1,721,155 research outputs found
Bayesian localization in sensor networks: distributed algorithm and fundamental limits
No full textSelf-localization in ad-hoc sensor networks is becoming a crucial issue for several location-aware applications. This technology implies the combination of absolute anchor locations with relative inter-node information exchanged on a peer-to-peer basis. In this paper we investigate a distributed algorithm and fundamental performance bounds for Bayesian cooperative localization in stochastic networks. Nodes are assumed to be randomly deployed within a finite space according to a prior distribution. Bayesian inference is performed through an iterative local message passing procedure based on belief propagation and particle-filtering message representation. The algorithm performance is analyzed for a simplified scenario in which unknown node positions are randomly scattered along a line segment and anchors are fixed. Global Cramer-Rao bounds are derived and compared to the performance of the distributed algorithm
Improving Pre-Post Rake Schemes for DS/CDMA Mobile Communications
No full textA technique known as Pre-Post-Rake has been recently proposed
in the field of mobile communications. It provides a capacity
increase in the downlink by means of alternative solution to the
standard Rake processing and to the Pre-Rake approach. In this
paper we focused our work on the Pre-Post-Rake and presented a
new Pre-Post-Rake scheme that acts as a multi-path channel
equalizer. Compared with conventional methods, it reduces the
effect of interferences and further improves the performance, in
both single user and multi-user environments. The penalizing of
this new method is just little extra computational complexity
which can be compensated by a reasonable capacity gain
Effective PN Code Acquisition in Global Positioning Systems for New Generation Wireless Networks and Services
No full textPerformance of the Smart Antenna Aided Generalized Multicarrier DS-CDMA Downlink using both Time-Domain Spreading and Steered Space-Time Spreading
No full textIn this contribution a generalized MC DS-CDMA system invoking smart antennas for improving the achievable performance in the downlink of the system is studied, which is capable of minimizing the downlink interference inflicted upon co-channel mobiles, while achieving frequency, time and spatial diversity. In the MC DS-CDMA system considered the transmitter employs multiple antenna arrays and each of the antenna arrays consists of several antenna elements. More specifically, the space-time transmitter processing scheme considered is based on the principles of Steered Space-Time Spreading (SSTS). Furthermore, the generalized MC DS-CDMA system employs time and frequency (TF)-domain spreading, where a user-grouping technique is employed for reducing the effects of multiuser interference
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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