@conference {
	title = {Return Channel Performance Evaluation of Enhanced SAMA VSAT with FMCSA and ACM Capability},
	author = {Perumal, Senni., Baras, John S., Roy-Chowdhury, Ayan., Petluri, Hemant S., Robinson, Mitch.},
	year = {2011},
	month = {10/2011},
	abstract = {In this paper, we describe our work on developing and evaluating detailed OPNET simulation models of an enhanced Very Small Aperture Terminal (VSAT) satellite Internet gateway and an enhanced satellite hub based on Cerona SkySPAN technology with capacity and latency optimizations in the return channel so as to allow significantly higher number of users and a better user experience. The Cerona SkySPAN technology uses Digital Video Broadcast via Satellite 2nd standard (DVB-S2) in the forward channel and Spread Aloha Multiple Access (SAMA) protocol in the return channel. We augment the SAMA return channel protocol with Fast Multi-Channel Slotted Aloha (FMCSA) protocol and Adaptive Coding and Modulation (ACM). FMCSA combines Multi-Channel Slotted Aloha (MCSA) with packet level forward error correction (FEC) for new messages and scheduled retransmissions for partially received messages. This protocol increases the maximum possible throughput of SAMA, thus supporting higher number of users. FMCSA also reduces the delay of multi-slot short messages (e.g., HTTP requests) while providing more robust delay performance with respect to load fluctuations, thus resulting in a better user experience. We incorporate Adaptive Coding and Modulation in the return channel in order to automatically adapt the coding and modulation to changing channel conditions so as to ensure remote data service irrespective of the channel degradation due to interference, rain fade or other conditions. We show via OPNET simulations that the enhanced SAMA VSAT with FMCSA and ACM improves the throughput, latency and robustness of the SkySPAN SAMA system. We also compare, via OPNET simulations, the enhanced SAMA system (with FMCSA and ACM) with a DVBRCS system to show improvements in user experience.},
	address = {Palermo, Italy},
	booktitle = {17th Ka and Broadband Communications, Navigation and Earth Observation Conference},
	pages = {pp. 417-424}
}
@conference {
	title = {Studying Real-time Traffic in Multi-hop Networks Using the EMANE Emulator: Capabilities and Limitations},
	author = {Jain, Kaustubh., Roy-Chowdhury, Ayan., Somasundaram, Kiran K., Wang, Baobing., Baras, John S.},
	year = {2011},
	month = {03/2011},
	abstract = {In this paper, we provide an open-source software emulator setup for MANETs and study its fidelity in providing reliable performance estimates for real-time traffic. We emulate the IEEE 802.11 MAC/PHY (DCF) using the EMANE software emulator deployed on a cluster and run experiments for different multi-hop wireless scenarios. As an instance, we study the performance of real-time streaming media over a mesh network supported by OLSR. We also use the setup to analyze the impact of the wireless network on the self-similarity of the traffic.},
	address = {Barcelona, Spain},
	booktitle = {SIMUTools 2011- 4th International Conference on Simulation Tools and Techniques},
	pages = {pp. 93-95}
}
@conference {
	title = {VSAT return Channel Optimizations for Broadband Internet Support in 2-Way Satellite Networks},
	author = {Roy-Chowdhury, Ayan., Baras, John S., Robinson, Mitch.},
	year = {2010},
	month = {10/2010},
	abstract = {In this paper we describe our work on a Very Small Aperture Terminal (VSAT) satellite Internet gateway with capacity and latency optimizations in the return channel so as to allow significantly higher number of users, and a better user experience. The gateway is based on the Cerona SkySPAN technology which uses the Digital Video Broadcast via Satellite 2nd standard (DVB-S2) in the forward channel, and single-channel slotted Aloha protocol in the return channel. In this paper we describe the Spread Aloha Multiple Access (SAMA) protocol which we implement in the return channel. The SAMA protocol promises to deliver high speeds at a third of the latency compared to competing technologies like DVB-RCS (multi-frequency TDMA), while allowing the same number of users in 3MHz bandwidth as is possible in TDMA using 36MHz. We also describe the implementation of the Fast Multi-channel Slotted Aloha (FMCSA) protocol that will co-exist with SAMA in the return channel. FMCSA combines slotted Aloha random access with packet level forward error correction (FEC) for new messages and scheduled retransmissions for partially received messages. Due to the parity packets sent in FMCSA, more load is offered to the channel than in SAMA to achieve the same throughput. The delay performance of FMCSA is also much more robust to load fluctuations than SAMA. The combination of SAMA and FMCSA improves the robustness and throughput of the SkySPAN return channel and reduces the channel latency, while supporting significantly higher number of users, in comparison to the competition.},
