Network Types and Mobile Devices

Module 1: Communications in a Connected World

Network Types

• The internet has become an indispensable part of daily life
• "Internet" typically refers to a collection of connections
• These connections give people a place to find or share information
• The internet is not owned by any single entity
• It exists as a collection of interconnected networks
• These inter-networks cooperate using common standards to exchange information

Local Networks

• Small home networks link computers to each other and the internet
• Small Office/Home Office (SOHO) networks connect computers in remote offices
• SOHO's can connect to corporate networks
• These networks provide access to centralized and shared resources
• Medium to large networks used by schools and organizations
• Medium to large networks can include many locations with numerous interconnected hosts
• The internet connects hundreds of millions of computers globally

Mobile Devices

• Smartphones integrate functions of telephones, cameras, and GPSs
• Smartphones include those of media players and touch screen computers
• Tablets feature on-screen keyboards
• Tablets allow users to perform many activities previously done on laptops
• Activities include composing emails and browsing online
• Smartwatches link to smartphones, providing alerts, messages, and functions such as heart rate monitoring
• Wearable computers, for example, Google Glass, include screens
• These screens display info in a style similar to a fighter pilot's Head-Up Display(HUD)

Connected Home Devices

• Connected security systems allow remote monitoring and configuration of home features via mobile devices
• Features include climate and lighting
• Household appliances such as refrigerators, ovens, and dishwashers can connect to the internet
• Smart TVs access online content without needing traditional TV service equipment
• Gaming consoles can connect to the internet
• Gaming consoles allow users to download games and play with friends

Other Connected Devices

• Modern Smart Cars access maps, audio, video, etc by connecting to the internet
• Radio frequency identification (RFIDs) tags can be placed on objects
• Radio frequency identification (RFIDs) tags enable tracking or monitoring

Other Connected Devices (Cont.)

• Connected sensors provide data such as temperature, humidity, wind speed, barometric pressure, and soil moisture
• Medical devices like pacemakers, insulin pumps and hospital monitors give alerts related to vital signs

Data Transmission

• Personal data categories are used to classify data types
• Volunteered data is explicitly shared with others, for example, social network profiles
• Volunteered data may include videos, pictures, text, and audio files
• Observed data is captured by recording people's actions, such as location data from cell phones
• Inferred data, such as credit scores, results from the analysis of volunteered/observed data

The Bit

• Computers and networks use binary digits: zeros and ones
• Each bit has a value of 0 or 1
• "Bit" is short for "binary digit"
• A bit is the smallest piece of data
• Humans read words and pictures, while computers interpret patterns of bits
• A byte is a group of eight bits, which represents letters and numbers
• The American Standard Code for Information Interchange (ASCII) represents each character with eight bits

Common Methods of Data Transmission

• Data must be converted into signals
• These converted signals are sent across the network media
• Media refers to the physical medium
• Media examples: copper wire, fiber-optic cable, electromagnetic waves, etc.
• A signal has a particular electrical or optical pattern
• Signals transmit from one connected device to another
• Signal transmission methods: electrical signals using electrical pulses on copper wire
• Signal transmission methods: optical signals converting electrical signals to light pulses
• Signal transmission methods: wireless signals using infrared, microwave, or radio waves

Bandwidth and Throughput

• Bandwidth is the capacity of a medium to carry data
• Digital bandwidth refers to the amount of data flow
• This data flow is measured by the number of bits sent by a medium per second
• bps = Bits per second; the fundamental unit of bandwidth
• kbps = Kilobytes, or thousands, of bits per second; 1 kbps = 1,000 bps = 103 bps
• Mbps = Megabytes, or millions, of bits per second; 1 Mbps = 1,000,000 bps = 106 bps
• Gbps = Gigabytes, or billions, of bits per second; 1 Gbps = 1,000,000,000 bps = 109 bps
• Tbps =Terabytes, or trillions, of bits per second; 1 Tbps = 1,000,000,000,000 bps = 1012 bps
• Throughput measures the transfer of bits across media over a period
• Throughput is impacted by various factors
• Impacting factors: data being sent and received over the connection
• Impacting factors: data types transmitted
• Impacting factors: latency created by number of network devices between source and destination
• Latency is the time it takes data to travel from point to point, including delays

Clients and Servers

• Clients are computer hosts; they use software to request and display information from servers
• Servers are computer hosts; they use installed software to provide information
• The provided information is directed, as needed, to other network hosts
• Email servers operate email server software
• Email client software, like Microsoft Outlook, is used to access email on the server
• Web servers use web server software
• Browser software, such as Windows Internet Explorer, is used to access web pages on the web server
• File servers store central corporate and user files
• Client devices access these files with client software like Windows File Explorer

Peer-to-Peer Networks

• In small businesses or homes, computers often serve as both server and client
• A peer-to-peer (P2P) network links 2 computers via wired or wireless connections
• P2P network advantages include simple setup and low network hardware needs
• P2P networks work best for tasks like file sharing and printer sharing
• P2P Disadvantages include lack of central administration
• Additional P2P disadvantages include lack of security and scalability
• Furthermore, all devices may act as clients and servers, which can slow performance

Peer-to-Peer Applications

• P2P applications enables devices to act as clients and servers
• In P2P, every client is a server and vice versa
• P2P apps require each end device to have a user interface and run a background service
• Both clients can simultaneously send and receive messages

Multiple Roles in the Network

• A single computer can run multiple types of server software
• A computer with server software can provide services to many clients at once
• A PC can function as a file server, a web server, and an email server.

Network Components

• Network infrastructure has 3 hardware types: end devices, intermediate devices, and network media.

End Devices

• The devices people typically interact with are end devices or hosts
• End devices create the interface for users to communicate on the underlying network
• Examples: computers, network printers, security cameras, telephones/teleconferencing equipment
• Examples: mobile devices, smart phones, tablets, PDAs, wireless debit/credit card readers, barcode scanners