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Coexistence between networks is an emerging challenge in the 60 GHz unlicensed band. An approximate analytical formulation of the saturated throughput of a cognitive IEEE 802.15.3c MAC in the directional contention access period (D-CAP) in the presence of contention time allocation period (CTAP) is presented in this paper. The analytical framework is formulated for N devices, including the pico-net...
This paper introduces a novel paradigm for designing the physical and medium access control (MAC) layers of mobile ad hoc or peer-to-peer networks formed by half-duplex radios. A node equipped with such a radio cannot simultaneously transmit and receive useful signals at the same frequency. Unlike in conventional designs, where a node's transmission frames are scheduled away from its reception, each...
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...
This paper focuses on wireless body area networks (WBAN) targeted for medical ICT applications. The studied network follows a typical IEEE 802.15.4 beacon-enabled star topology. We simulate the collection of medical data from patients using wireless sensors. Impulse radio ultra wideband (IR-UWB) is chosen as a physical layer technology, in compliance with the IEEE 802.15.4a standard. Two random access...
Cooperative communications achieve tremendous improvements in system performance. Meanwhile, it tends to change the conventional access and transmission schemes in wireless networks. Thus, CoopMAC is proposed and analyzed for fully connected WLANs. It improves the performance of the network dramatically by enabling additional collaboration from other nodes. However, how does it work in multi-hop Ad...
In wireless ad hoc networks, multiple access interference is the limiting factor for the overall system performance. The lack of any central control unit necessitates a careful joint design of both, the physical and the MAC layer. Two promising technologies that address this problem are power control based cross-layer design and multiuser detection based cross-layer design. While approaches in the...
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...
In this paper, we consider the problem of power level selections under an average power constraint in slotted ALOHA networks. In the network, each node chooses a power level from a pre-determined power level set based on a probability for each access attempt. The derivation of the probability for maximizing the throughput is difficult. In addition, nodes may not always obey the given algorithm in...
In this paper, we compare communication schemes in scenarios of interest for underwater networks where multiple nodes collaborate towards the accomplishment of a target detection and tracking task. We consider two specific cases: in Scenario 1, a mobile Autonomous Underwater Vehicle (AUV) i) collects data from a set of fixed sensors deployed on the seafloor or ii) transmits data to the same nodes...
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...
The employment of device monitoring, diagnosis and condition-based maintenance is one of the potential approaches for enhancing operational efficiency and reducing energy consumption of industrial machines. Industrial wireless sensor networks (IWSNs) for device monitoring are appealing to industry due to their inherent advantages compared with traditional wired systems, such as low cost, convenience...
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,...
The purpose of this paper is to demonstrate the advantages of receiver based interference protection for Medium Access Control (MAC) protocols in Wireless Sensor Networks (WSNs) and to present a two-hop protection scheme which can increase the probability of successful data packet transmission. In previous studies of MAC protocols for WSNs, hop based interference models are commonly used, and the...
In wireless local area networks, spatially varying channel conditions result in a severe performance discrepancy between different nodes in the uplink, depending on their position. Both throughput and energy expense are affected. Cooperative protocols were proposed to mitigate these discrepancies. However, additional network state information (NSI) from other nodes is needed to enable cooperation...
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...
Low duty cycle operation is a well-known mechanism used for achieving energy efficiency in wireless sensor networks (WSNs). Nodes under this concept work only for a small percentage of time and remain largely inactive to conserve energy. S-MAC, is a popular protocol designed specifically for WSNs with low duty cycle operation. At its inception, S-MAC has been designed for low traffic loads. In this...
Industrial networks based on IEEE 802.15.4 are spreading, even though the joint requirement on predictability and reliability from industrial applications is hard to fulfil in wireless networks, and the data rate of IEEE 802.15.4 is rather low. With the goal of providing real-time guarantees, with increased reliability and throughput, we propose two multichannel network architectures based on IEEE...
In this paper, we propose a new 802.16 Qos scheduling architecture based on GPSS, integrating some kinds of existing scheduling algorithms. Then we design a simulation experiment to validate the effectiveness of the Qos scheduling architecture using Anylogic. The simulation results prove the new QoS architecture is effective, which can not only meet the delay requirement of real time applications,...
Wireless sensor networks (WSNs) are becoming progressively more attractive for a variety of application areas, including industrial automation, Industrial control and monitoring, security, Asset tracking and supply chain management, intelligent agriculture and environmental sensing, Health monitoring, weather analysis, and variety of military scenarios. WSN designers are trying to extend network lifetimes...
In order to reduce power consumption, many previously proposed MAC protocols for wireless sensor networks (WSNs) use a periodical active/sleep scheme. However, this scheme may not adapt to varying traffic conditions. A new throughput-adaptive MAC protocol (TA-MAC) is proposed in this paper, where overhearing nodes try to notify nodes a few hops away about the current transmission, therefore the latter...
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