internet infrastructure

the internet is a global network connecting millions of computers using a common set of communications protocol called IP (internet protocol)

INTERNET PROTOCOL

it is the imternet standard protocol that provides a common layer over dissimilar naetworks, used to move packets among host computers and through gateways if necessary.

• used to move packets among host computer

• consist of 32 bits

• 4 octets of no. from 0-255

• represented in decimal form instead of binary form

• easy to remember the decimal no. rather than binary form

• consist of two parts ; identify network and identify nodes

• eg : 168.223.210.221

 class A network

• binary address start with 0

• the decimal no can be anywhere from 1 to 126

• the first 8 bits identify the network

• the others bit indicate the host within the network

• exp : 102 . 168 . 212 . 226 ( first 8 bits is 102)

class B network

• binary addresses start with 10

• the decimal no can ne anywhere from 128 to 191

• the no 127 is reversed for loopback and is used for internal testing on the local mechine.

• exp : 168 . 212 . 226 . 204( 168.212 is to identifies the network) 

class C network

• binary addresses start with 110

• the decimal no can be anywhere from 192 to 223

• the first 24 bits identify the network.

• exp : 200 . 168 . 212 . 226 ( 200.168.212 is first 24 bits)

class D network

• binary addresses start with 1110

• decimal no can be anywhere from 224 to 239

• it are used to support multicasting.

class E network

• binary no start with 1111

• decimal no can be anywhere from 240 to 255

• it are used for experimentation

• they neve been documated or utilized in a standard way. 

domain name system, DNS

• is an internet service

• translates domain names like www.hotwired.com into numerical IP addresses like 204.62.131.129.

• it is the naming scheme which consist of a hierarchical sequence of names

internet service provider, ISP

• also called ISPs

• it is a company that provides access to the internet

• equipped with a modem

• ISPs themselves are connected to one another through NETWORK ACCESS POINTS

HTTP

• hyper text transfer protocol

• defines how messages are formatted and transmitted, and what actions web servers and browser should take in response to various command.

unbouded media

• unbouded media is media transport electromagnetic waves without using a physical conductor.
• signals are broadcast through air or water.

They are two type of antenna 

                                                                                                                                

Parabolic dish

it is an antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves. The most common form is shaped like a dish and is popularly called a dish antenna or parabolic dish.

Horn antenna

A horn antenna is used for the transmission and reception of microwave signals. It derives its name from the characteristic flared appearance. The flared portion can be square, rectangular, or conical. The maximum radiation and response corresponds with the axis of the horn. In this respect, the antenna resembles an acoustic horn. It is usually fed with a wave guide.

Satellite microwave

Satellite micro wave transmission is used to transmit signals through out the world. These system use satellites in orbit about 50,000 Km above the earth. Satellite dishes are used to send the signals to the satellite where it is again send back down to the receiver satellite. These transmissions also use directional parabolic antenna’ with in line of side.

In satellite communication micro wave signals at 6 GHz is transmitted from a transmitter on the earth through the satellite position in space. By the time signal reaches the satellites becomes weaker due to 50,000 Km distance. The satellite amplifies week signals and transmits it back to the earth at the frequency less than 6 GHz.

3G

3G system is based on wideband CDMA that operates in 5 MHz of bandwidth and can produce download data rates of typically 384 kb/s under normal conditions and up to 2 Mb/s in some instances. Another 3G standard, cdma2000, was developed by Qualcomm. It uses 1.25 MHz bands to produce data rates to 2 Mb/s. Another version of cdma2000 is an improved IS-95 version. It is a 3GPP2 standard. It can transmit data at a rate to 153 kb/s and up to 2 Mb/s in some cases.

4G

The fourth generation has been defined but we are not in it, yet. Yes, many if not most of the mobile carriers and the various phone and equipment manufacturers actually advertise 4G now. The formal definition of 4G as declared by the 3GPP and the ITU-T is something called Long Term Evolution-Advanced (LTE-A). The standard has not been fully completed but basically it is an improved and enhanced version of LTE that uses wider bandwidth channels and a greater number of MIMO antennas. The theoretical upper data rate is 1 Gb/s. That remains to be seen in practice.

differences between 3G & 4G

1. 3G stands for 3rd generation while 4G stands for 4th generation
2. 3G technologies are in widespread use while 4G compliant technologies are still in the horizon
3. 4G speeds are much faster compared to 3G
4. 3G is a mix of circuit and packet switching network while 4G is only a packet switching network

Cellular phone

is a device that can make and receive telephone calls over a radio link whilst moving around a wide geographic area. It does so by connecting to a cellular network provided by a mobile phone operator, allowing access to the public telephone network. By contrast, a cordless telephone is used only within the short range of a single, private base station.
In addition to telephony, modern mobile phones also support a wide variety of other services such as text messaging, MMS, email, Internet access, short-range wireless communications (infrared, Bluetooth), business applications, gaming and photography. Mobile phones that offer these and more general computing capabilities are referred to as smartphones.

cabling

TWISTED-PAIR CABLE 

Unshielded

• its frequency range is suitable for transmitting both data and voice.
• it consists of two conductor, each with its owwn coloured plastic insulation
• actually, colours are used both to identify the specific conductors in a cable

• two wires are twisted around each other at regular interval, make the cumulative effect of the interference is equal on both wires, resulting the total effect of the noise at the reciever is therefore 0.
• UTP has a lot of advantage like more cheaper, flexible and easy to install
• Electronic Industries Association has developed standards to grade UTP cables by quality, with 1 to 5.

1. fine for voice but inadequate for all but low-speed date communication.
2. suitable for voice and for digital data transmission of up to 4Mbps
3. can be used for data transmission of up to 10Mbs. its standard cable for most telephone systems.
4. can bring the possible transmission rate to 16Mbs
5. used for data transmission up to 100Mbs

Shield

• it has a metal foil or braided-mesh covering that encases each pair of insulated conductors.
• the function of metal casing is prevents the penetration of electromagnetic noise and eleminate crosstalk.
• it also uses the same connectors as UTP.

COAXIAL CABLE

• it carries signals of higer frequency ranges than twisted-pair cable.
• it has central core conductor of solid or standaed wire, encased in an outer conductor of metal foil, braid, or a combination of the two.
• the outer metallic wrapping serves both as a shield against noise and as a second conductor to completes the curcuit.
• the outer also can enclosed in an insulating sheath and the whole cable is protected by a plastic cover

 

 

OPTICAL FIBRE

 

Fiber-optic communication is a method of transmitting information from one place to another by sending pulses of light through an optical fiber. The light forms an electromagnetic carrier wave that is modulated to carry information. First developed in the 1970s, fiber-optic communication systems have revolutionized the telecommunications industry and have played a major role in the advent of the Information Age. Because of its advantages over electrical transmission, optical fibers have largely replaced copper wire communications in core networks in the developed world.
The process of communicating using fiber-optics involves the following basic steps: Creating the optical signal involving the use of a transmitter, relaying the signal along the fiber, ensuring that the signal does not become too distorted or weak, receiving the optical signal, and converting it into an electrical signal.