A Novel QoS-Aware A-MPDU Aggregation Scheduler for Unsaturated IEEE802.11n/ac WLANs

Improving the quality of service (QoS) performance to support existing and upcoming real-time applications is critical for IEEE 802.11n/ac devices. The mechanisms of the media access control (MAC) layer, including the aggregate MAC protocol data unit (A-MPDU) aggregation, greatly affect the QoS performance in wireless local area networks (WLANs). To investigate the impact of the aggregation level on the QoS performance for real-time multimedia applications, a novel end-to-end delay model for the unsaturated settings is proposed in this paper. The presented model considers the gathering procedure of packets, queuing behaviors, and transmissions using the RTS/CTS (request to send/clear to send) mechanism on error-prone channels. Based on the model, a novel QoS-aware A-MPDU aggregation scheduler for IEEE802.11n/ac WLANs was shown to obtain better QoS performance with lower latency and less packet loss, a larger capacity to hold higher data rates, and more working nodes. The validation of the proposed model and the promotion of the proposed scheduler are well benchmarked by ns-3.

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Fairness Oriented Neighbor-Channel-Aware MAC Protocol for Airborne Sensor Networks

10.20944/preprints201703.0041.v1 ◽

2017 ◽

Author(s):

Xiaolin Gao ◽

Jian Yan ◽

Jianhua Lu

Keyword(s):

Sensor Networks ◽

Mac Protocol ◽

Traffic Load ◽

Media Access Control ◽

Media Access ◽

Traffic Loading ◽

Protection Mechanism ◽

Traffic Loads ◽

The Media ◽

Inter Frame

In airborne sensor networks (ASNs), the media access control (MAC) protocol is facing with serious unfairness problem due to the traditional protection mechanism of air-to-air communications among aircrafts. Actually by using the binary exponential back-off algorithm at high traffic loads to minimize collisions among users, the latest successful node can always benefit from this kind of MAC to obtain channel resources. Moreover, when taking the existence of the hidden nodes in ASNs into account, the inaccurate traffic load information will further aggravate the system’s unfairness. In this paper, a neighbor-channel-aware (NCA) protocol is proposed to improve the fairness of MAC protocol in ASNs. In the proposal, the NCA frame is firstly added and exchanged between neighbor nodes periodically, which helps to resolve the inaccurate traffic load information, so as to avoid reducing the probability of successful message transmission. Then a traffic-loading based back-off algorithm is involved to make the neighbor nodes cooperatively adjust the inter-frame space (IFS) interval to further reduce the unfairness. The simulation results show that, the proposed MAC protocol can guarantee the satisfied fairness, simultaneously avoiding heavy network overloads to protect key messages’ successful transmissions in ASNs.

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A QoS Based Adaptive Backoff Scheme for Vehicular Ad Hoc Networks

Sensors ◽

10.3390/s18124421 ◽

2018 ◽

Vol 18 (12) ◽

pp. 4421 ◽

Cited By ~ 1

Author(s):

Tianjiao Zhang ◽

Qi Zhu

Keyword(s):

Ad Hoc Networks ◽

Network Performance ◽

Vehicular Ad Hoc Networks ◽

Ad Hoc ◽

Intelligent Transportation System ◽

Mac Protocol ◽

Media Access Control ◽

Media Access ◽

The Media ◽

Hoc Networks

The media access control (MAC) protocol is a key element in the design of vehicular ad hoc networks (VANETs) that directly affects the network performance. The backoff schemes of existing MAC protocols apply the single backoff process and therefore are not suitable for multi-class data transmission. Additionally, they cannot satisfy the delay requirements of emergency data in the case of varying number of vehicles, causing an adverse effect to the intelligent transportation system (ITS). This paper presents a priority-based adaptive backoff scheme that can enhance the binary exponential backoff (BEB) algorithm as well as the polynomial backoff (QB) algorithm. This system distinguishes priority data with different delay requirements first and designs different backoff schemes for each type of data later. The two-dimensional Markov Chain is used to analyze the backoff scheme and determine the expressions for throughput and delay. The simulation results show that the backoff scheme provided by this paper can reduce the average data delay and regulate each kind of data delay adaptively, according to the varying number of vehicles and different delay requirements.

