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.
The technology of Direct Sequence Code Division Multiple Access (DS-CDMA) has been chosen for mobile communication systems because of numerous advantages. A major advantage is that it can provide a better capacity compared to the other possible technologies of multiple access. In spread spectrum system the signal bandwidth is increased to a value much larger than is needed to transmit the underlying...
The main objective of this paper is to describe and simulate the application of an interference cancelling technique named Amplitude Domain Processing (ADP) in navigation. ADP is the simplified algorithm of locally optimum detection theory. According to statistical theory, ADP is a non-linear and digital technology and it can eliminate interferences according to the statistical characteristics of...
In this paper we propose a novel switched interleaving algorithm based on limited feedback for downlink DS-CDMA systems. The proposed switched chip-interleaving DS-CDMA scheme requires the cooperation among the transmitter, the receiver and a feedback channel sending the index of the interleaver to be used. The transmit chip-inter leaver is chosen by the receiver from a codebook of interleaving matrices...
We consider here the problem of multi-user detection for randomly spread direct-sequence (DS) coded-division multiple access (CDMA) over flat fading channels. The analysis is focused on the case of many users, and large spreading sequences such that their ratio, which is the system load, is kept fixed. Spectral efficiency of practical linear detectors such as match-filter and decorrelator employing...
Multicarrier code-division multiple access (MCCDMA) system with adaptive frequency hopping (AFH) has attracted attention of researchers due to its excellent spectral efficiency. A suboptimal water-filling (WF) channel allocation algorithm was previously proposed for the reverse link of this system. To overcome the limitations of the WF algorithm in the presence of fading-induced near-far problem,...
Cognitive radio is proposed as an approach to solve the conflict between the spectrum congestion and under-utilization. Energy detector is the detector most widely used in cognitive radio system due to its generality and low complexity. In this paper, the performance of energy detector under noise uncertainty is studied. The discrete form and continuous form of the noise uncertainty model are proposed...
Spectrum sensing is a core problem in cognitive radio. Detecting the presence/absence of very weak primary users with a single antenna can be very difficult. Environmental uncertainties result in SNR walls that detectors cannot overcome. Multiple-antenna approaches show some potential gains, but we show here that single-user multiple-antenna detection still must suffer from an SNR wall. The reason...
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.