Uttar Pradesh Technical University (UPTU) 2005 B.Tech Electronics and Communications Engineering wireless communication ( ) - Question Paper

B.Tech.
8th Semester Examination,2005-2006
wireless Communications(TEC-031)

Note:Attempt ALL ques..All ques. carry equal marks.

Q.1.Attempt any 4 parts of the following:

(a)If a transmitter produces 50W of power,express transmit power in units of dB and dBm.If

50W is applied to a unity gain antenna with a 900MHz carrier frequency,find the recieved

power in dBm,at a free space distance of 100m from the antenna.What is power received at

10km away assuming unity gain for the receiver antenna?

(b)What are the basic propagation mechanisms used in mobile communication system?

(c)Explain different causes of fading.

(d)Explain Impulse Response Model of a Multipath Channel.

(e)What are various techniques used for small scale multipath measurements?Explain any 1

of them.

(f)What is power delay profile of Multipath Channel?Explain its different important

parameters.

Q.2.Attempt any 4 parts of the following:

(a)If a mobile unit is 10km away from the base station and 15km away from the co-channel

interference.Find the signal to interference ratio at the mobile unit.

(b)Explain the term "Frequency Reuse" in mobile communication.

(c)Discuss about channel assignment stategies.

(d)What are different modulation techniques used for mobile radio?

(e)How much bandwidth is needed for an analog frequency modulated signal that has an audio

bandwidth of 5kHz and a modulation index of 3.How much output SNR improvement would be

found if the modulation index is increased to 5?What is the trade off bandwidth for this

improvement?

(f)What are different accessing techniques used in mobile networks?

Q.3.Attempt any 2 parts of the following:

(a)Give and discuss the examples of Block codes.How are they various than convolution

codes?

(b)Derive the capacity of cellular CDMA.If W=1.25MHz,R=9600bps,and a minimum acceptance

Eb/No.is obtained to be 10dB,determine the maximum number of users that can be supported in a

single cell CDMA system using(1)omnidirectional base station antennas and no voice activity

detection,(2)3sectors at the base station and activity detection with a=3/8.Assume the

system is interference limited.

(c)Discuss about standards of GSM system.

Q.4.Attempt any 2 parts of the following:

(a)What are the IEEE standards provided to wireless LAN?Explain features of the standards.

(b)Describe wireless multimedia.Explain two of its practical applications.

(c)Discuss any 2 of the following:
(1)Paging
(2)Wireless local loop
(3)AMPS


Q.5.Attempt any 2 parts of the following:

(a)Discuss all the parameters relevant to design Land mobile to satellite communication

system.What are advantages and disadvantages of this system?

(b)Discuss the whole structure of 3rd generation cellular system.

(c)What is the concept of universal mobile telecommunication system and how will it be

useful to the society?

Earning:   Approval pending.