Armando L. Caro Jr.
Bio Research Publications Software Resume Pictures Contact Info

BBN  Technologies
		   Logo Network Scientist     (September 2005 - Present)
Internetwork Research Department
BBN Technologies
Cambridge, Massachusetts, USA
  • SELf-forming Extensible luNar EVA network (SELENE)     (February 2008 - present)
      Sponsored by NASA

      Collaborators: Scientific Systems Company, Inc. (SSCI)

      The overall objective of this research effort is to develop the SELENE network for specific usage in the Human Lunar Outpost. We are investigating a hybrid scheme combining Mobile Ad-Hoc Networks (MANETs) and Disruption Tolerant Networks (DTNs) for networking EVA radios in the Human Lunar Outpost.

  • Policy-based Information centric Reliable Ad-hoc Network (PIRANA)     (December 2007 - present)
      Sponsored by DARPA, under the WNAN/WAND program

      Collaborators: Agile Communications, SPARTA, Shared Spectrum Company (SSC), PARC, UC Santa Cruz, U of Pennsylvania, Virginia Tech

      The PIRANA project is developing scalable, adaptive, ad-hoc networks which exploit very inexpensive, yet flexible software radios. Innovative aspects of the program include the incorporation of DTN technology for disconnected operation, dynamic spectrum access for finding and exploiting any available frequencies rather than using pre-allocated frequencies, exploitation of multichannel MIMO, and the use of policy and reasoning techniques to make the right tradeoffs and adaptations for the particular mission. This program will require new ideas and innovations to combine previously isolated technologies in new and synergistic ways. We are working towards a 40 radio demonstration in Dec 2008, a 100 radio demonstration in Dec 2009, and a 1000 radio demonstration in Dec 2010.

  • Survivable Policy Influenced Networking: Disruption-tolerance through Learning and Evolution (SPINDLE)     (December 2006 - present)
      Sponsored by DARPA, under the DTN program

      Collaborators: SUNY-Stony Brook, Lehigh University, SPARTA, Michael Demmer, Terrance Swift

      The SPINDLE II project is developing technologies that enable access to information when stable end-to-end paths do not exist and network infrastructure access cannot be assured. DTN technology makes use of persistence within network nodes, along with the opportunistic use of mobility, to overcome disruptions to connectivity.

  • Adaptive Distributed Radio Open-source Intelligent Network (ADROIT)     (January 2006 - November 2006)
      Sponsored by DARPA, under the ACERT program

      Collaborators: MIT, UCLA, University of Kansas, and Blossom Research

      The ADROIT project is building an open-source software-defined data radio, intended to be controlled by cognitive applications. The goal is to create a system that enables teams of radios, where each radio has its own cognitive controls and the ability to collaborate with other radios, to create cognitive radio teams that dynamically adapt in real-time to environmental conditions.

  • Specialized Network Design and Analysis     (September 2005 - January 2006)
      We are consulting with a customer to design a network to meet their specialized communication needs. Further details are proprietary.

Protocol Engineering Lab Logo
U of Delaware Logo
Graduate Research Assistant     (June 1998 - May 2005)
Undergraduate Research Assistant     (June 1996 - May 1998)
Protocol Engineering Lab
Computer and Information Sciences Department
University of Delaware
Newark, Delaware, USA
  • End-to-end Fault Tolerance Using Transport Layer Multihoming     (September 2000 - May 2005)
      Advisor: Prof. Paul D. Amer
      Collaborator: Randall R. Stewart (Cisco Systems)

      My dissertation investigated transport layer techniques that improve end-to-end fault tolerance and throughput. Often, access links (for both clients and servers) are a single point of failure for end-to-end reachability. Routing protocols (in particular, BGP) may also take a significant amount of time (often tens of minutes) to converge on a new route when a link failure is detected. Multihoming support at the transport layer addresses both types of failures by allowing a transport layer session to bind multiple IP addresses at each endpoint. This feature provides both endpoints with multiple paths with which to communicate, and thus the ability to failover to an alternate path when a path failure occurs. I investigated multihoming retransmission policies and failover thresholds with the Stream Control Transmission Protocol (SCTP).

  • NETCICATS for the Web     (September 1999 - August 2000)
      NETCICATS is a Network-Conscious Image Compression And Transmission System developed in UD's PEL lab. Traditional image compression techniques seek the smallest possible size for a given level of image quality. To contrast, network-conscious image compression techniques take into account the fact that a compressed image will be transmitted over a network that may lose and reorder packets. The data is segmented into path MTU-size data units, each of which can be independently decompressed and displayed on its own. Under lossy network conditions, a network-conscious image transmitted with an unordered transport service permits faster progressive display at the receiver than a traditional image transmitted over an ordered transport service. This advantage comes in exchange for a small penalty in overall compression. This research demonstrated (1) the value of considering network characteristics in designing image formats, and (2) the value of unordered transport service.

