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Time filter

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Singapore, Singapore

Mandal M.K.,Ecole Polytechnique de Montreal | Chen Z.N.,Institute for Infocom Research
IEEE Transactions on Antennas and Propagation | Year: 2011

Compact planar loop antennas fed by coplanar striplines (CPS) are presented for dual-band and ultrawideband (UWB) operations. The dual-band antenna consists of two resonant radiating parts, namely a strip loop and a slot loop. Based on the dual-band design, a wideband operation can be achieved. Two prototype antennas operating at the 2.4/5 GHz wireless LAN bands with dimensions of 45× 15×0.813 mm3 and for the lower UWB band (3.1-4.8 GHz) with dimensions of 34×13.5×0.813 mm3 were fabricated on a RO4003 substrate. The measured input reflection loss is lower than 15 dB for the dual-band antenna and 10 dB for the UWB antenna. Both of the antennas show acceptable gain and dipole-like radiation patterns over the operating frequency bands. © 2011 IEEE. Source


Wei Z.,University of Liverpool | Zhu X.,University of Liverpool | Sun S.,Institute for Infocom Research | Huang Y.,University of Liverpool | And 2 more authors.
IEEE Journal on Selected Areas in Communications | Year: 2015

We provide a comprehensive energy efficiency (EE) analysis of the full-duplex (FD) and half-duplex (HD) amplify-and-forward (AF) relay-assisted 60-GHz dual-hop indoor wireless systems, aiming to answer the question of which relaying mode is greener (more energy efficient) and to address the issue of EE optimization. We develop an opportunistic relaying mode selection scheme, where FD relaying with one-stage self-interference cancellation (passive suppression) or two-stage self-interference cancellation (passive suppression + analog cancellation) or HD relaying is opportunistically selected, together with transmission power adaptation, to maximize the EE with given channel gains. A low-complexity joint mode selection and EE optimization algorithm are proposed. We show a counter-intuitive finding that with a relatively loose maximum transmission power constraint, FD relaying with two-stage self-interference cancellation is preferable to both FD relaying with one-stage self-interference cancellation and HD relaying, resulting in a higher optimized EE. A full range of power consumption sources is considered to rationalize our analysis. The effects of imperfect self-interference cancellation at relay, drain efficiency, and static circuit power on EE are investigated. Simulation results verify our theoretical analysis. © 2015 IEEE. Source


Chen K.-C.,National Taiwan University | Chen P.-Y.,University of Aalborg | Prasad N.,University of Aalborg | Liang Y.-C.,Institute for Infocom Research | Sun S.,Institute for Infocom Research
Wireless Communications and Mobile Computing | Year: 2010

Networking cognitive radios and nodes from primary system (PS) results in a heterogeneous coexisting multiradio wireless network, so that significant network throughput gain can be achieved. However, by investigating cognitive radio network (CRN) architecture, the links in CRNs are unlikely to support complete security check due to link dynamics, opportunistic availability, and uni-directional in available time window. We therefore introduce trusted cognitive radio networking (TCRN) concept to facilitate network functions such as association in dynamic spectrum access and routing. First of all, we explore the mathematical framework for trust in CRNs.We then show successful association of node to CRN based on the mathematical structure of trust from statistical decision theory. Furthermore, we modify the machine-learning algorithm to update the trust measure for each node, and develop rules of thumbs to facilitate TCRN with learning capability, based on numerical simulations. Trusted CRN can greatly alleviate heterogeneous challenge for CRN operation. Copyright © 2009 John Wiley & Sons, Ltd. Source


Mandal M.K.,Institute for Infocom Research | Chen Z.N.,Institute for Infocom Research
Microwave and Optical Technology Letters | Year: 2010

In this article, a coplanar stripline (CPS) coupling configuration is presented for a compact, ultra-wideband (UWB), uniplanar bandpass filter with a notched band. The passband width of the filter is greatly increased by adding two parallel strips with a coupled-CPS section. Furthermore, spur line is used to create a notched band in the UWB passband to reject the undesired wireless local-area network radio signals in 5 GHz bands. The notched band can be tuned by varying the spur line length. One prototype bandpass filter is fabricated with overall size of 17 × 7.2 mm2 on a 0.813-mm thick substrate with dielectric constant of er = 3.38. Copyright © 2010 Wiley Periodicals, Inc. Source

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