Diane Kiwior

Routing Protocol Performance over Intermittent Links

Communications among mobile, tactical nodes presents a major military challenge. The use of MANET (Mobile Ad Hoc Network) protocols provides a possible solution for military nodes, including those in an airborne network. However MANET research has primarily focused on ground-based studies, using vehicular speeds and in many cases random mobility patterns. Nodes of an airborne network travel at speeds significantly faster than ground vehicles, and fly in coordinated paths not modeled by random mobility. In addition, the quality of the radio links for airborne nodes varies with time, due to interference, range, or antenna occlusion when banking. These characteristics make it impossible to extrapolate existing MANET research results to the airborne network. In this paper we present a simulation evaluation of MANET protocol performance for an airborne environment, with the intent to identify a routing protocol that can best deal with the dynamics of an airborne network. A scenario involving widebody aircraft trajectories was modeled in OPNET. Intermittent link outages due to aircraft banking were modeled by use of a notional radio link, antenna model, and modified OPNET source code that reflects positional antenna gain, including antenna occlusion when an aircraft banks. Within this scenario environment, four MANET protocols (AODV, TORA, OLSR, OSPFv3-MANET) were run on the airborne nodes with metric collection of protocol overhead, packet delivery ratio, and packet delay. Simulation results and analysis of the protocol performance for an airborne network are presented here. Additional issues and future areas of research are also identified.

Reliable User Datagram Protocol for airborne network

Applications operating over airborne networks are known to perform quite sub-optimally. Transmission Control Protocol (TCP) based applications often experience very low data throughput [1], while the User Datagram Protocol (UDP) based applications suffer high packet loss as well as out-of-order delivery [2]. This is due to the high Bit Error Rate (BER) nature of the wireless links and the high mobility of airborne nodes. Though TCP and UDP have performed well in wired networks, their original design did not take into consideration the characteristics seen in airborne networks thus resulting in their relatively poor performance. In this research, we implemented an OPNET model of the Reliable User Datagram Protocol (RUDP) as proposed in the IETF Internet-Draft in 1999 [3] with extensions to take into consideration the nature of airborne network characteristics. We then analyzed the performance and its applicability to airborne network scenarios. We also provide performance comparison of the enhanced RUDP against the TCP, UDP, and the standard RUDP counterparts.

Performance analysis of SNMP in airborne tactical networks

SNMP, SNMPv2 and SNMPv3 are the standard protocols for network management in traditional wired networks. New RFCs have updated SNMP, but it remains focused on high-availability, high-bandwidth networks. In the dynamic MANET of tactical edge networks, fast-moving aircraft and terrain obscuration combine to create conditions where traditional SNMP is less effective. In this paper, we propose innovative ways to improve SNMP agent/manager interactions, specifically addressing the limitations of a bandwidth constrained tactical edge network. We will analyze the performance improvements using a variety of aggregation techniques of multicast, reliable multicast and aggregation techniques to enhance the SNMP agent/manager interactions thus conserving bandwidth but still monitor and provide network situational awareness to the war fighter. Performance analysis will be conducted through a combination of simulation and emulation environments, and the results will be discussed.

Performance analysis for SIP based VoIP services over airborne tactical networks

In recent years the Department of Defense has aggressively invested in development of an Internet Protocol (IP) based network that interconnects mobile air platforms and ultimately will also connect to the Global Information Grid (GIG) as part of its Net-Centric Warfare initiatives. One of the major visions for the IP based networks is to support interoperable voice communication amongst heterogeneous airborne platforms using Voice over IP (VoIP) technology. In this study, we investigate the performance of the ubiquitous Session Initiation Protocol (SIP), a signaling protocol used by VoIP, in the context of the high loss, high latency, bandwidth constrained Airborne Network environments, and perform an in-depth analysis on various deployment scenarios for SIP-based VoIP services using OPNET System in the Loop (SITL) capability.12

Performance improvements to NETCONF for airborne tactical networks

Network configuration (NETCONF) is a widely used protocol to deploy configuration of network devices. NETCONF uses different transport layer protocols like secure shell (SSH), simple object access protocol (SOAP), or blocks extensible exchange protocol (BEEP) (IETF RFCs 4742 through 4744), and assumes availability of a high bandwidth network for successful configuration deployment. In a dynamic MANET tactical edge network consisting of fast-moving aircraft and terrain obscuration, conditions exist where traditional NETCONF may be less effective and eventually fails to provide guaranteed services to the war fighter. In this paper, we will look at the performance of NETCONF in a limited bandwidth constrained environment with periods of high packet loss. We will also consider the performance effect of using other compression algorithms and binary XML to reduce the amount of configuration data that is sent. Finally, we will study the usage of UDP-based NETCONF transport to improve the performance of NETCONF. By using UDP, data can be delivered more quickly than in a TCP-based transport. The performance analysis of such an airborne network as applied to different tactical scenarios with hundreds of assets will be accomplished through simulation.

