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wireless networks have become almost
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commonplace in our homes and businesses
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and we've almost come to expect that
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when we walk into a restaurant or a
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conference room that there will be a
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wireless network available to use the
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standards for these wireless networks
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come from an ieee lan man standards
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committee this is the ieee 802 committee
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and the wireless networking part of this
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committee is the
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802.11 standard but as you're probably
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aware there are many different wireless
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standards and in this video we'll step
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through each one of those 802.11
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standards
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instead of referring to these as 802.11
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wireless networks you'll often see this
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abbreviated as a wi-fi network this is a
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trademark from the wi-fi alliance who's
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responsible for testing the
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interoperability of all of these
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different wireless devices
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the first standard we'll look at is the
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one from the very beginning it's the
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802.11 a this is one of the very first
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wireless standards that was released
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back in october of 1999. it's a standard
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that operates exclusively in the 5
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gigahertz frequency range it can use
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other frequency ranges with special
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licensing although these days you don't
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often see very many
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802.11a networks still around the
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802.11a wireless standard operates at 54
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megabits per second and although this
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doesn't seem very fast now back in 1999
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when this was first released that was a
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great deal of speed on a network that
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suddenly was able to operate wirelessly
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because we are operating at five
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gigahertz frequencies we don't tend to
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have the same range as lower frequencies
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such as the 2.4 gigahertz range that's
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used by 802.11b
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with these higher frequencies the
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objects around us tend to absorb the
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signals whereas with 802.11b
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they tend to bounce off of those devices
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and therefore we get a little bit more
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distance from a 2.4 gigahertz based
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network as i mentioned it's not common
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to see 802.11 a in use these days and
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very often this will be a type of
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network that has already been upgraded
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to a much faster and newer standard
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at about the same time that 802.11a was
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released the ieee also finalized the
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802.11 b standard this is not an upgrade
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to the a instead this is a completely
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different standard that operates with
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different frequencies and different
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speeds 802.11b operates in the 2.4
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gigahertz range and its maximum speed is
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11 megabits per second which is
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certainly much slower than the 54
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megabits per second we were able to get
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with 802.11 a so why would we choose the
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slower 11 megabit per second wireless
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standard when a 54 megabit standard
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already was available in many cases this
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is associated with the frequency in use
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as i mentioned earlier 2.4 gigahertz
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frequencies tend to bounce off of
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devices instead of being absorbed and
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therefore we get a bit longer distance
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in 2.4 gigahertz networks this of course
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will depend on the type of environment
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if you're in a warehouse you may choose
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802.11a because there's so much open
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space but if you're in an office setting
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with a lot of people and desks you may
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choose 802.11b because that frequency
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works a lot better in that environment
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one challenge we have with this 2.4
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gigahertz range is that wireless
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networks are not the only devices that
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can use those frequencies it's very
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common to see things like baby monitors
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cordless phones or even the bluetooth
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standard take advantage of 2.4 gigahertz
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frequencies this means that we could
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have frequency conflicts when trying to
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communicate using all of these devices
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simultaneously in one single area it's
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also difficult to find 802.11b networks
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that might still be operating and if you
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do run into an 802.11b network it's
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probably because you're upgrading it to
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a newer version
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one of the first upgrades available to
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these 802.11b networks was the standard
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for 802.11g
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this was released in the june 2003 time
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frame and just like 802.11b 802.11g also
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operates in the 2.4 gigahertz range the
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reason that this was such a useful
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upgrade for folks running 802.11b
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was that we increased the speed on the g
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standard to 54 megabits per second which
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is about the same as we found with
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802.11 a this 802.11 g standard is
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backwards compatible with the b standard
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that means that we could upgrade our
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access point to the 802.11g
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and still continue to use our b devices
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on the same network and although 802.11g
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operates at higher speeds it still
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suffers from the same frequency
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conflicts that we have with the 802.11b
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because all of these devices will be
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using 2.4 gigahertz frequencies
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in 2009 a new standard was released that
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effectively upgraded 802.11 a b and g to
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a new version of
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802.11 in
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as you probably noticed it can be
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confusing to keep track of all of these
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different letters and numbers so instead
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of using the standard name of 802.11a or
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802.11g
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we're now referring to these standards
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as wi-fi standards so 802.11 in can also
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be called y54 technically speaking
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802.11 a b and g could also be called
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wi-fi one two or three but because those
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standards are so old and indeed
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difficult to find implemented on
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anyone's networks these days we are
