[IT802D] Answers to Class Test1 Questions

Following are the correct answers to the questions of the 1st class test. The answers are in blue.

1. Answer the following (5 x 1)
1. What is the frequency band used by a mobile handset? (Depending on the country and the generation of the system, it 900, 12800 or 1900 MHz bands)
2. What is the main difference in the way GSM and CDMA mobile phones communicate? (In GSM several cells are set up and a base station in each cell communicates with the mobile stations. Whereas CDMA does not need that and covers all its users in a region through one access.)
3. What services are provided through GPRS?(Mainly the Internet access)
4. What is the earliest system of mobile communication?(NMT systems in Europe are the oldest, AMPS is the oldest in US)
5. What is the standard for wireless LAN? (The standard governing wireless LAN is the 802.11x family)
2. Answer the following (2 + 3)
1. Describe the advantages of mobile phones over landline phones.( You can communicate even when moving. That is the biggest advantage of the system.Users do not need to be in a fixed location to receive or make calls)
2. What is a cell in cellphone communication, explain with a sketch?(A cell in the cellular system is the area served by one base station. Conceptually they are hezagonal. But, that is only a convenience of representation. With a hexagonal shape you could represent coverage without gaps.)
3. Describe in couple of lines various modulation schemes (max of 5). (5)( Look up the details in the book. Some example schemes could be the Amplitude shift keying, phase shift keying, frequency shift keying, QAM, QPSK etc.)