L5 Flashcards
What does OSI represent? What are the seven layers of OSI?
how computers are connected
Open Systems Interconnection
Application, presentation, session, transport, network, data link and physical layer
Why can’t IoT use the OSI stack? What is the IoT stack?
IOT stack is different from OSI stack because OSI stack assumes single technology stacks but IoT is characterized by high technology heterogeneity
Application
transport (ensures consistency when communication crosses different networking environments)
network/IP (provides identification functionalities)
link (considers how addressing is being done)
physical (needs to guarantee interoperability)
What is the difference between constrained and unconstrained networks?
Unconstrained networks: high-speed communication links (wired Internet)
Constrained networks: feature low transfer rates
Explain the communication approach for the Internet.
Constrained networks intermediated by an unconstrained network (most typical case)
What is the common antenna type?
The physical size of the antenna should be 1/4 of the signal.
Signals propagate at the speed of light. What is the formula for this?
C (speed of light = 3*10^8) = f (signal frequency Hz) * lambda (wavelength m)
What is the ISM frequency band?
o ISM frequency band is at 2.4 GHz
- More recently another ISM band has been allocated at 5 GHz for unlicensed use
How are baseband signals propagated for a basic communication mechanism?
by modulating higher frequency signals
What is the metric for communication power/quality? What is the formula for it?
deciBell (dB) is commonly used to describe the power of various features of communication systems
dB = 10 log 10 (P1 / P0)
For the deciBell calculation, what is the ratio unit if P0 is 1W and if P0 is 10^-3W?
If P0 = 1W, then the ratio is in dBW
If P0 = 10^-3W, then the ratio is In dBm
Calculate the dBW and dBm for P1 = 100.
dbW = 20 and dBm = 50
How to convert dBW to dBm?
Add 30 to the dBw
If dBW is 10, then dBm is 40.
What is the dBw for 10,000? What is the dBw for 0.0001?
40, then dBm is 70
-40, then dBm is -10
