Wireless Networking and 802.11 WiFi standards Flashcards
Which wireless frequency, 2.4GHz or 5GHz has longer transmitting RANGE? And which has a better maximum data transfer rate/speed?
2.4GHz wireless frequency has a longer range but lower data transfer rate/less Mbit/s. This is because higher frequencies (like 5GHz) tend to get absorbed by materials instead of bouncing off of them.
802.11b operates on a 2.4Ghz frequency with a maximum throughput of 11Mbit/s.
In an open field would it be better to have an 802.11b or an 802.11a WiFi standard? And why?
In an open field/empty room it makes more sense to use an 802.11a standard router as the maximum throughput is higher than that of the 802.11b standard.
The advantage that the 802.11b standard has over the 802.11a is range but it only has this because it’s signal is less absorbed by materials, such as desks, carpeting but is a non issue in an open space.
However, it’s rare to see 802.11b/802.11a today as they’re outdated and there are upgrades available such as 802.11g which is backwards compatible with 802.11b but has higher speed/better bandwidth - the speed of a + the range of b = a true standard g
From the 4th version of the 802.11 standard (802.11n) Wifi Standards are being numbered instead of using letters. If 802.11a, 802.11b and 802.11g were numbered (in order of their release) which WiFi version numbers would they be respectively?
802.11a would be WiFi 1 as it was the earliest version.
802.11b would be WiFi 2.
802.11g as it was the most recently released version before the advent of WiFi 4/802.11n.
Which WiFi standard was the first version to operate at both 5 GHz and 2.4Ghz simultaneously (assuming Access Point supports that)?
802.11n aka WiFi-4 was the first version/standard (2009) of the 802.11 LAN technical standards that supports simultaneous 5GHz and 2.4GHz transmission.
It was also the first standard to introduce/use Single User MIMO - Multiple Input/Multiple Output which meant that by having multiple receiving and transmitting antennas the device could transfer much more information simultaneously.
How many WiFi - versions are there now? Try to list them in order of release and detail as much about them as you can.
There are 6 Wifi- Versions currently and they are (in order of introduction/release):
WiFi-1 - 802.11a - 5GHz 54Mbit/s (bandwidth - per channel maximum throughput)
WiFi-2 - 802.11b - 2.4GHz 11Mbit/s - B for better range than A, but lower bandwidth
WiFi-3 - 802.11g - 2.4GHz 54Mbit/s - same range as B (as low frequency 2.4) but same bandwidth as A. A+B = G
WiFi-4 - 802.11n - supports both 2.4GHz and 5GHz bands - introduced Single User (SU) MIMO (Multiple Input/Multiple Output to one device at a time - via multiple receiving and transmitting antennas to improve transfer rates)
WiFi-5 - 802.11ac - 5 GHz frequencies only - introduced MU-MIMO (Multi-User MIMO to support multiple users (up to 8) to benefit from and use MIMO simultaneously) Maximum throughput of 7Gbit/s.
WiFi-6 - 802.11ax - 5 or 2.4 frequencies. OFDMA - Orthogonal Frequency-Division Multiple Access (works like cellular communication) - good for supporting a TONNE of users at once e.g. at a sporting event.
Does a higher (5GHz) or lower frequency (2.4GHz) WiFi range have a higher chance of conflicting with other wireless devices such as Bluetooth devices and microwave overs?
The lower frequencies in the 2.4GHz range are more likely to run into frequency conflicts with the given devices because Bluetooth and other devices tend to run within this range.
What is frequency conflict in wireless networking?
Frequency conflict refers to wireless networks in the same range competing/clashing with each other. This reduces signal strength of both/all devices in the range.
It generally occurs more at 2.4GHz frequencies as a lot of other devices use those ranges (e.g. Bluetooth, microwaves).
Which 802.11 networking standard was the first to operate at both 5GHz and 2.4GHz frequencies SIMULTANEOUSLY (assuming the device supported it)?
802.11n (WiFi-4) was the first standard to use both frequencies simultaneously.
Released in 2009 the n standard was a big upgrade to the a, b and g standards.
It was also the first to support SU-MIMO via multiple antennae.
What does MIMO stand for and what does it mean for WiFi bandwidth? Which IEEE WiFi standard was the first to support it?
Multiple Input Multiple Output is a way of using multiple transmitting and receiving antennas on a device to transfer more data over the network simultaneously. This effectively increases the bandwidth of the network significantly.
It was first used by the 802.11n standard also known as Wi-Fi 4. Released in 2009 as an upgrade to the a, b and g standards (versions).
3 antennas sending and receiving data from one device to another complete the transmission a lot faster than one antenna would.
Which WiFi standard was released in 2014? Which frequency band (range of frequencies) does it operate on?
802.11ac was released in 2014 also known as WiFi-5 and operates solely in the 5GHz frequency band.
Up to 160MHz channel bandwidth (range of channels) - more channels = bigger bandwidth.
What is MU-MIMO and which WiFi standard/s support it?
Multi-User Multiple-Input/Multiple-Output allows multiple users (up to 8) to SIMULTANEOUSLY use the enhanced transfer speeds of MIMO technology.
It is supported in 802.11ac and 802.11ax WiFi standards. WiFi-5 and WiFi-6.
Which is the only 802.11 WiFi standard to use OFDMA - Orthogonal Frequency Division Multiple Access and what is it good for?
802.11ax is the standard that uses OFDMA which works like cellular communication to make a wifi network efficient when a LOT of users are simultaneously using it, for example at a sporting event, or business conference.
axE standard used for dividing/chopping up wifi across a lot of concurrent users.
What is the maximum speed of wireless standard 802.11n?
600Mbps n.
Maximum speed of 802.11ac?
Up to 1Gbps - AC = 1 Gbps
