This paper explores a variety of different CMOS varactor structures for RF and MMICs. A typical 0.18 μm CMOS foundry process was used as the study platform. The varactors’ capacitance-voltage characteristics and cutoff frequencies have been examined up to 55 GHz. The primary aim of this work is to design varactors that can improve nonlinear-transmission-line (NLTL) pulsecompression circuits. Th...

Recently, Cognitive radio and Smart Grid are two areas which have received considerable research impetus. Cognitive radios are fully programmable wireless devices that can sense their environment, and dynamically adapt their transmission waveform, channel access method, spectrum use, and networking protocols. It is widely anticipated that cognitive radio technology will become a general-purpose...

The need for reliable data communication performed in critical conditions and the respect of real-time constraints is an open issue in radio-military networks, where fixed and nomadic terminals communicate by means of tactical radio infrastructures. In this perspective the need for real-time constraints plays a fundamental role when the interested applications are remote control, radar traces a...

A terahertz-wave communication system directly connected to an optical fiber network is promising for application to future mobile backhaul and fronthaul links. The possible broad bandwidth in the terahertz band is useful for high-speed signal transmission as well as radio-space encapsulation to the high-frequency carrier. In both cases, the low-latency feature becomes important to enhance the ...

The recent surge in the use of personal mobile communication devices have opened up new avenues for communication. While most existing applications designed to exploit this potential are infrastructure based, there is a growing trend to leverage physical proximity between end-users to enable direct peer-to-peer communication. However, the success of these applications relies on the ability to e...

The prosodic features of a message are key factors in the transmission of information by radio. Some authors have demonstrated that perception and proper comprehension of radio news depend largely on the intonation, stress and speech rate used by the broadcaster. The aim of this study, therefore, is to determine the degrees of perception and recognition of information broadcast by radio when th...

Multicast transmission is one of the major goals for Universal Mobile Telecommunication System (UMTS) that motivated the 3 Generation Partnership Project (3GPP) to launch the Multimedia Broadcast/Multicast Service (MBMS) framework. MBMS constitutes a significant step towards the so-called Mobile Broadband, since it allows the efficient utilization of network and radio resources. One of most imp...

This article proposes a hybrid algorithm for spectrum allocation in cognitive radio networks based on the algorithms Analytical Hierarchical Process (AHP) and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) to improve the performance of the spectrum mobility of secondary users in cognitive radio networks. To calculate the level of performance of the proposed algorithm...

For the simulation and design of smart antenna transmission principles in mobile radio, precise knowledge of the time-variant directional multipath structure in various radio environments is required. In this paper a new broadband multiple-input-multiple-output (MIMO) vector radio channel sounder is described which uses multiple antennas at the transmitter as well as at the receiver position. T...

Cognitive radio is an emerging technology that enables the flexible development, construction, production, shipping, and deployment of highly adaptive radios that are built upon software defined radio technology. This contribution starts with a brief section that underlines the paramount importance of the mobile radio communications channel. Then, spectrum issues are discussed to emphasize the ...