| 1. |
- Lam, Thanh Tu, et al.
(författare)
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Performance Evaluation of Incremental Relaying in Underlay Cognitive Radio Networks with Imperfect CSI
- 2021
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Ingår i: IEEE ICCE 2020: 2020 IEEE EIGHTH INTERNATIONAL CONFERENCE ON COMMUNICATIONS AND ELECTRONICS (ICCE). - : IEEE. - 9781728154718 ; , s. 472-477
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Konferensbidrag (refereegranskat)abstract
- The performance of both primary and secondary networks in underlay cognitive radio networks (CRNs) with the help of incremental amplify and forward (IAF) relaying under imperfect channel state information (CSI) are investigated. Particularly, the interference probability at primary networks denoted by IP as well as the outage probability at secondary networks denoted by OP, are computed in the closed-form expressions. Our findings show that the impact of the imperfect CSI on the performance of IP is non-negligible. To tackle the high value of IP, reducing the transmit power at the secondary transmitters is a proper solution, it, however, will also increase the OP at the secondary networks. Thus, a simple power control coefficient is proposed to compromise the performance between two networks. Finally, Monte-Carlo simulations are provided to verify the accuracy of the proposed mathematical frameworks.
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| 2. |
- Hoa Nguyen, Tien, et al.
(författare)
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Performance Analysis and Optimization of the Coverage Probability in Dual Hop LoRa Networks With Different Fading Channels
- 2020
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Ingår i: IEEE Access. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2169-3536. ; 8, s. 107087-107102
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the performance evaluation and the optimization of dual-hop LoRa network are investigated. In particular, the coverage probability (Pcov) of edge end-devices (EDs) is computed in closed-form expressions under various fading channels, i.e., Nakagami-m and Rayleigh fading. The Pcov under Nakagami-m fading is computed in the approximated closed-form expressions; the Pcov under Rayleigh fading, on the other hand, is calculated in the exact closed-form expressions. In addition, we also investigate the impact of different kinds of interference on the performance of the Pcov, i.e., intra-SF interference, inter-SF interference (or capture effect) and both intra- and inter-SF interference. Our findings show that the impact of imperfect orthogonality is not non-negligible, along with the intra-SF interference. Moreover, based on the proposed mathematical framework, we formulate an optimization problem, which finds the optimal location of the relay to maximize the coverage probability. Since it is a mixed integer program with a non-convex objective function, we decompose the original problem with discrete optimization variables into sub-problems with a convex feasible set. After that, each sub-problem is effectively solved by utilizing the gradient descent approach. Monte Carlo simulations are supplied to verify the correctness of our mathematical framework. In addition, the results manifest that our proposed optimization algorithm converges rapidly, and the coverage probability is significantly improved when the location of relay is optimized.
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| 3. |
- Song, Jian, et al.
(författare)
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Bounded Path-Loss Model for UAV-to-UAV Communications
- 2021
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Ingår i: ICWMC 2021 : The Seventeenth International Conference on Wireless and Mobile Communications - The Seventeenth International Conference on Wireless and Mobile Communications. - 9781612088785
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Konferensbidrag (refereegranskat)abstract
- In this paper, we focus on ultra-dense network modelingwhere both the Base Stations (BSs) and Mobile Terminals(MTs) are UAVs. In this case, two communication nodes canbe very close to each other. However, existing cellular networkanalyses typically use the standard unbounded path loss modelwhere received power decays like r^beta over a distance r. Thisstandard model is a good approximation for the path-loss inwireless communications over large values of r but is not validfor small values of r due to the singularity at 0. This model is oftenused along with a random uniform node distribution, even thoughin a group of uniformly distributed nodes some may be arbitrarilyclose to one another, thus, it will lose accuracy and may benot applicable for UAV-to-UAV communications. To tackle thisproblem, by using mathematical tool behind stochastic geometry,we propose tractable analytical frameworks of coverage and ratebased on the novel unbounded path-loss model with a constantdistance factor r_0 for analyzing the UAV-to-UAV communications.
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| 4. |
- Van Chien, Trinh, et al.
(författare)
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Outage Probability Analysis of IRS-Assisted Systems Under Spatially Correlated Channels
- 2021
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Ingår i: IEEE Wireless Communications Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 2162-2337 .- 2162-2345. ; 10:8, s. 1815-1819
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Tidskriftsartikel (refereegranskat)abstract
- This letter investigates the impact of spatial channel correlation on the outage probability of intelligent reflecting surface (IRS)-assisted single-input single-output (SISO) communication systems. In particular, we derive a novel closed-form expression of the outage probability for arbitrary phase shifts and correlation matrices of the indirect channels. To shed light on the impact of the spatial correlation, we further attain the closed-form expressions for two common scenarios met in the literature when the large-scale fading coefficients are expressed by the loss over a propagation distance. Numerical results validate the tightness and effectiveness of the closed-form expressions. Furthermore, the spatial correlation offers significant decreases in the outage probability as the direct channel is blocked.
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