The document discusses concepts and models of computer communication. It defines the basic components of a communication system including the source, transmitter, transmission system, receiver, and destination. It also discusses transmission media, data representation, parallel vs serial transmission, and asynchronous transmission. The key aspects are models for computer communication, basic communication components, and differences between parallel and serial transmission.
Transmission media (data communication)Pritom Chaki
Transmission media is the material pathway that connects computers, different kinds of devices and people on a network. It can be compared to a superhighway carrying lots of information. Transmission media uses cables or electromagnetic signals to transmit data.
Computer Networks Unit 1 Introduction and Physical Layer Dr. SELVAGANESAN S
This document discusses data communication and computer networks. It defines data communication as the exchange of data between devices via transmission medium. A data communication system has five components: sender, receiver, message, medium, and protocol. Communication can be simplex, half-duplex, or full-duplex. The document also defines networks, explaining that a network allows interconnected devices to communicate and share resources. Local area networks (LANs), metropolitan area networks (MANs), and wide area networks (WANs) are described as the main categories of networks.
Communication protocols define the rules for transmitting data over a network. They provide an orderly method for exchanging data between sender and receiver. The document then describes the key roles of communication protocols such as data sequencing, routing, formatting, flow control, error control, transmission order, and connection establishment/termination. It also summarizes the OSI model which outlines 7 layers that interact to send data between computers, and describes what each layer is responsible for.
This document provides an overview of the Open Systems Interconnection (OSI) model, which defines seven layers of network communication. It describes each layer's functions and responsibilities, including the physical layer for transmitting bits, the data link layer for framing and addressing, the network layer for routing packets, the transport layer for process-to-process delivery, the session layer for dialog control, the presentation layer for data translation, and the application layer for user interfaces and services. The OSI model was designed by ISO in the late 1970s to provide a standard framework for network protocol implementation across different systems.
This document provides an introduction to data communications and networks. It discusses key topics such as data representation, data flow, characteristics of data communication like delivery and accuracy. It describes different network types including LAN, WAN, MAN. Network topologies like star, bus, ring and hybrid are explained. Protocols define rules for communication regarding what, how and when to communicate. Standards are agreed upon rules and are developed by standards organizations.
The document discusses network models and addressing in computer networks. It introduces the OSI model, which defines seven layers of network functionality. Each layer has a specific role, such as the physical layer dealing with bit transmission and the application layer providing services to users. The document also discusses the TCP/IP protocol suite and how it maps to the OSI layers. Finally, it covers the different types of addresses used in TCP/IP networks, including physical, logical, port, and specific addresses.
This document discusses different types of transmission media used for data communication. It describes guided media such as twisted pair cables, coaxial cables, and fiber optic cables. It also covers unguided or wireless media such as radio waves, microwaves, and infrared. For each medium, it provides details on their characteristics, applications, advantages and disadvantages. The document aims to classify and explain the basic concepts of different transmission media and their use in data communication networks.
This document discusses local area networks (LANs) and the use of fiber optic cables in LAN architecture. It describes different LAN topologies including bus, ring, star and their implementations. It compares fiber optic cables favorably to copper cables, noting fiber's higher bandwidth, reliability and longer transmission distances. The document also discusses specific ring-based standards like FDDI that use fiber optic cables to interconnect lower-speed LANs or mainframe computers at speeds up to 100 Mbps. Overall, the document promotes the use of fiber optic cables in LANs for their benefits over copper in supporting growing bandwidth demands.
Transmission media (data communication)Pritom Chaki
Transmission media is the material pathway that connects computers, different kinds of devices and people on a network. It can be compared to a superhighway carrying lots of information. Transmission media uses cables or electromagnetic signals to transmit data.
Computer Networks Unit 1 Introduction and Physical Layer Dr. SELVAGANESAN S
This document discusses data communication and computer networks. It defines data communication as the exchange of data between devices via transmission medium. A data communication system has five components: sender, receiver, message, medium, and protocol. Communication can be simplex, half-duplex, or full-duplex. The document also defines networks, explaining that a network allows interconnected devices to communicate and share resources. Local area networks (LANs), metropolitan area networks (MANs), and wide area networks (WANs) are described as the main categories of networks.
Communication protocols define the rules for transmitting data over a network. They provide an orderly method for exchanging data between sender and receiver. The document then describes the key roles of communication protocols such as data sequencing, routing, formatting, flow control, error control, transmission order, and connection establishment/termination. It also summarizes the OSI model which outlines 7 layers that interact to send data between computers, and describes what each layer is responsible for.
This document provides an overview of the Open Systems Interconnection (OSI) model, which defines seven layers of network communication. It describes each layer's functions and responsibilities, including the physical layer for transmitting bits, the data link layer for framing and addressing, the network layer for routing packets, the transport layer for process-to-process delivery, the session layer for dialog control, the presentation layer for data translation, and the application layer for user interfaces and services. The OSI model was designed by ISO in the late 1970s to provide a standard framework for network protocol implementation across different systems.
This document provides an introduction to data communications and networks. It discusses key topics such as data representation, data flow, characteristics of data communication like delivery and accuracy. It describes different network types including LAN, WAN, MAN. Network topologies like star, bus, ring and hybrid are explained. Protocols define rules for communication regarding what, how and when to communicate. Standards are agreed upon rules and are developed by standards organizations.
The document discusses network models and addressing in computer networks. It introduces the OSI model, which defines seven layers of network functionality. Each layer has a specific role, such as the physical layer dealing with bit transmission and the application layer providing services to users. The document also discusses the TCP/IP protocol suite and how it maps to the OSI layers. Finally, it covers the different types of addresses used in TCP/IP networks, including physical, logical, port, and specific addresses.