	address = {Milan, Italy},
	booktitle = {16th Ka and Broadband Communications Conference},
	pages = {pp. 479-486}
}
@conference {
	title = {Probabilistic Non-Repudiation for Source Authentication with TESLA Certificates in Hybrid Satellite/Wireless and Performance Analysis of the Authentication Protocol},
	author = {Roy-Chowdhury, Ayan., Baras, John S.},
	year = {2009},
	month = {09/2009},
	abstract = {In this work, we describe a novel non-repudiation mechanism for an authentication protocol based on the extended TESLA certificate construct. With the non-repudiation mechanism, the authentication protocol is ideally suited for source authentication of low-powered nodes that participate in group communication in hybrid satellite/wireless networks. Security is a necessary parameter in hybrid wireless networks (consisting of groups of terrestrial wireless nodes interconnected by a satellite overlay) if the communication between a pair of nodes, or amongst a group of nodes, is to be protected from unauthorized The focus of our research work is on user authentication and message integrity protocols, which are required to enable communications and ensure that messages between communicating nodes are correctly delivered. This is a non-trivial problem in group communication, where authentication has been traditionally done using asymmetric cryptographic techniques such as public key certificates and digital signatures. However, such asymmetric techniques can be very expensive in terms of processing power and node energy for wireless nodes in hybrid networks. As a solution to this problem, we have proposed a new class of lightweight, symmetric key certificates called extended TESLA certificates, and we have designed an energy-efficient source authentication protocol for group communication that utilizes the infrastructure present in hybrid satellite networks. In our authentication protocol based on the extended TESLA certificate, we propose to add non-repudiation by taking advantage of the satellite infrastructure and the proposed mechanism of key disclosure by proxy. This is a major improvement over previous authentication algorithms based on TESLA, which does not provide for non-repudiation due to the symmetric nature of the underlying cryptographic primitive, Message Authentication Codes. In this paper, we describe the mechanism by which non-repudiation is achieved in our authentication protocol. The non-repudiation is probabilistic in nature, and we analyze the tradeoff between the degree of non-repudiation and the overhead due to the additional information necessary for non-repudiation. Furthermore, through simulations, we compare the performance between the basic authentication protocol and authentication with non-repudiation, and also compare the latter to public key-based schemes.},
	address = {Sardinia, Italy},
	booktitle = {The Ka and Broadband Communications Conference Navigation and Earth Observation Conference 2009 (KaConf2009)},
	pages = {pp.1-8},
	organization = {Cagliari}
}
@conference {
	title = {Performance-aware Security of Unicast Communication in Hybrid Satellite Networks},
	author = {Roy-Chowdhury, Ayan., Baras, John S.},
	year = {2009},
	month = {06/2009},
	abstract = {In this work, we address the performance problems that arise when unicast security protocols IPSEC and SSL are applied for securing the end-to-end communication in hybrid satellite networks. Satellite networks use TCP and HTTP performance-enhancing proxy servers to overcome the adverse
effect of the large delay-bandwidth product of the satellite channel. However, the proxy servers cannot function when IPSEC and SSL are used for secure unicast communication in hybrid satellite networks. We, therefore, propose the use of the Layered IPSEC (LES) protocol as an alternative to IPSEC for networklayer security. We describe a modification to the Internet Key Exchange protocol if dynamic key establishment is needed for
Layered IPSEC. For application-level security of web browsing with acceptable end-to-end delay, we propose the Dual-mode SSL protocol (DSSL) to be used instead of SSL. We describe how LES and DSSL protocols achieve the desired end-to-end communication security while allowing the TCP and HTTP proxy servers to function correctly. Through simulation studies, we quantify the improvement in performance that is achieved using
