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.
Distributed medium access control protocols can be classified into contention-based and contention-free protocols. In this paper, we analyse a contention-free distributed protocol where nodes make reservations on a first-come first-served basis. We evaluate the impact of this first-come first-served approach on the fairness regarding throughput and delay, by means of the ECMA-368. This standard establishes...
Electronic services (mail, web, etc.) can operate, at present over wireless networks. 802.11 networks are an example, where wireless devices use its resources to access to networks and services and in particular to Internet. The security mechanisms in the MAC layer are added to existing security mechanisms in other layers of the TCP/IP model, and therefore it generates multiple encryption of information...
For wireless LANs, such as IEEE 802.11 networks, the channel utilization efficiency, the system stability, and the fairness of bandwidth allocation are three important criteria for designing medium access control (MAC) protocols. This paper aims to design a simple access mechanism optimized for all the aforementioned issues from a game theoretic perspective. In particular, this paper enables nodes...
The main objective of the MAC protocol in IEEE 802.11 standard is to access and control the shared limited bandwidth medium efficiently and fairly among all nodes. A maximum throughput is difficult to achieve due to the limited bandwidth of the wireless ad hoc networks, packet overhead, and hidden and the exposed terminal problems. The use of NACK control packets instead of ACKs can minimize network...
The IEEE 1609.4 standard has been proposed to provide multi-channel operations in wireless access for vehicular environments (WAVE), where all the channels are periodically synchronized into control and service intervals. The communication device in each vehicle will stay at the control channel for negotiation and contention during the control interval, and thereafter switch to one of the service...
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...
This paper discusses the delay characteristics and packet drop ratio performance of Busy Tone Multiple Access Protocol (BTMAP) for distances up to 48Km in IEEE 802.11 networks. The impact of the Contention Window (CW) is discussed. We note that a larger CW will increase the mean packet delay but decrease the packet drop ratio. Long range also significantly degrades the delay and packet drop ratio...
A lot of researches on IEEE 802.11 had been done, particularly on the performance analysis and improvement of DCF mechanism. However most of the studies were only on some aspect and lacked of systemic. On the other hand, the scenarios in previous' studies were mostly in ad hoc network only few in the network with infrastructure. This paper analyzed the IEEE 802.11 completely and systematically in...
In the last years the number of papers related to wireless sensor networks has increased substantially. Most of them focus in raising issues as routing algorithms, network lifetime, and more recently, Multiple Input Multiple Output wireless networks. In contrast with all those studies, we present a practical application of wireless networks: The sensing of the pH and temperature for a fish farm. The...
A schedule-based approach, such as TDMA, is more efficient than a Contention-based approach in terms of energy saving by switching sensors into sleeping mode. However it does not use the transmission media effectively as each timeslot is dedicated to a sensor and therefore cannot be used by others should it be idle. Moreover a schedule-based approach requires a central node to manage and broadcast...
Mobile nodes in a MANET incur much overload having to forward the packets of the adjacent nodes. Each node is expected to behave within the boundaries delineated by the underlying protocol. Each node in a MANET is expected to wait for a pre specified time interval generally termed as the back off interval. This back off interval is supposed to be chosen from a range, at random. But some nodes in an...
The TETRA system provides an authentication service which permits only the authorized terminal to access its network by verifying that the terminal equipment and the authentication center have the identical authentication key using challenge-response protocol. However, while TETRA standard authentication protocol is able to block cloned terminals that have cloned a terminal identifier called Individual...
Since its birth wireless communication became an indispensible part of the modern society. One major area that has a gigantic impact on the performance of wireless sensor networks (WSNs) is the Medium Access Control (MAC) layer. Many random access protocols exist in wireless sensor networks. Some of these protocols include Carrier Sense Multiple Access (CSMA), Multiple Access with Collision Avoidance...
In this paper, the effective channel usage is investigated in IEEE 802.11p WAVE (wireless access in vehicular environments) communication protocol. IEEE PI609 family is the standard for wireless access in vehicular environments based on IEEE 802.11p, and the WAVE architecture with multi-channel operation over CCH (control channel) and SCH (service channel) are defined in the MAC layer. However, there...
Channel condition is considered an important issue that affects the performance in wireless networks. Link Adaptation techniques have been proposed to improve the degraded network performance by adjusting the design parameters, e.g. the modulation and coding schemes, in order to adopt the dynamically changing channel conditions. Furthermore, due to the advancement of the IEEE 802.11n standard, the...
Fountain codes constitute novel erasure codes, which have been standardized for Forward Error Correction (FEC) in broadcast network protocols and by the Third-Generation Partnersonhip Project (3 GPP). The basic operational units of Fountain codes are source packets, which have a particular fixed length. These codes are invoked here in an 802.11 Wireless Local Area Network (WLAN) scenario for protecting...
The IEEE 802.17 is a standardized ring topology network architecture, called the resilient packet ring (RPR), to be used mainly in metropolitan and wide area networks. This paper focuses on the RPR MAC client implementation of the IEEE 802.17 RPR MAC in the aggressive mode of operation and introduces a new active queue management scheme for ring networks that achieves higher overall utilization of...
We present a covert side channel technique that uses the 802.11 MAC rate switching protocol as cover for covert authentication messages. Covert authentication prevents an attacker from knowing when a user is authenticating and protects user credentials from malicious software attacks. Similar to port knocking, a remote client sends authentication messages to an access point in order to access a protected...
Future active-safety applications in vehicular networks rely heavily on the support for real-time inter-vehicle communication. The medium access control (MAC) mechanism proposed for the upcoming IEEE 802.11p standard intended for intelligent transport systems (ITS) applications does not offer deterministic real-time support, i.e., the channel access delay is not upper bounded. We therefore propose...
In original 802.11 infrastructure network, a station (STA) is not allowed to transmit frames directly to other STAs within range. Frame delivery should rely on access point (AP) because recipients may be in power save mode and must be woke up before transmission. To allow direct transmission, 802.11e defines a new operation called direct link set-up (DLS). In DLS, STA can initiate a direct link through...
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.