This paper presents major results and comparisons of radio spectrum utilization measurements that have been carried out in three different locations in Europe, namely in the suburb of the city of Brno in the Czech Republic and in the suburb and the city of Paris in France during years 2008 and 2009 respectively. The analyzed radio bandwidth extends from 400 MHz to 3 GHz. The measurement method is based on the energy detection principle. Utilization performance and behaviors of major wireless communication systems and primary wireless system within different regions and different environments are investigated here. Our analyses pick out correlations between spectrum utilization within different regions and summarize common observations and physical aspects that will have to be considered in the future radio spectrum management to assure efficient spectrum utilization.

This letter presents envelope elimination and restoration (EER) architecture specifications in the case of orthogonal frequency division multiplex C band transmission. A key point is the recombination of envelope and phase information by supply modulation of the power amplifier (PA). Imperfections, such as time mismatch and phase noise can reduce the performances of the transmission. Compression and conversion effects when supply modulating the PA are introduced in this letter with the simulation of a class power amplifier. This amplifier was designed under HP-ADS using a nonlinear Mesfet model. Results are reported in terms of error vector measurement and spectrum for two different numbers of sub-carriers 32 and 128 in 16-QAM and 64-QAM cases.Index Terms-Class , envelope elimination and restoration (EER), orthogonal frequency division multiplex (OFDM).

Telemedicine is producing a great impact in the monitoring of patients located in remote nonclinical environments such as homes, elder communities, gymnasiums, schools, remote military bases, ships, and the like. A number of applications, ranging from data collection, to chronic patient surveillance, and even to the control of therapeutic procedures, are being implemented in many parts of the world. As part of this growing trend, this paper discusses the problems in electrocardiogram (ECG) real-time data acquisition, transmission, and visualization over the Internet. ECG signals are transmitted in real time from a patient in a remote nonclinical environment to the specialist in a hospital or clinic using the current capabilities and availability of the Internet. A prototype system is composed of a portable data acquisition and preprocessing module connected to the computer in the remote site via its RS-232 port, a Java-based client-server platform, and software modules to handle communication protocols between data acquisition module and the patient's personal computer, and to handle client-server communication. The purpose of the system is the provision of extended monitoring for patients under drug therapy after infarction, data collection in some particular cases, remote consultation, and low-cost ECG monitoring for the elderly.

Abstract-This paper presents a transmitter architecture which is less sensitive to power amplifier AM/AM and AM/PM conversions. Indeed, most radio communication standards employ nonconstant envelope modulation such as in the 802.11 series. Owing to power amplifiers' nonlinearities, distortions on the modulations degrade the overall transmitter performance. As a consequence, linearization methods, such as envelope elimination and restoration, have to be employed. The architecture relies on the transformation of a nonconstant envelope modulation to a constant or switched one. This signal coding enables the efficient amplification of the signal without undergoing power amplifier distortions. The envelope variation is restored by bandpass filtering just after the power amplifier.

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This paper deals with spectrum utilization measurements in the frequency band from 100 MHz up to 3 GHz. The measurement is based on the energy detection principle using wideband logarithmically periodic antenna. The results point out the fact, that the frequency spectrum is not utilized in an optimal manner and that there do exist less or more utilized licensed frequency bands that could be possibly used by cognitive radios in an opportunistic way. Cognitive radio concept for better spectrum utilization is introduced here along with an overall approach regarding spectrum utilization in the next generation wireless networks.Index Terms -Cognitive radio, radio spectrum management, spectrum sensing, spectrum utilization.

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