- Email: [email protected]
Performance Evaluation of Wireless Networks and Communications
Computer Communications 29 (2006) 923–925 www.elsevier.com/locate/comcom
Guest Editorial
Performance Evaluation of Wireless Networks and Communications Welcome to this special issue of the Computer Communications Journal on Performance Evaluation of Wireless Networks and Communications, in which we explore recent research and development results in this important area. The field of wireless systems has witnessed tremendous growth in recent years which makes it the fastest growing segment in the telecommunications industry. As these systems progress with increasing size and performance, it will be able to integrate with other systems enabling them to support mobile computing applications and perform as efficiently as fixed (wired) systems. Due to the difficulties posed by the wireless medium and the increase demand for better and cost-effective services, the area of wireless networks and communications is an extremely rich field for research and development. Performance evaluation of such systems is one of these vital research areas. Moreover, these systems are becoming widespread with many applications and advantages. However, they are very complex. This means that predicting their performance using analytic modeling, simulation analysis as well as measuring their performance using monitors, and other testing scenarios and techniques are crucial to the proper design, tuning, and proper operation and capacity planning [1–5]. This special issue of computer communications journal is dedicated to present state of the art papers in Performance Evaluation of Wireless Networks and Communications. We only accepted eight papers in this special issue out of many submissions from all over the world. The majority of these papers are extended versions of papers accepted in the 2004 International Symposium on Performance Evaluation of Computer and Telecommunication Systems, SPECTS’2004. This means that they have undergone a thorough and a critical review process by experts in the field. Xin and Jamalipour present the research results of their evaluation of throughput performance of TCP in wireless cellular networks in the presence of large delay spikes considering selection of TCP initial congestion window size. This is important a delay spike, caused for
0140-3664/$ - see front matter q 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.comcom.2005.06.011
example by cell reselection, link-layer error recovery, and wireless bandwidth fluctuations, is a prominent feature that is visible in wireless cellular networks, and therefore, its consideration has a major role in research for the future wireless Internet. Moreover, the interaction of delay spike with initial window size is also studied by simulation. The simulation analysis results show that when there is no delay spikes the TCP performance over cellular networks with a bottleneck link is same regardless of enlarging the initial window size. However, if the effect of delay spike were included, increasing the initial window size would actually reduce throughput performance. Lagkas, Papadimitriou, Pomportsis, and, M.S. Obaidat propose a Simple QoS supportive Adaptive Polling (SQAP) protocol for wireless LANs. SQAP operates under an infrastructure wireless LAN, where an Access Point (AP) polls the wireless nodes in order to grant them permission to transmit. The polled node sends data directly to the destination node. The authors consider bursty traffic conditions, under which the protocol operates efficiently. The polling scheme is based on an adaptive algorithm according to which it is most likely that an active node is polled. Moreover, SQAP takes into account packet priorities, thus it supports QoS using the Highest Priority First packet buffer discipline and the priority distinctive polling scheme. The devised protocol combines efficiency and fairness, since it prohibits a singe node to dominate the medium permanently. The performance of SQAP is compared to the efficient learning automata-based polling (LEAP) protocol reported in [6] and results have indicated the superiority of SQAP. Kappes presents experimental studies on the use of MAC multicast in IEEE 802.11b wireless networks. His experiments show that the maximal throughput achievable in such networks is 1.76 Mbps for an 802.11 data rate of 2 Mbps. The paper studies the behavior of VoIP traffic over MAC multicast in such networks in multi-hop scenarios with and without hidden stations. The maximal number of hops for VoIP traffic over 802.11 MAC multicast is four as critical loss ratios are approached for more than four hops. The author reports that while loss turns out to be problematic, round trip time and delay characteristics of the VoIP streams remain acceptable in all scenarios. With hidden stations,
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Guest Editorial / Computer Communications 29 (2006) 923–925
