This document provides an overview of VSAT (Very Small Aperture Terminal) network technology. It describes the key components of a VSAT network including the outdoor and indoor units, hub station, and satellite. The outdoor unit includes the antenna, transceivers, and amplifiers while the indoor unit includes the multiplexer/demultiplexer, modem, and interfaces. VSAT networks can be configured in a star topology with all traffic routed through the central hub or in a mesh topology allowing direct terminal-to-terminal communication. Common applications of VSAT networks include corporate networks, broadcasting, and interactive data services between distributed sites.
This document provides an overview of VSAT (Very Small Aperture Terminal) network technology. It describes the key components of a VSAT network including the outdoor and indoor units, hub station, and satellite. The outdoor unit includes the antenna, transceivers, and amplifiers while the indoor unit includes the multiplexer/demultiplexer, modem, and interfaces. VSAT networks can be configured in a star topology with all traffic routed through the central hub or in a mesh topology allowing direct terminal-to-terminal communication. Common applications of VSAT networks include corporate networks, broadcasting, and interactive data services between distributed sites.
Overview
WLAN Technologies - Infrared LANs, Spread Spectrum LANs, Narrowband Microwave LANs
IEEE 802.11 – Architecture, protocols, MAC layer, MAC Frame, MAC Management
Infra Red
This document discusses Very Small Aperture Terminals (VSAT) and satellite television. It provides details on VSAT components, configurations including star and mesh topologies, multiple access techniques, characteristics, advantages, limitations and uses. It also describes the working principle of satellite television including encoding, transmission via satellite, reception and features of satellite TV systems. The document is authored by Arpan Deyasi from the Dept. of ECE at RCCIIT, Kolkata and covers VSAT and DSB-TV systems for a course.
VSAT systems use small satellite dishes between 1-2 meters in diameter to connect geographically dispersed locations to a central hub station via satellite communication. They operate in the Ku band using low power transmitters between 1-2 Watts and can provide data rates from a few thousand bits per second up to 256 kbps. VSAT networks are commonly used by businesses to link remote locations and stores to a central computer system to facilitate rapid sales transactions.
VSAT (Very Small Aperture Terminal) is a satellite-based communication system that provides flexible and reliable connectivity solutions. It uses satellites to provide point-to-multipoint and point-to-point communication between a central hub station and multiple remote sites. VSAT networks offer benefits like reliability, flexibility, network management capabilities, and cost savings compared to terrestrial leased lines. Common VSAT access schemes discussed include TDMA, FDMA, DAMA, and CDMA.
VSAT (Very Small Aperture Terminal) technology allows for wireless communication via satellite using small dish antennas. A VSAT network consists of a central hub with a large antenna that communicates with multiple remote VSAT sites. The hub controls and monitors the network, sending data to the satellite which amplifies and redirects the signals to the VSATs. VSAT offers advantages like flexibility, lower installation costs than terrestrial networks, and ability to access areas without terrestrial infrastructure. Common applications of VSAT include corporate networks, internet access, distance education, and retail/banking networks. VSAT uses multiple access techniques like TDMA to allow efficient sharing of satellite bandwidth among sites.
History, Basic concepts of wireless communication, challenges in wireless communication, cellular communication, performance criteria, wireless communication standars, how call is made?
This document provides an overview of VSAT (Very Small Aperture Terminal) network technology. It describes the key components of a VSAT network including the outdoor and indoor units, hub station, and satellite. The outdoor unit includes the antenna, transceivers, and amplifiers while the indoor unit includes the multiplexer/demultiplexer, modem, and interfaces. VSAT networks can be configured in a star topology with all traffic routed through the central hub or in a mesh topology allowing direct terminal-to-terminal communication. Common applications of VSAT networks include corporate networks, broadcasting, and interactive data services between distributed sites.
Overview
WLAN Technologies - Infrared LANs, Spread Spectrum LANs, Narrowband Microwave LANs
IEEE 802.11 – Architecture, protocols, MAC layer, MAC Frame, MAC Management
Infra Red
This document discusses Very Small Aperture Terminals (VSAT) and satellite television. It provides details on VSAT components, configurations including star and mesh topologies, multiple access techniques, characteristics, advantages, limitations and uses. It also describes the working principle of satellite television including encoding, transmission via satellite, reception and features of satellite TV systems. The document is authored by Arpan Deyasi from the Dept. of ECE at RCCIIT, Kolkata and covers VSAT and DSB-TV systems for a course.
VSAT systems use small satellite dishes between 1-2 meters in diameter to connect geographically dispersed locations to a central hub station via satellite communication. They operate in the Ku band using low power transmitters between 1-2 Watts and can provide data rates from a few thousand bits per second up to 256 kbps. VSAT networks are commonly used by businesses to link remote locations and stores to a central computer system to facilitate rapid sales transactions.
VSAT (Very Small Aperture Terminal) is a satellite-based communication system that provides flexible and reliable connectivity solutions. It uses satellites to provide point-to-multipoint and point-to-point communication between a central hub station and multiple remote sites. VSAT networks offer benefits like reliability, flexibility, network management capabilities, and cost savings compared to terrestrial leased lines. Common VSAT access schemes discussed include TDMA, FDMA, DAMA, and CDMA.
VSAT (Very Small Aperture Terminal) technology allows for wireless communication via satellite using small dish antennas. A VSAT network consists of a central hub with a large antenna that communicates with multiple remote VSAT sites. The hub controls and monitors the network, sending data to the satellite which amplifies and redirects the signals to the VSATs. VSAT offers advantages like flexibility, lower installation costs than terrestrial networks, and ability to access areas without terrestrial infrastructure. Common applications of VSAT include corporate networks, internet access, distance education, and retail/banking networks. VSAT uses multiple access techniques like TDMA to allow efficient sharing of satellite bandwidth among sites.
History, Basic concepts of wireless communication, challenges in wireless communication, cellular communication, performance criteria, wireless communication standars, how call is made?
This document provides information about VSAT (Very Small Aperture Terminal) satellite networks. It defines VSAT as a two-way communication system between a satellite and ground station using a small dish antenna. It then describes VSAT remote terminal block diagrams, the importance of VSAT networks for connectivity, different VSAT configurations and topologies including star and mesh networks. It also summarizes the functions of a VSAT hub, common VSAT applications for broadcasting and interactive services, benefits of VSAT networks, and basic VSAT installation steps.
VSAT technology allows for two-way communication via satellite using small terminals. A VSAT network consists of a central hub, satellite, and numerous user terminals. VSAT networks can support internet, data, video, voice, and private/public network solutions. They are becoming increasingly popular due to their flexibility, cost efficiency, and ability to quickly provide telecom solutions for consumers and businesses.
Improvement of signal coverage using wcdma signal repeater for 3 g systemsIjrdt Journal
Wireless communication has become an indispensable technology for the society. In broadband wireless data transmission technique, 3G cellular systems are expected to provide high data rate and less probability of error. This repeater finds application in areas of poor signal coverage and connectivity. The repeater consists of a patch panel antenna for receiving WCDMA signals from the base station and amplifying the signals using a wideband RF amplifier. The signals are then retransmitted to the weak coverage area using a directional Yagi-Uda antenna. The antenna characteristics such as return loss and VSWR are measured using a Network analyzer. The component of the repeater are mounted in a stand and the performance of the entire unit was evaluated using a WCDMA generator, act as a base station, transmitting at 869 MHz and 5dBm output power. A spectrum analyzer with WCDMA analyzer is used as a receiver, the RF signal level and constellation plots with error vector magnitude are determined
VSAT systems use small aperture terminals (SATs) to provide satellite communication services directly to end users in a cost-effective way. A VSAT terminal consists of an outdoor unit with an antenna and radio frequency transceiver, and an indoor unit containing a modem and baseband processor. VSAT networks can be implemented in a star configuration, where terminals communicate through a central hub station, or a mesh configuration, where terminals can connect directly to each other.
Mobile ad-hoc networks (MANETs) were first developed in the 1970s by DARPA to allow packet radio connections between military terminals without infrastructure. MANETs allow devices to self-configure into a temporary network without centralized administration. They find applications in disaster relief, conferences, and more. Key challenges in MANETs include dynamic topology, limited bandwidth, energy constraints, and scalability issues as more devices join the network. Routing protocols must adapt to frequent changes, while providing quality of service, security, and other functions with distributed control.
VSAT is a satellite communication system that uses small antennas, typically 1-3 meters in diameter, to connect to satellites. It has two main components: an outdoor unit including the antenna and radio equipment, and an indoor unit that interfaces with user equipment. VSAT networks consist of a central hub station, geostationary satellite, and multiple remote VSAT terminals. The hub station manages the network and transmits data to the satellite at high speeds, which then broadcasts the signals to the remote VSATs. VSAT networks provide cost-effective, flexible connectivity and can support voice, video, and data transmission for applications like credit verification, stock control, and video conferencing.
This document provides an overview of the evolution of cellular networks from traditional networks to broadband networks. It discusses early cellular networks including 2G technologies like GSM and CDMA networks. It then covers 3G and 3.5G broadband cellular networks including UMTS, HSPA, HSDPA and HSUPA which enabled higher data speeds. The document reviews the history and development of cellular standards over time from 1G to 4G networks and the increasing data capabilities they provided.
The document provides an overview of cellular network concepts and architecture. It discusses how early cellular networks used a single, high-power base station, which led to capacity issues. The core idea of cellular networks was to use multiple, lower-power base stations divided into cells to increase capacity. Key concepts include cell tessellation, handoffs between cells as users move, frequency reuse between cells to avoid interference, and network architecture components like base stations, switches, and subscriber databases.
UMTS ... is 3G technology and concepts. It introduced a new radio access network called UTRAN and a new air interface called WCDMA. The core network was initially based on GSM/GPRS but was expanded with new nodes. UMTS defined four quality of service classes and new protocols were introduced for the user plane and control plane in UTRAN and between network elements. Key concepts included serving and drift RNCs for soft handover, and SRNS relocation for changing the serving RNC.
Lecture 2 evolution of mobile cellular Chandra Meena
This document provides an overview of mobile and ad hoc networks. It discusses the evolution of cellular networks from early radio communication systems through modern generations like 5G. Key topics covered include the fundamentals of wireless technologies, radio propagation mechanisms, characteristics of the wireless channel, and cellular network components and terminology. Generations of cellular standards are defined, including 1G analog networks like AMPS, 2G digital networks like GSM that enabled data services, and subsequent generations with improved capabilities.
