Internet

The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite (often called TCP/IP, although not all applications use TCP) to serve billions of users worldwide. It is a network of networks that consists of millions of private, public, academic, business, and government networks, of local to global scope, that are linked by a broad array of electronic, wireless and optical networking technologies. The Internet carries an extensive range of information resources and services, such as the inter-linked hypertext documents of the World Wide Web (WWW) and the infrastructure to support email.

Most traditional communications media including telephone, music, film, and television are reshaped or redefined by the Internet, giving birth to new services such as Voice over Internet Protocol (VoIP) and Internet Protocol Television (IPTV). Newspaper, book and other print publishing are adapting to Web site technology, or are reshaped into blogging and web feeds. The Internet has enabled and accelerated new forms of human interactions through instant messaging, Internet forums, and social networking. Online shopping has boomed both for major retail outlets and small artisans and traders. Business-to-business and financial services on the Internet affect supply chains across entire industries.

A Hierarchy of Networks

• From a single computer to LAN 
• From LAN to ISP
• ISP to WWW

internet access Via:

 dial-up,
 landline (over coaxial cable, fiber optic or copper wires),
 T- lines,
 WiFi / WiMAX
 satellite
 GPRS, EDGE. ….
 cell phones
 3G…..

Internet protocol

• Every machine on the Internet has a unique identifying number, called an IP Address.
• The IP stands for Internet Protocol, which is the language that computers use to communicate over the Internet.
• A protocol is the pre-defined way that someone who wants to use a service talks with that service. The "someone" could be a person, but more often it is a computer program like a Web browser., etc.
• An Internet Protocol address (IP address) is a numerical label that is assigned to devices participating in a computer network that uses the Internet Protocol for communication between its nodes
• An IP address serves two principal functions: host or network interface identification and location addressing

Internet protocol

•  A typical IP address looks like this: 216.27.61.137
• To make it easier for us humans to remember, IP addresses are normally expressed in decimal format as a dotted decimal number like the one above.
• But computers communicate in binary form. Look at the same IP address in binary: 11011000.00011011.00111101.10001001

What is the meaning of 161.139.52.254 ?

 

TCP/IP

 TCP/IP (Internet) Applications
 World Wide Web's Hypertext Transfer Protocol (HTTP)
 Simple Mail Transfer Protocol (SMTP)
 File Transfer Protocol (FTP)
 Telnet (Telnet) which lets you logon to remote computers
 Simple Network Management Protocol (SNMP)
 VoIP
 IPTV

Domain Name System (DNS) The Internet naming scheme which consists of a hierarchical sequence of names, from the most specific to the most general (left to right), separated by dots : example ?
 IP (Internet protocol) The Internet standard protocol that provides a common layer over dissimilar networks, used to move packets among host computers and through gateways if necessary.
 IP Address The numeric address of a computer connected to the Internet; also called Internet address.

Wireless Technology

Wireless telecommunications is the transfer of information between two or more points that are not physically connected. Distances can be short, such as a few metres for television remote control, or as far as thousands or even millions of kilometres for deep-space radio communications. It encompasses various types of fixed, mobile, and portable two-way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking. Other examples of wireless technology include GPS units, Garage door openers or garage doors, wireless computer mice, keyboards and Headset (audio), headphones, radio receivers, satellite television, broadcast television and cordless telephones.

Wireless communication involves:

• radio frequency communication
• microwave communication, for example long‐range line of sight via highly directional antennas or short line‐of‐antennas, shortrange communication
• infrared (IR) short‐range communication, for example from remote controls or via IRDA Applications may involve point‐to‐point communication, point‐to‐multipoint communication, broadcasting , cellular networks and other wireless networks.

Devices commonly use wireless networking
technologies:

• portable computers, desktop computers computers, hand‐held computers,
•  personal digital assistants (PDAs), 
• cellular phones, 
• pen‐based computers, 
• pagers, GPS etc

The network is literally classified into four. They are:

1.      PAN (personal area network) – covers the network of personal devices such as printer and mobile devices.

2.      LAN (local area network) – covers relatively small geographical area such as home, school and also office.

3.      WAN (wide area network) – covers large geographical area and consist of two or more LAN connected together using communication technology. Internet is the largest WAN.

4.      MAN (metropolitan area network) – network designed to service the large area such as cities. Consist of multiple LAN and the size is between LAN and WAN.

Type of Wireless Network as stated above:

• Wireless wide area networks (WWANs) 
• Wireless metropolitan area networks (WMANs) 
• Wireless local area networks (WLANs) 
• Wireless personal area networks (WPANs)

Application : Data Networking.

• Infra Red 
• wireless local area networks (WLANs)
• broadband wireless.
• Bluetooth,
• WiMax

- Infrared Data Transmission
• IrDA (Infrared Data Association) is an industry standard for wireless communication with infrared light. (Non RF)
• Many laptops sold today are equipped with an IrDAcompatible transceiver that enables communication with other devices, such as printers, modems, LANs, or other laptops. The transfer speed ranges from 2400 bps to 4Mbps.
• Requires line of sight transmission

- Bluetooth: is an industrial specification for wireless
personal area networks (PANs).

• Designed for very short range 
• <10 m connect and exchange information between devices such as mobile phones, laptops, PCs, printers, digital cameras and video game 
• consoles over a secure,
• globally unlicensed short‐range radio frequency.
• Frequency 2.4 GHz, 
• Data speed up to 3Mbps

- Wi‐Fi the underlying technology of wireless local area
networks (WLAN)

• based on the IEEE 802.11 specifications. 
• used for mobile computing devices, such as laptops, in LANs,increasingly used for more services, including Internet and VoIP phone access, gaming, and basic connectivity of consumer electronics such as televisions and DVD players, or digital cameras 
• Frequency 2.4 GHz
• Range 100‐300 feet(indoor) 300‐900 feet(outdoor

- WiMax :To extend the range of wireless network

• Speed upt to 70Mbps
• Range 30 miles
• Provides access to internet access to fixed location with larger coverage

- Broadband wireless access

• is a technology aimed at providing high‐speed wireless access over a wide area from devices such as personal computers to data networks. According to the 802.16‐2004 standard, broadband means 'having instantaneous bandwidth greater than around 1 MHz and supporting data rates greater than about 1.5 Mbit/s'.

• It is planned to be used in the next few years and is estimated to have a range of 50km (30 miles).

Cellular systems

• 0G
• 1G
• 2G
• 3G
• 4G

1G
1G is short for first‐generation wireless telephone technology. This generation of phones and networks is represented by the brick‐sized analog phones introduced in the 1980’s. Subsequent numbers refer to newer and upcoming technology.






2G
2G phones use digital networks. Going all‐digital allowed for the introduction of digital data services, such as SMS and email. 2G networks and their digital nature also made it more difficult to eavesdrop on mobile phone calls.

3G
3G networks are an in between standard. 3G is seen more as pre4G instead of a standard of its own. The advantage 3G networks have over 2G networks is speed. 3G networks are built to handle the needs of today’s wireless users. This standard of wireless networks increases the speed of internet browsing, picture and video messaging, and handheld GPS use.

4G
4G (AKA Beyond 3G) is like the other generations in that its advantage lies in promised increased speeds in data transmission. There is currently no formal definition for 4G, but there are objectives. One of these objectives is for 4G to become a fully IP‐based system, much like modern computer networks. The supposed speeds for 4G will be between 100 Mbit/s and 1 Gbit/s.