Design Of Communication Protocols Research Articles

Modeling of communication protocols by using petri nets

Abstract The design and verification of communication protocols is one of the challenging problems. One approach to solve the problem is to use Petri Nets as an analytical tool. In this approach a protocol is modeled as a Petri Net (a graphical representation) and is analyzed by using the same techniques as for Petri Nets. The application of Petri Nets in the design, analysis and verification of communication protocols, has several advantages. First of all the overall behaviour of a protocol is often easier to understand due to the precise nature of the representation scheme. Secondly, Petri Net theory and its analysis techniques can be easily applied. Finally, since Petri Nets can be synthesized by using bottom-up or top-down approaches, it is possible to derive the overall model via a combination of subsystems whose behaviour is already known or can be easily verified. In this paper two major analysis techniques, namely, reachability tree and matrix analysis are explored. Since communication protocols are usually too complex to be analyzed, therefore, this paper describes a simulation program that simulates the dynamic behaviour of Petri Nets. The program points out all deadlock states, if any, and checks for boundedness of protocols.

Attenuation of Communication Signals on Residential and Commercial Intrabuilding Power-Distribution Circuits

The use of electric-power-distribution circuits for intrabuilding communications is ol continued and growing interest. The purpose of this paper is to present intrabuilding signal attenuation measurements taken from five different buildings. The measurements cover the range 20-240 kHz and include transmissions across power phases. The measurements complement earlier measurements by others of power-line impedance and noise. Impedance, attenuation, and noise characterize any communication channel and are needed for design of communication signaling formats, error-control codes, and communication protocols. Except over short distances, attenuation normally exceeds 20 dB, and can be much higher. The attenuation which occurs when the transmitter and receiver use different power-line phases is not always larger than when both are on the same phase. Narrow-band frequency-selective fades can occur and change as network loading changes, and can also exhibit periodic time dependence. Loading, which is time varying, greatly affects signal attenuation between network nodes. The results clearly indicate that power-line signal attenuation is highly variable and unpredictable, is variable with communication signal frequency, and is not easily modeled mathematically. The implications of our results for intrabuilding communications on power-distribution circuits are discussed.

Automated testing of protocol specifications and their implementations

A highly automated approach is proposed for validating the consistency of distinct representations of an identical software functionality. This approach is based on checking whether the observable behaviors presented by software functionality representations given in different levels of abstraction are consistent with one another. These representations are encoded in a relatively mechanical way as procedures in sequential PROLOG, a very high level language. The approach is extremely flexible, straight-forward to use, and particularly appropriate to layered protocol architectures. As well, the approach leads to more reliable and less tedious, less error-prone test harness construction and maintenance. A number of variations and extensions of the approach are given. The use of this approach is illustrated in the context of communication protocols design and evaluation.

A Set of Tools for Designing and Evaluating Communication Protocols in Industrial Computer Networks

The problems of communication protocols evaluation and design are considered in the context of designing a distributed computer control system's software. Quirk's model is used for software requirement specification. From the same model are obtainable demands for communication network properties.Some application oriented network characteristics are derived, such as a message transition time, an overload toleration time, which are based on a notion of effective information transfer rate. The latter depends on a communication protocol and on physical properties of the communication line.The report ends with comparative data, computed using the formulae derived in this paper, of the two operational industrial networks applied to a model problem.

Verification and evaluation of communication protocols

Transmission errors, failures and variable transit delays are important characteristics of computer communication networks. Hence, designing a reliable communication protocol for such an uncertain environment is a challenging task. A case study is reported which shows how helpful heuristic techniques can be in protocol verification and a theorem is given regarding synchronization of communicating entities. Another facet of the communication protocol design issue is efficiency. Heuristic techniques have been used also to evaluate performances of various flow control mechanisms intended for internode protocols and transport protocols as well as performances as seen by users of computer networks Finally data regarding tradeoff choices are given.

Message communication protocol and operating system design for the Distributed Loop Computer Network (DLCN)

The Distributed Loop Computer Network (DLCN) is envisioned as a powerful, unified distributed computing system which interconnects midi/mini/micro-computers, terminals and other peripherals through careful integration of hardware, software and a loop communication network. Research concerning DLCN has concentrated on the loop communication network, message protocol and distributed network operating system. For the loop communication network, previous papers [2,3] reported a novel message transmission mechanism, its hardware implementation, and its superior performance verified by GPSS simulation. This paper presents an overview of the design requirements and implementation techniques for DLCN's message protocol and network operating system. Firstly, a bit-oriented distributed message communication protocol (DLMCP) which handles four message types under one common format is proposed. Besides user information transfer, this protocol supports automatic hardware-generated message acknowledgment, error detection and recovery, and network control and distributed operating system functions, Secondly, the network operating system (DLOS) is described which provides facilities for interprocess communication by process name, global process control and calling of remote programs, generalized data transfer, alterable multi-linked process control structures, distributed resource management, and logical I/O transmission in a distributed file system.

A Methodology for the Design and Implementation of Communication Protocols

This paper presents a coherent method which permits the specification, check out, and implementation of communication protocols. Although this work is mainly directed towards telephone signaling in a programmable environment, the philosophy and most of the tools can be effectively used to handle the most general situations in which two entities interact by any kind of protocol. Since the proposed approach reduces the possibility of errors and inconsistencies, minimizes the programming needed, and improves the documentation and understandability, we believe that this methodology will facilitate the installation or modification of complex trunk protocols and other communication protocols.

Communication protocols and error recovery procedures

The design of multiple computer systems and computer networks poses some interesting new problems and shows some older problems in the light of a new context. We are interested in the problems which are related to the design of communication protocols and error recovery procedures. In the design of computer systems, error recovery procedures have often not received very much attention, although they are essential for the reliable operation of most systems. In the case of multiple computer systems, appropriate error recovery procedures can be used to obtain a very much increased availability of the system services. This is also an advantage of computer networks. Whereas single computer systems can sometimes function to a certain extent without elaborate error recovery procedures, data communication protocols, on the other hand, normally have to contain explicit error recovery procedures, since the underlying communication line is normally not very reliable. Therefore, approaches that have been used for the design of protocols in computer networks could also be useful in the design of local multiple computer systems for obtaining higher reliability and availability.