Browsing by Author "Corson, M. Scott"
Results Per Page
Sort Options
Item An Approach to Fixed/Mobile Converged Routing(2000) Corson, M. Scott; O'Neill, Alan; ISR; CSHCNWe consider a family of routing protocols for networks in which the core topology is essentially fixed by where the end systems may be mobile. We refer to this form of routing as Fixed/Mobile Converged (FMC) routing.This is a mixture of the traditional prefix-routed scenario fo the fixed Internet, and the classical edge mobility scenario that is today supported by cellularnetworks, primarily as part of the cellular technology elements (GSM, GPRS, etc.).
We outline a general architecture for the support of such edge mobility, and present an approach to FMC routing that fits within this architecture. We then present initial simulation resultsillustrating the potential scalability and routing efficiency of this approach.
Item Bandwidth Calculation in a TDMA-based Ad Hoc Network(2000) Zhu, Chenxi; Corson, M. Scott; Corson, M. Scott; ISR; CSHCNBandwidth calculation for Quality-of-Service (QoS) routing in an ad hocnetwork employing Time-Division-Multiple-Access (TDMA) is studied.Certain constraints of TDMA transmission in a wireless network requirescareful scheduling among the nodes in order to achieve conflict-free operations. These constraints also make the calculation of the end-to-end bandwidth along a path non-trivial. These calculationsare essential for QoS routing which requires a certain amount of bandwidth available on a route.
We prove the problem of calculating the maximal end-to-end bandwidth along a given a path in a TDMA network is NP-complete, and develop an efficient bandwidth calculation scheme. We also show how the bandwidth calculation scheme can be usedwith the Ad-hoc On-demand Distance Vector protocol (AODV) to perform QoSrouting.
Item A Channel Probing Scheme for Wireless Networks(2000) Zhu, Chenxi; Corson, M. Scott; Corson, M. Scott; ISRA channel probing scheme for wireless networks is presented. By transmittinga probing signal in a channel and measuring the signal-to-interferenceratio (SIR), a link can estimate the channel condition and predict therequired transmission power without fully powering up. The channel probingscheme can be used as part of a distributed channel allocation algorithm,and simulations have shown that it outperforms some other comparableschemes.Item Distributed Network Simulation Testbed Status Report.(1989) Corson, M. Scott; ISRThe following report describes the facilities, personnel, and simulation effort underway in the Communications and Signal Processing Laboratory (CSPL) of the Systems Research Center (SRC). The intent of the effort is to create a useful simulation and modeling environment to aid in the performance analysis of communication systems. In particular, we describe a distributed network simulation testbed under development to allow rapid prototyping and performance evaluation of distributed network communication protocols. The testbed's design is modular thus allowing it to be built in a piecemeal fashion with each sub- project contributing software modules to be testbed. We first describe the facilities and personnel involved in the simulation effort and then describe the current testbed status and future architecture.Item A Distributed Shared Key Generation Procedure Using Fractional Keys(1998) Poovendran, R.; Corson, M. Scott; Baras, John S.; ISR; CSHCNWe present a new class of distributed key generation and recoveryalgorithms suitable for group communication systems where the groupmembership is either static or slowly time-varying, and must be tightlycontrolled.The proposed key generation approach allows entities whichmayhave only partial trust in each other to jointly generate a shared keywithout the aid of an external third party. The group collectivelygenerates and maintains a dynamic group parameter, and the shared key isgenerated using a strong, one-way function of this parameter.
This schemealso provides perfect forward secrecy. The validity of key generation canbe checked using verifiable secret sharing techniques. The key retrievalmethod does not require the keys to be stored in an external retrievalcenter.
We note that many Internet-based applications may have theserequirements. Fulfillment of these requirements is realized through theuse of fractional keys--a distributed technique recently developed toenhance the security of distributed systems in a non-cryptographicmanner.
