Chapter 6

digital signal

A discrete electronic signal that is either high or low. In computer terms, high represents the digital bit 1; low represents the digital bit 0.

router

A hardware device that connects two or more networks in a business setting. At home, a router allows you to connect multiple devices to one high-speed connection.

microwave

A high-frequency radio signal that is sent from one microwave tower to another. Because the signal cannot bend around obstacles, the towers have to be positioned in line of sight of each other.

cellular transmissions

A signal sent using a cell tower.

exabyte

A unit of computer data storage equal to 1 billion gigabytes. According to SearchTarget.com, this amount is roughly equivalent to storing 50,000 years' worth of DVD-quality video.

webmail

A web-based email service, such as Hotmail or Gmail, that can be accessed from any computer connected to the Internet using a web browser.

network operating system (NOS)

Programs that control the flow of data among clients, restrict access to resources, and manage individual user accounts.

firewall

Software and hardware systems that stop those outside a network from sending information into the network or taking information out of it.

satellite communication

Space-based equipment that receives microwave signals from an earth-based station and then broadcasts the signals back to another earth-based station.

Wireless Application Protocol (WAP)

Specifies how mobile devices such as cell phones display online information, such as maps and email.

node

A device connected to a network.

gateway

A device that helps separate, dissimilar networks to communicate with each other.

bridge

A device that helps separate, similar networks to communicate with each other.

network adapter

A device that provides the ability for a computer to connect to a network.

wireless router

A hardware device that allows you to connect multiple networks using wireless communication signals.

wireless access point

A hardware device that contains a high-quality antenna that allows computers and mobile devices to transmit data to each other or to and from a wired network infrastructure.

switch

A hardware device that joins several computers together to coordinate message traffic in one LAN network. Checks the data in a packet it receives and sends the packet to the correct destination using the fastest route.

DSL modem

A piece of hardware that allows you to connect to your existing telephone system, but separates voice from data traffic so you don't lose the use of your telephone while your computer is transmitting or receiving data. DSL stands for digital subscriber line.

cable modem

A piece of hardware that enables you to send and receive digital data using a high-speed cable network based on the cable television infrastructure found in many homes.

wireless modem

A piece of hardware that typically takes the form of a PC card that you slot into a device to provide it with an antenna that can pick up a connection to the Internet.

dial-up modem

A piece of hardware that works with telephone transmissions and changes or manipulates an analog signal so that it can be understood by a computer or fax machine (which only understand digital signals).

intranet

A private network within a company's corporate "walls."

TCP/IP

A protocol that breaks transmissions into small packets of data that are sent on the network. Each packet specifies the order in which the data is to be reassembled. This is the protocol for the Internet.

network protocol

A rule for how data is handled as it travels along a communications channel.

Long Term Evolution (LTE)

A set of 4G wireless standards that involves changes to the wireless infrastructure to increase speed and bandwidth by installing transmitters that operate on different frequency bands to avoid interference.

packet

A small unit of data that is passed along a packet-switched network, such as the Internet.

protocol

A standard that specifies how two devices will communicate by providing rules such as how data should be formatted and coded for transmission. The Internet transmission protocol is indicated in the first part of a website's universal resource locator (URL).

Ethernet

A standard that specifies that there is no central device controlling the timing of data transmission. With this standard, each device tries to send data when it senses that the network is available.

gigabit per second

A transmission at a rate of 1 billion bits per second.

megabit per second

A transmission at a rate of 1 million bits per second.

petabit per second

A transmission at a rate of 1 quadrillion bits per second.

kilobit per second

A transmission at a rate of 1 thousand bits per second.

terabit per second

A transmission at a rate of 1 trillion bits per second.

fiber-optic cable

A transmission medium that uses a protected string of glass that transmits beams of light.

cellular network

A transmission system that sends signals through a cell tower, used to transmit both voice and data in every direction. Each cell tower has its own range, or cell, of coverage.

twisted-pair cable

A type of cable consisting of two independently insulated wires twisted around one another. This type of cable is used to transmit signals over short distances.

topology

How devices in a network are physically arranged and connected to each other.

coaxial cable

The cable used to transmit cable television signals over an insulated wire at a fast speed (millions of bits per second).

network architecture

The design and layout of the communications system; how computers in a network share resources.

