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Wireless M2M solutions have traditionally only had three different technologies that they could rely on for communication. They could accept the limited range of standards-based local area technologies (such as Wi-Fi, ZigBee, and Bluetooth), pay the costs for wide-area cellular technology, or accept the smattering of long-range proprietary solutions. A new market is now emerging with the deployment of Low Power Wide Area Networks (LPWAN). LPWANs are expected to bridge the gap between current LAN and WAN technologies to allow for low-cost machine-to-machine communication for the emerging Internet of Things (IoT).

During Mobile World Congress in Barcelona in March 2015, the LoRa (Long Range) Alliance approved the first technical specification for LoRaWAN, a leading contender for the LPWAN market. LoRaWAN details how low-powered modules can utilize sub-GHz frequencies to communicate through multiple gateways to a network server. This system of end nodes communicating through a gateway infrastructure to a centralized network authority is intentionally analogous to current cellular networks. The LoRa Alliance is led by industry leaders such as Semtech, IBM, Cisco, Actility, Microchip, and Laird and is designing a new type of network for M2M communications to enable these small nodes to communicate through a public or a private network. LoRa transceivers are capable of bidirectional communication in ranges equal to or greater than current LTE technology, but at 1/100th the power consumption. This makes LoRa ideal for battery-powered sensors and controllers looking to take advantage of an IoT infrastructure. The LoRa Alliance already has multiple members focused on providing public and private networks such as Link Labs and Actility, and hardware providers such as Link Labs, Microchip, and Laird in production or developing module technology to act as end nodes.

Figure 1: LPWAN has the potential to cover a city with only a few gateways (Photo Credit: LoRa Alliance)

LPWAN is expected to see wide use in markets such as Smart Metering, Smart Cities, Tracking, Agriculture, Smart Home, and Smart Environmental monitoring. These markets are primed to launch new types of sensors and controllers which can take advantage of LoRa’s always-on infrastructure and the low power consumption for end nodes. In just these markets, the total market size for wireless connectivity is expected to be over a billion dollars. The entire IoT market is projected to be over 20 billion devices by 2020 and LPWAN is poised to take up to 40% of the total IoT market. Through the use of public networks where users pay for access from their end node to a central network server and the Internet beyond that, LoRa will be able to approach many of these markets concurrently. The long range of the LoRa gateways allows a network provider to cover a large metropolitan area with only a few gateways; this will allow them to utilize the network for smart metering, smart cities, tracking, and other markets simultaneously.

Besides LoRa, there are competing technologies such as the privately owned Sigfox, the privately owned and the standards-based Weightless (which was previously focused on public networks using the TV White Space). Traditional cellular providers are also delivering WAN for M2M utilizing LTE while the cheaper and lower data rate solutions such as 2G continue to be phased out. However, LTE is often too power hungry for M2M communications and next generation specifications which will target IoT/M2M are still a few years away from widespread adoption.

LoRa utilizes direct sequence modulation in primarily the unlicensed frequencies reserved for ISM (Industrial, Scientific, and Medical) such as 868 MHz in Europe and 902 MHz- 928 MHz in the United States. This allows for network operators to deploy networks without the costly burden of frequency licensing. The LoRaWAN technical specification utilizes many unique features to enable long range, low power, low data rate communications while adhering to all regulatory requirements and while allowing for high density public networks.

Figure 2: LoRaWAN network diagram (Photo Credit: LoRa Alliance)

The LoRaWAN architecture consists of three main components. The end nodes are the low-data rate applications which are sensing and controlling the world. These communicate to one or more gateways which aggregate the signals and forward them to a network server. The network server is responsible for authenticating end nodes and is responsible for negotiating the end-to-end encryption which is part of the LoRaWAN specification. In a private network the network server may be responsible for directly working with the data from the end node. In the case of a public network, it could forward the information to an application server which is ultimately responsible for processing the data from the end node.

As a developer, the vision is to provide a quick time to market through the use of public networks. A developer with a product idea, such as a tracker for bicycles in a bicycle sharing system, would work with a module provider to integrate a LoRa technology into their finished product. Modules are certified for interoperability by the LoRa Alliance to ensure it will work with any public or private LoRa network. The developer would then select a service provider to provide network access for their node and thus allow their end node to communicate directly to their application server where the asset information could be synchronized with their customer base to track the bicycles in real-time across an entire city. LoRa's long range, seamless roaming, low cost, and low power make it ideal for such applications which require range beyond the local area network.

For developers of more industrialized solutions, they may decide to deploy their own private network to ensure network access at all times and providers for higher levels of service. LoRa's distributed network architecture allows developers of distributed control systems (DCS) to provide redundant gateways to ensure no single point of failure. Furthermore, the network server can be cloned to ensure end nodes are always able to access the network, even in the event of hardware failures. These same features are available on the public network, though the infrastructure is shared with other users.

LPWAN is poised to provide a new communication model for long-range, low data-rate, battery powered applications for M2M. It provides a solution for developers looking for the access provided by current cellular technologies at the low costs associated with current local area technologies. The market for LPWAN is expected to be fairly crowded with proprietary, standards-based, and LTE solutions, all of which will compete for market share. The LoRa Alliance is well positioned with LoRaWAN ratified and a broad collection of members. Success will be measured by the density of public and private networks that cover urban and rural areas to provide access for the low-cost end nodes.

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