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starting with wi-fi for as the standards
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for this numbering scheme because
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802.11n or y54 is designed to upgrade
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802.11 a b and g this standard is able
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to operate at both 5 gigahertz and 2.4
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gigahertz simultaneously if your access
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point supports that we also have more
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bandwidth available for each individual
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channel we can have up to 40 megahertz
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channel widths and what this really
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means is we're able to transfer much
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more data at the same time over this
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network if you do have a wireless access
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point that's able to use those 40
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megahertz channel widths and it has four
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antennas on it you can get a maximum
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theoretical throughput from 802.11 in of
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600 megabits per second which is
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obviously a large improvement over
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802.11 a b or g
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this 802.11 in standard also introduced
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a new form of communication for wireless
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networks called mimo or multiple input
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multiple output this means the devices
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can transfer much more information
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simultaneously between the in station
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and the access point
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in january of 2014 we introduced 802.11
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ac which we now refer to as wi-fi five
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and this was another improvement over
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the previous standard of 802.11 in wi-fi
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five operates exclusively in the five
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gigahertz range so unlike 802.11n
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there is no 2.4 gigahertz available in
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wi-fi 5. we can also use much more of
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that wireless spectrum simultaneously
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because 802.11 ac will support up to 160
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megahertz of a channel bandwidth
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this translates into more channels that
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can be used simultaneously and therefore
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more data that can be transferred over
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that wireless network simultaneously
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this standard also changes how
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information is transferred over that
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wireless network we refer to this as
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signaling modulation and this also
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increased the amount of data that was
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able to be transferred at any particular
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time this newer 802.11 ac standard not
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only uses multiple input multiple output
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but increases the capabilities of that
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mimo by adding multi-user mimo so
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multiple users could be communicating
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over multiple input and multiple outputs
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simultaneously this standard supports up
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to eight of those multi-user mimo
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streams which translates into a maximum
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total throughput of nearly seven
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gigabits per second for 802.11 ac
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we mentioned earlier that 802.11 ac
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operates only in the 5 gigahertz band
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but if you look at access points that
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may be available to buy you'll see some
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of them say that they are 802.11 ac
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access points that operate at 5
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gigahertz and 2.4 gigahertz in those
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cases the communication that's occurring
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at 2.4 gigahertz is actually using the
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802.11 in standard and anything at 5
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gigahertz is using the ac standard
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the upgrade to 802.11 ac arrived in
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february of 2021 with the 802.11 ax
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standard or what we call the wi-fi 6
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standard this is a standard that
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operates at either 5 gigahertz
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frequencies or 2.4 gigahertz frequencies
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and on some access points can use both
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of those simultaneously this standard
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also supports many different channel
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widths so we can have bandwidths of 20
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40 80 and 160 megahertz for people
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communicating on that wireless network
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if we look at the standards for 802.11
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ax we can get a total throughput per
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channel of about 1.2 gigabits per second
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this is a relatively small increase in
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throughput when you compare it to other
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improvements in the standards through
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the years but there is a difference in
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how this particular version was designed
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802.11 ax was designed to solve some of
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the problems we have with using these
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wireless networks in areas where there
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are a large number of people so if
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you're at a sporting event or a trade
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show you may find it difficult sometimes
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to communicate over these wireless
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networks with 802.11ax we introduced a
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new form of communicating called
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orthogonal frequency division multiple
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access or
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ofdma this takes a type of communication
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that we've used for some time on our
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cellular networks and brings it into the
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world of 802.11
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this allows us to put 802.11ax networks
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in places with large numbers of people
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and be able to communicate without a
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huge loss in efficiency over those
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wireless networks
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so here's the summary of these different
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standards 802.11a operated on five
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gigahertz frequencies and did not have
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mimo support its maximum theoretical
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throughput per stream was 54 megabits
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per second and in the case of 802.11a we
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only had one stream to work with so we
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had a maximum throughput of 54 megabits
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per second 802.11b operated in the 2.4
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gigahertz range and it operated at a
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maximum throughput at 11 megabits per
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second as the upgrade to 802.11b 802.11g
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also operated at 2.4 gigahertz and had a
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maximum throughput of 54 megabits per
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second if you run into an 802.11 in
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network it can operate at either 5 or
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2.4 gigahertz frequency ranges and can
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use up to four separate streams of
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multiple input and multiple output this
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gives us a total throughput per stream
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of 150 megabits per second or a maximum
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throughput of 600 megabits per second
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overall 802.11 ac is a 5 gigahertz
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technology only it supports eight
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downloadable streams of multi-user
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multi-input multi-output at
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867 megabits per second for each stream
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making a total theoretical throughput
