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Ashok Jhunjhunwala
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Ashok Jhunjhunwala
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Ashok Jhunjhunwala
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Jhunjhunwala, Ashok
Jhunjhunwala, A.
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39 results
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- PublicationFibre optics ethernet network for voice and data communication(01-01-1995)
;Sanghi, R. K.; Gonsalves, Timothy A.In this paper, we present a variant of the Ethernet protocol that uses fibre optic media. By the use of periodic frames, the protocol caters to voice and data traffic, adapting to the number of voice calls. This protocol is thus suited for both office automation and industrial applications. We describe in detail how the proposed protocol can be implemented using inexpensive Ethernet VLSI chipsets with a little additional hardware. An extensive simulation study of the protocol shows that the framing imposes minimal additional overhead compared to the standard Ethernet. Under low loads, data delay is low while under heavy loads, voice performance is maintained at the expense of high data delays. - PublicationThe design and flow control of a high speed, integrated, packet switched network(01-01-1992)
;Thilakam, R. KrishnaThis paper proposes a packet switched broadband integrated network, for multi-rate services such as voice and data. A novel design of a high speed packet switch capable of catering to voice and data traffic is described. Some sources of traffic bottle-necks are identified, and methods of clearing the bottle-necks through flow control techniques are discussed. The design and flow control parameters are obtained through simulation, and the results are presented. The performance of the network and the packet switch is evaluated for various traffic characteristics through a second simulation, and the results are briefly presented. © 1992. - PublicationEvaluation of relative merits/demerits of different signalling schemes used on Indian Railways(01-01-2002)
;Goundan, P. R.Presence of Railway stations are essential for train traffic control (to enable crossings and precedence). Movement of trains at stations are controlled by Signals. In busy trunk routes, the running time of trains in station area is comparable to that between stations. Indian Railways use different signalling schemes to enable movement of trains in a safe manner. The signalling schemes play an important role in determining the action of the driver in terms of slowing down of trains and consequently on the throughput of the railway system. This paper examines the different schemes of signalling used currently and in recent past by Indian Railways from the point of view of information that they present to the train driver and the impact that it has on total throughput. The signalling schemes are compared using total signal entropy presented to the driver at each stage. Apart from theoretical computation of signal entropy, results of some experiments conducted on impact of signalling schemes on run time of trains are also presented. - PublicationNew Orientations for Bulk-Acoustic-Wave Devices(01-01-1990)
;Elias, ElizabethIn recent years there has been a considerable interest in bulk-acoustic-wave (BAW) devices. Several new materials/orientations for which strong BAW response is predicted is presented. It is also found that a strong BAW response occurs at a frequency at which the pseudo-surface acoustic wave (PSAW) is expected to occur. © 1990 IEEE - PublicationRe-routing at critical nodes to enhance performance of wavelength reassignment in all-optical WDM networks without wavelength conversion(01-09-2008)
;Rajalakshmi, P.Reassignment of calls to different wavelengths on blocking can be used in WDM networks without wavelength conversion to get almost the same performance as that of WDM networks with wavelength conversion for circuit switched traffic [11]. However, in a few networks, we did find that while the reassignment on blocking does improve the performance of WDM networks without wavelength conversion, the performance falls short of that of wavelength conversion networks. In this paper, we analyze the reasons for this behavior in these networks. On identifying certain critical nodes as a cause of this behavior, we propose a rerouting technique around the critical node. With a small amount of rerouting, this bottleneck can be removed and the performance of WDM networks without wavelength conversion becomes almost equal to that of networks with wavelength conversion, thus making the wavelength conversion (costly) feature, as redundant. In this paper, we also propose a technique to carry out seamless wavelength reassignment so as not to disrupt traffic during the wavelength reassignment process. © 2008 IEEE. - PublicationAnalytical performance computation for all optical networks with wavelength conversion(01-01-2008)
;Rajalakshmi, P.In this paper, we have proposed an analytical model that computes the blocking probability and the channel utilisation for a given load on the optical networks with wavelength conversion at the nodes. The computation has been carried out for fixed routing with uniform traffic distribution (UTD). When any link on a route blocks a call, the dropped call reduces the offered load on all other links invovled in the route. The overall blocking probability of the network is estimated using Erlang fixed point approximation with the reduced load on the links. The expression has been validated by comparing the results with that of simulation for a number of standard networks including 14 node NSFNET, 20 node ARPANET and 20 node INDIANET. We show that the analytical method performs well in the desired range of blocking probabilities and is applicable to any network topology. © 2008 by the IETE. - PublicationDesign tool for symbolic substitution(01-01-1996)
;Parthasarathi, RanjaniA design tool that aids in designing, evaluating, and comparing various implementations of optical symbolic substitution is presented. A hierarchical, modular approach to design similar to that used in digital electronics is supported to facilitate the design of large complex systems. This tool is composed of a schematic capture unit, a simulator unit, and an evaluation unit. Starting with the definition of certain basic or integrated optical elements performing well-defined functions, a schematic capture unit helps to design specific functions. The simulator tool helps to verify the design and the evaluation tool determines its complexity. The usefulness of this design tool is demonstrated with an example design of a simple four-function arithmetic logic unit. © 1996 Society of Photo-Optical Instrumentation Engineers. - PublicationConnecting the next billion: Empowering rural India(01-07-2011)
; Rangarajan, JananiConsiderable efforts over the last decade to provide Internet connectivity in rural India have yielded poor results. However, the success of mobile telephony in rural India in recent years offers hope. © 2006 IEEE. - PublicationDrivers of telecom in india(01-01-2003)After decades of very modest growth, telecom in India has taken off. While liberalisation of telecom sector created the conditions, the key to this take off has been a conscious effort in India to drive down the capital expenditure (CAPEX) of telecom infrastructure which made telecom affordable to large sections of Indian people. This paper discusses the role that Indian and Chinese telecom companies have played towards this reduction of per-line CAPEX and identifies technologies still dominated by the West. Telecom is now set to grow rapidly and India would achieve 200 million connections in less than a decade. However, this optimist situation is still, pretty much confined to urban areas. It is the growth of telecom and Internet infrastructure in rural areas, that have much greater potential. But harnessing of this potential requires special efforts. This paper presents a glimpse of how this could be made possible. © 2003 Taylor & Francis Group, LLC.
- PublicationTheoretical Analysis of Planar Bulk-Acoustic-Wave Response(01-01-1990)
;Elias, ElizabethInterdigital Transducers (IDT’s) on a piezoelectric substrate launch, in addition to surface-acoustic waves (SAW’s), bulk-acoustic-waves (BAW’s) into the medium. Some of these BAW’s reach the output IDT after reflection from the bottom surface. Devices using this phenomenon are known as planar bulk-acoustic-wave devices and have gained considerable importance in recent years due to the fact that they operate at higher frequencies. A detailed theoretical analysis is presented for this device that results in a method for computing the bulk-acoustic-wave response for any orientation of any piezoelectric substrate. The BAW response for several devices for which experimental results are published, is computed using this method. The computed results are found to be in excellent agreement with the experimental ones. The analytical technique is also used to optimize one of these devices to achieve a lower value of insertion loss, by varying the separation between the two interdigital transducers. © 1990, IEEE