Wireless networking consists of many different network technologies in various combinations. In this video, you’ll learn about wireless frequencies, Bluetooth, RFID, and other wireless technologies.
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When we talk about 802.11 technologies, we often talk about frequency use. And there are two major bands that we use for these frequencies. One of these bands is the 2.4 gigahertz range, and the other is the 5 gigahertz range. And there are some 802.11 standards, like 802.11n, that can use both of these ranges at the same time.
You may notice, in your configuration of 802.11 wireless access points, that you’re able to choose a channel of frequencies to use. This is a grouping of frequencies the IEEE has put together and has assigned numbers to it. For example, if you were choosing a 20 megahertz block of frequencies in the 2.4 gigahertz range that centered around 2412 megahertz, the IEEE calls that channel 1.
Some of these channels overlap with each other. So you may find in the 2.4 gigahertz range, that channel 1 and channel 2 slightly overlap. And we often say that we would like to use channel 1, channel 6, or channel 11 because we know those 20 megahertz bandwidths will not overlap with each other if you choose those channels.
Some wireless standards will use a 20 megahertz block of frequencies to be able to communicate. Others will expand that bandwidth into 40, 80, and 160 megahertz blocks. The modulation used for these 802.11 standards tends to dictate how much bandwidth will be used. For example, 802.11a, 802.11b, and 802.11g used about a 20 megahertz channel bandwidth.
With 802.11n, you have the choice between a 20 megahertz bandwidth, or you could double that to use a 40 megahertz bandwidth which was two contiguous 20 megahertz bonded channels. There’s limited bandwidth available at 2.4 gigahertz, so by bonding together and creating a 40 megahertz channel, using most of the available bandwidth.
With 802.11ac, you’re running in the 5 gigahertz frequency range which gives you much more bandwidth available. If you’re running 802.11n stations on this 802.11ac network, then you can use the 40 megahertz bandwidths that were available with 802.11n. If you’re using 802.11ac networking, then you’re using 80 megahertz bandwidths by default, and you have the option to use 160 megahertz bandwidths.
Lets visually see what this looks like for the 2.4 gigahertz range and the 5 gigahertz range. All of the colors that we see here that our blue, gold, and green are channels that are available to use in these frequencies. If you see the red color, that means that those frequencies are not available for 802.11 networking.
You can see for 2.4 gigahertz, we have three 20 megahertz blocks available– channels 1, channel 6, and channel 11, and that’s the only spectrum available in the 2.4 gigahertz range. Now, let’s look at how much bandwidth is available at the 5 gigahertz range, and you can see it’s a significant difference than running at 2.4 gigahertz. Remember that anything that’s colored red is unavailable, but all of the other colors are available as 20 megahertz channels in the 802.11 5 gigahertz range.
We mentioned earlier that 802.11n could use 40 megahertz ranges, and you can see those ranges are broken out. And, of course, anything that’s red is unavailable. If you’re using, 802.11ac then you’d be using 80 megahertz ranges. You can see there are 1, 2, 3, 4, 5, 6 of those ranges available. And if you’re using the optional 160 megahertz range with 802.11ac, you have two contiguous ranges that you can use in the 5 gigahertz band.
Another common networking technology we use wirelessly over a short distance is Bluetooth. This is called a Personal Area Network or a PAN, and we commonly see Bluetooth use to connect many different kinds of devices– our smartphones and tablets, our automobiles, our health monitors and smartwatches, and we also use Bluetooth for tethering and file transfers between our devices.
A popular wireless technology that we find in access badges, in our animal identification technologies, or really anything that we might need to be tracked is RFID. That stands for Radio Frequency Identification. These are very small tags that we can put in anything that we’d like to track. Here’s a size comparison of an RFID tag and a grain of rice. You can see they’re very small, so you can put them almost anywhere.
Here’s another RFID tag. This one is flat so it makes it very easy to put into things like cards that we would use for access. These RFID tags work using radar technology. This RF energy is set out, captured by the tag, and is used to power the RFID tag. The tag then sends out an ID signal which then can be captured. You might also find RFID tags that are already powered. Those are active RFID tags
An advanced form of RFID is one that we put into many of our mobile phones. This is Near Field Communication or NFC. This allows us to use our phones as identification devices so we’re able to pay for systems with a credit card or an online wallet. We can use NFC to help with the pairing process with Bluetooth, or it can act as an identity card to prove that you are who you say you are or give you access to a locked room.
There are two major wireless standards associated with Internet of Things technologies, and one that is an open standard is Zigbee. This is an open standard called the IEEE 802.15.4 Personal Area Network. Instead of using Wi-Fi or Bluetooth, you can use a Zigbee-connected device. It uses less energy and less power than Wi-Fi and can go longer distances than a Bluetooth connection.
Unlike 802.11, which has a central access point, and all devices have to be able to communicate to that access point, Zigbee is a meshed network. This means that your Zigbee network can be quite large because all of the Zigbee devices can communicate through each other to expand the size of the network. Zigbee communicates over the ISM ban. That’s the Industrial, Scientific and Medical band, and it communicates over 900 megahertz and 2.4 gigahertz frequencies in the United States.
The other competing technology for this wireless Internet of Things meshed network is Z-Wave. This is a proprietary networking type, but it is also commonly used as the Internet of Things networks for your lights, your garage door, and other home automation. Similar to Zigbee, Z-Wave is a meshed network which means that nodes can hop through other nodes on their way to the destination. This is also using the ISM band, and it’s using the 900 megahertz frequencies of the ISM band in the United States.
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