Here is my solution for rural infrastructure comprising four relatively "off-the-shelf" components. It is specific to New Zealand and to the telecommunications carrier Spark NZ
in terms of radio frequencies. A subsequent post will describe the application layer which sits upon this infrastructure.
This is the solution I have in place at our family bach on a remote island in the Marlborough Sounds
. The island has no infrastructure or utilities and is nominally outside the coverage area of the cellular carriers. There are no roads, access is by air or by sea. The bach is self-sufficient by necessity with independent energy, water, waste, fertilisation, irrigation, security and other systems. It is unoccupied for long periods throughout the year.
The challenge is to obtain reliable outbound connectivity. The opportunity is to introduce automation such that the bach can operate fairly autonomously whilst unoccupied, and technologies to afford manageability when it is.
Bill of Materials:
I'll describe each of the components below. The following diagram depicts the interconnection topology between the four discrete network segments they provide:
- Cellular for Internet access and phone connectivity;
- WiFi for portable devices;
- Wired for devices connecting via data cables and;
- LoRa for Internet of Things sensors and actuators.
- Lintratek Repeater (Cellular Network)
The steep geography and sparse population of the Marlborough Sounds makes provisioning WiFi or cellular coverage challenging and uneconomical. Conversely satellite solutions such as Farmside are expensive, with low bandwith caps and high latency.
Fortunately for us a site survey of radio spectrum (conducted by me through the excruciating trial and error process of waving an antenna around) discovered we could obtain a connection to a Spark NZ cell tower by precisely tuning the angle on a 24 dBi antenna. With the introduction of a Lintratek repeater we managed to amplify the sensitivity by 62 dBi, achieving connection stability and reliability for UTMS Band 5 at 850 MHz. The same cell tower also transmits LTE Band 3 at 1800 MHz and the hope/plan is to upgrade by swapping out the repeater.
On the internal side, a separate antenna provides distribution to clients on our side of the network. Cell phones with a Spark account operate nominally (cell phones with accounts at other carriers do not.) The demarcation is a generic 3G/WiFi router servicing the internal network segments.
- 3G/WiFi Router (WiFi Network)
Not much to say here as this generic 3G/WiFi router is just a gateway for the internal networks to access the outbound cellular network. It does provide WiFi though, for portable devices such as non-Spark NZ cellphones.
- PoE Switch (Wired Network)
Not much to say here either as this switch provides generic data connections over UTP. It does offer Power over Ethernet (PoE) however, for devices such as security cameras which can be powered in this manner.
- Raspberry Pi (LoRa Network & Serial Interfaces)
The Raspberry Pi is a server. I'll describe the application layer in a subsequent post but broadly for the purposes of this post, its core services are openHAB and OpenEnergyMonitor for automation and management, and control of the energy system which it connects to via serial interfaces.
With the introduction of a RAK831 daughterboard, the Raspberry Pi has also become a LoRa gateway to which sensors and actuators can connect. I chose the AS923 variant to comply with New Zealand's Radio Spectrum Management and for compatibility with the Spark NZ LoRa network.
We're introducing a variety of IoT sensors to measure and report fluid levels, gas flow, water quality, moisture, humidity, temperature, wind, sunlight, motion et cetera and corresponding IoT actuators such as servos, relays and solenoids to respond and control the physical environment.
In synopsis, these four relatively inexpensive components provide a comprehensive infrastructure to connect to the Internet and facilitate the operation of a rural property where the aim is to measure, report, automate, manage and if necessary escalate, with potential applications falling broadly within the categories of home automation
and precision agriculture
. The diagram below illustrates the devices utilising this infrastructure and a subsequent post will describe the software and integrations for automation and management.
-SRA. Auckland, 20/xi 2018.