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maximum of 6.9 gigabits per second and
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802.11 ax operates at both 5 gigahertz
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and 2.4 gigahertz it also supports eight
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streams but the multi-user mimo in ax
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supports eight download and upload
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streams simultaneously that gives us a
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maximum theoretical throughput per
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stream of 1.2 gigabits per second any
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maximum theoretical throughput of all
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streams at 9.6 gigabits per second
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if you purchase an access point bring it
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home and plug it in you'll probably get
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a range of about 40 to 50 meters if
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you're using the built-in antennas if
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you're working in a corporate
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environment and you want to connect two
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buildings together with 802.11 then
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obviously that type of antenna is not
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going to work instead you'll need some
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fixed directional antennas and you may
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need to increase the overall signal
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strength of the 802.11 signal
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in our offices and homes we have signals
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that might be bouncing or be absorbed by
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the things around us when we're sending
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a signal between buildings there's
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usually not much in the way that would
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cause the signal to bounce or be
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absorbed we would use very directional
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antennas like this yagi antenna to be
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able to have a very focused
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point-to-point connection between an
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antenna on one building and the antenna
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on the other building if you're planning
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to set up a long-range fix wireless
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network make sure you look at the rules
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and regulations in your area wireless
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networks have their own complexities
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associated with them and when you layer
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on local and federal rules and
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regulations regarding wireless
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communication it provides some
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additional challenges to the
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implementation if you're using a
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wireless service that's transmitting to
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your home or you're trying to connect
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different wireless services between
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buildings you may want to look to see
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what frequencies are available to use
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you may have 2.45 gigahertz frequencies
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available natively in the standard but
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there may be other frequencies available
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that you can apply for which might
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provide you some advantages over using
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the busier 2.4 gigahertz or 5 gigahertz
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frequencies you'll need to check with
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the 802.11 standards and see what
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options might be available for the type
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of network that you're installing
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not only are there rules and regulations
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about what frequencies you can use and
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where you can use them there are also
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regulations about how much of the signal
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can be sent there are different
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regulations on whether these signals
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will be inside of the building or
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outside of the building so make sure you
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know all of the differences when you're
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installing the network
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and ultimately you'll need to install an
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antenna outside if you're receiving a
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signal from a service provider or you're
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connecting two buildings together
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installing antennas outside have their
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own set of safety requirements not only
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in where you install the antenna and
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that it's not near any power source but
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you also have to make sure that the
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antenna is protected in case it happens
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to be hit by lightning in many cases it
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might make more sense to bring in a
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third party who has an expertise
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installing these types of external or
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outdoor networks
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another wireless technology that's
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widely used is rfid or radio frequency
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identification if you have an access
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badge that unlocks a door by holding it
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up to a sensor it's probably using rfid
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inside of that badge if you're in
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manufacturing and you have an assembly
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line or you need to keep track of
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inventory then you will extensively use
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rfid and we even use rfid at home to
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keep track of our pets so if we happen
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to lose that pet they can easily be
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scanned and that identification
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information will be tied back to you so
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that your pet can be returned this is
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one type of rfid tag you can see this
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one is designed to be cylindrical and
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you can see how small it is because it's
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next to this grain of rice
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if you have an rfid tag inside of your
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access badge and it's probably a flat
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one like this where the antenna is
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around the outside and the rfid chip is
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right in the middle
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as you can see in these pictures there's
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often no battery inside of these rfid
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tags instead this uses radar technology
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as we send signals out that signal is
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being captured by the antenna that is
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converted to power added to the chip
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that effectively powers and allows this
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device to transmit back
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although this is one way to communicate
00:16:03
via rfid there are other rfid tags that
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do have a power source we refer to those
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as active or powered rfid
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we've extended the use of rfid into our
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mobile phones and our smart watches
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through the use of nfc this is near
00:16:20
field communication and it's a way for
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our mobile devices to be able to have
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two-way conversations with other devices
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that we might use for example we might
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be checking out at a store and we can
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use our phone or our smart watch to pay
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for those goods because we've associated
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our credit card with the nfc technology
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that's in our devices
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you might also see nfc used if you need
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to pair two bluetooth devices and
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because we often carry our phones and
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our smart watches with us we can use nfc
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to act as an access card so that we can
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use our phone to unlock a door instead
00:16:56
of a separate card
00:17:07
you