our proposed protocols, compared to traditional IPSEC and SSL.},
	address = {Dresden, Germany},
	booktitle = {IEEE ICC 2009 Communication and Information Systems Security Symposium},
	pages = {pp.1-6}
}
@conference {
	title = {A Lightweight Certificate-based Source Authentication Protocol for Group Communications in Hybrid Wireless/Satellite Networks},
	author = {Roy-Chowdhury, Ayan., Baras, John S.},
	year = {2008},
	month = {11/2008},
	abstract = {In this paper, we describe an efficient authentication protocol for group communication in hybrid wireless networks with a satellite overlay. The proposed protocol uses a new class of lightweight, symmetric-key certificates called TESLA certificate. The certificates bind the identities of the senders to the anchor elements of their key chains; messages from the senders are authenticated by MACs computed with keys from the chain. The satellite is used as the Certificate Authority to generate the certificates. The satellite also acts as the proxy for the senders in disclosing the MAC keys to the receivers in the network. Due to the use of symmetric MAC functions, the proposed protocol is much less expensive in terms of node processing power and energy compared to digital signatures. The use of the satellite as the CA and the proxy allows strong security mechanisms and fast message verification. Through analysis, we show that the protocol is secure against malicious adversaries. We also estimate of the performance of the protocol in comparison to public key-based digital signatures.},
	address = {New Orleans, LA},
	booktitle = {IEEE Global Communications Conference (IEEE Globecom 2008)},
	pages = {pp. 1-6}
}
@conference {
	title = {Performance Modeling of Hybrid Satellite/Wireless Networks Using Fixed Point Approximation and Sensitivity Analysis of the Performance Models for Network Design},
	author = {Roy-Chowdhury, Ayan., Tabatabaee, Vahid., Baras, John S.},
	year = {2008},
	month = {09/2008},
	abstract = {In this work, we propose a new analytical method for modeling and estimating the performance of hybrid networks that are comprised of terrestrial wireless networks interconnected by a satellite overlay. We take advantage of the natural hierarchy present in the hybrid architecture to split the network into multiple levels based on the node and link characteristics. For the lower level of terrestrial wireless nodes, we use a simple approximate (throughput) loss model that couples the physical, MAC and routing layers. The model provides quantitative statistical relations between the loss parameters used to characterize multiuser interference and physical path conditions on the one hand and traffic rates between origin-destination pairs on the other. For the higher layer consisting of the terrestrial gateway nodes interconnected by the satellite overlay, we use a simple satellite channel bit error loss model coupled with a channel access protocol, to derive a similar relationship between traffic arrival rate and the link loss. We use the technique of hierarchical~reduced loss network model, adapted for packet-switched networks, to create a reduced load network model for the hybrid network that connects the packet arrival rates in the different levels with the associated physical and link loss rates. We then apply a fixed point approximation approach for this set of relations to derive a solution that converges to a fixed point for the given set of parameters, while satisfying all the equations in the set. The result is an implicit model of the selected performance metric parameterized by the design variables. We apply the technique of Automatic Differentiation to the performance models obtained through the fixed point approximation and analyze the sensitivity of the performance metrics to variations in the selected network parameter. We thus develop a methodology for parameter optimization and sensitivity analysis of protocols to aid in the design of hybrid networks. We demonstrate the effectiveness of our approach through simulation results, compared with results from discrete event simulations on identical network topology.},
	address = {Matera, Italy},
	booktitle = {Ka and Broadband Communications Conference},
	pages = {pp. 245-253}
}
@conference {
	title = {Improving Network Performance in Hybrid Wireless Networks Using a Satellite Overlay},
	author = {Roy-Chowdhury, Ayan., Baras, John S.},
	year = {2007},
	month = {09/2007},
