In underlay cognitive radio networks, unlicensed secondary users are allowed to share the spectrum with licensed primary users when the interference induced on the primary transmission is limited. In this paper, we pr...
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ISBN:
(纸本)9781424492688
In underlay cognitive radio networks, unlicensed secondary users are allowed to share the spectrum with licensed primary users when the interference induced on the primary transmission is limited. In this paper, we propose a new cooperative transmission scheme for cognitive radio networks where a relay node is able to help both the primary and secondary transmissions. We derive exact closed-form and upper bound expressions of the conditional primary and secondary outage probabilities over Rayleigh fading channels. Furthermore, we proposed a simple power allocation algorithm. Finally, using numerical evaluation and simulation results we show the potential of our cooperative transmission scheme in improving the secondary outage probability without harming the primary one.
This paper presents a new structure of multicopter with its propellers installed in three different *** aim is to achieve complete independent control of position and attitude of the *** can allow us to control the po...
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ISBN:
(纸本)9781538629185
This paper presents a new structure of multicopter with its propellers installed in three different *** aim is to achieve complete independent control of position and attitude of the *** can allow us to control the position with its desired attitude controlled *** such,this new multicopter can hover at any fixed point with its attitude changed *** can not be achieved for the existing *** key feature of this new design is that it provides the practical engineering area with a revelation,i.e.,it is actually not necessary to install robots on the aircraft to accomplish the planned aerial mission because this new multicopter is essentially a six degree-of-freedom aerial *** this novel design,the dynamic model is further established by using the Newton-Euler *** the basis of this,the work of controller design is also carried *** motion feature which the general multicopter can not be achieved is finally verified by numerical simulation.
This work develops a novel framework to analyse the outage probability of narrowband signal transmissions between arbitrary shaped spatial regions. Since the sampling of the spatial regions populated with antennas is ...
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ISBN:
(纸本)9781509009411
This work develops a novel framework to analyse the outage probability of narrowband signal transmissions between arbitrary shaped spatial regions. Since the sampling of the spatial regions populated with antennas is a form of mode excitation, we consider communication between the regions in terms of orthonormal basis functions encoded in wave modes to describe the outgoing/incoming signals in the transmit/receive region. Based on this framework, we first show that analogous to MIMO system, the mutual information (MI) over Rayleigh fading channel for narrowband communication between spatial regions is equivalent to a Gaussian random variable. We then derive an accurate closed-from expression of the outage probability using the definition of MI. In addition, we propose a descending transmit power allocation algorithm. Simulation results indicate that the proposed algorithm outperforms the conventional equal powerallocation scheme even at low SNR (signal to noise ratio) regime.
This paper studies secure layered video transmission in a multiuser multiple-input single-output (MISO) beamforming downlink conununication system. The power allocation algorithm design is formulated as a non-convex o...
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ISBN:
(纸本)9781479930838
This paper studies secure layered video transmission in a multiuser multiple-input single-output (MISO) beamforming downlink conununication system. The power allocation algorithm design is formulated as a non-convex optimization problem for minimizing the total transmit power while guaranteeing a minimum received signal-to-interference-plus-noise ratio (SINR) at the desired receiver. In particular, the proposed problem formulation takes into account the self-protecting architecture of layered transmission and artificial noise generation to prevent potential information eavesdropping. A semi-definite programming (SDP) relaxation based power allocation algorithm is proposed to obtain an upper bound solution. A sufficient condition for the global optimal solution is examined to reveal the tightness of the upper bound solution. Subsequently, two subopthnal powerallocation schemes with low computational complexity are proposed for enabling secure layered video transmission. Simulation results demonstrate significant transmit power savings achieved by the proposed algorithms and layered transmission compared to the baseline schemes.
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