Earticle

We focus on the energy detection based spectrum sensing in a cognitive radio system and provide closed-form expressions to evaluate the detection performances. Moreover, we use multiple antennas at the sensing node to exploit the spatial diversity. Besides, a generalized selection combining (GSC) scheme over independent and identically distributed (IID) and exponential correlated Rayleigh fading channels is used to improve the sensing performance especially in low signal-to-noise regimes.

In a health care context, the use RFID (Radio Frequency Identification) technology can be employed for not only bringing down health care costs but also facilitate automating and streamlining patient identification processes in hospitals and use of mobile devices like PDA, smart phones, for design a health care management systems over wireless sensor network. In this paper, we propose a Hospital RFID-based u-Healthcare Management System architecture that possesses the essential elements of each of the future medical applications are integration with existing medical practices and technology, real-time, long-term, remote monitoring, miniature, wearable sensors to assist patients most especially the elderly and chronic patients.

Spectrum sensing plays an essential role in Cognitive Radio which enables opportunistic access to inefficiency licensed spectrum. Collaborative spectrum sensing can help increasing sensing performance. However, when the number of cognitive users is large, the latency and network traffic for exchanging sensing results become extremely large. Furthermore, in the case of infrastructureless network like cognitive radio ad hoc network, the coordination for the sensing cooperation is really difficult due to the lack of a central controller. In this paper, we introduce a sensing information collection mechanism that enables the sequential combination based on the Dempster Shafer theory of evidence by using the ordered data reliability broadcasting. The proposed methods not only require minimum coordination but also reduce the overhead of control channel and the sensing result collecting time while keeping the same sensing performance in comparison with the conventional cooperative centralized spectrum sensing scheme.

Orthogonal frequency division multiplexing (OFDM) technique is a promising technique to offer high data rate and reliable communications over fading channels. The main implementation disadvantage of OFDM is the possibility of high peak to average power ratio (PAPR). This paper presents a novel technique to reduce the PAPR using turbo coding and selective mapping (SLM). We show that the probability of the PAPR of OFDM signal with 512 subcarriers in a 16-QAM channel can be reduced by 25% in a Turbo selector. The rest of the paper, simulation results are superimposed by using Matlab interface as well.

The filtering characteristics of metal-strip gratings printed on planar dielectric slabs are analyzed numerically by using a rigorous modal transmission-line theory (MTLT). It can serve as a template for computational algorithms that systematically evaluate the effects.