Don’t Invest in a Wireless Connectivity Technology for Your Farm Until You Read This!
Author: TechMyFarm Date Posted:8 January 2019
It has never been more important than now to be investing in sensing, monitoring and automation for your agricultural operation. Shortages of labour, increases in the cost of the available labour and input costs are on the rise!– It is critical that you begin planning and implementing your smart farm strategy to maximise your profits.
One of the most critical elements in a connected smart farm is how to connect all the sensors, controllers, other smart devices and cameras on your farm. (things)
With so many IoT (Internet of Things) Wireless connection options out there and each proponent claiming that theirs is the best, how do you know which one, or which combination of systems to use? This article will highlight some usable options and applications for agriculture. (We say usable as there are many protocols and wireless technologies that have been developed but are not really commercially available at an affordable price for agricultural deployment, or there is very limited certified usable hardware.
The other important factor to consider when choosing a wireless technology is the protocol, platform and/or software that will be used to communicate with your smart things. Not all software, platforms and systems are compatible with all wireless technologies, and sometimes the cost of using specialist converters and gateways can lead to complex and expensive systems.
There are various ways to categorise wireless technology and devices that make up a wireless network. Perhaps the easiest starting point is to divide them into two categories.
- High powered and
- Low powered.
High powered devices generally are always ‘on’, continually communicating, are capable of sending and receiving large amounts of data (such as video streaming) at greater speeds with faster processing components and larger memory. Hence these devices have a higher power demand. Examples include standard Wi-Fi (802.11ac or Wi-Fi 5), Long-range Wi-Fi and always ‘on’ full-service 3G/4G.
Long Range Wi-Fi
Some readers may not be familiar with long-range Wi-Fi. Unlike standard Wi-Fi that you are accustomed to in your home or office, that can have a range at best, up to one hundred metres, long-range Wi-Fi is directional and can easily reach (with high throughput) distances of over 20 km with low-cost radios and over 100 km with higher cost (but still affordable) radios. Think of it as a virtual cable. Long-range Wi-Fi networks can be deployed in point to point or point to multipoint fashion.
Whilst it is true that line-of-sight is important for successful links, common obstacles in agricultural settings such as trees, hills and sheds can easily be overcome by mounting radios on existing high infrastructure such as silos, tanks, sheds, RTK/UHF towers and by using effective repeater points (which may not always be in a straight line). All such devices can easily be powered by remote solar and battery kits without the need for mains power.
Unlike 3G/4G where firstly your device needs to be in range of the mobile service provider and secondly requires a sim card and ongoing fees, Long Range Wi-Fi is easy to administer is extremely reliable and you can create your own easy to manage network at speeds that far exceed what you get on your fixed wireless internet connection!
Low powered devices have been developed mainly for use in sensor networks and low data rate requirement applications. The explosion of connected devices through the Internet of things has driven the need for low powered devices that often have a sleep mode function, lower computing power
and memory in order to meet small form factor design requirements and power budgets. This has led to terminologies such LPWAN (Low-Power Wide Area Network) and LPLAN(Low-Power Local area network).
It is important to understand right from the outset that these low-power devices and technologies have a significant trade-off in performance that is unavoidable (at least with most the currently available technology), as these devices in order to meet the low-power budget requirements must use less powerful processes, transmitters and less memory. Most LPWANs are unable to even achieve a data rate of 1 Mbit per second and some even operate at rates much less than this. The advantage is of course that these devices can run on very small batteries (depending on their wake-up and sleep program) for many months and even years without the need for recharging.
One thing to remember is whilst in many cases these devices can be an excellent choice, you must also factor in that not all sensors and communication devices are integrated. If the sensor or thing that is connected to the LPWAN device has a higher power demand it may require a supplementary power source and or recharging options such as a solar panel.
In the LPWAN world there are various ways to categorise the various technologies but as this is not aimed to be a technical document, we will start by dividing them into two categories, A ) Provider and/or Subscription LPWAN and B) private and free LPWAN.
A) Provider and/or Subscription LPWAN
Narrow-Band IoT (NB-IoT and LTE-M)
NB-IoT and LTE-M use unused portions or specially allocated blocks of spectrum on 3g/4g and LTE networks respectively in commercial mobile wireless provider networks (Licenced)
NB-IoT uses a smaller transmission size than LTE-M with downloads being less than 250 kbps and for uploads, it is less than 20 kbps and is suited for non-mission critical and low data devices.
