Publications
Journals
J. Vega-Sánchez, L. Urquiza-Aguiar, H. Carvajal, N. Orozco, D. Moya, "Fluid Antenna System: Secrecy Outage Probability Analysis", IEEE Transactions on Vehicular Technology, Early Access, DOI: 10.1109/TVT.2024.3376475.
F. Almeida, F. Albuquerque-Parente, N. Orozco, H. Carvajal, J. C. Silveira Santos Filho, "New Findings on the Sum of Squared Fluctuating Two-Ray Random Variables and Applications", IEEE Transactions on Vehicular Technology, vol. 73, no. 5, pp. 7357-7362, May. 2024.
J. F Arellano, C. D. Altamirano, H. Carvajal, N. Orozco, F. Almeida, "On the Performance of MMSE Channel Estimation in Massive MIMO Systems over Spatially Correlated Rician Fading Channels", Wireless Communications and Mobile Computing, vol. 2024, no. 2, Apr. 2024.
H. Carvajal, N. Orozco, F. Almeida, D. Sanchez, and O. Alcaraz, ``Secure Transmission for Uplink SCMA Systems Over κ- μ Fading Channels'', IEEE Transactions on Vehicular Technology, vol. 73, no. 1, Jan. 2024.
V. Farré, J. Vega-Sánchez, H. Carvajal, "5G NR Radio Network Planning at 3.5 GHz and 28 GHz in a Business/Dense Urban Area from the North Zone in Quito City", Engineering Proceedings, vol. 47, no. 1, Dec. 2023.
J.C. Rodriguez, F. Grijalva, M. García, D. Chérrez, B. Acuña Acurio, H. Carvajal, "Wireless Communication Technologies for Smart Grid Distribution Networks", Engineering Proceedings, vol. 47, no. 1, Dec. 2023.
V. Párraga-Villamar, P. Lupera-Morillo, F. Grijalva, H. Carvajal, "Brief Survey: Machine Learning in Handover Cellular Network ", Engineering Proceedings, vol. 47, no. 1, Sep. 2023.
A. Zambrano, D. Pilacuan, M. Salvador, F. Grijalva, N. Orozco, H. Carvajal, “IrisMath: a Blind- friendly Web-based Computer Algebra System”, IEEE Access, vol. 11, pp. 71766 - 71776, 2023.
P. Tilleria, H. Carvajal, N. Orozco, and F. Almeida, ``On the Performance of Decode-and-Forward Equal-Gain-Combining Relay Systems over Weibull Fading Channels'', Sensors, vol. 23, no. 6, Mar. 2023.
A. Arias, L. Huera, B. Rueda, H. Carvajal, N. Orozco, and F. Almeida, ``On the Secrecy Outage Probability of NOMA Systems affected by Imperfect SIC over k-u Fading Channels'', Journal of Communications, vol. 18, no. 3, pp. 147-155, Mar. 2023.
V. Párraga-Villamar, P. Lupera-Morillo, F. Grijalva, H. Carvajal, "Brief Survey: Machine Learning in Handover Cellular Network", Engineering Proceedings, vol. 47, no. 1, 2023.
H. Carvajal, N. Orozco, S. Cacuango, P. Salazar, E. Rosero, and F. Almeida, "A Scheduling Scheme for Improving the Performance and Security of MU-MIMO Systems, Sensors, vol. 22, no. 14, 2022.
F. Almeida, H. Carvajal, and N. Orozco, "Improved Exact Evaluation of Equal-Gain Diversity Receivers in Rayleigh Fading Channels", IEEE Access, vol. 10, pp. 26974 - 26984, 2022.
F. Almeida, H. Carvajal and N. Orozco, "Novel Expressions for Ricean Sum Distributions and Densities", IEEE Communications Letters, vol. 25, no. 11, pp. 3513-3517, 2021.
F. Almeida García, H. Carvajal, G. Fraidenraich, J. C. Silveira Santos Filho, “Square-Law Detection of Exponential Targets in Weibull-Distributed Ground Clutter”, IEEE Geoscience and Remote Sensing Letters, vol. 18, no. 11, pp. 1956-1960, 2021.
