Game theoretic approach in routing protocol for wireless ad hoc networks

This paper introduces a game theoretic method, called forwarding dilemma game (FDG), which controls routing overhead in dense multi-hop wireless ad hoc networks. The players of the game are the wireless nodes with set of strategies {Forward, Not forward}. The game is played whenever an arbitrary node in the network receives a flooding packet. In FDG, every player needs to know the number of players of the game. That is why a neighbor discovery protocol (NDP) is introduced. In order for NDP to function, a field is attached to the flooding packets (routing overhead packets). The mixed strategy Nash equilibrium is used as a solution for the FDG. This provides the probability that the flooding packet would be forwarded by the receiver node. FDG with NDP is implemented in AODV protocol in Network Simulator NS-2 to verify its performance with simulations. FDG with NDP improves performance of the AODV compared to the same network with only AODV protocol in moderate and high node densities. FDG can be applied to any routing protocol that uses flooding in the route discovery phase

A novel real-time MAC layer protocol for wireless sensor network applications

This paper presents a comparative study of existing real-time MAC layer protocols for wireless sensor networks. Then, a new real-Time MAC protocol is presented that is based on a general purpose MAC protocol, called S-MAC. While medium access strategy in S-MAC is based on contention and back-off schemes, protocol proposed in this paper uses feedback approach as a medium access strategy. As a result of this, it increases consistency in data transmission pattern, which enables it to guarantee end-to-end delay deadlines for soft realtime applications. Proposed protocol works in continuous ON mode of operation at MAC layer and is intended to be used for randomly deployed single stream wireless sensor applications. Finally, a comparative performance analysis of proposed realtime protocol is done with other real-time and general purpose MAC protocols for wireless sensor networks

Applying Unbalanced RSA to Authentication and Key Distribution in 802.11

It is well known that the data confidentiality algorithm, called Wired Equivalent Privacy (WEP), offerred by the original IEEE 802.11 is not secure mainly due to its improper implementation of RC4 algorithm [3], [4]. The IEEE 802.11 Task Group ’I’ (TGi) has designed two options to address this problem. One is called Temporal Key Integrity Protocol (TKIP), intended to be used as a short-term patch for currently deployed equipment. The other one uses Advanced Encryption Standard (AES), a powerful block cipher recommended by NIST to replace DES in 2000, as a long-term solutio

An automatic calibration method for stereo-based 3D distributed smart camera networks

Stereo-based 3D distributed smart camera networks are useful in a broad range of applications. Knowledge of the relative locations and orientations of nodes in the network is an essential prerequisite for true 3D sensing. A novel spatial calibration method for a network of pre-calibrated stereo smart cameras is presented, which obtains pose estimates suitable for collaborative 3D vision in a distributed fashion using two stages of registration on robust 3D point sets. The method is initially described in a geometrical sense, then presented in a practical implementation using existing vision and registration algorithms. Experiments using both software simulations and physical devices are designed and executed to demonstrate performance

Design and Implementation of a Testbed for IEEE 802.15.4 (Zigbee) Performance Measurements

IEEE 802.15.4, commonly known as ZigBee, is a Media Access Control (MAC) and physical layer standard specifically designed for short range wireless communication where low rate, low power, and low bandwidth are required. This makes ZigBee an ideal choice when it comes to sensor networks for monitoring data collection and/or triggering process responses. However, these very characteristics bring into question ZigBee\u27s ability to perform reliably in harsh environments. This paper thoroughly explains the experimental testbed setup and execution to demonstrate ZigBee\u27s performance in several practical applications. This testbed is capable of measuring the minimum, maximum, and average received signal strength indicator (RSSI), bit error rate (BER), packet error rate (PER), packet loss rate (PLR), and the bit error locations. Results show that ZigBee has the potential capabilities to be used in all four tested environments

Feature-based calibration of distributed smart stereo camera networks

A distributed smart camera network is a collective of vision-capable devices with enough processing power to execute algorithms for collaborative vision tasks. A true 3D sensing network applies to a broad range of applications, and local stereo vision capabilities at each node offer the potential for a particularly robust implementation. A novel spatial calibration method for such a network is presented, which obtains pose estimates suitable for collaborative 3D vision in a distributed fashion using two stages of registration on robust 3D features. The method is initially described in a geometrical sense, then presented in a practical implementation using existing vision and registration algorithms. The method is designed independently of networking details, making only a few basic assumptions about the underlying networkpsilas capabilities. Experiments using both software simulations and physical devices are designed and executed to demonstrate performance