LTE-M allows for higher data rates thus being the choice for more data-intensive options.
Although it may sound like you may have a choice between the 2 types, in a rural situation it will ultimately depend on if there is firstly even a mobile service provider in range and what standards they will offer.
Bear in mind that each connected device will have service and ongoing subscription fees albeit at a low rate, but with 100s-1000s of data points on an agricultural operation they can tally up quite quickly
Sigfox is a subscription service that has its own infrastructure (not cellular) that uses ISM bands (unlicensed) to transmit data over a very narrow spectrum to and from connected objects. Sigfox is for mainly for M2M applications that run on a small battery and only require very low levels of data transfer. Sigfox uses a technology called Ultra Narrow Band (UNB) and is only designed to handle low data-transfer speeds of 10 to 1,000 bits per second. It consumes only 50 microwatts. The network is very scalable that can communicate with millions of battery-operated devices across areas of several square kilometres making it suitable for various M2M non-mission critical applications such as environmental sensors. It operates in the sub-GHz band giving it better penetration through objects and hence giving it a long-range, between 30 to 50 km in rural environments with data rates up to 1000bps
One point to be clear on is that LoraWAN is actually a protocol built on a LoRa chipset. There are other protocols such as Symphony Link (see below) that are also built on the LoRa chipset. However, in most cases when people refer to the LoRa they are talking about LoRaWAN. LoRaWAN operates in the sub-gigahertz spectrum usually at 900 MHz or 800 MHz depending on which country it is being used in. Although line-of-sight improves the range, because it does operate in the sub 1 GHz spectrum it is able to penetrate obstacles than the gigahertz frequencies.
Although LoRaWAN has gained strong support and adoption it is fair to say that it still has some reliability issues such as higher incidences of lost data packets and poor confirmation of delivery. However, in most agricultural settings these can be resolved. LoraWAN can be deployed both in a public, that is a subscription service provider model whereby a business (operator) deploys infrastructure in a given area and then charges accordingly for devices to connect to their network or because it operates in the unlicensed spectrums, private networks can also be deployed which are particularly attractive in agricultural situations
Low Power Satellite IoT
Once considered too expensive with too much latency and not enough coverage the Satellite IoT space is now a commercial reality for selected use cases with more devices (things) being connected to a satellite every day.
B) LPWAN (Private)
Private LoRaWAN is an open protocol that uses exactly the same technology as discussed above but is deployed in a private scenario where gateways and nodes are configured, managed locally and connected to private IOT servers
LoRa Symphony Link
Symphony Link® is a proprietary protocol developed by link labs on a LoRa chipset. According to Link Labs, a key difference is because LoRaWAN is asynchronous, with limited acknowledgments, packet error rates a very common. To quote directly, “Symphony Link acknowledges every message, both up and down. LoRaWAN, SIGFOX and others utilise a ‘spray and pray’ method of message delivery”. Another key difference is the ability to upgrade firmware over the air. As the IOT space is still very much evolving, firmware upgrades are needed frequently, however with many LPWAN technologies it is not practically possible to upgrade firmware over the air and you physically must go to each node to perform the upgrade, Symphony Link, on the other hand, has developed a method where firmware upgrades can be done in a timely manner over the air.
In the LPLAN world, there are literally hundreds of different wireless technologies and protocols and more are emerging each day, some with very specific niche use cases and some with broader appeal that have already enjoyed successful commercial take-up around the globe. Remember when we are discussing LPWAN we are talking much shorter distances some as little as just meters as opposed to the longer range distances of LPWAN.
Arguably the most deployed LPLAN and LPPAN (Low Powered Personal Area Network), technology. It is based on the 802.15.4 standard. This means that whilst the actual transmission distance is small because it be can be used in a mesh configuration thereby passing data to neighbouring devices it can actually become a longer-range mesh network. Although the actual cost of the chips is relatively cheap, the finished certified integrated ZigBee sensor products are often quite expensive. Zigbee has a data rate of 250Kbs
Most people would be familiar with Bluetooth, but Bluetooth LE (low energy) or BLE is a newer standard of Bluetooth optimised for the IoT, making it relevant for sensor networks. BLE like most LPLAN offerings has a sleep/wake functionality. This makes it ideal for IoT devices, which run on batteries and consume a low amount of power. However, a unique point of difference is that some BLE modules available have dual mode feature that will make the device work with Classic Bluetooth which gives extra integration options to other devices.
