The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
As an alternative to radio-frequency (RF) communications, optical wireless communications (OWC) can support high data rates and low power operations while providing good jamming resistance. Our focus in this paper is on deep ultraviolet (UV) outdoor communications (UVOC) where solar blind and non-line-of-sight operations are attractive. Light beams from UV LED arrays serve as information carriers...
Wireless ad-hoc networking will be a fundamental component of emerging technologies such as multi-hop cellular networks, vehicular ad-hoc networks and wireless mesh networks, with most of these technologies based on evolved versions of the 802.11 standard. To achieve their expected benefits, and address their challenges, in terms of energy efficiency, reliability or reconfigurability, advanced cooperative...
Congestion in mobile ad hoc networks not only results in transmission delay and packet loss, but also degrades throughput. For effective congestion detection and control, accurate estimation of MAC overhead, packet retransmission, backoff interval and queuing delay is necessary. This paper proposes a congestion aware nodes (CAN) based scheme to control congestion in mobile ad hoc networks. In this...
The performance of traditional TCP congestion control protocol degrades when congestion and contention increase in ad hoc networks that use the IEEE 802.11 DCF. Many of the problems result from medium contention at the media access control (MAC) layer. In this paper, we present a new contention-based congestion control (CBCC) method according to a novel congestion information from MAC layer. This...
This work presents a distributed time slot assignment algorithm which adopts TDMA as Medium Access Control, specially suited to support applications with strict delay, jitter and throughput requirements characterized by convergecast traffic patterns in sensor networks. (E.g. wireless video surveillance sensor networks). Our algorithm has three characteristics: (1) Every node is guaranteed a path to...
In wireless multihop ad hoc networks, the hidden terminal problem severely degrades the overall performance. On the other hand, most existing solutions cause larger blocking areas and hence a more severe exposed-terminal problem. In this paper, we present a new Enhanced Busy-tone Multiple Access (EBTMA) medium access control (MAC) protocol. The proposed protocol minimizes the negative impact of both...
We consider the problem of designing cooperative driver assistance and collision warning systems in vehicular networks. In this problem each car has a small size state information message that should be received by its neighborhood within a short lifetime of L timeslots. Because of the safety nature of the application, communication reliability (success probability) and delay are of critical importance...
Communication between two neighboring nodes is the most basic operation in wireless networks. Yet very little research has focused on the local delay, defined as the mean time it takes a node to connect to a nearby neighbor. This problem is non-trivial when link distances are random but static, as is the case when the node distribution of a static network is modeled as a stochastic point process....
Optimal transmission policies for a two-user multiple access broadcast channel with binary feedback are investigated. The system is modeled as a dynamic team. Conditioned on the channel feedback, the past history of buffer states is redundant to each user. Once this redundant data is removed, the information structure, although non-classical, satisfies the sufficient conditions of Mahajan, Nayyar,...
In this paper, we investigate the training problem of wireless local area networks (WLANs) with downlink multi-user multiple input multiple output (DL MU MIMO) capability. We extend the 802.11 MAC protocol and propose a few training protocols at the MAC layer to support DL MU MIMO. We provide a capacity analysis based on measurement results from an 802.11n systems, evaluate the overhead of these training...
IEEE 802.11 Wireless Local Area Network (WLAN) Physical Layer (PHY) offers multiple data rates. In multi-rate WLANs, 802.11 Medium Access Control (MAC) protocol, Distributed Coordination Function (DCF), essentially provides equal transmission opportunities to each sender host, causing the degradation of system throughput due to some hosts using low rates. In this paper we propose a cross-layer link...
Due to the license-exempt nature of the cognitive radio (CR), multiple CR networks may operate (coexist) on the same channel. In this paper, we first discuss some techniques for self-coexistence of CR local and personal area networks, where the self-coexistence means the coexistence of homogeneous CR networks using the same PHY/MAC protocol. Then, we propose a self-coexistence etiquette for the ECMA...
This paper addresses the fairness of Medium Access Control (MAC) protocols that are capable of handling interference on the physical layer to a varying extent. The variation addressed is thereby not based on different physical layer techniques applied, but on differing attribute levels of the same physical layer technique. This can e.g., be a varying number of antennas at each node in case of Multiple...
This paper introduces a technology convergence adaptor for a previously presented Inter-MAC architecture for heterogeneous home area networks. Its main task is to translate technology-dependent link metrics into a machine readable common language. This language allows for the description of various service and application classes and provides means to describe link metrics of underlying MAC protocols...
Underwater communication mainly relies on acoustic waves. Its unique characteristics, such as slow propagation speed and low bit rate-distance product, present both challenges and opportunities for Media Access Control (MAC) protocol design. In existing sender-initiated handshaking based MAC protocols, each successful handshake only allows an initiating sender to transmit single or multiple consecutive...
Wireless Body Area Network (WBAN) allows the integration of low-power, miniaturized, intelligent, invasive or/and non-invasive wireless sensor nodes that are used to monitor the health status of a patient with real-time updates to a base-station/physician. Since multiple low-power sensor nodes are deployed in/on a human body, Medium Access Control (MAC) protocols are required to share the channel...
In this paper, we examine the effect of retransmission cutoff in slotted ALOHA systems employing the binary exponential backoff (BEB) algorithm, in terms of throughput and delay performance, system stability and packet dropping probability. For comparison, the performance of the BEB algorithm without retransmission cutoff is presented. We consider a finite population of users competing for channel...
In this paper we analyzed the principle of an Adaptive Random-Reservation Medium Access Control (MAC) protocol in Sat-ATM Network which can support almost all ATM service classes, emphasizes the adaptive random-reservation MAC protocol with its performance evaluated through simulation. The result indicates that the TDMA based Adaptive Random-Reservation MAC protocol can maximize the utilization of...
We present an orthogonal frequency division multiple access (OFDMA) cognitive radio medium access control using multichannel ALOHA (OCR MAC). The performance of an infinite population based OCR system is numerically as well as theoretically analyzed in terms of throughput, delay, and data capacity. We evaluate the throughput versus delay tradeoff of OCR MAC with an agile OFDM channel selection. Especially,...
Wireless communication has become the fastest growing area in the communication industry. The demand for using this medium ranges from security, military, Internet and scientific purposes and are rapidly replacing wire-line systems in many developing countries. Wireless Sensor Networks (WSN) is currently a research area that is being studied by many researchers and industries within the wireless communication...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.