Advanced Networking

Question 1

What year was Bluetooth version 1 released?

Answer 1

Bluetooth version 1 was released in 1999

Question 2

What is the name of the organization that founded bluetooth, currently owns the Bluetooth trademark, controls bluetooth research and development and license marketing?

Answer 2

Bluetooth Special Interest Group (SIG)

Question 3

What band frequency(i.e., GHz) does bluetooth operate?

Answer 3

Bluetooth operates at 2.4ghz

Question 4

What ways can you avoid interference with Wi-Fi?

Answer 4

To avoid interference in WiFi you can implement

Time Division Multiplexing

or

5GHz Wi-Fi

Question 5

What frequency-shift keying filter algorithm does bluetooth use?

Answer 5

Bluetooth uses Gauassian Filter and Differential filter

Question 6

What are some challenges of RF communication under water?

Answer 6

Battery power is limited and usually batteries can not be recharged because solar energy cannot be exploited.
The available bandwidth is severely limited.
Channel characteristics, including long and variable propagation delays, multi-path and fading problems.
High bit error rates.
Underwater sensors are prone to failures because of fouling, corrosion, etc.

Question 7

What is the generic idea of Underwater Acoustic Sensor Network (UWASN)?

Answer 7

Multiple sensor nodes are needed to raise information rates and have short-range communication, resulting in excellent coverage

Question 8

Describe DSRC channel allocation

Answer 8

Channel 172 designated for V2V safety of life
Channel 184 designated higher power for public safety

Dedicated short-range communications (DSRC) band allocated by FCC: 5.850-5.925 GHz: Seven 10-MHz channels
Seven 10 MHz channels in 5.9 GHz band
Channel 178 used as Control Channel (CCH)
Channels 174, 176, 180, 182 used as service channels (SCH)
Channel 184 is reserved for future High Availability Low Latency (HALL)
Channel 172 is unused
Different EIRP for 4 Classes:
A/B: 23 dBm, C:33 dBm, D: 43dBm (Govt), 33 dBm (others)

Question 9

Describe the WSMP message header

Answer 9

WAVE Short Message Protocol

Question 10

Between DSRC and the emerging 5G technologies, which do you think will “win” in the automotive industry for V2X communications?

Answer 10

I think 5G will win because most people will have 5G technology available. The reason I think DSRC won’t win is because it is designed for short range communication, which means it is good for cities but long-range communication is needed on highways using cellular technology.

Question 11

What are some security concerns with the emerging 5G technologies?

What are some proposed solutions?

Answer 11

Some 5G threats could be hackers being able to access user locations and attack on devices. This is dangerous especially when it comes to self-driving cars running on 5G because its a life-critical application.

A few solutions would be securing the edge of the network to enable realtime detection capabilities. Allowing the network to find and stop breaches before they make it to the core.

Question 12

Describe the hidden terminal problem

Answer 12

In wireless networking, the hidden node problem or hidden terminal problem occurs when a node can communicate with a wireless access point, but cannot directly communicate with other nodes that are communicating with that AP

Question 13

Describe RTS / CTS Protocol

Answer 13

RTS/CTS (Request To Send / Clear To Send) is the optional mechanism used by the 802.11 wireless networking protocol to reduce frame collisions introduced by the hidden node problem.

Question 14

RTS / CTS Frame Description

Answer 14

The RTS frame contains five fields, which are:

Frame Control
Duration
RA (Receiver Address)
TA (Transmitter Address)
FCS
The CTS frame contains four fields, which are:

Frame Control
Duration
RA (Receiver Address)
FCS

Question 15

Describe Stop and Wait Protocol

Answer 15

It is the simplest flow control method. In this, the sender will send one frame at a time to the receiver. The sender will stop and wait for the acknowledgment from the receiver. This time(i.e. the time between message sending and acknowledgement receiving) is the waiting time for the sender and the sender is totally idle during this time. When the sender gets the acknowledgment(ACK), then it will send the next data packet to the receiver and wait for the acknowledgment again and this process will continue as long as the sender has the data to send

Question 16

Describe Stop and Wait Protocol

Answer 16

The sender sends the packet and waits for the ACK (acknowledgement) of the packet. Once the ACK reaches the sender, it transmits the next packet in row. If the ACK is not received, it re-transmits the previous packet again.

Question 17

Describe Go-back-N

Answer 17

The sender sends N packets which is equal to the window size. Once the entire window is sent, the sender then waits for a cumulative ACK to send more packets. On the receiver end, it receives only in-order packets and discards out-of-order packets. As in case of packet loss, the entire window would be re-transmitted

Question 18

Describe 2-D parity bit check

Answer 18

Parity check bits are calculated for each row, which is equivalent to a simple parity check bit. Parity check bits are also calculated for all columns, then both are sent along with the data. At the receiving end these are compared with the parity bits calculated on the received data

Question 19

Describe Checksum

Answer 19

In checksum error detection scheme, the data is divided into k segments each of m bits.
In the sender’s end the segments are added using 1’s complement arithmetic to get the sum. The sum is complemented to get the checksum.
The checksum segment is sent along with the data segments.
At the receiver’s end, all received segments are added using 1’s complement arithmetic to get the sum. The sum is complemented.
If the result is zero, the received data is accepted; otherwise discarded.

Question 20

Describe CRC

Answer 20

Unlike checksum scheme, which is based on addition, CRC is based on binary division.
In CRC, a sequence of redundant bits, called cyclic redundancy check bits, are appended to the end of data unit so that the resulting data unit becomes exactly divisible by a second, predetermined binary number.
At the destination, the incoming data unit is divided by the same number. If at this step there is no remainder, the data unit is assumed to be correct and is therefore accepted.
A remainder indicates that the data unit has been damaged in transit and therefore must be rejected.

Question 21

Describe Hamming Code

Answer 21

Hamming code is a set of error-correction codes that can be used to detect and correct the errors that can occur when the data is moved or stored from the sender to the receiver.

Question 22

What is EDGE Computing and why is it important for IoT?

Answer 22

Edge computing is a distributed computing paradigm which brings computation and data storage closer to the location where it is needed, to improve response times and save bandwidth