VoIP traffic cannot be relayed with acceptable loss ratios at all. The paper concludes that although VoIP traffic can tolerate some frame loss, MAC multicast can in general only be used if additional higher-layer mechanisms are in place to mitigate MAC frame loss. Moreover, the paper studies the effect of an additional random backoff collision avoidance mechanism in hidden station situations. Viswanath and Obraczka present an analytical model for determining the reachability and reliability of flooding protocols in MANETs. They extended the basic CSMA analysis presented in [7] to derive the probability of successful reception in multi-hop flooding. A network simulator was also used to provide some preliminary simulation results to validate the model. The tests conducted by authors have shown that the results obtained from the analytical model are close to those obtained by the simulator. The preliminary simulation results have indicated that probabilistic flooding can provide similar reliability and reachability guarantees as plain flooding at a lower overhead. Moltchanov, Koucheryavy, and Harju propose an integrated model of a single packetized variable bit rate (VBR) teletraffic source for cellular next generation (NG) All-IP networks. The proposed model integrates two parts: the mobility model and the teletraffic model. The mobility model captures mobility behavior of a single user and is modeled by a Markov chain with finite state space. The teletraffic model captures teletraffic characteristics of call and packet levels and is represented by the superposition of a Markov chain and a discrete-time batch Markovian arrival process (D-BMAP). Mobility and teletraffic models are integrated, such that the whole model is a triply stochastic process for which the D-BMAP framework remains valid. Numerical results of indicate that even in presence of probabilistic dependence between user mobility and its teletraffic demands it is still feasible to estimate the actual value of call and packet level teletraffic demands offered by a single user to cellular NG All-IP networks. The performance evaluation results show that the proposed model allows to predict call and packet level performance degradation experienced by applications in cellular NG All-IP networks under different mobility behavior of nomadic users. Zarai, Boudriga, and Obaidat estimate a new call blocking probability of Universal Terrestrial Radio Access -Time Division Duplex (UTRA TDD) system based on a novel slot allocation scheme. The goal of their work is three-fold. First, it proposes a predictive slot allocation strategy in order to demonstrate to mobile operators that the adaptation of slot allocation to traffic characteristics increases the ratio of the used bandwidth without degradation of the system performance. Second, it proposes an adaptive handoff bandwidth reservation scheme based on the user radio parameters. Their scheme increases the utilization of resources and offers a better
reduction of the call blocking probability. Third, it proposes and develops modeling and simulation techniques to evaluate the performance of the network in terms of a large set of QoS parameters such as the ratio of used bandwidth, new call blocking probability, and handoff blocking probability. Simulation analysis is used to study the effects of the allocation strategy on QoS provision. Lott, Weckerle, and Siebert present a new resource allocation scheme that is based on HIPERLAN/2 standard, which beneficially exploits the potentials of relaying by means of concurrent resource scheduling under control of a central station. Nevertheless, whether multihop communication can be advantageously deployed strongly depends on parameters like noise power, interference, selected modulation and coding scheme, attenuation, and distance between source and destination. These dependencies have been demonstrated by the authors using analytical analysis taking into account link-level simulations. Moreover, the authors investigate the potential gains of MultiHop (MH) communications for a given constellation of terminals with limited number of hops, which are called oligohop connections. Based on Shannon capacity for MH communication and analytical equations the performance with respect to receive power budget and BER, respectively PER has been derived. The results have shown that under several conditions the Smart Direct Link, SDiL outperforms the conventional one-hop connection. However, an oligohop connection does not always perform better than a onehop connection. Because every transmission between nodes needs resources, introduces additional delay, and requires appropriate scheduling, the maximum number of hops should be kept very low. The term ‘oligohop’ is introduced to reflect this characteristic of an end-to-end connection. It is assumed that an oligohop connection consists of up to four single links. The value of four hops is a compromise of potential benefits of relaying on the one hand, which is expected to increase with the possible number of hops, and complexity on the other hand, which increases considerably, too, not forgetting the end-to-end delay and protocol overhead that rises with each hop and transmission for an end-to-end connection. For good links, which have small distances between source and destination and low attenuation coefficients, a one-hop connection should be selected. This is different for high attenuation coefficients above 2.4 and large distances, where the noise power is the dominating factor on a one-hop connection. Under these conditions oligohop connections can mitigate the attenuation by reducing the distance on an individual link. Furthermore, the frequency-reuse can be beneficially exploited by the SDiL appliance. Finally, Papadimitriou introduces a new medium access control protocol for broadcast LANs, which is capable of achieving a high performance under bursty
Guest Editorial / Computer Communications 29 (2006) 923–925
traffic conditions. According to this protocol, the network stations are divided into groups. All the groups are granted permission to transmit in a round-robin basis. The chief goal of the grouping algorithm is to have exactly one ready station in each group. Thus, idle slots and collisions are minimized and a nearly optimal throughput-delay performance is achieved. The grouping of stations is dynamically modified at each time slot according to the network feedback information. Due to the dynamic nature of the grouping scheme, the protocol is capable of being adapted to the sharp changes of the stations’traffic.
