Wireless And Mobile Communication Question Paper of 3rd Semester M.Tech(ECE) Download Previous Years Question Paper 3

Roll no.                                                                                                                      Total no. of pages: 02                                                                                                                            Total no. of questions: 08

M.TECH(PE) (Sem.  3^rd)

WIRELESS AND MOBILE COMMUNICATION

Subject code: EC-520

Paper ID: [E0577]

Time: 3 Hrs.                                                                                                 Max Marks:  100

INSTRUCTIONS TO CANDIDATE:

1.     Attempt any five question of eight questions

2.    Each  questions carry TWRNTY marks

Q1.

a)    List the major advantages with the layersd approach to protocols.

b)   What tasks are performed by the transport layer?

c)    With suitable examples explain the difference between connection oriented and connectionless protocols.

Q2.

a)    A CRC is constructed to gnerate a 4-bit FCS for an 11-bit  message. The generator polynomial is X4+X3+1. Drow the shift registercircuit that would perform this task.

b)   Demonstrate that the codes th an 8*8 Walsh matrix are orthogonal to each  other by showing that multiplying any by any other code produces a result of zero.

c)    Why is the primary causeof signal loss in satellite communications>

Q3.

a)    What machanisms would cause breakdown in the reverse link of an IS_95 CDMA systems as the number of  user in sector approaches the theoretical limit?

b)   Explain the difference between open loop and close loop power control.

c)    In a typical mobile IP implementation in a foreign agent, the agent maintains a visitor that contains information about the mobile nodes currently visiting this network. What entries sre essential for  row of the table?

Q4.

a)    What are the key advantages and disadvantages of infrared LANs?

b)   Compare and contrast wired and wireless LANs. What unique concerns must be addressed by the designer of a wireless LAN network?

c)    What characteristics of a wireless LAN present unique securirty  challenges not present in wired LANs.

d)   Briefly define IEEE 802.1 services.

Q5.

a)    In a normal GSM time slot, why would the 26 equalizer training bits  be plecedin the  middle of the frame than at the beinning? What is  the reson for having an 8.25 it gurad period after the data bursts?

b)   Ehat are the incentive for power control in a TDMA network? Name the elements of the GSM system that are involved in the handling  power control.

c)    List and briefly define different perfomance metrics that may e used to make the handoff  decisions.

Q6.

a)    As a mobile unit in communication with a base ststion moves, what factors determine the need for power control and the amount of power  adjustment?

b)   Derive an expression for the number of mobile user in a single cell CDMA system employing a voice activity factor of A and a three sector antenna,. How  dose the capacity change for a multi cell CDMA  system?

c)    Verify that the cell cluster size is N=i2+ij+j2 wherei and j are  integers parameters datermining the co-channel cells.

Q7.

a)    List four significant factors which influence the choice of speech coders in mobile comunication systems. Elabrorate on the tradeoff which are caused by each facror. Rank order the factors basedon your personal view point , and defend your position.

b)   Explain the different types of channels in GSM.

Q8.

a)    What are the principle advantages of  WLL overa wired subscriber loop?

b)   What are the principle advantages of OFDM?

c)    What are the key differences among IEEE 802.16 IEEE 802.16.2, and IEEE 802.16.3?

d)   Briefly explain the bluetooth base band logical channels.