• Queuing Theory
• Stochastic simulation
• Rural Electrification       
• Traffic modelig & Performance Evaluation

• Ranjit Perera, "The Variance of Delay Time in Queuing System M/G/1 with Optimal Strategy SRPT", AEÜ, Vol. 47 (1993), pp 110-114.
• Ranjit Perera, Friedrich Schreiber, "Distribution function and local correlation of the delay time in queuing system M/G/1-SRPT", AEÜ, Vol. 47 (1993), pp 108-110.
• JR Lucas, HYR Perera, PDC Wijayatunga, DC Wijeratne, T Siyambalapitiya, TAK Jayasekera, "Energy efficient lighting for households: A Survey". SLEMA Journal, Sri Lanka Energy Managers Association, Sri Lanka, Vol. 6 (1995), pp 1-9.
• HYR Perera "Impact of Electrification on Quality of Rural life", Transactions of the IEE Sri Lanka Centre, Volume 1 #1(1996), pp 10-17.
• HYR Perera, "Rural Electrification Policy", OUR Engineering Technology, Open University of Sri Lanka, Volume 3 #1, March 1997, pp 58-61.
• HYR Perera, C Görg, F Schreiber, "Higher Order Local Correlation Coefficients of Occupancy in the Queues M/M/1 and M/M/1/N ", AEÜ, Vol. 52 (1998).
• HYR Perera, "Peak shaving through multi-mode operation of household refrigerators", SLEMA Journal, Sri Lanka Energy Managers Association, Vol. 7 (1998).
• HYR Perera, CVK Periyapperuma, UKDLP Udawatta, , "Technical Standards for Low Cost Distribution of Electricity in Village Hydro Schemes", Transactions of the IEE Sri Lanka Centre, Volume 3 #1 January 2001, pp 29-35.
• Ranjit Perera, Eugen Lamers, Carmelita Görg, , "Optimum Number of Restarts in Multi-Threshold RESTART Simulations", Proceedings of Fourth International Workshop on Rare Event Simulation and related Combinatorial Optimization Problems RESIM/COP'02, 11-12 April 2002, Madrid Spain.
• Ranjit Perera. Andreas Eisenblätter, Erik Fledderus, Carmelita Görg, Michael Schutzow, Stefan Vervijmeren, "Pixel Oriented Mobility Modelling for UMTS Network Simulations", Proceedings of IST Mobile and Wireless Tele-communications Summit 2002, 17-19 June 2002, Thessaloniki, Greece, pp 828-831.
• Ulrich Türke, Ranjit Perera, Eugen Lamers, Thomas Winter, Carmelita Görg, "An Advanced Approach for QoS Analysis in UMTS Radio Network Simulations", Proceedings of ITC18, Berlin Germany, September 2003, pp 91-100.
• Eugen Lamers, Ranjit Perera, Ulrich Türke, Carmelita Görg, "Short Term Dynamic System Level Simulation Concepts for UMTS Network Planning", Proceedings of ITC18, Berlin Germany, September 2003 pp 101-110.
• Luis M. Coreia, Erik R. Fledderus, Ellen Meijerink, Ranjit Perera, Antonio Serrador, Ulrich Türke, Miranda J. G. van Uitert, Thomas Winter, "Identification of relevant parameters for traffic modeling and interference estimation" published in http://momentum.zib.de
• Ulrich Türke, Thomas Winter, Ranjit Perera, Eugen Lamers, Ellen Meijerink, Erik R. Fledderus, Antonio Serrador, "Comparison of different simulation approaches for cell performance evaluation" published in http://momentum.zib.de
• Ulrich Türke, Thomas Winter, Eugen Lamers, Ranjit Perera, "Simulation Scenarios Including Quality of Service Aspects" published in http://momentum.zib.de
• Ulrich Türke, Thomas Winter, Eugen Lamers, Ranjit Perera, Lucio Ferreira, "Evaluation of the Influence of User Mobility on Average Traffic Load" published in http://momentum.zib.de
• Thomas Winter, Ulrich Türke, Eugen Lamers, Ranjit Perera, Antonio Serrafdor, Luis M. Correia "Advanced simulation approach for integrated static and short-term dynamic UMTS performance evaluation" published in http://momentum.zib.de
• DGAK Wijeratna, JR Lucas, J Pieris, HYR perera, "Development of a software package for calculating current rating of medium voltage power cables", Transactions of the IEE Sri Lanka Centre, Volume 5 #1 September 2003, pp 50-57.
• Ranjit Perera, Eugen Lamers, Carmelita Görg , Ulrich Türke, Thomas Winter, "Analysis of Soft-Handover Characteristics in Realistic Urban UMTS Radio Networks", Proceedings of VTC 2004 Spring, IEEE Vehicular Technology Conference, May 2004, Milan. Italy.
• Ulrich Türke, Ranjit Perera, Eugen Lamers, Thomas Winter, Carmelita Görg, "An integrated Simulation Approach for Static and Dynamic UMTS Radio Network Performance Evaluation", Proceedings of the 1st Regional Conference ICT and E-Paradigms. June 2004, Colombo, Sri Lanka, pp 25-30.