Acknowledgements I would like to thank all the authors and reviewers for their contributions and dedicated efforts. Thanks also to the editorial assistants for their fine support. Finally, special thanks go to Jeremy Thompson, Editor of Computer Communications Journal, for hosting this issue.
References [1] P. Nicopolitidis, M.S. Obaidat, G.I. Papadimitriou, A.S. Pomportsis, Wireless Networks, Wiley, New York, 2003. [2] M.S. Obaidat, Recent advances in computer communications networking, Computer Communication Journal 26 (15) (2003) 1723–1726. [3] M. Ould-Khaoua, H. Sarbazi-Azad, M.S. Obaidat, Performance modeling and evaluation of high-performance parallel and distributed systems, Performance Evaluation Journal 60 (1–4) (2005) 1–4. [4] M.S. Obaidat, Advances in performance evaluation of computer and telecommunications networking, Computer Communication Journal 25 (11–12) (2002) 993–996. [5] M.S. Obaidat, Research and Development in Information and Communications technology, 2002 World Bank/UNDP Workshop on Fostering Digital Inclusion—the Role of ICT in Development, 2002. see: http://www.worldbank.org/mdf/mdf4/presspdf/presscurtain.pdf [6] P. Nicopolitidis, G.I. Papadimitriou, Learning automata-based polling protocols for wireless LANs, IEEE Transactions on Communications 51 (3) (2003). [7] L. Wu, P. Varshney, Performance Analysis of CSMA and BTMA protocols in Multihop Networks: Part 1-single channel case, Information Sciences 120 (14) (1999) 159–177.
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Professor Mohammad S. Obaidat is an internationally well known academic, researcher, and scientist. He received his PhD and MS degrees in Computer Engineering with a minor in Computer Science from The Ohio State University, Columbus, Ohio, USA. Dr Obaidat is currently a full Professor of Computer Science at Monmouth University, NJ, USA. Among his previous positions are Chair of the Department of Computer Science and Director of the Graduate Program at Monmouth University and a faculty member at the City University of New York. He has received extensive research funding. He has authored or co-authored five books and over three hundred (300) refereed scholarly journal and conference articles. Dr Obaidat has served as a consultant for several corporations and organizations worldwide and is editor of many scholarly journals including being the Chief Editor of the International Journal of Communication Systems published by John Wiley. In 2002, he was the scientific advisor for the World Bank/UN Workshop on Fostering Digital Inclusion. He was an IEEE (Institute of Electrical and Electronics Engineers) Computer Society Distinguished Visitor/Speaker and has been serving as a National ACM (Association for Computing Machinery) distinguished Lecturer since 1995. Recently, Dr Obaidat was awarded the distinguished Nokia Research Fellowship and the Distinguished Fulbright Scholarship.He has made pioneering and lasting contributions to the multifacet fields of computer science and engineering. He has guest edited numerous special issues of scholarly journals such as IEEE Transactions on Systems, Man and Cybernetics, Elsevier Performance Evaluation, Simulation: Transactions of SCS, Elsevier Computer Communications Journal, Journal of C & EE, and International Journal of Communication Systems. Obaidat has served as the steering committee chair, advisory Committee Chair and program chair of many international conferences. He is the founder of the International Symposium on Performance Evaluation of Computer and Telecommunication Systems, SPECTS and has served as the General Chair of SPECTS since its inception. Obaidat has received a recognition certificate from IEEE. Between 1996 and 1999, he served as an IEEE/ACM program evaluator of the Computing Sciences Accreditation Board/Commission, CSAB/CSAC. Between 1995 and 2002, he has served as a member of the board of directors of the Society for Computer Simulation International. Between 2002 and 2004, He has served as Vice President of Conferences of the Society for Modeling and Simulation International SCS. Prof. Obaidat is currently the Vice President of Membership of the Society for Modeling and Simulation International SCS. He has been invited to lecture and give keynote speeches worldwide. His research interests are: wireless communications and networks, performance evaluation of computer systems, algorithms and networks, telecommunications and Networking systems, high performance and parallel computing/computers, applied neural networks and pattern recognition, information and computer security, security of e-based systems, and speech processing. He is currently on sabbatical leave as Fulbright distinguished Professor and Advisor to the President of Philadelphia University for Research, Development and Information Technology. Prof. Obaidat is a Fellow of the Society for Modeling and Simulation International SCS, and a Fellow of the Institute of Electrical and Electronics Engineers (IEEE).
