Data Representation and Communication Fundamentals

• Data communication and networking are evolving business and personal interactions.

Introduction

• Immediate and accurate information access is crucial for timely decision-making.
• Businesses rely on computer networks for quick data retrieval
• Understanding network operations, available technologies, and optimal designs are essential.
• Advancements in personal computers and data communication are impacting the way networks work today.
• Technological improvements enable faster and larger signal transmission.
• Evolving services leverage increased capacity, extending telephone services like conference calling and caller ID.
• Data communication research aims to facilitate global data exchange (text, audio, video).
• The aim is to enable fast and accurate information access.
• Chapter topics include data communications, networks, the Internet, protocols, and standards
• An internetwork connects multiple networks together.

Data Communications

• Data communications are the exchange of data between devices using transmission media.
• Effective data communication relies on delivery, accuracy, timeliness, and managing jitter.
• Key components are message, sender, receiver, transmission medium, and protocol.

Telecommunication

• Information sharing can be local/remote - face-to-face or over a distance
• Telecommunication means communication at a distance (tele is Greek for "far").
• Data is the information presented in an agreed-upon form.

Characteristics

• Delivery ensures data reaches the correct destination i.e. the intended device.
• Accuracy guarantees accurate data delivery, unaltered during transmission.
• Timeliness means data delivered promptly, essential for real-time transmission (audio, video).
• Jitter is the variation in packet arrival time, affecting audio/video quality.

Components of a Data Communications System

• Message is the transmitted information in the form of text, audio, or video
• Sender transfers the message via devices like computers, phone, video camera, etc
• Receiver acquires messages through devices like computers, phones, etc.
• Transmission medium is how the message goes from sender to receiver, such as wires or radio waves.
• Protocols are rules governing data transmission, ensuring device compatibility.

Data Representation

• Various forms of data exist like text, numbers, images, audio, and video.

Text

• Text is represented as bit patterns using coding systems like Unicode, which uses 32 bits per character.
• ASCII is a coding system that represents the first 127 Unicode characters, known as Basic Latin.

Numbers

• Numbers are converted directly to binary to simplify calculations, rather than via ASCII

Images

• Images comprise of pixels arranged in a matrix, with pixel size determining resolution.
• Bit patterns create each pixel to represent black-and-white or grayscale tones.
• Color images use RGB (red, green, blue) or YCM (yellow, cyan, magenta) for representation.

Audio

• Audio is continuous, in contrast to text, numbers, and images.

Video

• Video can be continuous (camera) or a series of still images.

Data Flow

• Communication between devices can be simplex, half-duplex, or full-duplex.

Simplex

• Simplex communication allows unidirectional transmission, like keyboards & monitors

Half-Duplex

• In half-duplex mode, devices can transmit or receive, but not simultaneously, like walkie-talkies

Full-Duplex

• Full-duplex (duplex) enables simultaneous transmission and reception, sharing channel capacity, such as telephones.

Networks

• It is a set of devices (nodes) connected for communication.

Distributed Processing

• Networks use distributed processing, where tasks are divided among computers.

Network Criteria

• Performance is measured by transit time, response time, throughput, and delay,.
• Reliability is the measured frequency of failure and the time it takes to recover from this
• Security protects data from unauthorized access, breaches, and data losses.

Type of Connection

• Point-to-point provides a direct link between two devices.
• Multipoint (multidrop) connection shares a link among multiple devices spatially or by time.

Physical Topology Connections

• Physical topology is the network's layout, including mesh, star, bus, and ring structures.

Mesh

• In a mesh topology, each device connects to every other with dedicated links.
• To accommodate a mesh topology, every device on the network must have n - 1 input/output (VO) ports (see Figure 1.5) to be connected to the other n - 1 stations.

Star

• In a star setting, devices connect to a central hub, useful in LANs, although it means less cabling than a mesh network.
• The dependency of the entire topology is a big disadvantage of a star topology

Bus

• A bus utilizes a main cable (backbone) for device connections via drop lines and taps, which is a multipoint topology
• The backbone cable can be laid along the most efficient path, then connected to the nodes by drop lines of various lengths.

Ring

• A ring configuration links devices in a circular fashion, with repeaters.

Hybrid Topology

• Networks can be hybrid, like a star with bus branches.

Network Models

• Standards are needed to ensure different networks can communicate.
• Known standards are the OSI model (seven-layer) and the Internet model (five-layer).

Categories of Networks

• Networks are categorized by size: LAN (local), MAN (metropolitan), and WAN (wide area).

Local Area Network

• LANs are privately owned networks within a limited area like an office.

Wide Area Network

• A WAN provides long-distance data transmission over large areas.
• This type of WAN is often used to provide Internet access.

Metropolitan Area Networks

• MANs cover a town or city, offering high-speed connectivity.

Interconnection of Networks

• Connecting two or more networks creates an internetwork, or internet.

Explore data representation in computing, covering numerical systems, image resolution, and color models like RGB. Understand the fundamental differences between audio, text, and images, and the basics of video creation. Learn about data communication components and transmission mediums.