Evolution of Wireless and Cellular Communications Viva Questions

 Evolution of Wireless and Cellular Communications Viva Questions

Short Viva Question with Answers on Evolution of Wireless and Cellular Communications

Q.1. What are the reasons for developing a cellular mobile telephone system?

Ans. There are so many reasons for developing a cellular mobile telephone system. Few main reasons may be listed as under:

        i.            limitations of conventional mobile telephone systems

      ii.            spectrum efficiency considerations

    iii.            technology, feasibility, and service affordability

Q.2. What are the limitations of conventional mobile telephone systems?

Ans. There are the following three limitations of conventional mobile telephone systems:

(i)                 limited service capability

(ii)               poor service performance

(iii)             inefficient frequency spectrum utilization

Q.3. What are the three major approaches to achieve the ideal mobile telephone system?

Ans. Basically, three major approaches, to achieve the ideal mobile telephone the system, are as under:

(i)                 Single-sideband (SSB), which divides the allocated frequency band into a maximum number of channels.

(ii)               Cellular, which reuses the allocated frequency band in different geographic locations.

(iii)             Spread spectrum or frequency-hopped, which generates many codes over a wide frequency band

Q.4. What are the advantages of broadband cellular service?

Ans.

a)      Convenience

b)      Reduced cost

Q.5. What is the main advantage of digital signaling over analog signaling?

Ans.

1.      Noise interference is less

2.      Cost is less

Q.6. Define analog transmission.

Ans. It refers to the analog signal transmission where content may be analog data or digital data.

Q.7. Define digital transmission.

Ans. It refers to the digital signal transmission where the content has to be digital data combinations of 0's and l's.

Q.8. What is the normal operating range of frequency for cell phones?

Ans. The operating frequency range for cell phones is 825 MHz to 845 MHz (approx).

Q.9. What is the frequency range of microwave transmission?

Ans. The frequency range of microwave transmission is 2GHz to 40 GHz.

Q.10. What is the type of modulation used with AMPS?

Ans. In the AMPS (first telephone system used in the United States) cellular communication was based on a frequency modulation (FM) scheme.

Q.11. What was frequency spectrum allocation in AMPS?

Ans.

·         Mobile transmit spectrum → 824 - 849 MHz

·         Mobile receive spectrum → 869 - 894 MHz

Q.12. How many voice and control channels were possible in mobile transmission under AMPS? Ans.

·         Voice channels → 395

·         Control channels → 21

Q.13. Mention the microwave frequencies.

Ans. The high-frequency radio bands say ultrahigh-frequency (UHF), super high frequency (SHF), and extremely high frequency (EHF) is denoted as microwave frequency range.

Q.14. What are the parameters on which the transmission characteristics depend?

Ans. They depend on the cable parameters like (a) Conductor spacing, (b) Wire diameter, (c) Di-electric constant of the insulator

Q.15. What is the frequency range and application of S, C, and W bands?

Ans.

Band	Frequency range	Applications
S C W	1.5 to 5.2 GHz 3.9 to 6.2 GHz 56 to 100 GHz	Cellular Satellite Future development in cellular applications

 

Q.16. Write a short note on ITU.

Ans. It is International Telecommunication Union and was created in the year 1993. The Future Public Land Mobile Telephone System (FPLMTS) was a worldwide standard. Later it was renamed IMT-2000 in 1995 and it was formulated by ITU. The ITU body headquarters is in Geneva, Switzerland.

Q.17. Mention any two sectors of ITU.

Ans.

(a)    ITU Radio communication sector

(b)   ITU Telecommunication standardization sector.

Q.18. What are the study groups that are organized under ITU-R?

Ans.

(a)    SG-1 spectrum management

(b)   SG-3 radio wave propagation

(c)    SG-4 fixed-satellite service

Q.19. What are the multiple access schemes?

Ans.

(a)    FDMA

(b)   TDMA

(c)    CDMA

Q.20. What is the frequency band used in cellular communication?

Ans. UHF-Ultra high-frequency range (300 to 3000 MHz).

Q.21. Give two applications of the VHF band.

Ans.

(a)    FM broadcast

(b)   Aircraft navigational aids.

 Q.22. List three cellular services.

Ans.

(a)    Cellular telephone service (CTS)

(b)   Personal communication systems (PCS)

(c)    Personal communications satellite systems (PCSS)

Q.23. What are the two main market sectors in wireless environment?

Ans. The two broadly classed wireless market sectors are voice-oriented networks and data-oriented networks.

Q.25. List five wireless local area network standards.

Ans.

1.      IEEE 802.11

2.      IEEE 802.11b

3.      IEEE 802.11a

4.      HIPERLAN-2

5.      HIPERLAN-1

Q.26. What are the different technologies of cellular communication? Give any three examples?

Ans.

(a)    WiFi-e.g.. IEEE 802.11.b standard

(b)   GSM

(c)    CDMA

Q.27. Mention a few popular second generations cellular standards.

Ans.

(a)    Global system mobile (GSM)

(b)   Interim standard-136 (IS-136)

(c)    Pacific digital cellular (PDC)

(d)   Interim standard 95 code division multiple access (IS-95)

Q.28. What is SMS?

Ans. SMS is a short message service and it is one of the popular features of GSM. SMS is a service that allows the subscribers to transmit short and real-time messages to the other subscribers of the same network.

Q.29. Give two examples of 2.5 G and 3 G standards.

Ans.

Examples:

2.5  generation (2.5G) standards HSCSD, GPRS

3rd generation (3G) standards W-CDMA, TD-SCDMA