Delay and collision reduction in wireless networks
Date
2020
Authors
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Journal ISSN
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Publisher
University of Delaware
Abstract
With the ever-increasing wireless data demand and limited wireless spectrum resources, to increase the capacity of wireless networks and to make more efficient use of the wireless spectrum have become two key challenges. On the one hand, new technologies are invented to increase the data rate and capacity of wireless networks. On the other hand, new data-hungry applications (e.g., interactive high-resolution video games and augmented and virtual reality) and delay-sensitive applications (e.g., real-time voice over IP and virtual reality) need more bandwidth and more frequent channel access, respectively. Medium access control (MAC) protocols located at the second layer of the Internet protocol stack (i.e., Link layer) are responsible for coordinating transmissions of different wireless stations to reduce end-to-end delay, collisions, and battery consumption, and to increase the overall throughput of the wireless networks. Since different layers of the Internet protocol stack are isolated from each other (to facilitate innovation in each layer separate from the others), when a new wireless communication technology requires enhancements in some criteria, new MAC protocols can be designed to address the needs. ☐ In this dissertation, we design new MAC protocols for different wireless communication technologies so as to reduce the collision and end-to-end delay among stations while increasing the overall throughput of the wireless network. To that end, we develop innovative access mechanisms, scheduling techniques, and architectures, and with simulations, measure the performance of networks working with these protocols based on the popular metrics of throughput, delay, and jitter among others. Finally, we compare the performance of the proposed protocols with state-of-the-art solutions. ☐ For wireless local area networks (WLANs), since the scheduling of packet transmissions solely relies on the collision and/or success a station may experience, we propose a distributed reservation mechanism for the Carrier Sense Multiple Access Extended Collision Avoidance (CSMA/ECA) MAC protocol, termed CSMA/ECA-DR. In CSMA/ECA-DR, stations collaboratively achieve higher network performance by avoiding anticipated collisions. In addition, proper Contention Window (CW) size will be chosen based on the instantaneously estimated number of active contenders in the network. Moreover, as the technology of full-duplex (FD) wireless communications (transmit/receive at the same time on the same frequency) has become feasible, and is orthogonal to other technologies in terms of increasing the capacity of wireless networks, we design a novel FD MAC protocol based on CSMA/ECA-DR. ☐ Furthermore, a new standard of IEEE 802.11 (i.e., WLAN), 802.11ax, has been standardized in late 2019. The new standard incorporates the technology of orthogonal frequency-division multiple access (OFDMA) to reduce collisions among stations and better satisfy the quality of service (QoS) for different types of traffic. Although OFDMA is not a new technology, due to intricacies associates with OFDMA usage in IEEE 802.11ax, new MAC scheduling algorithms are required to work with this Wi-Fi standard. We design a station selection algorithm and a scheduler for 802.11ax that can satisfy QoS requirements of different traffic types even in dense deployments. We further enhance the designed mechanisms to support virtual reality (VR) applications with IEEE 802.11ax. ☐ For underwater acoustic networks (UANs), we study the problem of energy-efficient acoustic networking. In addition, we design a new hybrid architecture that can increase the throughput while reducing the end-to-end delay between different pairs of autonomous underwater vehicles (AUVs). Furthermore, we design an FD MAC protocol that is capable of multi-targeted transmissions and adjusting transmitting power based on distances between nodes.
Description
Keywords
802.11ax Scheduling, AR/VR over 802.11ax, Deterministic backoff, Full-Duplex MAC, Hybrid RF Acoustic, Underwater Acoustic Sensor Networks