MIS 2

Low Earth Orbit (LEO)

--Satellites move rapidly relative to point on earth. --Large number needed for global coverage. --Requires only low-power transmitters. --Negligible transmission delay. --LEAST expensive to build and launch. --Shortest orbital life (as low as 5 years).

Medium Earth Orbit (MEO)

--Satellites move relative to point on earth. --Moderate number needed for global coverage. --Requires medium-powered transmitters. --Negligible (very small) transmission delay. --Less expensive to build and launch. --Moderate orbital life (6-12 years).

Types of Orbits

1. Propagation delay 2. Geostationary earth orbit (GEO) 3. Medium earth orbit (MEO) 4. Low earth orbit (LEO)

Pervasive Computing (ubiquitous computing)

A computer environment in which virtually every object has processing power with wireless or wired connections to a global network.

Wireless local area network (WLAN)

A computer network in a limited geographical area that uses wireless transmission for communication.

Personal area network

A computer network used for communication among computer devices close to one person.

Wireless Network Interface card (WNIC)

A device that has a built-in radio an antenna and is essential to enable a computer to have wireless communication capabilities.

Ultra-Wideband (UWB)

A high-bandwidth wireless technology with transmission speeds in excess of 100 Mbps. The high speed makes it good for streaming multimedia for, say, tv or personal computers.

Mobile Computing

A real-time wireless connection between a mobile device and other computing environments, such as the Internet or an intranet.

Short message service (SMS)

A service provided by digital cell phones that can send and receive short text messages (up to 160 characters in length).

Hotspot

A small geographical perimeter within which a wireless access point provides service to a number of users.

Satellite radio (Digital radio)

A wireless system that offers uninterrupted, near CD-quality music that is beamed to your radio from satellites.

Microwave transmission

A wireless system that uses microwaves for high-volume, long-distance, point-to-point communication. **Negative: interference**

Global Positioning System (GPS)

A wireless system that uses satellites to enable users to determine their position anywhere on earth.

Satellite Transmission

A wireless transmission system that uses sttelites for broadcast communications.

Radio

Advantages: a.) High bandwidth b.) Signals pass through walls c.) Inexpensive and easy to install Disadvantages: a.) Creates electrical interference problems b.) Susceptible to snooping unless encrypted.

Infrared

Advantages: a.) Low to medium bandwidth b.) Used only for short distances Disadvantages: a.) Must have unobstructed line of sight

Microwave

Advantages: a.) High bandwidth b.) Relatively inexpensive Disadvantages: a.) Must have unobstructed line of sight b.) Susceptible to environmental interference

Satellite

Advantages: High bandwidth, large coverage area Disadvantages: a.) Expensive b.) Must have unobstructed line of sight c.) Signals experience propagation delay d.) Must use encryption for security.

Wireless Access Point

An antenna connecting a mobile device to a wired local area network.

First Generation (1G)

Cellular used analog signals and had low bandwidth (capacity).

Bluetooth

Chip technology that enables short-range connection (date and voice) between wireless devices.

Wide-Area Wireless Networks

Connects users to the Internet over geographically dispersed territory. Typically operate in a licensed spectrum. They are either "cellular radio" or "broadband."

Internet over Satellite (IoS)

Enables users to access the Internet via GEO satellites from a dish mounted on the side of their homes (often in regions of the world where it's the only option for Internet). Downside: GEO satellite transmissions entail a propagation delay, and they can be disrupted by environmental influences such as thunderstorms.

Protocol

Engagement

Smart phones

In addition to being small enough to easy carry or wear, have sufficient computing power to perform productive tasks, and can communicate wirelessly with the Internet, they often have: --cellular telephony --bluetooth --wi-fi --digital camera --gps --an organizer/scheduler/address book/calculator --access to e-mail and sms messaging --mp3 music player --video player DOWNSIDE: people can use them to copy and pass confidential information.

Micro-browsers

Internet browsers with a small fire size that can work within the low-memory constraints of wireless devices and the low bandwidths of wireless networks.

Wireless Devices

People like them because they can make productive use of formerly wasted, their work places are become more flexible because they can take them with them, and because wireless technology enables us to allocate our working time around personal and professional obligations.

Mobile Commerce (M-Commerce)

Refers to e-commerce (EC) transactions that are conducted in a wireless environment, especially via the Internet.

Short-Range wireless networks

Simplify the task of connecting one device to another, eliminating wires and enabling users to move around while they use the device. Typically connects with range of 100 feet or less.

Fourth Generation (4G)

Still under development and does not fall under one defined technology or standard. "A network that operates on Internet technology, combines this technology with other applications and technologies such as Wi-Fi and WiMax, and operates at speeds ranging from 100 Mbps in cell-phone networks to 1 Gbps in local Wi-Fi networks.

Medium-range wireless networks

The familiar wireless local area networks (WLANs). The most common type is Wireless Fidelity or Wi-Fi.

Propagation Delay

The one-quarter second transmission delay in communication to and from GEO satellites.

Near-Field Communications (NFC)

The smallest of the short-range wireless networks that is designed to be embedded in mobile devices such as cell phones and credit cards.

Wireless Application Protocol (WAP)

The standard that enables wireless devices with tiny display screens, low-bandwidth connections, and minimal memory to access Web-based information and services.

Radio Transmission

Transmission that uses radio-wave frequencies to send data directly between transmitters and receivers. --Travel easily through normal office walls. --Fairly inexpensive and easy to install. --Can transmit data at high speeds

Wireless Mesh Networks

Use multiple Wi-Fi access points to create a wide area network that can be quite large. Ex: spending $ for more wireless access points in streetlights and and power poles in Augusta, Georgia.

Cellular telephones

Use radio waves to provide two-way communication. ****Communicates with radio antennas (towers) placed with adjacent geographic areas called "cells."***

Third Generation (3G)

Uses digital signals and can transmit voice and data up to 384 Kbps when the device is moving at a walking pace, 128 Kbps when moving in a car, and 2 Mbps when the device is in a fixed locations. Supports video, Web browsing, and instant messaging.

Second Generation (2G)

Uses digital signals for voice communication; it provides data communication up to 10 Kbps. 2.5G uses digital signals and provides voice and data communication up to 144 Kbps.

Infrared Transmission

Very fast, large bandwidth; most common for tv/dvd remote controls; not visible to human eyes.

Wireless Fidelity

Wi-Fi A set of standards for wireless local area networks based on IEEE 802.11 standard.

Geostationary Earth Orbit (GEO)

satellites orbit 22,300 miles directly above the equator. These satellites maintain a fixed position above the earth's surface because of their altitude, their orbital period matches the 24-hour period of the earth. For this reason, receivers on the earth do not have to track GEO satellites. GEO satellites are excellent for sending television programs to cable operators and broadcasting directly to homes. --Satellites remain stationary relative to point on earth --Few satellites needed for global coverage. --Transmission delay (approx .25 sec.) --Most expensive to build and launch --Longest orbital life (many years)

Wireless

telecommunications in which electromagnetic waves carry the signal between communicating devices. **makes use of time previously wasted and increases work flexibility**

Wireless transmission media (broadcast media)

transmits signals without wires over the air or in space. Ex: microwave, satellite, radio, and infrared.