=========================preview======================
(COMP362)2009_f_midterm_COMP362_552.pdf
Back to COMP362 Login to download
======================================================
HONG KONG UNIVERSITY OF SCIENCE AND TECHNOLOGY

COMP 362: Computer Communication Networks II
MID-TERM EXAMINATION
Fall, 2009

Q1. [10 Points] True or false
Determine whether the following statements are true or false. Circle the answer. Please briefly describe the reasons for your choice.
i. Since both wireless sensor networks and cellular networks use base stations, there is no multihop routing in either type of network.
True False
Solution:
False. Since not all the sensor nodes directly connect to the base station, multihop routing is used in wireless sensor networks. In cellular networks, all nodes directly connect to the base station, so there is no multihop routing between the mobile stations (cell phones) and the base station.
ii. The RTS/CTS handshaking can completely eliminate collisions.
True False
Solution:
False. The RTS/CTS handshaking has an underlying assumption that all hidden nodes are within the transmission range of receivers(e.g. to receive the CTS packet successfully). This assumptions is not 100% true. In addition, RTS packets may still collide. So RTS/CTS cannot avoid collision completely.
iii. If a GPS receiver has line-of-sight connections to 4 GPS satellites, the position of the GPS receiver can be determined.
True False
Solution:
True. 4 Satellites (not on the same plane) uniquely determine a position in a 3-dimensional space, if we know the distances to those satellites
iv. Passive RFID tags require very small batteries.
True False
Solution:
False. Reason: Passive RFID tags have no battery and rely on external energy source to charge its circuitry for computation and wireless transmission.
v. PIM dense mode uses RPF (reverse path forwarding).
True False
Solution:
True. PIM dense mode uses RPF with pruning.

Q2. [16 Points] Multiple choices
Multiple choices. Choose the best answer and write the corresponding letter in the blank space at the beginning of the question.
i. _B__ ___ Which one of the following is the LEAST commonly observed phenomenon or LEAST commonly used technique in wireless communication?
A. Capture effect
B. Collision detection
C. Asymmetric link (e.g., node A can received packets from node B, but node B cannot receive packets from node A)
D. Hidden terminals
ii. A__ Which of the following protocol is likely to be used for communication between a smart phone and a digital camera?
A. Bluetooth B. WiMAX
C. RPF (reverse path forwarding) D. GPRS (GSM 2.5G solution)
E. Geographic forwarding
iii. B_ Which of the following description about LTE (Long Term Evolution) is NOT true?
A. LTE aims at providing broadband data service in cellular systems
B. LTE requires at least a 20MHz continuous frequency band to function correctly.
C. LTE supports mobility
D. LTE can co-exist with 2.5G and 3G GSM systems
iv.
E_ Which of the following are valid approaches for locating (searching) data in a P2P (P