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WiFi vs. Bluetooth: Wireless Electronics Basics

Sam Sattel

eagle-academy

Wireless Electronic Basics: What is the Difference Between WiFi and Bluetooth?

Planning to start your first electronics design project? Chances are you’ll be including some kind of wireless functionality to communicate with the web or other devices. While there are many ways to communicate wirelessly, the two kings of the wireless world deserve some attention in your list – WiFi and Bluetooth. But how exactly do these two technologies work that we rely on so heavily today, and how do you know which one to use in your first project? Let’s find out.

Sharing a Common Foundation

Before we even dive into the differences between WiFi and Bluetooth, it’s important to note that both of these technologies share a common foundation in the wireless electronics family through their use of radio waves. As we’ve covered in our past blogs in the Wireless Electronic Basics Series, radio waves are but one of many waves in the electromagnetic spectrum, which includes other family members like x-rays, gamma rays, infrared rays, and more. These waves can all defy even the toughest physical barriers, transmitting data, video, audio and more through the vacuum of space at the speed of light.

electromagnetic-spectrum

Here’s a great visual for how the electromagnetic spectrum is organized, starting with low frequency and low wavelength on the left. (Image source)

On this electromagnetic spectrum, you can measure and classify radio waves that are used in Wifi, Bluetooth, and other applications in one of two ways:

  • By Frequency. This is the count of how many electromagnetic waves pass through a given point every second, and is measured in Hertz.
  • By Wavelength. This is the distance that you can measure between two of the highest points in a radio wave, which can range anywhere from 100 meters to 1 centimeter depending on the radio wave you’re observing.

Within the radio wave family, there are distinct bands separated by both frequency and wavelength which provides some specific channels that devices can be used on. Check out the table below to see how these break down:

Name Abbreviation Frequency Wavelength
Extremely low frequency ELF 3–30 Hz 105–104 km
Super low frequency SLEF 30–300 Hz 104–103 km
Ultra low frequency ULF 300–3000 Hz 103–100 km
Very low frequency VLF 3–30 kHz 100–10 km
Low frequency LF 30–300 kHz 10–1 km
Medium frequency MF 300 kHz – 3 MHz 1 km – 100 m
High frequency HAF 3–30 MHz 100–10 m
Very high frequency VHF 30–300 MHz 10–1 m
Ultra high frequency UHF 300 MHz – 3 GHz 1 m – 10 cm
Super high frequency SHF 3–30 GHz 10–1 cm
Extremely high frequency EHF 30–300 GHz 1 cm – 1 mm
Tremendously high frequency THF 300 GHz – 3 THz 1 mm – 0.1 mm

Both WiFi and Bluetooth share their space in the Ultra high frequency (UHF) band between 300 MHz and 3GHz, along with other gadgets like baby monitors, cell phones, and more. You’ll also find WiFi advancing into the Super high frequency (SHF) band between 3GHz and 30GHz in its most recent evolution.

It’s because of these separate bands that you can listen to things like your morning AM radio talk show while at the same time browsing the web on your smartphone. Connecting through WiFi on your phone uses the UHF band, whereas AM radio uses the lower frequency bands between 535 kilohertz and 1.7 megahertz.

The World Wide Web of Wifi

wifi-logo

WiFi is the most popular method to allow devices to communicate across both a local wireless network and also connect to the internet. Much like other two-way radio devices, WiFi shares some common similarities. Picture this:

Inside your laptop, you’ve got a wireless adapter which can function as both a transmitter and receiver of information in the form of radio waves. To both send and receive information your adapter gets some help from an antenna. On the other side of your home, you likely have a wireless router which has another transmitter and receiver that can also share data wirelessly, along with a physical connection to the internet via Ethernet.

Connecting both your laptop and router together on the same radio frequency band is what allows them to both communicate with each other and send data back and forth in the form of videos, audio, websites, and more.

