A set of performance specifications that seem appropriate for real-time computer communication services is proposed. They include various types of delay bounds, throughput bounds, and reliability bounds. Other requirements and desirable properties are described from a client's viewpoint, and the ways in which each requirement is to be translated to make it suitable for lower levels in the protocol hierarchy are examined. Some examples of requirements specification are presented, and possible objections to the approach are discussed. >

Client requirements for real-time communication services

Steganography has proven to be one of the practical ways of securing data. It is a new kind of secret communication used mainly to hide secret data inside other innocent digital mediums. Most of existing steganographic techniques use digital multimedia files as cover mediums to hide secret data. Audio files and signals make appropriate mediums for steganography due to the high data transmission rate and the high level of redundancy. Hiding data in real time communication audio signals is not a simple mission. Steganography requirements as well as real time communication requirements are supposed to be met in order to construct a useful and useful data hiding application. In this paper we will survey the general principles of hiding secret information using audio technology, and provide an overview of current functions and techniques. These techniques will be evaluated across both, steganography and real time communication requirements.

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A survey on steganography techniques in real time audio signals and evaluation

Real-time operating systems generally depend on some form of priority information for making scheduling decisions. Priorities may take the form of small integers or deadline times, for example, and the priorities indicate the preferred order for execution of the jobs. Unfortunately, most systems suffer from some degree of priority inversion where a high priority job must wait for a lower priority job to execute. The authors consider the nature of the nonpreemptible code sections, called critical sections or critical regions, which give rise to this priority inversion in the context of a soft real-time operating system where average response time for different priority classes is the primary performance metric. An analytical model is described which is used to illustrate how critical regions may affect the time-constrained jobs in a multimedia (soft real-time) task set. >

Preemptibility in real-time operating systems

Research in the area of image database management is surveyed. Results with publication dates of 1984-1990 are covered. The impact of technologies such as optical disk storage, digital video, and high-speed local area networks is explored. Programming paradigms, such as object-oriented programming, rule-based systems, and constraint-based methodologies, are discussed. Research in some of the core areas of image database management is surveyed, and an overview is given of some systems. Conclusions based on the survey are given. >

A survey of recent research in image database management

Key references in distributed computer systems 1959–1989

Interest in integrating voice and data on local computer networks has been building in recent years. Subsequently, much research has been devoted to various techniques that are implementable on existing networks using current standards. This exposition discusses the design issues in implementing a document retrieval system on a token ring network.

Bounding delay on a multifarious token ring network

A discussion is presented of the design issues in implementing a document retrieval system on a token-ring network. The presence of real-time traffic, namely, voice, on the same network makes the implementation complicated. The performance requirements of these traffic types are different. Voice creates stream traffic on a network, whereas data traffic is bursty. Voice packets need to be delivered within a limited time interval, whereas the data need emphasizes error-free delivery. A possible solution, using off-the-shelf components and supported by a simulation study, is discussed. >

A. V. Pohm

Papers

Bounding delay on a multifarious token ring network

Bounding delay on a token ring network with voice, data and facsimile applications: a simulation study