Adaptive Backoff Research Articles

Improved Adaptive Backoff Algorithm for Optimal Channel Utilization in Large-Scale IEEE 802.15.4-Based Wireless Body Area Networks

Improved Adaptive Backoff Algorithm for Optimal Channel Utilization in Large-Scale IEEE 802.15.4-Based Wireless Body Area Networks

A receiver-driven transport protocol using differentiated algorithms for differential congestion in datacenters

With the continuous development of applications, data centers run application traffic from various service providers, and the requirements for data center networks are also increasing. Congestion control has always been a hot topic of discussion. Prevalent sender-driven transport protocols require adjusting their sending rate after network congestion occurs, and the long feedback delay makes them susceptible to a buffer overflow. Therefore, receiver-driven transport protocols are proposed, and the receiver adopts credits to allocate downlink bandwidth to overcome network congestion. This type of scheme solves last-hop congestion and reduces congestion feedback latency. However, the existing receiver-driven transport protocol is insensitive to congestion location and thus reacts inaccurately to congestion. To address this problem, this paper proposes a congestion control algorithm with congestion location awareness. In this scheme, 1) we first design an ECN-based congestion detection method to achieve lightweight congestion types awareness, i.e., instantaneous congestion and continuous congestion. 2) Based on this, we further design a differentiated transmission control strategy. For instantaneous congestion, we adopt adaptive backoff and delay control algorithms. For continuous congestion, we employ a rate control algorithm to reduce in-network congestion. This does not require complex modifications to the switch. In our evaluation, the overall average flow completion time (FCT) of DCC is up to 21%, 89%, 1.5×, and 3.4× better than Homa, ExpressPass, Timely, and pHost, respectively.

Novel Listen-Before-Talk Access Scheme With Adaptive Backoff Procedure for Uplink Centric Broadband Communication

To cater for the data-hungry Internet of Things (IoT) applications, Uplink Centric Broadband Communication (UCBC) has been identified as a new service class in the vision of 5.5G, where the unlicensed spectrum has been regarded as a promising solution to boost the uplink capacity. The New Radio Unlicensed (NR-U) network adopts Category-4 (Cat4) Listen Before Talk (LBT) access scheme to exploit the unlicensed spectrum and fairly coexist with the incumbent Wireless Fidelity (WiFi) network. However, the existing Cat4 LBT access scheme adopts single fixed energy detection (ED) threshold and Backoff speed, which cannot adapt to the sophisticated interference and achieve the expected uplink system throughput. To tackle this issue, in this paper, we develop a novel Cat4 LBT access scheme with adaptive Backoff procedure for UCBC, which includes instantaneous interference level quantification, instantaneous interference level sharing, and Backoff speed determination. The results have shown that our proposed adaptive Cat4 LBT scheme achieves over 70% uplink system throughput performance gain where cell throughput of NR-U network rises by over 100%, and cell throughput of WiFi network increases by 25%.

ABM-V: An Adaptive Backoff Mechanism for Mitigating Broadcast Storm in VANETs

In vehicular ad hoc networks (VANETs), the broadcast storm problem may disable road safety applications and cause congestion or traffic accidents. Existing schemes propose broadcast storm mitigation by reducing the number of relay vehicles. Concurrently, in improving reachability, these schemes stipulate that vehicles expected to transmit packets to more next-hop neighbors have higher relay priority. However, the potential redundancy caused by duplicate reception by neighbors is ignored, which exacerbates the contention and collisions in transmission. This paper proposes an adaptive backoff mechanism for mitigating broadcast storm in VANETs (ABM-V). Specifically, the receiver estimates the expected benefit and redundancy by combining the distribution of neighbors. Then, the receiver adaptively adjusts the backoff time by utilizing Dempster-Shafer evidence theory. Finally, the receiver with the shortest backoff time becomes the relay and rebroadcasts the packet to its neighbors. Simulation results illustrate that ABM-V significantly reduces the rebroadcast ratio and redundancy ratio compared with the existing typical schemes while maintaining stable reachability.