2.4GHz and 5GHz

On the radio frequency table that we showed above, WiFi works on two separate bands at both 2.4GHz (the UHF band) and 5GHz (the SHF band). Simple enough, right? If you need a way to connect a device to the web to communicate with services all around the world, then something like an embedded wifi module on a microcontroller or even a wireless adapter that can play into a USB or PCI port will be your best bet. But before you go running off to purchase the wireless adapter you need, you’ll need to know about the WiFI networking standards.

new-adafruit-wifi-microcontroller-breakout

An Adafruit microcontroller board with WiFi built in. (Image source)

Fun Fact: WiFi doesn’t actually stand for anything like some people think it does. It was a name created by a brand consulting firm back in 1999 when they needed a sexier name for IEEE 802.11b Direct Sequence. Definitely a bit more catchy!

The Evolution of WiFi Networking Standards

WiFi has steadily evolved over the years to handle our growing needs for faster data transfer rates. It has also had to expand to deal with the increasing number of devices that are being used on our WiFi networks across the world including video game consoles, smartphones, digital cameras, tablets, printers, and a whole lot more. Regardless of the device, all WiFi uses the same 802.11 networking standard, which will come in a variety of flavors, including:

802.11a

This WiFi standard uses the 5GHz frequency band on the radio wave spectrum and is capable of moving data at up to 54 megabits per second (Mbps). It also uses a fancy technology called orthogonal frequency-division multiplexing (OFDM), which splits a radio signal into several sub-signals to reduce potential signal interferences.

802.11b

This has been the most popular WiFi networking standard until recently but also happens to be the slowest. You’ll find 802.11b hanging out on the 2.4GHz frequency band, and it can only send and receive data at 11 Mbps.

802.11g

This WiFi networking standard is similar to 802.11b in that it does its work on the 2.4GHz frequency band. It’s also a lot faster, capable of sending data at up to 54 Mbps thanks to OFDM technology inherited from 802.11a.

802.11n

This is the most widely used of the WiFi networking standards out there, and for a good reason – it’s fully backward compatible with 802.11 a, b, and g. This standard can also transmit up to four streams of data at the same time, all at 150 Mbps, which makes it perfect for our multi-device wireless households.

802.11ac

This is the newest standard to join the WiFi family and is still in the process of being reviewed by the Institute of Electrical and Electronics Engineers (IEEE). Like 802.11n, this standard is fully backward compatible with all the other networking standards, and works on both the 2.4GHz and 5GHz band, slamming data around at 450 Mbps!

WiFi and Interference

Like any other radio wave signal, WiFi is susceptible to interface from other devices that are using the same frequency band. This can include things like microwave ovens, cordless telephones, and other Bluetooth devices which rely on 802.11 b and g networking standards. Because of this potential for interference, WiFi signals come with different channels allowing these devices to jump at will. There’s 11 channels in the United States standards, 14 in Japan, and 13 in Europe.

When working with WiFi in your electronics project, you might need to adjust the channel you’re connecting to if your connection keeps dropping or slowing down. It just might be that everyone else in your neighborhood is hanging out in the same channel and clogging things up. There are some cool apps out there that let you see all of the WiFi signals in your neighborhood in real-time, like this WiFi Analyzer for Android.

Keeping It Low Key with Bluetooth

Unlike WiFi, which connects devices to the Internet and shares big chunks of data back and forth, Bluetooth is more concerned with small-area networks and connecting individual devices together without requiring an internet connection. However, like WiFi, Bluetooth also operates on the same radio frequency band at 2.45GHz, but the potential for interference is a lot lower. Why’s that? Two reasons:

  • Weaker Signals. Bluetooth devices send out a much weaker signal than other wireless devices, measuring in at only 1 milliwatt. And while this does limit the range that a Bluetooth network can reach, it helps to create a small, isolated bubble of devices that don’t interfere with other wireless devices.
  • Hopping Signals. Bluetooth also uses a nifty technology called spread-spectrum frequency hopping that allows it to jump around between 79 unique frequency channels up to 1,600 times per second! So even if two Bluetooth networks did happen to be hanging out in the same channel, it hardly matters since they’ll switch channels the next second.  

