@conference {
	title = {A Multiple Subset Sum Formulation for Feedback Implosion Suppression over Satellite Networks},
	author = {Akkor, Gun., Baras, John S., Hadjitheodosiou, Michael.},
	year = {2005},
	month = {11/2005},
	abstract = {In this paper, we present a feedback implosion suppression (FIS) algorithm that reduces the volume of feedback information transmitted through the network without relying on any collaboration between users, or on any infrastructure other than the satellite network. Next generation satellite systems that utilize the Ka frequency band are likely to rely on various fade mitigation techniques, in order to guarantee a service quality that is comparable to other broadband technologies. User feedback would be a valuable input for a number of such components, however, collecting periodic feedback from a large number of users would result in the well-known feedback implosion problem. Feedback implosion is identified as a major problem when a large number of users try to transmit their feedback messages through the network, holding up a significant portion of the uplink resources and clogging the shared uplink medium. In this paper, we look at a system where uplink channel access is organized in time-slots. The goal of the FIS algorithm is to reduce the number of uplink time-slots hold up for the purpose of feedback transmission. Our analysis show that the FIS algorithm effectively suppresses the feedback messages of 95\% of all active users, but still achieves acceptable performance results when the ratio of available time-slots to number of users is equal to or higher than 5\%.},
	address = {St. Louis, MO},
	booktitle = {Globecom 2005 Wireless Communications},
	pages = {pp. 3226-3230}
}
@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 = {AeroTCP: A Splitting Transport Protocol for an IP-based Satellite Network Supporting Aeronautical Communications},
	author = {Shang, Yadong., Hadjitheodosiou, Michael., Baras, John S.},
	year = {2005},
	month = {09/2005},
	abstract = {The IP-based Broadband Aeronautical Satellite Network will provide numerous new applications and services for both airspace system operations and passenger communications. However, the performance of data communications protocols and applications over such systems is dramatically degraded, especially the Internet TCP/IP protocol suite. In this paper, we propose a new transport protocols for satellite network supporting Internet and data services. Based on the observation that it is difficult for an end to- end TCP solution to solve the performance problem effectively, we propose a new splitting based TCP protocol, called Aeronautical Transport Control Protocol (AeroTCP), which takes advantage of the specific properties of satellite channel. Our simulation results show that AeroTCP improves satellite channel utilization and fairness.},
	address = {Rome, Italy},
	booktitle = {23rd AIAA International Communications Satellite Systems Conference and Exhibit (ICSSC)}
}
@conference {
	title = {Integrated Packet Level FEC Coding for Bulk Data Transfer Over Satellite Network},
	author = {Akkor, Gun., Baras, John S., Hadjitheodosiou, Michael.},
	year = {2005},
	month = {09/2005},
	abstract = {Packet level forward error correction (FEC) coding has been widely accepted as an efficient way of reducing the number of retransmissions and recovering from packet losses for reliable multicast in satellite networks. While there has been a significant effort in defining packet level FEC schemes that detail the structure, organization and delivery of the encoding packets, little attention has been given to how the physical channel, channel coding, and the downlink power budget affect the design space of these schemes in the context of a satellite network architecture. In this paper, we take a step in this direction, and define the points of interaction between various components and build a simulation environment. Using this simulation setup, we provide design suggestions for integrating FEC coding into reliable multicast transport protocols.},
	address = {Rome, Italy},
	booktitle = {23rd AIAA International Communications Satellite Systems Conference and Exhibit (ICSSC)}
}
@conference {
	title = {Dynamic Resource Allocation for an IP-based Communications Network Supporting Space Exploration},
	author = {Zeng, Hui., Hadjitheodosiou, Michael., Baras, John S.},
	year = {2005},
	month = {09/2005},
	abstract = {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 capability in the next generation NASA space-to-ground IP-based communication infrastructure. In our scenario, the downlink channel of the NASA Tracking and Data Relay Satellite System is shared by a number of spacecraft, which we model as streams with different priority levels going through a common queue and a router. Both the current and future potential architectures for this relay system are addressed. We formulate an optimization problem for long-term static bandwidth allocation and present its solution to serve as initial bandwidth allocation algorithm and periodical regulation approach. Along with it, a hybrid Time Division Multiple Access (TDMA)-based protocol is proposed and then an assignment problem for the short-term dynamic optimal timeslot scheduling is studied. By using simulation, the performance of a suitable Medium Access Control (MAC) protocol with timeslot scheduling is analyzed and compared with that of the existing static fixed-assignment scheme.},
	address = {Rome, Italy},
	booktitle = {23rd AIAA International Communications Satellite Systems Conference and Exhibit (ICSSC)},
	pages = {pp. 1-12}
}
@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}
}