Microwave technology can be used for LANs, extended LANs, and mobile computing. It uses either terrestrial (ground-based) links or satellite links. There are three forms of mobile computing: packet-radio networking, cellular networking, and satellite station networking. Terrestrial microwave links employ line-of-sight transmitters and receivers in the low gigahertz range, requiring stations every 30 miles, while satellite links use geosynchronous satellites to relay signals over long distances. Microwave systems offer advantages like no cables and wide bandwidth but have disadvantages like disruption from obstacles and signal absorption.
This document describes VSAT (Very Small Aperture Terminal) technology. It discusses that VSAT uses satellite communication to provide users with simple, easy-to-install equipment. The key components of a VSAT station are the outdoor unit (ODU) with antenna for uplink/downlink signals, and indoor unit (IDU) for modulation/demodulation and services. VSAT networks have a central hub for control and traffic routing to provide reliable, high availability communication even in remote areas. VSAT uses either star or mesh topologies, with star being more common due to efficiency. VSAT operates in either C-band or Ku-band frequencies, with Ku-band allowing for smaller antennas.
UMTS (Universal Mobile Telecommunications System) is a 3G mobile communication system that offers high quality wireless multimedia services. It delivers information directly to users and provides access to new services and applications regardless of location, network, or terminal used. The UMTS architecture separates the core network from the radio access network. A UMTS mobile station can operate in PS/CS mode for simultaneous services, PS-only mode, or CS-only mode. UMTS has gone through several releases to support features like HSDPA and all-IP networking.
WiFi uses radio frequencies in the 2.4GHz and 5GHz bands to enable wireless networking. It uses protocols like 802.11b, 802.11a, and 802.11g which define operating frequencies and data transmission rates. These protocols use techniques like spread spectrum and CSMA/CA to allow multiple devices to share the wireless spectrum and avoid interference between connections. Newer standards like 802.11n and WiMax promise higher speeds but come with increased complexity and costs.
Mobile cellular-telecommunication-system-revisedJohn Williams
Caller identification allows the called mobile station to display the phone number of the calling party.
2. Short Message Service (SMS) allows users to send and receive text messages to and from other mobile phones or fixed phones.
3. Facsimile (fax) services allow users to send and receive fax messages to and from other fax machines through their mobile phones.
The document discusses the history and development of 3G mobile communication technology, specifically UMTS. It provides details on:
- The evolution from 1G to 2G mobile networks and the need for 3G to support higher data rates and multimedia services.
- The standardization of UMTS through ETSI and ITU, focusing on the two selected radio transmission technologies - UTRA FDD and TDD.
- The architecture of 3G UMTS networks, including frequency reuse techniques used to maximize capacity within limited spectrum availability.
Hnc2014 wan interconnection huawei new-generation ip long haul microwave solu...eieiswe
Huawei's new-generation IP long haul microwave solution provides more flexibility, efficiency and longer transmission distances compared to previous solutions. It covers transmission over sea, land and sky via microwave channels. The document discusses challenges in developing long haul microwave technologies and how Huawei's solution addresses issues like difficult terrains, harsh environments and high capacity needs. It provides case studies of the solution's deployment for customers in scenarios such as remote mountains, islands, deserts and reconstructing networks.
These are the slides of the talk "Putting the citizens at the center of the network: Cell-free architectures" that I delivered at the IEEE 5G Summit held in Montreal today!
Chemical Reaction Effects on Free Convective Flow of a Polar Fluid from a Ver...IOSR Journals
This article deals with a study of two dimensional free convective flow of a polar fluid through a porous medium due to combined effects of thermal and mass diffusion in presence of a chemical reaction of first order. The objective of the present investigation is to analyze the free convective flow in the presence of prescribed wall heat flux and mass flux condition. The governing partial differential equations are non-dimensionalized and transformed into a system of non-similar equations. The resulting coupled nonlinear partial differential equations are solved numerically under appropriate transformed boundary conditions using an implicit finite difference scheme in combination with quasilinearisation technique. Computations are performed for a wide range of values of the various governing flow parameters of the velocity, angular velocity, temperature and species concentration profiles and results are presented graphically. The numerical results for local skin friction coefficient, couple stress coefficient, local Nusselt number and local Sherwood number are also presented. The obtained results are compared with previously published work and were to be in excellent agreement. The study reveals that the flow characteristics are profoundly influenced by the polar effects
This document proposes a new metric for measuring code readability and compares it to existing metrics. It describes collecting rules for readability from software engineers and developing a formula that incorporates these rules. A prototype application was created to apply the new metric and existing metrics (ARI, FOG, SMOG) to code samples. The results of the new metric were compared to readability percentages provided by 50 software engineers for the same samples, and were found to closely match. The new metric provides an automated way to measure code readability.
This document provides information about VSAT (Very Small Aperture Terminal) satellite networks. It defines VSAT as a two-way communication system between a satellite and ground station using a small dish antenna. It then describes VSAT remote terminal block diagrams, the importance of VSAT networks for connectivity, different VSAT configurations and topologies including star and mesh networks. It also summarizes the functions of a VSAT hub, common VSAT applications for broadcasting and interactive services, benefits of VSAT networks, and basic VSAT installation steps.
VSAT technology allows for two-way communication via satellite using small terminals. A VSAT network consists of a central hub, satellite, and numerous user terminals. VSAT networks can support internet, data, video, voice, and private/public network solutions. They are becoming increasingly popular due to their flexibility, cost efficiency, and ability to quickly provide telecom solutions for consumers and businesses.
Improvement of signal coverage using wcdma signal repeater for 3 g systemsIjrdt Journal
Wireless communication has become an indispensable technology for the society. In broadband wireless data transmission technique, 3G cellular systems are expected to provide high data rate and less probability of error. This repeater finds application in areas of poor signal coverage and connectivity. The repeater consists of a patch panel antenna for receiving WCDMA signals from the base station and amplifying the signals using a wideband RF amplifier. The signals are then retransmitted to the weak coverage area using a directional Yagi-Uda antenna. The antenna characteristics such as return loss and VSWR are measured using a Network analyzer. The component of the repeater are mounted in a stand and the performance of the entire unit was evaluated using a WCDMA generator, act as a base station, transmitting at 869 MHz and 5dBm output power. A spectrum analyzer with WCDMA analyzer is used as a receiver, the RF signal level and constellation plots with error vector magnitude are determined
VSAT systems use small aperture terminals (SATs) to provide satellite communication services directly to end users in a cost-effective way. A VSAT terminal consists of an outdoor unit with an antenna and radio frequency transceiver, and an indoor unit containing a modem and baseband processor. VSAT networks can be implemented in a star configuration, where terminals communicate through a central hub station, or a mesh configuration, where terminals can connect directly to each other.
Mobile ad-hoc networks (MANETs) were first developed in the 1970s by DARPA to allow packet radio connections between military terminals without infrastructure. MANETs allow devices to self-configure into a temporary network without centralized administration. They find applications in disaster relief, conferences, and more. Key challenges in MANETs include dynamic topology, limited bandwidth, energy constraints, and scalability issues as more devices join the network. Routing protocols must adapt to frequent changes, while providing quality of service, security, and other functions with distributed control.
VSAT is a satellite communication system that uses small antennas, typically 1-3 meters in diameter, to connect to satellites. It has two main components: an outdoor unit including the antenna and radio equipment, and an indoor unit that interfaces with user equipment. VSAT networks consist of a central hub station, geostationary satellite, and multiple remote VSAT terminals. The hub station manages the network and transmits data to the satellite at high speeds, which then broadcasts the signals to the remote VSATs. VSAT networks provide cost-effective, flexible connectivity and can support voice, video, and data transmission for applications like credit verification, stock control, and video conferencing.
This document provides an overview of the evolution of cellular networks from traditional networks to broadband networks. It discusses early cellular networks including 2G technologies like GSM and CDMA networks. It then covers 3G and 3.5G broadband cellular networks including UMTS, HSPA, HSDPA and HSUPA which enabled higher data speeds. The document reviews the history and development of cellular standards over time from 1G to 4G networks and the increasing data capabilities they provided.
The document provides an overview of cellular network concepts and architecture. It discusses how early cellular networks used a single, high-power base station, which led to capacity issues. The core idea of cellular networks was to use multiple, lower-power base stations divided into cells to increase capacity. Key concepts include cell tessellation, handoffs between cells as users move, frequency reuse between cells to avoid interference, and network architecture components like base stations, switches, and subscriber databases.
UMTS ... is 3G technology and concepts. It introduced a new radio access network called UTRAN and a new air interface called WCDMA. The core network was initially based on GSM/GPRS but was expanded with new nodes. UMTS defined four quality of service classes and new protocols were introduced for the user plane and control plane in UTRAN and between network elements. Key concepts included serving and drift RNCs for soft handover, and SRNS relocation for changing the serving RNC.
Lecture 2 evolution of mobile cellular Chandra Meena
This document provides an overview of mobile and ad hoc networks. It discusses the evolution of cellular networks from early radio communication systems through modern generations like 5G. Key topics covered include the fundamentals of wireless technologies, radio propagation mechanisms, characteristics of the wireless channel, and cellular network components and terminology. Generations of cellular standards are defined, including 1G analog networks like AMPS, 2G digital networks like GSM that enabled data services, and subsequent generations with improved capabilities.
Microwave technology can be used for LANs, extended LANs, and mobile computing. It uses either terrestrial (ground-based) links or satellite links. There are three forms of mobile computing: packet-radio networking, cellular networking, and satellite station networking. Terrestrial microwave links employ line-of-sight transmitters and receivers in the low gigahertz range, requiring stations every 30 miles, while satellite links use geosynchronous satellites to relay signals over long distances. Microwave systems offer advantages like no cables and wide bandwidth but have disadvantages like disruption from obstacles and signal absorption.
This document describes VSAT (Very Small Aperture Terminal) technology. It discusses that VSAT uses satellite communication to provide users with simple, easy-to-install equipment. The key components of a VSAT station are the outdoor unit (ODU) with antenna for uplink/downlink signals, and indoor unit (IDU) for modulation/demodulation and services. VSAT networks have a central hub for control and traffic routing to provide reliable, high availability communication even in remote areas. VSAT uses either star or mesh topologies, with star being more common due to efficiency. VSAT operates in either C-band or Ku-band frequencies, with Ku-band allowing for smaller antennas.