N. Orozco, H. Carvajal, F. Almeida, and D. Altamirano, "On the Bit Error Probability and the Spectral Efficiency of Opportunistic Wireless Transmissions in Rician Fading Channels", IEEE Access, vol. 9, pp. 49267 - 49280, 2021.
D. Altamirano, H. Carvajal, and C. de Almeida, "BER of Massive MIMO in time-variant channels using multiplexed, superimposed and hybrid channel estimation techniques", Elsevier AEU - International Journal of Electronics and Communications, vol. 131, paper no. 153594, 2021.
F. Almeida, H. Carvajal, N. Orozco, J. C. Silveira Santos Filho, “Alternative representations for the probability of detection of non-fluctuating targets”, Electronic Letters, vol. 56, no. 21, pp. 1136-1139, 2020.
H. Carvajal, N. Orozco, D. Altamirano, and C. de Almeida, “Performance Analysis of Non-Ideal Sectorized SFR Cellular Systems in Rician Fading Channels with Unbalanced Diversity”, IEEE Access, vol. 8. pp. 133654 - 133672, 2020.
D. Altamirano, J. Minango, H. Carvajal, and C. de Almeida, “BER Evaluation of Linear Detectors in Massive MIMO Systems Under Imperfect Channel Estimation Effects”, IEEE Access, vol. 7. pp. 174482 - 174494, 2019.
H. Carvajal, N. Orozco, P. Chiliguano and C. de Almeida, Enabling Signal Space Diversity for MU-MIMO/OFDMA Cellular Systems That Employ Frequency Diversity, IEEE Access, vol. 7. pp. 111204 – 111221, 2019.
C. Frison, H. Carvajal, C. de Almeida, “Optimum rotation parameters for single and multiuser signal space diversity employing spatial diversity”, AEU - International Journal of Electronics and Communications, vol. 107, pp. 275-281, 2018.
N. Orozco, H. Carvajal, and C. de Almeida, Performance Evaluation of Encoded Opportunistic Transmission Schemes, IEEE Access, vol. 7. pp. 89316 - 89329, 2019.
N. Orozco, H. Carvajal, and C. de Almeida, “An Opportunistic System to Counteract Fading and Gaussian Interference Effects Under Different Modulation Schemes”, IEEE Latin America Transactions, vol. 16, no. 11, pp. 2716 – 2721, 2018.
H. Carvajal, N. Orozco, and C. de Almeida, Signal Space Diversity in Single and Multiuser Scenarios Employing Sphere Decoder Detector, IEEE Communications Letters, DOI: 10.1109/LCOMM.2018.2797276, 2018.
H. Carvajal, N. Orozco, and C. de Almeida, On the cellular spectral efficiency of MC-CDMA systems with MMSE multiuser detector employing fractional and soft frequency reuse, Elsevier AEU - International Journal of Electronics and Communications, vol. 84, pp. 34-45, 2018.
H. Carvajal, N. Orozco, and C. de Almeida, Mean Bit Error Rate Evaluation of MC-CDMA Cellular Systems Employing Multiuser-Maximum-Likelihood Detector, IEEE Transactions on Vehicular Technology, vol. 66, no. 11, pp. 9838-9851, 2017.
H. Carvajal, N. Orozco, and C. de Almeida, Performance analysis of MC-CDMA cellular systems employing MMSE multiuser detector in presence of own-cell and co-cell interference, AEU - International Journal of Electronics and Communications, vol. 80, pp. 19-28, 2017.
H. Carvajal, N. Orozco, and C. de Almeida, Mean Spectral Efficiency Evaluation of the Uplink of MC-CDMA Cellular Systems, Springer Wireless Personal Communications, vol. 96, no. 3, pp. 4595-4611, 2017.
Conferences
J. Peñaloza, J. Freire, N. Orozco, H. Carvajal, ``Virtual Learning Environments based on Beacons Devices'', IEEE Fifth Ecuador Technical Chapters Meeting (ETCM), Cuenca, Ecuador, 2021.
M. Sfredo, E. Fernandez, H. Carvajal, ``Physical Layer Security in Power-Domain NOMA Using Improper Gaussian Signals'', IEEE Vehicular Technology Conference (VTC-Fall), Norman, OK, USA, 2021.
