课程名称︰ 无线行动网路导论 课程性质︰ 选修 课程教师︰ 魏宏宇 开课学院： 电机资讯学院 开课系所︰ 电机系 考试日期（年月日）︰ 2012/5/12 考试时限（分钟）： 150 是否需发放奖励金： 是 （如未明确表示，则不予发放） 试题 : I. Cellular System and Radio Propagation [30%] (a) Why do need paging in cellular network? [6%] (b) Consider the radio propagation models for uplink channel and downlink channel. What might be the differences in TDD system and FDD system in terms of radio propagation characteristics? [6%] (c) If you plan to deploy a cellular system in Taipei City, would you choose GSM 900MHz system or GSM 1800MHz system? Why? [4%] (d) If you plan to deploy a cellular system in Yun-Lin County, would you choose GSM 900MHz system or GSM 1800MHz system? Why? [4%] (e) If you have to use two-ray-ground model for radio propagation modeling, do you think it's a more accurate model for the Taipei City system or Yun-Lin County system? Why? [4%] (f) Briefly explain how FDD/CDMA systems work. If you think it's impossible to implement it, please explain why. [6%] II. Multi-hop Relay Networks [18%] (a) Why is OLSR efficient in terms of routing overhead? Is OLSR more suitable for wireless mesh networks or vehicular ad hoc network? Why? [6%] (b) How do DSR and AODV ensure loop-free routing? Please compare. [6%] (c) Compare the tradeoffs of using expanding ring search in AODV? Is the above answer change for using expanding ring search in DSR. [6%] III. MAC [22%] (a) What is exposed terminal problem? Can IEEE 802.11 resolve it? How? [8%] (b) Explain the basic idea of polling in MAC protocol design. Could we apply polling design for uplink data transmission or downlink transmission or both? Why? [8%] (c) Explain how NAV works in IEEE 802.11. What's the purpose of NAV? [6%] IV. Mobile IP [30%] There are four network domains that support Mobile IP. IP-in-IP tunneling is used for Mobile IP data transmission. NTU network domain uses IP addresses 140.112.x.x. NTUST network domain uses IP addresses 140.118.x.x. NCTU network domain uses IP addresses 140.113.x.x. NTHU network domain uses IP addresses 140.114.x.x. There are one NTU student (John) and one NTUST student (Jane). ● The IP address of HA in NTU is 140.112.19.1. The IP address of FA in NTU is 140.112.19.2. ● The IP address of HA in NTUST is 140.118.118.118. The IP address of FA in NTUST is 140.118.118.123. ● The IP address of HA in NCTU is 140.113.25.19. The IP address of FA in NCTU is 140.113.25.20. ● The IP address of HA in NTHU is 140.114.33.21. The IP address of FA in NTHU is 140.114.33.22. ● NTU student (John) has home address of 140.112.99.10. ● NTUST student (Jane) has home address of 140.118.55.66. (a) NTU student (John) brings his laptop to NTHU and uses the FA. NTUST student brings her smartphone to NCTU and uses the FA. Draw the bi-directional traffic flow between John and Jane. Describe the source/ destination IP addresses in packet headers (both inner and outer header) for every transmission segments. (b) NTU student (John) now returns to NTU. NTUST student (Jane) brings her smartphone to NTHU and obtains an IP address 140.114.14.14 to use. Draw the bi-directional traffic flow between John and Jane. Describe the source /destination IP address in packet headers (both inner and outer header) for every transmission segments. --

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