Written by : Deepaknath Tandur, January 2016
Low-Power Wide-Area Network (LPWAN) is a type of wireless communication infrastructure network that targets long-range connectivity with thousands of very low data rate objects or things. These objects are small nodes or sensors that can operate on battery power for several months and years. Some of the common application examples are fire alarm sensors, gas detectors, water meters, parking sensors, etc. According to Machina Research, by year 2024, about 14% of 27 billion machine-to-machine (M2M) connections will be using the LPWAN technology. Thus, LPWAN will represent an important enabler for IoT solutions in the future.
In this article, we will look at some of the prominent LPWAN solution providers existing today. The major LPWAN players are currently involved in deploying their own outdoor network infrastructure. These networks exist in parallel to the cellular infrastructure and may utilize the same cell towers. The difference here being that these networks operate on unlicensed wireless spectrum band of sub-GHz frequency space (around 868 MHz in Europe and 915 MHz in US) and 2.4 GHz frequency space (available universally). These networks are able to provide coverage to thousands of nodes over very large distances, sometimes greater than 20 KMs though the data rate in this case will be in the order of few bytes per second. LPWAN networks mainly handle upstream traffic for monitoring the data, though downstream traffic is also feasible, sometimes with certain limitations. The nodes spend most of their time in sleep state and wake up mainly to transmit the data thus leading to a long battery life.
Sigfox: Sigfox says it has presence in 14 countries with connectivity to roughly 7 million devices worldwide. The majority of the coverage is in Europe and lately it has presence in the US as well. Sigfox estimates that for a geographical location like the size of California it only needs around 1,500 microcells compared to something like 20,000 for a traditional cellular network.
Sigfox charges customers on subscription basis where the customer pays few dollars a year per device for connectivity to their network. More than a dozen companies currently build Sigfox receivers based on the company's free-to-use development kit. The company broadcasts its signal through briefcase-sized base stations covering 20-30 kilometers in unlicensed sub-GHz spectrum. The network uses ultra-narrowband (UNB) based transmission to do wide-area IoT networking and it can provide capacity for thousands of devices to exchange information. The network can handle up to 12 bytes of upstream message data per device with a maximum of 140 messages per day. The downstream acknowledgements are limited to 8 bytes of data per message with a maximum of four messages per device per day. The messages are forwarded to the customer’s application using Sigfox’s API.
Ingenu: Also formerly known as On-Ramp wireless, is one of the prominent LPWAN players in North American region. Ingenu has built over 38 private networks in 20 countries. These private networks are mainly deployed in the Utility and the Oil and Gas sector. Apart from building private networks, Ingenu also plans to deploy public networks in various cities across the US under the name of “Machine Networks”.
Ingenu itself provides end-to-end solution to the customer. This includes access points, end nodes devices along with the other associated hardware and software. The customer’s device is finally interfaced with the end node device. The data rate is in the order of bytes per second and nodes have a battery performance of up to 15 years. The network operates on 2.4 GHz spectrum and this provides Ingenu the advantage of deploying the network worldwide with enough bandwidth availability. The network can reportedly cover about 70 square miles per tower. Ingenu says that their network can cover about 70 percent of the U.S. population with 619 towers, that same footprint on Sigfox would require more than 43,000 towers and LoRA (next section) will requires more than 10,000 towers.
LoRaWAN: Unlike Sigfox and Ingenu proprietary solutions, LoRaWAN is a communication standard for LPWAN. LoRa Alliance that includes companies such as IBM, Semtech, Linklab, are supporting LoRaWAN’s standardization activity. LoRaWAN is a media access control (MAC – layer 2) layer protocol designed for large-scale networks. It uses LoRa physical layer (PHY – layer 1) modulation format owned by Semtec Corporation. OSI layer 2 and above functions that include gateways, repeaters, central servers, end devices, data exchange mechanisms are then the function of systems like LoRaWAN.
LoRaWAN network architecture is laid out in a star-of-stars topology in which gateways act like a bridge relaying messages between end devices and a central network server. Telecom companies integrate gateways on towers and provide the network service. The end-devices are embedded with LoRaWAN protocol in order to easily connect with the service provider. The network operates on sub-GHz frequency space and several companies are now providing solutions. Dual-mode modules that support both LoRa and Sigfox are now also available in the market
NB-IOT: Narrow-Band IoT (NB-IoT) is a LPWAN technology standardized by the 3GPP telecom body. There are other telecom evolutions as well, but NB-IOT is the most prominent one. This technology will reuse both GSM as well as LTE spectrum. The standard is currently in progress and it going through development processes and test deployment. Leading telecom and chip vendors are supporting its development. Pilots of pre-NB-IoT technology are currently underway and the first pre-commercial trials of the technology are likely to begin in the second half of 2016. Commercial NB-IoT deployments are expected to be rolled out in 2017. Analysts view NB-IoT as a direct competition to proprietary and LoRa based LPWAN solutions. NB-IoT is expected to bring in the required inter-operability and scale for a worldwide deployment mainly due to the support it receives from 3GPP.