UMTS (Universal Mobile Telecommunications System) is a 3G mobile communication system that offers high quality wireless multimedia services. It delivers information directly to users and provides access to new services and applications regardless of location, network, or terminal used. The UMTS architecture separates the core network from the radio access network. A UMTS mobile station can operate in PS/CS mode for simultaneous services, PS-only mode, or CS-only mode. UMTS has gone through several releases to support features like HSDPA and all-IP networking.
WiFi uses radio frequencies in the 2.4GHz and 5GHz bands to enable wireless networking. It uses protocols like 802.11b, 802.11a, and 802.11g which define operating frequencies and data transmission rates. These protocols use techniques like spread spectrum and CSMA/CA to allow multiple devices to share the wireless spectrum and avoid interference between connections. Newer standards like 802.11n and WiMax promise higher speeds but come with increased complexity and costs.
Mobile cellular-telecommunication-system-revisedJohn Williams
Caller identification allows the called mobile station to display the phone number of the calling party.
2. Short Message Service (SMS) allows users to send and receive text messages to and from other mobile phones or fixed phones.
3. Facsimile (fax) services allow users to send and receive fax messages to and from other fax machines through their mobile phones.
The document discusses the history and development of 3G mobile communication technology, specifically UMTS. It provides details on:
- The evolution from 1G to 2G mobile networks and the need for 3G to support higher data rates and multimedia services.
- The standardization of UMTS through ETSI and ITU, focusing on the two selected radio transmission technologies - UTRA FDD and TDD.
- The architecture of 3G UMTS networks, including frequency reuse techniques used to maximize capacity within limited spectrum availability.
Hnc2014 wan interconnection huawei new-generation ip long haul microwave solu...eieiswe
Huawei's new-generation IP long haul microwave solution provides more flexibility, efficiency and longer transmission distances compared to previous solutions. It covers transmission over sea, land and sky via microwave channels. The document discusses challenges in developing long haul microwave technologies and how Huawei's solution addresses issues like difficult terrains, harsh environments and high capacity needs. It provides case studies of the solution's deployment for customers in scenarios such as remote mountains, islands, deserts and reconstructing networks.
These are the slides of the talk "Putting the citizens at the center of the network: Cell-free architectures" that I delivered at the IEEE 5G Summit held in Montreal today!
Chemical Reaction Effects on Free Convective Flow of a Polar Fluid from a Ver...IOSR Journals
This article deals with a study of two dimensional free convective flow of a polar fluid through a porous medium due to combined effects of thermal and mass diffusion in presence of a chemical reaction of first order. The objective of the present investigation is to analyze the free convective flow in the presence of prescribed wall heat flux and mass flux condition. The governing partial differential equations are non-dimensionalized and transformed into a system of non-similar equations. The resulting coupled nonlinear partial differential equations are solved numerically under appropriate transformed boundary conditions using an implicit finite difference scheme in combination with quasilinearisation technique. Computations are performed for a wide range of values of the various governing flow parameters of the velocity, angular velocity, temperature and species concentration profiles and results are presented graphically. The numerical results for local skin friction coefficient, couple stress coefficient, local Nusselt number and local Sherwood number are also presented. The obtained results are compared with previously published work and were to be in excellent agreement. The study reveals that the flow characteristics are profoundly influenced by the polar effects
This document proposes a new metric for measuring code readability and compares it to existing metrics. It describes collecting rules for readability from software engineers and developing a formula that incorporates these rules. A prototype application was created to apply the new metric and existing metrics (ARI, FOG, SMOG) to code samples. The results of the new metric were compared to readability percentages provided by 50 software engineers for the same samples, and were found to closely match. The new metric provides an automated way to measure code readability.
1. The document describes the development of a MATLAB software for optimizing the design of a brake for a minibike.
2. An existing minibike brake design is analyzed and mathematically modeled. The model relates key brake design parameters like pressure, width of brake lining, drum radius, to torque output.
3. The existing design is optimized by taking the maximum allowed width of brake lining (25mm) rather than the calculated width (20mm). This reduces the required drum size from 200mm to 180mm, lowering weight while maintaining torque output.
This document proposes a method for completing user profiles using their online social circles. It introduces the task of user profile completion and discusses how existing approaches do not leverage users' real social circles. The method presented uses non-negative matrix factorization to decompose a circle-profile matrix into a circle-user matrix and user-profile matrix. This allows the model to detect a user's multi-dimensional social characteristics from their various social circles. Experimental results on Facebook, LinkedIn, and Microsoft Academic Search datasets show the approach outperforms state-of-the-art methods for user profile completion.
This document proposes a novel algorithm to automatically segment overlapped and touching human chromosome images. The algorithm first obtains chromosome contours and calculates a discrete curvature function to identify concave points. Possible separation lines are then plotted by connecting concave points. Segmentation is performed by splitting the overlapped regions along these lines. The algorithm was able to successfully segment overlapped and touching chromosomes without human intervention.
Magnetic Femtotesla Inductor Coil Sensor for ELF Noise Signals-( 0.1Hz to3.0 Hz)IOSR Journals
This document describes the design of a magnetic field sensor to detect extremely low frequency (ELF) noise signals between 0.1 Hz to 3 Hz. It discusses the design of the loop antenna, transformer, and amplifier components. The antenna design aims to achieve optimal sensitivity while balancing factors like size, weight and resistance. A transformer is used to electrically isolate the antenna and match its impedance to the amplifier. Design considerations are provided to achieve a flat frequency response between the transformer's lower and upper cutoff frequencies. The overall system sensitivity depends on the transformer turn ratio and balancing the amplifier's voltage and current noise sources.
IOSR Journal of Mathematics(IOSR-JM) is an open access international journal that provides rapid publication (within a month) of articles in all areas of mathemetics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in mathematics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
This document discusses using big data technology to improve intelligent traffic systems. It proposes an architecture for an intelligent transportation system built on a big data platform with three layers: a basic business layer to collect data, a data analysis layer to analyze data using big data technologies, and an information publishing layer to share results. Key technologies discussed include calculating traffic flow and average speed on roads, querying vehicle travel paths, and identifying fake vehicles. The document argues big data can help address challenges of managing vast and diverse transportation data and improve traffic efficiency, management, and safety.
This document discusses improving quality of service in OFDMA relay networks through retransmission. It analyzes two models for OFDMA transmission - distributed permutation and contiguous permutation. It evaluates the performance of two scheduling algorithms (linear programming and greedy) on these models to select the best one. Packet loss is detected using synchronization techniques, and retransmission is used to improve throughput by resending lost packets. The goal is to enhance performance of OFDMA-based relay networks for next-generation cellular standards.
1) The document analyzes the effect of lightning strikes and thunder on television signal transmission in Nigeria.
2) Data collected from the Nigerian Television Authority in 2013-2014 showed that heavy lightning at the beginning and end of the rainy season caused image fading, breaking of images, and sometimes caused transmitters to go offline.
3) Lightning strikes damaged transmitters by affecting parts like exciters, power units, and modulators. This kept stations offline for weeks for repairs.
4) The author concludes that Nigeria's communication commission should ensure television stations are digitalized and have powerful lightning arresters installed to reduce the effects of lightning on transmissions.
This document summarizes a research paper that proposes and evaluates a novel interleaved ZCS boost DC-DC converter topology for photovoltaic interfaces. The converter uses two quasi-resonant switch blocks and lossless snubbers to achieve soft switching. Simulation results show the converter achieves reduced voltage and current ripple compared to conventional designs. A dual loop control scheme with an outer voltage loop and inner current loop is used to regulate the output. Coupling inductors between converter cells further improve transient response and reduce ripple. The proposed converter design and control scheme effectively interfaces photovoltaic systems with loads.
This document summarizes a research paper on integrating search interfaces in deep web databases for specific domains. It begins by defining the deep web and challenges in crawling it due to search forms requiring queries. It then discusses representing a search interface internally and generating meaningful queries. The paper presents an approach using semantic relationships to integrate search interfaces in a domain and generate a unified interface. It utilizes concepts and labels from a task-specific database to select query values for search forms. The goal is to crawl a selective portion of the deep web to extract content for a particular application or task.
This document describes the modeling and simulation of the transfer function characteristics of an RLC circuit using MATLAB/GUI. It begins with an introduction to RLC circuits and their importance. It then provides theoretical background on transfer functions, series RLC circuits, and step responses. The document proceeds to describe the development of a MATLAB graphical user interface to model and simulate an RLC circuit. It provides examples of simulations using different component values and discusses the results. Validation of the simulator is also presented by comparing results from the GUI simulator to manual calculations. The conclusion is that the GUI simulator allows for easy understanding and analysis of RLC circuit behavior as components values vary.
This document summarizes a research paper about a simple signature recognition system designed using MATLAB. The system extracts features from signatures using invariant central moment and modified Zernike moment for invariant feature extraction. It is divided into preprocessing, feature extraction, and recognition/verification. Preprocessing prepares the signature image for processing. Feature extraction uses invariant central moments and Zernike moments. Recognition uses a backpropagation neural network for classification. The system was tested on a database of 500 signatures from 50 individuals, achieving high accuracy and low computational complexity.
This document summarizes a study on optimizing and reducing the weight of a universal joint yoke through the use of composite materials. The study first analyzes a conventional universal joint yoke made of SM45C steel using finite element analysis. It then models modified universal joint yokes made of carbon/epoxy composite and Kevlar/epoxy composite. Calculations of torsional strength, buckling strength, and bending natural frequency show that both composite designs meet requirements while reducing weight compared to steel. Static stress analyses and modal analyses using FEA are presented and compared between materials. The study aims to improve mechanical properties and reduce weight of universal joints through composite material optimization.
Privacy Preserving Clustering on Distorted dataIOSR Journals
- The document discusses privacy-preserving clustering on distorted data using singular value decomposition (SVD) and sparsified singular value decomposition (SSVD).
- It applies SVD and SSVD to distort a real-world dataset of 100 terrorists with 42 attributes, generating distorted datasets.
- K-means clustering is then performed on the original and distorted datasets for different numbers of clusters (k). The results show that SSVD more effectively groups the data objects into clusters compared to the original and SVD-distorted datasets, while preserving data privacy as measured by various metrics.
A Brief Review on Advance Acoustic Control System Process of Automotive MufflerIOSR Journals
This document provides a review of advance acoustic control systems used in automotive mufflers. It begins with an introduction explaining how mufflers reduce engine exhaust noise. It then discusses the basic requirements and design procedures for mufflers, including reactive, absorptive, and combination muffler designs. The document reviews several past studies on muffler design and analysis using modeling, simulation, and testing. It evaluates different muffler types and parameters that influence noise reduction effectiveness. In summary, the document provides an overview of muffler design and recent research on using various acoustic and modeling techniques to optimize muffler performance.