This document discusses different types of transmission media used for data communication. It describes guided media such as twisted pair cables, coaxial cables, and fiber optic cables. It also covers unguided or wireless media such as radio waves, microwaves, and infrared. For each medium, it provides details on their characteristics, applications, advantages and disadvantages. The document aims to classify and explain the basic concepts of different transmission media and their use in data communication networks.
This document discusses local area networks (LANs) and the use of fiber optic cables in LAN architecture. It describes different LAN topologies including bus, ring, star and their implementations. It compares fiber optic cables favorably to copper cables, noting fiber's higher bandwidth, reliability and longer transmission distances. The document also discusses specific ring-based standards like FDDI that use fiber optic cables to interconnect lower-speed LANs or mainframe computers at speeds up to 100 Mbps. Overall, the document promotes the use of fiber optic cables in LANs for their benefits over copper in supporting growing bandwidth demands.
Network devices such as repeaters, bridges, switches and routers are used to connect and expand networks. Repeaters regenerate signals to expand small networks, while bridges and switches can understand node addresses to segment networks. Routers interconnect different networks and determine optimal routes using network layer addresses and routing protocols. Remote access devices like modems and ADSL modems allow computers to connect to networks over telephone lines by modulating digital signals into analog for transmission.
Ethernet is the most widely used local area network technology. It was originally developed by Xerox and later standardized. Ethernet networks can operate at speeds of 10 Mbps, 100 Mbps, 1 Gbps, or 10 Gbps using different cabling standards. Faster standards were developed to meet increasing needs for higher transmission speeds and applications like multimedia. Token Ring is another common LAN protocol that uses a token-passing scheme to prevent collisions. It provides data transfer rates of 4 or 16 Mbps. Fiber Channel is a standard for very high speed data transfers of up to 1 Gbps primarily used to connect storage devices.
This document discusses various topics related to data transmission including:
- Data transmission involves transferring electromagnetic signals over a physical communication channel like copper wires or wireless channels.
- Transmission modes can be parallel (multiple bits sent at once) or serial (one bit at a time). Serial transmission is further divided into asynchronous and synchronous types.
- Asynchronous transmission groups data into start-stop bit sequences while synchronous transmission uses device-generated clocks for synchronization.
Reference models in Networks: OSI & TCP/IPMukesh Chinta
The document discusses reference models and the OSI reference model. It provides details on:
- The need for a reference model to standardize network components and layer functions to promote interoperability.
- The OSI reference model, approved in 1984, which divides communication problems into seven layers to aid in network interconnection.
- Each of the seven layers of the OSI model, describing their functions and responsibilities for moving data through the network.
The document describes the seven-layer OSI model, with each layer responsible for certain network functions. The physical layer transmits raw bits over a transmission medium. The data link layer transmits frames between nodes. The network layer delivers packets from source to destination hosts via routing. The transport layer provides reliable process-to-process message delivery. The session layer establishes and manages communication sessions. The presentation layer handles translation and formatting. The application layer provides services to the user/application.
This document discusses and compares wired and wireless networks. Wired networks transmit data through physical cables connecting devices, while wireless networks transmit data through the air using electromagnetic waves without cables. Examples of wired networks include telephone lines, cable TV, and fiber optic networks, while wireless technologies include radio frequencies, infrared, Bluetooth, Wi-Fi, and satellite communication.
S.VIJAYALAKSHMI M.SC(CS) discusses Media Access Control and multiple access protocols. The main task of MAC protocols is to minimize collisions and utilize bandwidth by determining when nodes can access the shared channel, what to do when the channel is busy, and how to handle collisions. Early protocols like Aloha and slotted Aloha were inefficient at high loads due to many collisions. CSMA protocols reduce collisions by having nodes listen first before transmitting, but collisions are still possible due to propagation delays.
This document provides an overview of data communication systems and computer networks. It discusses the key components of a data communication system including the message, sender, receiver, transmission medium, and protocols. It then describes different data transmission modes such as simplex, half-duplex, and full-duplex. The document also covers computer network types including LANs, MANs, and WANs, as well as network topologies like mesh, star, bus, and ring configurations. Finally, it discusses some common uses of computer networks for businesses and homes.
Attenuation, distortion, and noise are the main causes of transmission impairments. Attenuation is the reduction of signal strength during transmission, distortion alters the original signal shape, and noise is random electrical interference from internal and external sources that disrupts signal reception. These transmission impairments degrade, weaken, and contaminate signals as they travel through transmission mediums.
This document provides an overview of data link control (DLC) and data link layer protocols. It discusses the key functions of DLC including framing, flow control, and error control. Framing involves encapsulating data frames with header information like source and destination addresses. Flow control manages the flow of data between nodes while error control handles detecting and correcting errors. Common data link layer protocols described include simple protocol, stop-and-wait protocol, and High-Level Data Link Control (HDLC). HDLC is a bit-oriented protocol that supports full-duplex communication over both point-to-point and multipoint links. It uses three types of frames: unnumbered, information, and supervisory frames.
Unicast involves sending data from one computer to another, with one sender and one receiver. Multicast sends data to a group of devices that have joined the multicast group, with one sender but multiple potential receivers. Broadcast sends data from one computer that is then forwarded to all connected devices, with one sender and all devices receiving the broadcast traffic.
