wireless

Nice topic to discuss on, isn't? yeah, i will talk more on this topic of course. ESPECIALLY about wireless in UTM.
WHAT COME INTO UR MIND WHENEVER U HEARD THE WIRELESS TERM?
Yeah, of course we can connect to the internet, without using any wires or cables. Yup, even though ur in a far distance. Wireless communication involves :

• radio frequency
• microwave communication
• infrared (IR) *wow, what do u know..

we can found wireless technology in such devices:

• computers *portable, dekstop,hand-held,pen-based,

* honestly, I really think there are no longer computers without wireless. if there are, do dare tell me.

=P

LAN Cables

There are 4 types of LAN cable:

• UTP - Unshielded Twisted Pair
• STP- Shielded Twisted Pair
• Coaxial Cable
• Fiber Optic Cable

UTP

- it has 4 pairs of wires inside the jacket

- each pair is twisted with a different number of twists per inch to help eliminate interference from adjacent pairs and other electrical devices.

STP

- is type of cable that consist of individual wires wrapped in a foil shielding to help provide a more reliable data communication.

COAXIAL CABLE

- has single copper conductor as its center

- plastic layer provide insulation between the center conductor and a braided metal

- metal helps to block outside interference from fluorescent light, motors and others computers

FIBRE OPTICS

- consists of center glass core surrounded by several layers of protective materials

- it transmit light rather than electronic signal eliminating the problem of electrical interference.

- able to transmit signals over much longer distance than coaxial and twisted pair.

NETWORK HARDWARE

We are going to touch upon on SWITCH & HUB.

SWITCH & HUB

Both devices contain ports to connect the devices together 

via networking cables and to facilitates communication 

between the devices, but they differ in how they transfer 

data.

SWITCH

• Switches control the flow of network traffic based on the address information in each packet. 
• A switch learns which devices are connected to its ports (by monitoring the packets it receives), and then forwards on packets to the appropriate port only. This allows simultaneous communication across the switch, improving bandwidth.
• it helps to reduce the amount of unnecessary traffic that would have occurred if the same information had been sent from every port (as with a hub).

Switches and hubs are often used in the same network; the hubs extend the network by providing more ports, and the switches divide the network into smaller, less congested sections.

HUB

• 'Hub’ is sometimes used to refer to any piece of network equipment that connects PCs together, but it actually refers to a multi-port repeater. This type of device simply passes on (repeats) all the information it receives, so that all devices connected to its ports receive that information.
• Hubs repeat everything they receive and can be used to extend the network. However, this can result in a lot of unnecessary traffic being sent to all devices on the network. 
• Hubs pass on traffic to the network regardless of the intended destination; the PCs to which the packets are sent use the address information in each packet to work out which packets are meant for them. In a small network repeating is not a problem but for a larger, more heavily used network, another piece of networking equipment (such as a switch) may be required to help reduce the amount of unnecessary traffic being generated.

Computer Networking

Lets learn something called COMPUTER NETWORKING.
It is a basic network of two computers connected by a cable  to allow the exchange of data & share resources (photos,files, etc)


Now lets move on several types of network:
LAN =) Local Area Network - usually for small geographical area )ex: home, school, office)
MAN =) Metropolitan Area Network - used in bigger area, consist of multiple LAN. 
WAN =) Wide Area Network- large area too, consists of two or more LAN connected together  using communications of technology internet is the largest WAN
PAN =) Personal Area Network- smaller compared to others  (ex; printer, mobile devices)


WHAT IS ROUTER?
A device that forwards data packets along networks. A router is connected to at least two networks, commonly two LANs or WANs or a LAN network. Routers are located at gateways, the places where two or more networks connect. 

TOPOLOGY

At last, my favourite topic, TOPOLOGY...

here it goes... ehem ehem...

TOPOLOGY IS DIVIDED INTO 2 PART ==> physical topology

                                                                    ==> logical topology

Before we go further, topology is an arrangement or mapping of the element of a network, especially the physical (real) and logical (virtual) interconnections between nodes.

Physical topology :The physical layout of devices on a network or the way that the devices on a network are arranged and how they communicate with each other

 Logical topology :the mapping of the flow of data between the nodes in the network determines the logical topology of the network.

