Linear analysis of a terahertz staggered double-grating arrays waveguide Cerenkov traveling wave amplifier

Based on a sheet electron beam propagating through the tunnel of a staggered double-grating arrays waveguide (SDGAW) slow-wave structure (SWS), a three dimensional linear theory for describing beam-wave interaction is presented, in which the higher order terms inside the groove were retained.

With the optimized parameters, a 1THz SDGAW Cerenkov traveling wave amplifier (CTWA) may obtain a moderate net gain larger than 10dB/cm in 0.92THz to 1.145THz considering the serious Ohmic losses in THz frequency range.

Independent transient plane design for protection in OpenFlow-based networks

Network protection against link failure is required to allow packets to reach the destination with minimal packet loss when a failure occurs. When a link fails, traffic that attempts to use the failed link is interrupted. Typically, routers in the network discover the failure and find a new route to bypass the failed link. Alternatively, well-known segment protection schemes can also be used to speed up the link recovery time by rerouting packets locally through precalculated protection paths. However, several backup paths have to be prepared for each primary path, making path configuration rather complex and poorly scalable.

This paper proposes a design for fast rerouting in an OpenFlow-based network. This new design reduces the number of flow entries and the number of configuration messages needed for network rerouting, which in turn reduces the memory size needed in each switch and the CPU load at the controller. We show empirically and using simulations that our design can reduce the number of flow entries and configuration messages needed by about 60% and 75%, respectively, when compared with an existing OpenFlow-based segment protection design. Furthermore, we implement the proposed design on a pan-European network and show that our design can recover from a link failure in as little as 25 ms.

Low power and high performance MOSFET

To analysis leakage current and delay for Double Gate MOSFET with Single gate MOSFET at 45nm in CMOS Technology by using the Cadence Virtuoso simulation tool. When compared to single gate MOSFET, the leakage current and delay are observed to be reduced in double gate MOSFET. The drive current remains the same for both single and double gate MOSFET based on Vgs but the short channel characteristics of double gate MOSFET gets improved.

Double gate MOSFET is mostly recommended for low power and high performance application. When compared to bulk Si single gate device, the total power utilization of inverter, static, dynamic circuit and latch by using double gate demonstrates that leakage current and delay reduced by a factor of over 10X.

System analysis for optimizing various parameters to mitigate the effects of satellite vibration on inter-satellite optical wireless communication

Inter-satellite links are necessary between satellites in orbits around the earth for data transmission between satellites and also for efficient data relay from one satellite to other and then to ground stations. Inter-satellite Optical Wireless Communication deals with the use of wireless optical communication using lasers instead of conventional radio and microwave systems. Optical communication using lasers provide many advantages over conventional radio frequency systems.

A major problem existing in this wireless optical communication for inter-satellite links is the effects of satellite vibration, which results in serious pointing errors that degrade the performance. Performance of this system also depends on various parameters like transmitted power, data rate and antenna aperture which are analyzed using OptiSystem simulation software. This paper suggests ways to tackle effects of satellite vibration by optimizing the parameters of system design. The results of this study could be used further to design a feedback loop to correct effects of satellite vibrations in the system.

Revisiting TCP Outcast Problem Using DCTCP in Data Center Networks

Data Center Networks (DCNs) today are used to compute and store the data of multiple users because of low cost, flexibility and availability. In this multi-tenant cloud environment, resources are shared among different users. Suppose two users fetch data at same time from the same DCNs, one fetches small amount of data (like web search) while another user fetches larger amount of data (like software update). If these large set of flows and small set of flows arrive at two different input ports of a switch and compete for same output port, then large flow packets get the buffer while small flow packets are dropped consecutively.

This issue occurs due to drop tail implementation of queue in switches and as one set of flows is outcast by other, the problem is known as TCP Outcast. While a few studies have already explored the TCP Outcast problem, this paper aims to revisit this problem by using DCTCP in DCNs. The experiments carried out using Mininet show that DCTCP solves the problem of TCP Outcast by ensuring fairness for all types of flows.

