Wireless Networking Flashcards
Centrally connects wireless network nodes in the same way that a hub connects wired Ethernet PCs. Many can act as switches and Internet routers
Wireless Access Point (WAP)
Networking scheme used by wireless devices to transmit data while avoiding data collisions, which wireless nodes have difficulty detecting
Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA)
Each wireless node in direct contact with every other node in a decentralized free-for-all. Suited for small groups of computers (less than a dozen or so) that need to transfer files or share printers and for temporary networks such as study groups or business meetings
Ad Hoc Mode/Peer-to-Peer Mode
Two or more wireless nodes communicating in ad hoc mode
Independent Basic Service Set (IBSS)
Use one or more WAPs to connect the wireless network nodes to a wired network segment. Default mode that is better suited to networks that need to share dedicated resources such as Internet connections and centralized databases
Infrastructure Mode
A single WAP servicing a given area
Basic Service Set (BSS)
BSS extended by adding more WAPs
Extended Basic Service Set (EBSS)
Hybrid wireless and wired network. Key characteristic is that the nodes act like routers, forwarding traffic for other nodes, but without the wires
Wireless Mesh Network )m(WMN)
Standard that defines methods devices may use to communicate via spread-spectrum radio waves
IEEE802.11 wireless Ethernet standard/Wi-Fi
Broadcasts in small, discrete chunks over the frequencies available within a certain frequency range
Spread-Spectrum
Two radio bands that the 802.11-based wireless technologies broadcast and receive
2.4GHz and 5GHz
A contiguous range of frequencies that is usually divided up into discrete slices (channels)
Band
Standard that operates in the 5GHz frequency range which means that devices that use the same frequency range. Offer greater throughput than 802.11 and 802.11b at speeds up to 54 Mbps, though its actual throughput is no more than 25 Mbps in normal traffic conditions. Theoretical range tops out at about 150 feet, its max range will be lower in a typical office environment
802.11a
The first standard to take off and become ubiquitous in wireless networking. Supports data throughput of up to 11 Mbps (with actual throughput averaging 4 to 6 Mbps) - on par with older wired 10BaseT networks - and a max range of 300 feet under ideal conditions. Main downside: uses a very popular frequency: 2.4GHz. Likely to run into interference from other wireless devices
802.11b
Takes the best of 802.11a and 802.11b and puts them together. Offers data transfer speeds equivalent to 802.11a with the wider range of 802.11b. Runs in the 2.4 GHz band so it is backwards compatible with 892.11b
802.11g
Standard that brought improvements to Wi-Fi networking, including faster speeds and new antenna tech implementations. Require all but handheld devices to use multiple antennas to implement a feature called MIMO. With up to four antennas, devices can achieve amazing speeds. Supports throughput of up to 600 Mbps although practical implementation drops that down substantially (100+ Mbps at 300+ feet). Uses transmit beamforming. Dual-band so it supports 2.4GHz and 5GHz
802.11n
Enables the devices to make multiple simultaneous connections
Multiple In/Multiple Out (MIMO)
A multiple-antenna technology that helps get rid of dead spots - or at least make them not so bad
Transmit Beamforming
Natural expansion of the 802.11n standard, incorporating even more streams, wider bandwidth, and higher speed. Only uses the 5GHz band but supports dual-band operation (some support tri-band with a second 5GHz band). Uses MU-MIMO
802.11ac
A new version of MIMI that gives a WAP the ability to broadcast to multiple users simultaneously
Multiuser MIMO (MU-MIMO)
Protocol that implements communication through infrared devices. All versions of Windows and pretty much the whole computing industry support this stack as an industry standard. Can transfer data up to 4Mbps with a max distance between infrared devices of 1 meter. Infrared links are direct line of sight and susceptible to interference. Doesn’t have infrastructure mode, only ad hoc. Operates at half-duplex. Offers no encryption or authentication
Infrared Data Association (IrDA) protocol
Designed to create small wireless networks preconfigured to do very specific jobs. Personal area networks (PANs) that link two computers for a quick wireless network and input devices such as keyboard and mice. Uses a broadcasting method that switches between any of the 79 frequencies available in the 2.45 GHz range. Hops frequencies some 1600 times per second, making it highly resistant to interference
Bluetooth wireless technology
Supports speeds around 1Mbps. IEEE made this the basis for its 802.15 standard for wireless PANs
First gen Bluetooth (1.1, 1.2)
Backwards compatible with first gen and adds support for more speed by introducing Enhanced Data Rate (EDR) which pushes top speeds up to around 3Mbps
Second gen Bluetooth (2.0, 2.1)
