Wireless Networking—NETWORKING ESSENTIALS—CompTIA A+ (220-1001) A-PLUS Certification Prep Course Notes

Wireless Networking

Wireless Network Hardware
- A wireless access point (WAP) bridges 802.11 and Ethernet networks
- Wireless clients connect to WAPs
- 802.11 works in one of two modes:
  - infrastructure mode, or
  - ad hoc mode
- Use correct antenna for the job
- In many of today’s laptops the antenna is built into the laptops monitor itself.
- (SSID)-Service Set Identifier (SSID)

Wi-Fi Standards
- 802.11 uses the 2.4- and 5-GHz ISM band
- 802.11 uses remade channels
- Memorize the band usage and relative speeds of the 802.11 extensions.
- (ISM) Industrial, Scientific, and Medical Radios Bands
  - 2.4 GHz and 5 GHz Band
  - Band is a range of radio frequencies
  - 2.4 GHz Band: 2.412-2.4884 GHz
  - Uses different “channels”
  - 5 GHz Band: 5.150 – 5.875 GHz
  - Also uses different channels
- MIMO (Multiple-Input Multiple-Output)
- 802.11ac
  - Multi-User MIMO
- 802.11n
  - Wi-Fi 4
- 802.11ac
  - Wi-Fi 5

Standard	Speed	Band
802.11a	54 Mbps	5 GHz
802.11b	11 Mbps	2.4 GHz
802.11g	54 Mbps	2.4 GHz (802.11g is backwards compatible with 802.11b 2.4 GHz.)
802.11n	100 Mbps	2.4 GHz & 5 GHz (802.11n is backwards compatible with all the others.)

802.11 Extensions

Basic WAP Setup
- A site survey shows available channels in a ISM band
- You must create a service set identifier (SSID)
- Most WAPs support multiple SSIDs
- You can also hide SSID broadcasts
- You can define extensions to support, channels, and channel width.
- We can use WiFi analyzers to perform a site survey.
  - ex: “WiFiman” from Ubiquity Networks company
- SSID (Service Set Identifier)-“name of the wireless network”

Connecting to a Wi-Fi Network
- All wireless clients can scan the 802.11 spectrum, finding available SSIDs
- You must know the SSID and password to connect
- Clients create profiles that store the SSIDs and their passwords

It’s a Huge Mesh
- Mesh Networks are often a great wireless solution for SOHO environments
- Mesh networks have a base station & beacon devices that connect to the base station
- Mesh networks use their own encryption
- Mesh networks are universally easy to configure.
- WMN (Wireless Mesh Network)

Beyond Wi-Fi
- RFID uses tiny radios activated by the energy of the scanning device
- NFC requires extremely close proximity to function
- Bluetooth is like 802.11 but pairs with devices to function as point-to-point.
- RFID (Radio Frequency Identification)
- NFC (Near Field Communication) NFC is RFID.
  - used to “Tap to print” functions or “Tap to pay”
- PAN (Personal Area Network)—Bluetooth
- Bluetooth classes
  - Class —> Power —> Range
  - Class 1 —> 100mW —> 100m
  - Class 2 —> 2.5mW —> 10m
  - Class 3 —> 1mW —> 1m

Troubleshooting Wireless Connections
- The CompTIA A+ exams list specific wireless errors
- Wi-Fi analyzers are very helpful to diagnose wireless problems