	abstract = {Large wireless networks have the ability to provide rapid connectivity in disaster areas~or to interconnect users in far-flung geographical locations. However, limitations on performance and robustness have delayed the adoption of such networks. In this paper, we show that by the addition of a satellite overlay network, the performance and robustness of large-scale wireless networks can be greatly improved and thus make their deployment possible. We define a satellite overlay network as consisting of one or more satellite nodes and multiple terrestrial {\textquoteleft}{\textquoteleft}gateway{\textquoteright}{\textquoteright} nodes that have interfaces for both satellite links and terrestrial wireless communication. We divide the terrestrial network into multiple {\textquoteleft}{\textquoteleft}clusters{\textquoteright}{\textquoteright} of wireless nodes, with each cluster being served by one or more gateway nodes. Ordinary terrestrial user nodes reach the gateway node through multi-hop terrestrial paths. We thus propose a design for a hybrid satellite and terrestrial wireless network. Through network modeling and simulation, we show that significant improvement in end-to-end performance is possible in a wireless network when the satellite overlay is present, in comparison to the performance in flat wireless networks. Our results are for both stationary and mobile ground wireless nodes.},
	address = {Turin, Italy},
	booktitle = {13th KA and Broadband Communications Conference},
	pages = {pp. 111-118}
}
@conference {
	title = {Flexible and Dynamic Communication Architecture for Lunar Exploration},
	author = {Zeng, Hui., Roy-Chowdhury, Ayan., Rentz, Nicolas., Hadjitheodosiou, Michael., Baras, John S.},
	year = {2006},
	month = {06/2006},
	abstract = {We present work related to designing a communication network for lunar exploration. We discuss the important requirements for future space missions that influence the design of this network. We list some characteristics of the network, and highlight important issues and constraint related to performance, cost, and future network evolution. We address issues related to efficiency, fairness, end-to-end delay minimization and Quality-of-Service (QoS) framework in order to enable a flexible access and dynamic mission operation. To provide optimal or near-optimal efficient utilization and fair allocation of bandwidth of the downlink channel while guaranteeing specific QoS requirements for different service classes, we propose two-level (long-term static and short-term dynamic) sharing of a slotted high data rate satellite communication link. The long-term optimal bandwidth allocation is implemented to provide per-stream/per-user QoS guarantee and give the inputs to the next level, short-term dynamic bandwidth allocation. In our time-varying short-term bandwidth allocation with threshold regulation, a small portion of bandwidth is still assigned to all active spacecrafts in advance, but most bandwidth is dynamically allocated by the requests from them, per frame, by solving an optimal timeslot scheduling problem.},
	address = {San Diego, CA},
	booktitle = {24th American Institute of Aeronautics and Astronautics},
	pages = {pp. 1-9}
}
@conference {
	title = {An Authentication Framework for Hybrid Satellite Network with Resource-Constrained Nodes},
	author = {Roy-Chowdhury, Ayan., Baras, John S., Hadjitheodosiou, Michael.},
	year = {2005},
	month = {11/2005},
	abstract = {The new phase of space exploration involves a growing number of human and robotic space missions to remote planets with varying communication and service requirements. Due to the critical nature of the missions, security is a very important requirement that needs to be addressed. Among primary security requirements are user authentication and message integrity that are needed to ensure that the data in the network is transmitted without unauthorized modifications between the source and destinations, and that data from only authorized network nodes are accepted by other nodes. In this paper we focus on the issue of user authentication and data integrity for a specific space network architecture supporting lunar exploration. We consider a hybrid network consisting of a terrestrial network on Earth, a network on the lunar surface, and a satellite constellation that connects the two surface networks. The lunar network comprises sensor nodes serviced by stationary gateways and mobile robotic vehicles with sensing capability, while the network on Earth is envisioned as a combination of private and public networ:ks. The problem of authentication in this network is co~plex due to the presence of nodes with varying capabilities in terms of computation strength, storage and energy. The nodes on .Earth and the gatewayso n the lunar surfacew ould have higher computationa nd energyc apabilitiesc omparedto the satellites and the sensor nodes. In this situation, an authentication protocol that is