Browsing by Subject "Local area networks"

Now showing 1 - 8 of 8

Open Access
An approach to manage connectionless services in connection-oriented networks
(IEEE, 1996) Abdelatı, Muhammed; Arıkan, Erdal
In this work we propose a pricing scheme which serves as an instrument for managing connectionless services in connection-oriented communication networks. The scheme is able to allocate network bandwidth in a Pareto-optimal way that maximizes the total surplus. The key idea is to decompose the service provision procedure among three separate parties whose interactions are governed by a set of competitive pricing mechanisms.
Open Access
Cooperative underwater acoustic communications
(IEEE, 2013) Al-Dharrab, S.; Uysal, M.; Duman, T.
This article presents a contemporary overview of underwater acoustic communication (UWAC) and investigates physical layer aspects on cooperative transmission techniques for future UWAC systems. Taking advantage of the broadcast nature of wireless transmission, cooperative communication realizes spatial diversity advantages in a distributed manner. The current literature on cooperative communication focuses on terrestrial wireless systems at radio frequencies with sporadic results on cooperative UWAC. In this article, we summarize initial results on cooperative UWAC and investigate the performance of a multicarrier cooperative UWAC considering the inherent unique characteristics of the underwater channel. Our simulation results demonstrate the superiority of cooperative UWAC systems over their point-to-point counterparts. © 1979-2012 IEEE.
Open Access
Lattice dynamics and elastic properties of lanthanum monopnictides
(2008) Gökoǧlu G.; Erkişi, A.
In this study, first principles calculation results of the second order elastic constants and lattice dynamics of two lanthanum monopnictides, LaN and LaBi, which crystallize in rock-salt structure (B1 phase), are presented. Calculations were based on plane wave basis sets and pseudopotential methods in the framework of Density Functional Theory (DFT) with generalized gradient approximation. Elastic constants are calculated by tetragonal and orthorhombic distortions on cubic structure. Phonon dispersion spectra was constructed in the linear response approach of the Density Functional Perturbation Theory (DFPT). The complete phonon softening with negative frequencies and large elastic anisotropy were observed for LaN single crystal as a sign of the structural instability. The phonon dispersion curve for LaBi is typical for lanthanum monopnictides and does not show any anomalous physical property. The calculated structural quantities for both LaN and LaBi systems agree well with the available experimental and theoretical data. © 2008 Elsevier Ltd. All rights reserved.
Open Access
A novel queue-aware wireless link adaptation mechanism and its fixed-point analytical model
(SpringerOpen, 2015) Ozturk, O.; Akar, N.
A point-to-point (PTP) wireless link is studied that carries long-lived TCP flows and is controlled with active queue management (AQM). A cross-layer queue-aware adaptive modulation and coding (AMC)-based link adaptation (LA) mechanism is proposed for this wireless link to improve the TCP-level throughput relative to the case where AMC decisions are made based solely on the physical layer (PHY) parameters. The proposed simple-to-implement LA mechanism involves the use of an aggressive modulation and coding scheme (MCS) with high spectral efficiency and high block error rates when the queue occupancy exceeds a certain threshold, but otherwise a relatively conservative MCS with lower spectral efficiency and lower block error rates. A fixed-point analytical model is proposed to obtain the aggregate TCP throughput attained at this wireless link and the model is validated by ns-3 simulations. Numerical experimentation with the proposed analytical model applied to an IEEE 802.16-based wireless link demonstrates the effectiveness of the proposed queue-aware LA (QAWLA) mechanism in a wide variety of scenarios including cases where the channel information is imperfect. The impact of the choice of the queue occupancy threshold of QAWLA is extensively studied with respect to the choice of AQM parameters in order to provide engineering guidelines for the provisioning of the wireless link.
Open Access
On secrecy rate analysis of spatial modulation and space shift keying
(IEEE, 2015) Aghdam, Sina Rezaei; Duman, Tolga M.; Di Renzo, M.
Spatial modulation (SM) and space shift keying (SSK) represent transmission methods for low-complexity implementation of multiple-input multiple-output (MIMO) wireless systems in which antenna indices are employed for data transmission. In this paper, we focus our attention on the secrecy behavior of SSK and SM. Using an information-theoretic framework, we derive expressions for the mutual information and consequently compute achievable secrecy rates for SSK and SM via numerical evaluations. We also characterize the secrecy behavior of SSK by showing the effects of increasing the number of antennas at the transmitter as well as the number of antennas at the legitimate receiver and the eavesdropper. We further evaluate the secrecy rates achieved by SM with different sizes of the underlying signal constellation and compare the secrecy performance of this scheme with those of general MIMO and SIMO systems. The proposed framework unveils that SM is capable of achieving higher secrecy rates than the conventional single-antenna transmission schemes. However, it underperfoms compared to a general MIMO system in terms of the achievable secrecy rates.
Open Access
A scheme for handling connectionless services in connection-oriented networks
(The Institute of Electronics, Information and Communication Engineers, 1997-10-25) Abdelati, M.; Arikan, E.
In this work we propose a pricing scheme which serves as an instrument for managing connectionless services in connection-oriented communication networks. The scheme is able to allocate network bandwidth in a Pareto-optimal way that maximizes the total surplus. The key idea is to decompose the service provision procedure among three separate parties whose interactions are governed by a set of competitive pricing mechanisms.
Open Access
Wireless ATM: limits, challenges, and proposals
(Institute of Electrical and Electronics Engineers, 1996) Ayanoglu, E.; Eng, K. Y.; Karol, M. J.
Recently, there has been an increased interest in the topic of "wireless ATM." The subject matter raises interest due to the potential combination of two of the hottest topics in communications of the mid-'90s, but at the same time raises a natural question as to its viability, and sometimes even its desirability. In this article the authors survey potential applications of wireless ATM and describe what is usually meant by wireless ATM, why it may make sense, and some of the proposals to build systems based on it. The emphasis in this article is on the physical layer, the data link layer, and the access layer. The authors also present general observations on each of these layers, and some research solutions to these problems. Mobility issues and interoperability with the existing networks are addressed. Finally, the authors list some of the proposals to build wireless ATM systems from the literature.
Open Access
WiSAP: a wireless personal access network for handheld computing devices
(Institute of Electrical and Electronics Engineers, 1998) Bisdikian, C.; Bhagwat, P.; Gaucher, B. P.; Janniello, F. J.; Naghshineh, M.; Pandoh, P.; Korpeoglu, I.
New short-range wireless communication technologies would enable environment-aware, mobile, personal area networks. These new technologies will serve as enablers for ubiquitous, low-cost, low-complexity, small-sized information appliances. These appliances will serve as interaction tools between humans and computer-driven services and applications existing in either the close or distant vicinity of humans. In this article the new application paradigms these new technologies will enable are explored. Furthermore, an experimental wireless personal access networking platform called WiSAP, developed to research these new technologies and applications paradigms, is presented. Finally, some of the experiences gained from WiSAP while designing a consumer-oriented portable wireless communication system suitable for wireless mobile personal access networks are also presented.