Technical Difficulty Rating: 6 out of 10
Deciding what type of wireless technology your new product should use can be an overwhelming task. Not only are there a huge number of wireless technologies currently available, but it’s also a moving target with new technologies regularly being introduced.
To help simplify the process of selecting the best wireless tech for your product I’ve organized the various wireless technologies into a groups based on functionality, data speed, and operating range.
Based on the intended functionality of your product, it should be relatively simple for you to immediately determine which group of technologies you need to consider.
For example, if you require two devices separated by 30 feet to transfer low amounts of data then it doesn’t make sense to use any of the long-distance or high-speed wireless technologies.
That being said, I recommend that you read this entire article regardless of your product’s specific needs because you can gain a general understanding of all the wireless technologies available to you.
Peer-to peer simply means when two devices are connected together for direct communication. Only two devices can normally participate in a peer-to-peer connection.
In the next section I’ll discuss what are called mesh network technologies which allow many devices to all be interconnected.
The best known peer-to-peer wireless technology is Bluetooth. When you connect your phone to a Bluetooth speaker that is a peer-to-peer wireless connection between your phone and the speaker.
Bluetooth dominates peer-to-peer streaming audio applications such as this Bluetooth headset.
Because of the relatively short operating range, Bluetooth is fairly low power. It consumes much less power than WiFi, and a lot less than cellular technologies, but still significantly more than technologies such as Bluetooth Low-Energy or Zigbee.
Everyone knows about WiFi, but few people have heard of WiFi Direct. This is true even though nearly all phones and tablets support it. Like Bluetooth, but unlike traditional WiFi, WiFi Direct is a peer-to-peer wireless technology.
As you probably already know, traditional WiFi sets up an access point that allows many devices to connect to it. But what if you want to transfer data directly from one device to another without the overhead of an access point? That is where WiFi Direct comes into play.
WiFi Direct uses the same basic technology as traditional WiFi. It uses the same frequency and offers similar bandwidth and speed. But, it doesn’t require an access point, allowing two devices to have a direct connection similar to Bluetooth.
The advantage of WiFi Direct over Bluetooth is mainly faster transfer speeds. In fact, WiFi Direct is over a hundred times faster than Bluetooth. That speed comes at a price though and that price is mainly higher power consumption.
Near field communication (NFC) is fundamentally different than the other wireless technologies discussed in this article. NFC communicates using electromagnetic fields shared between two coils, whereas all other wireless technologies emit radio waves.
Because NFC communicates via two coils that are electromagnetically coupled together, the operating range is only about an inch or two. The two coupled coils essentially form a transformer with an air core.
The most common use for NFC is in contactless payment systems. Although payment data is of course encrypted, the extremely short operating range of NFC also helps to eliminate the possibility of someone else nearby hacking the transaction.
NFC allows the use of passive NFC tags. In this case passive means there is no power source. Instead, a passive tag is powered from the electromagnetic field of an NFC reader device. Both communication and power transfer are occurring between the two coupled coils.
The advantage of passive tags is they are simple, cheap, small, and last almost indefinitely since there is no battery. Active tags are also available which include a battery.
As a side note, wireless charging, where you recharge a device by placing it on a charging mat, also takes advantage of this same phenomenon of power transfer between two coupled coils.
Low-power / Short-range / Low-data Mesh Technologies
There are four common technologies for creating a low-power, low-data network: Bluetooth Low-Energy, Zigbee, Z-Wave, and 6LoWPAN.
If your product is battery operated, and needs to send relatively low amounts of data a short distance away, then one of these four technologies is likely the best solution.
A critical feature supported by all four of these technologies is called a mesh network, sometimes referred to as a many-to-many network.
A mesh network allows many-to-many communication.
Normally, to send data from device A to device C you must form a direct link between device A and device C. This is the case for peer-to-peer technologies such as Bluetooth and WiFi Direct.
But with mesh networking you can instead send data from device A to device C via device B. The data is sent from device A to device B, which then relays the data to device C. This allows you to create a huge network of interconnected devices that can cover a large area with extremely low amounts of power.
For example, imagine that you have 26 devices labeled A through Z, which are spaced out in a line with one hundred feet between each device. Normally, if you wanted to send data from device A all the way to device Z located 2,500 feet away, you would need a transmitter with considerable power. This requires a product with a large battery.
But with mesh networking, you can relay the data from device A to device B, to device C, and so on all the way to device Z. No single device has to transmit the data more than a hundred feet, so the power required by each device is much smaller.
Mesh networking can open up a lot of really interesting applications.
Bluetooth Low-Energy (BLE)
Bluetooth Low-Energy is much more than just a low-energy version of Bluetooth Classic. In fact, it’s applications are completely different than for normal Bluetooth.