optimized to the strengths and limitations of the different classeso f nodesw ould be most suited. We focus on a solution that will operate under the constraints of the space environment (delay, limited energy, limited processing capability at remote nodes). We present a framework for user authentication and data integrity based on an authentication algorithm that makes use of symmetric certificates and hash chains of keys used to compute Message Authentication Codes,to provide asymmetric authentication capabilities to the network nodes. nodes with more resources. We give a detailed description of the authentication protocol we develop for this network and p~ovide an analysis of the security of the protocol by considering various types of passive and active attacks. We also highlight the savings incurred in terms of processing, storage and network bandwidth, which we get in using the proposed protocol in comparison to standard public-key authentication protocols.},
	address = {Wuhan, China},
	booktitle = {International Conference on Spatial Information Technology (ICSIT 2005)},
	pages = {pp. 1-12}
}
@conference {
	title = {Hybrid Networks with a Space Segment - Topology Design and Security Issues},
	author = {Roy-Chowdhury, Ayan., Baras, John S., Hadjitheodosiou, Michael., Rentz, Nicolas.},
	year = {2005},
	month = {10/2005},
	abstract = {In this paper we investigate a hybrid network topology that is suitable for supporting interplanetary communications. We define an architecture comprised of a network of sensor nodes on a remote planetary surface, connected to a hybrid terrestrial network of wired and wireless LANs through a series of satellite relays. All the nodes in the network are IP-addressable and support public and symmetric key cryptography. The resulting network forms a hierarchical hybrid mesh that connects users on Earth to networks on or around a remote planetary surface. We describe the design of the network and present preliminary simulation results illustrating the network performance for various parameters. We also discuss how algorithms for user authentication, message integrity and data confidentiality can be incorporated in the network infrastructure for secure end-to-end communication.},
	address = {Atlantic City, NJ},
	booktitle = {2005 Military Communications Conference (MILCOM 2005),},
	pages = {pp.1414 - 1420}
}
@conference {
	title = {Modeling and Design of a Communication Architecture Supporting Lunar Exploration},
	author = {Roy-Chowdhury, Ayan., Hadjitheodosiou, Michael., Baras, John S., Rentz, Nicolas.},
	year = {2005},
	month = {09/2005},
	abstract = {We discuss some basic requirements and trade-offs for designing a communication network supporting the needs of lunar exploration missions. We describe the unique characteristics of this network and outline a prototype network architecture. The proposed network consists of three distinct segments - a terrestrial network on Earth, a network on the lunar surface, and a space segment comprising a satellite constellation that connect the two surface networks.~We develop a simulation platform that includes the network topology, node orbits and mobility, and test the network performance with different applications and traffic loads. We present simulation results obtained with our models that illustrate the network connectivity and delay for varying satellite orbital patterns and traffic characteristics. We also discuss the requirements and constraints for providing a secure infrastructure for end-to-end communication in space exploration networks~and suggest algorithms and protocols for implementing end-to-end encryption, authentication and secure group communication.},
	address = {Rome, Italy},
	booktitle = {23rd AIAA International Communications Satellite Systems Conference and Exhibit (ICSSC)},
	pages = {pp. 1-10}
}
@techreport {
	title = {Key Management for Secure Multicast in Hybrid Satellite Networks},
	author = {Roy-Chowdhury, Ayan., Baras, John S.},
	year = {2004},
	month = {08/2004},
	abstract = {This paper proposes a design for key management for secure multicast in hybrid satellite networks. Communication satellites offer an efficient way to extend IP multicast services for groups in wide-area networks. In order to be commercially viable, the multicast traffic should be accessible only to paying subscribers. Access control can be achieved by data encryption. This requires secure and efficient methods to generate, distribute and update the keys. Most current key management protocols do not scale well when applied to large dynamic groups in wide-area networks. This paper attempts to solve the above problem for groups in a hybrid network that is composed of terrestrial Ethernet LANs interconnected by ATM-based satellite channels. We investigate current group key management protocols, and design a framework for secure and scalable key management for the multicast routing architecture in the satellite network. The proposed framework is presented in detail, alongwith analysis and simulation results.},