Item A Distributed, Object-Oriented Communication Network Simulation Testbed(1992) Corson, M. Scott; ISRThe Distributed Network Simulation Testbed is a research tool designed to aid users in the modeling and performance analysis of communication protocols. The testbed can be used to model communication networks consisting of mobile and/or immobile nodes communicating over broadcast and/or point-to-point channels. Its object-oriented design permits users to utilize previously developed modules and, when necessary, to derive new modules which are subsequently added to the testbed. The testbed, implemented in Sim ++, can run either sequentially on a single processor or in parallel on multiple processors. An object- oriented, graphical user interface allows users to monitor simulation progress for both demonstration and debugging and permits users to graphically construct network simulations from existing testbed components.Item Dynamic Elgamal Public Key Generation with Tight Binding(1999) Poovendran, R.; Corson, M. Scott; Baras, John S.; Baras, John S.; ISR; CSHCNWe present a new distributed, group ElGamal public key generation algorithm which also permits maintenance of a group-specific, dynamic, individual ElGamal public key infrastructure. We parameterize the group with a time-varying quantity that serves as a distributed mechanism for controlling key generation privilege.Our scheme can be viewed as an alternative to polynomial schemes where, at the time of the secret construction step, there has to be a third party or a black box to combine the shares. Also, in polynomial schemes, at the time of combining,the individual shares of the secret have to be revealed to the third party.
In our scheme, the common secret can be generated without ever exposing the individual shares constructing it. We note that many of the recently proposed distributed key management schemes need such group keys for certification and signing purposes.
3rd Annual Conference on Advanced Telecommunications and Information Distribution Research Program (ATIRP)
Item Dynamic ElGamal Public Key Generation with Tight Binding(1999) Poovendran, R.; Corson, M. Scott; Baras, John S.; ISR; CSHCNWe present a new distributed, group ElGamal public key generation algorithm which also permits maintenance of a group-specific, dynamic,individual ElGamal public key infrastructure.We parameterize the group with a time-varying quantity that servesas a distributed mechanism for controlling key generation privilege.
Our scheme can be viewed as an alternative to polynomial schemes where, at the time of the secret construction step, there has to be a third party or a black box to combine the shares. Also, in polynomial schemes, at the time of combining, the individual shares of the secret have to be revealed to the third party. In our scheme, the common secret can be generated without ever exposing the individual shares constructing it.
We note that many of the recently proposed distributed key management~[2-4] schemes need such group keys for certification and signing purposes.
Item An Evolutionary-TDMA Scheduling Protocol (E-TDMA) for Mobile Ad Hoc Networks(2001) Zhu, Chenxi; Corson, M. Scott; ISR; CSHCNA new single channel, time division multiple access (TDMA)scheduling protocol, termed "Evolutionary-TDMA", is presented for mobilead hoc networks. The protocol allows nodes in an ad hoc network toreserve conflict-free TDMA slots for transmission to their neighbors.Two topology-dependent schedules are generated and maintained by theprotocol: a broadcast schedule suitable for network control traffic anda mixed schedule which combines unicast, multicast and broadcasttransmissions for user data traffic. The schedules are frequentlyupdated in an evolutionary manner to maintain conflict-freetransmissions. The protocol executes across the entire networksimultaneously in a fully-distributed and parallel fashion. Trafficprioritization and Quality of Service (QoS) can be supported.Simulations have shown that the performance of the E-TDMA protocol isclose to that of centralized algorithms, while being insensitive tonetwork size in terms of scheduling quality and scheduling overhead. Itis a scalable protocol suitable for very large networks, and networks ofvarying size.Item An Evolutionary-TDMA Scheduling Protocol (E-TDMA) for Mobile Ad Hoc Networks(1998) Zhu, C.; Corson, M. Scott; Corson, M. Scott; ISR; CSHCNA new single channel, time division multiple access (TDMA) schedulingprotocol, termed "Evolutionary-TDMA", is presented for mobile ad hocnetworks. The protocol allows nodes in an ad hoc network to reserveconflict-free TDMA slots for transmission to their neighbors. Two topology-dependent schedules are generated and maintained simultaneously. One is a broadcast schedule inwhich every node has one slot to transmit to all its neighbors. The other isa flexible schedule in which a node can reserve multiple slotsfor transmission of unicast, multicast and broadcast traffic. The schedules are reasonably bandwidth efficient and are frequently updated in an evolutionary manner to maintain conflict-free transmissions. The protocol executes across the entire network simultaneously in a fully distributed and parallel fashion. To react quickly to changing topology and bandwidth demands and to keep overhead low,participating nodes need only coordinate with their one-hop neighbors.Traffic prioritization