UNIT I
1.
(a) Describe the model of the mobile transmission medium and fading characteristics and discuss in detail.
(b)Explain coherence bandwidth and delay spread.
2.
(a)Discuss in detail the planning of a cellular system.
(b) Explain about marketing image of hexagonal cells.
3.
(a) Discuss the amplifier noise in cellular frequency band and derive the expression for noise figure.
(b) Explain the operation of a cellular system in detail,
4.
(a) What are the technical difficulties with present wireless communication systems?
(b) What is the significance of propagation, attenuation in mobile radio environment?
5.
(a) Explain the Trunking efficiency?
(b) Distinguish between analog and digital cellular systems.
6.
(a) Draw the block diagram of basic cellular mobile communication systems and explain the function of each block.
(b) What are the spectrum efficiency considerations of an ideal mobile telephone system?
7.
(a) Explain the inefficient spectrum utilization based on the existing mobile systems MTS & IMTS.
(b) Explain the history of 800MHz spectrum allocation to cellular systems.
8.
(a) Explain the direct wave path, line of sight path and obstructive path.
(b)Write in detail about the ignition noise, the 800MHz emission noise and Amplifier noise.
9.
(a) Discuss in detail about mean opinion score of voice quality.
(b)Discuss the evolution and growth of mobile radio communications.
10.
(a) Explain the importance of data links in cellular system.
(b) Discuss analog cellular system(AMPS) in detail?
11.
(a) Discuss the trunking efficiency degradation and compare one carrier/market and other than one carrier per market with necessary graphs.
(b) Discuss the first order & second order statistics of fading.
UNIT II
1.
(a)Give the general formula to find the value of ‘K’ and find out the frequency reuse distance with available ‘K’ value.
(b) What is the concept of frequency reuse and explain how this is useful in increasing the no. of. Channels.
2.
(a) What is a Handoff. Describe Hand off mechanism.
(b) Derive the desired C/I form a Normal case in an omni directional antenna System.
3.
(a) What are the considerations of the components of a cellular system, Explain in detail.
(b) Explain the major elements of cellular mobile radio system.
4.
(a) Explain the frequency reuse schemes.
(b) Explain the maximum number of frequency channels per cell.
5.
(a) How the system capacities are related with the co-channel interference, and derive the expression for signal to interference ratio.
(b) Explain in detail cell splitting concept with neat sketches?
6.
(a) Explain about the co-channel interference reduction factor and derive the general formula for C/I.
(b)If the maximum no of calls per hour Qi in one cell be 5000 and an average calling time T be 1.76 min. The blocking probability is 2%. Find the offered load. If Qi is 30000. Find the offered load compare this with no. of channels by using Erlang B model charts.
7. Discuss:
(a) Maximum no. of calls per hour per cell.
(b) Maximum no. of frequency channels per cell.
(c) Explain about blocking probability of Cellular system.
8.
(a) Mention the two frequency reuse scheme sand explain N-Cell reuse pattern in detail for four & seven cell reuse with illustrative diagrams.
(b)During a busy hour the no. of calls per hour Qi for each 10 cells is 2000, 1500, 3000, 500, 1000, 1200, 1800, 3200, 2600, 800. Assume that 60% of the car phones will be used during this period and that one call is made per car phone. Find the no. of customers in the system.
9.
(a) Draw the general view of telecommunication and explain the function of the each unit?
(b)Distinguish between the permanent splitting and dynamic splitting?
10.
(a) Between the pager , a cellular phone and cordless phone which device will have the longest battery life between charging? Why?
(b).Explain the importance of K=i2+ij+j2.
(c) Present the concept frequency reuse channels and frequency reuse distance?
UNIT III
1.
(a)Distinguish between signal and co-channel interference received by the mobile unit and cell site.
(b)Explain the importance of the antenna height in reduction of co-channel intReference.
2. Explain the following terms used in the cellular system.
(a) Hand off priority
(b) Cross talk
(c) Power control
(d) umbrella pattern.
3.
