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CS158a Spring 2007Practice Midterm 1To study for the midterm I would suggest you: (1) Know how to do (by heart) all the practice problems. (2) Go over your notes at least three times. Second and third time try to see how much you can remember from the first time. (3) Go over the homework problems. (4) Try to create your own problems similar to the ones I have given and solve them. (5) Skim the relevant sections from the book. (6) If you want to study in groups, at this point you are ready to quiz each other. The practice midterm is below. Here are some facts about the actual midterm: (a) It is closed book, closed notes. Nothing will be permitted on your desk except your pen (pencil) and test. (b) You should bring photo ID. (c) There will be more than one version of the test. Each version will be of comparable difficulty. (d) One problem (less typos) on the actual test will be from the practice test. [Student Generated Solutions-PDF] 1. Explain the difference between a broadcast link and a point-to-point link. 2. Explain the difference between static and dynamic channel allocation. 3. Draw a diagram of the seven layers of the OSI model and the four layers of the TCP/IP model and show how they correspond. 4. Briefly describe how routing works in ATM. 5. Suppose one has a noiseless channel with a bandwitdth of 5kHz on which signals that use up to 128 discrete levels are sent. What is the maximum data rate of this channel? 6. Explain how an active repeater in a optic fiber network works. 7. Explain the following terms: (a) Frequency division multiplexing, (b) Time Division Multiplexing. (c) Wavelength Division Multiplexing. 8. Suppose two people are both sending data using CDMA. Person A has chip sequence 01010101 and Person B has the chip sequence 11110000. Person A wants to sending a 1, Person B is sending a 0. What will the resulting signal look like. Explain how A's message can be decoded. 9. Suppose we want to encode 1111111 with an 11 bit Hamming code. What would the codeword be? Suppose an error occurred in position 4 when sending this codeword. Explain how it would be corrected. 10. Suppose a 1 bit sliding window protocol is being used. Let SA (resp. SB) denote the event that A (resp. b) sends a packet, let RA (resp. RB) denote the event that A (resp. b) receives a packet. Suppose we have the following sequence of event. SA RB SB RA SB SA RB. Add to these events, consistent sequence and acknowledgement numbers and explain a scenario that could result in these events. |