	address = {Toulouse, France}
}
@conference {
	title = {Key Management for Secure Multicast in Hybrid Satellite Networks},
	author = {Roy-Chowdhury, Ayan., Baras, John S.},
	year = {2004},
	month = {08/2004},
	abstract = {This paper proposes a design for key management for secure multicast in hybrid satellite networks. Communication satellites offer an efficient way to extend IP multicast services for groups in wide-area networks. In order to be commercially viable, the multicast traffic should be accessible only to paying subscribers. Access control can be achieved by data encryption. This requires secure and efficient methods to generate, distribute and update the keys. Most current key management protocols do not scale well when applied to large dynamic groups in wide-area networks. This paper attempts to solve the above problem for groups in a hybrid network that is composed of terrestrial Ethernet LANs interconnected by ATM-based satellite channels. We investigate current group key management protocols, and design a framework for secure and scalable key management for the multicast routing architecture in the satellite network. The proposed framework is presented in detail, alongwith analysis and simulation results.},
	address = {Toulouse, France},
	booktitle = {19th IFIP International Information Security Conference (SEC 2000)},
	pages = {pp. 533-548}
}
@techreport {
	title = {Framework for IP Multicast in Satellite ATM Networks},
	author = {Roy-Chowdhury, Ayan., Baras, John S.},
	year = {2004},
	month = {05/2004},
	abstract = {This paper proposes a design for IP multicast routing in hybrid satellite networks. The emergence of IP multicast for Internet group communication has placed focus on communication satellites as an efficient way to extend IP multicast services for groups with distributed membership in wide-area networks. This poses interesting challenges for routing. Satellite networks can have both wired and wireless links and also combine different link-layer technologies like Ethernet and ATM. No proposed IP multicast routing protocol for wired networks offers an integrated solution for such networks. This paper attempts to provide a solution by proposing a design for IP multicast routing in wide-area networks that have terrestrial Ethernet LANs interconnected by ATM-based satellite channels. The paper reviews the multicast services offered by IP and ATM, and proposes a multicast routing framework that combines PIM-SM protocol for terrestrial multicasting with the ATM MARS and VC mesh architecture for multicast routing over the satellite links. Modifications are made to the standard protocols to suit the unique needs of the network being considered. The feasibility of the proposed design is tested by performing simulations. The proposed framework is presented in detail, along with analysis and simulation results.},
	address = {Monterey, California},
	number = {Number: CSHCN TR 2004-8}
}
@conference {
	title = {Framework for IP Multicast in Satellite ATM Networks},
	author = {Roy-Chowdhury, Ayan., Baras, John S.},
	year = {2004},
	month = {05/2004},
	abstract = {This paper proposes a design for IP multicast routing in hybrid satellite networks. The emergence of IP multicast for Internet group communication has placed focus on communication satellites as an efficient way to extend the multicast services for groups with distributed membership in wide-area networks. This poses interesting challenges for routing. Hybrid satellite networks can have both wired and wireless links and also combine different link-layer technologies like Ethernet and ATM. No proposed IP multicast routing protocol for wired networks offers an integrated solution for such networks. This paper attempts to provide a solution by proposing a design for IP multicast routing in wide-area networks that have terrestrial Ethernet LANs interconnected by ATM-based satellite channels. The paper reviews the multicast services offered by IP and ATM, and proposes a multicast routing framework that combines PIM-SM protocol for terrestrial multicasting with the ATM MARS and VC mesh architecture for multicast routing over the satellite links. Modifications are made to the standard protocols to suit the unique needs of the network being considered. The feasibility of the proposed design is tested by performing simulations. The proposed framework is presented in detail, along with analysis and simulation results.},