Unguided media, also known as wireless media, transmit data through space without the use of wires or cables. This includes transmission via radio waves, microwaves, and infrared waves. Radio waves are used for WiFi, mobile phones, remote controls, television broadcasts, and more. Modulation involves varying properties of a signal, and can be analog, transferring signals like audio, or digital, transferring bit streams. Infrared waves are used for short-range communication like night vision cameras, remote controls, and file sharing between devices that require a direct line of sight.
TCP/IP is a set of communication protocols that enable data transmission across networks and between devices. It involves two main protocols: TCP and IP. TCP establishes reliable connections and ensures reliable delivery of data packets. IP handles addressing, routing packets between networks, and fragmentation/reassembly of packets. Key features of TCP/IP include logical addressing, routability, name resolution, multiplexing, and interoperability. TCP/IP operates on four layers - network interface, internet, transport, and application - with each layer building on the services of the layer below.
The document discusses the session layer in the OSI model. It begins by explaining why layered architectures were developed and providing an overview of the OSI model and its seven layers. It then focuses on the session layer, describing its main purpose of establishing, maintaining, and synchronizing interactions between communicating systems. Key functions of the session layer are establishing connections, negotiating session parameters, and managing data transfer phases. Several common session layer protocols are also listed.
Asynchronous Transfer Mode (ATM) is a cell-based switching and multiplexing technology that was designed in the early 1990s to expedite the transmission of voice, video, and data over digital networks. ATM uses fixed-length cells of 53 bytes to carry traffic. It establishes virtual connections between endpoints to guarantee quality of service. ATM works by segmenting data into fixed-size cells at the source, transporting cells through a switch network via virtual circuits, and reassembling them at the destination. It provides benefits like high performance, integration of multiple data types, and adaptability to different network speeds.
This document provides information about error detection and correction techniques used in computer networks. It discusses different types of errors that can occur like single-bit and burst errors. It explains that redundancy is needed to detect or correct errors by adding extra bits. Detection techniques discussed include parity checks, checksumming, and cyclic redundancy checks. Parity checks can only detect odd number of errors. Cyclic redundancy checks use polynomial arithmetic to generate a checksum. Forward error correction allows detection and correction of errors by adding redundant bits to distinguish different error possibilities. Hamming code is an example of an error correcting code that can detect and correct single bit errors.
This document provides an overview of data communications and computer networks. It discusses the fundamental problem of communication and reproducing messages at different points. It also describes trends in traffic growth and new services, and reviews the components of a basic communications model. Additionally, it examines different types of networks including local area networks, wide area networks, and the Internet—covering technologies like circuit switching, packet switching, frame relay, and asynchronous transfer mode. The chapter introduces concepts like transmission media, networking, and elements that make up modern network architectures.
The document discusses serial communications and common interface standards. It covers:
1) Types of serial communication including asynchronous and synchronous transfer, and simplex, half duplex, and full duplex transfer types.
2) The RS-232 standard for serial communication interfaces between DTE and DCE devices. It specifies voltage levels, connector types, and signal functions.
3) Common interface chips like the 8250/16450/16550 UART used for asynchronous communication and flow control between devices.
Network devices such as repeaters, bridges, switches and routers are used to connect and expand networks. Repeaters regenerate signals to expand small networks, while bridges and switches can understand node addresses to segment networks. Routers interconnect different networks and determine optimal routes using network layer addresses and routing protocols. Remote access devices like modems and ADSL modems allow computers to connect to networks over telephone lines by modulating digital signals into analog for transmission.
Ethernet is the most widely used local area network technology. It was originally developed by Xerox and later standardized. Ethernet networks can operate at speeds of 10 Mbps, 100 Mbps, 1 Gbps, or 10 Gbps using different cabling standards. Faster standards were developed to meet increasing needs for higher transmission speeds and applications like multimedia. Token Ring is another common LAN protocol that uses a token-passing scheme to prevent collisions. It provides data transfer rates of 4 or 16 Mbps. Fiber Channel is a standard for very high speed data transfers of up to 1 Gbps primarily used to connect storage devices.
This document discusses various topics related to data transmission including:
- Data transmission involves transferring electromagnetic signals over a physical communication channel like copper wires or wireless channels.
- Transmission modes can be parallel (multiple bits sent at once) or serial (one bit at a time). Serial transmission is further divided into asynchronous and synchronous types.
- Asynchronous transmission groups data into start-stop bit sequences while synchronous transmission uses device-generated clocks for synchronization.
Reference models in Networks: OSI & TCP/IPMukesh Chinta
The document discusses reference models and the OSI reference model. It provides details on:
- The need for a reference model to standardize network components and layer functions to promote interoperability.
- The OSI reference model, approved in 1984, which divides communication problems into seven layers to aid in network interconnection.
- Each of the seven layers of the OSI model, describing their functions and responsibilities for moving data through the network.
The document describes the seven-layer OSI model, with each layer responsible for certain network functions. The physical layer transmits raw bits over a transmission medium. The data link layer transmits frames between nodes. The network layer delivers packets from source to destination hosts via routing. The transport layer provides reliable process-to-process message delivery. The session layer establishes and manages communication sessions. The presentation layer handles translation and formatting. The application layer provides services to the user/application.
This document discusses and compares wired and wireless networks. Wired networks transmit data through physical cables connecting devices, while wireless networks transmit data through the air using electromagnetic waves without cables. Examples of wired networks include telephone lines, cable TV, and fiber optic networks, while wireless technologies include radio frequencies, infrared, Bluetooth, Wi-Fi, and satellite communication.
S.VIJAYALAKSHMI M.SC(CS) discusses Media Access Control and multiple access protocols. The main task of MAC protocols is to minimize collisions and utilize bandwidth by determining when nodes can access the shared channel, what to do when the channel is busy, and how to handle collisions. Early protocols like Aloha and slotted Aloha were inefficient at high loads due to many collisions. CSMA protocols reduce collisions by having nodes listen first before transmitting, but collisions are still possible due to propagation delays.
