Problem Set 1 -- The Physical Layer

Answer each of the questions below. Remember that a correct answer is good, but a convincing answer in which you demonstrate the correctness is better.

This assignment is due 10:00 am, 1 October 2001. Please submit your work at the beginning of class.

1. Describe the fault tolerance (and lack of it) of both the star and ring topologies.
2. Given a connection that has a bandwidth of 400 MHz and a signal to noise ratio of 50 dB, what is the maximum data rate of that line? (Note that the ratio of signal S to noise N is typically expressed in dB, where 10 log₁₀ (S/N) provides the decibel value.)
3. Given an analog signaling scheme that modulates between 2 frequencies, 2 amplitudes, and 4 phases, what is the relationship between the data rate and the baud rate?
4. The IEEE 802.3 (Ethernet) standard dictates that, after the tenth consecutive collision, the range of possible waiting times from which a host randomly makes selection must stop growing. Why is that specification important?
5. Consider n hosts connected to a shared, broadcast medium. If an adaptive tree walk protocol is used for arbitrating this shared medium, what is the maximum number of possible collisions that can occur between successful transmissions?