Wireless Network Technologies

Question 1

802.11 technologies

Answer 1

• frequency
• 2.4 GHz or 5 Ghz (& sometimes both)
• sometimes a ditional bands
• channels-sections of frequencies
• groups of frequencies, numbered by the IEEE
• non-overalpping channels would be necessary
• bandwidth-ranges of frequencies are dependant on the channel width
• amount of frequency in use
• 20 MHz, 40 MHz, 80 Mhz, 160 MHz

Question 2

Band selection & bandwidth

Answer 2

• 2.4 GHz spectrum for 802.11 North America
• 3 non-overlapping channels available (1, 6, 11)
• channels are grouped in 20 Mhz

*5 Ghz Spectrum for 802.1 North America

Question 3

802.11 channel bandwidths & bonding

Answer 3

• 802.11a (20 MHz)
• 802.11b (22 MHz)
• 802.11g (20 MHz)
• 802.11n
• 20 MHz, 40 MHz, 80 MHz
• increase abndwidth with bonded channels
• in 2.4 Ghz, aof 40 MHz channel uses 80% of the available bandwidth
• 802.11ac
• 20 MHz, 40 Mhz, 80 MHz, 80+80 MHz, 160 MHz
• 40 MHz for 802.11n stations, 8- MHz required for 802,11ac sttions
• `60 MHz optional (contiguous bonded channels)
• 802.11ax
• 20 MHz, 40 Mhz, 80 MHz, 80+80 MHz, 160 MHz
• similar bandwidth to 802.11ac

Question 4

Independent basic service set (IBSS)

Answer 4

• two devices communicate directly to each other using 802.11
• no access point required
• Ad hoc
• created for a particular purpoe without any previous planning
• without an AP
• temporary or lomg-term comunication
• connect to a device with an ad hoc connection
• configure it with the access point settings & credentials

Question 5

SSID & BSSID

Answer 5

• every wireless network needs a name
• SSID (Service Set Identifier)
• There might be muliple access points supporting an SSID
• how does your computer tell them apart?
• the hardware address of an access point is a BSSID (basic service set indetifer)
• the MAC (Media Access Control) address

Question 6

Extending the network

Answer 6

• most organizations have more than one access point
• tens or hundreds
• wireless network names can be used across access points
• makes it easier to roam from one part of the network to another
• the network name shared accross access points is an ESSID
• extended service set identifer
• your device automatically roams when moving between access points
• you dont have to manually reconnect

Question 7

Counting antennas

Answer 7

• new technologies were added to 802.11n, 802.11ac & 802.11ax
• send multiple streams of information over the same frequency at the same time
• 802.11n - MIMO (Multiple Input & Multiple Output)
• 802.11ac - downstream MU-MIMO (Multi-user MIMO)
• 802.11ax-downstream and upstream MU-MIMO

*to be able to send & receive information simultaneously we need to have the power number of antennas & support the proper number of streams

• number of antennas (802.11n, 802.11ac, 802.11ax)
• used to determine the nuber of available streams
• (antennas on the access point) X (antennas on the client) : number of streams
• 2X2:2, 3X3:2, 4X4:4

Question 8

Omnidirectional antennas

Answer 8

• one of the most common
• included on most access points
• signal is evenly distributed on all sides
• omni=all
• good choice for most environment
• you need coverage in all directions

*no ability to focus the signal-a different antenna will be required

Question 9

Directional antennas

Answer 9

• Focus the signal
• increased distances
• send & receive in a single durection
• focused transmission & listening
• antenna performance is measured in dB
• double power every 3dB of gain
• Yagi antenna
• very direvtional & high gain
• parabolic antenna
• send info over a longer distance
• focus the signal to a single point

Question 10

Bluetooth

Answer 10

• high spped communication over short distances
• PAN (personal area network)
• connects our mobile devices
• smartphones
• tethrering & file transfers
• headsets & headphones
• health monitors
• automobile & phone integration
• smartwatches
• external speakers

Question 11

Near field communication (NFC)

Answer 11

• two-way wireless communcation
• builds on RFID, which is mostly one way
• payment systems
• major credit cards
• online wallet
• bootstrap for other wireless
• NFc helps with bluetooth pairing
• access token, identity card
• short range with encryption support

Question 12

RFID (Radio-frequnecy identification

Answer 12

*it’s ecerywhere
-access badges
-inventory/ assembly line tracking
pet identification
-anything that needs to be tracked

• radar technology
• radio energy transmitted to the tag
• RF powers the tag, ID is transmitted back
• bidirectional communication
• some tag formats can be active/powered

Question 13

Zigbee

Answer 13

• Internet of Things networking
• open standard - IEEE 802.15.4 PAN
• Alternative to WiFi & bluetooth
• longer distances than bluetooth
• less power consumption than wifi
• mesh network of all zigbee devices in your home
• light switch communicates to light bulbs
• tell amazon echo to look door
• uses the ISM band
• industrial, scientific & medical
• 900 MHz & 2.6 GHz frequencies in the US

Question 14

Z-Wave

Answer 14

• Proprietary home automation networking
• Internet of Things (IoT)
• control lights, locks, garage doors
• wireless mesh networking
• nodes can hop thru other nodes on the way to the destimation
• uses the ISM band
• industrial, scientific & medica
• 900 MHz frequwncies in the US
• no conflicts with 802.11