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The report describes some of the issues involved in the design of integratedradio networks. The performance limits that arise when ATM is used are examined. Gateway design is discussed in terms of their functionality and protocol architectures.
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As new technology is incorporated into weapons and command and control systems, the need for data communications and data processing at the tactical level will increase dramatically. Tactical ground forces are mobile and they oper...
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As new technology is incorporated into weapons and command and control systems, the need for data communications and data processing at the tactical level will increase dramatically. Tactical ground forces are mobile and they operate in a highly stressed environment complete with noise, false messages and attrition of communication resources. Packet radio network (PRNET) is a promising technology that can serve tactical data communication applications if its architecture and the functionality of its protocols is enhanced to allow it to adapt to frequently changing environment and incorporation of a large number of users. Developing such architectures and protocols for large, survivable PRNETs and evaluating their performance were the principal thrusts of this research project. The main advances made in this effort include development of architectures and algorithms that fall in the following categories: (1) Hierarchical architectures and routing for dynamic networks; (2) Multichannel networks--architectures and protocols; (3) Dynamic selection of radio FEC code rate to adapt to channel variations; (4) Broadcast algorithms that provide for transport of messages to multiple destinations amidst topological changes; (5) Self-organizing networks in which the nodes control their local connectivity. The correctness of some algorithms was validated analytically; others were tested by simulations.
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We consider the broadcasting problem in multi-radio multi-channel ad hoc networks. The objective is to minimize the total cost of the network-wide broadcast, where the cost can be of any form that is summable over all the transmis...
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We consider the broadcasting problem in multi-radio multi-channel ad hoc networks. The objective is to minimize the total cost of the network-wide broadcast, where the cost can be of any form that is summable over all the transmissions (e.g., the transmission and reception energy, the price for accessing a specific channel). Our technical approach is based on a simplicial complex model that allows us to capture the broadcast nature of the wireless medium and the heterogeneity across radios and channels. Specifically, we show that broadcasting in multi-radio multi-channel ad hoc networks can be formulated as a minimum spanning problem in simplicial complexes. We establish the NP-completeness of the minimum spanning problem and propose two approximation algorithms with order-optimal performance guarantee. The first approximation algorithm converts the minimum spanning problem in simplical complexes to a minimum connected set cover problem. The second algorithm converts it to a node-weighted Steiner tree problem under the classic graph model. These two algorithms offer tradeoffs between performance and time- complexity. In a broader context, this work appears to be the first that studies the minimum spanning problem in simplicial complexes and weighted minimum connected set cover problem.
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Maintaining a solid radio communication link between a mobile robot entering a building and an external base station is a well-recognized problem. Modern digital radios, while affording high bandwidth and Internet-protocol- based ...
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Maintaining a solid radio communication link between a mobile robot entering a building and an external base station is a well-recognized problem. Modern digital radios, while affording high bandwidth and Internet-protocol- based automatic routing capabilities, tend to operate on line-of-sight links. The communication link degrades quickly as a robot penetrates deeper into the interior of a building. This project investigates the use of mobile autonomous communication relay nodes to extend the effective range of a mobile robot exploding a complex interior environment. Each relay node is a small mobile slave robot equipped with sonar, ladar, and 802.IIb radio repeater. For demonstration purposes, four Pioneer 2-Dx robots are used as autonomous mobile relays, with SSC-San Diego's ROBART III acting as the lead robot. The relay robots follow the lead robot into a building and are automatically deployed at various locations to maintain a networked communication link back to the remote operator. With their on-board external sensors, they also act as rearguards to secure areas already explored by the lead robot. As the lead robot advances and RF shortcuts are detected, relay nodes that become unnecessary will be reclaimed and reused, all transparent to the operator. This project takes advantage of recent research results from several DARPA-funded tasks at various institutions in the areas of robotic simulation, wireless ad hoc networking, route planning, and navigation. This paper describes the progress of the first six months of the project.
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To win a war global in nature, we will have to fight together. One service alone never could, nor will, win by itself. Effective command, control and communications are essential on yesterday's and today's battlefield. However, hi...
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To win a war global in nature, we will have to fight together. One service alone never could, nor will, win by itself. Effective command, control and communications are essential on yesterday's and today's battlefield. However, history has shown us that we have failed to master this element from the Korean Conflict to the invasion of Grenada. Electronic Warfare may hinder or even deny the use of tactical communications. We therefore must have communication systems that are capable against the threat and are interoperable among the Services. The Single Channel Ground and Airborne Radio System (SINCGARS) is one effort to accomplish these goals. The main feature of the SINCGARS radio is that it frequency hops over 2320 discrete channels in a pseudorandom fashion. This paper examines the following: SINCGARS capabilities; initial development plan; changes to that plan caused by other Services requirements; and how these changes affect interoperability.
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Activities during the course of this contract included: design, implementation, and installation of the TESTBED communications systems; design and implementation of the PUCE1 Target Machine; and the design, implementation, and tes...
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Activities during the course of this contract included: design, implementation, and installation of the TESTBED communications systems; design and implementation of the PUCE1 Target Machine; and the design, implementation, and testing of CFA benchmark programs. A number of design and research documents were produced during the course of this work; these are listed in the annotated bibliography of the next section of this report. (Author)
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We address the connectivity of large-scale ad hoc cognitive radio networks, where secondary users exploit channels temporarily and locally unused by primary users and the existence of a communication link between two secondary use...
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We address the connectivity of large-scale ad hoc cognitive radio networks, where secondary users exploit channels temporarily and locally unused by primary users and the existence of a communication link between two secondary users depends not only on the distance between them but also on the transmitting and receiving activities of nearby primary users. We introduce the concept of connectivity region defined as the set of density pairs -- the density of the secondary users and the density of the primary transmitters -- under which the secondary network is connected. Using theories and techniques from continuum percolation, we analytically characterize the connectivity region of the secondary network by showing its three basic properties and analyzing its two critical parameters. Furthermore, we reveal the tradeoff between proximity (the number of neighbors) and the occurrence of spectrum opportunities by studying the impact of the secondary users' transmission power on the connectivity region of the secondary network, and design the transmission power of the secondary users to maximize their tolerance to the primary traffic load.
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This report seeks to inform the reader as to the state of the art of tactical HF data communications. HF Communications provide a large utility in the military arena where ad-hoc communications are required with minimal assets and...
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This report seeks to inform the reader as to the state of the art of tactical HF data communications. HF Communications provide a large utility in the military arena where ad-hoc communications are required with minimal assets and planning. A review of the relevant HF standards is performed, with a discussion on the technical aspects and impacts. A product review is also performed, which informs the reader as to the devices currently available on the market. Finally some recommendations are made as to the standards to use and as to what is happening within the HF market.
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