An adaptive backoff selection scheme based on Q-learning for CSMA/CA

An adaptive backoff selection scheme based on Q-learning for CSMA/CA

A Handshake-Based Low Delay MAC Protocol in Hybrid Topology for Urban Lake Monitoring

Underwater acoustic sensor networks (UASNs), which adopt acoustic communication, have been widely used underwater, such as in oceans and rivers, for monitoring applications. However, the UASNs designed for urban lake monitoring are facing challenges and are seldom regarded. Based on the analysis of the features of the urban lakes and the monitoring requirements, a UASN system is designed in this article. The node deployment strategy is discussed to balance the node density and transmission bandwidth. Then a hybrid topology is proposed to meet the monitoring requirements, in which the nodes on the water surface construct a 2-D ring topology, and the nodes underwater construct a 3-D grid structure. Based on this topology, a media access control (MAC) protocol-improved handshake-based low delay (i-HALO) is designed which improves the existing handshaking mechanism with a dynamic adaptive backoff algorithm to avoid unnecessary back off. As the result, the high delay problem is addressed and the “one handshake, multiple transmission” is realized. The channel access delay is analyzed theoretically and the formula of waiting time for a frame before sending is given. The performance of throughput and transmission delay under different node densities and frame lengths are simulated. The results indicate that a node having about 13 neighbors will have the best performance on throughput, and when the frame length is longer than 100 bytes, the throughput and delay will have fluctuation. In comparison with existing protocols, i-HALO has a better performance on throughput, delay, frame reception rate (FRR), and fairness.

Utilization of a Wireless Network Performing CSMA/CA with Random Backoff Algorithm

Optimizing WLAN performance in IEEE 802.11 network with extremely different working environments is a difficult task. We must use a network that can provide the most benefits to its end-users to improve network strength and data transmission. To increase performance in this congested situation, we construct an adaptive backoff algorithm for the IEEE 802.11 DCF that enhances in congested network conditions, system throughput is improved, the collision probability is reduced, and good fairness is maintained. This paper deals with the utilization of networks for different backoff strategies for different network conditions. The results obtained were comparatively much better than the existing methods.

An energy‐efficient priority‐based packet scheduling mechanism for enhancing quality of service in mobile ad hoc network

AbstractIn today's world, a mobile ad hoc network plays a predominant role for numerous applications such as education, entertainment, emergency services, tactical services, and home applications. The performance of IEEE 802.11 based wireless ad hoc networks degrades due to high contention for the shared medium among multiple ad hoc nodes. However, the shared medium can be accessed by multiple nodes, which causes link collisions and packet drop at the link level. These kinds of packet drops have a direct impact on the overall performance of the transmission control protocol (TCP). In this article, a new robust prioritized packet scheduling with adaptive backoff window (PPSAB) mechanism has been proposed to enhance the quality of service of TCP in the wireless scenario. In order to determine the congestion in the network, the proposed PPSAB mechanism anticipates the cross‐layer parameters instead of transport layer parameters. The proposed access scheme assures minimized collisions and energy by setting the node level access to prevailing network parameters. The performance of the proposed PPSAB has been evaluated using an NS‐2 environment and the results manifest that the normalized overhead is reduced by 20% and network throughput is increased by 17% than the existing methods.

An energy‐efficient MAC protocol based on receiver initiation and multi‐priority backoff for wireless sensor networks

Wireless Sensor Network (WSN) has been widely used with its main characteristics of resilience, scalability, and mobility. However, the node battery capacity in WSN is limited. In addition, in scenes with emergencies such as forest ecological monitoring, data packets of wildfire emergencies have higher real-time requirements than periodic normal data. Therefore, this paper proposes an energy-efficient MAC protocol based on Receiver initiation and Multi-Priority Backoff (RMP-MAC). RMP-MAC adopts the wake-up matching mechanism initiated by the receiver. The sender adjusts its schedule according to the wake-up information of the receiver to match the receiver, which reduces the energy consumption of idle listening. In addition, RMP-MAC proposes a multi-priority factor adaptive backoff mechanism based on event priority, node remaining energy level, and the number of data packets waiting in the transmission queue, ensuring the transmission of emergency data in the actual situation of forest ecological monitoring. Simulation experiments show that compared with PB-MAC, AP-MAC, and MPQ-MAC, RMP-MAC can reduce energy consumption by 20.22%, 12.47%, and 6.62% respectively. In addition, it has improved in the average collisions, network throughput, and average delay of packets.

An adaptive backoff and dynamic clear channel assessment mechanisms in IEEE 802.15.4 MAC for wireless body area networks

The low power connectivity and short distance communication qualities of the IEEE 802.15.4 standard suits its application in wireless body (personal) area networks (WBAN). IEEE 802.15.4 protocol use carrier sense multiple access and collision avoidance (CSMA-CA) medium access control (MAC) mechanism for aperiodic data communication; however, it faces performance degradation with a gradual increase in the number of network devices. Performance challenges arise due to; several heterogeneous and dynamic packet sources sharing limited resources during contention in a finite backoff period, association delay, and traffic channel access through clear channel assessment (CCA) algorithms. Due to such constraints, channel conditions increase packet collision and queuing delay, which raises power demand and impedes performance indicators, such as throughput, packet delivery ratio (PDR), and end to end (E2E) delay. This article proposes an alternative combination of the backoff and CCA adaptation mechanisms to improve WBAN performance characteristics in a highly dynamic environment considering network residue energy, PDR, throughput, and E2E delay. We use the Markov model to demonstrate a theoretical analysis of the proposed CSMA-CA MAC mechanism. A comparative study shows the proposed methods outperform conventional protocol in PDR, throughput, and reduced E2E delay by 13.1%, 21.44%, and 41.13%, respectively, where energy efficiency drops by 0.43%.

