Designing with an LPWAN module

Article By : John Koon

LPWAN technologies have greatly advanced in recent years. The two leading competitive LPWAN technologies today are LoRaWAN and LTE. LoRa Alliance, the organization behind the LoRaWAN specifications...

Low-power wide-area network (LPWAN) technologies have greatly advanced in recent years. The two leading competitive LPWAN technologies today are LoRaWAN and LTE. LoRa Alliance, the organization behind the LoRaWAN specifications, has increased in membership numbers. At the same time, LTE carriers such as AT&T and Verizon have developed complete LTE device certification programs. LPWAN is mostly suited for remote applications with no human interaction in which long battery life is desirable. Depending on the applications, some devices can operate up to 10 years without a battery change. Smart parking, asset tracking, animal health monitoring, and customer service automation are among the growing number of LPWAN applications.

LPWAN applications
Looking for a parking space on a busy street can be both time-consuming and frustrating. Smart parking spaces are equipped with underground sensors. These sensors connect to apps that allow users to pinpoint the exact location of a parking space without driving around aimlessly. Connected to an LPWAN network, these sensors can be maintenance-free for multiple years without human attention.

Real-time asset tracking using an LTE network offers convenience and saves costs. For example, cargo equipped with LTE devices provides real-time location data to the shipping company and its clients. Being able to track the whereabouts of valuable assets, such as medical supplies, makes for peace of mind.

Another popular application uses LoRaWAN to monitor farm animal health by detecting movement patterns. A healthy animal is more active than a sick animal. When an animal is sick, it tends to lie down and rest or not move around as much. With real-time reporting, the owner can address the issue quickly.

Finally, LPWAN can also be used to improve customer service. For example, a propane customer may be located far away from the supplier. Equipped with an LPWAN device, the level of propane can be tracked on a real-time basis. When the level drops to a predetermined threshold, signals are sent to the supplier for a new refill automatically without interrupting the customer. Real-time data prevents situations in which propane runs out.

So you are looking to do a new design
LoRaWAN uses an unlicensed spectrum, which does not require the user to pay a license fee. LTE users, on the other hand, must pay a monthly license fee to an LTE carrier or operator for the applications.

In designing a network, developers usually go through the following steps. These steps are conducted in-house as well as by third parties, depending on the project requirements and the experience level of a company’s developers.

  • Defining a product specification and prototyping (usually conducted internally)
  • Initial product performance testing against the product specification (usually conducted internally)
  • Obtaining required certifications (usually conducted internally and externally)
  • Final testing and product release (usually conducted internally)

Why obtaining the required certifications is important
There are two LPWAN product development aspects. The first aspect relates to product performance, such as how fast it performs and/or how much power it requires. The second aspect relates to interoperability with an external network provided by, say, an LTE carrier. Carriers in different countries require certification to ensure that the LPWAN devices will perform according to the carriers’ network specifications. At the minimum, it will require that the device not introduce unwanted electrical harmonics. Such harmonics cause electromagnetic interference to the network. Additionally, the carriers want to make sure that the devices’ radio frequency (RF) works properly. Certification is critically important. Without certification, by law, an LPWAN device supporting licensed spectrum will not be allowed to sell into that particular region. The LoRa Alliance, the organization behind LoRaWAN (unlicensed spectrum), also requires LPWAN devices to be certified to ensure interoperability.

There are two levels of certification requirements.

At the government level, there are the FCC (North America) and CE (Europe). Then there is cellular telecom general certification, as required by various network carriers and consortia. They include the following:

  • PTCRB from the Cellular Telecommunications Industry Association (CTIA) (North America), with Verizon, a non-member, as an exception
  • Global Certification Forum, or GCF (Europe and Asia)

The CTIA in North America initiated the PTCRB certification in 1997. PTCRB International Mobility Equipment Identity (IMEI) numbers are used to track mobile, IoT, M2M devices, and modules for certification purposes. The PTCRB covers the certification requirements by carriers such as AT&T, T-Mobile, and Canadian networks. The PTCRB certification ensures that the device operates at the right RF and that the SIM card interfaces are designed correctly.

Verizon has its own certification process and is not part of PTCRB, so devices requiring Verizon certification need to go through a separate Verizon Open Development Initiative (ODI) certification process.

The GCF, established in 1999, provides certification of mobile and cellular devices, including IoT devices. Its purpose is to ensure global interoperability, primarily in Europe and Asia, using 3GPP technologies, including GERAN (GSM), UTRAN (UMTS), and E-UTRAN (LTE).

Designing with an LPWAN module
Many factors impact the total cost of certification. The complexity of the device, developers’ experience, and pre-certification preparation play a part. The following estimates in American dollars are for references only:

  • The FCC or equivalent agency tests focus on RF design to ensure that its radiation does not affect other equipment. ($2,000 to $6,000)
  • The PTCRB certification ($20,000 to $50,000, depending on the device type)
  • Verizon ODI certification (up to $150,000)
  • GCF certification ($20,000 to $50,000, depending on the device type)

Additional costs will be incurred if the device does not pass the first time. The certification process is so expensive because designing a new network has a learning curve. Unless the developers have carried out an earlier certification(s), predicting how much time it will take is difficult.

For module suppliers, however, it is a different story. Once the modules are certified, they will be sold over and over again. Therefore, the return on investment is much better than that which can be gained by an individual developer company. For a developer, using pre-certified modules can potentially save a great deal of time and effort. The pre-certified module option avoids going through the certification process from scratch. The end device still needs to be certified, but it is a much simpler process.

cloud-LPWAN

LPWAN modules are used in products such as sensors, devices, and sometimes gateways. (Image: Nimbelink)

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