/ V. B. Marakhovsky / Professor
/ Zi Xue Cheng / Assistant Professor
/ Kshirasagar Naik / Assistant Professor
Computer Networks Laboratory is working in four directions within Research Projects and Top-Down Education Course-ware Development Projects:
Refereed Journal Papers
Local processes in MPCS can be coordinated by asynchronous system of global synchronization via handshake using current sensors for detection of the transient processes completion. The known current sensors are considered, the best one is analyzed and its shortcomings are revealed. Current sensor with wide range of the measured current is suggested. The principles of control in circuits with current sensors are developed. Self-timed data exchange between local processes of the system is discussed. Transmission/reception circuits with single-wire bit handshake are demonstrated. Their transmission rate is no worse than that of double-wire circuits. They allow one to transmit combinations of $n$-bit code by $n+2$ communication lines.
This paper makes two contributions toward computing Unique Input/Output (UIO) sequences in finite state machines. Our first contribution is to compute all UIO sequences of minimal lengths in a finite state machine. Our second contribution is to present an efficient algorithm to compute a UIO sequence for each state, if it exists.
In this paper, we study the effects of a service provider on conformance testing of communication protocols. From the viewpoint of conformance testing, the three main characteristics of a service provider are dynamic round trip delay, message buffering, and lossy transmission. We show that if proper care is not taken in test architectures and test cases, the dynamic attributes of a service provider may render correct test cases useless. We propose new features of test architectures to improve their reliabilities.
We design a protocol to efficiently deliver multicast messages to mobile computers. The main concern in the design of such a protocol is to ensure that each message is delivered exactly once to each mobile host in the multicast group. However, the requirements of avoiding to deliver a message more than once, and of a host not missing a message are not easy to satisfy efficiently in a mobile environment. To satisfy these requirements, an earlier work had to actually broadcast a multicast message. The novelty of our approach is that we satisfy the multicast requirements without broadcasting a message, which is central to the efficiency of our algorithm.
In this paper, we proposed A Support Environment for ADT Specification based on Reuse of Similar ADT.
In this paper, we proposed A New Approach to ADT Specification Support Based on Reuse of Similar ADT by the Application of Case-Base Reasoning.
The problem of global synchronization for asynchronous cellular automata arrays is considered. Global synchronization of an asynchronous system is treated as a homomorphic mapping of its behavior in logical time onto the behavior of the corresponding synchronous prototype system that functions in physical time. Here we developed the idea of decomposing an asynchronous array to the automata stratum (close to the synchronous prototype array with cells modified to organize timing handshake) and synchronization stratum which functions as a distributed asynchronous clock. We considered various disciplines of prototype timing and the corresponding synchro-stratum implementations.
Asynchronous design technique has an approach of using padding delays to produce signals of transient process completion. In order to increase the efficiency of this approach, we suggest to use data-controlled incorporated delays in the cases when the variations of transient process durations are determined by the sets of input signal values. The control over the value of an incorporated delay is illustrated by an example of asynchronous adder design. The results of PSPICE simulation confirm the efficiency of this approach.
We discuss the problem of designing asynchronous control devices for discrete event coordination specified by a Petri net model. The design is based on the compilation of standard circuit modules corresponding to PN fragments into a net modeling PN behavior and on the semantic interpretation of the modeling circuit. The impossibility of asynchronous implementation of the indivisible operation of marking change at the circuit level leads to the necessity of modeling PN with modified rules of marking change. Modifications of the known modules, a number of new module types, the rules of the module connections, and the procedures of minimization are given that considerably improve the quality of the obtained solutions in terms of both speed and area. The design ``reefs'' are fixed. The minimization procedures are usually associated with a change of marking change rules producing the problems of providing the equivalence of the initial and modified PNs.
An approach to design asynchronous systems that coordinate concurrent discrete events of an arbitrary physical nature is discussed. To build asynchronous control circuits that coordinate process interaction, the method of direct translation of interact specifications using Petri nets is being developed. Modifications of the known modules and a number of new modules modeling fragments of Petri nets are given. These modules considerably improve the quality of the obtained solutions. The design ``reefs'' are fixed. The minimization procedures are associated with a change of marking change rules.
The problem of global synchronization in massively parallel systems is discussed for the level of models represented by asynchronous cellular automata arrays. Synchronization is called global if a given asynchronous automata array functions in logical time so that its behavior can be homomorphously mapped to the behavior of the prototype synchronous system in physical time. Our approach is decomposing the asynchronous array to synchro-stratum which acts as a distributed asynchronous clock and automata stratum whose automata have a construction similar to that of the synchronous prototype array automata. For various disciplines of prototype synchronization, the corresponding variants of synchro-stratum implementation for the asynchronous analogue are discussed.
We model the cognitive behavior of agents in a multi-agent system.
In this paper, we proposed A Distributed Algorithm for Implementation of First-Order Multiparty Interactions.
In this paper, we proposed Efficient Distributed Ranking and Sorting Schemes for a Coterie.
In this paper, we proposed A Distributed Algorithm for Dice Tossing.
The problem of assigning students to professors' projects is studied in the field of OR (Operation Researches), as an allocation problem. However, in many cases solutions based on liner programming can't be used practically, since students' and professors' preferences and suitability are not considered sufficiently. In this paper, we propose a new solution by using a concept aptitude based on decision making principle in social psychology.
Scheduling meetings is one of main topics in groupware. Existing methods for meeting scheduling consider mainly paticipants' preferences for meeting time. However, they didn't consider to schedule required meetings to be held as many as possible concurrently to increase the productivity of an organization. In this paper, we propose a new method for scheduling meetings, called Continuous Concession method which arranges meetings to be held concurrently as many as possible, with the participants' preferences for time and meetings being considered also.
Resource allocation is a fundamental problem in distributed systems. Many deadlock-free and starvation-free distributed algorithms have been developed for the resource allocation. However, with the progress of computer networks, a various of group activities over computer network by using groupware become possible and required. When many groups are using the same network resources, competition for resources may happen among group. Even though the deadlock and starvation never happen, the GROUP DEADLOCK and GROUP STARVATION may happen. The new type of problems are very difficult solved by existing algorithms. In this paper, we propose a new algorithm for resolving the competition among groups.
We proposed a design methods for Scheduling Meetings.
Embedded systems often have a limited scope for human intervention in their operation and maintenance. A careful distribution of fault-tolerance responsibilities between hardware and software components is therefor a critical factor of dependability in such systems. A general trend in design of embedded systems is an increasing role oh hardware in providing their main functionality. Classical hardware designs for dependability use clock and are therefor dependent on the clock distribution logic, which itself becomes more complex. Asynchronous circuits are posed as a promising alternative especially for embedded systems, mainly due to their potential for lower power consumption and lower electro-magnetic interference. Additionally, asynchronous designs offer inherent self-checking properties due to their ability to acknowledge the completion of transient in subcomponents. This presentation focuses on a number of techniques for self-checking and self-recovery available in self-timed systems and points to some new challenges.