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Multiple Accesses Broadcasting (MABC) is a spectral efficient protocol in two-way relay channel (TWRC). The drawback of this protocol in decode-and-forward (DF) mode is decoding complexity at the relay's side. Erroneous decoding at the relay can bring about error propagation that leads to performance degradation in all of the relay networks operating in the DF mode. In this paper, we propose ML detection...
A lot of college wireless networks use software systems and web-based logins to authenticate users. In this paper we find that it is not hard to bypass such authentication. An attacker can use DHCP request to collect information about the users on the network. It makes the attacker much easier to gain unauthorized access to the network facilities. This can be done by putting the network card on monitor...
This paper presents the work that is done embedded in the EEnergy project “E-DeMa” to simulate powerline communication systems (PLC) for access and inhouse applications in a smart grid scenario. The simulation is implemented in a C++ builder using OMNeT++ and its sub module INET. OMNeT is an event based network simulation tool, and INET is a collection of common network units and technologies, so...
We present the design and evaluation of a flexible UHF RFID reader that enables new PHY/MAC designs to be prototyped and evaluated. Our reader is built using the USRP software radio platform in conjunction with software we developed in the open-source GNU Radio framework. We believe it is the first inexpensive tool that readily enables changes to the physical and MAC layer of RFID systems. We evaluate...
Wireless communications for body area network (BAN) applications require an adaptable, dynamic and flexible medium access control (MAC) to cope with a variety of application requirements. The key requirements in BAN applications are low power consumption, high reliability of intra-BAN communication and low latency. As body posture highly affects the performance of MAC protocols, we evaluate the relaying...
This paper identifies a class of potential vehicular network applications that are geographically localized and restricted to groups of vehicles. Applications such as group voice or text chat, periodic location updates and rear-seat gaming require content to be published and consumed by group members. In this framework, content delivery performance is the key metric. In this paper, we study the performance...
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...
Joint optimization of network coding and Aloha-based medium access control (MAC) for multi-hop wireless networks is considered. The multicast throughput is maximized subject to flow conservation and MAC achievable rate constraints to obtain the optimal transmission probabilities. The resultant optimization problem is inherently non-convex and hence difficult to solve even in a centralized manner....
A 2D Markov-Chain analysis is used to model channel occupancy within a high mobility picocell based network including handover and outage events. Single-cell performance is evaluated by the Grade of Service and by the call dropping probability. The relations between different picocellular network parameters are analyzed and guidelines for proper MAC protocol design are given.
The medium access control being the main source of energy wastage in wireless sensor networks, energy-efficiency is always kept in mind while designing the communication stack. Especially, versatile preamble-sampling MAC protocols emerged to offer a suitable solution over multiple deployment characteristics. For instance, some works have targeted burst transmissions while others have focused on long-term...
In this paper, we discuss the challenges associated with integrating multiuser OFDMA in a single cell IEEE 802.11 based wireless ad hoc network and propose a new, dynamic and robust approach to improve it. Our new MAC, using OFDMA in the physical layer, can incorporate multiple concurrent transmissions or receptions in a dynamic manner and can adjust the collision probability based on the traffic...
Many modern wireless data networks employ Carrier Sense Multiple Access (CSMA) for efficient medium access. The p-persistent CSMA protocol is an analytically tractable version of CSMA that has been used successfully to model practical medium access protocols such as the IEEE 802.11 Distributed Coordination Function (DCF). We present a closed-form expression to characterize the access probabilities...
Radio Frequency Identification (RFID) devices depend on the correct operation of their memory for guaranteeing accurate identification and delivery of transponder's information. In this paper, a novel approach for online testing of RFIDs based on March-BIST techniques for EEPROMs is presented. Online test is achieved by modifying the transponder's operation and access protocol to exploit the waiting...
The current IEEE 802.11 Distributed Coordination Function (DCF) that provides equal medium access probability to all transmitters suffers from uplink and downlink imbalanced link problem when operating in the infrastructure mode. Therefore, this paper proposes an Enhanced High-performance Distributed Coordination Function (EHDCF) to mitigate this imbalanced link problem. In EHDCF, the current transmitting...
This paper addresses the problem of MAC performance evaluation of a contemporary IEEE 802.11 WLAN. The network is observed under saturation conditions and the packet transmission probability analysis is conducted with the novel regenerative approach. The proposed model accounts for collision resolution protocol parameters, packet retry limit, coexistence of unicast and broadcast traffic, and heterogeneous...
Recently, wireless protocols related to BAN (Body Area Networks) are under standardization by the IEEE 802.15 (Personal Area Networks, PAN) committee, to enable interoperability of a wide range of applications in the areas of medical support, healthcare monitoring and con sumer wellness electronics. BAN requirements are closely related to PAN or WSN (wireless sensor network) technologies; however...
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...
The function and structure and the architecture of sensor network based on ZigBee/802.15.4 standard for forest monitoring are designed in this paper. According to the features of forest monitoring, the sensor nodes based on CC2520 and low power consumption chip MSP430F5437 and the coordinator Combing with ARM are designed which realize the energy control in physical layer. With the wireless sensor...
Distributed Coordination Function (DCF) of IEEE 802.11 WLANs prohibits concurrent transmissions to avoid packet collisions or interferences. This conservative transmission mechanism of DCF makes it hard to fully utilize the wireless capacity in terms of spatial reuse. Recent measurement studies demonstrate that a packet can survive the collision and can be decoded successfully by the receiver depending...
This paper considers optical WDM multi-ring metro networks that can be used to support simultaneously multiple client layers. In each ring, time is slotted and Optical Packet Switching (OPS) is implemented thanks to an out of band control channel. Optical packets are thus transparently transmitted between any two nodes on a given ring. We propose here a novel MAC protocol that supports multiple client...
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