This document summarizes a research study that analyzed the performance of students working on different chairs and tables of varying heights. Two students of different heights assembled and disassembled a toy car on five tables with rotations of five chairs. The time taken was observed and production rates were calculated and compared. The results showed that the taller student was more comfortable and efficient with the given chair-table combinations. Ergonomics aims to design workspaces that balance worker characteristics and task demands to enhance productivity, safety, and well-being. Consideration of anthropometrics and posture is important for office furniture to properly fit its users.
The document discusses optimizing surface roughness values in hard turning of AISI 52100 steel through experimentation using tribological (speed, feed, depth of cut) parameters. Experiments were conducted on a CNC lathe using cBN inserts to machine AISI 52100 steel hardened to 60 HRC. A Taguchi L9 orthogonal array was used as the experimental design to study the effects of cutting parameters on roughness. Regression analysis was performed to develop relationships between parameters and roughness to optimize values with 98.27% accuracy and 4.69% error.
This document presents the conceptual design of a new "Lotos" motorcar. The design was inspired by the shape of lotus flower petals and aims to emulate their graceful yet powerful form. The conceptual design process began with sketches of potential shapes and symbols. A 3D computer model was then developed using polygonal extrusion in 3ds Max software. Various design elements were smoothed and given materials. Renderings were produced using V-Ray to visualize the final shaded conceptual model. The goal of the conceptual design was to create a high-performance sports car with the elegance and vigor suggested by its namesake, the lotus flower.
This document provides an overview of VSAT (Very Small Aperture Terminal) technology. It discusses VSAT components, installation, advantages, applications including distance learning, network architecture, and multiple access techniques. A VSAT consists of an outdoor transceiver and indoor data processing unit. Information is sent to satellites and transmitted to remote VSAT sites. VSATs offer flexible, low-cost networks for applications such as corporate networks, internet access, and distance education. Distance learning uses VSATs to transmit educational content from hub to remote areas.
International Journal of Engineering Research and Development (IJERD)IJERD Editor
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yahoo journals, bing journals, International Journal of Engineering Research and Development, google journals, hard copy of journal
- Unicast is for direct host-to-host communication, broadcast sends packets to all nodes in a domain simultaneously, and multicast sends to a selected group of users who requested the broadcast.
- A broadcast domain is an area where all devices can receive broadcasts, while a collision domain is where only one device can transmit at a time.
- Switches join LANs into a single broadcast domain but isolate them so problems don't propagate, and maintain separate collision domains. VLANs can create virtual broadcast domains across switches.
This document provides an introduction to wireless communications and networks. It discusses the key components of a communication system including the source, transmitter, channel, receiver and output transducer. It also describes examples of wireless communication systems such as cellular telephone systems, remote controllers and wireless LANs. The document summarizes the characteristics of 1G, 2G and 3G wireless systems and standards. It also discusses wireless local area networks, personal area networks using Bluetooth, and mobile ad-hoc networks. Finally, it outlines the conceptual layers in a wireless network including the physical, data link, network and application layers.
The document provides information about Damodar Valley Corporation (DVC), a river valley project in India. It discusses that DVC was the first multipurpose river valley project of independent India established in 1948. It generates, transmits and distributes electricity and facilitates irrigation and water supply. The document also provides details about DVC's infrastructure including its power generation capacity, transmission lines, and command area covered.
Design and implementation of heterogeneous surface gateway for underwater aco...IJECEIAES
Underwater Acoustic Sensor Networks (UASNs) are used for diverse purposes such as pollution monitoring, disaster prevention and industrial sensing in the oceans. Especially, UASNs are mainly focusing on monitoring various underwater environmental data and delivering the data to a monitoring center where nearby or far from the deployed area. To reliably deliver the data, a surface gateway should convert acoustic signal to RF (Radio Frequency) signal. In this paper, we devise a multiple interfaces-based surface gateway that can connect both a cellular network and a Zigbee network. Depends on the service requirement, the surface gateway can easily adopt each wireless interface and relay the data to a low power ZigBee network or a long range CDMA network.
The document discusses the evolution of telephony from 1876 to the present, including the development of mobile telephony. It describes the public switched telephone network and how it connects to subscribers. It also covers multiple access procedures used in mobile networks, including FDMA, TDMA, CDMA, and SDMA. Finally, it discusses technologies that enabled mobile computing through telephony networks, such as computer telephony interface, intelligent networks, and interactive voice response systems.
An overview of how VSAT system works-converted.pdfinter sat
Every transmission goes to the hub station first, which then retransmits the signals via the satellite reaching the VSAT of the end users. You can always contact a good VSAT Engineer in Africa to deploy this system at your property. Contact us today
The document discusses the evolution of wireless communication technologies through generations from 2G to 4G. It describes the key characteristics and speed capabilities of each generation. It also provides details on various wireless networking components and concepts such as channel access schemes, radio signals, BTS, BSC, MSC, HLR, AuC, EIR and SMSC.
Chapter 1 AI is used in Customer Relationship Management (CRM):.pptxfilembarketema
Certainly! Here are some examples of how AI is used in Customer Relationship Management (CRM):
Chatbots: AI-powered chatbots are used in CRM systems to provide automated customer support and assistance. Chatbots can handle a wide range of customer inquiries, answer frequently asked questions, and provide relevant information in real-time. They can engage in natural language conversations, understand customer intent, and provide personalized recommendations or solutions.
Sentiment Analysis: AI algorithms can analyze customer interactions, such as emails, social media posts, and chat transcripts, to determine customer sentiment and emotions. Sentiment analysis helps CRM systems understand customer satisfaction levels, identify potential issues or concerns, and take proactive measures to address them.
Personalization: AI enables CRM systems to deliver personalized experiences to customers. By analyzing customer data, purchase history, browsing behavior, and preferences, AI algorithms can generate personalized product recommendations, targeted marketing campaigns, and customized offers to enhance customer engagement and satisfaction.
Lead Scoring and Qualification: AI can assist in lead scoring and qualification processes. By analyzing historical data and customer behavior patterns, AI algorithms can predict the likelihood of a lead converting into a customer. This helps sales teams prioritize their efforts and allocate resources effectively to high-potential leads, improving conversion rates and sales efficiency.
Predictive Analytics: AI algorithms can analyze customer data and historical patterns to make predictions about customer behavior, such as likelihood to churn or cross-sell/up-sell opportunities. These predictions help CRM systems identify the most effective strategies for customer retention and revenue growth.
Voice and Speech Analytics: AI-powered voice and speech analytics tools can analyze customer calls and extract valuable insights. These tools can identify keywords, sentiment, and speech patterns to understand customer needs, identify common issues, and provide feedback for agent training and process improvement.
Social Media Monitoring: AI algorithms can monitor social media platforms to track brand mentions, customer feedback, and sentiment. This helps CRM systems identify customer concerns, engage in social listening, and respond promptly to customer queries or complaints, improving overall customer satisfaction and brand reputation.
Customer Segmentation: AI can assist in segmenting customers based on various criteria, such as demographics, purchase history, interests, and behavior. This enables CRM systems to tailor marketing campaigns, promotions, and communication strategies to specific customer segments, improving targeting and response rates.
Customer Lifetime Value (CLV) Prediction: This helps CRM
This document summarizes key aspects of satellite communications technology. It describes transponders that relay signals between satellites and Earth, how satellites control their orientation, and how they are powered by solar cells. It discusses low Earth orbiting satellites and very small aperture terminals that allow communication across wide areas. The document outlines domestic, regional, and international satellite types and some advantages of satellite circuits like independent coverage over distance.
Comparison between gsm & cdma najmul hoque munshiNajmulHoqueMunshi
This document compares and contrasts GSM and CDMA cellular communication technologies. It begins with an introduction to cellular concepts and architectures. It then describes GSM, including that it uses TDMA and operates at 900/1800 MHz bands. The GSM architecture includes components like the BTS, BSC, HLR, VLR, and AuC. It then describes CDMA, including that it uses spread spectrum technology and references GPS for timing. The CDMA architecture spreads each user's signal over the entire bandwidth using unique codes. Finally, it lists the main differences between GSM and CDMA, such as their use of different multiple access technologies and CDMA providing better security through encryption.
The document provides an overview of training conducted by SYSTEL on wireless communication concepts. The training covered basics of telecommunication systems including modulation techniques, multiple access techniques, antenna systems, wireless broadband, two-way radio systems, mobility networks, and operating system essentials. The training documentation included detailed sections on each of these topics.
Basic of 3 g technologies (digi lab_project).pptx [repaired]Shahrin Ahammad
The document provides an overview of 3G standards and the radio access network architecture. It discusses the reasons for switching from 2G to 3G technologies, including higher data rates and improved security. It then describes the components of the UMTS network architecture, including user equipment, Node B base stations, radio network controllers, mobile switching centers, and connections to external networks. The document also compares 2G and 3G network structures.
A Survey on Emerging WiMAX Antenna Technologies and Slotted Microstrip Patch ...IRJET Journal
This document discusses various antenna technologies for WiMAX applications, including SISO, SIMO, MISO, MIMO and AAS modes. It also reviews slotted microstrip patch antennas, specifically double C-slot and C-slot designs. Key findings include:
1) Slotted microstrip patch antennas can improve gain, return loss and VSWR over conventional patch antennas for WiMAX.
2) A double C-slot design achieved a return loss of -31.6 dB and gain of 6.4 dBi, outperforming a C-slot antenna.
3) Slotted designs provide a 37% reduction in antenna size compared to conventional square patches.
VSAT system involves a one-way or two-way satellite ground station that features a dish antenna smaller than three meters across visit online for more info about vsat system.
This document summarizes several wireless communication technologies and power generation methods. It discusses Global Positioning Systems (GPS), General Packet Radio Service (GPRS), Global System for Mobile Communications (GSM), Code Division Multiple Access (CDMA), 3G, 5G, Wi-Fi, WiMAX, Bluetooth, Near Field Communication (NFC), Infrared (IR), Radio Frequency (RF), socket programming, Local Area Networks (LAN), Wide Area Networks (WAN), and power generation using solar, wind, geothermal, batteries, AC/DC power, nuclear, fossil fuels, and hydro sources.
This document discusses satellite communications and provides an overview of key concepts:
- Satellite communications systems have two main components - the satellite in orbit which receives and transmits signals, and ground stations that send signals to and receive signals from the satellite.