and Quality of Service (QoS) can be supported with this protocol. Its performance, in terms of both scheduling quality and scheduling overhead, is insensitive to network size. Thus,it is a scalable protocol suitable for very large networks, and networks of varying size.Item A Five-Phase Reservation Protocol (FPRP) for Mobile Ad Hoc Networks(1997) Zhu, Chenxi; Corson, M. Scott; ISR; CSHCNA new single channel, TDMA-based broadcast scheduling protocol, termed the Five-Phase Reservation Protocol (FPRP), is presented for mobile ad hoc networks. The protocol jointly and simultaneously performs the tasks of channel access and node broadcast scheduling. The protocol allows nodes to make reservations within TDMA broadcast schedules. It employs a contention-based mechanism with which nodes compete with each other to acquire the TDMA slots. The FPRP is free of the ``hidden terminal" problem, and is designed such that reservations can be made quickly and efficiently with minimal probability of conflict. It is fully distributed and parallel (a reservation is made through a localized conversation between nodes in a 2-hop neighborhood), and is thus arbitrarily scalable. A ``multihop ALOHA" policy is developed to support the FPRP. This policy uses a multihop, pseudo-Baysian algorithm to calculate contention probabilities and enable faster convergence of the reservation procedure. The performance of the protocol is studied via simulation, and the node coloring process is seen to be as effective as an existing centralized approach. Some future work and applications are also discussed.Item A New Protocol for Scheduling TDMA Transmissions in Mobile Ad Hoc Networks(2001) Zhu, Chenxi; Corson, M. Scott; ISR; CSHCNA new protocol for scheduling TDMA transmission in a mobile ad hoc network isdeveloped. With this protocol, nodes reserve time slots for unicast, multicastor broadcast transmission. The protocol uses contention for nodes to reservetransmission time slots, its operation is distributed and concurrent; thereforeit is independent of the network size and can be used in large or dynamicnetworks. Its performance is studied with simulation and compared with IEEE 802.11 protocol.Item On Satellite Multicast to Heterogeneous Receivers(2001) Tunpan, Apinun; Corson, M. Scott; ISR; CSHCNWe propose a framework for single-source, satellite-based multicast disseminationof bulk files. The framework trades off between reception delay andbandwidth usage and coexists with terrestrial background networktraffic; specifically TCP traffic utilizing a short-termcongestion control mechanism.The framework consists of two major components: 1) a multicastrate scheduling mechanism that uses long-term, end-to-end multicast packet survival statisticsin order to deal with the bandwidth-delay trade-off issue, and 2) afair queueing algorithm that regulates the points where multicast traffic fromthe satellite meets terrestrial background traffic. We show throughsimulation the performance of this framework under a number ofscenarios.The research content in this material will appear in IEEE ICC 2001. Item QoS Routing for Mobile Ad Hoc Networks(2001) Zhu, Chenxi; Corson, M. Scott; ISR; CSHCNA Quality-of-Service (QoS) routing protocol is developed for mobile ad hoc networks. It can establish QoS routes with reserved bandwidth in a network employing TDMA. An efficient algorithmfor calculating the end-to-end bandwidth on a path is developed and usedtogether with the route discovery mechanism of AODV to setup QoS routes.Simulations show that the QoS routing protocol can produce higher throughputand lower delay than its best-effort counterpart.Item A Scalable Extension of Group Key Management Protocol(1998) Poovendran, R.; Ahmed, Sarah N.; Corson, M. Scott; Baras, John S.; ISR; CSHCNThis paper presents a robust, scalable extension to the recently proposed multicast Group Key Management Protocol (GKMP) ([1], [2]), in terms of security administration. The GKMP has two major security related problems: (a) lack of any mechanism to remove a compromised group administrator, and (b) lack of scalability. We are able to remove a compromised single panel member from generating the group keys by setting the panel members with shared authority to generate the group keys. We then introduce the sub-controllers who have all the functionalities of the group control panel except the authority to generate the group keys. The sub-control panel helps scalability of the network in terms of the security operations. The sub-controllers are chosen using a threshold-based clustering algorithm.This paper was presented at the "ATIRP ARL Federated Laboratory 2nd Annual Conference," Feb. 5-6, 1998, University of Maryland, College Park Campus.
Item Tactical and Strategic Communication Network Simulation and Performance Analysis(1997) Baras, John S.; Corson, M. Scott; Doan, Khoa; Jang, Kap D.; Liu, Mingyan D.; Misra, Archan; Xie, H.; ISR; CSHCNWe describe a framework for the efficient modeling and performance evaluation of large networks consisting of mixture of strategic and tactical components. The method emphasizes hierarchical, layered techniques that are fed parametric models at the lower level. In addition to the algorithmic structure, and some initial algorithms we describe an object oriented software architecture that is under development to support these algorithmic methods in a distributed environment.