Kishore Angrishi

Analysis of a Real-Time Network Using Statistical Network Calculus with Approximate Invariance of Effective Bandwidth

The modern industrial network traffic consists of an increasing amount of soft real-time flows, which can tolerate very small delay and losses. Allowing probabilistic Quality of Service (QoS) violation for these flows can greatly help to improve resource utilization. However, the improvement depends on the statistical properties of competing independent flows. The notion of effective bandwidth, summarizes the statistical properties and QoS requirements of a flow. This paper suggests the usage of effective bandwidth to describe the arrival process of the flow along its path in a. network within the framework of the statistical network calculus. Further, we improve the existing formal relationship between effective envelope and effective bandwidth to achieve a better bound for the arrival process. This new approach enables efficient utilization of statistical multiplexing of independent flows both at the ingress of the network and along the path of the flow.

A Node Operating Point Approach for Stochastic Analysis with Network Calculus

The operating point of a node is an interesting concept from large deviations theory which defines the asymptotic buffer occupancy distribution at the node. The effective band-width function evolved out of large deviations theory, establishes the crucial connection between the node operating point and the theory of statistical network calculus. This paper uses the concepts of effective bandwidth and effective capacity to describe independent stochastic arrival and service processes, respectively, and to identify node operating point to perform stochastic analysis with network calculus. The two main advantages of the approach used in this paper are: (i) the use of operating point to perform stochastic analysis provides insight into the queue dynamics, and (ii) the use of effective bandwidth and effective capacity functions within the framework of statistical network calculus allows efficient evaluation of performance bounds.

An application of a formal approach for distribution of real-time control

A system which provides a set of control functions on time is referred as a real-time control system (RTCS). In a traditional RTCS, a set of tasks running in a central controller provide the required system control. The recent technological advances have made it possible to embed controllers with sufficient computing power directly in the end control devices. These devices also have a communication interface by means of which they can communicate with the other devices via a broadcast bus. These devices are referred to as intelligent nodes. A network of such intelligent nodes can be used to perform the same control functions as that of a centralized RTCS in a distributed manner. This paper discusses an application of a formal approach to distribute the control of a centralized RTCS over a set of intelligent nodes with an example.

On the Observance of Approximate Invariance of Effective Bandwidth with Finite Number of Sources

The effective bandwidth is a descriptor in the context of stochastic models for statistical sharing of resources. One of the most interesting properties of effective bandwidth is that it does not change when passing a network node under many sources limiting regime (infinitely many sources). This is referred as the “invariance property” of effective bandwidth. Numerical simulations have suggested that in some cases, the “invariance property” of effective bandwidths holds already for a surprisingly small number of competing flows even in the presence of aggressive TCP traffic. The real question, though, is: how many input processes are needed for reasonable convergence over the scale of interest? This work addresses this question using recent results from the large deviations theory under many sources limiting regime and the theory of statistical network calculus. We also show that as the number of arrival flows increases, the bound on the departure process’ effective bandwidth converges exponentially fast to that of the effective bandwidth of the arrival. The advantage of identifying the minimum number of independent multiplexing flows at each network node to observe approximate invariance of effective bandwidth is that the task of network resources dimensioning can be greatly simplified.

An Approach for Interoperable Service Mediation in Diverse Telecommunication Networks

Mobile telecommunication networks consist of several co-existing, independent domains. Communication protocols in these diverse domains can be broadly classified into IP-based and SS7-based protocols. Modern IP-based network nodes already rely on service-oriented architectures (SOA) while SS7 based system is based on switching offices and a specialised service control. Service-oriented mediation between those networks is a challenging task. This paper addresses interoperable service-mediation by combining service descriptions, protocols and the integration of application data. The service mediation approach aims to combine performance-oriented interoperability with SOA concepts