This document provides an overview of data communication systems and computer networks. It discusses the key components of a data communication system including the message, sender, receiver, transmission medium, and protocols. It then describes different data transmission modes such as simplex, half-duplex, and full-duplex. The document also covers computer network types including LANs, MANs, and WANs, as well as network topologies like mesh, star, bus, and ring configurations. Finally, it discusses some common uses of computer networks for businesses and homes.
Attenuation, distortion, and noise are the main causes of transmission impairments. Attenuation is the reduction of signal strength during transmission, distortion alters the original signal shape, and noise is random electrical interference from internal and external sources that disrupts signal reception. These transmission impairments degrade, weaken, and contaminate signals as they travel through transmission mediums.
This document provides an overview of data link control (DLC) and data link layer protocols. It discusses the key functions of DLC including framing, flow control, and error control. Framing involves encapsulating data frames with header information like source and destination addresses. Flow control manages the flow of data between nodes while error control handles detecting and correcting errors. Common data link layer protocols described include simple protocol, stop-and-wait protocol, and High-Level Data Link Control (HDLC). HDLC is a bit-oriented protocol that supports full-duplex communication over both point-to-point and multipoint links. It uses three types of frames: unnumbered, information, and supervisory frames.
Unicast involves sending data from one computer to another, with one sender and one receiver. Multicast sends data to a group of devices that have joined the multicast group, with one sender but multiple potential receivers. Broadcast sends data from one computer that is then forwarded to all connected devices, with one sender and all devices receiving the broadcast traffic.
Unguided media, also known as wireless media, transmit data through space without the use of wires or cables. This includes transmission via radio waves, microwaves, and infrared waves. Radio waves are used for WiFi, mobile phones, remote controls, television broadcasts, and more. Modulation involves varying properties of a signal, and can be analog, transferring signals like audio, or digital, transferring bit streams. Infrared waves are used for short-range communication like night vision cameras, remote controls, and file sharing between devices that require a direct line of sight.
TCP/IP is a set of communication protocols that enable data transmission across networks and between devices. It involves two main protocols: TCP and IP. TCP establishes reliable connections and ensures reliable delivery of data packets. IP handles addressing, routing packets between networks, and fragmentation/reassembly of packets. Key features of TCP/IP include logical addressing, routability, name resolution, multiplexing, and interoperability. TCP/IP operates on four layers - network interface, internet, transport, and application - with each layer building on the services of the layer below.
The document discusses the session layer in the OSI model. It begins by explaining why layered architectures were developed and providing an overview of the OSI model and its seven layers. It then focuses on the session layer, describing its main purpose of establishing, maintaining, and synchronizing interactions between communicating systems. Key functions of the session layer are establishing connections, negotiating session parameters, and managing data transfer phases. Several common session layer protocols are also listed.
Asynchronous Transfer Mode (ATM) is a cell-based switching and multiplexing technology that was designed in the early 1990s to expedite the transmission of voice, video, and data over digital networks. ATM uses fixed-length cells of 53 bytes to carry traffic. It establishes virtual connections between endpoints to guarantee quality of service. ATM works by segmenting data into fixed-size cells at the source, transporting cells through a switch network via virtual circuits, and reassembling them at the destination. It provides benefits like high performance, integration of multiple data types, and adaptability to different network speeds.
This document provides information about error detection and correction techniques used in computer networks. It discusses different types of errors that can occur like single-bit and burst errors. It explains that redundancy is needed to detect or correct errors by adding extra bits. Detection techniques discussed include parity checks, checksumming, and cyclic redundancy checks. Parity checks can only detect odd number of errors. Cyclic redundancy checks use polynomial arithmetic to generate a checksum. Forward error correction allows detection and correction of errors by adding redundant bits to distinguish different error possibilities. Hamming code is an example of an error correcting code that can detect and correct single bit errors.
This document provides an overview of data communications and computer networks. It discusses the fundamental problem of communication and reproducing messages at different points. It also describes trends in traffic growth and new services, and reviews the components of a basic communications model. Additionally, it examines different types of networks including local area networks, wide area networks, and the Internet—covering technologies like circuit switching, packet switching, frame relay, and asynchronous transfer mode. The chapter introduces concepts like transmission media, networking, and elements that make up modern network architectures.
The document discusses serial communications and common interface standards. It covers:
1) Types of serial communication including asynchronous and synchronous transfer, and simplex, half duplex, and full duplex transfer types.
2) The RS-232 standard for serial communication interfaces between DTE and DCE devices. It specifies voltage levels, connector types, and signal functions.
3) Common interface chips like the 8250/16450/16550 UART used for asynchronous communication and flow control between devices.
The document discusses peripherals and interfacing, specifically focusing on interfacing an I/O device like a keyboard to an 8051 microcontroller. It provides details on how the keyboard is organized in a matrix with rows and columns connected to microcontroller ports. It describes the process of scanning the rows and columns to detect key presses and identify the specific key. It includes circuit diagrams and explanations of interfacing the keyboard and displaying the pressed key on a 7-segment display.
1. An interrupt is an event that informs the CPU to pause its current task and service the pending interrupt request. Common sources include internal errors, external hardware devices, and software interrupts.
2. When an interrupt occurs, the CPU saves its state, reads the interrupt service routine address, executes the ISR, restores its state and returns to the original task.
3. The 8259 PIC (Programmable Interrupt Controller) manages interrupt requests from external devices, allowing prioritization and masking of interrupts.
