Mobile Communication first unit 2 mark important questions and answers - IT8602 - Hack and Cheat Tools

UNIT I – INTRODUCTION – IT8602

Introduction to Mobile Computing – Applications of Mobile Computing- Generations of
Mobile Communication Technologies-MAC Protocols – SDMA- TDMA- FDMA- CDMA

PART – A

1. Define mobile computing. [May 2019, Nov 2019]
    Mobile Computing is an umbrella term used to describe technologies that enable
   people to access network services anyplace, anytime, and anywhere.
    Mobile computing is defined as the ability to compute remotely while on the move.
    It helps in accessing information from anywhere, anytime and anyplace.
    Mobile computing = Mobile communication + Mobile hardware + Mobile software.
2. List the advantages of mobile computing. [May 2016]
    Location Flexibility.
    Device Portability.
    User Mobility.
    Saves Time.
    Enhanced Productivity.
    Entertainment.
3. What are the limitations of Mobile Computing? [Nov 2016]
    Less range and bandwidth.
    Less secure.
    Less power storage.
    More Interference.
    High risk to health.
4. Differentiate mobile computing and Wireless Networking. [May 2017, Nov 2017,
   May 2018]
5. What are the challenges in mobile communication? [Nov 2018]
    Communication
   o Bandwidth, latency, variability, and reliability of wireless links
   o Channel allocation
    Portability
   o Limitations on physical device characteristics
    Mobility
   o Address migration
   o Location dependency
6. List the applications of Mobile Computing.
    Vehicles
    Emergencies
    Business
    Replacement of wired networks
    Infotainment and more
    Location dependent services
    Follow-on services
    Location aware services
    Privacy
    Information services
    Support services
7. List some Mobile and Wireless devices.
    Sensors
    Embedded controllers
    Pager
    Mobile phones
    Personal Digital Assistant (PDA)
    Pocket computer
    Notebook / laptop
8. List the Wireless LAN technologies.
    IEEE 802.11 b
    IEEE 802.11 a
    IEEE 802.11 g
    IEEE 802.11 n
    Bluetooth
9. State some cellular phone standards.
    Nordic Mobile Telephone (NMT 450, NMT 900)
    Advanced Mobile Phone System (AMPS)
    GSM, GPRS
    CDMA
10. What is the motivation for a specialized MAC? [May 2012]
     It is difficult to implement a collision detection scheme in a wireless environment,
    since collisions are hard to be detected.
     In infrastructure-less networks, the issue of hidden and exposed terminals & near and
    far terminals make a MAC protocol extremely inefficient.
11. State the objectives of MAC protocols. [Nov 2018]
     Use the channel to the maximum.
     Reduce the latency in transmission.
     Join the gap between the frames.
     Delete the frame that contains error.
     Add/remove the MAC address.
12. List the issues in wireless MAC. [May 2018, Nov 2019]
     It is difficult to implement a collision detection scheme in a wireless environment,
    since collisions are hard to be detected.
     In infrastructure-less networks, the issue of hidden and exposed terminals make a
    MAC protocol extremely inefficient.
13. Differentiate hidden and exposed terminal problems in infrastructure-less network.
    [May 2016]
14. “MAC protocol designed for infrastructure based wireless network may not work
    satisfactory in infrastructure-less environment.” – Justify. [Nov 2017]
    Yes, MAC protocol designed for infrastructure based wireless network may not work
    satisfactory in infrastructure-less environment due to collision, hidden and exposed
    terminal problem and also mobility of nodes.
15. Which TDMA scheme is suitable for satellite systems? [May 2014]
     Demand Assigned Multiple Access (DAMA) is also called reservation Aloha, a
    scheme typical for satellite systems.
     DAMA is an explicit reservation scheme. Each transmission slot has to be reserved
    explicitly
     During the reservation period, stations can reserve future slots in the transmission
    period.
     Collisions may occur during the reservation period, the transmission period can then
    be accessed without collision.
16. List some random assignment schemes in MAC. [Nov 2016, May 2017]
     ALOHA
     Slotted ALOHA
     CSMA
     CSMA-CD
     CSMA-CA
17. Give some examples of reservation-based schemes in MAC protocols. [May 2019]
     Demand Assigned Multiple Access (DAMA)
     Packet Reservation Multiple Access (PRMA)
     Reservation TDMA
     Multiple Access Collision Avoidance (MACA)
18. Draw the frequency assignment for radio transmission.[May 2013]
19. Justify that a Barker code has good autocorrelation. [Nov 2012, Nov 2013]
     A code for a certain user should have a good autocorrelation and should be orthogonal
    to other codes.
     The Barker code (+1, –1, +1, +1, –1, +1, +1, +1, –1, –1, –1), for example, has a good
    autocorrelation, (i.e.) the inner product with itself is large, the result is 11.
20. Mention the characteristics of mobile computing.
     Ubiquity: The ability of a user to perform computation from anywhere and anytime.
     Location awareness: Many applications require or value additions by location based
    services.
     Adaptation: Ability to adjust to bandwidth fluctuations without inconveniencing the
    user. Fluctuations can arise due to a number of factors such as handoff, obstacles,
    environmental noise, etc.
     Broadcast: Efficient delivery of data can be made simultaneously to hundreds of
    mobile users.
     Personalization: Services in a mobile environment can be easily personalized
    according to a user’s profile.
21. State the properties of MAC protocol.
     It should implement some rules that help to enforce discipline when multiple nodes
    contend for a shared channel.
     It should help maximize the utilization of the channel.
     Channel allocation needs to be fair. No node should be discriminated against at any
    time and made to wait for an unduly long time for transmission.
     It should be capable of supporting several types of traffic having different maximum
    and average bit rates.
     It should be robust in the face of equipment failures and changing network conditions.
22. What are two different kinds of mobility?
     User Mobility: It refers to a user who has access to the same or similar
    telecommunication services at different places.
     Device Portability: many mechanisms in the network and inside the device have
    to make sure that communication is still possible while the device is moving