课程名称︰无线多媒体系统研究 课程性质︰多媒体 课程教师︰吴晓光 开课学院：电资 开课系所︰资工 考试日期（年月日）︰ 2010.5.7 考试时限（分钟）： 180 是否需发放奖励金： 是 （如未明确表示，则不予发放） 试题 : 1. Bluetooth Spread spectrum multiple access use signals wich have a transmission bandwidth that is several orders of magnitude greater than the minimum required RF bandwidth. There are two main types of spread spectrum multiple access techniques: frequency hopping spread spectrum (FH-SS) and direct sequence spread spectrum (DS-SS). (A) Bluetooth adopts FH-SS or DS-SS? (B) Explain how Bluetooth devices avoid collision with other Bluetooth devices(in the same personal area network and in the different personal area network.) (C) Explain how Bluetooth addresses hidden terminal problem? (D) Explain how bluetooth achieves power saving. (E) Within a pico network, does Bluetooth apply CDMA scheme? 2. TCP transmission (A) TCP is a reliable transport protocol tuned to perform well in traditional networks made up of links with low bit-error rates. Explain the following figure. (B) What is the problem for TCP to be carried over wireless environment? (C) Describe the solution of (1) Split Connection Approach. Advantage? Disadvantage? (2) Snoop Protocol (3) Westwood TCP (D) Does SNOOP offer transport layer code running on the base station ? What is the meaning of local retransmission? (E) Can you explain the differences between (i) A new ACK (ii) A spurious ACK (iii) A duplicate ACK for Snoop_ack() scheme? 3. Mobile IP The goal of Mobile IP is to allow a mobile host to send and receive packets addresses with its home address regardless of its current point of attachment to the internet (A) Can you explain what are encapsulation and tunneling for Mobile IP? (B) For security reason, some router will enforce to apple source address filtering . Then what is going to impact mobile IP? (C) Can you have solution for the security limit in (B). (D) Explain what is the disadvantage to adopt enhanced DNS approach to solve the mobility problem? (E) Describe why mobile IP adopts two-tier addressing? (F) Explain what is meaning of f and g function? (G) What is the meaning of triangle routing? How to avoid the triangle routing to optimize the route? (H) Explain how IPv6 avoids triangle routing? 4. Cellular wireless technology Fixed cellular wireless technology provides a means to offer broadband access to multimedia services without requiring extensive copper or fiber subscribe plant.Relatively wide unused spectrum at frequency above 20 GHz has led to the development of fixed broadband wireless access system operating in these bands, such as LMDS (local multipoint distribution system.) (A) Can you explain why LMDS does not turn out to be one of the major broadband solutions as ADSL? (B) Can you explain why the first generation cellular wireless mobile system was once projected by some that cellular industry would only see limited growth? (C) Explain what is software radio and Cognitive Radio. (D) So began Mark Weiser's seminal 1991 paper that described his vision of ubiquitous computing now also called pervaise computing. Can you explain the essence of that vision? Why inplementation attemted by weiser and his colleagues at Xerox PARC fell short? (E) Explain the fourth research trust for pervaise computing: Making uneven conditioning? (F) Can you explain why the growth ofcellular subscribe was moderate before 1980? What are the major boosts for cellular mobile industries after 1980? (G) At the start of 21 century, the wireless mobile markets are witnessing unprecedented growth fueled by an information explosion and a technology resolution. Exaplin (i) the trend in the radio frequency (ii) the trend in the mobile network area. (H) To facilitate the rapid deveploment of 3G wireless mobile standards, two programs were launched to deal with the UMTS (W-CDMA) and cdma 2000 standardization. Both of the system could utilize 5 MHz in each link using frequency-division duplex (FDD). Can you explain why the initial CDMA 2000 system utilizes 1.25 MHz bandwidth in each link? -- 没有不可能的事, 只有不愿做的事 --

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