INTRODUCTION TO BASICS OF DATA COMMUNICATION"Sfakz133
This document summarizes key concepts in data and computer communications:
1) A communications model outlines the basic process of data transmission from a source, through a transmitter, transmission system, receiver, and to a destination, with tasks like flow control, error detection, and routing.
2) Networking allows connection of devices that are too far apart for direct point-to-point communication, through local area networks within buildings and wide area networks across large geographical areas.
3) Wide area networks rely on circuit switching, packet switching, and transmission technologies like frame relay and asynchronous transfer mode to connect distant locations.
Data models can facilitate communication between designers, programmers, and users. A well-developed data model can improve understanding of an organization. Data models are a communication tool that represent different types of relationships in a database. Common data models include hierarchical, network, relational, entity-relationship, and object-oriented models. Each model has advantages like conceptual simplicity and flexibility as well as disadvantages like complexity and implementation limitations.
The document discusses various topics related to digital transmission including:
1. Digital-to-digital conversion techniques like line coding, block coding, and scrambling that are used to represent digital data with digital signals. Line coding is always needed while block coding and scrambling may or may not be needed.
2. Analog-to-digital conversion techniques like pulse code modulation (PCM) and delta modulation that are used to convert analog signals to digital data. PCM involves sampling, quantization, and encoding of analog signals.
3. Transmission modes including parallel transmission of multiple bits together and serial transmission of one bit at a time. Serial transmission can be asynchronous, synchronous, or isochronous depending
Data communication and network Chapter -1Zafar Ayub
This document discusses data communication and networks. It defines data communication as the electronic transmission of digitally encoded information between networks via a medium. A network is defined as hardware, software, and protocols that allow sharing of resources and information according to set rules. The document also defines several key terms related to data communication and networks such as data, resources, channels, protocols, encryption, network hardware and software, senders, and receivers. It describes methods of data transmission including serial and parallel transmission.
The document discusses communication systems and their key components and concepts. It defines analog and digital signals, and the advantages and disadvantages of each. It explains the basic elements of a communication system, including the information source, transmitter, channel, and receiver. It also discusses different types of transmission such as simplex, full duplex, and half duplex. Modulation is introduced as a key concept for transmitting baseband signals over long distances.
This document provides an overview of data communication basics including:
- The components of a data communication system including the message, sender, receiver, transmission medium, and protocols.
- Characteristics of effective data transmission including delivery, accuracy, timeliness, and jitter.
- Types of data transmission including parallel, serial, asynchronous, and synchronous.
- Factors that can impair transmission such as attenuation, distortion, and noise. Errors can occur due to equipment failure, dispersion, attenuation, or thermal noise.
This document provides an overview of wireless communications and mobile computing. It begins with definitions of communication, telecommunications, and the basic components and models of communication systems. It then discusses wireless transmission media like radio waves, microwaves, and infrared. The document outlines the history of wireless technologies from early systems like radio to modern cellular standards. It also describes different types of wireless services including broadcast, paging, cellular telephony, trunking radio, cordless telephony, and wireless local area networks.
Data communication : entails electronically exchanging data or information. It is the movement of computer information from one point to another by means of electrical or optical transmission system. This system often is called data communication networks.
1. Data communication involves the exchange of data between devices via transmission media like wired or wireless networks. It requires both hardware and software to effectively transmit information.
2. For data communication to be effective, it must reliably deliver data to the intended destination, transmit the data accurately, and deliver it in a timely manner. Data representation techniques encode different types of information like text, numbers, images, audio, and video into bit patterns for transmission.
3. Data transmission can be done either serially, transmitting bits one at a time, or in parallel, transmitting multiple bits simultaneously using multiple wires or frequencies. Both methods have advantages and disadvantages depending on the communication needs. Noise, attenuation, and distortion are common transmission impairments
This document provides an introduction to communication systems. It defines a communication system as a system that transfers information from one place to another. Communication systems have various components including a source that generates a message, a transmitter that converts the message to a signal, a channel that conveys the signal, a receiver that converts the signal back to a message, and a destination. Communication systems can transfer both analog and digital signals and messages. Key aspects of communication systems discussed include modulation, encoding, bandwidth, and the tradeoff between communication resources and system performance.
This document discusses various concepts related to communication systems, including:
- The basic elements of a communication system are a transmitter that converts a signal, a channel or medium for transmission, and a receiver that converts the signal back. Noise can interfere with the transmitted information.
- Types of communication include one-way or two-way, analog or digital signals, and baseband or modulated signals. Serial and parallel transmission methods are also covered.
- Key concepts discussed include bandwidth, data rate, baud rate, Nyquist theorem, signal-to-noise ratio, error handling codes, Shannon's theorem, and the electromagnetic spectrum. Noise sources and types are also defined.
This document provides an overview of data communication and computer networks. It discusses:
- The key components of a data communication system including the message, sender, receiver, transmission medium, and protocols.
- Types of data transmission including parallel, serial, synchronous, asynchronous, analog, and digital.
- Network devices like hubs, switches, repeaters, and bridges and their functions in connecting and transmitting data in a network.
- Challenges of data transmission including attenuation, distortion, noise, and their solutions.
This document discusses various methods for compressing analog and digital data. It begins by explaining why analog signals are modulated, such as to allow for more efficient transmission. It then covers analog to digital conversion techniques like pulse code modulation (PCM). On the digital side, it discusses lossless compression methods like run-length encoding, Huffman encoding, and Lempel-Ziv encoding. Lossy compression techniques like JPEG and MPEG are also summarized. The document aims to provide an overview of different data compression strategies.
