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Wireless Devices (wireless + device)
Selected AbstractsCompact shorted patch antenna mounted above the system ground plane of a wireless device for WLAN operationMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2006Kin-Lu Wong Abstract A novel compact shorted patch antenna suitable to be mounted above the system ground plane of a wireless communication device is presented. With the proposed design, the antenna does not directly occupy the system ground plane, thus leaving the board space of the system ground plane or circuit board almost intact for employing the antenna. In this case, the associated components of the wireless device can still be placed on the system ground plane or circuit board under the antenna, with the performances of the antenna almost unaffected. An example of the proposed design applied to a wireless device for WLAN operation in the 2.4-GHz band (2400,2484 MHz) is demonstrated. The experimental results are presented and discussed. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 474,476, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21382 [source] Active measurements of antenna diversity performances using a specific test-bed, in several environmentsINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 3 2010Moctar Mouhamadou Abstract The diversity performances of the wireless devices operating in a multipath propagation environment are usually presented in terms of correlation coefficient, diversity gain and effective diversity gain. These parameters can be measured in reverberation chamber. This paper presents some active measurements of antenna diversity performances on a small wireless terminal in several realistic environments. The measurements were performed in the WiMax band, i.e. at 3.5 GHz, in a reverberation chamber where the channel is statistically uniform, in a real indoor propagation channel, and in an outdoor-to-indoor environment. The diversity performances are evaluated by using a specific test-bed constituted by an arbitrary signal generator and two radio-frequency digitizers. The effectiveness of diversity is presented in terms of effective diversity gain, signal to noise ratio, bit error rate and frame error rate. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010. [source] A small wideband planar monopole antenna for mobile wireless devicesMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2006Jihak Jung Abstract A small wideband planar monopole antenna for mobile wireless devices is designed and implemented. The proposed antenna satisfies the ,10-dB return-loss requirement from 1.62 to 10.9 GHz. The antenna can easily cover the DCS1800/1900, IMT-2000, WiBro, WLAN, DMB, and UWB bands at the same time. The experimental and numerical results of the designed wideband antenna are presented and analyzed. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 736,740, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21460 [source] Cost minimization in wireless networks with a bounded and unbounded number of interfacesNETWORKS: AN INTERNATIONAL JOURNAL, Issue 3 2009Ralf Klasing Given a graph G = (V,E) with |V| = n and |E| = m, which models a set of wireless devices (nodes V) connected by multiple radio interfaces (edges E), the aim is to switch on the minimum cost set of interfaces at the nodes to satisfy all the connections. A connection is satisfied when the endpoints of the corresponding edge share at least one active interface. Every node holds a subset of all the possible k interfaces. Depending on whether k is a priori bounded or not, the problem is called Cost Minimization in Multi-Interface Networks or Cost Minimization in Unbounded Multi-Interface Networks, respectively. We distinguish two main variations for both problems by treating the cost of maintaining an active interface as uniform (i.e., the same for all interfaces), or nonuniform. For bounded k, we show that the problem is APX-hard while we obtain an approximation factor of min for the uniform caseand a (k , 1)-approximation for the nonuniform case. For unbounded k, i.e., k is not set a priori but depends on the given instance, we prove that the problem is not approximable within O(log k) while the same approximation factor of the k -bounded case holds in the uniform case, and a min -approximation factor holds for the nonuniform case. Next, we also provide hardness and approximation results for several classes of networks: with bounded degree, trees, planar, and complete graphs. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009 [source] Electromagnetic safety of children using wireless phones: A literature reviewBIOELECTROMAGNETICS, Issue S7 2005Luc Martens Abstract In this article, several issues related to the safety of electromagnetic field exposure of children when using wireless devices such as mobile phones are described. The information available in the literature is reviewed and open areas that need to be subject of future research are identified. A lack of proof that dielectric properties change with age and an inconsistency in absorption studies in children is reported. The number of biological studies relevant to children is limited. Only some of the cognitive studies specifically target children and these show no significant effect of exposure. There is also a need to investigate the impact of electromagnetic fields on the developmental process of children. All this makes a definitive answer to the question if children are more sensitive to electromagnetic fields than adults impossible. More consistent research will be needed. This study is part of the European COST281 project "Potential Health Implications from Mobile Communication Systems." Bioelectromagnetics Supplement 7:S133,S137, 2005. © 2005 Wiley-Liss, Inc. [source] | ||||||||||