays by developing “anycast” based packet forwarding schemes that places each node opportunistically forwards a packet to the first neighboring node which wakes up amongst more than one candidate nodes.In this paper, we propose to optimize the anycast forwarding schemes by minimizing the anticipated packetdelivery delays from the sensor nodes to the sink node. Based on this analysis, we then provide a solution to the joint control problem of how to optimally manage the architecture parameters of the sleep–wake scheduling protocol and the any-cast packetforwarding protocol to maximize the network lifetime, with reference to a constraint on the expected end-to-end packetarriving delay.

A Distance-Based Data-Mule Scheduling Technique for Lesser Nodal Delay in Wireless Sensor Network

Nodal delay in wireless sensor network is an indisputable factor in the medium of communication. Factor such as changeability of communication devices, network topologies, packet-sizes, and transmission rate demands to develop data-mule queue scheduling technique. Our proposed data-mule scheduling technique accomplish this through simulations using standard software written in C# by controlling data-mule schedules that collects data from all the nodes connected to the hop. The scheme identifies the hierarchical positions of static source nodes and the distance of mobile source nodes from the hop with rescheduling based on the newly acquired distances. Source nodes applied with data-mule scheduling technique resulted to lower nodal delay. Transmission of packet-data is efficiently and effectively improved.

Analysis of incremental LMS adaptive algorithm over wireless sensor networks with delayed-links

Wireless sensor networks (WSN) are used for many delay-sensitive applications, e.g. military surveillance, emergency response, city management, etc. Therefore, modeling of delay is very important. This paper presents a study of the impact of sensors' sensing delay, process delay and transmission delay in the estimation of the desired unknown parameter in the WSN. Recently proposed wireless sensor networks, in the literature, assume perfect nodes and links, in view of delay. It means that no consideration has been made about the delay in the sensing, processing and, transmission procedures. The proposed method in this paper analyzes the behavior of the distributed incremental estimation algorithm in the presence of delay in wireless sensor networks. Weighted spatio-temporal energy conservation method is used to evaluate the transient and steady state behavior of the wireless sensor networks with delay without putting any restriction on regressor's distribution. The equations that illustrate mean square deviation (MSD), excess mean square error (EMSE) and mean square error (MSE) behavior of individual nodes, are driven. Also, simulations show that overall delay could be calculated to turn off nodes in some iterations without affecting the performance of the distributed estimation algorithm or adding extra latency to the network, which can improve power management strategies by modifying sleep-wake scheduling protocols. Eventually, it is shown that simulation results have a good match with derived theoretical expressions.

Minimizing end-to-end delay in multi-hop wireless networks with optimized transmission scheduling

The problem of transmission scheduling in single hop and multi-hop wireless networks has been extensively studied. The focus has been on optimizing the efficiency of transmission parallelization, through a minimum-length schedule that meets a given set of traffic demands using the smallest possible number of time slots. Each time slot is associated with a set of transmissions that are compatible with each other according to the considered interference model. The minimum-length approach maximizes the resource reuse, but it does not ensure minimum end-to-end packet delay for multiple source-destination pairs, due to its inherent assumption of frame periodicity. In the paper we study the problem of transmission scheduling and routing aiming at minimizing the end-to-end delay under the signal-to-interference-and-noise-ratio (SINR) model for multi-hop networks. Two schemes are investigated. The first scheme departs from the conventional scheduling approach, by addressing explicitly end-to-end delay and removing the restriction of frame periodicity. The second scheme extends the first one by featuring cooperative forwarding and forward interference cancellation. We study the properties of the two schemes, and propose novel mixed-integer programming models and solution algorithms. Extensive results are provided to gain insights on how the schemes perform in end-to-end delay.