Week 5 - Wireless Networking Flashcards
What’s a frequency band?
range of frequencies that are agreed to be used for certain communications
What frequency do FM radio transmission operate in NA?
FM radio transmissions operate at 88-108 MHz in North America
What is a FM broadcast band?
An FM broadcast band is the radio frequency range that the broadcast operates at
What 2 broadcast bands do wireless networks operate on?
2.4 GHz
5 GHz
What layers does the 802.11 standard define how we operate?
802.11 standards define how we operate on the Data Link and Physical layers
What is WAP and how is it defined?
Wireless Access Point
a networking device that allows wireless-capable devices to connect to a wired network
What is used to make sure that incoming transmissions are sent to the right WAP?
Network devices connected to the closest WAP make sure transmissions are sent to the right WAP
What is a receiver address in a 802.11 frame?
A receiver address is the MAC address intended to receive data
What’s a transmitter address in a 802.11 frame? What is it usually the same as?
A transmitter address is the MAC address of where the data was transmitted from
Transmitter address is usually the same as a Source address, depending
What type of addresses are the addresses in an 802.11 frame?
MAC addresses
What are the 6 parts to an 802.11 frame?
- Frame/control (how frame should be processed)
- Duration (how long it is and should listen to it)
- Address 1-4
- Sequence Control (frame order)
- Data payload
- FCS - checksum for CRC like Ethernet does
What are channels when used by a wireless network?
The individual, smaller sections of a frequency band
The specific ranges of microwave and radio frequencies
(highway lanes)
Which Wi-Fi frequency can pass through walls more easily?
2.4 GHz
Which WiFi frequency has the longest range? What is it?
2.4 GHz has the longest range - 150 feet indoors to 300 feet outdoors
How many channels does a 2.4 GHz wifi connection typically have?
11-14 (not as much as 5 GHz)
What can cause interference on the 2.4 GHz frequency?
Microwave ovens, bluetooth and other technology that overlaps that frequency band
What’s the maximum achievable data rate for 2.4 GHz wifi?
600 Mbps
Which Wifi frequency experiences less network interference and congestion?
5 GHz bc it operates on a different frequency band
What’s the wireless range of the 5 GHz frequency?
50 feet indoors, 100 feet outdoors
What is “infrastructure mode”?
client devices that are configured to connect to WAP
What type of traffic can an Access Point serve?
Wired and wireless
For wired the WAP is a bridge between wireless devices and the wired network
How does the AP connect to the network?
Through an Ethernet cable to an Ethernet switch
How do the different 802.11 standards differ? 5
ranges, channels, modulation techniques, transmission bit rates, frequency bands
What prevents 5 GHz radio frequencies from interfering with local radar and satellite communications?
A technology is used called Dynamic Frequency Selection (DFS)
What are the wider bonded channel size for 802.11ac?
80 and 160 MHz
How wide were the channels for the first 802.11a (1999) - Wi-Fi 2 specification?
20 MHz wide
802.11n allowed channel bonding for 5 GHz? What is that?
Channel bonding is when 2 adjacent channels can be combined
What does “dual band” mean?
A separate radio for each band (frequency)
What are the two common data protocol models that show how IoT share data?
- Request/Response
- Publish/Subscribe
What is the Request/Response protocol for IoT data transfer?
The Request/Response protocol is used for communications where servers/clients request and respond with data
Explain what the Publish/Subscribe model is?
The Publish/Subscribe model is for subscribers to a channel who receive new messages from a publisher through a broker.
What are some ways IoT devices collect data around their environment? 3
- Physical location (temperature)
- Metered data like electricity usage
- Equipment data (maintenance status)
Why are data protocols needed for IoT devices?
so applications can receive and format data that humans and automated systems use