Viva Questions on Cellular Concept
Viva Questions on Cellular Concept, Cellular Concept Viva Questions, Engineering Viva Questions, Wireless Viva Questions, Cellular Communication Viva Questions
Short Answer Type Questions With Answers
Q.1. Define a cell.
Ans. The smallest geographical area covered by wireless communication is said to be a cell. A base station is located in every cell. The shape of a cell is a hexagon.
Q.2. What are the shapes related to a cell?
Ans. In the early days, three shapes namely (a) Circle, (b) Square, (c) Hexagon
was suggested for a cell. But coverage of signal was very accurate with hexagonal-shaped cells and in a later stage, it was taken as standard.
Q.3. What is an umbrella all pattern?
Ans. In the biggest cellular region say ‘macro cell’, there may be many small cells called microcells and this is known as umbrella cell pattern.
Q.4. What is the use of an umbrella cell?
Ans. In umbrella cell design, signal strength is more and coverage of radio signal is high. Macrocells are used for high-speed traffic and microcells are used for low-speed traffic in the umbrella cellular pattern.
Q.5. What is ACI?
Ans. It is adjacent channel interference and interference takes place due to channels of different frequencies.
Q.6. What are the two types of interferences?
Ans.
- Adjacent channel interference
- Cochannel interference
Q.7. Define Cochannel interference.
Ans. In the cells of different clusters (say N1 and N2) same frequencies are used. The interference due to such kine of cellular frequencies is said to be “Co-channel interference”.
Q.8. Draw a diagram of two clusters from a cellular concept.
Ans.
Q.9. Give one technique to reduce ACI and CCI interferences.
Ans. By carefully allocating channels within a cluster and also between clusters, it is possible to reduce these kinds of interferences.
Q.10. What are the cell shapes possible with a rectangular polygon?
Ans.
- Equilateral triangle
- Square
- Regular hexagon
Q.11. Define cochannel interference.
Ans. In a cellular coverage area when many cells use the same frequency ‘f‘ under the frequency reuse technique, those cells using the same frequency are called as cochannel cells. The interference between the different signals of these cochannel cells is known as cochannel interference.
Q.12. What is the number of cellular channels in a cluster?
Ans. f = GN
Where, f → 4 Number of full-duplex cellular channels
G → Number of channels
N → Number cells in a cluster
Q.13. Draw the hexagonal cellular pattern with two clusters.
Ans.
Fig. 3.18.
Q.14. Write a short note on ‘cluster size’.
Ans. A cluster represents a group of cells in a cellular coverage region. The cluster is denoted as ‘N’ which may be of sizes 4, 7, or 12, etc. The frequency reuse factor is related to cluster size by the equation, frequency reuse factor = 1/N
In a hexagonal shaped cell consideration, the number of cells in one cluster (N), should satisfy the relating, N= i2+ ij+ j2
Where i and j are two non-negative integer values. For example, if i =3 and j = 2 the distance between two cochannel cells within a cluster N (N = 19 here) is shown below. A portion of a cluster of N= 19 is shown here (A of A are cochannel cells)
Q.15. What is the advantage of a hexagon cellular pattern over a circular cellular pattern?
Ans. In hexagon-shaped cells, the radio coverage is highly efficient than circular-shaped cells where the coverage is poor.
Q.16. Define cluster.
Ans. It is a term used for a group of cells, and is denoted generally as ‘N’. If N = 7 then it is termed as seven cell cluster pattern where one cluster consists of seven cells it.
Q.17. What is frequency reuse?
Ans. The same carrier frequencies are reused in cellular communication for effective spectra utilization.