CS 357 - Computer Networks I

Assignments 1

Due Wednesday May 22, 2002 @ 8:30 a.m.
Due on the CS 357 locker No. 103, MC building, ground floor (beside the elevator)
Do not forget to write CLEARLY your name, your student number, and sign the submission form


  1. Calculate the minimum time required to transmit a bit from location A to location B using a GEO satellite if:
    (a) A and B are very close to each other
    (b) A and B are as far apart as possible to each other, while still being in sight of the same satellite. Note that the earth radius is 6378 Km.

  2. It is desired to send 76800 ASCII characters (ASCII is a 7-bit code) across a RS-232 connection.
    (a) What is the minimum time required to transmit them, if
    1. The line is operated at 9600 baud and set to 7 bits per character
    2. The line is operated at 19200 baud and set to 7 bits per character
    3. The line is operated at 9600 baud and set to 8 bits per character
    4. The line is operated at 19200 baud and set to 8 bits per character
    (b) What is the maximum efficiency (in percentage) in each case?
    Hint: The efficiency means the ratio between the useful part of the signal (data) to the total signal (data + overhead).

  3. Show the waveform diagram to illustrate an asynchronous RS-232 transmission if the data to be sent is ``CS357''. A copy of the ASCII table is included in Appendix 2 of the CS357 textbook.
    Do not forget to include the voltage values in your graph, as well as the start and stop bits.