CND_22634_UNIT1_MSBTE_Computer network and Data CommunicationPranoti Doke
1.1 Data communication and its
characteristics
1.2 Components of data communication Transmitter, Receiver, Medium, Message, Protocol. Standards, Standard organizations. Basic block diagram of data communication system
1.3 Data Transmission: Serial, Parallel Synchronous, Asynchronous, Isochronous transmission
1.4 Transmission characteristics: Signaling rate, data rate, bit rate, baud rate
1.5 feed of computer networks, Network criteria, advantages of networking
1.6 Network topologies: Mesh, Star, Bus, Tree, Ring and Hybrid topologies - Schematic diagram, working, ad viint‹i disadvantages and applications
1.7 Network Classification:
Based on Transmission Technology
Point to-point, Multipoint, Broadcast
Based on physical size(scale):
PAN, BAN, LAN, MAN, WAN,VPN
based on Architecture: Peer to Peer, client Server, off a esC ent Se er over Peer-to-Peer Model.
This document provides an overview of data communication concepts. It discusses that data communication requires hardware devices and software to exchange data via transmission mediums. There are four key characteristics of effective data communication systems: delivery, accuracy, timeliness, and jitter. Data can be transmitted through various modes including unicasting, multicasting, and broadcasting. Components of data communication systems include messages, senders, receivers, transmission mediums, and protocols. The document also discusses topics such as data transmission methods, network devices like hubs and switches, and challenges in data transmission like attenuation, distortion, and noise.
Error detection and correction, flow and error control and trasmission mediaPANKAJ333
1) Errors can occur during data transmission due to interference that changes signal shapes. There are two types of errors: single-bit errors affecting one bit, and burst errors affecting multiple consecutive bits.
2) Error detection allows a receiver to detect errors without correcting them, using redundancy by adding extra bits. Error correction detects and corrects errors using even more redundancy.
3) Flow control regulates the amount of data sent before waiting for acknowledgment. Error control detects and retransmits damaged frames using automatic repeat request.
4) Transmission media are either guided (wired) using twisted pair, coaxial cable and fiber optics, or unguided (wireless) using radio waves, microwaves and infrared.
This document provides an overview of data communication and transmission fundamentals. It discusses the history of information transmission from early optical systems to modern telecommunication technologies. The basic building blocks of a communication system are described, including the information source, transmitter, channel, receiver and destination. Common network components like clients, servers, and network models are defined. The document also covers data communication circuits, antenna fundamentals, and different network topologies.
Synchronous Optical Networking (SONET) and Synchronous Digital Hierarchy (SDH) are standardized protocols that transfer multiple digital bit streams synchronously over optical fiber using lasers or LEDs. SONET was developed to replace earlier asynchronous systems for transporting large amounts of telephone calls and data traffic over fiber without synchronization problems. SONET defines four layers - path, line, section, and photonic - to move signals across the network. It also defines a hierarchy of electrical signaling levels called STSs and corresponding optical signals called OCs. SONET networks can be configured in point-to-point, multipoint, ring or mesh topologies and provide advantages like reduced complexity, protection, bandwidth efficiency
This document discusses key concepts in communication systems including:
1) The basic elements of a communication system including the information source, transmitter, channel, and receiver.
2) Types of communication including simplex, full duplex, and half duplex as well as analog and digital signals.
3) Modulation and multiplexing which allow signals to be transmitted efficiently over a channel by modifying the signal or combining multiple signals.
This document provides a summary of key concepts in data communication and transmission including:
1) Communication models including simplex, half duplex, and full duplex transmission modes.
2) Analog and digital signals and their characteristics such as periodicity.
3) Concepts such as bandwidth, attenuation, noise, and Shannon's channel capacity formula that influence data transmission rates.
The document discusses key components of communication systems including information sources, transmitters, channels, and receivers. It describes how transmitters prepare and adapt signals for transmission through channels. Modulation techniques are used to shift signal spectra to higher frequencies to adapt signals to channel characteristics and multiplex multiple users. Channels can be guided (wired) or non-guided (wireless) and introduce perturbations. Receivers aim to recover information with high fidelity by filtering unwanted signals. Key parameters for quality include SNR, BER, bandwidth, and transmission power.
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1. Concept and Model of Communications
Concept and Model of Communications
General Communications: face-to-face conversation, write a letter, etc.
Electronic Communications: telephone, wireless phone, TV, radar, etc.
Our Focus Computer Communication
General Communication Model
S(t) T(t) Transmission Tr(t) Sd(t)
Source Transmitter Receiver Destination
System
Microphone Transformer Line/Cable Transformer Speaker
Telephone Encoder Fiber/Air Decoder Earphone
Computer Compress Satellite Uncompress Computer
Scanner Modulator Network Demodulator Printer
Basic Communication Criteria: Performance, Reliability, Security
2. Simplified Communications Model (2)
Source
generates data to be transmitted
Transmitter
converts data into transmittable signals
Transmission System
carries data
Receiver
converts received signal into data
Destination
takes incoming data from the receiver
3. Components of a data communications system
l.Message The message is the information (data) to be communicated.
Popular forms of information include text, numbers, pictures, audio,
and video.
2. Sender The sender is the device that sends the data message.
It can be a computer, workstation, telephone handset, video camera.
3. Receiver The receiver is the device that receives the message.
It can be a computer, workstation, telephone handset, television.
4. Transmission medium The transmission medium is the physical path
by which a message travels from sender to receiver.
Some examples of transmission media include twisted-pair wire,
coaxial cable, fiber-optic cable, and radio waves.
