Yozshura The protocol optimizer interacts with the existing stack through the tuning layers. The features of wireless LAN are a Power management to save the battery power. List the types of Random Access protocols and Collision Resolution protocols. This union forms a random topology. List the challenges faced by WLAN industry.

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Devasena A. What is meant by path loss? The difference between the effective transmitted power and the received power is called path loss. It represents signal attenuation as a positive quantity measured in db. It may or may not include the effects of antenna gain. What is an ad hoc network? An ad hoc network is a multihop, infrastructure less network which has no centralized server to control the communication between the nodes and resources cannot be reserved beforehand.

It is used in battlefields and military applications. What are the challenging issues in ad hoc network maintenance? What is hidden terminal problem? Hidden terminals are nodes that are hidden or not reachable from the sender of a data transmission session, but are reachable to the receiver of the session.

The hidden terminal can cause collisions at the receiver node. Name some of the outdoor propagation models. Some of the commonly used outdoor propagation models are: i. Longley-Rice model ii. Okumura model Prepared by A. Define — Indoor Propagation Model Indoor propagation model is defined as the model which is used to characterize radio propagation inside the buildings.

The distance covered is much smaller. List out some indoor propagation models. Some indoor propagation models are: i. Long —distance path loss model ii. Ericession multiple break point model iii. Attenuation factor model. Hence the cost staffing, etc. What is free space propagation model? Propagation model which is used to predict received signal strength, when the line-of-sight path is unobstructed between transmitter and receiver is called free space propagation model.

Prepared by A. Why are ad hoc networks needed? The presence of dynamic and adaptive routing protocols enables quick formation of ad hoc networks and is suitable for emergency situations like natural disasters, spontaneous meetings or military conflicts. List the applications of ad hoc networks. Ad hoc networks are widely used in a. Military applications and battlefields b. Collaborative and distributed computing c. Emergency search and rescue operations d. Wireless sensor and mesh networks Distinguish between shadowing and reflection of signal propagation.

Shadowing Reflection When the propagating radio wave hits an Fading caused by the large buildings object which is very large compared to its or other structures, that block the wavelength such as the surface of Earth, or direct transmission path from the tall buildings , the wave gets reflected by transmitter to the receiver is known as that object.

Reflection causes a phase shift of shadowing. What is scattering? When a radio wave impinges on a rough surface, the reflected energy is spread out in all directions.

This is called scattering. It occurs when the wavelength of medium is small when compared to wavelength of travelled wave. Foliage, lamp post, sharp edges. List the transmission impediments of wireless channel. The characteristics of wireless channel are 1. Path loss 2. Fading 3. Interference Prepared by A. Doppler Shift Transmission rate constraints What is fading? List the different types of fading. Fading refers to the fluctuations in signal strength, when received at the receiver.

It occurs due to multipath propagation. The different types of fading are 1. What is meant by small scale fading? Small scale fading is used to describe the rapid fluctuation of the amplitude, phase or multipath delays of a radio signal over a short period of time or travel distance.

What are the factors influencing small scale fading? Factors influencing small scale fading are a Speed of surrounding objects b Multipath propagation c Speed of the mobile d Transmission bandwidth of the signal. MANET is defined as an autonomous system of nodes or Mobile Stations also serving as routers connected by wireless links, the union that forms a communication networks, modeled in the form of an arbitrarily communication graph.

The factors that involves in routing of a MANET are a Modeling of the topology b selection of routers c initiation of a route request Specific underlying characteristics that could serve as heuristics in finding the path efficiently. Unit II 1. List the design goals of a MAC protocol for ad-hoc networks. Design goals of a MAC protocol for ad-hoc networks are a The operation of the protocol should be distributed. List the issues of designing a MAC protocol for ad-hoc networks. The issues of designing a MAC protocol for ad-hoc networks are a Bandwidth efficiency: a.

The ratio of bandwidth used for actual data transmission to the total available bandwidth. MAC protocol should maximize it. MAC protocol should consider the constraint of ad hoc networks for time critical applications c Hidden and exposed terminal problem d Synchronization: a. Nodes are mobile most of the time 3.

What are the two types of protocols used to handle multiple access issues? The two types of protocol that are used to handle multiple access issues are i Contention based protocols ii Conflict free collision free protocols. How contention based protocols are classified? The contention based protocols can be classified into two groups according to the ways collisions are resolved.

They are Prepared by A. List the types of Random Access protocols and Collision Resolution protocols. What are the different types of conflict free protocols? List the features of wireless LAN. The features of wireless LAN are a Power management to save the battery power. Draw the frame format of IEEE The frame format of IEEE What are the classifications of MAC protocol? What are the mechanisms used in the MAC layer?

The mechanisms used in the MAC layer are 1. Contention based protocols 2. Contention based protocols with reservation mechanisms 3. Contention based protocols with scheduling mechanisms 4. Protocols with directional antennas HRMA SRMA A multichannel MAC protocol which is based on half-duplex, very slow TDMA frame based dynamic reservation 1 frequency-hopping spread spectrum MAC protocol FHSS radios Time slot reservation protocol where each Nodes are allocated different time slots so 2 fixed time slot is assigned a frequency that transmissions are collision free channel Uses a reservation and handshake mechanism to enable a pair of Nodes use a collision-avoidance 3 communicating nodes to reserve a handshake mechanism and a soft frequency hop, thereby guaranteeing reservation mechanism collision-free data transmission Developed with the main objective of supporting integrated services of real-time 4 Supports real time transmission and non-real-time application in ad hoc networks Reduced signal interference 2.

Increase in system throughput 3. Improved channel reuse 4. Increase in overall capacity of the channel List the five phases of FPRP. The five phases of FPRP are 1. Reservation request phase 2. Collision report phase 3.

Reservation confirm phase 4. Reservation acknowledge phase 5. List any two needs of real-time MAC protocol.



Devasena A. What is an adhoc network? What is fading? List the different types of fading? Why ad hoc networks are needed?


EC2050 Mobile adhoc networks Apr/may 2017 Reg 2008 question paper download

JoJosar Disadvantages a Updates due to broken links lead to heavy control overhead during mobility. Hence the cost staffing, etc. What ec the two types of protocols used to handle multiple access issues? AMRIS may not exhibit high packet delivery ratio even nites all nodes restrict their mobility to a small region. It occurs due to multipath propagation.

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