- Satellites are used for various applications including telecommunications, cellular networks, television broadcasting, maritime communications, land mobile communications, aircraft messaging, and global positioning.
- Technological aspects discussed include error correction techniques like forward-error correction and automatic-repeat-request, hybrid satellite-terrestrial networks, and using protocols like TCP/IP over satellite links.
The document summarizes VSAT technology, including its definition, history, components, uses, and future applications. Key points include:
- VSAT stands for Very Small Aperture Terminal and uses small satellite dishes less than 3.8 meters to transmit and receive data via satellite.
- The technology has been in development since the 1920s and was first used commercially in the 1960s for satellite television broadcasts.
- Modern VSAT systems use components like antennas, BUCs, LNBs, and indoor modems to transmit and receive data via geosynchronous satellites.
- Applications include broadband internet access, VoIP, and monitoring systems. The maritime VSAT market was over $400 million in 2007.
- Future
The Iridium satellite system allows for global mobile communications through a constellation of 66 low Earth orbit satellites. It uses a digitally switched network architecture to provide telephone service anywhere on Earth. Each satellite is crosslinked to four other satellites to relay digital information and determine the best routing path for calls through inter-satellite links and ground-based gateways. The unique feature of the Iridium system is its crosslinks that allow two-way global communications even when the destination location is unknown.
This document provides a technical review of secure banking using RSA and AES encryption methodologies. It discusses how RSA and AES are commonly used encryption standards for secure data transmission between ATMs and bank servers. The document first provides background on ATM security measures and risks of attacks. It then reviews related work analyzing encryption techniques. The document proposes using a one-time password in addition to a PIN for ATM authentication. It concludes that implementing encryption standards like RSA and AES can make transactions more secure and build trust in online banking.
This document analyzes the performance of various modulation schemes for achieving energy efficient communication over fading channels in wireless sensor networks. It finds that for long transmission distances, low-order modulations like BPSK are optimal due to their lower SNR requirements. However, as transmission distance decreases, higher-order modulations like 16-QAM and 64-QAM become more optimal since they can transmit more bits per symbol, outweighing their higher SNR needs. Simulations show lifetime extensions up to 550% are possible in short-range networks by using higher-order modulations instead of just BPSK. The optimal modulation depends on transmission distance and balancing the energy used by electronic components versus power amplifiers.
This document provides a review of mobility management techniques in vehicular ad hoc networks (VANETs). It discusses three modes of communication in VANETs: vehicle-to-infrastructure (V2I), vehicle-to-vehicle (V2V), and hybrid vehicle (HV) communication. For each communication mode, different mobility management schemes are required due to their unique characteristics. The document also discusses mobility management challenges in VANETs and outlines some open research issues in improving mobility management for seamless communication in these dynamic networks.
This document provides a review of different techniques for segmenting brain MRI images to detect tumors. It compares the K-means and Fuzzy C-means clustering algorithms. K-means is an exclusive clustering algorithm that groups data points into distinct clusters, while Fuzzy C-means is an overlapping clustering algorithm that allows data points to belong to multiple clusters. The document finds that Fuzzy C-means requires more time for brain tumor detection compared to other methods like hierarchical clustering or K-means. It also reviews related work applying these clustering algorithms to segment brain MRI images.
1) The document simulates and compares the performance of AODV and DSDV routing protocols in a mobile ad hoc network under three conditions: when users are fixed, when users move towards the base station, and when users move away from the base station.
2) The results show that both protocols have higher packet delivery and lower packet loss when users are either fixed or moving towards the base station, since signal strength is better in those scenarios. Performance degrades when users move away from the base station due to weaker signals.
3) AODV generally has better performance than DSDV, with higher throughput and packet delivery rates observed across the different user mobility conditions.
This document describes the design and implementation of 4-bit QPSK and 256-bit QAM modulation techniques using MATLAB. It compares the two techniques based on SNR, BER, and efficiency. The key steps of implementing each technique in MATLAB are outlined, including generating random bits, modulation, adding noise, and measuring BER. Simulation results show scatter plots and eye diagrams of the modulated signals. A table compares the results, showing that 256-bit QAM provides better performance than 4-bit QPSK. The document concludes that QAM modulation is more effective for digital transmission systems.
The document proposes a hybrid technique using Anisotropic Scale Invariant Feature Transform (A-SIFT) and Robust Ensemble Support Vector Machine (RESVM) to accurately identify faces in images. A-SIFT improves upon traditional SIFT by applying anisotropic scaling to extract richer directional keypoints. Keypoints are processed with RESVM and hypothesis testing to increase accuracy above 95% by repeatedly reprocessing images until the threshold is met. The technique was tested on similar and different facial images and achieved better results than SIFT in retrieval time and reduced keypoints.
This document studies the effects of dielectric superstrate thickness on microstrip patch antenna parameters. Three types of probes-fed patch antennas (rectangular, circular, and square) were designed to operate at 2.4 GHz using Arlondiclad 880 substrate. The antennas were tested with and without an Arlondiclad 880 superstrate of varying thicknesses. It was found that adding a superstrate slightly degraded performance by lowering the resonant frequency and increasing return loss and VSWR, while decreasing bandwidth and gain. Specifically, increasing the superstrate thickness or dielectric constant resulted in greater changes to the antenna parameters.
This document describes a wireless environment monitoring system that utilizes soil energy as a sustainable power source for wireless sensors. The system uses a microbial fuel cell to generate electricity from the microbial activity in soil. Two microbial fuel cells were created using different soil types and various additives to produce different current and voltage outputs. An electronic circuit was designed on a printed circuit board with components like a microcontroller and ZigBee transceiver. Sensors for temperature and humidity were connected to the circuit to monitor the environment wirelessly. The system provides a low-cost way to power remote sensors without needing battery replacement and avoids the high costs of wiring a power source.
1) The document proposes a model for a frequency tunable inverted-F antenna that uses ferrite material.
2) The resonant frequency of the antenna can be significantly shifted from 2.41GHz to 3.15GHz, a 31% shift, by increasing the static magnetic field placed on the ferrite material.
3) Altering the permeability of the ferrite allows tuning of the antenna's resonant frequency without changing the physical dimensions, providing flexibility to operate over a wide frequency range.
This document summarizes a research paper that presents a speech enhancement method using stationary wavelet transform. The method first classifies speech into voiced, unvoiced, and silence regions based on short-time energy. It then applies different thresholding techniques to the wavelet coefficients of each region - modified hard thresholding for voiced speech, semi-soft thresholding for unvoiced speech, and setting coefficients to zero for silence. Experimental results using speech from the TIMIT database corrupted with white Gaussian noise at various SNR levels show improved performance over other popular denoising methods.
This document reviews the design of an energy-optimized wireless sensor node that encrypts data for transmission. It discusses how sensing schemes that group nodes into clusters and transmit aggregated data can reduce energy consumption compared to individual node transmissions. The proposed node design calculates the minimum transmission power needed based on received signal strength and uses a periodic sleep/wake cycle to optimize energy when not sensing or transmitting. It aims to encrypt data at both the node and network level to further optimize energy usage for wireless communication.
This document discusses group consumption modes. It analyzes factors that impact group consumption, including external environmental factors like technological developments enabling new forms of online and offline interactions, as well as internal motivational factors at both the group and individual level. The document then proposes that group consumption modes can be divided into four types based on two dimensions: vertical (group relationship intensity) and horizontal (consumption action period). These four types are instrument-oriented, information-oriented, enjoyment-oriented, and relationship-oriented consumption modes. Finally, the document notes that consumption modes are dynamic and can evolve over time.
The document summarizes a study of different microstrip patch antenna configurations with slotted ground planes. Three antenna designs were proposed and their performance evaluated through simulation: a conventional square patch, an elliptical patch, and a star-shaped patch. All antennas were mounted on an FR4 substrate. The effects of adding different slot patterns to the ground plane on resonance frequency, bandwidth, gain and efficiency were analyzed parametrically. Key findings were that reshaping the patch and adding slots increased bandwidth and shifted resonance frequency. The elliptical and star patches in particular performed better than the conventional design. Three antenna configurations were selected for fabrication and measurement based on the simulations: a conventional patch with a slot under the patch, an elliptical patch with slots
1) The document describes a study conducted to improve call drop rates in a GSM network through RF optimization.
2) Drive testing was performed before and after optimization using TEMS software to record network parameters like RxLevel, RxQuality, and events.
3) Analysis found call drops were occurring due to issues like handover failures between sectors, interference from adjacent channels, and overshooting due to antenna tilt.
4) Corrective actions taken included defining neighbors between sectors, adjusting frequencies to reduce interference, and lowering the mechanical tilt of an antenna.
5) Post-optimization drive testing showed improvements in RxLevel, RxQuality, and a reduction in dropped calls.
This document describes the design of an intelligent autonomous wheeled robot that uses RF transmission for communication. The robot has two modes - automatic mode where it can make its own decisions, and user control mode where a user can control it remotely. It is designed using a microcontroller and can perform tasks like object recognition using computer vision and color detection in MATLAB, as well as wall painting using pneumatic systems. The robot's movement is controlled by DC motors and it uses sensors like ultrasonic sensors and gas sensors to navigate autonomously. RF transmission allows communication between the robot and a remote control unit. The overall aim is to develop a low-cost robotic system for industrial applications like material handling.
This document reviews cryptography techniques to secure the Ad-hoc On-Demand Distance Vector (AODV) routing protocol in mobile ad-hoc networks. It discusses various types of attacks on AODV like impersonation, denial of service, eavesdropping, black hole attacks, wormhole attacks, and Sybil attacks. It then proposes using the RC6 cryptography algorithm to secure AODV by encrypting data packets and detecting and removing malicious nodes launching black hole attacks. Simulation results show that after applying RC6, the packet delivery ratio and throughput of AODV increase while delay decreases, improving the security and performance of the network under attack.
The document describes a proposed modification to the conventional Booth multiplier that aims to increase its speed by applying concepts from Vedic mathematics. Specifically, it utilizes the Urdhva Tiryakbhyam formula to generate all partial products concurrently rather than sequentially. The proposed 8x8 bit multiplier was coded in VHDL, simulated, and found to have a path delay 44.35% lower than a conventional Booth multiplier, demonstrating its potential for higher speed.
