We consider a non-orthogonal multiple access (NOMA) cooperative SPECTRUM SHARING network, where a multi-antenna secondary transmitter assists transmission of a primary transmitter-receiver pair, and at the same time transmits to a secondary receiver. The secondary transmitter is assumed to be full-duplex and energy-constrained. Therefore, secondary transmitter replenishes its battery storage via energy harvesting from an energy access point located in its vicinity. In order to cancel the self-interference at the secondary transmitter, two zero-forcing (ZF)-based beamforming schemes and one maximum ratio combining/maximum ratio transmission (MRC/MRT) scheme are designed. Then, corresponding outage probability analysis of the primary and secondary networks with proposed beamforming schemes are derived. Outage probability results are used to study the delay-constrained throughput of the system. Our results suggest that by utilizing ZF-based beamforming schemes, significant performance improvement can be achieved compared to the half-duplex counterpart. Moreover, our results indicate that proposed ZF-based schemes achieves a zero-diversity order.

This paper presents performance evaluations for two SPECTRUM-SHARING cognitive-radio systems employing cooperative amplify-and-forward relaying in which the best relay is selected for the transmission. In these systems, a secondary user (SU, unlicensed user) shares the SPECTRUM of a primary user (PU, licensed user), in such a way that the interference to the PU is always kept below a predefined threshold. To this end, a power control for the SU is used. In these systems, the SU employs an amplify-and-forward relaying with several relays, where the best relay who has the best channel condition is selected for the transmission. The considered systems are different in the employed relay selection schemes, such that: 1) In the first system, partial relay selection is employed, in which the partial channel state information (CSI) is used to select the best relay. 2) In the second system opportunistic relay selection is employed, in which the full CSI is used to select the best relay. To analyze the system performances, at first the cumulative distribution function (CDF) of the received signal-to-noise-ratio (SNR) for each considered system is derived. Then, using the obtained CDF expressions, closed-form expressions are obtained for three performance metrics: outage probability, the average bit-error-rate (BER), and the average channel capacity. Finally, using the numerical results obtained from the mathematical formulas derived in this paper, we evaluate and compare the systems performances in different cases under different conditions. In addition, to verify the accuracy of the performed analysis, Monte-Carlo simulation results are also provided.

Legal institutions namely, ownership are arisen out of human needs and social developments. This article deals with one new kind of ownership (Time SHARING). To establish this matter, it has been explained that ownership can be stipulated to "Time", as well as to "Decimal fraction" which results in "Joint ownership".The first chapter is allocated to general subjects about ownership in order to be known that this sort of ownership is in harmony with permanent ownership as far as definition, elements and attributes are concerned. The only difference is in eternity (just in one of three meanings of eternity). The second chapter deals with pros and cons of this institution.Theoretical justification of this sort of ownership and some samples of it have been presented in the third and forth chapters.

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Nowadays, the SPECTRUM is becoming more and more scarce because of not only the demand increase for wireless services and applications but also inflexible and rigid SPECTRUM allocation policies. A promising solution to overcome this challenge is to exploit SPECTRUM holes for secondary users in cognitive radio. Taking advantage of cognitive radio and dynamic SPECTRUM access improves the efficiency of SPECTRUM utilization as it allows secondary users to exploit the available frequency bandwidth. Inan opportunistic SPECTRUM access scenario, the secondary users can only utilize the frequency bandwidth when the primary user is inactive. In this paper, we assume that secondary users exploit the available frequency bandwidth using opportunistic SPECTRUM access approach. As a result, one may model the available bandwidth to the secondary users as a random process taking value of 0 or 1. In this paper, we investigate the effects of Rayleigh fading environment on the capacity of AWGN point-to-point channel. Afterwards, we also go beyond point to point channels and analyze Multiple Access Channels. More precisely, we derive the closed form expression of ergodic capacity region of Multiple Access fading Channel with two independent sources. To the best of our knowledge, no prior work has investigated the ergodic capacity region of Multiple Access Channel under Rayleigh fading with the aforementioned approach. Numerical analysis are conducted to validate our theoretical results. Interestingly, numerical results indicate that, against the common sense, capacity of Rayleigh fading environment channels are higher than deterministic ones in Gaussian point-to-point channels.