Ade Chaky

In this paper, a high efficiency C-band GaN HEMT high power amplifier with internal harmonic manipulation circuits is presented. We employed a new circuit topology for simultaneous high efficiency matching at both fundamental and 2nd-harmonic frequencies. The developed GaN HEMT amplifier has achieved over 57% drain efficiency (50% power-added-efficiency) with 100 W output power at C-band. This is the state-of-the-art efficiency of GaN HEMT high power amplifier at C-band to the best of our knowledge.

Traffic in IP networks has increased and services have diversified over the last few years. IP networks need to have scalability and high-quality data transmissions and they must be able to incorporate new functions. For good processing performance and ease of adding functions to the transport stratum on a next-generation network (NGN), we have proposed a functionally distributed transport networking architecture that separates the control-plane processing part (control element, CE) from the forwarding plane processing part (forwarding element, FE) of the router. In this architecture, the CE is mounted on a general-purpose server platform, and one path-control process in the CE consolidates and processes the path computations and the path settings for two or more routers. The functions and performance of the CE are easily upgraded. Moreover, a particular CE computes the path for an entire network by using the single network-integration path-control method that treats each sub-network as one router. This leads to efficient operation of a large-scale network. In this paper, we argue that the issues of our architecture could be bottleneck factors for the path computational performance in a large-scale network and we predict the influence of these factors by using a simulation environment.

In this paper, an X-band internally-matched GaN HEMT high efficiency amplifier is presented, which is equipped with second harmonic control circuits to enhance the efficiency of the GaN HEMT. The internal matching circuit was designed so that the 2nd harmonics are tuned to obtain maximum power added efficiency (PAE). PAE of 57% was successfully obtained with 12.5W output power at X-band. This is the state-of-the-art high efficiency for X-band GaN HEMT amplifiers with more than 10W output power to the best of our knowledge.

Mobile Ad-hoc Networks (MANETs) have gained a lot of importance in the recent years due to their flexible ways of operation, where mobile nodes form the network to communicate with each other, without the aid of any fixed infrastructure. Routing in MANETs is a challenging task mostly for its rapidly changing topology. Several routing protocols have already been proposed and

We developed a heterostructure FET (HFET) with a high output power and a high power-added efficiency (PAE) at Ku-band. 8 W and 11.2 W output powers were obtained with power-added efficiencies of 48% and 41% and linear gains of 9 dB and 8.6 dB at 12 GHz, respectively. This is the highest power and efficiency ever reported which is achieved

The dynamic nature of MANETs makes the task of routing between source and destination nodes extremely difficult. In this paper a new efficient routing algorithm for mobile ad hoc networks is presented, along with a brief review of the state of the art scenario of routing topologies for MANETs. The new algorithm takes into consideration the mobility factor during routing.

Ad hoc mobile networks (MANET) vary greatly depending on their application area and environment in which they work. We have presented a brief review of the state of the art security scenario for MANETs and also pinpointed some of the loopholes of the existing intrusion detection systems (IDS) before we proposed a new collaborative algorithm called IDSX. The proposed IDSX offers an extended architecture and is compatible with heterogeneous IDS already deployed in the participating nodes. While maintaining a high level of intrusion detection, the proposed solution virtually eliminates the problem of phantom intrusion detection to a great extent by aggregating the locally generated alerts to keep or discard a suspected intruder in a two step process.

A novel compact phase shifter switching three phase states has been demonstrated. The circuit is constructed by adding switching FETs to a conventional single-stage two-phase-state phase shifter. A conventional three-stage, two-phase-state phase shifter can be replaced by the two-stage, three-phase-state device. The total chip size of the newly developed phase shifter is 2/3 that of the conventional one. The authors report on the design of and experimental results for reflection- and loaded-line-type phase shifter (MMICs) (monolithic microwave integrated circuits).>

... Soma Saha Tripura University Suryamaninagar, Tripura somasaha84@gmail.com Rituparna Chaki WB University of Technology Calcutta 700064, INDIA rituchaki@gmail.com Nabendu Chaki University of Calcutta Calcutta 700009, INDIA nabendu@ieee.org Abstract ...