This document discusses image deblurring techniques. It begins by introducing image restoration and focusing on image deblurring. It then discusses challenges with image deblurring being an ill-posed problem. It reviews existing approaches to screen image deconvolution including estimating point spread functions and iteratively estimating blur kernels and sharp images. The document also discusses handling spatially variant blur and summarizes the relationship between the proposed method and previous work for different blur types. It proposes using color filters in the aperture to exploit parallax cues for segmentation and blur estimation. Finally, it proposes moving the image sensor circularly during exposure to prevent high frequency attenuation from motion blur.
This document describes modeling an adaptive controller for an aircraft roll control system using PID, fuzzy-PID, and genetic algorithm. It begins by introducing the aircraft roll control system and motivation for developing an adaptive controller to minimize errors from noisy analog sensor signals. It then provides the mathematical model of aircraft roll dynamics and describes modeling the real-time flight control system in MATLAB/Simulink. The document evaluates PID, fuzzy-PID, and PID-GA (genetic algorithm) controllers for aircraft roll control and finds that the PID-GA controller delivers the best performance.
Why You Should Replace Windows 11 with Nitrux Linux 3.5.0 for enhanced perfor...SOFTTECHHUB
The choice of an operating system plays a pivotal role in shaping our computing experience. For decades, Microsoft's Windows has dominated the market, offering a familiar and widely adopted platform for personal and professional use. However, as technological advancements continue to push the boundaries of innovation, alternative operating systems have emerged, challenging the status quo and offering users a fresh perspective on computing.
One such alternative that has garnered significant attention and acclaim is Nitrux Linux 3.5.0, a sleek, powerful, and user-friendly Linux distribution that promises to redefine the way we interact with our devices. With its focus on performance, security, and customization, Nitrux Linux presents a compelling case for those seeking to break free from the constraints of proprietary software and embrace the freedom and flexibility of open-source computing.
Removing Uninteresting Bytes in Software FuzzingAftab Hussain
Imagine a world where software fuzzing, the process of mutating bytes in test seeds to uncover hidden and erroneous program behaviors, becomes faster and more effective. A lot depends on the initial seeds, which can significantly dictate the trajectory of a fuzzing campaign, particularly in terms of how long it takes to uncover interesting behaviour in your code. We introduce DIAR, a technique designed to speedup fuzzing campaigns by pinpointing and eliminating those uninteresting bytes in the seeds. Picture this: instead of wasting valuable resources on meaningless mutations in large, bloated seeds, DIAR removes the unnecessary bytes, streamlining the entire process.
In this work, we equipped AFL, a popular fuzzer, with DIAR and examined two critical Linux libraries -- Libxml's xmllint, a tool for parsing xml documents, and Binutil's readelf, an essential debugging and security analysis command-line tool used to display detailed information about ELF (Executable and Linkable Format). Our preliminary results show that AFL+DIAR does not only discover new paths more quickly but also achieves higher coverage overall. This work thus showcases how starting with lean and optimized seeds can lead to faster, more comprehensive fuzzing campaigns -- and DIAR helps you find such seeds.
- These are slides of the talk given at IEEE International Conference on Software Testing Verification and Validation Workshop, ICSTW 2022.
TrustArc Webinar - 2024 Global Privacy SurveyTrustArc
How does your privacy program stack up against your peers? What challenges are privacy teams tackling and prioritizing in 2024?
In the fifth annual Global Privacy Benchmarks Survey, we asked over 1,800 global privacy professionals and business executives to share their perspectives on the current state of privacy inside and outside of their organizations. This year’s report focused on emerging areas of importance for privacy and compliance professionals, including considerations and implications of Artificial Intelligence (AI) technologies, building brand trust, and different approaches for achieving higher privacy competence scores.
See how organizational priorities and strategic approaches to data security and privacy are evolving around the globe.
This webinar will review:
- The top 10 privacy insights from the fifth annual Global Privacy Benchmarks Survey
- The top challenges for privacy leaders, practitioners, and organizations in 2024
- Key themes to consider in developing and maintaining your privacy program
Let's Integrate MuleSoft RPA, COMPOSER, APM with AWS IDP along with Slackshyamraj55
Discover the seamless integration of RPA (Robotic Process Automation), COMPOSER, and APM with AWS IDP enhanced with Slack notifications. Explore how these technologies converge to streamline workflows, optimize performance, and ensure secure access, all while leveraging the power of AWS IDP and real-time communication via Slack notifications.
Building Production Ready Search Pipelines with Spark and MilvusZilliz
Spark is the widely used ETL tool for processing, indexing and ingesting data to serving stack for search. Milvus is the production-ready open-source vector database. In this talk we will show how to use Spark to process unstructured data to extract vector representations, and push the vectors to Milvus vector database for search serving.
AI 101: An Introduction to the Basics and Impact of Artificial IntelligenceIndexBug
Imagine a world where machines not only perform tasks but also learn, adapt, and make decisions. This is the promise of Artificial Intelligence (AI), a technology that's not just enhancing our lives but revolutionizing entire industries.
Unlocking Productivity: Leveraging the Potential of Copilot in Microsoft 365, a presentation by Christoforos Vlachos, Senior Solutions Manager – Modern Workplace, Uni Systems
In the rapidly evolving landscape of technologies, XML continues to play a vital role in structuring, storing, and transporting data across diverse systems. The recent advancements in artificial intelligence (AI) present new methodologies for enhancing XML development workflows, introducing efficiency, automation, and intelligent capabilities. This presentation will outline the scope and perspective of utilizing AI in XML development. The potential benefits and the possible pitfalls will be highlighted, providing a balanced view of the subject.
We will explore the capabilities of AI in understanding XML markup languages and autonomously creating structured XML content. Additionally, we will examine the capacity of AI to enrich plain text with appropriate XML markup. Practical examples and methodological guidelines will be provided to elucidate how AI can be effectively prompted to interpret and generate accurate XML markup.
Further emphasis will be placed on the role of AI in developing XSLT, or schemas such as XSD and Schematron. We will address the techniques and strategies adopted to create prompts for generating code, explaining code, or refactoring the code, and the results achieved.
The discussion will extend to how AI can be used to transform XML content. In particular, the focus will be on the use of AI XPath extension functions in XSLT, Schematron, Schematron Quick Fixes, or for XML content refactoring.
The presentation aims to deliver a comprehensive overview of AI usage in XML development, providing attendees with the necessary knowledge to make informed decisions. Whether you’re at the early stages of adopting AI or considering integrating it in advanced XML development, this presentation will cover all levels of expertise.
By highlighting the potential advantages and challenges of integrating AI with XML development tools and languages, the presentation seeks to inspire thoughtful conversation around the future of XML development. We’ll not only delve into the technical aspects of AI-powered XML development but also discuss practical implications and possible future directions.
Cosa hanno in comune un mattoncino Lego e la backdoor XZ?Speck&Tech
ABSTRACT: A prima vista, un mattoncino Lego e la backdoor XZ potrebbero avere in comune il fatto di essere entrambi blocchi di costruzione, o dipendenze di progetti creativi e software. La realtà è che un mattoncino Lego e il caso della backdoor XZ hanno molto di più di tutto ciò in comune.
Partecipate alla presentazione per immergervi in una storia di interoperabilità, standard e formati aperti, per poi discutere del ruolo importante che i contributori hanno in una comunità open source sostenibile.
BIO: Sostenitrice del software libero e dei formati standard e aperti. È stata un membro attivo dei progetti Fedora e openSUSE e ha co-fondato l'Associazione LibreItalia dove è stata coinvolta in diversi eventi, migrazioni e formazione relativi a LibreOffice. In precedenza ha lavorato a migrazioni e corsi di formazione su LibreOffice per diverse amministrazioni pubbliche e privati. Da gennaio 2020 lavora in SUSE come Software Release Engineer per Uyuni e SUSE Manager e quando non segue la sua passione per i computer e per Geeko coltiva la sua curiosità per l'astronomia (da cui deriva il suo nickname deneb_alpha).
Infrastructure Challenges in Scaling RAG with Custom AI modelsZilliz
Building Retrieval-Augmented Generation (RAG) systems with open-source and custom AI models is a complex task. This talk explores the challenges in productionizing RAG systems, including retrieval performance, response synthesis, and evaluation. We’ll discuss how to leverage open-source models like text embeddings, language models, and custom fine-tuned models to enhance RAG performance. Additionally, we’ll cover how BentoML can help orchestrate and scale these AI components efficiently, ensuring seamless deployment and management of RAG systems in the cloud.
Essentials of Automations: The Art of Triggers and Actions in FMESafe Software
In this second installment of our Essentials of Automations webinar series, we’ll explore the landscape of triggers and actions, guiding you through the nuances of authoring and adapting workspaces for seamless automations. Gain an understanding of the full spectrum of triggers and actions available in FME, empowering you to enhance your workspaces for efficient automation.
We’ll kick things off by showcasing the most commonly used event-based triggers, introducing you to various automation workflows like manual triggers, schedules, directory watchers, and more. Plus, see how these elements play out in real scenarios.
Whether you’re tweaking your current setup or building from the ground up, this session will arm you with the tools and insights needed to transform your FME usage into a powerhouse of productivity. Join us to discover effective strategies that simplify complex processes, enhancing your productivity and transforming your data management practices with FME. Let’s turn complexity into clarity and make your workspaces work wonders!
UiPath Test Automation using UiPath Test Suite series, part 5DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 5. In this session, we will cover CI/CD with devops.
Topics covered:
CI/CD with in UiPath
End-to-end overview of CI/CD pipeline with Azure devops
Speaker:
Lyndsey Byblow, Test Suite Sales Engineer @ UiPath, Inc.
Dr. Sean Tan, Head of Data Science, Changi Airport Group
Discover how Changi Airport Group (CAG) leverages graph technologies and generative AI to revolutionize their search capabilities. This session delves into the unique search needs of CAG’s diverse passengers and customers, showcasing how graph data structures enhance the accuracy and relevance of AI-generated search results, mitigating the risk of “hallucinations” and improving the overall customer journey.
GraphSummit Singapore | The Art of the Possible with Graph - Q2 2024Neo4j
Neha Bajwa, Vice President of Product Marketing, Neo4j
Join us as we explore breakthrough innovations enabled by interconnected data and AI. Discover firsthand how organizations use relationships in data to uncover contextual insights and solve our most pressing challenges – from optimizing supply chains, detecting fraud, and improving customer experiences to accelerating drug discoveries.
Driving Business Innovation: Latest Generative AI Advancements & Success StorySafe Software
Are you ready to revolutionize how you handle data? Join us for a webinar where we’ll bring you up to speed with the latest advancements in Generative AI technology and discover how leveraging FME with tools from giants like Google Gemini, Amazon, and Microsoft OpenAI can supercharge your workflow efficiency.
