CS 313 Networking and Telecommunications Homework 5 (Due via email before 11:00PM, 4/6/2011)

Note:

• Justify your answers and submit your justification along with your answer. You will not get credits by just giving answers.

Total: 20pts

1. (5pts) Suppose that A, C, and D are simultaneously transmitting bits 0, 1, 0, respectively, using a CDMA system with the chip sequences of Fig. 2-28(a) in the textbook. What is the resulting Chip sequence?

2. (12pts) A CDMA receiver gets the following chips: (+1 +1 -1 -1 -3 -3 +1 +1). Assuming the chip sequences defined in Fig. 2.28(a) in the book, which bits did each one send?

3. (3pts) In CSMA/CD, after a collission is detected and the jam signal is sent, each of the senders waits a random amount of time before attempting the transmisson again. Explain the importance of "random amount of time".