5. Protocol A protocol is a set of rules that govern data communications.
It represents an agreement between the communicating devices.
Without a protocol, two devices may be connected but not
communicating, just as a person speaking French cannot be understood
by a person who speaks only Japanese
4. Transmission Media
Transmission Media
A transmission medium: - a connection between a sender and a receiver
- a signal can pass but with attenuation/distortion
- a special system with a transmission bandwidth
Guided (Wired) Media Unguided (Wireless) Media
(lines) (air, vacuum, water, etc.)
- Twisted pair (0~10MHz) - LF (30~300KHz, Navigation)
- Coaxial cable (100K~500MHz) - MF/HF (300~3000KHz, AM/SW radio)
- Optical fiber (180~370THz) - VHF (30~300MHz, TV & FM radio)
- UHF (0.3~3GHz, TV, mobile phone)
- SHF (3~30GHz, satellite, microwave)
- EHF (30~300GHz, experimental com)
- Infrared (no frequency allocation)
5. What is Data Communications?
Exchange of digital information between two
digital devices is data communication
6. Data Transmission
Data transmission is the transfer of data from
point-to-point often represented as an
electromagnetic signal over a physical point-to-
point or point-to-multipoint communication
channel
A communication channel refers to the
medium used to convey information from a
sender (or transmitter) to a receiver, and it can
use fully or partially the medium.
Examples of channels: copper wires, optical
fibbers or wireless communication channels.
7. Requirements of Data Communications
At least Two Devices ready to communicate
A Transmission Medium
A set of Rules & Procedure for proper
communication (Protocol)
Standard Data Representation
Transmission of bits either Serial or Parallel
8. case of Asynchronous Transmission
Bit synchronisation using Start/stop bits in
In Synchronous Transmission the agreed
pattern of Flag
Signal encoding rules viz. NRZ or RZ
And other higher layer protocol
9. Data Representations
A group of bits are used to represent a
character/number/special symbol/Control
Characters
5-bit code can represent 32 symbols (25=32)
7-bit code can represent 128 symbols (27=128)
8-bit code can represent 256 symbols (28=256)
10. Code Set
A code set is the set of codes representing the
symbols
Very common code sets are :
– ASCII : this is ANSI’s 7-bit American
Standard Code for Information Interchange
ASCII code(7-bit) is often used with an 8th bit
known as parity bit used for detecting errors
during Data Transmission
11. Parity bit is added to the Most Significant bit
(MSB)
– EBCDIC : this is IBM’s 8-bit Extended
Binary Coded Decimal Interchange Code
12. ASCII Code
ASCII is defined in ANSI X3.4
– Corresponding CCITT recommendation is
IA5 (International Alphabet No.5)
– ISO specification is ISO 646
Total 128 codes
– 96 codes are graphic symbols (in row. 2~7 in code
chart).
94 codes are printable
13. And 2 codes viz. SPACE & DEL characters are non printable
– 32 codes control symbols (row. 0 & 1 in code chart)
All are non printable
14.
15.
16. Parallel Transmission and Serial Transmission
Parallel Transmission and Serial Transmission
…011000110111010111…
Segment the 0/1 ?
stream into Sender Receiver
N bits groups
N N N N
… 01…00 01…10 11…10 10…11 …
Parallel Transmission Serial Transmission
0 0 0
1 1 1
1 1 0110001 1
0 Sender 0 0 Receiver
Sender Receiver
0 0 0
0 0 0
1 1 1
P/S converter S/P converter
7 (N) bits are sent together 7 (N) bits are sent one after another
7 (N) lines are needed Only 1 line is needed
17. Parallel Transmission
Parallel transmission allows transfers of multiple data bits at the same
time over separate media
In general, parallel transmission is used with a wired medium that uses
multiple, independent wires
Furthermore, the signals on all wires are synchronized so that a bit
travels across each of the wires at precisely the same time
Engineers use the term parallel to characterize the wiring
17
18. Parallel Transmission
The figure omits two important details:
(1) In addition to the parallel wires that each carry data, a parallel
interface usually contains other wires that allow the sender
and receiver to coordinate
(2) To make installation and troubleshooting easy, the wires for a
parallel transmission system are placed in a single physical
cable
A parallel mode of transmission has two chief advantages:
(1) High speed: it can send N bits at the same time
a parallel interface can operate N times faster than an equivalent serial
interface
(2) Match to underlying hardware: Internally, computer and
communication hardware uses parallel circuitry
a parallel interface matches the internal hardware well
19. Serial Transmission
Serial transmission
sends one bit at a time
It may seem that anyone would choose parallel transmission
for high speeds
However, most communication systems use serial mode
There are two main reasons
(1)serial networks can be extended over long distances at less cost
(2)using only one physical wire means that there is never a timing
problem caused by one wire being slightly longer than another
Sender and receiver must contain a hardware that converts
data from the parallel form used in the device to the serial
form used on the wire
20. Serial Transmission
The hardware needed to convert data between an
internal parallel form and a serial form can be
straightforward or complex
In the simplest case, a single chip that is known as a
Universal Asynchronous Receiver and Transmitter
(UART) performs the conversion
A related chip, Universal Synchronous-Asynchronous
Receiver and Transmitter (USART) handles conversion
for synchronous networks
21. Timing of Serial Transmission
Serial transmission mechanisms can be divided into
three broad categories (depending on how transmissions
are spaced in time):
Asynchronous transmission can occur at any time
with an arbitrary delay between the transmission of two
data items
Synchronous transmission occurs continuously
with no gap between the transmission of two data items
Isochronous transmission occurs at regular intervals
with a fixed gap between the transmission of two data
items
21
22. Asynchronous Transmission
It is asynchronous if the system allows the physical medium to be idle for
an arbitrary time between two transmissions
The asynchronous style of communication is well-suited to applications
that generate data at random
(e.g., a user typing on a keyboard or a user that clicks on a link)
The disadvantage of asynchrony arises from the lack of coordination
between sender and receiver
While the medium is idle, a receiver cannot know how long the medium will
remain idle before more data arrives
Asynchronous technologies usually arrange for a sender to transmit a few
extra bits before each data item
to inform the receiver that a data transfer is starting
extra bits allow the receiver to synchronize with the incoming signal
the extra bits are known as a preamble or start bits
23.