Secure communication system for wearable devices wireless intra body communication

This paper explains how intra-body communication can be used to establish a secure communicationchannel for wearable devices. Intra-body communication transfers data using the human body as its conductor. This paper describes a secure communication system that supports multiple wearable slave devices.

Our prototype, wearable on the wrist, has an integrated processor to control the intra-bodycommunication module. Instead of using radio transmission, the module uses the human body, thus maximizing the security of transmitted signals.

Testing analytics on software variability

Software testing is a tool-driven process. However, there are many situations in which different hardware/software components are tightly integrated. Thus system integration testing has to be manually executed to evaluate the system’s compliance with its specified requirements and performance. There could be many combinations of changes as different versions of hardware and software components could be upgraded and/or substituted. Occasionally, some software components could even be replaced by clones. The whole system after each component change demands to be re-tested to ensure proper system behavior.

For better utilization of resources, there is a need to prioritize the past test cases to test the newly integrated systems. We propose a way to facilitate the use of historical testing records of the previous systems so that a testcase portfolio can be developed, which intends to maximize testing resources for the same integrated product family. As the proposed framework does not consider much of internal software complexity, the implementation costs are relatively low.

Adaptive Lookup Protocol for Two-Tier VANET/P2P Information Retrieval Services

Intelligent transportation system (ITS) services have attracted significant attention in recent years. To support ITS services, architecture is required to retrieve information and data from moving vehicles and roadside facilities in an efficient manner. A two-tier system that integrates low-tier vehicular ad hoc networks (VANETs) and a high-tier infrastructure-based peer-to-peer (P2P) overlay, which can achieve a high lookup success rate and low lookup latency for information retrieval, has been developed. However, conventional information lookups in the two-tier VANET/P2P system may introduce extra lookup messages and latencies because the lookup queries are simultaneously performed over the VANET/P2P networks.

This paper proposes an adaptive lookup protocol for the two-tier VANET/P2P system to improve the efficiency of information retrieval. The proposed protocol uses a Bloom filter, which is a space-efficient data structure, to collect reachability information of road segments; therefore, adaptive routing of queries between low- and high-tier networks according to reachability probability can be employed. Simulations based on the SUMO traffic simulator and QualNet network simulator demonstrate that compared with the conventional two-tier lookup mechanism, the adaptive lookup protocol can reduce the lookup latency by 12%, reduce the P2P lookup overhead by 20%-33%, and achieve a high success rate in information lookups.

Smartphone Security: An overview of emerging threats.

The mobile threat landscape has undergone rapid growth as smartphones have increased in popularity. The first generation of mobile threats saw attackers relying on various scams delivered through SMS.

As the technology progressed and Web browsers, e-mail clients, and custom applications became standard on smartphones, attackers started exploiting new possibilities beyond traditional e-mail spam and phishing attacks. The landscape continues to evolve with mobile bitcoin miners, botnets, and ransomware.

Detection of node-misbehavior using overhearing and autonomous agents in wireless Ad-Hoc networks

In Wireless Ad-hoc Networks, nodes co-operate among themselves to forward data packets from a source node to a destination node. Nodes may participate in route discovery or route maintenance process but refuse to forward packets due to presence of faulty hardware or software or to save their resources, such as, battery power and bandwidth. Detection and isolation of misbehavior nodes are important issues to improve the quality of communication service and to save resources of well behaving wireless nodes. In this work, firstly, a neighbor Overhearing based Misbehavior Detection(OMD) scheme is proposed. In OMD, each node overhears the transmissions of its neighbors and calculates packet forwarding ratio of its own as well as its neighbors.

Source node uses the calculated information to identify a misbehaving node. Secondly, an Autonomous Agent based Misbehavior Detection( AAMD) technique is proposed. In AAMD, past behavior of nodes in the networkis used as a metric to calculate the selection probability of a node. An agent residing at a node is activated using the activation key generated by a trusted third party to verify the misbehavior of the node. The proposed schemes reduce communication overheads and identification delays to detect misbehaving nodes in wireless ad-hoc network. Simulation results are presented to evaluate the performance of the proposed OMD and AAMD schemes.