A Novel Collision Supervision and Avoidance Algorithm for Scalable MAC of Vehicular Networks

In order to meet low-latency and ultrareliable requirements on safety services in vehicular networks, this paper proposes a novel Collision supervision and avoidance (CSA) algorithm for the contention based scalable media access control protocol. The twodimensional Markov chain model of adaptive backoff state transition criterion in CSA has been built, which could efficiently match the backoff states of nodes to the dynamic changes of vehicular networks. The scalable transmissions can be achieved through supervised trend and matching backoff mechanisms with three adaptive backoff modes. The packet transmit probabilities for the backoff modes have been derived with the theoretical result of the enhanced throughput. The simulation results show the remarkable scalability performance such as normalized throughput > 0.92, PDR > 86% and delay < 6.5ms even in the high-density and high-mobility environment.

Optimization Method of Adaptive Backoff and Duty Cycle for S-MAC Protocol in Wireless Sensor Networks

As a matter of fact that the network traffic has a great influence on the binary exponential backoff mechanism, duty cycle mechanism, and fixed transmission power mechanism adopted by the Sensor Medium Access Control (S-MAC) protocol. The paper proposes an Adaptive Backoff and Duty Cycle for S-MAC protocol (ABDC-SMAC). In the backoff mechanism, considering the failure times of channel competitions, the length of buffer queue, and the node residual energy across the board, a cross-control backoff mechanism is proposed. In the duty cycle mechanism, the network traffic is judged by the average network flow factor. Based on the average network flow factor, the value of duty cycle can change around its initial value. In the power control mechanism, the minimum transmission power can be obtained by the Friis formula. At the same time, the exponential formula following the change of network traffic is selected and multiplied by the minimum transmission formula. The simulation results show that the performance of proposed ABDC-SMAC protocol is improved obviously on energy consumption and transmission delay.

A Collision-aware MAC Protocol for Efficient Performance in Wireless Sensor Networks

Both IEEE 802.11 and IEEE 802.15.4 standards adopt the CSMA-CA algorithm to manage contending nodes’ access to the wireless medium. CSMA-CA utilizes the Binary Exponential Backoff (BEB) scheme to reduce the probability of packet collisions over the communication channel. However, BEB suffers from unfairness and degraded channel utilization, as it usually favors the last node that succeeded in capturing the medium to send its packets. Also, BEB updates the size of the contention window in a deterministic fashion, without taking into consideration the level of collisions over the channel. The latter factor has a direct impact on the channel utilization and therefore incorporating it in the computation of the contention window’s size can have positive impacts on the overall performance of the backoff algorithm. In this paper, we propose a new adaptive backoff algorithm that overcomes the shortcomings of BEB and outperforms it in terms of channel utilization, power conservation, and reliability, while preserving the fairness among nodes. We model our algorithm using Markov chain and validate our system through extensive simulations. Our results show a promising performance for an efficient backoff algorithm.

Priority-Aware Fast MAC Protocol for UAV-Assisted Industrial IoT Systems

Many hazardous industrial incidents can occur due to the inadequate and inefficient monitoring of the offshore plants. Manual inspections of the offshore plants on a regular basis is not only time consuming but also dangerous regarding to human safety. For considering the safety measurement and alleviating the burden of the manual inspection, unmanned aerial vehicles (UAVs) can be effectively utilized to collect data from the remote industrial environment. In an industrial scenario, less delay is required for emergency packets and high throughput is needed for monitoring packets. This paper proposes a priority-aware fast MAC (PF-MAC) protocol for UAV-assisted industrial Internet-of-things (IIoT) systems, ensuring fast and robust data delivery. At first, the IoT devices under the UAV communication range transmit a reservation frame to the UAV to catch transmission opportunities using CSMA/CA. The devices utilize static traffic priority and a novel adaptive backoff mechanism during CSMA/CA. After receiving the reservation frames from the IoT devices, the UAV calculates the dynamic device priority based on their static traffic priority, communication duration, sampling frequency, and remaining energy. Then, time slot is assigned by the UAV to each device for data transmission. To ensure fairness, if a device fails in contention during the CSMA/CA period, the static traffic priority is raised in the next retransmission. There is no prior work in the literature that considers both the traffic priority and the device priority to ensure Quality of Service in IIoT and related systems. According to our performance study, the proposed PF-MAC outperforms the conventional protocols in terms of delay and throughput.