Bluetooth LE is probably the most common type of wireless functionality for the products I help develop. It is designed to transmit/receive small amounts of data on a fairly infrequent basis, all while consuming extremely low amounts of power.
BLE has many applications but one of the most common is transmitting sensor data. A sensor device that measures the temperature once per minute, or a GPS device that records and transmits its location every 10 minutes, are a few examples.
In many cases, Bluetooth LE products are powered only from a small coin cell battery. If data is only sent infrequently, a BLE device running from a coin cell battery may have a battery life of a year or longer.
Bluetooth LE is widely supported by mobile phones and tablets making it an ideal solution for interfacing your product to a mobile app. It also supports a decent transfer speed of up to 1Mbps (classic Bluetooth can do up to 2-3 Mbps).
As with all of the technologies discussed in this section, BLE supports mesh networking. In fact, it allows mesh networks with up to 32,767 devices!
Unless you have a solid reason for choosing one of the other technologies I discuss in this section (Zigbee, Z-Wave, and 6LoWPAN), I highly suggest that you use Bluetooth LE. It’s the easiest wireless technology to implement, consumes very little power, and is the most widely supported.
BLE, Zigbee, Z-Wave, and 6LoWPAN are all potential solutions for smart home applications.
Zigbee is another short-range, networking technology similar in many ways to Bluetooth LE with similar applications. It uses the same 2.4 GHz carrier frequency, consumes very little power, operates over a similar range, and offers mesh networking.
In fact, a Zigbee mesh network can include up to 65,000 devices which is twice as many as Bluetooth LE can support. However, I have yet to see an application that pushes either limit.
Zigbee is primarily used for home automation applications such as smart lighting, smart thermostats, and home energy monitoring. It is also commonly used in industrial automation, smart meters, and security systems.
Z-Wave is a proprietary wireless technology (acquired by Silicon Labs in 2018) that primarily competes with Zigbee and BLE in the home automation market.
Unlike BLE and Zigbee, which use the popular 2.4 GHz band, Z-Wave instead uses a sub-1GHz band. The exact band varies across many countries which can cause complications if you wish to sell your product globally. In the U.S., Z-Wave operates at 908 MHz, whereas in Europe it uses 868 MHz. Other countries and regions use everything from 865 MHz to 921 MHz.
There are two significant advantages of the lower carrier frequency: increased range and reduced interference. Lower frequency radio waves propagate further. The 2.4 GHz band used by BLE and Zigbee is also used for WiFi, Bluetooth Classic, and even your microwave oven, so there is a lot of potential for interference.
The frequency bands used by Z-Wave tend to be much less crowded. The downside of the lower carrier frequency is a lower data transmission speed which ends up being almost 10 times slower than Bluetooth LE.
Z-Wave supports smaller mesh networks up to 232 devices, which is more than sufficient for most applications.
6LoWPAN is a strangely named technology that combines two different acronyms. The 6 refers to Internet Protocol (IP) version 6 and the LoWPAN refers to Low-power Wireless Personal Area Network. Catchy name, I know.
6LoWPAN is essentially a new competitor for Zigbee. The primary differentiator is that 6LoWPAN is an IP-based network like WiFi. As with Zigbee and Z-Wave, 6LoWPAN is primarily used for home automation applications and smart meters.
Local Area Network (LAN) Technologies
WiFi, perhaps even more so than Bluetooth, likely requires little introduction. If your product requires access to the internet, and will always be used near a WiFi access point, then WiFi is the answer. WiFi is known as a Local Area Network (LAN) technology due to its moderate coverage area.
WiFi is fast, cheap, easy to implement, has a good operating range, and is widely available. The biggest downside of WiFi, at least for mobile products, is the power consumption. Because of the higher power consumption, you are usually better off using other wireless technologies if you don’t really need the performance offered by WiFi.
Long-distance Cellular Technologies
If your product needs access to the cloud, yet it won’t be consistently located near a WiFi access point, then your product will likely need a cellular radio for long distance communication.
The exact type of cellular technology required for your product depends on how fast you need to transfer data, and to a lesser extent on where your product will be sold.
GSM / GPRS
For a long time GSM (Global System for Mobile communication) coupled with GPRS (General Packet Radio Service) for data transfer has been the most commonly used cellular technology for products that don’t require large amounts of data transfer. This is mainly due to the wide availability and the relatively low hardware cost of GSM/GPRS hardware.
Unfortunately, that is coming to an end. Most of the cellular carriers around the world are phasing out GSM so they can free up more bandwidth for 4G and 5G smart phones which require huge amounts of data transfer.