	address = {Monterey, California},
	booktitle = {22nd AIAA International Communications Satellite Systems Conference and Exhibit (ICSSC)},
	pages = {pp. 1-13}
}
@conference {
	title = {INORA-A Unified Signaling and Routing Mechanism for QoS Support in Mobile Ad Hoc Networks},
	author = {Dharmaraju, Dinesh., Roy-Chowdhury, Ayan., Hovareshti, Pedram., Baras, John S.},
	year = {2002},
	month = {08/2002},
	abstract = {Mobile Ad hoc NETworks(MANET) are characterized by bandwidth constrained wireless links, multiple hops and highly dynamic topologies. Providing QoS support in MANETs is hence a challenging task. This paper presents the design, implementation and evaluation of INORA, which is a network layer QoS support mechanism that makes use of the INSIGNIA in-band signaling mechanism and TORA routing protocol for MANETs. TORA provides multiple routes between a given source and destination. We present an effective coupling between TORA and INSIGNIA to get routes that are {\textquotedblleft}best-able{\textquotedblright} to provide QoS requirements for a flow. INORA also combines congestion control with routing},
	address = {Vancouver, Canada},
	booktitle = {International Conference on Parallel Processing Workshops},
	pages = {pp. 86-93},
	organization = {British Columbia}
}
@techreport {
	title = {Study of OLSR for Real-time Media Streaming over 802.11 Wireless Network in Software Emulation Environment},
	author = {Jain, Kaustubh., Somasundaram, Kiran K., Brian, K Wang., Baras, John S., Roy-Chowdhury, Ayan.},
	year = {2013},
	month = {12/2013},
	abstract = {In this paper we present a setup to study the real-time traffic carrying performance of Optimized Link State Routing (OLSR) protocol using software emulation. We emulate the IEEE 802.11 MAC/PHY using the EMANE software emulator, on a cluster of machines, for different multi-hop wireless scenarios. As an instance of real-world usage scenario, we study the performance of real-time streaming media over a mesh network supported by OLSR. In particular, we study the effect of mobility and background traffic on carried load and jitter. We propose to extend this emulation setup to test the real-time performance of prototype routing protocols such as Stable Path Topology Control (SPTC) and other real-time applications.}
}
@article {
	title = {Energy-efficient Source Authentication for Secure Group Communication with Low-Powered Smart Devices in Hybrid Wireless/Satellite Networks},
	author = {Roy-Chowdhury, Ayan., Baras, John S.},
	year = {2011},
	month = {12/2011},
	abstract = {In this paper, we describe a new class of lightweight, symmetric-key digital certificates called extended TESLA certificates and a source authentication protocol for wireless group communication that is based on the certificate. The certificate binds the identity of a wireless smart device to the anchor element of its key chain; keys from the chain are used for computing message authentication codes (MACs) on messages sourced by the device. The authentication protocol requires a centralized infrastructure in the network: we describe the protocol in a hybrid wireless network with a satellite overlay interconnecting the wireless devices. The satellite is used as the Certificate Authority (CA) and also acts as the proxy for the senders in disclosing the MAC keys to the receivers. We also design a probabilistic nonrepudiation mechanism that utilizes the satellite{\textquoteright}s role as the CA and sender proxy. Through analysis, we show that the authentication protocol is secure against malicious adversaries. We also present detailed simulation results that demonstrate that the proposed protocol is much cheaper than traditional public key-based authentication technologies for metrics like processing delay, storage requirements, and energy consumption of the smart devices.},
	pages = {pp. 1-19},
	volume = {vol. 2011},
	number = {Article ID  392529},
	journal = {EURASIP Journal on Wireless Communications and Networking Special Issue on Security and Resilience for Smart Devices and Applications}
}
@article {
	title = {Security Issues in Hybrid Networks with a Satellite Component},
	author = {Roy-Chowdhury, Ayan., Baras, John S., Hadjitheodosiou, Michael., Papademetriou, Spyro.},
	year = {2005},
	month = {12/2005},