During the hour, we’ll take you through:
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1. IOSR Journal of Electronics and Communication Engineering (IOSR-JECE)
e-ISSN: 2278-2834,p- ISSN: 2278-8735.Volume 10, Issue 1, Ver. III (Jan - Feb. 2015), PP 18-24
www.iosrjournals.org
DOI: 10.9790/2834-10131824 www.iosrjournals.org 18 | Page
VSAT Network Overview
Khalid Abdalrazig Ibrahim Hassan1
Dr. Amin Babiker A/Nabi Mustafa2
Department of Communications, Faculty of Engineering, Al-Neelain University Khartoum, Sudan
Department of Communications, Faculty of Engineering, Al-Neelain University Dean of
Faculty Khartoum, Sudan
Abstract: VSAT technology is a telecommunication system based on wireless satellite technology . the term
vsat stands for "small aperture terminal". As the definition itself dictates , vsat technology of small satellite
earth station , this paper shows vsat network technology .
Keywords: vsat ,outdoor unit, indoor unit ,hub ,security, earth station.
I. Introduction
VSAT (Very Small Aperture Terminal) describes a small terminal that can be used for two-way
communications via satellite. VSAT networks offer value-added satellite-based services capable of supporting
the Internet, data, video, LAN, voice/fax communications, and can provide powerful private and public network
communication solutions. They are becoming increasingly popular, as VSATs are a single, flexible
communications platform that can be installed quickly and cost efficiently to provide telecoms solutions for
consumers, governments and corporations.
The benefits of VSAT technology are being realized in many sectors, both private and public. From
banks to administrations, schools, hospitals and rural telecommunications, VSATs are being seized upon to
elevate economic, educational, and health standards.
VSATs have been in use for more than 20 years and, with already millions installed all over the world,
VSATs are a mature and proven technology. [7]
VSAT comprises of two modules viz. an outdoor unit and an indoor unit. Outdoor unit mainly houses
Antenna, feed horn,RF Transceiver,LNA,Power amplifier. The antenna size is typically 1.8 or 2.4 meter in
diameter, although smaller antennas are also in use. The indoor unit functions as mux-demux, modem and
interfaces with the end user equipments like PCs, LANs, Telephones or an EPABX. Following diagram
describes typical schematic consisting various VSAT subsystems. [1]
1.1Vsat outdoor unit
The Outdoor unit is usually mounted near the antenna systems outside hence the name. It consists of
RF frequency converters (Up/Down converter), Power Amplifier, Low Noise Amplifier (LNA), OMT and
Antenna system.
The Up/Down converters convert frequencies IF to RF frequencies and vice versa. For example, Up
converter converts 70MHz to 6175 MHz and Down converter converts 3950MHz to 70MHz for C band
application. Power Amplifier will amplify the signal before transmitting to the feed horn of the Antenna system.
LNAs are designed to amplify the noise added received signal received from the satellite. It is designed such
that it will amplify the signal and not the noise. Noise temperature defines LNA performance. Antenna system
houses reflector,feed horn,mount and cables. VSAT antenna usually varies from 1.8 meters to 2.4 or 3.8 meters.
Feed horn is mounted at focal point of the antenna. The feed horn guides transmitted power towards the antenna
2. VSAT Network Overview
DOI: 10.9790/2834-10131824 www.iosrjournals.org 19 | Page
dish and will go to the medium consecutively. It also collects the received power from dish and will enter into
the LNA. Feed horn is made of array of microwave passive components. The outdoor unit is connected through
coaxial cable to the indoor unit, which is situated inside the room/building. Length of the cable is usually about
300 foot (approx. 90 meter).
1.2 vsat indoor unit
The IDU consists of MUX/DEMUX, EDU (Encryption Decryption Unit), modem (modulator-
demodulator). MUX will interface with end user equipments viz. telephone, computers and sometime with
EPABX and LAN or router, if it has to carry more information. MUX will multiplex all the channels connected
with it using TDM. On receiver side DEMUX is used to de-multiplex the channels and passed on to respective
end user equipments. EDU is basically the Encryption-Decryption unit which provides security by modifying
the information to be transmitted. On receiver side encryption technique will be conveyed so that the
information can be retrieved back again. MODEM is basically performs modulator-demodulator functionality
on transmit and receive side respectively. Modulator inserts information on intermediate frequency (IF), usually
called carrier. This is done based on modulation scheme set. Usually QPSK scheme is used in satellite
communication and Forward Error Correction is also employed in modem which enhances the BER for the
same transmitter power usually used in non-FEC systems. In order to communicate between VSAT 1 and VSAT
2, modulator frequency of VSAT 1 and demodulator frequency of VSAT 2 need to be same and vice versa to
complete full duplex communication channel. Based on frequency assignments as per FDMA various modem
and RF frequency converters are set. [4]
Figure (1): components of outdoor and indoor units.
II. VSAT Features
VSAT networks uses very small dish antennas therefore, in order to employ the 6/4 –GHz frequency
band it has to utilize the spread spectrum also called CDMA code division multiple access) technique to reduce
the signal power spectral density. This is due to the interference produced for using the same band as terrestrial
microwave transmission does. Alternatively the 14/12 GHz frequency band may be utilized (if available) which
provide satellite capacity with much more efficiency although as we know, with the rain as old enemy. Star
VSAT network at 2-Mbps are now available using Single Channel Per Carrier (SCPC) access which is provided
by most of the vendors however, occasionally , TDMA (Time division multiple access) technique is also used.
VSAT are connected by radio frequency link via satellite. Those links are radio frequency link with a so-called
uplink from the station to the satellite and so-called downlink from station to station, sometime called hop
consists of an uplink and downlink.
2.1Uplink
A radio frequency link is modulated carrier conveying information. Basically the satellite receives the
uplink carriers from the transmitting earth station within the field of view of its receiving antenna.
2.2Downlink
Within the field of view Transponder amplifies those carriers, translates their frequency to a lower
band in order to avoid possible output/input interference, and transmits the amplified carrier to the station
located of its transmitting antenna. [1]
2.3Vsat frequency band
VSATs operate in the Ku band and C band frequencies. As a rule of thumb C- band (which suffers less
from rain attenuation but requires larger antennas) is used in Asia, Africa and Latin America. Ku-band (which
can use smaller antennas but suffers from rain fade in monsoon like downpour) is used in Europe and North
3. VSAT Network Overview
DOI: 10.9790/2834-10131824 www.iosrjournals.org 20 | Page
America. Interactive antenna sizes range from 75 centimetres to 1.8 meters for Ku-band and C-band from 1.8
meters to 2.4 meters. One way systems can use antennas as small as 45 centimetres. [3]
2.4 Vsat traransmission band
VSATs are most commonly used to transmit:
narrowband data (a channel in which the bandwidth of the message does not significantly exceed the
channel’s coherence bandwidth), typical applications are the transmission of payment transaction
from point of sales, or transmission of data from/to SCADA systems.
broadband data (a channel with wide bandwidth characteristics of a transmission medium and the ability to
transport multiple signals and traffic types simultaneously), typical applications are the provision of satellite
Internet access to remote locations, VoIP or video data transmissions. [6]
III. VSAT Network
A VSAT network consists of three components:
A central hub
A satellite
A virtually unlimited number of VSAT user terminals.
How vsat network work :
The user’s devie is connected to the satellite dish . This transmitter mounted on the satellite dish sends
and receives digital signals to a satellite at the same time. When a client requests data from the Internet, the
client’s VSAT dish transmits a signal to the satellite, which in turn retransmits the signal to a central hub earth
station, which in turn is connected, to the Internet. Data from the Internet to the VSAT dish follows the reverse
path. The hub or earth station manages, controls and monitors the network.VSAT is capable of providing
Broadband services.
The satellite is located in a fixed-point 36,000kms above the surface of the earth. This position is
known as the geostationary orbit. Satellites located at this height orbit the earth at the same speed as the earth
rotates on its own axis. This allows the VSAT earth station equipment to be positioned at the satellite and avoids
the need for the VSAT earth satellite dish to be repositioned once the initial installation has been completed.
The VSAT earth stations are usually made up of an outside mounted satellite dish(approximately 1m in
diameter) and a coaxial wire connection to specially installed electronic boards mounted inside the master
computer. These boards allow signals to be transmitted and received from the satellite dish. Transmissions
between the earth station and the satellite station generally operate in the 12 and 14 Ghz frequency bands.
Because of the high frequencies used high levels of rainfall can attenuate the signals. The design of the
installation is generally engineered to allow for the reductions in the radio signal paths during periods of intense
rainfall. The design of the satellite link is generally to guarantee communications for 99.999% time, which is
equivalent to a loss of signal for about 4 minutes per year. During this trial no outages were recorded as a result
of rainfall. The central satellite hub station allows communications to and from the satellite to connect to the
Internet. The central hub station can be located anywhere within the satellite footprint area. For some of the
larger satellite operators a number of central hub stations are operated at different locations to ensure alternative
telecommunications paths in the event of a failure ofone of the hubs. [2]
Figure (2): VSAT dish .
4. VSAT Network Overview
DOI: 10.9790/2834-10131824 www.iosrjournals.org 21 | Page
3.1 Vsat network Architectures
Any telecommunication services there are three basic implementations services: one-way, split-two-way
(referred to as split-IP sometimes, when referring to internet traffic) and two-way implementation. Further
division of two-way implementation are star and mesh network architectures.
There are two Architectures;
Star: In Star network architecture, all traffic is routed via the main hub station. If a VSAT want to
communicate with another VSAT, they have to go through the hub station. This makes double hop link via
the satellite. [4]
Star is The most common VSAT configuration os the TDM/TDMA. These have a high bit rate
outbound carrier (Time Division Multiplexed) from the hub to the remote earth stations, and one or more low or
medium bit rate (Time Division Multiple Access) inbound carriers. In a typical VSAT network, remote users
have a number of personal computers or dumb terminals that are connected to the VSAT terminal that in turn is
connected to a centralised host computer either at individual sites or at a data processing centre. Data sent to the
VSAT terminal from the data terminal equipment (DTEs) is buffered and transmitted to the hub in packets. [5]
Figure(3): star vesat tepology. [6.]
Mesh: Meshed VSAT networks provide a way to set up a switched point to point data network that can
have the capability for high data rates of up to 2Mb/s. Links are set up directly between remote terminals
usually on a call by call basis. These networks are usually configured to operate without a large central
earth station and carry a mix of data traffic and telephony traffic or only data traffic. These networks
generally will have a network control station, which controls the allocation of resources across the network.