Even more unfortunate, there is no obvious alternative technology, at least yet. The most likely option is to upgrade the hardware from a GSM solution to an LTE cellular technology, but that comes with a large price increase.
LTE is a 4G cellular technology that supports much faster data speeds than GSM. If your product requires very fast cellular data transmission speeds, then LTE is likely the best choice.
But if your product doesn’t really require that level of data speed, then you will be paying for hardware you simply don’t need. An embedded GSM module can be purchased from China for only a few dollars, whereas LTE modules can cost more than $20. The carrier service cost for LTE will also be significantly higher than for GSM.
With the huge popularity of Internet-of-Things (IoT) devices, this gap in technology choices has become even more pronounced. This gap is in the process of being filled, though, by several different new wireless technologies which I’ll discuss in the next section.
Low-power Long-distance Technologies
If you require long-distance, low-data communication, as do many IoT products, then your technology choices aren’t as clear as for other applications. This type of network is commonly referred to as a LPWAN or Low-Power Wide Area Network.
For example, if your product collects weather data at remote locations and automatically uploads that data to the cloud, then a LPWAN technology is likely needed. As I’ve already pointed out, neither GSM or LTE cellular technologies are good fits for low-data rate applications.
There are other wireless technologies available that offer good solutions to this problem, including LoRa, NB-IOT, and LTE-M. Unfortunately, none of these are widely supported global standards. This makes their implementation challenging, or impossible, for many products depending on where they will be sold.
LoRa / LoRaWAN
LoRa (short for Long-Range) enables very long-range communication of more than 6 miles in some areas, while consuming little power. It is a proprietary wireless technology acquired by Semtech in 2012.
LoRa uses various frequency bands depending on the region of operation. In North America 915 MHz is used, and in Europe the frequency is 868 MHz. Other areas may also use 169 MHz and 433 MHz as well.
LoRa refers to the underlying technology and can be directly used for peer-to-peer communications. LoRaWAN refers to the upper layer networking protocol.
If you are looking for a low-power, long-distance, peer-to-peer solution, then LoRa is a great choice. You can typically purchase LoRa modules cheaper than LoRaWAN modules.
If you wish for your product to connect to an existing LoRaWAN network, then a more expensive LoRaWAN module is required with the network layer included. Unfortunately, LoRaWAN networks are only available in parts of Europe and not in North America. This severely limits the usefulness of LoRaWAN for most products.
Although LoRa is designed to operate over a huge range, it is not a cellular technology that can connect to mobile networks. This makes it less complex, and cheaper to implement, but it’s applications are limited.
For example, if your product requires long-distance access to the cloud then you would need to also supply a LoRa gateway device for connecting to the internet. The gateway device connects to the internet, and communicates with any remote LoRa devices.
LoRa does not provide any single remote device a method to remotely access the cloud, assuming there is no LoRa gateway within the operating range.
Unlike LoRa/LoRaWAN, NB-IOT is a cellular technology. This means it is more complex, more expensive to implement, and consumes more power. But, it offers higher quality cellular connections and direct access to the internet.
NB-IOT is only intended for transmitting very small amounts of data. The biggest downside of NB-IOT is the limited availability. No U.S. carriers support it yet, and it is currently only being tested in Europe. But it is expected to become available in the U.S. sometime in 2019.
This technology doesn’t likely make sense to implement in your product now, but it will become more practical within the next couple of years.
If your product requires long-distance cellular access with higher data rates than supported by either LoRa or NB-IOT, then LTE-M may be your best choice.
LTE-M is an abbreviation for LTE (Long Term Evolution) Cat-M1. This technology is for Internet of Things devices that need to connect directly to a 4G mobile network. It is a subset of the LTE cellular technology that is optimized for low data rate devices running from small batteries.
LTE-M differs from standard LTE in a few critical ways. First, it is cheaper to implement because simpler chips can be used due to the more limited bandwidth.
Secondly, it’s optimized for reduced power consumption so as not to quickly drain small batteries. Finally, the cellular service costs are significantly lower because you aren’t using anywhere near the bandwidth required by standard LTE.
The key to selecting a wireless technology is to narrow down your requirements so you can focus exclusively on the viable technologies. The required operating range, the data transmission speed, the power consumption, and the cost are the primary criteria for selecting a wireless technology.
Of course, as with all things in engineering, you can’t have everything your way. For example, a large operating range requires increased power consumption. The same is true for faster data rates. There will always be some give and take between these criteria. There is never a perfect solution.
If you are looking for a technology that offers long-distance, low-power, high data speeds, and low cost, you will never find a realistic solution. Instead, I suggest you prioritize your design criteria and begin narrowing your choices from there.
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