In multi-hop wireless systems, the need for cooperation among nodes to relay each other's packets exposes them to a wide range of security attacks. A particularly devastating attack is the wormhole attack, where a malicious node records control traffic at one location and tunnels it to another compromised node, possibly far away, which replays it locally. Routing security in ad hoc networks is often equated with strong and feasible node authentication and lightweight cryptography. Unfortunately, the wormhole attack can hardly be defeated by crypto graphical measures, as wormhole attackers do not create separate packets. They simply replay packets already existing on the network, which pass the cryptographic checks. Existing works on wormhole detection have often focused on detection using specialized hardware, such as directional antennas, etc. In this paper, we present a cluster based counter-measure for the wormhole attack, that alleviates these drawbacks and efficiently mitigates the wormhole attack in MANET. Simulation results on MATLab exhibit the effectiveness of the proposed algorithm in detecting wormhole attacks.

... Poly Sen Asansol Engineering College Asansol, India poly_sil@rediffmail.com Nabendu Chaki University of Calcutta Calcutta 700009, India nabendu@ieee.org Rituparna Chaki WB University of Technology Calcutta 700064, India rituchaki@gmail.com Abstract ...

... The dependency of AODV on sequence number makes it vulnerable to black hole ... Hoc NetworNs under Noise and Imperfect monitoring",Um Theses and Dissertations, Digital Repository at ... and Michael R. Lyu, Roland T. Chin, IAn Authentication service Against Dishonest Users ...

Mobile ad hoc networks consist of wireless hosts that communicate with each other without the support of fixed infrastructure. In case of large network, a flat structure may not be the most efficient organization for routing. For this purpose many clustering schemes have been proposed that organize the MANET into a hierarchy, with a view to improve the efficiency of routing. In this paper, we have presented a brief review of the state of the art scenario of routing topologies for mobile ad hoc networks and try to present a scheme that leads to cluster formation which efficiently uses the resources of the MANET. The proposed Cluster Based Mobility Considered Routing Protocol obtains efficient communications among MANET and achieves scalability in large networks by using the clustering technique. The new algorithm takes into consideration the mobility factor during routing and as well as computational overhead is also diminished.

Abstract An ad-hoc network is a self-supporting collection of mobile nodes that happen to exist within a close proximity in an interval of time. In this paper, a reactive routing protocol has been proposed that computes the shortest path in between any source-destination pair on ...

An Intrusion Detection System (IDS) detects malicious and selfish nodes in a network. Ad hoc networks are often secured by using either intrusion detection or by secure routing. Designing efficient IDS for wireless ad-hoc networks that would not affect the performance of the network significantly is indeed a challenging task. Arguably, the most common thing in a review paper in the domain of wireless networks is to compare the performances of different solutions using simulation results. However, variance in multiple configuration aspects including that due to different underlying routing protocols, makes the task of simulation based comparative evaluation of IDS solutions somewhat unrealistic. In stead, the authors have followed an analytic approach to identify the gaps in the existing IDS solutions for MANETs and wireless mesh networks. The paper aims to ease the job of a new researcher by exposing him to the state of the art research issues on IDS. Nearly 80% of the works cited in this paper are published with in last 3 to 4 years.

The challenges of mobile ad hoc network are to maintain quality of services and performance. Many routing protocols like AODV discover routes whenever required by the source node and the benefit in doing so is that no prior knowledge of the topology is required. The AODV routing protocol is commonly and effectively used for mobile, ad-hoc nodes. So far, many maintenance strategies have been proposed on AODV to provide better QoS services performances. Some has used the radio propagation characteristics of mobile nodes in ad hoc network during route maintenance. Some modification has been done on computation of delay parameter. The other modification was on multi route selection during route discovery considering only delay as QoS parameter. This paper aims towards proposing a new route maintenance strategy with multiple options that will lead to better performance during link failure on a route. During route discovery and route reply procedure two different QoS parameters considered here are delay and bandwidth. The routes should be selected during route discovery process. The route maintenance strategy may be applied to both the routes independently and simultaneously by the internal nodes where the link failure has occurred.

In this paper, authors have proposed a VAS for personal video recorder (PVR) enabled iSTB. The proposed solution can recognize the regions in the frames where the recipe and ingredients are shown and can save them in image/text format for further use. We have used a hybrid approach where the text regions are localized using the compress domain features of the streaming video in real time and then some pixel domain processing is performed on that reduced region of interest to recognize the text. The novelty of the proposed approach lies in using the compressed domain features of H.264 video in text localization and applying some pixel domain post processing on the ROI to perform the entire recognition process in real time. The system is tested over a video upto CIF resolution and can recognize the text successfully with an accuracy of nearly 80%.