Competitive learning techniques for color image segmentation

A method for color image segmentation using a competitive learning clustering scheme is examined, and some basic improvements are made. Two important aspects of the color image segmentation problem, namely color space selection and over segmentation, are discussed in the context of the algorithm, with comments about suitability and effectiveness of choices for various applications. A variety of settings are tested and compared to highlight performance

Routing protocols for self-organizing hierarchical ad-hoc wireless networks

—A novel self-organizing hierarchical architecture is proposed for improving the scalability properties of adhoc wireless networks. This paper focuses on the design and evaluation of routing protocols applicable to this class of hierarchical ad-hoc networks. The performance of a hierarchical network with the popular dynamic source routing (DSR) protocol is evaluated and compared with that of a conventional “flat” ad-hoc networks using an ns-2 simulation model. The results for an example sensor network scenario show significant capacity increases with the hierarchical architecture (∼4:1). Alternative routing metrics that account for energy efficiency are also considered briefly, and the effect on user performance and system capacity are given for a specific example

Screening of the antioxidant activity of essential oil and various extracts of Origanum rotundifolium Boiss. from Turkey

This study is designed to examine the chemical composition and in vitro antioxidant activity of the essential oil and various extracts of Origanum rotundifolium Boiss. from Turkey. The total of the 40 identified components accounted for 97.23% (GC) and 95.10% (FID) of the total oil. Major components of the oil were borneol, terpinen-4-ol, and spathulenol. To determine the presence of well known and widespread phenolic compounds, water-soluble extract of O. rotundifolium was analyzed by HPLC. In the methanol-soluble extract, caffeic acid, p-coumaric acid, (+)-catechin, and ferulic acid were found in several quantities. Antioxidant activity of the essential oil and extracts of O. rotundifolium has been determined by four different test systems namely DPPH, β β β β-carotene/linoleic acid, chelating effect and reducing power. A strong correlation was observed between the radical scavenging capacity and polarity of the extracts. The methanol-soluble extract which contains the most polar phytochemicals showed the strongest antioxidant effect in all test systems. As expected, amount of the total phenolics and flavonoids was very high in methanol-soluble extract

Volume CXIV, Number 4, November 7, 1996

Objective: Turner syndrome (TS) is a chromosomal disorder caused by complete or partial X chromosome monosomy that manifests various clinical features depending on the karyotype and on the genetic background of affected girls. This study aimed to systematically investigate the key clinical features of TS in relationship to karyotype in a large pediatric Turkish patient population.Methods: Our retrospective study included 842 karyotype-proven TS patients aged 0-18 years who were evaluated in 35 different centers in Turkey in the years 2013-2014.Results: The most common karyotype was 45,X (50.7%), followed by 45,X/46,XX (10.8%), 46,X,i(Xq) (10.1%) and 45,X/46,X,i(Xq) (9.5%). Mean age at diagnosis was 10.2±4.4 years. The most common presenting complaints were short stature and delayed puberty. Among patients diagnosed before age one year, the ratio of karyotype 45,X was significantly higher than that of other karyotype groups. Cardiac defects (bicuspid aortic valve, coarctation of the aorta and aortic stenosis) were the most common congenital anomalies, occurring in 25% of the TS cases. This was followed by urinary system anomalies (horseshoe kidney, double collector duct system and renal rotation) detected in 16.3%. Hashimoto's thyroiditis was found in 11.1% of patients, gastrointestinal abnormalities in 8.9%, ear nose and throat problems in 22.6%, dermatologic problems in 21.8% and osteoporosis in 15.3%. Learning difficulties and/or psychosocial problems were encountered in 39.1%. Insulin resistance and impaired fasting glucose were detected in 3.4% and 2.2%, respectively. Dyslipidemia prevalence was 11.4%.Conclusion: This comprehensive study systematically evaluated the largest group of karyotype-proven TS girls to date. The karyotype distribution, congenital anomaly and comorbidity profile closely parallel that from other countries and support the need for close medical surveillance of these complex patients throughout their lifespa