For fully autonomous implantable or body-worn devices running on harvested energy, the peak and average power dissipation of the radio transmitter must be minimized. We propose a highly integrated 90μW 400MHz MICS band transmitter with an output power of 20μW leading to a 22% global efficiency — the highest reported to date for such systems. We introduce a new transmitter architecture based on ...

This paper describes the development of a WLAN propagation model, using Spectral Analyzer measurements. The signal is generated by two Access Points (APs) on the base floor at the administrative Communication School of ESPOL building. In general, users do not have a Q&S reference about a wireless network; however, this depends on the level signal as a function of frequency, distance and other p...

With the advancement of battery technology, energy harvesting communication systems attracted great research attention in recent years. However, energy harvesting communication systems with multiple transmitters and multiple receivers have not been considered yet. In this paper, the problem of broadcasting in a communication system with multiple energy harvesting transmitters and multiple recei...

With the advent of cognitive radio technology, new paradigms for spectrum access can achieve nearoptimal spectrum utilisation by letting each user sense and utilise available spectrum opportunistically while regulating the interference it imposes on other users through interference constraints. However, the most common forms of binary and transmitter-centric constraints are often inef cient sin...

We investigate the secure degrees of freedom (SDoF) of a two-transmitter Gaussian multiple access channel with multiple antennas at the transmitters, a legitimate receiver and an unknown number of eavesdroppers each with a number of antennas less than or equal to a known value NE . The channel matrices between the legitimate transmitters and the receiver are available everywhere, while the legi...

In this article we review FCC secondary markets initiatives and how smart wireless devices could be used to increase spectral efficiency. We survey the current proposals for cognitive radio deployment, and present a new, potentially more spectrally efficient model for a wireless channel employing cognitive radios; the cognitive radio channel. This channel models the simplest scenario in which a...

Wireless connections are established by the use of a transmitter which is sending radio waves at a specific frequencies to a receiver. Nowadays, due to the variety of different services, only a restricted part of the radio spectrum is available. The set of available frequencies for a provider of a wireless communication service is limited even further by concurrent providers and local frequency...

*1 “Xi” (Crossy): “Xi” (read “Crossy”) and its logo are trademarks of NTT DOCOMO. *2 OFDMA: A radio access scheme that uses Orthogonal Frequency Division Multiplexing (OFDM). OFDM uses multiple low data rate multi-carrier signals for the parallel transmission of wideband data with a high data rate, thereby implementing high-quality transmission that is highly robust to multipath (see *3) interf...

High system capacities can be achieved by controlling the transmitter power in multiuser radio systems. Power control with no constraint on the maximum power level has been studied extensively in earlier work([1]-[18]). Transmitter power is at a premium in radio systems such as cellular systems and PCS. There is a limit on the maximum transmitter power especially at the terminals (eg. mobile un...

This paper is concerned with spectrum sharing cognitive radio networks, where a secondary user (SU) or cognitive radio link communicates simultaneously over the same frequency band with an existing primary user (PU) link. It is assumed that the SU transmitter has the perfect channel state information (CSI) on the fading channels from SU transmitter to both PU and SU receivers (as usually assume...