(a)What is the significance of the sampling delay time t concerned to the real time co channel interference measurement.
(b) Explain the importance of notch in the tilted antenna pattern to reduce the co-channel interference.
4.
(a) Discuss in detail the various techniques to measure co-channel interference, prove That real-time co-channel interference measurement is difficult to achieve in practice.
(b) Explain the causes for near to far end interference.
5.
(a) Mention different systems to reduce the interference.
(b) Explain the effect of antenna pattern on the interference at the base station and mobile unit
6.
(a) Explain the importance of de multiplexer at the receiver to reduce non co-channel interference?
(b)Explain about typical cell site receiver?
7.
(a) What are the different interferences in cellular systems and explain each with diagrams?
(b)Explain how a diversity receiver reduces the interference.
8.
(a) Give the differences between next channel interference and neighboring channel interference.
(b)Explain the occurrence of near-end-far-end interference in one cell and two cell system.
9.
(a) Explain the co-channel interference areas from mobile receivers based on test1.
(b)Explain about the nonlinear amplification in Non co channel interference.
10.
(a) Describe the effect of antenna parameters on cell interferences.
(b)Discuss the diversity schemes for interference reductions at both mobile unit & cell cite.
11.
(a) Prove that for hexagonal geometry the co channel reuse radiois given by Q =3N Where N =i2+ij+j2 .
(b)Describe briefly the importance of noise in the environment at the base station. Explain how location, height and configuration of antennas is selected.
12.
(a) Compare the co channel interference performance of a directional antenna system for K=7 and K = 4?
(b)What is tilting antenna? How can these antenna patterns reduce the co channel interference?
13.
(a)What are the different types of Non-co channel interference? Explain.
(b)Explain the importance of real time co-channel interference?
UNIT IV
1.
(a)IfPr =12W Gt =0 dB Gr =0dB andfc = 900 MHz. Find Pt in watt at a frequency space distance of 1 KM.
(b)Derive the expression for received power in dBW.
2.
(a) Explain the general formula of received power from real model based on shadow case, direct path & over the water condition in detail.
(b) Briefly explain the effect of foliage loss in mobile signal propagation.
3.
(a) Discuss in detail path loss prediction over microcell.
(b)Determine the transfer function of the propagation channel in mobile-to mobile propagation.
4.
(a) Ifh1 =110m use approximate method to find incident angle, elevation angle, ground reflection and reflection point.
(b)What are the different propagation models available for mobile communication, Explain?
5.
(a)What are the factors influencing the fading of the signal and explain different types of Fading.
6. Discuss in detail
(a) The propagation in near distance.
(b) Long distance propagation.
7.
(a) Briefly explain the factors considered for prediction of path loss for a particular mobile radio environment.
(b)Determine maximum & minimum spectral frequency received from a stationary transmitter with a central frequency of 1950 MHz , Assume that the mobile receiver is travelling at speeds of: i) 1KM ii) 5KM iii) 10KM iv) 100KM
8.
(a)Describe all physical circumstances that relate to a stationary transmitter and a moving mobile receiver such that the Doppler shift at the receiver is equal to: i) 0 Hz ii) fd max iii) -fd max iv) fd max/2.
(b)Prove that in two ray ground model =d1-d2= 2hthr/d and state the condition for above expression to present a good approximation.
9.
(a)Consider a transmitter which radiates a sinusoidal carrier frequency of 1850 MHz, For a vehicle moving at 90kmph. Compute the received carrier frequency
if the mobile is moving in a
i. Direction towards the transmitter.
ii. Direction away from the transmitter
iii. Direction, which is perpendicular to the direction of the arrival of the transmitting signal.
(b) Explain the effects of cell site antenna height on cell coverage.
10.
(a)Derive the expression for power received in ground reflected model.
(b) Describe point-to-point prediction model.
11.
(a)Derive the equation for received power between fixed stations.
(b).Explain the mobile propagation obstructive path?
12.
(a) Explain okamura model for predicting path loss in mobile environment.
(b)Explain the effect of propagation of mobile signals over water.