5G standards

The fifth generation of wireless telecommunication standards; the stage of broadband mobile communications after 4G.

bandwidth

The number of bits (pieces of data) per second that can be transmitted over a communications medium.

packet switching

The process of breaking data into packets, sending, and then reassembling the original data.

frequency

The speed at which a signal can change from high to low; a signal sent at a faster frequency provides faster transmission.

computer network

Two or more computing devices connected by a communications medium, such as a wireless signal or a cable, that is managed via the operating system to share resources.

hub

Used on older LAN networks to coordinate the message traffic among nodes connected to a network.

WiGig

WiGig is based on the 802.11ad standard and promises speeds of up to 7 Gbps. Operating in the 60 GHz range, it has range limitations.

email server

A computer dedicated to managing the sending, receiving, and storing of email messages.

client

A computer or other device capable of sending data to and receiving data from a server on a network.

802.11 standard

A communications standard used in Wi-Fi networks that tells wireless devices how to connect with each other using a series of access points and radio frequencies to transmit data.

mobile broadband stick

A USB device that acts as a modem to give your computer access to the Internet and that can easily be moved between computers.

wireless LAN (WLAN)

A local area network that uses wireless technology.

hotspot

A location where Wi-Fi access is available.

Internet peer-to-peer (P2P) network

A modification of the peer-to-peer network architecture, used on the Internet to share files.

client/server network

A network architecture in which a computer stores programs and files that any connected device can access.

peer-to-peer (P2P) network

A network architecture in which each computer in the network can act as both server and client.

distributed application architecture

A network architecture that distributes tasks between client computers and server computers.

wireless interface card

A network interface card that uses wireless technology.

Bluetooth

A network protocol that offers short-range connectivity (3 to 300 feet, depending on a device's power class) via radio waves between devices such as cell phones and cars. Bluetooth-enabled devices can communicate directly with each other.

Bluetooth LE (BLE)

A new Bluetooth standard that uses much less power to communicate within the same range as what is now "Classic" Bluetooth. Also called Bluetooth Smart.

metropolitan area network (MAN)

A type of network that connects networks within a city or other populous area to a larger high-speed network; typically made up of several LANs that are managed by a network provider.

wide area network (WAN)

A type of network that serves larger geographic areas.

local area network (LAN)

A type of network where connected devices are located within the same room or building, or in a few nearby buildings.

Radio Frequency Identification (RFID)

A wireless technology primarily used to track and identify items using radio signals.

Wi-Fi

A wireless technology, based on the 802.11 standard in its various versions such as 802.11 a, g, or n, that is used to connect to the Internet via hotspots and radio waves.

standards

Allow different devices to talk to one another. Standards ensure compatibility among devices, specifying how computers access transmission media, the speeds used on networks, the design of networking hardware such as cables, and so on.

WiMAX

Also known as 802.16, this standard uses radio waves to connect with other devices using a WiMAX tower; it is faster and can work over a longer range than Wi-Fi.

ring topology

An arrangement that has computers and other devices connected, one after the other, in a closed loop. Data transmitted on a ring network travels from one computer to the other until it reaches its destination.

bus topology

An arrangement where all the computers and other devices on a network, such as printers, are connected by a single cable.

star topology

An arrangement where all the devices on the network, called nodes, connect to a central device that is a hub or a switch.

repeater

An electronic device that takes a signal and retransmits it at a higher power level to boost the transmission strength. A repeater can also transmit a signal to move past an obstruction, so that the signal can be sent further without degradation.

analog signal

An electronic signal formed by continuous sound waves that fluctuate from high to low.

extranet

An extension of an intranet that allows interaction with those outside the company, such as suppliers and customers.

hybrid cloud

An information technology system in which some computing resources and data are managed internally in conjunction with other computing resources and data that are managed externally by cloud service providers.

server

Any combination of hardware and software that provides a service, such as storing data, to a client, such as your computer.

broadband

Any communications medium that is capable of carrying a large amount of data at a fast speed.

communications system

In the context of a computer network, a system that includes sending and receiving hardware, transmission and relay systems, common sets of standards so all the equipment can "talk" to each other, and communications software.

network interface card (or NIC)

One kind of network adapter card. In most current computers, NICs take the form of a circuit board built into the motherboard of a computer that enables a client computer on a LAN to connect to a network by managing the transmission of data and instructions received from the server.

American National Standards Institute (ANSI)

One of the organizations that establishes network communications standards.

Institute of Electrical and Electronics Engineers (IEEE)

One of the organizations that establishes network communications standards.

tethering

The ability to share the Internet connection of a mobile device with another device via a cable, Bluetooth, or Wi-Fi.

modem

piece of hardware that sends and receives data from a transmission source such as your telephone line or cable television connection. The word modem comes from a combination of the words modulate and demodulate.