1,721,117 research outputs found
Image-Processing-Based Transceiver Design for Acoustic PPM Underwater Links
No full textUnderwater pulse position modulation (PPM) transmission uses acoustic pulses since they allow communication, remote control of underwater vehicles, and positioning estimation; the last one when more than one detector is present by using only one technology, that is, the same transmission module. On the other hand, PPM pulses are difficult to detect since they carry information on signal delays, assuring that reliable information delivery both in shallow- and deep-sea channels may be considered a timely challenge due to strong multipath and other interference sources/causes giving rise to signal fluctuation and high noise level. This paper proposes a transceiver architecture characterized by a signal analyzer and an adaptive detection based on the channel features. The signal analysis is based on the Wigner–Ville transform (WVT) that converts a 1-D signal into an image. Edge detection procedures performed on the obtained image so as to discover the interference features and understand the main characteristics of multipath with their adverse effects on detection of pulse position information have been taken into account. Based on this, maximal ratio combining (MRC) and equal gain combining (EGC) for RAKE reception and truncated channel equalization have been considered. Numerical results showing the ability of the proposed transceiver to detect pulses in the presence of multipath and interference generated by external acoustic sources have been carried out also by taking into account the estimation error effects and by comparing the actual performance with ideal cases. Finally, field tests corroborate the reliability of the proposed approach
MIMO self-interference mitigation effects on PLC relay networks
No full textPower Line Communications (PLCs) enable new and highly convenient networking functions in the framework of Smart-Grids and use an already built-in network. A Multiple Input Multiple Output (MIMO) architecture can strongly improve the PLC performances and links' reliability. In this contribution the effect of self-interference generated by relay nodes has been considered and the MIMO potentials for spatial multiplexing and interference suppression have been taken into account. The importance of channel knowledge has been also considered from a numerical result point of view in order to give some instruments for network planning. © 2011 IEEE
Acoustic PPM image processing for underwater communications
No full textPulse position modulated (PPM) acoustic pulses are difficult to detect since they carry information on delays so, assuring reliable information delivery mainly in shallow sea channels because of strong multipath and other interference sources/causes, large signal fluctuation and high noise level may be considered a timely challenge. This paper proposes a signal analysis based on the Wigner-Ville transform and subsequent image processing so to understand the main characteristics of multipath and interference and their adverse effects on detection of pulse position information. By basing on this approach performance of Maximal Ratio Combining (MRC) and Equal Gain Combining (EGC) have been taken into account. © 2011 IEEE
MIMO Self-Interference Mitigation Effects on Power Line Relay Networks
No full textPower Line Communications (PLCs) enable new and highly convenient networking functions in the framework of Smart-Grids and use an already built-in network. A Multiple Input Multiple Output (MIMO) architecture can strongly improve the PLC performances and links' reliability. In this contribution the effect of self-interference generated by relay nodes has been considered and the MIMO potentials for spatial multiplexing and interference suppression have been taken into account. The importance of channel knowledge has been also considered from a numerical result point of view in order to give some instruments for network planning
An Opportunistic Access Scheme Through Distributed Interference Control for MIMO Cognitive Nodes
No full textA critical issue of a Cognitive Radio Network is the interference generated by secondary users simultaneously accessing and transmitting over the primary user spectrum band. In this paper, we introduce and study a distributed and opportunistic access scheme for MIMO ad-hoc cognitive radio networks identified as OPTIM-COG (OPporTunistic Interference control for Mimo COGnitive radio). OPTIM-COG is based on simple power stimuli issued by PU transmitters. These stimuli are basic control messages exchanged, at a known power, by both primary transmitter and primary intended receiver for their internal power control. A periodic repetition of this power stimulus and the power control generated in the primary network are used by secondary nodes to get their transmission opportunities. These opportunities are determined with a twofold goal: on the one hand the secondary node will transmit to its secondary receiver only if the quality of the already established primary connection does not decrease below a minimum level, on the other hand the resulting opportunistic access exploits the MIMO performance improvements. We describe the fully distributed version of this access scheme and we theoretically demonstrate, via a game theoretical formulation, that the resulting power allocation is the unique Nash Equilibrium. Performance results present secondary user access maps in the 2D plan, where both MIMO benefits as well as the presence of multiple active secondary links can be represented. Both the cases of a perfect interference measurement and imperfect channel estimation are evaluated
Power-allocation Policy and optimization design of Multiple-Antenna systems with imperfect channel estimation
No full textA Water-Filling based approach for power allocation for Multiple-Antenna Rayleigh Flat Fading systems with Partially Coherent Detection
No full textA New Family of Space-Time Codes for Multi-Antenna Systems with Imperfect Channel Estimation
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