LETS TAKE A LOOK ON MOST COMMON OF PHYSICAL  TOPOLOGY:

LINEAR BUS

• Linear refers to line and linear bus is a network configuration in which each computer is connected to the text in a straight line.  The straight line also known as backbone cable.
• The important characteristic of linear bus is it has a beginning and an end. When it reaches the end, it can bounce back (called as signal bounce) interfering with network communications. Thus, terminators are put at the end of the bus.

RING TOPOLOGY

• In a ring network, every device has exactly two neighbors for communication purposes. All messages travel through a ring in the same direction (either "clockwise" or "counterclockwise"). A failure in any cable or device breaks the loop and can take down the entire network.
• To implement a ring network, one typically uses FDDI, SONET, or TOKEN RING technology. Ring topologies are found in some office buildings or school campuses.

STAR TOPOLOGY

• Alternatively referred to as a star network, a star topology is one of the most common network setups where each of the devices and computers on a network connect to a central HUB. A major disadvantage of this network topology is that if the central hub fails, all computers connected to that hub would be disconnected. Below is a visual example of a simple computer setup on a network using the star topology.

THESE ARE THE 3 MOST COMMON PHYSICAL TOPOLOGY.. à bientôt 

+.+

Chapter 2 *continues....

There are 3 types of transmissions timing :

• Synchronous transmission 
• Asynchronous transmission 
• Isochronous transmission 

Synchronous transmission

Data organised into blocks or groups and transferred at regular specified interval

Asynchronous transmission

the process where transmitted data is encoded with start and stop bits, specifying the beginning and

end of each character.

• Data sent without being synchronized 

Isochronous transmission

data is sent at the same time as other related data to support certain types of real time applications e.g streaming voice, video and music

There are 2 types of direction for data transmission:

• simplex
• duplex 
• half duplex
• full duplex

simplex --> it is one way communications only. Data travels in single direction 

 i.e door bell

• Relatively uncommon in computer

communications

duplex --> half duplex: Data can travel in either direction but only in one direction at a time.

• i.e USB devices 

             --> full duplex: Data can moves in both directions at the same time, such as with a telephones.     Ideal for hardware devices that need to pass large amount of data between each other.

• Many networks and most internet connections are full duplex

Chapter 2

Data Transmission 
How data was transmitted?
It can be transmit by :

– Analog vs digital
– Bandwidth
– Serials Vs Parallel
– Transmission timing
– Transmission directions
– Circuit switched, Packet‐Switched, and Broadcast Connections

Analog transmission uses signals that are exact replicas of a sound wave or image. Signals of varying frequency or amplitude are added to carrier waves with a given frequency of electromagnetic current to produce a continuous electric wave E.g standard phones, fax

machines, and modems.     

Digital transmission the signals are converted into a binary code, which consists of two elements. Digital format is ideal for electronic communication as the string of 1s and 0s can be transmitted by a series of "on/off" signals represented by pulses of electricity or light.

Bandwidth is equal to the amount of data that can be transmitted in a fixed amount of time. Usually, bandwidth is measured in bits per second (bps), Megabits per second (Mbps) and etc. Medium with higher bandwidth can deliver data faster.

Serial vs Parallel Transmission 

Serial Transmission

Serial transmission : data sent one bit at a time, one after another a long a single path

Parallel Transmission 

Parallel Transmission : data is sent at least one byte at a time, each bit in the byte taking separate path

Chapter 1

Procrastination =( 
Of course procrastination never give benefit except troubles. Yup. So, this was what I learnt through my first week in Telecommunication class. Let me briefly describe what was in the introduction of this subject.

What is COMMUNICATION?

the imparting, conveying or exchange of thoughts,

messages, ideas, knowledge or information by

sign and sounds like speech, signals, writing or by behaviour. 

ex:

There are many communication that was found by researchers, but we only learnt one model which is Shannon-Weaver Mathematical Model, 1949.

Below is on of the popular model for communication, by Schramm.

What is TELECOMMUNICATION?
tele= far off
telecommunication means transfer of data from transmitter to receiver across a distance.


 There are 6 elements to make communication occurs: 
1. people: as users
2. procedure :order set of task
3. data/information 
4. hardware : equipment/ device
5. software : program
6. communication/ connectivity  :transmission of data