Asynchronous Data Services Research Articles

Performance analysis of low earth orbit satellites for power system communication

In this paper the main performances of communication services based on low earth orbit satellites (LEOs) have been analyzed in order to evaluate their suitability for a typical set of power system monitoring functionalities. As an experimental test bed, an intelligent electronic device (IED) for remote monitoring and protection of power components equipped with a bi-directional communication system based on the LEO satellites of the Globalstar ® consortium has been prototyped. Thanks to the adoption of this facility the main parameters characterizing the performance of the satellite TCP/IP services have been evaluated. They comprise in particular the connection time, the degradation of service and data latency for both packet and asynchronous data services. The experimental results obtained show that the application of LEO satellites based communication technologies exhibits a set of intrinsic advantages that could be particularly useful in several fields of power system communication.

Performance of integrated interlan telephony service over an ATM network

The demand for a seamless interconnection between the end subnetworks using ATM technology is steadily arising in the customer premises. A great demand also exists in enterprise networks for obtaining interLAN telephony service integrated with asynchronous data services. We determine the end-to-end performance of internetworked integrated services ATM LANs by using a simulation based approach. We further demonstrate the feasibility of providing interLAN telephony service integrated with asynchronous data services in internetworked ATM LANs. This entails the implementation of a crucial technique, which we have developed in the interworking units so as to segregate the voice data from the asynchronous data. The end subnetworks considered in case of the integrated services homogenous ATM LANs are IEEE 802.5 LANs, whereas the end subnetworks considered in case of integrated services heterogenous ATM LANs are IEEE 802.5 and the standardised 802.9 (isoEthernet) LANs. A significant issue addressed in this case is the internetworking of the packet based IEEE 802.5 LAN to the 802.9 LAN.

HANGMAN Gb/s network

The design and implementation of the Hewlett-Packard active node gigabit-per-second metropolitan area network (HANGMAN) prototype network are discussed. The three main areas addressed are the physical-layer transmission system, the MAC sublayer protocols, and the architecture of the network interface unit. It is shown that low-cost gigabit-per-second transmission systems are practical, particularly in the local area environment where network links are typically limited to a few hundred meters. A MAC protocol that provides a synchronous service as well as the conventional asynchronous data service is described. The node architecture is presented and the way in which a single node can support multiple concurrent physical connections and how this architecture might be used in the future to develop high-performance protocol implementations are also discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>