The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
A key technology in cognitive radio (CR) is spectrum sensing that senses the spectrum and reports the available vacant channels. However, due to some effects such as fading or shadowing, an individual sensor may not be able to reliably detect the existence of a primary user (PU). Cooperative spectrum sensing that is proposed to solve such problem, uses a distributed detection system to overcome the...
In this paper, distributed power allocation schemes are studied for amplify-and-forward (AF) cooperative relay networks, where only partial channel state information (CSI) is available at the source and relays. Aiming at minimizing the total transmit power while providing a target outage probability, a scheme is first investigated in which the source decides transmit power and a relay-forwarding threshold,...
The characteristics of ultra-wideband (UWB) channels in vehicular environments are explored. A set of propagation measurements were conducted on roadways and in underground parking garages and the resulting propagation data consists of approximately 1,200 multipath profiles. The channel impulse responses are estimated from the measured data using generalized maximum likelihood. The statistics of channel...
A cooperative approach to the sensing task of wireless cognitive radios (CRs) is introduced based on a basis expansion model of the power spectral density (PSD) in space and frequency. Joint estimation of the model parameters enables identification of the (un)used frequency bands at arbitrary locations and thus facilitates spatial frequency reuse. The novel scheme capitalizes on the sparsity introduced...
This work presents new eigenvalue bounds, necessary conditions and existence results for approximately universal linear (lattice) codes that can be drawn from lattices of reduced dimension, and can thus incur reduced decoding complexity. Currently for the n times nr MIMO channel, all known n times T approximately universal codes, except for the Alamouti code for n = 2,nr = 1, draw from lattices of...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.