Chapter 7 Channel organization. Group members Bilal Ahmed Mehmal javed Faisal khan janjua Harris...

23
Chapter 7 Channel organization

description

Bilal Ahmed

Transcript of Chapter 7 Channel organization. Group members Bilal Ahmed Mehmal javed Faisal khan janjua Harris...

Page 1: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Chapter 7Channel organization

Page 2: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Group members

Bilal Ahmed Mehmal javed Faisal khan janjua Harris bashir

Page 3: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Bilal Ahmed

1421-211252

Page 4: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Topics we will cover

Parallel Methods Serial Methods Synchronization Some Advantages Some Disadvantages

Page 5: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Channel Organization

If we want to send data from one point to another point . There are two methods to do it: Parallel method Serial method

Page 6: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Parallel Method

In parallel method all the data will sent at once. If we want to send 8 bit it will use 8 wires to sent data of 8 bit. Each wire carry 1 bit at a time.

00101110

Page 7: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Cont’d

In parallel method, devices will be closer to each other. E.g. Data transmission between computer and printer. In parallel link a separate line is used as a clock signal. Its work is to

inform the user when data is available (DA). Another line may be used by the receiver to inform the sender that

data has been used, and ready for next data (DU). The exchange of signals such as DA (Data Available) and DU (Data

Used) between sender and receiver is called handshake . Rare used because of cost issues but mostly used inside computers.

Page 8: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Harris Bashir

1421-211004

Page 9: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Parallel Method ( Parallel wires)

Page 10: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Advantages and Disadvantages

Advantage: Parallel is faster than serial because more then one bit sent at a time. Parallel transmission is good only for short links and examples are

found in all the computer. Disadvantage: More wires needed. Expensive. not good for long distance.

Page 11: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Serial Method

Each bit is sent over a single wire , one after the other. One bit at a time. So we need one communication channel only . Close or far dose not create problem. Data transfer speed is low as compared to parallel method. Less expensive as compared to parallel because less wire are used.

Page 12: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Mehmal Javed

1421-311079

Page 13: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Serial wire

Page 14: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Cont’d

Data will be sent like this in serial:

In serial method there is no signal line is used to send information about time so in this two methods are use: Asynchronous Synchronous

0 1 1 1 0 0 0 0 0 1

Page 15: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

What is Synchronization

Synchronization is technology that is designed to synchronize a single set of data between two or more devices, automatically copying changes back and forth. Example: Contact list synchronization.Requirements: two or more devices. Local or between network.

Page 16: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Faisal Khan Janjuah

1421-211003

Page 17: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Synchronous

The term synchronous is used to describe a continuous and consistent timed transfer of data blocks.

The synchronous signaling methods use only 1 signal. The receiver uses transitions on that signal to figure out the

transmitter bit rate and timing, and set a local clock to the proper timing.

A pulse from the local clock indicates when another bit is ready.

Page 18: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Cont’dThe timing needed for synchronous connections is obtained from the deviceslocated on the communication link. All devices on the synchronous link must beset to the same clocking.

The following is a list of characteristics specific to synchronous communication: There are no gaps between characters being transmitted. Timing is supplied by modems or other devices at each end of the

connection. Special synchronous characters precede the data being transmitted. The synchronous characters are used between blocks of data for time

session purposes.

Page 19: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Asynchronous

The asynchronous signaling methods use 2 different signals.A pulse on one signal indicates when another bit of information is ready on the other signal.The term asynchronous is used to describe the process where transmitted data is encoded with start and stop bits, specifying the beginning and end of each set (set of data).

Page 20: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Cont’dWhen data is transferred by sender (a binary 0), the receiving system knows that data characters are going to follow. It is for this reason that the start bit, which precedes the data character, is always a space bit (binary 0) and that the stop bit, which signals the end of a character, is always a mark bit (binary 1).

The following is a list of characteristics specific to asynchronous communication: Each character is preceded by a start bit and followed by one or more stop

bits. Gaps or spaces between characters may exist.

Page 21: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Cont’d

Page 22: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

Pros and ConsAdvantages Disadvantages

Asynchronous transmission

Simple, doesn't require synchronization of both communication sides

Cheap, because Asynchronous transmission require less hardware

Set-up is faster than other transmissions, so well suited for applications where messages are generated at irregular intervals, for example data entry from the keyboard and the speed depends on different applications.

A high proportion of the transmitted bits are uniquely for control purposes and thus carry no useful information until all data is transferred.

Synchronous transmission Fast and reliable for data security.

Slightly more complex Hardware is more

expensive

Page 23: Chapter 7 Channel organization. Group members  Bilal Ahmed  Mehmal javed  Faisal khan janjua  Harris bashir.

We welcome sensible questions