NAME:______UNT#:______

CSE 5520

Wireless Networks and Protocols

Fall 2012, Test2

(11/28/2012)

Test2

This is a closed book exam. Read each question carefully. Try to answer each question in the space provided and write clearly and neatly. Show all your work (i.e., formulas, assumptions and math). Make sure to answer to the question and try to give crisp answers (max time: 90 minutes)

______/60

  1. What are the differences between voice and dataservices in a cellular network in terms of the following (7 points)

Voice service / Data service
Bit error rate (tolerance)
Delay tolerance (give in micro/milli/seconds)
Jitter tolerance (give in micro/milli/seconds)
Transmission rates (bits/sec)
Secured transmission (select low/medium
/high/very-high --- select one and discuss why)
  1. What are the functional differences between PCF and PDSN ? What are analogous network elements in a voice-only cellular network (for PCF and PDSN) (2)
  1. Give the bandwidth for a given data connection in the following interfaces. Write down all your assumptions (4points)

Interface / Bandwidth for each connection (bits/sec) (typical)
MS – BSC (data)
BSC-PCF (data)
PCF-PDSN (data)
PDSN--PDSN (data)
  1. Fill in the blanks (2points)

RF frame size for data (bits) ------

Video Packet size (bits) ------

(not data)

  1. List forward control channels and their transmission rates between MS-BS (2 points)
  1. List reverse control channels and their transmission rates between MS-BS (3 points)
  1. What is the impact of increasing the soft-handoff factor in a traditional 2G network and IP-based mesh networked BTS (2 points)
  1. Draw a diagram of a heterogeneous network (with different network elements) that includes PSTN, SS7, Cellular, WiFi, and VoIP (5 points) networks. Clearly specify/discuss the interworking protocols. Discuss two issues for handoff between Cellular—WiFi and Cellular—PSTN (8 points)
  1. What is the impact of increasing the statistical multiplexing factor in a IP-based mesh-based BTS and TDM-based 2G network (2 points)
  1. What are the differences between DCF and PCF in the WiFi MAC protocol? List corresponding applications for DCF and PCF (2 points)
  1. What are the different kinds of timers in the WiFi protocol (2 points) ?
  1. What is the purpose of super frame in the WiFi protocol and how it helps in supporting delay-sensitive applications (2 points) ?
  1. Why do you use exponential back-off algorithm in the WiFi protocol (2 points) ?
  1. How do we fix TCP for tolerating the QoS issues (e.g, loss of packets, and delay) in a cellular network (2 points) ?
  1. List five mobile applications that you plan to use in your project3. (2 points)
  1. Why DVM is used instead of the conventional Java virtual machine (JVM) (2 points)
  1. What is an API level you are using in Android programing (2 points) ?
  1. What is the XML file in Android development that determines which processes will host application components (2 points)

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