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Full-Duplex MAC Protocol for CSMA/CA-Based Single-Hop Wireless Networks

Sensors ◽

10.3390/s19102413 ◽

2019 ◽

Vol 19 (10) ◽

pp. 2413 ◽

Cited By ~ 1

Author(s):

Yu Song ◽

Wangdong Qi ◽

Weiwei Zhao ◽

Wenchi Cheng

Keyword(s):

Mac Protocol ◽

Transmission Probability ◽

Full Duplex ◽

System Throughput ◽

Media Access Control ◽

Media Access ◽

Half Duplex ◽

Long Time ◽

The Media ◽

The One

Full-duplex (FD) communication provides new opportunities for improving the throughputs of networks. However, this condition means that the number of senders increases from one to two within a certain range. We have to arrange the two nodes to send frames simultaneously in the media access control (MAC) layer. For the single-hop network model, using the FD features of the nodes and the cut-through mechanism, we propose an FD MAC protocol. The protocol improves the throughput of the network from the following two aspects. On the one hand, during the transmission of each node, based on the information of the received frame’s header, the protocol can detect collisions in the network, preventing the channel from being ineffectively occupied for a long time. On the other hand, the protocol can provide the FD with as many opportunities as possible for the nodes. According to the working process of the protocol, we modeled the states (“active” and “passive” transmission, back-off) of each node and their transitions to a Markov chain. We solved the “active” transmission probability of the node and further modeled the analytical performance of the protocol. The simulation results showed that the system throughput produced by our protocol was at least twice that of the conventional CSMA/CA protocol used in the half-duplex networks.

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Reactive GTS Allocation Protocol for Sporadic Events Using the IEEE 802.15.4

Mathematical Problems in Engineering ◽

10.1155/2014/836524 ◽

2014 ◽

Vol 2014 ◽

pp. 1-13

Author(s):

Mukhtar Azeem ◽

Majid I. Khan ◽

Yasir Faheem ◽

Manzoor Illahi Tamimy ◽

Najmus Saqib Malik ◽

...

Keyword(s):

Real Time ◽

Ieee 802.15.4 ◽

Industrial Applications ◽

Media Access Control ◽

Media Access ◽

Control Protocol ◽

Periodic Schedule ◽

The Media ◽

Ieee 802.15.4 Standard ◽

Random Nature

Wireless sensor networks (WSNs) find applications in the industrial automation where periodic and sporadic events occur. The combined propagation of information generated by periodic and sporadic events from a sensor node to an actuator node is challenging due to random nature of sporadic events, particularly, if the deadlines are hard. The IEEE 802.15.4 standard provides the basis for a real-time communication mechanism between neighboring nodes of the WSN at the media access control layer. However, the standard does not address such communications over multiple hops. To support the industrial applications with such requirements, this work proposes a novel online control protocol that exploits the basis provided by the IEEE 802.15.4 standard. The proposed control protocol ensures that a given offline sporadic schedule can be adapted online in a timely manner such that the static periodic schedule has not been disturbed and the IEEE 802.15.4 standard compliance remains intact. The proposed protocol is simulated in OPNET. The simulation results are analyzed and presented in this paper to prove the correctness of the proposed protocol regarding the efficient real-time sporadic event delivery along with the periodic event propagation.

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The Process of Globalization and Its Impact on Media

European Journal of Multidisciplinary Studies ◽

10.26417/ejms.v1i4.p150-153 ◽

2016 ◽

Vol 1 (4) ◽

pp. 150

Author(s):

Veton Zejnullahi

Keyword(s):

New Technology ◽

World Order ◽

Modern Society ◽

Media Access ◽

Four Corners ◽

The World ◽

The Media ◽

The Republic ◽

Human Eyes ◽

The Impact

The process of globalization, which many times is considered as new world order is affecting all spheres of modern society but also the media. In this paper specifically we will see the impact of globalization because we see changing the media access to global problems in general being listed on these processes. We will see that the greatest difficulties will have small media as such because the process is moving in the direction of creating mega media which thanks to new technology are reaching to deliver news and information at the time of their occurrence through choked the small media. So it is fair to conclude that the rapid economic development and especially the technology have made the world seem "too small" to the human eyes, because for real-time we will communicate with the world with the only one Internet connection, and also all the information are take for the development of events in the four corners of the world and direct from the places when the events happen. Even Albanian space has not left out of this process because the media in the Republic of Albania and the Republic of Kosovo are adapted to the new conditions under the influence of the globalization process. This fact is proven powerful through creating new television packages, written the websites and newspapers in their possession.

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IEEE 802.11 Tutorial

10.31224/osf.io/t8rjk ◽

2018 ◽

Author(s):

Kiramat

Keyword(s):

Access Control ◽

Ieee 802.11 ◽

Wireless Local Area Network ◽

Local Area Network ◽

Local Area ◽

Physical Layer ◽

Media Access Control ◽

Area Network ◽

Media Access ◽

Computer Communications

IEEE 802.11 is a set of media access control (MAC) and physical layer (PHY) specifications for implementing wireless local area network (WLAN) computer communications. Maintained by the Institute of Electrical and Electronics Engineers (IEEE) LAN/MAN Standards Committee (IEEE 802). This document highlights the main features of IEEE 802.11n variant such as MIMO, frame aggregation and beamforming along with the problems in this variant and their solutions

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