IT1452-FUNDAMENTALS OF PERVASIVE COMPUTNG Two Marks Questions With Answers 2014

Anna University, Chennai





PERAMBALUR – 621212.



Prepared By : A.Ramachandran / AP


1. What in LAN?

A local area network (LAN) supplies networking capability to a group of computers in close proximity to each other such as in an office building, a school, or a home. A LAN is useful for sharing resources like files, printers, games or other applications. A LAN in turn often connects to other LANs, and to the Internet or other WAN.

2. What is Wireless LAN?

A wireless LAN (or WLAN, for wireless local area network, sometimes referred to as LAWN, for local area wireless network) is one in which a mobile user can connect to a local area network (LAN) through a wireless (radio) connection. The IEEE 802.11 group of standards specify the technologies for wireless LANs. 802.11 standards use the Ethernet protocol and CSMA/CA (carrier sense multiple access with collision avoidance) for path sharing and include an encryption method, the Wired Equivalent Privacy algorithm.

3. What are Advantages of wireless LAN?


Planning, Design, Robustness, Quality Service, Cost,

Proprietary Solution, Restriction,

Safety and Security

4. What is the aim of ubiquitous computing?

Ubiquitous means Present Everywhere. Bringing mobile, wireless and sensor networking technologies together towards a new computing paradigm. Everywhere, anywhere, always on, anytime is the aim.

5. What is Ambient computing?

The concept of ambient intelligence or AmI is a vision where humans are surrounded by computing and networking technology unobtrusively embedded in their surroundings.

6. What is the principle of pervasive computing?

Pervasive computing integrates computation into the environment, rather than having computers which are distinct objects.

7. What is Urban Computing?

Urban computing: the integration of computing, sensing, and actuation technologies into our everyday urban settings and lifestyles. Successful integration r requires taking several facets of the urban environment into account at once.

8. What are the characteristics of pervasive environment?


Prevalence of "Small" Devices

Limited Network Capabilities

High Mobility


Highly Dynamic Environment

9. Define Biometrics.

Biometrics is the science of verifying and establishing the identity of an individual through physiological features or behavioral traits.

10. List down some of the advantages of Biometrics


No need to remember passwords or carry tokens Biometrics cannot be lost, stolen or forgotten More secure than a long password

Solves repudiation problem

Not susceptible to traditional dictionary attacks



1. What are all the characteristics of mobile computing devices?


Data dissemination and Management

Heterogeneity Interoperability Context awareness

2. What is Adaptation?

The vision of mobile computing is to be able to roam seamlessly with your computing devices while continuing to perform computing and communication tasks uninterrupted.

3. What is pull mode?

Pull Mode (on demand): we send an explicit query every time we need particular information. Response will come back.

4. Write the advantages of push mode.

Broad casting frequently requested data items (hot data items) conserves bandwidth.

Highly scalable- same bandwidth is consumed for all the mobile devices. Eliminates Energy consumption – no need of uplink request to data server.

5. Write 5w’s.

Five W's of context can form the core of different context types used by an application

• Who (social context).

• What (functional context).

• Where (location context).

• When (temporal context).

• Why (motivating context).

6. What is a mobile agent?

It is a software program. Moves from machine to machine under its own control. Suspend execution at any point in time, transport itself to a new machine and resume execution. Once created, a mobile agent autonomously decides which locations to visit and what instructions to perform Continuous interaction with the agent’s originating source is not required.

7. What is RPC?

Remote Procedure Calls (RPC). One computer calls procedures on another. Messages are transmitted based on requests and responses. Procedure is “remote” – i.e. it is local to the machine that performs it. Client and Server agree in advance on the protocol for communication.

8. What are the benefits of JAVA?

Platform independent Secure execution Dynamic class loading

Multi-threaded programming

Object serialization

9. Define context awareness.

Context has its origin in the Latin verb contexere, meaning "to weave together."

Two Categories:


Enumeration-based - context is defined in terms of its various categorizations,

Role-based - context is defined in terms of its role in context-aware computing.



1. What are sensor network?

Can be viewed as a Distributed Autonomous System for Information Gathering, Performing data-intensive tasks such as Environment (habitat) monitoring, Seismic monitoring, Terrain Surveillance, etc.

2. What is wireless sensor network?

Wireless Sensor Network (WSN): An autonomous, ad hoc system consisting of a collective of networked sensor nodes designed to intercommunicate via wireless radio.

3. What are the elements of sensor networks?

Sink: sends queries and collects data from

Sensor: monitors phenomenon and reports to

4. What are the networking characteristics?

Sensor Network is an embedded system having the following properties

Self-Configuration: Formation of networks without any human intervention

Self-Healing: Automatic deletion/addition of nodes without resetting the entire network

Dynamic Routing: Adapting Routing schemes on the fly based on the network conditions like Link quality, hop count, gradient, etc.