	abstract = {Satellites are expected to play an increasingly important role in providing broadband Internet services over long distances in an efficient manner. Most future networks will be hybrid in nature {\textemdash} having terrestrial nodes interconnected by satellite links. Security is an important concern in such networks since the satellite segment is susceptible to a host of attacks, including eavesdropping, session hijacking, and data corruption. In this article, we address the issue of securing communication in satellite networks. We discuss various security attacks that are possible in hybrid satellite networks and survey the different solutions proposed to secure data communications in these networks. We look at the performance problems arising in hybrid networks due to security additions like Internet Security Protocol (IPSec) or Secure Socket Layer (SSL) and suggest solutions to performance-related problems. We also point out important drawbacks in the proposed solutions and suggest a hierarchical key-management approach for adding data security to group communication in hybrid networks.},
	pages = {pp. 50-61},
	volume = {Vol. 12},
	number = {Issue 6},
	journal = {IEEE Wireless Communications Magazine}
}
@techreport {
	title = {Hybrid Networks with a Space Segment - Topology Design and Security issues},
	author = {Roy-Chowdhury, Ayan., Hadjitheodosiou, Michael., Rentz, Nicolas.},
	year = {2005},
	month = {01/2005},
	abstract = {In this paper we investigate a hybrid network topology that is suitable for supporting interplanetary communications. We define an architecture comprised of a network of sensor nodes on a remote planetary surface, connected to a hybrid terrestrial network of wired and wireless LANs through a series of satellite relays. All the nodes in the network are IPaddressable and support public and symmetric key cryptography. The resulting network forms a hierarchical hybrid mesh that connects users on Earth to networks on or around a remote planetary surface. We describe the design of the network and present preliminary simulation results illustrating the network performance for various parameters. We also discuss how algorithms for user authentication, message integrity and data confidentiality can be incorporated in the network infrastructure for secure end-to-end communication.},
	number = {Number: CSHCN TR 2005-6}
}
@techreport {
	title = {A Certificate-Based Light-Weight Authentication Algorithm For Resource-Constrained Devices},
	author = {Roy-Chowdhury, Ayan., Baras, John S.},
	year = {2005},
	month = {01/2005},
	abstract = {In this work, we analyze and extend a recently proposed design of digital certificates called TESLA certificates. Certificates are a necessary tool in today{\textquoteright}s secure networks to certify the identity of nodes taking part in communication. Most prevalent certificate technologies make use of public-key cryptography. Messages generated by the user are signed using its private key, and the signature can be verified by any node who knows the user{\textquoteright}s public key via its certificate. Signature generation and verification using public-key cryptography is computationally expensive for devices with limited computation power and energy resources. In this situation TESLA certificates can be very useful to certify identity, since they rely on symmetric cryptography which is computationally much more efficient. In this paper we explain the concept of TESLA certificates and provide a preliminary description of proposed modifications to the original algorithm to strengthen its security. We extend the original proposal by combining hash chains with TESLA certificates and come up with an efficient source and message authentication protocol based on symmetric key certificates. We also propose a new type of TESLA certificates called Group Certificates for use in multicast group communication. Through analysis, we show that our protocol is secure against malicious adversaries. We also give an initial estimate of the performance of our algorithm and the related comparison to public-key signatures, and we highlight network scenarios where the TESLA certificates could be particularly useful.},
	number = {Number: CSHCN TR 2005-4}
}
@techreport {
	title = {INORA- A Unified Signaling and Routing Protocol in Mobile AdHoc networks},
	author = {Dharmaraju, Dinesh., Roy-Chowdhury, Ayan., Hovareshti, Pedram.},
	year = {2002},
	month = {01/2002},
	abstract = {Mobile Ad hoc NETworks(MANET) are characterized by bandwidthconstrained wireless links, multiple hops and highly dynamic topologies.Providing QoS support in MANETs is hence a challenging task. Thispaper presents the design, implementation and evaluation of INORA,which is a network layer QoS support mechanism that makes use of theINSIGNIA in-band signaling mechanism and TORA routing protocol forMANETs. TORA provides multiple routes between a given source and destination.},
	number = {Number: CSHCN TR 2002-18}
}
