Mariann Hauge

Multi-topology routing for improved network resource utilization in mobile tactical networks

This paper shows how Multi-Topology routing can be used in highly heterogeneous tactical mobile ad hoc networks to improve the network resource utilization. We suggest the usage of a QoS model where a routing protocol maintains several, distinctive network topologies. Each topology is tailored to support either single or multiple QoS-classes. With this model, traffic flows requiring a QoS-class that cannot be supported end-to-end due to limited resources in the present network topology, can be dropped at the source. This QoS architecture reduces the amount of traffic that is forwarded in the network and then dropped somewhere on the route to the destination due to limited network resources. Consequently, some of the scarce network resources are freed for other flows. We demonstrate this mechanism with test and measurements on a highly heterogeneous lab network.

Does higher datarate perform better in IEEE 802.11-based multihop ad hoc networks?

Due to the nature that high datarate leads to shorter transmission range, the performance enhancement by high datarate 802.11 WLANs may be degraded when applying high datarate to an 802.11 based multihop ad hoc network. In this paper, we evaluate, through extensive simulations, the performance of multihop ad hoc networks at multiple transmission datarates, in terms of the number of hops between source and destination, throughput, end-to-end delay and packet loss. The study is conducted based on both stationary chain topology and mesh topologies with or without node mobility. From numerical results on network performance based on chain topology, we conclude that there is almost no benefit by applying the highest datarate when the chain length is 6 hops or more. With node mobility in mesh topology, the benefit of using high datarate diminishes at even shorter number of hops. To explore the main reasons for this behavior, analyses on multihop end-to-end throughput and network k-connectivity have been conducted later in the paper, and correspondingly an auto-rate adaptation algorithm has been proposed.

On improving connectivity and network efficiency in a heterogeneous military environment

In this article, we examine some major challenges to be solved in order to provide efficient end-to-end connectivity, resource management and QoS in a tactical military heterogeneous network (including the mobile edge). We briefly describe a selected set of possible solutions and mechanisms to improve inter-domain and intra-domain networking for the tactical heterogeneous network that will be further studied in the NATO STO IST-124/RTG-061 group “Heterogeneous tactical networks - improving connectivity and network efficiency”.

A realistic military scenario and emulation environment for experimenting with tactical communications and heterogeneous networks

Emulation environments are an effective approach to experimenting with and evaluating network protocols, algorithms, and components. This paper describes a joint effort by the NATO Science & Technology Organizations IST-124 task group to develop and distribute an emulation environment and scenario. The most significant contribution is a vetted and militarily-realistic scenario that provides a rich combination of elements for experimentation. The scenario includes detailed mobility patterns for a battalion-sized operation over the course of two hours, which has been developed by military experts in planning and performing real exercises. The mobility patterns are used to drive the network emulation.

Cross-layer Quality of Service based admission control for Web services

Web services are in widespread use today. This paper discusses Quality of Service (QoS) concepts which are not covered by existing Web services standards, and focuses on application level solutions that will be important building blocks in the future. We implemented a QoS based admission control mechanism, which provides priority based access to the network, while at the same time avoiding overloading the limited network capacity that is available. We use cross-layer mechanisms to combine QoS mechanisms at the network layer with our Web services admission control broker. The preliminary experiments we have performed with Web services over emulated wireless links are discussed.

Evaluation of the scalability of OLSRv2 in an emulated realistic military scenario

Emulation environments are an effective approach to experimenting with and evaluating network protocols, algorithms, and components. This paper describes a joint effort by the NATO Science & Technology Organizations IST-124 Research Task Group to evaluate the scalability of OLSRv1 and OLSRv2 in an emulation environment within a military scenario. The scenario includes detailed mobility patterns for a battalion-sized operation, which has been developed by military experts in planning and executing live exercises. The mobility patterns are used to drive the network emulation. The scalability of OLSRv1 and OLSRv2 (with and without MPR) is assessed by emulating different network sizes and estimating the overhead. Moreover, the unicast packet delivery ratio is calculated for the different OLSR configurations. The results show that with the chosen OLSR update rates, only OLSRv2 with MPR mechanism scales up to 96 nodes.

Coalition Networks for Secure Information Sharing (CoNSIS) (Invited Paper)

The multilateral CONSIS project is related to the migration towards Network Enabled Capabilities (NEC) in the participating countries. As such, CoNSIS aligns with the overarching objective of the NATO NEC (NNEC) to enhance the Alliances ability to federate various capabilities at all levels, military (strategic to tactical) and civilian through networking and information infrastructure. Providing security and efficient network management have been important aspects of this work. The work has been a combination of theoretical studies and field experiments in order to get hands-on experience with the involved technologies. This possibility of addressing radios, networks, SOA, security and management together, has given us knowledge on how the different technologies affect each other and how they may be combined. A follow up project (CoNSIS phase II) is being planned with startup in 2014.

Routing Loops in Mobile Heterogeneous Ad Hoc Networks

Routing loops accounts for a fair share of packet loss in mobile networks, particularly so for heterogeneous mobile networks. Loops occur when nodes build routes based on inconsistent topology databases. The inconsistency is caused by, but not limited to, dissimilar transmission delay, lost signaling messages, mobility, traffic load, and dissimilar frequency for route update messages. The latter cause is a consequence of optimization of control traffic overhead in heterogeneous networks. These networks are networks that consist of links, or network segments, based on radios with unlike transmission technologies. Such networks typically operate in areas that enforce network topologies with non-optimal radio degree for some of the network types. This paper studies the phenomenon of routing loops in mobile heterogeneous networks. It is shown where the loops occur. Methods to reduce the occurrence of the loops, and ways to do local repair, are proposed.

Resilient internetwork routing over heterogeneous mobile military networks

Mobile networks in the military tactical domain, include a range of radio networks with very diverse characteristics and which may be employed differently from operation to operation. When interconnecting networks with dissimilar characteristics (e.g. capacity, range, mobility) a difficult trade-off is to fully utilize the diverse network characteristics while minimizing the cost. To support the ever increasing requirements for future operations it is necessary to provide tools to quickly alter the rule-set during an ongoing operation, due to a change in operation and/or to support different needs. Our contribution is a routing protocol which targets these challenges. We propose an architecture to connect networks with different characteristics. One key point is that low capacity links/networks segments can be included in the heterogeneous network, these segments are protected from overload by controlling where and when signaling/data traffic is sent. The protocol supports traffic policing, including resource reservation. The other key point is the ability to quickly alter the network policy (rules-set) including QoS support during an operation or from operation to operation.

On the performance of packet-pair based path capacity estimation in wireless Ad Hoc networks

Path capacity estimation is used for e.g admission control decisions and rate adaptation. This has resulted in a variety of proposed techniques, mostly for the wired domain. In this paper, we evaluate the accuracy of one packet-pair estimator in a wireless test-bed. We study the performance of the estimator when it is configured to be low-intrusive and also gain experience with its use on different radio transmission technologies and in the presence of traffic-shapers and IP packet fragmentation. The results show that the estimator can give valuable information to an admission control element. However, in a wireless network operating on a contention based shared channel, the packet-pair technique is vulnerable to the scheduling order of the probe packets on multi-hop paths.We also conclude as expected that the estimator can not be used uncritically on all types of transmission technologies.