Mobile and Satellite Communication (ELEDSE8B) — DU B. Sc. (Hons) Electronics Previous Year Question Papers

Vame of the Paper : Mobile and Satellite Communications Instruction for Candidates (a) What is Spread Spectrum technology? Explain two important features of SS systems. (b) Write any three functional differences between Direct Sequence Spread Spectrum (DSSS) and Frequency Hopping Spread Spectrum (FHSS). (c) Establish three similarity mapping points between OSI reference model and the IEEE 802.11 protocol stack. (d) Briefly comment on Infrared LAN and Spread Spectrum LANs. (e) Why is it necessary to have different uplink and downlink frequencies? Which of two frequencies is higher and why? Q2 (a) Comment on how and why the Spread Spectrum systems qualify for the improved QoS over the conventional FDM and TDM based systems. (b) Differentiate between Narrowband signal fading and Multipath signal fading. (c) Explain TDMA, FDMA and CDMA with the help of proper diagrams. Discuss their role in the Spread Spectrum signal transmission and reception. Q3 (a) What is Pseudo Random Number sequence in CDMA? How is it different from Orthogonal codes? Explain with the help of a suitable example. (b) What is Automatic Repeat Request (ARQ)? Illustrate the working of Go-back-N protocol with the help of a suitable example. (c) Establish a classification of the IEEE 802 standards. Why the IEEE 802.11, 802.15 and 802.16 are considered the benchmark standards? Discuss three major differences between Q4 (a) Discuss the orthogonality of Orthogonal Frequency Division Multiplexing (OFDM) system. Why is it important? How is it used to increase the range and speed of the signal transmission from WLAN to WMAN? (b) List out. and explain five important applications of WiMAX standard (IEEE 802.16). Q5 (a) Explain orbital patterns. What are LEO, MEO and GEO satellite orbits? Briefly explain advantages, disadvantages and applications of placing satellites in these orbits. (b) Explain three basic components of a satellite system - Uplink, Transponder and Downlink. Give their block diagrans. What will happen if any one of these components fail? Q6 (a) An earth station with a transmitter power of 120 Watts, a frequency of 6 GHz and an anterma gain of 42 dB transmits to a satellite repeater. The receiver antenna on the satellite has a gain of 31 dB. If the satellite is in a geosynchronous orbit of 35900 Im above earth, what is the received power in dBm? (b) Discuss the evolution of mobile radio communication systems from early radio systems to mode.in cellular networks. Q7 (a) Discuss three basic components of the GSM architecture. How and why the GPRS is integrated within this framework? (b) Explain with the help of a clear diagram the concepts of cell splitting and cell sectoring? Discuss their comparative advantages to enhance, chapiel` capacity.