C. Torres Hinojosa, J. Freire, H. Carvajal, N. Orozco, "An Augmented Reality based E-Learning Tool for Engineering", IEEE Colombian Conference on Communications and Computing (COLCOM) , 2021.
D. Lara, E. Oña, H. Carvajal, N. Orozco, C. Frison, “Bit Error Rate Evaluation of SCMA in Rician Fading Channels Considering Presence of Co-Cell Interference”, IEEE Andescon, 2020.
F. Toapanta, N. Orozco, H. Carvajal, J. Freire, “On the Bit Error Rate of Opportunistic Wireless Systems that Employ Non-Square Quadrature Amplitude Modulations”, Ecuador Technical Chapter Meetings (ETCM), Guayaquil, 2019.
C. Frison, H. Carvajal, C. de Almeida, “MC-CDMA and SCMA Performance Evaluation in 100% and 200% Load Factor Scenarios”, Ecuador Technical Chapter Meetings (ETCM), Guayaquil, 2019.
F. Almeida, H. Carvajal and N. Orozco, “GLRT Detection of Nonfluctuating Targets in Background Noise Using Phased Arrays”, International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob), Spain, 2019.
H. Carvajal, N. Orozco, and C. de Almeida, “On the Bit Error Rate of OFDMA Employing Short Cyclic Prefix and Maximal Ratio Combining”, IEEE Colombian Conference on Communications and Computing (COLCOM), Colombia, 2019.
C. Frison, H. Carvajal, C. de Almeida, “MC-CDMA and SCMA Performance and Complexity Comparison in Overloaded Scenarios”, IEEE Colombian Conference on Communications and Computing (COLCOM), Colombia, 2019.
M. Baquero, M. Gavela, I. Sánchez, N. Orozco, H. Carvajal, “Design and Implementation of a Panic Alert System to Notify Theft Events”, ICAETT 2019: Advances in Emerging Trends and Technologies, Part of the Advances in Intelligent Systems and Computing book series, 2019.
H. Carvajal, N. Orozco, and C. de Almeida, BER Analysis of Overloaded MC-CDMA Cellular System Employing Sphere Decoder in Non-Ideal Sectorization Scenario, IEEE 13th Wireless and Mobile Computing, Networking and Communications (WiMob), Roma, Italia, 2017.
N. Orozco, H. Carvajal, and C. de Almeida, “A hybrid transmission scheme employing opportunistic transmission and multiuser diversity”, IEEE 13th Wireless and Mobile Computing, Networking and Communications (WiMob), Roma, Italia, 2017.
H. Carvajal, N. Orozco, and C. de Almeida, On the Performance of MC-CDMA Cellular Systems Employing Multiuser Decorrelating Detector and Antenna Array, IEEE 84th Vehicular Technology Conference (VTC-Fall), Montreal, Canadá, 2016.
N. Orozco, H. Carvajal, and C. de Almeida, “Performance Analysis of Opportunistic Systems Employing Maximal Ratio Combining and Antenna Array”, IEEE 84th Vehicular Technology Conference (VTC-Fall), Montreal, Canadá, 2016.
N. Orozco, H. Carvajal, G. Olmedo, R. León, C. de Almeida, UMTS/HSPA and LTE cellular systems: On the frequency bands and the bit error rate, IEEE Colombian Conference on Communications and Computing (COLCOM), Cartagena, Colombia, 2016.
H. Carvajal, N. Orozco, and C. de Almeida. “On the Performance of Maximal Ratio Combining and Maximum Likelihood Detection in M-QAM/MC-CDMA Systems”. International Telecommunications Symposium, São Paulo, Brasil, 2014.
H. Carvajal, N. Orozco, and C. de Almeida. “Performance analysis of MC-CDMA systems employing maximal ratio combining and uniform linear antenna array”. International Telecommunications Symposium, São Paulo, Brasil, 2014.
N. Orozco, H. Carvajal, and C. de Almeida. “On the performance of a CDMA opportunistic system in Rayleigh fading channel with inter-cell and co-cell interference”. International Telecommunications Symposium, São Paulo, Brasil, 2014.
H. Carvajal, and C. de Almeida. “Performance analysis of MC-CDMA systems in Rayleigh fading channel with Inter-cell and Co-cell interference”. IEEE Latin-America Conference on Communications, Santiago, Chile, 2013.