In this paper, a GaN HEMT high efficiency amplifier and a module composed of a GaN HEMT amplifier are presented, which operates at 5.8GHz. GaN HEMT is considered to be suitable for harmonic tuned high efficiency amplifiers compared with existing GaAs FET amplifiers, due to its high voltage operation and high impedance natures. A high efficiency GaN HEMT amplifier is designed and evaluated, which is equipped with fundamental, second and third harmonic matching circuits in a hermetically sealed metal package. As a result, a high power added efficiency of 70.5% was obtained with associated output power of 7.3W. As the GaN HEMT employed in this work has already passed space qualify tests (SQT), this amplifier will be an important component to realize space solar power systems. Moreover, the module composed of this high efficiency GaN HEMT amplifier supplies the condition for the maximum performance of this amplifier. As a result, a high power added efficiency of 43+/-1% was obtained as a module.

Abstract -- In this paper, we present a new reactive routing protocol that we call Optimal Reactive Routing Protocol (ORRP). The proposed protocol does not require global periodic advertisement of routing messages like the proactive approaches. At the same time, ORRP guarantees ...

In this paper, an internally-matched GaN HEMT high efficiency amplifier for Space Solar Power Stations/System (SSPS) is presented. The internal matching circuit was designed so that 2nd and 3rd harmonics are tuned to obtain maximum power added efficiency (PAE). PAE of 70% was successfully obtained with 7W output power at 5.8GHz. All matching circuit is in a hermetically sealed package and no external matching component is necessary. It will enable to shrink volume and mass of modules loaded onto SSPS satellites.

Mobile Ad-hoc Network (MANET) is the self organizing collection of mobile nodes. The communication in MANET is done via a wireless media. Ad hoc wireless networks have massive commercial and military potential because of their mobility support. Due to demanding real time multimedia applications, Quality of Services (QoS) support in such infrastructure less networks have become essential. QoS routing in mobile Ad-Hoc networks is challenging due to rapid change in network topology. Consequently, the available state information for routing is inherently imprecise. QoS routing may suffer badly due to several factors including radio interference on available bandwidth, and inefficient flooding of information to the adjacent nodes. As a result the performance of the network degrades substantially. This paper aims at the solution for energy efficient QoS routing by best utilization of network resources such as energy and bandwidth. A comparative study shows that despite the overhead due to QoS management, this solution performs better than classical OLSR protocol in terms of QoS and efficient utilization of energy.

This paper aims towards a critical retrospection of some of the most bugging limitations of cluster formation and cluster head selection. Based on this, a new Weighted Adaptive Clustering Algorithm (WACA) has been proposed. The proposed methodology is aimed at reducing the transmission overhead, total required time and increasing the stability of the formed cluster. WACA can dynamically adapt itself to the frequently changing topology of ad-hoc network.

ABSTRACT In this paper a comprehensive review on some of the very recent works on Quality of Service issues in MANET has been presented. Although MANET has been initially proposed for disaster recovery and military communication, in today's world it has reached the ...

In case of wireless networks with infrastructure there is a base station which is reachable through all mobile nodes. Ad-hoc network defers in this point where destination nodes might be unreachable from source nodes. The Mobile Ad-Hoc Network are prone to packet loss and route congestion due to their dynamic nature. The lack of centralized infrastructure adds up to these problems. In this respect cluster based routing mechanism is necessary for dealing with such problems. This paper emphasizes the shortest path finding between the source and destination in cluster based adhoc network for reducing packet delay and energy consumption. The paper also includes a performance comparison of this logic with existing SDSSR algorithm.

Vehicular Ad hoc network is a special case of Mobile Ad hoc networks, with high nodes mobility specification and a large energy resource which could extend coverage and system lifetime. Providing reliable and efficient routing in presence of relative movement motivates the introduction of movement awareness to improve performance of existing position-based routing schemes in Vehicular Ad hoc networks. Dramatic increase in the number of vehicles equipped with computing technologies and wireless communication devices has created new application scenarios. In order to meet performance goals in VANET, several routing protocols have been formulated. Each of the existing routing protocols comes with their pros and cons. In our work we propose a new routing protocol, A Speedy Routing Protocol for Vehicular Ad hoc Network. In this routing protocol we try to reduce overhead of maintaining routing data and traverse preferred distance through shortest path.