This control centre is only involved in the signalling for the call setup/teardown and in monitoring the
operation of the network. [5]
Figure (4) : mesh vsat topology. [6]
There are three factors that’s shows wich architectures sutable than others one:
■ The structure of information flow within the network.
■ The requested link quality and capacity.
■ The transmission delay.
Structure of Information Flow
VSAT network can support different type of application and each has an optimum network
configuration.
5. VSAT Network Overview
DOI: 10.9790/2834-10131824 www.iosrjournals.org 22 | Page
Broadcasting: A central site distributes information to many remote sites with no back flow of
information. Hence a start shaped one-way network supports the service at the lowest cost.
Corporate Network: Most often companies have a centralized structure with administration and
management performed at a central site, and manufacturing or sales performed at site scattered over a
geographical area information from the remote sites needs to be gathered at the central site has to be distributed
to the remote ones, such as task sharing. Such an information flow can be partially supported by a start one-way
VSAT Network.
Interactivity Between Distributed Sites: Other companies or organization with decentralised structure
are more likely to compromise many interacting one with a meshed VSAT network using direct single hop
connections from VSAT to VSAT is hence mostly desirable.
Link Quality and Capacity
The link considered here is the link from the transmitting to the receiving one. Such a link may
comprise several parts. For instance a single hop link would comprise an uplink and downlink; a double hop
link would comprise two single hop links, one being inbound and outbound. Fig 1.3 indicates the general trend
which relates EIRP to G/T in a VSAR network, considering a given baseband signal quality in term of constant
BER. EIRP designates the equivalent isotropic radiated power of the transmitting equipment and G/T is the
figure of merit of the receiving equipment.
Transmission Delay
With a single hop link from VSAT in a humbles network, the propagation delay is about 0.25s. With a
double hop from VSAT to VSAT via the hub, the propagation delay is twice as much, i.e. about 0.5s.
Double hop may be a problem for voice communication. However, it is not a severe problem for video or data
transmission. Table 1.2 summarizes the above discussion given the EIRP and G/T values for a VSAT, the
designer can decide for both a large delay from VSAT to VSAT and a large capacity or a small delay and a
lower capacity, by implementing either a start network, or mesh one.
Table1:Characteristics of star and mesh network configuration. [1]
3.2 Flexibility of vsat network
One of the main advantages of VSAT networks is that network expansion, addition of new terminals
and provision of new services can be accommodated without reconfiguring or impacting the operation of the
rest of the network.
However, the performance of the network and hence the quality of the service delivered to the user are
sensitive to the amount of traffic, which increases as more and more terminals of VSATs are added to the
network. It is therefore important to allow spare capacity in the space segment and the hub, typically 20% more
traffic and 20% more VSATs than initially expected. Growth beyond initial capacity must be orderly and
modular. Considering that frequent acquisitions and corporate restructuring are part of today’s business world, it
is important that the customer not be constrained on its potential growth in telecommunication needs.
3.3 Vsat network application and types of traffic
3.3.1 Civilian VSAT networks
Types of service
VSAT networks deal with interactive data traffic, where the user terminals are most often personal
computers. The most notable exceptions are voice communications and satellite news gathering. Voice
communications on a VSAT network means telephony with possibly longer delays than those incurred on
terrestrial lines, as a result of the long satellite path. Telephony services imply full connectivity, and delays are
typically 0.25 s or 0.50 s depending on the selected network configuration, as mentioned above.
Satellite news gathering (SNG) can be viewed as a temporary network using transportable VSATs,
sometimes called ‘fly-away’ stations, which are transported by car or aircraft and set up at a location where
news reporters can transmit video signals to a hub
Types of traffic
Depending on the service, the traffic flow between the hub and theVSATs may have different
characteristics and requirements.
6. VSAT Network Overview
DOI: 10.9790/2834-10131824 www.iosrjournals.org 23 | Page
Data transfer or broadcasting ,which belongs to the category of oneway services, typically displays file
transfers of one to one hundred megabytes of data. This kind of service is not delay sensitive, but requires a high
integrity of the data which are transferred. Examples of applications are computer download and distribution of
data to remote sites.
Interactive data, is a two-way service corresponding to several transactions per minute and per terminal
of single packets 50 to 250 bytes long on both inbound and outbound links. The required response time is
typically a few seconds. Examples of applications are bank transactions and electronic funds transfer at point of
sale.
Inquiry/responsais a two-way service corresponding to several transactions per minute and terminal.
Inbound packets (typically 30–100 bytes) are shorter than outbound packets (typically 500–2000 bytes). The
required response time is typically a few seconds.
Examples of applications are airline or hotel reservations and database enquiries.
Supervisory control and data acquisition (SCADA) is a two-way service corresponding to one
transaction per second or minute per terminal. Inbound packets (typically 100 bytes) are longer than outbound
packets (typically 10 bytes). The required response time ranges from a few seconds to a few minutes. What is
most important is the high data security level and the low power consumption of the terminal. Examples of
applications are control and monitoring of pipelines, offshore platforms, electric utilities and water resources.
3.3.2 Military VSAT Network
Military forces in the world have adopted VSAT networks indeed the inherent flexibility in the
deployment of VSAT s makes them a valuable means to install temporary communication link between small
units in the battlefield and headquarters located near the hub. More over the topology of a star shaped network
fits well into the natural information flow between field units and command base. Frequency bands are at X-
band, with uplinks in the 7.9-8.4 GHz band and downlinks in the 7.25-7.75 GHz bands. [3]
3.4 Vsat network security
VSAT network terminal Susceptible for many haching types that is may Adversely affect or stop work
of the network.
Most common hacking:
Firstly, what we typically see in the field is automated port scans. Where individuals or programs operating
in the internet will scan the ports of all IP addresses in certain IP ranges, including VSAT terminals, and
depending on the ports, try to log in. With this we see a massive flood of TCP connections and IP ping
messages to terminals and any device behind those terminals. Generally, when logging in does not succeed
they hop to the next IP address. They just scan the entire internet and when they are not successful, they just
move on.
Secondly, VSAT terminals typically offer more services than pure IP routing, like some HTTP webservers
or file sharing services. The next step in hacking a terminal is trying to exploit the vulnerabilities of these
services on the terminal. This is typically done by exploiting buffer overruns in the software
implementation of these services. When successful, the hacker is typically able to force the device to run
any type of malicious software.
Thirdly, hackers may opt to use low-end routers or terminals as a distributer for viruses. Since these devices
are always powered on and people don’t distrust their own devices, infected devices can cause a rapid
spread of viruses in the local network.
Fourthly, in case there is a network behind your terminal which is publicly accessible (e.g. a library).
Someone can try to hack the VSAT terminal from within this public network with any of the above
methods, often just to display their hacking skills.
Once access is gained to the terminal, it can be used for snooping any passing internet traffic, for
example stealing credit card data or passwords. Normally no information itself is stored on the VSAT terminal,
but it can be intercepted on the terminal.
3.4.1Securing visat terminal
It is possible to protect VSAT terminals by not allowing them direct connectivity to the internet. You
can remotely connect to the VSAT terminal, but only if you pass by the VSAT hub, using the hub as an
intermediate hop. If you set your network up in this way there is no direct connectivity between the terminal and
the internet. Thisprotects against the bulk of the first three types of hacking. Note that blocking connectivity
between the terminal and the internet does not in any way impact the client’s ability to use the VSAT terminal
for bidirectional internet access.
7. VSAT Network Overview
DOI: 10.9790/2834-10131824 www.iosrjournals.org 24 | Page
The second and fourth types of hacking consist of exploiting open ports to login typically using Telnet
or SSH. The approach taken on our, Newtec’s, VSAT terminals is to make sure that none of the terminal’s ports
are accessible from the internet and alimited set of ports (i.e. HTTP, DNS, DHCP, etc.) can be accessed from the
customer premises network. Moreover, the services that are accessible from the customer premises network
have limited system access. So even if a service is hacked, there is another barrier to overcome before any data
can be accessed and/or intercepted.
You can also protect the devices in the customer premises network by filtering, blocking or
detecting that they are undergoing a hacking attempt. Protecting these devices is generally not done by the
manufacturer of the VSAT equipment, but it is up to the clients to do so. This is typically done just before the
VSAT hub where you can implement some sort of blocking policy.
Finally, it is also important to secure the satellite communication link. Sensitive data could be
intercepted between the terminals and the hub, since satellite communication is distributed.
3.4.2 Securing the communication link
Over large geographical areas, meaning that almost anyone can listen in. To prevent this from
happening, the approach taken by Newtec (and others) is to encrypt all user data that is flowing via the VSAT
link. This is done by separating all user data immediately when it enters the VSAT terminal and isolate the
traffic inside an encrypted tunnel.
Another threat to the satellite communication link is a rogue VSAT terminal taking over the satellite
link of another VSAT terminal. This would offer a malicious user unauthorised access to the network. To
counter this, your VSAT terminal (like theMDM2200 – see picture) can add a X.509 certificate based
authentication to its encryption key exchange protocol. This creates a strong tie between the intended VSAT
terminal and the satellite link and as such prevents rogue VSAT terminals accessing your network. [8]
IV. Conclusion
Vsat technology it is two way communication via satellite that allows to service providers offers fast
and secure transmission. The main advantages of VSAT systems are their flexibility and ease of installation.
The established terrestrial network is certain to expand its coverage progressively, and in fixed configurations
between large population centres it will provide the most efficient means of communications.
Vsat network can be secure against of the different five types of hacking by securing the vsat terminals and vsat
communication link.
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[3]. September 2003
[4]. John Wiley & Sons Ltd, :Vsat Network" The Atrium, Southern Gate, Chichester, West Sussex Po19 8sq, England 1995 & 2003
[5]. Http://Samples.Sainsburysebooks.Co.Uk/9780470866856_Sample_383472.Pdf
[6]. Http://Www.Academia.Edu/8591677/Vsat_System_Overview_Covering_Block_Schematic_Installation_And_More
[7]. Http://Services.Eng.Uts.Edu.Au/~Kumbes/Ra/Wireless_Networks/Vsat/Trevs%20page/Vsat.Htm
[8]. Http://Securityaffairs.Co/Wordpress/21049/Hacking/Vsat-Terminals-Opened-Targeted-Cyber-Attacks.Html
Http://Www.Level421.Com/Index.Php?Id=1730
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