Guest Editorial
Performance Evaluation of Wireless Networks and Communications Welcome to this special issue of the Computer Communications Journal on Performance Evaluation of Wireless Networks and Communications, in which we explore recent research and development results in this important area. The field of wireless systems has witnessed tremendous growth in recent years which makes it the fastest growing segment in the telecommunications industry. As these systems progress with increasing size and performance, it will be able to integrate with other systems enabling them to support mobile computing applications and perform as efficiently as fixed (wired) systems. Due to the difficulties posed by the wireless medium and the increase demand for better and cost-effective services, the area of wireless networks and communications is an extremely rich field for research and development. Performance evaluation of such systems is one of these vital research areas. Moreover, these systems are becoming widespread with many applications and advantages. However, they are very complex. This means that predicting their performance using analytic modeling, simulation analysis as well as measuring their performance using monitors, and other testing scenarios and techniques are crucial to the proper design, tuning, and proper operation and capacity planning [1–5]. This special issue of computer communications journal is dedicated to present state of the art papers in Performance Evaluation of Wireless Networks and Communications. We only accepted eight papers in this special issue out of many submissions from all over the world. The majority of these papers are extended versions of papers accepted in the 2004 International Symposium on Performance Evaluation of Computer and Telecommunication Systems, SPECTS’2004. This means that they have undergone a thorough and a critical review process by experts in the field. Xin and Jamalipour present the research results of their evaluation of throughput performance of TCP in wireless cellular networks in the presence of large delay spikes considering selection of TCP initial congestion window size. This is important a delay spike, caused for
0140-3664/$ - see front matter q 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.comcom.2005.06.011
example by cell reselection, link-layer error recovery, and wireless bandwidth fluctuations, is a prominent feature that is visible in wireless cellular networks, and therefore, its consideration has a major role in research for the future wireless Internet. Moreover, the interaction of delay spike with initial window size is also studied by simulation. The simulation analysis results show that when there is no delay spikes the TCP performance over cellular networks with a bottleneck link is same regardless of enlarging the initial window size. However, if the effect of delay spike were included, increasing the initial window size would actually reduce throughput performance. Lagkas, Papadimitriou, Pomportsis, and, M.S. Obaidat propose a Simple QoS supportive Adaptive Polling (SQAP) protocol for wireless LANs. SQAP operates under an infrastructure wireless LAN, where an Access Point (AP) polls the wireless nodes in order to grant them permission to transmit. The polled node sends data directly to the destination node. The authors consider bursty traffic conditions, under which the protocol operates efficiently. The polling scheme is based on an adaptive algorithm according to which it is most likely that an active node is polled. Moreover, SQAP takes into account packet priorities, thus it supports QoS using the Highest Priority First packet buffer discipline and the priority distinctive polling scheme. The devised protocol combines efficiency and fairness, since it prohibits a singe node to dominate the medium permanently. The performance of SQAP is compared to the efficient learning automata-based polling (LEAP) protocol reported in [6] and results have indicated the superiority of SQAP. Kappes presents experimental studies on the use of MAC multicast in IEEE 802.11b wireless networks. His experiments show that the maximal throughput achievable in such networks is 1.76 Mbps for an 802.11 data rate of 2 Mbps. The paper studies the behavior of VoIP traffic over MAC multicast in such networks in multi-hop scenarios with and without hidden stations. The maximal number of hops for VoIP traffic over 802.11 MAC multicast is four as critical loss ratios are approached for more than four hops. The author reports that while loss turns out to be problematic, round trip time and delay characteristics of the VoIP streams remain acceptable in all scenarios. With hidden stations,
924
Guest Editorial / Computer Communications 29 (2006) 923–925
VoIP traffic cannot be relayed with acceptable loss ratios at all. The paper concludes that although VoIP traffic can tolerate some frame loss, MAC multicast can in general only be used if additional higher-layer mechanisms are in place to mitigate MAC frame loss. Moreover, the paper studies the effect of an additional random backoff collision avoidance mechanism in hidden station situations. Viswanath and Obraczka present an analytical model for determining the reachability and reliability of flooding protocols in MANETs. They extended the basic CSMA analysis presented in [7] to derive the probability of successful reception in multi-hop flooding. A network simulator was also used to provide some preliminary simulation results to validate the model. The tests conducted by authors have shown that the results obtained from the analytical model are close to those obtained by the simulator. The preliminary