Interdomain Routing for Mobile Nodes

In this paper, we investigate the issues related to the use of a BGP (Border Gateway Protocol) backbone to provide connectivity between mobile nodes, with a specific focus on nodes within an airborne network domain. Research efforts have developed multiple MANET (Mobile Ad hoc Network) protocols to provide routing for mobile nodes. In an airborne network environment, however, there may not be a dense enough concentration of nodes within radio range to provide the connectivity needed for effective use of a MANET protocol. In addition, aircraft within radio range of other nodes will experience intermittent and varying quality radio signals due to banking, interference, or Doppler effects. BGP is the de facto standard in use today to provide terrestrial internetworking routing among Autonomous Systems (AS) despite well known problems. BGP configuration can be complex and has convergence issues but the BGP capability to handle large numbers of routes makes it invaluable. In addition to its use in terrestrial internetworking, BGP has been identified as the routing protocol for the Transformational Satellite Communications System (TSAT) Network. Given the BGP networks in a satellite network above and a terrestrial network below an airborne network, it is important to understand the issues of connecting via BGP for airborne nodes. This paper summarizes the results of lab experiments evaluating use of a BGP network for an alternate routing path between aircraft when there is no other connectivity within their airborne routing domain.

Policy management in airborne tactical networks

Policy management in a traditional IP network is accomplished by employing Policy Enforcement Points (PEP) and Policy Decision Points (PDP). Policy management has a configuration model and an outsourcing model. In a configuration model, a PDP will send new policies to a PEP to enforce. In an outsourcing model, a PEP will contact a PDP for a decision as to admit or deny traffic. In dynamic airborne tactical edge networks, fast-moving aircraft and terrain obscuration combine to create conditions where traditional policy management may be less effective to be deployed and fielded. In this paper, we study the efficacy of the configuration model in a dynamic Mobile Ad-hoc Network (MANET) by trying to answer the following questions: How quickly can we rectify a network problem by deploying new policies? Is it possible to deploy a new policy if the problem restricts communication between PDP and PEP? We will also study a case where a PEP will contact a PDP to decide on granting or denying a resource reservation request as applicable to the Resource Reservation Protocol (RSVP). This study will also consider the usage of advanced and aggregated RSVP (A-RSVP and AR-RSVP) protocols for making resource reservations. Modifications to the policy enforcement algorithms will be proposed to improve and meet end-to-end Service Level Agreements. The performance analysis in a simulation environment will be conducted for various tactical edge network scenarios.

Advanced Resource Reservations for QoS in Airborne Tactical Networks

In this paper we analyze the performance of an end-to-end bandwidth reservation scheme like RSVP with advanced reservations in MANET and tactical airborne networks. The performance of standard RSVP and ARSVP is also investigated. We find that in certain types of typical tactical airborne networks RSVP is useful in providing enhanced QoS. ARSVP and to a greater extent, the proposed advanced reservation scheme enhances the end-to-end QoS guarantee in highly dynamic environments.

Models for Network Services in Airborne Tactical Networks

The traditional model of client server interaction in network services such as DNS, LDAP, and RTP does not perform well in dynamic MANET environments including airborne tactical networks. In this paper, we evaluate two general mechanisms that may be used for network services in such dynamic MANET environments. The key difference between the two mechanisms is in triggering the search for new servers so that the interruption to server reachability observed by a client is reduced. The first mechanism initiates the search when the route cost increases beyond a threshold. The second mechanism triggers the search when a more sensitive measure such as RTT increases beyond a preset threshold.

Enable VoIP survivability for future tactical Airborne Networks

Modern Line of Sight (LOS) radio technologies including software defined radios are the fundamental building blocks of the future game-changing High Speed and High Capacity Internet Protocol based Airborne Networks (HSCAN) for the U.S. military. The Air Force currently has multiple ongoing initiatives to develop this future HSCAN [1]. The chief capability amongst many others that the Air Force envisions for HSCAN is the Voice over Internet Protocol (VoIP) communication. This paper discusses the challenges of operating the current VoIP standard technologies over HSCAN networks and proposes collective techniques to overcome these challenges to make VoIP operable over HSCAN.