Wireless Networks Flashcards
Direct-Sequence Spead Spectrum (DSSS)
Modulates data over an entire range of frequencies using a series of signals known as chips. Not used very often
Frequency-Hopping Spread Spectrum (FHSS)
Allows devices to hop between predetermined frequencies. Used as a security measure in some networks but has lower speed.
Orthogonal Frequency Division Multiplexing (OFDM)
Uses a slow modulation rate with simultaneous transmissions over 52 different data streams. Gives higher data rate and more resistant to interference
Channel
A virtual medium through which wireless networks can send and receive data. The standard channel size for both 2.4 GHz and 5 GHz networks is 20 MHz
2.4 GHz spectrum
There can be 11, 13, or 14 channels. Channels 1, 6, and 11 avoid overlapping frequencies in the 2.4 GHz band
5.0 GHz spectrum
We can use 5.725 - 5.875 GHz to run our wireless networks in the 5 GHz band. There are 24 non-overlapping channels in the 5 GHz band of 20 MHz each
Channel Bonding
Allows for the creation of a wider channel by merging neighboring channels into one. (ex. combining 8 channels to obtain a 160 MHz channel). Increases the probability or running into interference
For Wireless standards it is EXTREMELY important to memorize the following: (Print a chart of it!)
Standard
Band
Bandwidth
Multiple-Input and Multiple-Output (MIMO)
Uses multiple antennas to send and receive data. The more antennas the more data transfer could be supported simultaneously
Multiple User Multiple Input Multiple Output (MU-MIMO)
Allows multiple users to access the wireless network and access point at the same time
Radio Frequency Interference (RFI)
Occurs when there are similar frequencies to wireless networks in the area
Pre-Shared Key
Both the access point and the client use the same encryption key. It is not a good idea to use pre-shared keys in large environments
Wired Equivalent Privacy (WEP)
Original 802.11 wireless security standard which is an insecure security protocol. WEP uses 24-bit initialization vector (IV) sent in clear text
Wi-fi Protected Access (WPA)
Replaced WEP and follows the Temporal Key Integrity Protocol (TKIP). Uses 48-bit Initialization Vector (IV) instead of 24-bit. Adds Rivest Cipher 4 (RC4) for encryption. Uses Message Integrity Check (MIC) to confirm data was not modified in transit. In Enterprise Mode, it authenticates users before exchanging keys
Wi-fi Protected Access 2 (WPA2)
Created as part of IEEE 802.11i standard and requires stronger encryption and integrity checking through CCMP. CCMP is part of WPA2! Uses Advanced Encryption Standard (AES) to provide additional security by using a 128-bit key or higher