simulation results have indicated that probabilistic flooding can provide similar reliability and reachability guarantees as plain flooding at a lower overhead. Moltchanov, Koucheryavy, and Harju propose an integrated model of a single packetized variable bit rate (VBR) teletraffic source for cellular next generation (NG) All-IP networks. The proposed model integrates two parts: the mobility model and the teletraffic model. The mobility model captures mobility behavior of a single user and is modeled by a Markov chain with finite state space. The teletraffic model captures teletraffic characteristics of call and packet levels and is represented by the superposition of a Markov chain and a discrete-time batch Markovian arrival process (D-BMAP). Mobility and teletraffic models are integrated, such that the whole model is a triply stochastic process for which the D-BMAP framework remains valid. Numerical results of indicate that even in presence of probabilistic dependence between user mobility and its teletraffic demands it is still feasible to estimate the actual value of call and packet level teletraffic demands offered by a single user to cellular NG All-IP networks. The performance evaluation results show that the proposed model allows to predict call and packet level performance degradation experienced by applications in cellular NG All-IP networks under different mobility behavior of nomadic users. Zarai, Boudriga, and Obaidat estimate a new call blocking probability of Universal Terrestrial Radio Access -Time Division Duplex (UTRA TDD) system based on a novel slot allocation scheme. The goal of their work is three-fold. First, it proposes a predictive slot allocation strategy in order to demonstrate to mobile operators that the adaptation of slot allocation to traffic characteristics increases the ratio of the used bandwidth without degradation of the system performance. Second, it proposes an adaptive handoff bandwidth reservation scheme based on the user radio parameters. Their scheme increases the utilization of resources and offers a better
reduction of the call blocking probability. Third, it proposes and develops modeling and simulation techniques to evaluate the performance of the network in terms of a large set of QoS parameters such as the ratio of used bandwidth, new call blocking probability, and handoff blocking probability. Simulation analysis is used to study the effects of the allocation strategy on QoS provision. Lott, Weckerle, and Siebert present a new resource allocation scheme that is based on HIPERLAN/2 standard, which beneficially exploits the potentials of relaying by means of concurrent resource scheduling under control of a central station. Nevertheless, whether multihop communication can be advantageously deployed strongly depends on parameters like noise power, interference, selected modulation and coding scheme, attenuation, and distance between source and destination. These dependencies have been demonstrated by the authors using analytical analysis taking into account link-level simulations. Moreover, the authors investigate the potential gains of MultiHop (MH) communications for a given constellation of terminals with limited number of hops, which are called oligohop connections. Based on Shannon capacity for MH communication and analytical equations the performance with respect to receive power budget and BER, respectively PER has been derived. The results have shown that under several conditions the Smart Direct Link, SDiL outperforms the conventional one-hop connection. However, an oligohop connection does not always perform better than a onehop connection. Because every transmission between nodes needs resources, introduces additional delay, and requires appropriate scheduling, the maximum number of hops should be kept very low. The term ‘oligohop’ is introduced to reflect this characteristic of an end-to-end connection. It is assumed that an oligohop connection consists of up to four single links. The value of four hops is a compromise of potential benefits of relaying on the one hand, which is expected to increase with the possible number of hops, and complexity on the other hand, which increases considerably, too, not forgetting the end-to-end delay and protocol overhead that rises with each hop and transmission for an end-to-end connection. For good links, which have small distances between source and destination and low attenuation coefficients, a one-hop connection should be selected. This is different for high attenuation coefficients above 2.4 and large distances, where the noise power is the dominating factor on a one-hop connection. Under these conditions oligohop connections can mitigate the attenuation by reducing the distance on an individual link. Furthermore, the frequency-reuse can be beneficially exploited by the SDiL appliance. Finally, Papadimitriou introduces a new medium access control protocol for broadcast LANs, which is capable of achieving a high performance under bursty
Guest Editorial / Computer Communications 29 (2006) 923–925
traffic conditions. According to this protocol, the network stations are divided into groups. All the groups are granted permission to transmit in a round-robin basis. The chief goal of the grouping algorithm is to have exactly one ready station in each group. Thus, idle slots and collisions are minimized and a nearly optimal throughput-delay performance is achieved. The grouping of stations is dynamically modified at each time slot according to the network feedback information. Due to the dynamic nature of the grouping scheme, the protocol is capable of being adapted to the sharp changes of the stations’traffic.
