Deck 8: Understanding Energy Optimization and Latency in Sensor Networks

Question 1

In the S-MAC protocol, ___________is designed to reduce energy consumption during the long idle time when no sensing events happen, by turning off the radio periodically

A)periodic listen only
B)periodic listen and sleep
C)message passing
D)periodic sleep only

Answer 1

periodic listen and sleep

Question 2

__________in S-MAC is similar to the using an RTS/CTS exchange

A)collision avoidance
B)overhearing avoidance
C)both
D)one of above

Answer 2

collision avoidance

Question 3

Following aspects of the energy cost in a sensor network make it challenging to reason about optimizing energy

A)multi-hop communication can be more efficient than direct transmission
B)when a node transmits, all other nodes within range can hear
C)neither a nor b
D)a and b both

Answer 3

a and b both

Question 4

select the correct statement

A)since the nodes operate independently, their clocks may not be synchronized with one another
B)for time synchronization, the wired protocols assume the existence of highly accurate master clocks on some network nodes such as skew clock
C)a and b both
D)neither a nor b

Question 5

select the correct statement

A)since the nodes operate independently, their clocks may not be synchronized with one another
B)for time synchronization, the wired protocols assume the existence of highly accurate master clocks on some network nodes such as atomic clock
C)a and b both
D)neither a nor b

Question 6

The latency in channel can be decomposed into following components

A)send time
B)access time and receive time
C)propagation time
D)alln of above

Question 7

The latency in channel can be decomposed into following components

A)send time and access time
B)receive time and propagation time
C)a and b both
D)neither a nor b

Question 8

The Send time is

A)this is the time taken by the sender to construct the message
B)this is the delay incurred while waiting for access to the transmission channel due to contention, collisions etc
C)this is the time for message to travel across the channel to the destination node
D)this is the time for the network interface on the receiver side to get the message and notify the host of its arrival

Question 9

The Access time is

A)this is the time taken by the sender to construct the message
B)this is the delay incurred while waiting for access to the transmission channel due to contention, collisions etc
C)this is the time for message to travel across the channel to the destination node
D)this is the time for the network interface on the receiver side to get the message and notify the host of its arrival

Question 10

The Propagation time is

A)this is the time taken by the sender to construct the message
B)this is the delay incurred while waiting for access to the transmission channel due to contention, collisions etc
C)this is the time for message to travel across the channel to the destination node
D)this is the time for the network interface on the receiver side to get the message and notify the host of its arrival

Question 11

The Receive time is

A)this is the time taken by the sender to construct the message
B)this is the delay incurred while waiting for access to the transmission channel due to contention, collisions etc
C)this is the time for message to travel across the channel to the destination node
D)this is the time for the network interface on the receiver side to get the message and notify the host of its arrival

Question 12

Receiving power additionally influenced by

A)fading (frequency dependent) & shadowing
B)reflection & refraction depending on the density
C)scattering & diffraction
D)all of above

Question 13

Incorrect statement about Time and frequency multiplexing in combination is

A)better protection against tapping
B)protection against frequency selective interference
C)higher data rates compared to code multiplex
D)no precise coordination required

Question 14

in case of hidden terminal problem

A)two senders are in the communication range of each other
B)two senders are not in the communication range of each other
C)independent of sender range
D)none of the above

Question 15

in case of exposed terminal problem

A)two senders are in the communication range of each other
B)two senders are not in the communication range of each other
C)independent of sender range
D)two receivers are in the communication range of each other

Question 16

Throughput is defined as the number of bits or bytes successfully

A)received per time unit t
B)lost per time unit t
C)transmitted per time unit t
D)retransmitted per time unit t

Question 17

Design Criteria for Medium Access Protocols

A)maximize the throughput by minimizing the delay and energy spent.
B)maximize the throughput by maximize the delay and minimizing energy spent.
C)minimize the throughput by minimizing the delay and energy spent.
D)maximize the throughput by maximize the delay and energy spent.

Question 18

Design Criteria for Medium Access Protocols

A)maximize the throughput by maximize the delay and energy spent.
B)to minimize the time in listening mode as much as possible.
C)to maximize the time in listening mode as much as possible.
D)avoid the switched off devices handling

Question 19

Microcontroller has current drawn typically of 1.8 mA and 5.1 µA respectively in

A)active mode and sleep mode
B)sleep mode and active mode
C)ideal mode and active mode
D)sleep mode and ideal mode

Question 20

RF Transceiver draws more current in

A)sleep mode
B)receive mode
C)transmit mode
D)search mode

Question 21

In centralized TDMA,

A)the schedule is calculated online and provided when required
B)the schedule is calculated offline and provided to the sensor nodes at startup.
C)the schedule is calculated offline and provided when required
D)the schedule is calculated online and provided when after regular interval of time

Question 22

When a node has a packet to send, it listens for traffic on the channel.

A)if the channel is free, it initially sends message, cts.
B)if the channel is free, it initially waits for message, cts.
C)if the channel is free, it initially sends message, rts.
D)if the channel is free, it initially waits for message, rts.

Question 23

If the channel is busy, continues sensing the channel until it becomes idle again.

A)1-persistent csma
B)non-persistent csma
C)p-persistent csma
D)o-persistent csma

Question 24

If the channel is busy, it back-offs for a random amount of time and then retries.

A)1-persistent csma
B)non-persistent csma
C)p-persistent csma
D)o-persistent csma

Question 25

This version is time scheduled. A central controller in the network assigns a fixed transmission order

A)1-persistent csma
B)non-persistent csma
C)p-persistent csma
D)o-persistent csma