Communications and Networks
af Chonthicha Chaipanithan
1. Communications
1.1. Computer communications describes a process in which two or more computers or devices transfer data, instructions, and information
2. Uses of Computer Communications
2.1. Users can send and receive wireless messages using wireless messaging services
2.2. Wireless Internet access points allow people to connect wirelessly to the Internet from home, work, school, and in many public locations
2.3. A cybercafé is a coffeehouse, restaurant, or other location that provides personal computers with Internet access to its customers
2.4. A global positioning system (GPS) is a navigation system that consists of one or more earth-based receivers that accept and analyze signals sent by satellites in order to determine the GPS receiver’s geographic location
2.5. GPS receivers
2.6. Collaboration software includes tools that enable users to share documents via online meetings and communicate with other connected users
2.7. Web services enable programmers to create applications that communicate with other remote computers over the Internet or on an internal business network
2.8. A mashup is a Web application that combines services from two or more sources
3. Network Communications Standards
3.1. Ethernet
3.2. Token ring
3.3. TCP/IP
3.4. Wi-Fi
3.5. Bluetooth
3.6. UWB
3.7. IrDA
3.8. RFID
3.9. WAP
4. Communications Over the Telephone Network
4.1. The public switched telephone network (PSTN) is the worldwide telephone system
4.2. ADSL connections transmit data downstream at a much faster rate than upstream
5. Communications Devices
5.1. A communications device is any type of hardware capable of transmitting data, instructions, and information between a sending device and a receiving device
5.2. A dial-up modem converts signals between analog and digital
5.3. A digital modem sends and receives data and information to and from a digital line
5.4. A wireless modem uses the cell phone network to connect to the Internet wirelessly from a notebook computer, a smart phone, or other mobile device
5.5. A network card enables a computer or device to access a network
5.6. Available in a variety of styles
5.7. Wireless network cards often have an antenna
5.8. A wireless access point is a central communications device that allows computers and devices to transfer data wirelessly among themselves or to a wired network
5.9. A router connects multiple computers or other routers together and transmits data to its correct destination on a network
5.10. Many are protected by a hardware firewall
5.11. A hub or switch connects several devices in a network together
6. Wireless Transmission Media
6.1. Cellular radio is a form of broadcast radio that is used widely for mobile communications
6.2. Microwaves are radio waves that provide a highspeed signal transmission
6.3. A communications satellite is a space station that receives microwave signals from an earth-based station, amplifies it, and broadcasts the signal over a wide area
7. Networks
7.1. A network is a collection of computers and devices connected together via communications devices and transmission media
7.2. Advantages of a network include
7.2.1. Facilitating communications
7.2.2. Sharing hardware
7.2.3. Sharing data and information
7.2.4. Sharing software
7.2.5. Transferring funds
7.3. A local area network (LAN) is a network that connects computers and devices in a limited geographical area
7.4. A wireless LAN (WLAN) is a LAN that uses no physical wires
7.5. A metropolitan area network (MAN) connects LANs in a metropolitan area
7.6. A wide area network (WAN) is a network that covers a large geographical area
7.7. The design of computers, devices, and media on a network is sometimes called the network architecture
7.8. P2P describes an Internet network on which users access each other’s hard disks and exchange files directly over the Internet
7.9. A network topology refers to the layout of the computers and devices in a communications network
8. Communications Software
8.1. Communications software consists of programs that
8.1.1. Help users establish a connection to another computer or network
8.1.2. Manage the transmission of data, instructions,and information
8.1.3. Provide an interface for users to communicate with one another
9. Home Networks
9.1. Types of wired home networks
9.1.1. Ethernet
9.1.2. Powerline cable
9.1.3. Phoneline