802.11

Wireless Setup Modes

  • Ad hoc

    • point-to-point network

    • system connects directly to another system

  • Infrastructure

    • Use an Access Point (AP) to funnel all wireless connections through

    • Wireless devices are usually on completely different subnets than wired clients

    • Client needs to associate with an AP and then disassociate when it moves to the next one

Wireless Terms

  • Basic Service Area (BSA) - The footprint when you have a single access point

  • Basic Service Set (BSS) - Communication between a single AP and its client

  • Extended Service Set (ESS) - Extend the range of your network by adding multiple access points

  • Roaming - Movement across multiple APs within a single ESS

  • BSSID - The MAC address of the wireless access point that is at the center of your BSS

  • Association - action of a client connecting to an AP

  • Authentication - actually identifies the client before it can access anything on the network

Wireless Standards

Wireless Standard
Operating Speed (Mbps)
Frequency (GHz)
Modulation Type

802.11a

54

5

OFDM

802.11b

11

2.4

DSSS

802.11d

Variation of a and b standards for global use

802.11e

QoS initiative providing guidance for data and voice prioritization

802.11g

54

2.4

OFDM and DSSS

802.11i

WPA/WPA2 encryption standards

802.11n

100+

2.4-5

OFDM

802.11ac

1000

5

QAM (Quadrature Amplitude Modulation)

Orthogonal Frequency-Division Multiplexing (OFDM)

  • Several waveforms simultaneously carry messages back and forth

  • Transmission media is divided into a series of frequency bands that don't overlap each other

Direct-Sequence Spread Spectrum (DSSS)

  • Combines all the available waveforms into a single purpose

  • Entire frequency bandwidth can be used at once for the delivery of a message

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