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Showing papers on "Static routing published in 1969"


Journal ArticleDOI
B. Boehm1, R. Mobley1
TL;DR: A number of research areas are pointed out in which further efforts in the analysis and simulation of adaptive routing techniques will have useful payoffs in the design of future distributed communications systems.
Abstract: The concept of a netted or distributed communications system is significant because it offers a major advantage over conventional communications systems, i.e., a better chance of providing surviving lines of communication after an attack on the system. During and after an attack, however, an effective adaptive routing technique is necessary to adjust the routing tables of the message-switching control system to the changing situation. Previously investigated adaptive routing techniques are shown to be insufficient for the task, and a number of promising alternatives are formulated and investigated such as some stochastic techniques, which use information on messages passing through the network to adjust the tables, and some deterministic techniques, which use dynamic programming or graph-theoretic algorithms to recalculate changes in the tables from observed changes in the network. Each alternative has operational advantages, which make it good for certain types of communications systems, and certain disadvantages if applied to others. Regions of applicability and inapplicability, with respect to the above system parameters, are given for the various techniques. Recommended techniques are specified for two currently proposed applications of distributed communications systems. A number of research areas are pointed out in which further efforts in the analysis and simulation of adaptive routing techniques will have useful payoffs in the design of future distributed communications systems.

29 citations


Patent
30 Jan 1969
TL;DR: In this paper, a traffic routing plan is modified by a traffic controller by a call from a special station, to designate which one of three predetermined routing plans stored in the respective routing words is to be used.
Abstract: A communications network is disclosed wherein the code translation and routing apparatus at each switching center includes a memory having a number of code words and a number of routing words. Each code word stores a code which usually comprises three or six digits used in an associative search by comparison with the corresponding dialed digits. Each code word or group of code words is followed by one or three routing words, each of which designates one or more trunk groups, which may comprise a primary route and a number of alternate routes. Some of the code words include an automatic traffic control digit which directs which one of three routing words is to be used. The value of the traffic digit for each code or group of codes may be modified by a traffic controller by a call from a special station, to thereby designate which one of three predetermined routing plans stored in the respective routing words is to be used. Thus under abnormal traffic conditions caused, for example, by overloads in emergencies, or destruction of facilities, the traffic routing plan may be modified.

16 citations


DOI
08 Dec 1969
TL;DR: CARS as mentioned in this paper is a real-time taxi-like service at a mass transit-like cost, which allows potential passengers to request service from their via telephone, with calls being processed by a central computer facility, periodically executing a routing algorithm which assigns vehicles to passengers and communicates this routing information to the vehicles.
Abstract: CARS is s system designed to provide a taxi-like service at a mass transit-like cost. It allows potential passengers to request service from their via telephone, with calls being processed by a central computer facility. The computer periodically executes a routing algorithm which assigns vehicles to passengers and communicates this routing information to the vehicles. The system is 'real time' in that it will pick up a passenger and shortly after a request will deliver him to his destination within a guaranteed time (with a minimum number of deviations for collecting and delivering other passengers). The key to CARS is the routing algorithm. Since labor and vehicular costs are a major portion of the total system cost, an algorithm is required which can provide an effective dynamic service with a minimum number of vehicles. A variety of such algorithms have been proposed, but these algorithms can not be evaluated in an analytic fashion. Hence, a comprehensive simulation model has been developed to test and compare these routing algorithms. The model facilitates the investigation of relationships between such parameters as number of vehicles and quality of service. This paper describes the methodology of the simulation model and the economic gains (in terms of the need for fewer vehicles) realized through its use. The use of an ARDS storage tube display to produce graphical output from the model is also discussed.

13 citations


Journal ArticleDOI
TL;DR: A simple-but-effective routing tree algorithm is proposed to maintain a dynamic energy-efficient tree structure over all cluster heads, in order to further reduce the energy consumption for those heads to relay data to the sink.
Abstract: This paper proposes a new clustering scheme for wireless sensor networks, which efficiently balances the energy usage inter- and intra-clusters, by using the k - medoids method and the intra-cluster head update policy. Particularly, we propose a simple-but-effective routing tree algorithm to maintain a dynamic energy-efficient tree structure over all cluster heads, in order to further reduce the energy consumption for those heads to relay data to the sink. We also conduct simulations with realistic configurations to evaluate our design in terms of system lifetime, by comparing with LEACH. The experimental results show the efficiency and effectiveness of our work.

7 citations


Journal ArticleDOI
01 Oct 1969
TL;DR: An adaptive routing doctrine is defined, which considers the current delays along links of the network, and a device called a dynamic route selector is described, which takes routing decisions according to the most general doctrine discussed.
Abstract: Three practical constraints on the choice of a deterministic routing doctrine for a connected network are defined, leading to a class of doctrines for which a weighted graph of the network exists so that the specified routes are given uniquely by minimum-cost routes through the graph. A technique for finding such a weighted graph is given. An adaptive routing doctrine is defined, which considers the current delays along links of the network. The implementation of such a doctrine is discussed, and a ‘distributed’ solution described which is efficient, decentralised, and resilient under fault conditions. More general adaptive routing doctrines are defined, considering two parameters associated with each link, where the routing of a message may depend on its history as well as its present position and destination. A device called a dynamic route selector is described, which takes routing decisions according to the most general doctrine discussed. It is faster than a digital computer. Finally a method for first introducing deterministic, and then adaptive, routing on a computer-based network is outlined.

6 citations


Journal ArticleDOI
TL;DR: The problem of finding optimal routings which minimize network losses subject to demand constraints is formulated as a linear program, and extensions to infinite memory and time-varying systems are given.
Abstract: Communication networks with link transit times are modeled by linear graphs with branch time delays and finite branch capacities. Memoryless linear routing strategies as well as linear routing strategies with finite memory are defined. The state reachability problem in both cases is considered, and the sets of reachable demand vectors are exhibited. The problem of finding optimal routings which minimize network losses subject to demand constraints is formulated as a linear program, and extensions to infinite memory and time-varying systems are given.

4 citations


Patent
31 Dec 1969
TL;DR: In this paper, the authors propose a routing device that can conveniently and quickly cause door panels, or the like, to be slotted on a mass production basis for purposes of associating hinges therewith that require slots formed in the panels.
Abstract: Routing devices that can conveniently and quickly cause door panels, or the like, to be slotted on a mass production basis for purposes of associating hinges therewith that require slots formed in the panels. The routing tools thereof are held stationary and the panels are fed toward the routing tools.

1 citations


Journal ArticleDOI
TL;DR: Environment adaptive clustering opportunistic routing protocol (EA-COR) is proposed in this paper to improve the unstable communication quality of harsh environment and simulation results show that in a harsh environment EA-COR performs better than the traditional clustering routing and opportunism routing in the aspects of network throughput, energy efficiency, and packet transmission efficiency.
Abstract: Generally, the radio channel quality of a wireless sensor network (WSN) is unstable in harsh environment. For instance, in maritime search and rescue, the nodes of WSN move dynamically, the topology changes with respect to the time and the communication link changes frequently as well. What is more, the given communication distance of nodes can limit the efficiency of routing. In view of these characteristics of wireless sensor networks in a harsh environment, environment adaptive clustering opportunistic routing protocol (EA-COR) is proposed in this paper to improve the unstable communication quality of harsh environment. EA-COR is based on the idea of clustering which combines with the advantages of opportunistic routing. Simulation results show that in a harsh environment EA-COR performs better than the traditional clustering routing and opportunistic routing in the aspects of network throughput, energy efficiency, and packet transmission efficiency

1 citations