Multi-Hop Communication: Improving the scalability of the network by sending messages peer-to-peer to a base station

5. Write the classification of Sensor Networks based on their Applications.

Two main classes:

Data gathering sensor networks:

e.g. environment monitoring, temperature monitoring and control. Event detection sensor networks:

e.g. forest fire detection.

6. What is Active RFID?

ACTIVE RFID is powered by batteries allows very low-level signals to be received by the tag. Tag can generate high-level signals back to the reader.

7. Write the advantages of Active RFID.

Read at distances of one hundred feet or more, greatly improving the utility of the device.

It may have other sensors that can use electricity for power.

8. What are all the disadvantages of Passive RFID?

Can be read only at very short distances

It may not be possible to include sensors that can use electricity for power

9. What is RFID Tag Collision?

Tag collision occurs when many tags are present in a small area; but since the read time is very fast, it is easier for vendors to develop systems that ensure that tags respond one at a time.



1. What are all the features of IEEE802.11?

Support of Power Management

Handling Hidden nodes

Ability to operate world wide

2.4 GHz ISM band is used

Data rates- 1 Mbit/s –mandatory , 2 Mbit/s – optional

2. What are Bluetooth?

Standard for wireless communications (WLAN) based on a radio system designed for short-range cheap communications devices suitable to substitute for cables for printers, faxes, joysticks, mice, keyboards, and so on.

3. What is WPAN?

The physical layer (PHY) and medium access control sub layer (MAC) specifications for low rate wireless personal area networks (LR-WPANs), which support simple devices that consume minimal power and typically operate in the Personal Operating Space (POS) of 10 meters or less.

4. What are all the ways of data transfer in WPAN?

Data transfer can happen in three different ways: From a device to a coordinator

From a coordinator to a device or

From one peer to another in a peer-to-peer multi-hop network.

5. What is tunnel?

It is a virtual/transparent pipe between sender (tunnel entry) and receiver (tunnel exit).

6. What is cellular telephony?

Cellular telephony is designed to provide Cellular telephony is designed to provide Communications between two moving units, called mobile stations (MSs), or between one mobile unit and one stationary unit, often called a land unit.

7. Define CDMA?

Code Division Multiple Access systems use codes with certain characteristic to separate different users. To enable access to the shared medium without interference. The users use the same frequency and time to transmit data. The main problem is to find good codes and to separate this signal from noise. The good code can be found by two characteristics 1. Orthogonal 2. Auto correlation.

8. What is polling?

Polling is a centralized scheme with one master and several slave stations. The master can collect the list of stations during the connection phase and can poll these slaves according to many schemes like round robin, random access, reservation schemes etc.

9. Define SAMA.

Spread Aloha Multiple Access is a combination of CDMA and TDMA. The CDMA better suits for connection oriented services only and not for connection less busty data traffic because it requires programming both sender and receiver to access different users with different codes.

10. What is meant by beacon?

A beacon contains a timestamp and other management information used for power management and roaming.

e.g., identification of the base station subsystem (BSS)



1. What is mobile routing?

Even if the location of a terminal is known to the system, it still has to route the traffic through the network to the access point currently responsible for the wireless terminal. Each time a user moves to a new access point, the system must reroute traffic. This is known as mobile routing.

2. What is generic routing encapsulation?

Generic routing encapsulation (GRE) is an encapsulation scheme which supports other network protocols in addition to IP. It allows the encapsulation of packets of one protocol suite into the payload portion of a packet of another protocol suite.

3. What are the requirements for the development of mobile IP standard?

The requirements are: Compatibility Transparency

Scalability and efficiency


4. What is Dynamic source Routing?

Dynamic Source Routing eliminates all periodic routing updates. If a node needs to discover a route, it broadcast a route request with a unique identifier and the destination address as parameters. Any node that receivers a route request gives a list of addresses representing a possible path on its way toward the destination.

5. What is Encapsulation and Decapsulation?

Encapsulation is the mechanism of taking a packet consisting of packet header and data and putting it into the data part of a new packet. The reverse operation, taking a packet out of the data part of another packet, is called decapsulation.

6. What is WAP?

Wireless application protocol (WAP) is a common effort of many companies and organizations to set up a framework for wireless and mobile web access using many different transport systems. Eg. GSM, GPRS, UMTS.

7. Define Flooding and Gossiping.

Flooding - sensor broadcasts packets to all its neighbors till destination reached. Gossiping - sensor sends packets to a randomly selected neighbor.

8. What is WML?

An XML based markup language designed especially for small devices

• Features:

An application can transmit a multiple pages (called cards) simultaneously in a single transmission unit

Concept of events: timer can execute a new page after a certain period of time. Statefull: a variable used in one card can be shared another card.

9. What are IRTS?

IRTS technology we used was developed for application in medical facilities

No interference with laboratory equipment or wireless control or communication systems

Two primary components of the tracking system

The tags and the sensor nodes

The tag is a small, battery operated, mobile, and low power microprocessor about the same size as an adult thumb that is attached to a person’s clothing

Each tag transmits a unique identification (ID) code every four seconds using a blinking infrared (IR) light.

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