As part of our wireless designs, we might find that an organization desires to
see the deployment of real-time location services, which Cisco abbreviates as
RTLS. Real-time location services are RTLS. This is the desire for us to track
wireless devices and potentially keep a historical record over time as far as
where they went. So we can start to look at things such as foot traffic. There WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
where they went. So we can start to look at things such as foot traffic. There
might be a retail store that wants to track, "Hey, where are users or customers
at
that point going?" So if they have a wireless device in their pocket and they
're
walking around, we can kind of track, "Hey, which of those aisles do they go
down
the most? Which do they go down the least?" and try to figure out maybe an
optimal
way of organizing their inventory. We can also track missing devices. This is
something that has made its way into the residential world. A lot of our WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
something that has made its way into the residential world. A lot of our
mobile devices have kind of that "find my phone" feature and we'll hopefully
track it down potentially using the cellular network, but some devices will
use Bluetooth or Wi-Fi as well to help us locate them. We can also use the
concept of geo-fencing, sort of creating a virtual fence for devices that they
're
not allowed to cross. So for example, we might have a hospital and they've got
this hospital premise and then they've got the parking lot out here and they WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
this hospital premise and then they've got the parking lot out here and they
start to tag, add sensors to things like wheelchairs. So if a wheelchair goes
out into the parking lot, well, it has crossed this virtual threshold that is
built
around the hospital and it will flag an admin to say that, "Hey, there's a
wheelchair
out here." Wheelchairs are not supposed to go out to the parking lot because
they
might get packed up into somebody's car and they take it home. Furthermore,
there
might be blood pumps that, you know, IVs, IV pumps, that we're trying to figure WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
might be blood pumps that, you know, IVs, IV pumps, that we're trying to figure
out
where they are. We don't know where they are. Well, now an admin can pull up a
map and very quickly find it. So that would maybe fall more under the missing
devices, but hospitals take heavy advantage of real-time location services, at
least in my experience. So how exactly does location work? I mean, can we just
do
it on any old wireless network? And as you might imagine, the answer is no. We
do
have to design the wireless network to support location services. Just like WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
have to design the wireless network to support location services. Just like
with
real-time applications that we mentioned earlier, if I am deploying a data
network, it's not necessarily going to support voice over IP. Same thing here.
I
might create a design and it doesn't actually support real-time location
services. So to understand how our designs have to be adapted helps to
understand
how exactly location works. So at a high level, we want to talk about our
location tracking methods. And there are a few to keep in mind. Now the first WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
location tracking methods. And there are a few to keep in mind. Now the first
one to talk about is triangulation. It's one that often gets cited. It's
certainly the basis for basic location services, but at the same time it's not
actually the best technique. But yeah, let's just start here. So the idea here
is how can I track where device is? Well, if I have an access point here and I
'll
just star the access point. I've got a wireless station out here. I might see WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
just star the access point. I've got a wireless station out here. I might see
that this station has a signal strength of -75 dBm. So cool. I hear on my
diagram
I can see that it's right there relative to the access point. Except not really
because if I think about that signal as being around the AP, it could have a
-75 signal down here. It could have a -75 signal over here. It could be WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
-75 signal down here. It could have a -75 signal over here. It could be
anywhere
on that circle. And so that only tells me about where it is. I mean it's
helpful to
know that it's somewhere within the radius of this access point. This access
point can see it. Maybe this access point over here can see it. That can be
helpful, but it's not high accuracy location. And so from here what we'll say
is
let's compare it to another access point. So now this access point also sees
this
device and maybe it sees it at, you know, this is -75, but this access point WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
device and maybe it sees it at, you know, this is -75, but this access point
over
here sees it at -78. So again we can kind of figure out that it's probably
somewhere in this area. But again not highly accurate, not pinpointing where
the
device is. But now we add a third access point in here and I draw a circle
around
it because it sees it at -72. And now we're starting to get very highly
accurate.