Improving TCP Performance over Mobile Ad Hoc Networks with an Adaptive Backoff and Response approach (Dept.E)

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Adaptive Backoff enabled WUR on non-cellular local IoT for extreme low power operation

A large number of edge devices employed for Internet of Things (IoT) technology require low-power operation to extend operating time. However, contention-based networks may cause channel collisions and throughput degradation as the number of devices increases. Furthermore, in a competition-based network in which different IoT devices coexist, one common channel access algorithm is required for effective spectrum access. Therefore, we propose an adaptive backoff enabled MAC operation of a common channel access algorithm for edge devices with different MAC protocols in a local IoT wireless environment to reduce power consumption and channel access latency. The discrete-event simulation results demonstrate that the proposed channel access scheme outperforms the existing EDCA channel access schemes in general MAC under different scenarios such as traffic load and packet arrival rate.

Optimized Adaptive Back off Algorithm for Static and Mobile Wireless Ad hoc Networks

In wireless ad hoc networks with stationary and portable nodules situation, planning a backoff procedure is decisive to evade impact and to increase the act of nodules. Majority of the Medium Access Control (MAC) etiquettes intended for ad hoc networks take up stationary nodules situation. In this paper, an Optimized Adaptive Backoff Algorithm (OABA) is proposed for static and mobile wireless ad hoc networks. In this algorithm, during the back off stage, the type of node is determined as static or mobile. For mobile nodes, their residence time is determined in addition to their priority. Then optimized adaptive backoff algorithm is applied, by checking the type of node. Simulation results have shown that OABA achieves higher delivery ratio with minimized delay, packet drop and energy consumption.

WLAN Aware Cognitive Medium Access Control Protocol for IoT Applications

Internet of Things (IoT)-based devices consist of wireless sensor nodes that are battery-powered; thus, energy efficiency is a major issue. IEEE 802.15.4-compliant IoT devices operate in the unlicensed Industrial, Scientific, and Medical (ISM) band of 2.4 GHz and are subject to interference caused by high-powered IEEE 802.11-compliant Wireless Local Area Network (WLAN) users. This interference causes frequent packet drop and energy loss for IoT users. In this work, we propose a WLAN Aware Cognitive Medium Access Control (WAC-MAC) protocol for IoT users that uses techniques, such as energy detection based sensing, adaptive wake-up scheduling, and adaptive backoff, to reduce interference with the WSN and improve network lifetime of the IoT users. Results show that the proposed WAC-MAC achieves a higher packet reception rate and reduces the energy consumption of IoT nodes.

Adaptive Transmission Control for Uplink/Downlink Fairness in Unsaturated CSMA Networks

In carrier sensing multiple access (CSMA)-based IEEE 802.11 systems, it is important for an access point (AP) and multiple stations to have access opportunity proportional to their traffic load, ensuring fairness between uplink (UL) and downlink (DL). This letter proposes an adaptive backoff algorithm based on estimation for the UL/DL backlog sizes in unsaturated CSMA networks. Based on the UL/DL backlog estimation, the optimal UL and DL transmission probabilities are derived as a function of the UL/DL backlog sizes. The proposed algorithm not only improves the overall system performance but also provides the near-perfect UL/DL fairness.

A Wake-up Radio protocol based on adaptive backoff and dynamic CCA in Wireless Sensor Networks

Asynchronous wake-up communication based on wake-up radio (WuR) is an important energy-saving method in wireless sensor networks (WSNs). The Clear Channel Assessment (CCA) is a major section of energy consumption in asynchronous WuR-based nodes. The traditional static backoff will lead to longer waiting delay which increase the energy consumption of successful sending packets when the network traffic becomes heavier. So a protocol DNAP-WuR is proposed to solve these problems in the terminal initiated (TI) communication mode. It first implements the dynamic CCA optimization (DCO) mechanism which allows nodes to interrupt the CCA process as soon as the channel is busy. Nodes can go to sleep faster during busy periods, instead of performing CCA detection until the counter is reduced to zero. And then, the WuR based adaptive logarithm backoff (WALB) algorithm is used to predict the backoff time sequences which can reduce the WuC’s collision probability and decrease the energy consumption according to the nodes number and the packet arrival rate. In order to avoid the phenomenon that the backoff window size is reduced too fast or increased slowly after packets transmitted. Compared with CSMA-WuR protocol, the DNAP-WuR has 4.6% reduction in energy consumption and 12.1% promotion in throughput.