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IoT connectivity is rapidly growing in capabilities and scope. The LPWAN landscape consists of similar technologies which vary in terms of their functional and optimal use cases. The specifics of each protocol in action can vary per region, cost, and availability. They are geared for different use cases according to specifics like latency, speed, the capacity for one-directional or bidirectional links, and security. However, there’s plenty of situations when different protocols can serve the same use case equally well.
It’s worth noting that these protocols are ever-evolving, especially with the rollout of 5G and preparation for 6G. But, here are the chief characteristics of each protocol in plain language:
LoRaWAN is a Media Access Control (MAC) layer protocol built on top of LoRa modulation. The layer defines how devices use the LoRa hardware. The LoRa Alliance developers and maintains the protocol. LoRaWAN has loads of advantages: end devices can work in low power with a lifespan of up to 10 years on a single coin cell battery. LoRaWAN gateways can transmit and receive signals over 10 kilometers in rural areas and up to 3 kilometers in denser urban areas. It also works well in indoor-multi floor buildings. Roaming is handled neatly across networks, and you can update firmware over the air.
The networks are high capacity. AES-128 encryption ensures end-to-end security. The spectrum is license-free, meaning no fees to deploy a LoRaWAN network. LoRaWAN has a mammoth ecosystem of antenna makers, device makers, gateway makers, and developers. The number of LoRaWAN use cases is vast and spreads across every industry. Think smart farming,m wearable tech, cold chain monitoring, smart bike tracking, and animal conservation.
There are, however, a few disadvantages of LoRaWAN. The payload is limited to 100 bytes, making it unsuitable for large data payloads. It’s intended for irregular rather than continuous monitoring, such as smart bins vs medical equipment. The open frequency may result in interference.
LoRa (Long Range) is a radiofrequency carrier signal owned by Semtech. It’s based in the PHY later of the telecoms device and uses a modulation technique known as chirp spread spectrum (CSS). Information is encoded on radio waves (not dissimilar to the way dates communicate).
In other words, LoRa is the modulation technique used in LoRaWAN, and LoRaWAN is a wireless network.
Founded in 2009, Sigfox is a French company that uses proprietary technology in its extended cellular wireless network to transmit data from low data rate applications. Sigfox utilizes the 192KHz Ultra Narrow Band (UNB), Unlicensed ISM Band, 868 MHz (Europe), and 915 MHz (USA).
Sigfox is widely deployed across over 60 countries and is suitable for long-life (5-10 years) battery-operated use cases. Sigfox is efficient – its protocol uses about 26 bytes to transport 12 bytes of data, where a conventional wireless IP stack uses about 40 bytes. As there is less data to be transmitted, less energy is needed, enhancing battery life. Sigfox has many use cases, such as water metering, air quality monitoring in buildings, asset tracking, and underground scenarios like water leak detection.
However, Sigfox is effectively uplink only. Downlink is restricted – it’s adequate to configure device parameters but not update device firmware. Therefore, it’s typically unsuitable for high data rate applications.
Narrowband IoT (NB-IoT) is a wireless telecommunications technology standard developed by 3GPP, the international standards body responsible for all major mobile telecommunications standards such as 4G LTE (4G) and 5G NR (5G). NB-IoT uses the same sub-6 GH wireless spectrum as 4G LTE. It was developed specifically for IoT. It’s designed for long-term low energy, relatively low-speed use cases such as home automation, agricultural and cattle monitoring, and pipeline management.
NB-IoT’s large-signal repetition provides coverage far superior to other cellular technologies. It can connect to cellulite networks even with numerous similar devices nearby and functions inside buildings, remote areas, and underground. It’s worth noting that NB-IoT is built on 256-bit 3GPP encryption, whereas LoRaWAn has a lower AES 128-bit encryption – an essential difference for security-critical applications.
LTE-M (also known as LTE Cat-M1 or Long Term Evolution (4G), category M1) is an LPWAN radio tech standard developed by 3GPP for M2M and IoT applications. This makes it possible for IoT devices to connect to a 4G network on batteries and without a gateway. Like NB-Io, LTE-M is suitable for low-cost, low-power devices that need extended coverage. However, its data rates are faster than NB-IoT at a lower latency. This makes it suitable for voice communications and applications like precision tracking and emergency communication that require real-time communications.
However, most network operators prefer NB-IoT networks over LTE-M, meaning their is typically better coverage in spaces like warehouses and underground where signal loss can lead to connectivity problems and real-time applications like healthcare. NB-IoT and LTE-M can both operate with new 5G technologies, like 5G New Radio.
Symphony Link is a Link Labs is a LoRa Alliance member. While they use the LoRa chip, they use a proprietary MAC software layer on top called Symphony Link instead of LoRaWAN. It’s used in situations such as lock control, demand response, alarm systems, and physical security.
Symphony Link is great for over-the-air updates such as security issue patches, new features, and bug fixes.
You might wonder why you should use Symphony considering the size of the LoRaWAn ecosystem? According to LinkLabs, there are several limitations for private networks, such as significant difficulty in updating devices and that only one network can operate in areas without interference. According to Link Labs, LoRaWAN is an asynchronous ALOHA-based protocol with limited acknowledgments, meaning packet error (PER) rates over 50% are typical. By comparison, the Symphony Link MAC acknowledges every message both up and down.
LinkLabs assert that LoRaWAN is designed around a 1% duty cycle limit driven by European ETSI requirements, preventing LoRaWAN from being used in systems that need to send lots of data over time. By comparison, Symphony Link makes it possible to update firmware over the air quickly and easily.
Weightless is an open standard that operates in the sub-1 GH unlicensed spectrum, developed to faciliate interoperability between manufacturers. It was created by the Weightless special interest group (SIG) in 2008. It operates from an open-source model (the website is effectively defunct). This suggests that Weightless exists mostly in theory than practice – the SIG intended to limit patents to suitably qualified devices, but the group seems largely inactive.
There are, however, three versions of Weightless, with most activity by a company called N-Wave.
Weightless-N transmits within narrow frequency bands using a frequency hopping algorithm. It coexists well with other radio technology, and security is enhanced using a 128 bit AES algorithm. However, it is only capable of very slow downlinks.
It’s used in the oil and gas industry for temperature readings, tank-level monitoring and smart metering, and smart city use cases like smart parking.
Weightless-P is a bidirectional protocol primarily used in private networks and applications where the control of uplink and downlink data are equally important. However, it lacks the scalability of Weightless-N and is limited by it’s hardware availability.
Weightless-W frequency hops across the terrestrial television broadcast band, specifically using channels not otherwise used for broadcasting.
Anthony Sayers, Director of IoT Ecosystems & Partners, Davra
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