Acknowledgements I would like to thank all the authors and reviewers for their contributions and dedicated efforts. Thanks also to the editorial assistants for their fine support. Finally, special thanks go to Jeremy Thompson, Editor of Computer Communications Journal, for hosting this issue.
References [1] P. Nicopolitidis, M.S. Obaidat, G.I. Papadimitriou, A.S. Pomportsis, Wireless Networks, Wiley, New York, 2003. [2] M.S. Obaidat, Recent advances in computer communications networking, Computer Communication Journal 26 (15) (2003) 1723–1726. [3] M. Ould-Khaoua, H. Sarbazi-Azad, M.S. Obaidat, Performance modeling and evaluation of high-performance parallel and distributed systems, Performance Evaluation Journal 60 (1–4) (2005) 1–4. [4] M.S. Obaidat, Advances in performance evaluation of computer and telecommunications networking, Computer Communication Journal 25 (11–12) (2002) 993–996. [5] M.S. Obaidat, Research and Development in Information and Communications technology, 2002 World Bank/UNDP Workshop on Fostering Digital Inclusion—the Role of ICT in Development, 2002. see: http://www.worldbank.org/mdf/mdf4/presspdf/presscurtain.pdf [6] P. Nicopolitidis, G.I. Papadimitriou, Learning automata-based polling protocols for wireless LANs, IEEE Transactions on Communications 51 (3) (2003). [7] L. Wu, P. Varshney, Performance Analysis of CSMA and BTMA protocols in Multihop Networks: Part 1-single channel case, Information Sciences 120 (14) (1999) 159–177.
925
Professor Mohammad S. Obaidat is an internationally well known academic, researcher, and scientist. He received his PhD and MS degrees in Computer Engineering with a minor in Computer Science from The Ohio State University, Columbus, Ohio, USA. Dr Obaidat is currently a full Professor of Computer Science at Monmouth University, NJ, USA. Among his previous positions are Chair of the Department of Computer Science and Director of the Graduate Program at Monmouth University and a faculty member at the City University of New York. He has received extensive research funding. He has authored or co-authored five books and over three hundred (300) refereed scholarly journal and conference articles. Dr Obaidat has served as a consultant for several corporations and organizations worldwide and is editor of many scholarly journals including being the Chief Editor of the International Journal of Communication Systems published by John Wiley. In 2002, he was the scientific advisor for the World Bank/UN Workshop on Fostering Digital Inclusion. He was an IEEE (Institute of Electrical and Electronics Engineers) Computer Society Distinguished Visitor/Speaker and has been serving as a National ACM (Association for Computing Machinery) distinguished Lecturer since 1995. Recently, Dr Obaidat was awarded the distinguished Nokia Research Fellowship and the Distinguished Fulbright Scholarship.He has made pioneering and lasting contributions to the multifacet fields of computer science and engineering. He has guest edited numerous special issues of scholarly journals such as IEEE Transactions on Systems, Man and Cybernetics, Elsevier Performance Evaluation, Simulation: Transactions of SCS, Elsevier Computer Communications Journal, Journal of C & EE, and International Journal of Communication Systems. Obaidat has served as the steering committee chair, advisory Committee Chair and program chair of many international conferences. He is the founder of the International Symposium on Performance Evaluation of Computer and Telecommunication Systems, SPECTS and has served as the General Chair of SPECTS since its inception. Obaidat has received a recognition certificate from IEEE. Between 1996 and 1999, he served as an IEEE/ACM program evaluator of the Computing Sciences Accreditation Board/Commission, CSAB/CSAC. Between 1995 and 2002, he has served as a member of the board of directors of the Society for Computer Simulation International. Between 2002 and 2004, He has served as Vice President of Conferences of the Society for Modeling and Simulation International SCS. Prof. Obaidat is currently the Vice President of Membership of the Society for Modeling and Simulation International SCS. He has been invited to lecture and give keynote speeches worldwide. His research interests are: wireless communications and networks, performance evaluation of computer systems, algorithms and networks, telecommunications and Networking systems, high performance and parallel computing/computers, applied neural networks and pattern recognition, information and computer security, security of e-based systems, and speech processing. He is currently on sabbatical leave as Fulbright distinguished Professor and Advisor to the President of Philadelphia University for Research, Development and Information Technology. Prof. Obaidat is a Fellow of the Society for Modeling and Simulation International SCS, and a Fellow of the Institute of Electrical and Electronics Engineers (IEEE).