IoT connectivity
This blog post is an addition to the YouTube video above.
I'm describing different connectivity types that you can use for your Internet of Things project and present their pros and cons.
Wi-Fi
Wi-Fi is the most used and the most popular wireless connectivity in the world.
It's been around for over 20 years now, and is backward compatible so it's still possible to use old installations (however speeds achieved on such installation would be very slow as first version could achieve up to 2Mbit/s)
As it's easy to run your own, well encrypted (using WPA2) Wi-Fi network on a device that costs no more than $20, it's often the first and the best choice for DIY built connected devices. There's also a plenty of affordable ($5 or even $1) chipsets, powerful enough to run more than basic operations, that can use Wi-Fi as networking.
The upsides of Wi-Fi:
- easy to run
- availability of microcontrollers
- cost
And the downsides:
- energy consuming
- fair to middling range
- Wi-Fi networks are densely packed, which can affect connectivity
Cellular
Another widely available and popular connectivity type is cellular - be it GSM, LTE or 5G.
Most of developed countries in the world have good coverage of at least one of aforementioned networks. While cellular networks are great for connecting devices installed in remote places, there's an issue of interoperability of such devices i.e. GSM modem won't work with LTE network and vice versa. Another issue is relatively high power consumption of cellular modems. This is where new generation of cellular technologies emerges - NB-IoT and LTE-M.
LTE-M has maximum rates of 375kbps for downlink and 300kbps for uplink. Since it uses narrower bandwith compared to regular LTE, it has longer range than NB-IoT.
NB-IoT is a narrowband technology that uses physical layer around LTE bands.
It has a maximum downlink at 60kbps and 30kbps for uplink, but is really energy efficient so if you don't need high speed but are focused on energy usage, go for it (if you can).
There's also 5G technology that's gaining popularity.
It comes in a few variants: low-band, long range version; mid-band, medium speed and range; and mmWave, very high speed version (up to 10Gbps). It is still available only in pilot installations in different parts of the world and has very limited hardware support.
The issue with these is they're not widely adopted yet and you need to rely on big telcos to install base stations for both technologies.
Upsides:
- widely available
- many modems for GSM and LTE
- quite cheap data usage
- high speeds when using LTE or 5G
- very good range
- new generations are energy efficient
Downsides:
- lack of interoperability
- still low adoption of NB-IoT and LTE-M
- may require dedicated M2M plan
- dependency on third-party companies
- high power usage for traditional networks like GSM or LTE
- few chipsets supporting newer networks
LoRa (and LoRaWAN)
While LoRa can be described as three different things (radio modulation scheme, systems and communication network) I will mix them here.
First, an explanation: LoRa and LoRaWAN is not the same thing. LoRaWAN is MAC-layer protocol running on LoRa modulation.
LoRa’s modulation format is best described as a “frequency modulated (FM) chirp.”
LoRa uses 3 different ISM radio frequency bands - 868MHz (Europe), 915MHz (US), and 433MHz - with high link budgets (up to 170dB) that together give us more than 10 km range in rural areas. It also offers geolocation and, when using LoRaWAN, encryption by default.
Typical LoRaWAN stack consists of an end device (think of sensor), a gateway, a network server and an application server.
The end device sends the data to the gateway, which then sends it to the network server that, in turn, sends the data to the application server.
Upsides:
- extremely long range (world record of 766 km)
- low energy consumption (a sensor can run up to 10 years on a single battery)
- works well in cities thanks to using ISM bands
- LoRa Alliance keeps an eye on standardization
- possibility to build your own private network
Downsides:
- very low data transfers
- no message receipt when using LoRaWAN
- hardware is not the cheapest
- lost of development work required
Z-Wave
Z-Wave is a wireless protocol used mainly in home automation. It is a mesh network (meaning nearby devices can talk to each other and forward the signal) using low-energy radio waves. There is a wide range of interoperable devices using Z-Wave as a connectivity (over 2600 different devices in 2019 - keyfobs, thermostats, windows, locks, etc.).
It uses different frequencies in different parts of the world.
With it's decent range (90 meters outside, around 30 meters inside), it's a good choice for smart home installations.
Upsides:
- many devices available on the market
- decent range
- mesh networking
- works within ISM frequencies at around 900MHz
- specifications released into the public domain in 2016
Downsides:
- range suitable only for home automation and similar uses
- low data transfers
- battery powered devices cannot be part of a mesh network
ZigBee
ZigBee is 802.15.4 based specification for high-level communication protocols. It's used to create small, low power networks for home automation, medical device data collection or some other small scale wireless projects. It offers a range between 10-100 m line-of-sight. It has built-in encryption and a maximum rate of 250kbit/s.
Typical usage includes home automation, building automation, industrial control systems or wireless sensor networks. It supports star and mesh topologies.
Upsides:
- easy to set up
- no central point of network
- low power usage
- decent range
- exists since 1998
Downsides:
- bit outdated security (128bits symmetrical keys)
- limited coverage, need to build own infrastructure
- exposed to attack by unauthorized people (as every wireless network)
- low data rate
Bluetooth (Low Energy)
Bluetooth is being used in wireless connectivity for a long time.
Most of people probably think of headsets and mobile phone accessories when hearing about it.
There is, however, a variation of it called Bluetooth Low Energy (BLE) invented in 2001 at Nokia.
The data rate for the first version of BLE has been set to 1Mbps, which makes it faster than the competition like Z-Wave or ZigBee. The second iteration (with Bluetooth 5.0) offers a data rate of 2Mbps, which is quite fast for IoT applications like sensors or medical devices. It also extends the range 4 times (up to 800m line-of-sight).
Upsides:
- very popular
- low power consumption
- wide range of applications
- reasonable range
- good data transfers
Downsides:
- not secure
- can be unreliable
- slow adoption of the newest version
That was a short list and comparison of different kinds of connectivity that you can use for your connected device. It's not a full list, there are some more technologies available, but they're not so popular.
If you'd like to get more technical details on technologies listed above, or you need consulting on your IoT project, send me an e-mail.