24.
25. Synchronous Transmission
A synchronous mechanism transmits bits of data continually
with no idle time between bits
after transmitting the final bit of one data byte, the sender transmits a bit
of the next data byte
The sender and receiver constantly remain synchronized
which means less synchronization overhead
On a synchronous system
each character is sent without start or stop bits
Synchronous transmission:
A bit stream is segmented into relative large groups/blocks many
characters or bytes
Add control bits at the beginning and end of each block
Frame = H_control_bits + characters (data_bits) + T_control_bits
No gap between two characters in a data block
25
27. Asynchronous Serial Transmission
(RS232 Example)
Because no signal lines are used to convey clock (timing) information, this method
groups data together into a sequence of bits (five to eight), then prefixes them with a
start bit and a stop bit. This is the method most widely used for PC or simple terminal
serial communications.
In asynchronous serial communication, the electrical interface is held in the mark
position between characters. The start of transmission of a character is signaled by a
drop in signal level to the space level. At this point, the receiver starts its clock. After
one bit time (the start bit) come 8 bits of true data followed by one or more stop bits at
the mark level.
The receiver tries to sample the signal in the middle of each bit time. The byte will be
read correctly if the line is still in the intended state when the last stop bit is read.
Thus the transmitter and receiver only have to have approximately the same clock
rate. A little arithmetic will show that for a 10 bit sequence, the last bit will be
interpreted correctly even if the sender and receiver clocks differ by as much as 5%.
It is relatively simple, and therefore inexpensive. However, it has a high overhead,
in that each byte carries at least two extra bits: a 20% loss of line bandwidth.
28. Synchronous Serial Transmission (PS2 Example)
The PS/2 mouse and keyboard implement a bidirectional synchronous serial protocol.
The bus is "idle" when both lines are high (open-collector). This is the only state where
the keyboard/mouse is allowed begin transmitting data. The host has ultimate control
over the bus and may inhibit communication at any time by pulling the Clock line low.
The device (slave) always generates the clock signal. If the host wants to send data, it
must first inhibit communication from the device by pulling Clock low. The host then
pulls Data low and releases Clock. This is the "Request-to-Send" state and signals the
device to start generating clock pulses.
Summary: Bus States
Data = high, Clock = high: Idle state. Data is transmited 1 byte at a time:
Data = high, Clock = low: Communication Inhibited. •1 start bit. This is always 0.
Data = low, Clock = high: Host Request-to-Send
•8 data bits, least significant bit first.
•1 parity bit (odd parity - The number of 1's
in the data bits plus the parity bit always add
up to an odd number. This is used for error
detection.).
•1 stop bit. This is always 1.
•1 acknowledge bit (host-to-device
communication only)
29. Simplex Transmission and Duplex
Simplex Transmission and Duplex
Transmission
Transmission
Direction of data
Simplex Device A Device B
Transmission
One can send and the other can receive
Direction of data at time 1
Half Duplex Device A Device B
Transmission
Direction of data at time 2
Both can send and receive but in different time
Direction of data all the time
Full Duplex Device A Device B
Transmission
Both can send and receive simultaneously
30. Simplex
In simplex mode, the communication is unidirectional.
Only one of the two devices on a link can transmit; the other can only
receive
Keyboards and traditional monitors are examples of simplex devices
key-board can only introduce input; the monitor can only accept output.
The simplex mode can use the entire capacity of the channel to send data
in one direction
31. Half-duplex
In half-duplex mode, each station can both transmit and receive, but
not at the same time.
When one device is sending, the other can only receive, and vice versa
ln a half-duplex transmission, the entire capacity of a channel is taken
over by whichever of the two devices is transmitting at the time.
In half-duplex, the entire capacity of the channel is taken over by the
transmitting (sending).
Walkie-talkies and CB (citizens band) radios are both half-duplex
systems
32. Full-duplex
In full-duplex mode both stations can transmit and receive
simultaneously
In full-duplex mode, signals going in one direction share the capacity of
the link with signals going in the other direction.
This sharing can occur in two ways: either the link must contain two
physically separate transmission paths, one for sending and the other
for receiving; or the capacity of the channel is divided between signals
traveling in both directions.
One common example of full-duplex communication is the telephone
network. When two people are communicating by a telephone line, both
can talk and listen at the same time
33. Communication Standards and Related Organizations
Communication Standards and Related Organizations
Communications need standards for inter-operations of different devices
Standard Organizations:
- ISO (International Standards Organization): ISO number
- ITU (International Telecommunication Union): V.num & X.num
- EIA (Electronic Industries Association): EIA-num
- IEEE (Institute of Electronics Engineers): IEEE.num
- ANSI (American National Standards Institute): ASCII, etc.
- IETF (Internet Society and Internet Engineering Task Force): RFC num
- W3C (World Wide Web Consortium): HTTP, HTML, XML, …
- WAP Forum (Wireless Application Protocol): WAP-num