I can say, okay, it's probably right in this area based on these three APs WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
I can say, okay, it's probably right in this area based on these three APs
seeing
it at their specific signal strength levels. We call it triangulation because
it
forms this triangle. That was a really bad attempt at a triangle. And we as
long as
the device is somewhere inside of this triangle of access points in theory, we
are able to figure out where exactly that AP is. Here's the problem with this
technique. What if we have a very thick wall here? Well this access point might WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
technique. What if we have a very thick wall here? Well this access point might
say, okay, you're at -75, but the device is not this far away. It's actually
right
here against the wall. And as we add in more devices and or more obstacles to
our
wireless devices, it gets trickier and trickier to use this technique. Now in a
lot of cases, we could say, well, let's add a fourth access point in the more
APs
that we have, the better off we are at comparing the different signals. But WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
that we have, the better off we are at comparing the different signals. But
this is
not considered to be a high accuracy method because it relies entirely on
signal strength. And signal strength is disrupted by obstacles. It depends on a
lot of factors that can make it so it's not high accuracy. So what if we want
better accuracy? What techniques do we use? Well there are several here. We're
not
going to go into the details of them, but let's understand sort of the concept WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
going to go into the details of them, but let's understand sort of the concept
behind them. So for example, we have the concept of time of arrival. And we
also
have a time of arrival that is a slight variation of this, which is the time
difference of arrival. And lastly, we have angle of arrival. So these are
typically abbreviated as T O A, T D O A and A O A. So we've got three different WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
typically abbreviated as T O A, T D O A and A O A. So we've got three different
techniques that we typically deploy to help us out with this. And essentially
what
we're trying to do is remove signal strength or that R SSI as we called it
we're trying to remove signal strength from the equation. We don't want to rely
on
signal strength because it gets disrupted. What doesn't get disrupted is the
speed
of light as well as the trajectory in a lot of cases. And so what we can do is WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
of light as well as the trajectory in a lot of cases. And so what we can do is
say
okay, well I received this signal at a particular time and you received the
signal at a particular time. And now we can compare those time and say well we
know what the speed of light is. So we know about how far away it is from each
access point. And so if we get that coming from a number of different access
points,
then we can figure out exactly where this device is. Now this relies on a very
finely synced set of times on the access points. They have to know exactly what WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
finely synced set of times on the access points. They have to know exactly what
time it is. They have to be highly synchronized. So they can tell exactly when
this
signal arrived relative to when it was probably transmitted. And yeah, that is
going to require us to be so highly synced that we're talking about microse
conds
at this point, which hey our network is capable of doing. We just have to make
sure we have it. Angle of arrival is going to compare how the signal arrives on WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
sure we have it. Angle of arrival is going to compare how the signal arrives on
one access point or one antenna compared to another antenna and try to say okay
well based on this angle, it's probably this direction, which is another way
that
we can remove signal strength from the equation. So either way, these are our
techniques and we aren't necessarily usually going to drill into the specifics
of
that within our designs and even our implementations, but it does help us to
understand a little bit more of how we need to change our wireless designs when WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
understand a little bit more of how we need to change our wireless designs when
we have location as a requirement. So what are we going to do here? Well, again
, we
have some design changes that are going to be required. And here's the biggest
one of them all. We need to deploy access points to the perimeter of a building
.
What do we mean by this? Well, typically a wireless design that's a little bit
more focused on again coverage and it could even be capacity and coverage. But WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
more focused on again coverage and it could even be capacity and coverage. But
what do we do? We deploy the access points throughout the space like this and
we
find that hey this is great. We can cover the entire space. We can have good
overlap and we're able to cover everything that we need except there's a
problem with this from a location perspective, which is what if the device is
here on the wall? What do we say about triangulation and just in general all of WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
here on the wall? What do we say about triangulation and just in general all of
these other techniques? We need multiple access points to be involved with
tracking down where it is. Now I do have two access points here that can
probably
see the device, but what we really need is for this to be in the middle of the
access points. You know, we can form a triangle over here for example and we
can
leverage the high accuracy techniques as best we can, but the further away a
device is the less accurate it's going to be. So instead of deploying our WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
device is the less accurate it's going to be. So instead of deploying our
wireless design like this, it is going to require a change where we place
access points around the perimeter of the building. Something we've never had
to
do in the past because it's considered a waste. I mean my cell is going to look
like this and look at all of the signal that's bleeding out into the parking
lot.
We would never want to do this if location isn't on the table because again it
's
sort of a waste of wireless signal. And yet with location this is going to be WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
sort of a waste of wireless signal. And yet with location this is going to be
required because now when I have a wireless device that's over here, well at
least we've got a lot better chance of seeing where that device is. If it's
over
here, for example, we've got a triangle that can see it and so you know maybe
we
want to put this in the corner a little bit more and get a triangle that way,
but
we start to see where our access points need to go relative to a design that WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
we start to see where our access points need to go relative to a design that
doesn't include location services. Now when it comes to deploying location
services within the Cisco space, we should be aware that we're going to need
the
proper solutions in place. Now fortunately all of Cisco's access points in
wireless LAN controllers are equipped to give us location services from a
high accuracy perspective. They're capable of deploying all of these different
methods, but we will need some software to aggregate all of this information WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
methods, but we will need some software to aggregate all of this information
and
this takes the form of Cisco software that today is known as Cisco Spaces. I
say today because it used to be known as DNA spaces and so the name has changed
and Cisco likes to rebrand things and so be aware of that. Now you might find
some
documentation that refers to Cisco's mobility services engine, their connected
mobile experiences, prime infrastructure. A lot of these are more legacy
products
that used to be required for location services. These have been retired or WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
that used to be required for location services. These have been retired or
otherwise on their way out the door and so instead we're going to see that we
need to connect into this software package called Cisco Spaces which gives us
the floor plans which can show us where devices potentially give us some
historical tracking and when we're building out our wireless designs we would
want to make sure that we're asking the question about licensing costs,
whatever
it takes to deploy this particular software package to go with the design, the WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
it takes to deploy this particular software package to go with the design, the
access point design that we're creating that places them around the perimeter.