26/07/2020

How to Choose an Internet of Things Protocol for Remote Monitoring

Ethernet Internet of Things Connectivity options

There are several factors that will drive the implementation of Internet of Things (IoT) applications and probably the most important is the communications protocol used. Monitoring and control networks need to be able to collect reliable data from a vast number of devices on demand, and securely. Ethernet is still the ‘go-to’ protocol but there are newer technologies to consider specifically developed of IoT applications.

What is Ethernet?

The term ‘Ethernet’ refers to a family of computer networking technologies associated with IT networks, including local (LAN) and wide area (WAN) networks. Introduced in 1980 and standardised in 1983 as IEEE 802.3, Ethernet grew rapidly to replace other LAN technologies including Token Ring, FDDI and ARCNET. The Internet Protocol (IP) is commonly carried over Ethernet (cable and Wi-Fi) making Ethernet one of the key Internet technologies.

For Internet of Things (IoT) applications, Ethernet is sometimes overlooked. This is because the common view of the IoT is that connected devices must be ‘wireless’ and not connected via an RJ-45 CAT 5 or CAT 6 cable.

Cabled Ethernet, dependent upon the networking hardware infrastructure in place, can provide high-speed encrypted data transmission on a volume scale and should be the primary choice for Industrial Internet of Things (IIoT) applications. Ethernet can also provide Power over Ethernet (PoE) to connected devices and remove the need for separate AC (alternating current) power supplies.

Wi-Fi Networks

A wireless LAN (WLAN) is a computer network that uses wireless communication to form a local area network (LAN). Also referred to as Wi-Fi or a Wi-Fi network, the technology is widespread, especially in public areas or where many portable devices and computers must be connected to a network without an Ethernet cable.

Wireless Ethernet provides high bandwidth access and encryption to the Internet via gateway devices. Most organisations and businesses will offer both private (employee only) and public Wi-Fi networks based on IEEE 802.11 standards.
Wi-Fi though is not without issues compared to cabled Ethernet networks. Typical issues can be signal strength, interference, noise & radio standard compatibility and security are issues often associated with wireless applications. These mean that care must be taken when looking to install IoT applications within a building to ensure that there is significant network coverage for the connected devices.

For more information on IEEE 802.11 standards see: https://www.networkworld.com/article/3238664/80211-wi-fi-standards-and-speeds-explained.html

GPRS / LTE Communications

GSM stands for the Global System for Mobile Communications and is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe the protocols required from second-generation digital cellular networks for mobile phones, tablets, and other connected devices. GSM networks use General Packet Radio Service (GPRS), a packet oriented mobile data standard.

For IoT applications, GSM is often overlooked and especially when there are alternative Ethernet or Wi-Fi connectivity solutions. 3G and 4G technologies do not provide the speed of Ethernet or Wi-Fi but GPRS is a reliable interface and can be suitable for applications where the data usage is low. Mobile usage and coverage are well-established in most countries and 5G is set to revolutionise mobile communications and potentially IoT device connectivity.

GSM will however be around for some time due to its wide adoption. Though the technology provides low-speed bandwidth, it does allow the use of classic Ethernet IP communications (http or https) and a classic client/server configuration to ensure data transmission. GSM also does not require allocated communications ports or SSL security.

LTE (Long-Term Evolution) is a standard for wireless broadband communication. LTE can provide increased capacity and speed and uses a different radio interface with core network improvements. The principle differences between GSM and LTE is that GSM provides cellular and data transmission, and LTE provides data transmission only.

LTE is perhaps more applicable to IoT applications than GSM, but both can be ideal for mobile applications. This is because of their ability to automatically re-register themselves at the strongest point of connectivity to their registered mobile network, without loss of connection when in data transmission mode. LTE and GSM also allow the sending of data to any IP address. The advantages make GSM and LTE superior to other low-bandwidth communications networks including Lora and Sigfox. However, whilst GSM and GPRS networks are mostly unified worldwide, LTE networks are less so with regional bandwidth and protocol variations.

What is NB-IoT and LTE cat M1?

NB-IoT and LTE cat M1 are IP-based networking protocols that can be used in Lora and Sigfox applications. The NB in ‘NB-IoT’ refers to Narrowband with NB-IoT being a subset of LTE cat M1. NB-IoT is designed exclusively for IoT applications. It as a limited bit rate of less than 250kPS download and less than 20kps upload, and limited data volume transmission at a bandwidth of 200kHz.