How are Bluetooth devices able to connect though? You’re probably used to the traditional pair, pin and connect process, but let’s see what’s going on behind the scenes. Say you just got yourself a brand new car with some built-in Bluetooth and you want to stream music from Spotify. Both your car and your phone have a Bluetooth transmitter inside, both of which come with their unique Bluetooth address.

When you start to connect your vehicle’s Bluetooth to your smartphone, the car’s transmitter will send out a radio signal broadcasting its unique address and looking for other transmitters with an address in the same range. Once it discovers the Bluetooth address on your smartphone, you’ll enter a few digits as the standard security process in Bluetooth, and the two devices will connect.

paring-car-phone

Most newer cars ships with built-in Bluetooth, hello wireless streaming! (Image source)

Once connected, this will create what’s called a personal-area network (PAN), also referred to as a piconet. What you’ve created here between your car and smartphone is a little mini network made just for your device. The Bluetooth transmitter in your car and smartphone can then jump around from frequency to frequency to avoid interfering with any other piconet cars cruising around the streets.

WiFi and Bluetooth, Side-by-Side

As you can see, both WiFi and Bluetooth have some very specific domains that they both serve in the realm of wireless communications. You’ll want to use WiFi in your electronics project if you need to connect your gadget to the internet. But if you just need to connect devices together without needing an internet connection, then Bluetooth is your tool of choice. Let’s take a final look at some side-by-side comparisons on the technical limitations of both technologies:

Versions

Bluetooth has gone through several upgrades, from Bluetooth 2.0 to the latest Bluetooth 4.0. All of the evolutions come with enhanced data rates and low energy protocols. WiFi has also seen a steady stream of updates, from 802.11b to the most recent 802.11ac which provides dual 2.4GHz and 5GHz frequencies, higher data transfer rates, and better security protocols.

Frequency

Bluetooth only does its work on a 2.4GHz frequency, whereas many WiFI networks these days will run on both 2.4GHz and 5GHz frequencies. You’ll find many of today’s newest wireless devices taking advantage of WiFi’s 5GHz frequency, which isn’t nearly as congested as the 2.4GHz frequency and helps to reduce any potential interference between WiFi and Bluetooth networks.

Data Transfer

Bluetooth 4.0 can only transfer data up to 25 Mbps, whereas the latest version of WiFi can transfer data at up to 250 Mbps. While it’s a big leap between the two, remember that Bluetooth devices aren’t going to be downloading huge files, and their weaker data transfer speeds are still perfect for audio communications.

Range

Here’s an important one that might affect your project. The range on a Bluetooth network gets cut off at about 30 meters, whereas the latest versions of WiFi can reach out beyond 100 meters. This is going to be important to keep in mind if you’re designing something like a drone, which will probably need that added range to keep on flying.

Power

Because of its greater range and added layers of security protocols, WiFi uses way more power than Bluetooth. If you need a lower power device, then be sure to go with Bluetooth which only uses about 3 milliamps of current.

Connections

With Bluetooth, you can connect up to 7 devices together in one personal area network (PAN). WiFi doesn’t have the same limitations, but how many devices a WiFi network can handle will be largely determined by the bandwidth of the router you are connected to.

Ride the Wave

There you have it, all of the finely combed details about the two most popular wireless technologies ruling the world – WiFi and Bluetooth. Knowing which to choose for your first electronics project comes down to several questions you’ll need to ask yourself. Do you need your device to connect to the internet? Then WiFi will be the way to go. Or maybe you just need to connect two devices together, like between your car and smartphone? Bluetooth all the way. One thing to keep in mind is that neither of these technologies is necessarily better than the other. They both fill very specific niches in the amazing and mysterious world of wireless electronics and will continue to evolve and advance as time goes on. And it’s not like you have to choose either, maybe you need both!

Did you know that Autodesk EAGLE includes a ton of free microcontroller libraries with Bluetooth and WiFi already built-in? Try Autodesk EAGLE for free today to check them out.

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