6LowPAN (IPv6 Low-power wireless Personal Area Network) is Network protocol (as opposed to an IoT application protocol like Zigbee) that can ‘sit on’various physical layers, different frequencies and communication protocols like Wi-Fi, 802.15.4 and sub-1GHz ISM. What does this mean? It means it enables devices to talk to other devices across different platforms. Zigbee devices really can only ‘talk’ to Zigbee devices. Another key feature unlike Ipv4 there is no concern about running out of IP addresses. And speaking about addresses, unlike other IoT setups, a 6LoWPAN sensor device can easily communicate with another node anywhere in the world, as long it knows its address and it is on the internet. This also makes software application development potentially easier.
Although not quite ready it is worth to briefly mention that 802.11 ax or Wi-Fi 6 is close to being ratified and it is likely to have a huge impact on the current IoT landscape with Sleep/wake functionality and other energy saving tweaks. Everybody already knows how to work with Wi-Fi! We will discuss this another time.
What to consider when planning your IoT connectivity for your farm or Agricultural farm?
There are certainly some ‘off the shelf systems’ which take some of the pain from the below decision making considerations out of the equation, but as you delve more into IoT you will soon realise that there is no one size that fits all and you will need to integrate a number of systems.
To help you choose which technology (or at least enable you to get the best results when discussing with your IoT implementer) you may want to deploy for your operation here are some questions and scenarios for you to consider.
- What are you monitoring and what are you controlling?
Do you need just to monitor? Or do you need to control as well? Devices that are just monitoring will usually not need to be too sophisticated whereas if you are controlling, you usually will want some real-time feedback and confirmation.
- What are you protecting?
Any modern farming operation needs to integrate real-time CCTV into their operation for safety, security, checking, decision making, staff training, artificial intelligence, confirmation of operation (sometimes despite having sensors you still need a visual confirmation when the resource is just too valuable, such as buying and taking delivery of water or lift pump operation at 2am! Would you rather check on your cameras on your phone from the comfort of your bed or drive to a site in the middle of the night?
- How important is accuracy and reliability of data?
For example, if you are monitoring soil probes say with 30 minutes intervals, if you miss one or two readings in the day it may not have too big of an effect on your operation. However, consider this scenario: if you had a critical water header tank which you are monitoring the tank level remotely with data being collected every hour what would happen if a leak occurred in the network and you miss that hourly reading? You could potentially lose a lot of water if not all, because of that missed reading! The whole point of using IOT on any smart farm is to protect assets and manage resources efficiently, if the reading was successfully transmitted and you did receive the alert on your phone that the water level had dropped in an unusually fast manner compared to the previous reading, you could potentially still be able to investigate and prevent total water loss but with the misreading, well, it could be very costly.
- What distances do you need to cover?
Will you use High power, LPWAN or LPLAN or a combination of all?
- How will you collect the data?
Will you use local data loggers or be sending everything to a cloud server? Will you need middleware software and protocol format converters? Will you be interfacing with existing systems such as an existing Irrigation controller or scheduler? Always try and chose software that has an API so it is easier to integrate into your complete system.
- Do you have existing power at the site where you want to install a node or base station?
- Will your new system coexist well with an existing system (interference)
- Are you happy to pay subscriptions or would you prefer your own free network?
- Are you willing to persevere with a newer technology?
...for a potential upside of new great features but may have teething problems, or do you want something stable even though it may have limitations and become outdated more quickly?
Do you like your neighbours? It is possible to share a network but not the data, so if you have like-minded operations in your area you could save by sharing communication resources. Just like in cases where RTK towers are 'shared'.
There are a number of LPWAN and LPLAN connectivity options now ready for deployment in farming operations, the reality is a mix of different technologies will be required including Long Range Wi-Fi. Once you know know what devices need connecting and which processes need automating, you can then choose your connectivity mix and work with an implementer to make your smart farm a reality.
Techmyfarm is an efficiency gaining technology company. It is an implementer of IoT technology and solutions for smart farms and the general agricultural sector. Contact us today and let us help you Tech Your Farm.