Vesna Blagojevic

Ergodic Capacity for TAS/MRC Spectrum Sharing Cognitive Radio

Spectrum sharing cognitive radio with transmit antenna selection and maximal ratio combining is analyzed, under the peak interference constraint at the primary user receiver. The ergodic capacity of the secondary link with an arbitrary number of transmit and receive antennas is derived, for the case of Rayleigh fading and transmit power constraint. For the case of unlimited transmit power, the closed-form expression for the capacity is derived. The correctness of analytical results is verified by using an independent simulation model.

Ergodic capacity of spectrum sharing cognitive radio with MRC diversity and Nakagami fading

Spectrum sharing cognitive radio with multiple antennas at the primary user receiver and maximal ratio combining applied at the secondary user receiver is analyzed. The closed-form expression is derived for the ergodic capacity of the secondary link with an arbitrary number of receive antennas and Nakagami fading distribution. Analytical expressions are derived for both cases of peak and average interference constraint at the primary user receiver. The correctness of analytical results is verified by using an independent simulation model.

Closed-Form Level Crossing Rates Expressions of Orthogonalized Correlated MIMO Channels

In this paper, the exact closed-form expressions for the level crossing rate (LCR) and the temporal autocorrelation function (ACF) of the signal-to-noise ratio (SNR), at the output of the spatially correlated multiple-input-multiple-output (MIMO) systems with orthogonal space-time block codes (OSTBCs), are derived. The expressions are derived for the case of an arbitrary number of Rayleigh distributed branches and any form of the covariance matrix. The derived identities can be applied to isotropic and nonisotropic scattering environments, and they are validated by Monte Carlo simulations.

Ergodic Capacity of Spectrum Sharing Systems with OSTBC in Nakagami Fading

The spectrum sharing system employing orthogonal space-time block codes (OSTBCs) with both interference and transmit power constraints is analyzed in Nakagami fading environment, for an arbitrary number of transmit and receive antennas of the secondary user (SU). The closed-form expression for the probability density function of the signal-to-noise ratio at the SU receiver is derived. The ergodic capacity expression is derived in the exact closed-form under both interference and transmit power constraints. The analytical results are verified by using an independent simulation method.

Second-order statistics of a maximum ratio combiner with unbalanced and unequally distributed nakagami branches

In this study, exact closed-form expressions for the second-order statistics of the signal-to-noise ratio at a maximum ratio combiner (MRC) output for a Nakagami fading channel are derived. Using the joint characteristic function for the MRC output and its time derivative, the level crossing rate, average fading duration and autocorrelation function expressions are derived for the case of independent but unbalanced diversity branches, with unequal fading parameters and an arbitrary number of diversity branches. The analytical results are validated by simulations.

Performance analysis of energy harvesting DF relay system in generalized-K fading environment

Abstract The performance of decode-and-forward (DF) relaying systems is analyzed for the energy constrained relay and Generalized-K fading environment, assuming that the communication in both links of relaying system is corrupted by effects of multipath fading and shadowing. We analyze the ergodic and outage capacities for two representative cases: in one case energy harvesting and information transmission are arranged based on time-switching relaying protocol, while in the other analyzed case they are arranged based on power-splitting relaying protocol. The novel analytical closed-form results for error performance of DF energy harvesting system are applicable for wide range of modulation formats. The derived closed-form capacity and error rate expressions are valid for both relaying protocols and various scenarios of composite fading environment. Analytical results are corroborated by an independent simulation method. Finally, the impact of the system and channel parameters on the system performance is demonstrated through numerical analysis.

Performance of Spectrum Sharing System in Gamma Shadowed Nakagami-m Fading Environment

Abstract In this paper, the performance of spectrum sharing system in composite Nakagami-m/gamma shadowed channels is analyzed. The environments (of primary and secondary users) corrupted only by noise or interference are considered in details. The novel analytical expressions for outage probability, moment generation function and ergodic capacity are derived in a form of fast-computable Meijer’s G functions, for both mentioned scenarios. Numerical results illustrate the impact of fading and shadowing phenomena on system performance, and appropriate comparison between noise- and interference-limited cases is presented.

Outage Probability and Ergodic Capacity of Spectrum-Sharing Systems with MRC Diversity

Abstract The spectrum sharing system employing maximum ratio combining (MRC) is analyzed in Nakagami fading environment, for the case when the interference from the primary user is present at the input of the secondary user receiver. The closed-form expressions for the probability density function of the signal-to-interference-and-noise ratio, the outage probability and the ergodic capacity of the SU link are derived under both peak interference and maximal transmit power constraints. Asymptotical expressions are provided for the important region where peak interference power constraint dominates and the case when the interference from the primary user’s is dominant compared to the noise at the secondary user’s receiver. The obtained expressions are presented for both cases of outdated and mean-value based power allocation and verified by using Monte Carlo simulation method.

Ergodic capacity of multi-antenna spectrum sharing cognitive radio with outdated CSI

The multi-antenna spectrum sharing cognitive radio system in Nakagami-m fading environment is analyzed in this paper. Both cases when secondary user is provided with perfect and outdated channel state information (CSI) of the channel from the secondary users transmitter to the primary users receiver are considered. Ergodic capacity of spectrum sharing system is studied for different transmission techniques using multiple antennas. It has been shown that the selection of optimal technique is complex and it depends on various factors such as the system dimensions, the fading characteristics of the propagation environment and the delay of provided CSI.

Analysis of SIR for spectrum sharing system with OSTBC in Nakagami fading

This paper analyzes spectrum sharing cognitive radio system where orthogonal space time block codes (OSTBCs) are applied at the secondary user (SU) link. The influence of primary users (PU) interference on the performances of the SU are studied in Nakagami fading environment. We derive exact closed-form expressions for probability density function and moments of the SIR (signal-to-interference ratio) of SU. Ergodic capacity is evaluated for different system parameters. The accuracy of the analytical expressions is verified using Monte Carlo simulation method.