CMC important questions - Cellular and Mobile Communications

Question Bank
Unit – I
1.    Describe the principle of operation of cellular mobile system and explain the cellular concept with a neat diagram.
2.    The 2G GSM has 125 channels in the uplink and 125 channels in the down link. Each channel has a bandwidth of 200 kHz. What is the total bandwidth occupied in both uplink and down link?
3.    Why does the mobile phone cell, the basic geographic unit of cellular system, have a hexagonal shape? Explain.
4.    Describe the analog and digital cellular systems and limitations of AMPS standard?
5.    What are the limitations of conventional mobile telephone system and Describe the various generations of wireless mobile systems.
6.    What are the main advantages and disadvantages of various cellular structures?
7.    Compare the basic technological differences between the GSM and CDMA standards.
8.    The GSM utilizes the frequency band 935-960 MHz for forward link and 890-915 MHz for reverse link. Each 25 MHz band is broken into radio channels of 200 kHz. Each radio channel consists of 8 time slots. Find the number of users that can be accommodated in GSM, if
(i) No guard band is assumed.
(ii) A guard band of 100 kHz is provided in the upper and lower end.
Unit -2
1.    Describe the frequency reuse concept in cellular communication system and derive the equation for the frequency reuse ratio.
2.     Why do all cells not have uniform size in a practical cellular network? Explain.
3.    What is the need for frequency reuse? Prove that for a hexagonal geometry, the co-channel reuse ratio is 3, where N= i2ij+ j2 .
4.    Determine the number of cells in clusters for the following values of the shift parameters and in a regular hexagon geometry pattern:
(i) i=2 and j=4
(ii) i=3 and j=3
5.    What is the purpose of cell sectoring? Explain how co-channel interference in a cellular system may be reduced?
  1. Draw the frequency reuse pattern for a cluster size of N=3 and N=7?
  2. What are the various components in a cellular system? Explain briefly?
8.    List the various techniques used to expand the capacity of a cellular system.Explain in detail.
1.    What are the different types of non co-channel interference in a cellular system? Explain.
2.    Explain the effects of antenna design parameters for the interference in a cellular system.
3.    Derive the expression for carrier-to-interference ratio in a cellular system for normal case and worst-case scenario with an omni-directional antenna.?
4.    Determine the minimum cluster size for a cellular system designed with an acceptable value of C/I =18 dB. Assume the path loss exponent as 4 and co-channel interference at the mobile unit from six equidistant cells in the 1st tier.?
  1. How the interference is different from noise in a cellular system? Explain.
6.    What are the different types of interference for a cellular system? Explain in detail.
7.    Explain the co-channel interference reduction factor and derive the general formula for C/I.
  1. What are the various techniques to measure CCI? Explain in detail.
Unit -4
1.    Explain the mobile radio propagation over water and flat open area and write the general expression.?
2.    Describe the effect of antenna height in near and long distance mobile propagation.?
3.    Explain the effects of human made structures for mobile propagation in open area.?
  1. What is mean by foliage? Explain foliage loss.?
  2. Explain in detail about near and long distance mobile propagation.?
6.    Describe the various steps involved in finding antenna height gain in a mobile environment.?
  1. Describe the form of a point-to-point model and explain its types.?
  2. Explain the mobile signal propagation over water and flat area?
Unit -5
1.    What are the different types of antennas used for improving coverage and interference reduction at cell site? Explain them.?
  1. Draw the structure of horn antenna and explain its operation.?
3.    What are the different types of antennas used at cell site? Explain them in detail.?
4.    Define space diversity technique and explain horizontally and vertically oriented space diversity antennas.?
5.    What are the directional antennas? Explain how the directional antennas are useful for reducing the interference.?
6.    How can a high gain broadband umbrella pattern antenna be constructed for cell site? Explain.?
7.    What are the different types of antennas are used as mobile antenna? Draw the structure of patch antenna and explain its operation.?
8.    Explain the concept of diversity antenna spacing in cell site with a simple diagram.?
Unit -6
  1. Describe the grouping of the voice, set-up and paging channels.?
  2. Explain in detail the non-fixed channel assignment.?
3.    Describe the concept of frequency management concern to the numbering the channels and grouping into the subset.?
4.    Explain the channel assignment to the cell sites based on the adjacent channels.?
5.    What are the different types of channel assignment approaches? Explain the channel assignment approach that can be effectively deployed to handle increased traffic situation.?
  1. Explain how paging channels are used for the land originating calls?
7.    What is the importance of frequency management chart? Give the structure of the channels in 800 MHz system with frequency ranges?
  1. Explain the overlaid cells concept in detail?
Unit -7
1.    What are the various handoff strategies based on algorithms of handoff? Explain in detail?
  1. What are the different vehicle locating methods? Explain in detail?
3.    Why do the micro cellular structures have more number of handoffs per second as compared to macro cellular structures? Explain.
4.    What type of handoff is used when a call initiated in one cellular system enters another system before terminating? Explain how it works?
  1. What are the various methods of delaying the handoff? Explain briefly.
6.    What is meant by a dropped call? Explain the factors that influence the dropped call rate.
  1. What is meant by handoff? Describe the classification of handoff processes?
1.    What is meant by handoff initiation? Explain the different methods of handoff initiation with suitable diagrams?
Unit -8
  1. What ate the different types of GSM channels? Explain in detail?
2.    Explain the principle of CDMA with a neat sketch and write its advantages and disadvantages.?
  1. Describe the features and services of GSM?
4.    Explain the principle of TDMA and CDMA techniques with the help of neat diagrams.?

  1. Explain the frame structure of GSM with a neat diagram.
  2. Describe the principle, advantages and disadvantages of CDMA technique.
  3. What are the advantages of digital cellular systems over analog?
  4. Explain a simple GSM network architecture with the help of a neat diagram.
CMC important questions - Cellular and Mobile Communications  CMC important questions - Cellular and Mobile Communications Reviewed by Suresh Bojja on 8/21/2015 11:17:00 AM Rating: 5
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