Question

Q4: Suppose you want to send a 5000 character message, using 7-bit ASCII encoding. How many TOTAL bits would need to be transmitted using an asynchronous connection? How many of those bits are overhead? How many TOTAL bits would need to be transmitted using a synchronous connection? How many of those bits are overhead? For the synchronous connection, each frame can hold 1000 characters, and has a start byte flag, a stop byte flag, a control byte, a 2 byte address field, and a 2 byte checksum. You may show your work for partial credit

Answer 1

Total characters to be transmitted: 5000.

Each character has a 7bit ASCII code. So, that becomes, 5000 x 7 bit= 35,000 bits.

Since it is asynchronous, every character needs a START( 1 bit) and STOP( 1 bit). So 5000 x 2bits = 10,000 bits.

So the total number of bits needed in an synchronous connection is 35,000 + 10,000 = 45,000 bits.

The overhead in asynchronous connection is at least 2 bits for eery character sent( due to START and STOP bits). That makes it, 5000 x 2= 10,000 bits.

For synchronous connection, one frame will look like the following:

For one frame, Start byte(1**) + Control byte (1) + Address byte (2) + Checksum byte (2) +Stop byte (1) + 1000 characters (7 bit each) =7056 bits

For 5 frames*, 7056 x 5=35280 bits

Note * : total characters is 5000. so we need 5 frames.

Note **: 1 byte= 8bits