31,351 research outputs found
Routing in Mobile Ad-Hoc Networks using Social Tie Strengths and Mobility Plans
We consider the problem of routing in a mobile ad-hoc network (MANET) for
which the planned mobilities of the nodes are partially known a priori and the
nodes travel in groups. This situation arises commonly in military and
emergency response scenarios. Optimal routes are computed using the most
reliable path principle in which the negative logarithm of a node pair's
adjacency probability is used as a link weight metric. This probability is
estimated using the mobility plan as well as dynamic information captured by
table exchanges, including a measure of the social tie strength between nodes.
The latter information is useful when nodes deviate from their plans or when
the plans are inaccurate. We compare the proposed routing algorithm with the
commonly-used optimized link state routing (OLSR) protocol in ns-3 simulations.
As the OLSR protocol does not exploit the mobility plans, it relies on link
state determination which suffers with increasing mobility. Our simulations
show considerably better throughput performance with the proposed approach as
compared with OLSR at the expense of increased overhead. However, in the
high-throughput regime, the proposed approach outperforms OLSR in terms of both
throughput and overhead
Architecture for Mobile Heterogeneous Multi Domain Networks
Multi domain networks can be used in several scenarios including military, enterprize networks, emergency networks and many other cases. In such networks, each domain might be under its own administration. Therefore, the cooperation among domains is conditioned by individual domain policies regarding sharing information, such as network topology, connectivity, mobility, security, various service availability and so on. We propose a new architecture for Heterogeneous Multi Domain (HMD) networks, in which one the operations are subject to specific domain policies. We propose a hierarchical architecture, with an infrastructure of gateways at highest-control level that enables policy based interconnection, mobility and other services among domains. Gateways are responsible for translation among different communication protocols, including routing, signalling, and security. Besides the architecture, we discuss in more details the mobility and adaptive capacity of services in HMD. We discuss the HMD scalability and other advantages compared to existing architectural and mobility solutions. Furthermore, we analyze the dynamic availability at the control level of the hierarchy
Carrier Sense Random Packet CDMA Protocol in Dual-Channel Networks
Code resource wastage is caused by the reason that many hopping frequency (FH) sequences are unused, which occurs under the condition that the number of the actual subnets needed for the tactical network is far smaller than the networking capacity of code division net¬working. Dual-channel network (DCN), consisting of one single control channel and multiple data channels, can solve the code resource wastage effectively. To improve the anti-jamming capability of the control channel of DCN, code division multiple access (CDMA) technology was introduced, and a carrier sense random packet (CSRP) CDMA protocol based on random packet CDMA (RP-CDMA) was proposed. In CSRP-CDMA, we provide a carrier sensing random packet mechanism and a packet-segment acknowledgement policy. Furthermore, an analytical model was developed to evaluate the performance of CSRP-CDMA networks. In this model, the impacts of multi-access interference from both inter-clusters and intra-clusters were analyzed, and the mathematical expressions of packet transmission success probability, normalized network throughput and signal interference to noise ratio, were also derived. Analytical and simulation results demonstrate that the normalized network throughput of CSRP-CDMA outperforms traditional RP-CDMA by 10%, which can guarantee the resource utilization efficiency of the control channel in DCNs
Tactical communication systems based on civil standards: Modeling in the MiXiM framework
In this paper, new work is presented belonging to an ongoing study, which
evaluates civil communication standards as potential candidates for the future
military Wide Band Waveforms (WBWFs). After an evaluation process of possible
candidates presented in [2], the selection process in [1] showed that the IEEE
802.11n OFDM could be a possible military WBWF candidate, but it should be
further investigated first in order to enhance or even replace critical
modules. According to this, some critical modules of the physical layer has
been further analyzed in [3] regarding the susceptibility of the OFDM signal
under jammer influences. However, the critical modules of the MAC layer (e.g.,
probabilistic medium access CSMA/CA) have not been analysed. In fact, it was
only suggested in [2] to replace this medium access by the better suited
Unified Slot Allocation Protocol - Multiple Access (USAP-MA) [4]. In this
regard, the present contribution describes the design paradigms of the new MAC
layer and explains how the proposed WBWF candidate has been modelled within the
MiXiM Framework of the OMNeT++ simulator.Comment: Published in: A. F\"orster, C. Sommer, T. Steinbach, M. W\"ahlisch
(Eds.), Proc. of 1st OMNeT++ Community Summit, Hamburg, Germany, September 2,
2014, arXiv:1409.0093, 201
Business Strategies for Transitions towards Sustainable Systems
This paper develops a strategic perspective for business to address persistent sustainability issues by contributing to the innovation of societal systems. Sustainability issues at the level of societal sectors or domains cannot be addressed by single organizations but require co-evolutionary changes in technology, economy, culture and organizational forms. We present the case of transition management in the Netherlands – an approach combining systems analysis with new modes of governance to influence the direction and speed of structural changes towards sustainability – and the activities of two firms working in this new context. From the two specific cases we conceptualize business strategies at different levels to advance sustainable development.transition management;sustainability;business development;systems
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