NB-IoT provided limited switching between connection points. If NB-IoT has at least some connectivity, the data message is transmitted. However, data can be easily ‘lost’ in a mobile network as the communication is conducted after a UDP/IP unverified protocol. NB-IoT is therefore primarily suitable for stationary applications with high energy efficiency requirements.

LTE cat M1 supports Voice Over LTE (VoLTE) and has a transfer rate of up to 1MB/s. LTE Cat M1 can switch from one wireless cell to another and is suitable for mobile applications including telematics. However, data volumes must be kept within the bandwidth and VoLTE is more used for voice messages than for calls.

What are LoRa and Sigfox?

LoRa and Sigfox are two communications interfaces developed specially for IoT applications.

LoRa stands for Long-Range and is a low-power wide-area network protocol developed by Semtech, the founding member of the LoRa Alliance. LoRa is a wireless technology that uses the 868MHz bandwidth and a data rate from 0.25 to 50Kbps. The technology is based on spread spectrum modulation that makes LoRa resistant to interference. LoRa provides two-way communication and can switch between connection points. However, it is complex in terms of parameter setup.

Sigfox is another wireless technology that can be used to connect low-power devices including electricity meters and wearable technologies. Sigfox also operates at 868Mhz and is suitable for short-range (e.g. domestic device controls) and W-Mbus (Wireless-MBus) wireless sensor technologies. Sigfox is a lightweight protocol with a low baud rate of 100 or 600 Bits per second and therefore low power consumption.

LoRa and Sigfox provide secure data transmission using AES128 and multi-bit authentication and are ideal for short message types including temperature and fault status.

LoRa and Sigfox differ to Ethernet communications in their operational reliability. Ethernet is 99.9999% reliable, whereas LoRa and Sigfox have a 5% default error rate. This is due to the lower broadcast times and potential for overload. Data transmission errors are solved at the next time slot and are not resolved by the devices themselves.

Low Power WANs

NB-IoT, LTE cat M1, LoRa and Sigfox IoT networks are often referred to as a Low Power WAN or LPWAN. Their low power usage allows connected devices to be powered from batteries (or accumulators) with 5-10 working lives based on limited data transmission rates of say once per day.

LPWAN networks also use a thin communications protocol and this prevents remote configuration or diagnostics for the connected devices or sensors. LPWAN technology requires further development if it is to achieve the wide adoption achieved by Ethernet-based networks.

Network Communications Protocol Comparison Table

Technology Frequency Bandwidth Bit Range Range Target Server Capacity Mobile App Notes
BT 2,4GHz/ 5GHz 1MHz max 1Mbit 10-100m User No limits Limited
Wi-Fi 2,4GHz/ 5GHz 40MHz max 150Mbit 10-100m User No limits Limited
GSM/GPRS 800/ 900/ 1800/ 1900MHz 200kHz 172kbit 10-15km User No limits Yes
3G (UMTS/ HSPA+) 800-2100MHz 5MHz 384kbit 5-10km User No limits Yes
LTE 450-3500MHz 1,4MHz 150Mbit 5-11km User No limits Yes
LTE cat M1 450-3500MHz 1,08MHz 1Mbit 5-15km User No limits Yes
NB-IoT 800MHz 200kHz 200kbit 5-15km User transmitting time 1% per hour Limited High latency 1.6 –10s
LoRa 433/ 868/ 913/ 915MHz 125/250kHz 50kbit 5-15km Operator transmitting time 1% per hour Yes
LoRaWAN 433/ 868/ 913/ 915MHz 125/250kHz 50kbit 5-15km Operator/ User transmitting time 1% per hour Yes
Sigfox less than 1GHz 200kHz 100/600bit 10-50km Operator transmitting time 1% per hour, max 140 messages/ day no max. 216byte/hr effective
Ethernet 10Mbit-10Gbit User No limits no

Summary

The Internet of Things relies on connectivity no matter what the communications protocol or where the data is processed, whether ‘on-premise’, in an Edge datacentre or remotely by Cloud servers. Ethernet is the accepted standard, but 5G-based Wi-Fi and new IoT specific protocols are developing rapidly. Each has their own space and will meet different needs for security, data size and transmission speeds, and energy usage.

Businesses and organisations looking to deploy IoT monitoring over their estates or to offer as a service to clients, will require an environment monitoring software platform that is device agnostic and capable of communicating with multiple devices and protocols simultaneously.

Their chosen software platform must be capable of using an array of monitoring devices and protocols ranging from traditional Ethernet to 5G-based Wi-Fi and IoT specific protocols including LoRa and Sigfox. Any deployed monitoring software should also be future proof, as communications standards evolve, and new IoT protocols are developed.

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