L13 & L14 Flashcards
What does the “duty cycle” DC parameter in LoRA do?
It heavily regulates the different bands that LoRa can use. It does this by setting the maximum percentage of time during which an end device can occupy a channel.
What are two configurable LoRa parameters?
Spreading Factor (SF): affects communication range
Duty Cycle (DC): regulates the different bands that LoRa can use
What is the difference between the three LoRaWAN devices? Which one should all LoRaWAN implementations support?
Class A: lowest power end-device system as it only requires downlink communication from the server shortly after the end-device has sent an uplink transmission
Class B: opens extra receive windows at scheduled times
Class C: continuously open receive windows, only closed when transmitting
All should support Class A
What is the difference between uplink and downlink in communication in LoRaWAN device classes?
Uplink: end-device to gateway/network server
Downlink: gateway/network server to end-device
How are frames retransmitted in downlink and uplink communication?
Downlink frames: for a ‘confirmed’ downlink, if the ack is not received, the application server is notified and may send a new frame. If the FPending is set, it performs uplink communication even if frames are empty
Uplink frames: Uplink ‘confirmed’ and ‘unconfirmed” frames are transmitted “NbTrans” times except if a valid downlink is received
What is NbTrans in uplink frame retransmission?
“NbTrans” determines how many times a frame is retransmitted (but is the total number of transmissions) and can ensure QoS
What will the NS server respond with to the join or rejoin-request if the ED is permitted to join?
join-accept
What are the two ways of joining a LoRaWAN network?
Over-the-air activation (OTAA)
Activation by personalization (ABP)
Which would you pick: device with low performance, device with antennas, or receiver?
Receiver
What is the relationship with the ToA (time on air) and SF (spreading factor)?
Linear
What causes more losses in unconfirmed packets? What causes more losses in confirmed packets?
More interference
More traffic
