A Tight Lower Bound to the Outage Probability of Discrete-Input Block-Fading Channels

In this correspondence, we propose a tight lower bound to the outage probability of discrete-input Nakagami-m block-fading channels. The approach permits an efficient method for numerical evaluation of the bound, providing an additional tool for system design. The optimal rate-diversity trade-off for the Nakagami-m block-fading channel is also derived and a tight upper bound is obtained for the optimal coding gain constant.Comment: 22 pages, 4 figures. This work has been accepted for IEEE Transactions on Information Theory and has been presented in part at the 2007 IEEE International Symposium on Information Theory, Nice, France, June 200

Neutron transition strengths of 21+2^+_1 states in the neutron rich Oxygen isotopes determined from inelastic proton scattering

A coupled-channel analysis of the $^{18,20,22}$O$(p,p')$ data has been performed to determine the neutron transition strengths of 2$^+_1$ states in Oxygen targets, using the microscopic optical potential and inelastic form factor calculated in the folding model. A complex density- and \emph{isospin} dependent version of the CDM3Y6 interaction was constructed, based on the Brueckner-Hatree-Fock calculation of nuclear matter, for the folding model input. Given an accurate isovector density dependence of the CDM3Y6 interaction, the isoscalar ($\delta_0$) and isovector ($\delta_1$) deformation lengths of 2$^+_1$ states in $^{18,20,22}$O have been extracted from the folding model analysis of the $(p,p')$ data. A specific $N$-dependence of $\delta_0$ and $\delta_1$ has been established which can be linked to the neutron shell closure occurring at $N$ approaching 16. The strongest isovector deformation was found for 2$^+_1$ state in $^{20}$O, with $\delta_1$ about 2.5 times larger than $\delta_0$, which indicates a strong core polarization by the valence neutrons in $^{20}$O. The ratios of the neutron/proton transition matrix elements ($M_n/M_p$) determined for 2$^+_1$ states in $^{18,20}$O have been compared to those deduced from the mirror symmetry, using the measured $B(E2)$ values of 2$^+_1$ states in the proton rich $^{18}$Ne and $^{20}$Mg nuclei, to discuss the isospin impurity in the $2^+_1$ excitation of the $A=18,T=1$ and $A=20,T=2$ isobars.Comment: Version accepted for publication in Physical Review

Nano strain-amplifier: making ultra-sensitive piezoresistance in nanowires possible without the need of quantum and surface charge effects

This paper presents an innovative nano strain-amplifier employed to significantly enhance the sensitivity of piezoresistive strain sensors. Inspired from the dogbone structure, the nano strain-amplifier consists of a nano thin frame released from the substrate, where nanowires were formed at the centre of the frame. Analytical and numerical results indicated that a nano strain-amplifier significantly increases the strain induced into a free standing nanowire, resulting in a large change in their electrical conductance. The proposed structure was demonstrated in p-type cubic silicon carbide nanowires fabricated using a top down process. The experimental data showed that the nano strain-amplifier can enhance the sensitivity of SiC strain sensors at least 5.4 times larger than that of the conventional structures. This result indicates the potential of the proposed strain-amplifier for ultra-sensitive mechanical sensing applications.Comment: 4 pages, 5 figure

Energy Consumption of Wireless Network Access Points

2nd International Conference on Green Communications and Networking, GreeNets 2012; Gandia; Spain; 25 October 2012 through 26 October 2012The development of low cost technology based on IEEE 802.11 standard permits to build telecommunication networks at low cost, allowing providing Internet access in rural areas in developing countries. The lack of access to the electrical grid is a problem when the network is being developed in rural areas, so that wireless access points should operate using solar panels and batteries. Many cases can be found where the energy consumption becomes a key point in wireless network design. In this paper we present a comparative study of the energy consumption of several wireless network access points. We will compare the energy consumption of different brands and models, for several operation scenarios and operating modes. Obtained results allow us to achieve the objective of this article, that is, promote the development of wireless communication networks energetically efficient.Andrade Morelli, S.; Ruiz Sanchez, E.; Granell Romero, E.; Lloret, J. (2013). Energy Consumption of Wireless Network Access Points. Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering, LNICST. 113:81-91. doi:10.1007/978-3-642-37977-2_8S8191113Khoa Nguyen, K., Jaumard, B.: Routing Engine Architecture for Next Generation Routers: Evolutional Trends. Network Protocols and Algorithms 1(1), 62–85 (2009)IEEE Std 802.11: IEEE Standard for Information technology -Telecommunications and information exchange between systems -Local and metropolitan area networks - Specific requirements – Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications. Institute of Electrical and Electronics Engineers, New York, USA, pp.1–1184 (2007)Lloret, J., Garcia, M., Bri, D., Sendra, S.: A Wireless Sensor Network Deployment for Rural and Forest Fire Detection and Verification. Sensors 9(11), 8722–8747 (2009)Tapia, A., Maitland, C., Stone, M.: Making IT work for Municipalities: Building municipal wireless networks. Government Information Quarterly 23(3), 359–380 (2006)van Drunen, R., Koolhaas, J., Schuurmans, H., Vijn, M.: Building a Wireless Community Network in the Netherland. In: USENIX 2003 / Freenix Annual Technical Conference Proceedings, San Antonio, Texas, USA, June 9-14, pp. 219–230 (2003)Powell, A., Shade, L.R.: Going Wi-Fi in Canada: Municipal and Community Initiatives. Canadian Research Alliance for Community Innovation and Networking (2005)Sendra, S., Fernández, P.A., Quilez, M.A., Lloret, J.: Study and Performance of Interior Gateway IP routing Protocols. Network Protocols and Algorithms 2(4), 88–117 (2010)Galperin, H.: Wireless Networks and Rural Development: Opportunities for Latin America. Information Technologies and International Development 2(3), 47–56 (2005)Segal, M.: Improving lifetime of wireless sensor networks. Network Protocols and Algorithms 1(2), 48–60 (2009)Momani, A.A.E., Yassein, M.B., Darwish, O., Manaseer, S., Mardini, W.: Intelligent Paging Backoff Algorithm for IEEE 802.11 MAC Protocol. Network Protocols and Algorithms 4(2), 108–123 (2012)Mohsin, A.H., Bakar, K.A., Adekiigbe, A., Ghafoor, K.Z.: A Survey of Energy-aware Routing protocols in Mobile Ad-hoc Networks: Trends and Challenges. Network Protocols and Algorithms 4(2), 82–107 (2012)Feeney, L.M., Nilsson, M.: Investigating the Energy Consumption of a Wireless Network Interface in an Ad Hoc Networking Environment. In: Proceedings of the Twentieth Annual Joint Conference of the IEEE Computer and Communications Societies, INFOCOM 2001, Anchorage, Alaska, April 22-26, vol. 3, pp. 1548–1557. IEEE (2001)Barbancho, J., León, C., Molina, F.J., Barbancho, A.: Using artificial intelligence in routing schemes for wireless networks. Computer Communications 30(14-15), 2802–2811 (2007)Tao, C., Yang, Y., Honggang, Z., Haesik, K., Horneman, K.: Network energy saving technologies for green wireless access networks. IEEE Wireless Communications 18(5), 30–38 (2011)Sendra, S., Lloret, J., Garcia, M., Toledo, J.F.: Power saving and energy optimization techniques for Wireless Sensor Networks. Journal of Communications 6(6), 439–459 (2011