      I ported much of NETCICATS to a web environment. I developed a Netscape plugin that would fetch network-conscious images using our lab's Universal Transport Library (UTL) and display the images in the browser. UTL allows an application to use a common API for a variety of experimental transport protocols developed in our lab.

  • ReMDoR     (June 1996 - May 1999)
      With Phillip Conrad, I developed an interactive Remote Multimedia Document Retrieval (ReMDoR) system. ReMDoR's architecture resembles the web in that a browser retrieves documents from a server. However, unlike web documents, ReMDoR documents have a time dimension requiring synchronization of audio, still images, graphics, text, pauses, and interactions. The motivation for ReMDoR was to demonstrate the practical benefits of using a partially ordered and partially reliable transport service for multimedia communications. ReMDoR interfaced with our lab's Universal Transport Library (UTL) to dynamically choose among several experimental transport protocols. We designed a specification language for creating multimedia presentations. Using Lex & Yacc, I developed a parser for converting the specification offline into a file format we designed for real-time efficiency. We also designed a transfer syntax that the server used to transmit application data to the fetching browser. The browser was developed in a UNIX environment using the X/Xt/Motif graphics libraries, and I implemented a Network-Conscious GIF image decoder for the browser.

Nokia Logo Research Intern     (Summer 2001)
Nokia Research Center
Helsinki, Finland
  • Initial SCTP Simulation Investigation     (Summer 2001)
      With Janardhan Iyengar, I completed the first two releases of the ns-2 SCTP module, which supported single-homed associations and the partial-reliability (PR-SCTP) extension (known then as the unreliable data mode extension). PR-SCTP allows an SCTP sender to assign different levels of reliability to data so that lost data may be controllably retransmitted only until the reliability threshold for that data is reached. If the reliability threshold is reached for unacked data, the sender abandons that data and notifies the receiver (with Forward TSNs) to do the same.

      Using ns-2, I evaluated SCTP's congestion control algorithms for protocol correctness (with Sack TCP as a guide), and my tests concluded that the algorithms operated properly. I also studied PR-SCTP for correctness and efficiency, and found a few problems with the specification. The first problem was that the congestion window was being incorrectly credited for data that was abandoned. The second problem was that a single loss event could generate many Forward TSNs, which adds overhead and possibly contributes to congestion. The third problem was that the Forward TSNs did not include stream information, and thus often caused ambiguity at the receiver. This ambiguity restricted the receiver from actually abandoning data and caused head-of-line blocking between streams defeating the purpose of SCTP's multistreaming feature. I worked with the PR-SCTP authors to correct the specification.

Telcordia Technologies Logo Research Intern     (Summer 1999 & 2000)
Telcordia Technologies
Morristown, New Jersey, USA
  • ITSUMO QoS     (Summer 2000)
      The Internet Technologies Supporting Universal Mobile Operations (ITSUMO) project is a collaboration between Telcordia Technologies and Toshiba Research formed in February 1999 to develop IP-centric access systems integrating voice, data, and multimedia services for mobile devices. With Jyh-Cheng Chen, I designed the dynamic service level agreement/specification negotiation protocol and the diffserv-based QoS architecture. I implemented a complete prototype of the architecture on 4 mobile laptop hosts and 3 desktops (domain access servers) running Linux. I demonstrated that the mobile hosts could roam freely between the 3 domains while transmitting and receiving video and voice at the negotiated QoS. Each handoff into a new domain required a new IP address using the Dynamic Registration and Configuration Protocol (DRCP), secure client-network registration using the Basic User Registration Protocol (BURP), and finally QoS negotiation and enforcement using our architecture.

  • ITSUMO Secure Registration     (Summer 1999)
      I evaluated several proposals for adding secure registration to a Mobile IP infrastructure, and selected the most appropriate proposal for the ITSUMO architecture. I also extended DHCP to incorporate the same secure registration mechanism. To demonstrate the security functionality, I integrated the security mechanism into an open source implementation of Mobile IP and DHCP. Setting up and experimenting with a Mobile IP testbed helped identify some shortcomings of DHCP for ITSUMO's requirements. Since DHCP was designed for hosts on a fixed LAN and not for roaming hosts, DHCP does not efficiently use scarce wireless bandwidth or provide a link layer independent mechanism for notifying a client that a new address request is needed. These inadequacies of DHCP partially motivated the design of the Dynamic Registration and Configuration Protocol (DRCP).

Armando L. Caro, Jr.