Networking and Communication Technologies: LAN, WAN, Wireless, and Cellular Standards

LAN (Local Area Network)

A network covering a small area, such as a room, floor, building, or campus. Memory: LOCAL = little area.

MAN (Metropolitan Area Network)

A network spanning roughly 1-30 miles, about the size of a city. Memory: METRO = city.

WAN (Wide Area Network)

A large network spanning states, countries, or the world. Memory: WIDE = widest area.

PDN (Personal Data Network)

A short-range network connecting a person's devices; Bluetooth is a common example. Memory: PERSONAL devices nearby.

Data Network

A network that carries computer data and voice; it has largely replaced voice-only networks.

Voice Network

A network that transmits telephone signals only.

Network Cloud

A local or remote network containing software, applications, and/or data.

Network Devices

The equipment that connects or uses a network, including workstations, servers, hubs, switches, routers, and telephone switching gear.

Five Layers of TCP/IP

Application, Transport, Network, Network Access (Data Link), and Physical. Memory: All Teachers Need New Phones.

Seven Layers of OSI

Application, Presentation, Session, Transport, Network, Data Link, Physical. Memory: All People Seem To Need Data Processing.

Logical Connection

A connection that exists in software rather than as a direct physical link.

Physical Connection

A connection that exists in hardware, such as cables, connectors, and devices.

Data

Entities that convey meaning, such as music or computer files.

Signal

An electrical or electromagnetic impulse used to encode and transmit data.

Analog

A continuous waveform, such as voice or music.

Digital

A discrete, noncontinuous waveform represented by distinct levels, such as high and low voltage.

Amplitude

The height of a wave above or below a reference point, measured in volts. Memory: amplitude = wave height.

Frequency

The number of complete signal cycles in a period of time. Memory: frequency = how frequently cycles repeat.

Phase

The position of a waveform relative to a moment in time or to time zero.

Attenuation

Loss of signal strength during transmission.

Decibel (dB)

The unit used to measure signal strength gain or loss, including attenuation.

Modulate

To place data onto a carrier signal by varying a property such as amplitude, frequency, or phase.

NRZ-L (Non-Return-to-Zero Level)

Digital encoding in which 1 is sent as zero voltage and 0 as positive voltage; the voltage level represents the bit.

NRZ-I (Non-Return-to-Zero Inverted)

Digital encoding in which a voltage change at the start represents 1 and no change represents 0. Memory: I = invert/change for 1.

ASK (Amplitude Shift Keying)

Digital-to-analog encoding that varies amplitude while frequency and phase remain constant.

FSK (Frequency Shift Keying)

Digital-to-analog encoding that varies frequency while amplitude and phase remain constant.

PSK (Phase Shift Keying)

Digital-to-analog encoding that varies phase while frequency and amplitude remain constant.

PCM (Pulse Code Modulation)

Analog-to-digital conversion that samples an analog waveform at intervals and converts the samples into binary values.

EBCDIC

A character code that assigns binary patterns to textual characters and symbols; associated especially with IBM systems.

ASCII

A character code that represents letters, numbers, symbols, and control characters with binary patterns.

Unicode

A character-encoding standard designed to support characters from many languages; the course example uses 16 bits per character.

Conducted Media

Wired transmission media that guide a signal through a physical path, including twisted pair, coaxial cable, and fiber optics.

Twisted Pair (UTP)

Pairs of copper wires twisted to reduce electromagnetic interference; Categories 5, 6, and 7 are commonly used in LANs.

Coaxial Cable

A central wire surrounded by insulation and a metal shield; it can carry analog signals across many frequencies.

Baseband Coaxial Cable

Thin coaxial cable using digital signaling to carry one data channel; used to interconnect switches.

Broadband Coaxial Cable

Thick coaxial cable using analog signaling to support multiple channels; used for cable television.

Fiber Optics

Thin glass fiber that carries light pulses from a laser or LED; it offers high speed, low noise, and strong security.

Single-Mode Fiber

Thin fiber that uses a laser, supports one light path, and transmits over longer distances.

Multimode Fiber

Thicker fiber that uses an LED, supports multiple light paths, and is suited to shorter distances.

Wireless Media

Transmission media that send signals through the air, including radio, microwave, and infrared waves.

Cell Phones

Mobile wireless devices whose generations progressed from analog service to increasingly fast digital data service.

AMPS (Advanced Mobile Phone Service)

First-generation cellular technology using analog signals and dynamically assigned channels.

D-AMPS (Digital AMPS)

First-generation cellular service in the course materials that adds digital multiplexing techniques to AMPS.

TDMA (Time Division Multiple Access)

Second-generation cellular technology that divides a channel by time and gives each phone a time slice.

CDMA (Code Division Multiple Access)

Second-generation cellular technology that separates phones by assigning each one a unique code.

GSM (Global System for Mobile Communication)

Second-generation digital cellular technology that later developed into GPRS.

GPRS (General Packet Radio Service)

A 2.5-generation packet-data upgrade to GSM, with course-noted rates around 30-40 kbps.

UMTS (Universal Mobile Telephone System)

Third-generation cellular technology also called Wideband CDMA.

LTE (Long-Term Evolution)

Fourth-generation cellular technology with course-noted download rates around 10-15 Mbps.

Broadband / WiMAX

Long-range wireless internet for homes, businesses, and mobile devices using IEEE 802.16; course-noted range is 20-30 miles.

Bluetooth

A short-range wireless standard for point-to-point or point-to-multipoint voice and data transfer among nearby devices.

Terrestrial Microwave

Land-based, line-of-sight transmission using a tightly focused radio beam between ground antennas.

Satellite Microwave

Transmission from an Earth station to a satellite and back to another station, or between satellites.

LEO (Low Earth Orbit)

Satellite orbit roughly 100-1,000 miles above Earth; course examples include wireless email and video conferencing.

MEO (Middle Earth Orbit)

Satellite orbit roughly 1,000-22,300 miles above Earth; GPS is a course example.

GEO (Geosynchronous Earth Orbit)

High orbit used for applications such as weather and television; the course materials list about 22,300 miles.

HEO (Highly Elliptical Orbit)

An elongated satellite orbit used in course examples for government and military observation.

Free Space Optics (FSO)

Short-distance building-to-building transmission using lasers or infrared; fog can interfere with it.

Ultra-Wideband (UWB)

Low-power wireless transmission across a wide range of frequencies at once; it can penetrate walls without line of sight.

Infrared Transmission

Low-power wireless transmission using a focused infrared light beam; examples include remotes and device-to-device transfer.

Zigbee

A low-power, low-data-rate wireless technology for small embedded devices and home or building automation.

Media Selection Criteria

Cost, speed, distance or expandability, environment, and security are the main factors for choosing transmission media.