Low Power Wide Area Network (LPWAN) Technology – Benefits and Testing Challenges

What is LPWAN?

The Internet of Things (IoT) refers to a network of billions of devices connected to the Internet around the world. Common IoT devices include wearable devices and smart home devices. Such applications basically sacrifice some privacy in exchange for certain conveniences. In the industrial field, the advantages of IoT are extremely significant. It can not only improve productivity, reduce costs, and reduce energy consumption, but also allow machines to read massive amounts of data and perform actions based on it. By analyzing the data generated by all IoT devices, you can improve work efficiency or provide better services to your customers. Because you can understand your customers more deeply, you can provide new types of services and expand the scope of your services.

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However, most of today’s wireless technologies are still not up to par with the requirements of the IoT, especially in terms of coverage or battery life.

To meet IoT requirements, you must make a trade-off between data rate, power consumption, and range. To achieve low power consumption, you are forced to sacrifice data rate.

ZigBee, BT LE, and NFC provide short-range coverage at moderate data rates and low power consumption.

LPWAN is a technology that meets both the requirements of coverage and battery life. It provides the longest range with minimal power consumption and only a slight drop in data rate.

Many smart city and smart utility applications, such as smart street lights, humidity sensors, smart metering, and smart parking, do not require high data rates but require very wide coverage. This is where LPWAN can come in handy.

LPWAN Technology: Case Studies

Let’s think about how LPWAN can be used to improve efficiency in wireless smart metering applications.

A utility company is responsible for providing water to all households in a small town. The company has to send people to read water meters from house to house, and the entire process is done manually, which takes a lot of time to travel back and forth. If the company can install water meters in every household, then track water usage wirelessly and send data to the cloud, it will not only save a lot of man-hours, but also effectively reduce costs, allowing the company to focus on other areas. In addition, the utility company can better understand the water usage patterns of its customers and optimize water supply capacity based on relevant data to ensure that every household has sufficient water supply during peak hours.

To track water usage wirelessly, the company must add a small hardware device, an IoT client or agent, to the water meter. This hardware reads the meter data and sends the readings to the cloud at regular intervals. In this case, data rate and latency are not important; the most critical factors are coverage and battery life. Because some water meters are installed in remote locations, basements, or hard-to-reach places, the wireless technology must support a wide coverage area and provide deep indoor coverage. The batteries in the water meters are expected to last more than 10 years.

At this point, the challenges facing these service providers are:

• Connect all water meters installed in remote locations to the cloud via wireless technology
• Ensure that the batteries in these water meters last more than 10 years

To overcome these challenges, the company can adopt LPWAN technologies. These technologies can be broadly divided into licensed technologies and unlicensed technologies, each of which has its own advantages and disadvantages.

LPWAN Technology Comparison

Since cellular networks are expensive, use a lot of power, and require expensive hardware and services, many network providers have turned to unlicensed spectrum (such as LoRa, SIGFOX, and Telensa) to develop their wireless networks. These providers mainly develop their own low-cost base stations for applications such as critical infrastructure and agriculture. They start with small coverage areas and gradually expand the coverage of infrastructure to the whole country or the whole region, and then connect to the cloud through cellular backhaul links.

On the other hand, licensed LPWAN technologies such as 3GPP NB-IoT or LTE Cat-M1 support software updates to existing cellular infrastructure, such as upgrading existing LTE and GSM base stations. By reusing existing 3G or 4G spectrum, they can quickly achieve national and international coverage and deployment. These technologies can support applications that rely on wide coverage, such as vehicle tracking, pet tracking, and logistics. In response to the need for technological evolution, they continue to develop more powerful standards to expand services to other areas, such as mobile communications, roaming, security, and authentication.

Licensed and unlicensed LPWAN technologies have some things in common: high link budgets and long battery life. The main difference between the two is the different ecosystems surrounding these technologies.

SIGFOX is an ecosystem of multiple chip vendors whose products use sub-GHz spectrum bands, with Sigfox managing the protocol and certification. The company offers very small packets (12 bytes) and very low device costs, and is one of the earliest LPWAN manufacturers.

LoRa is a proprietary technology whose chips are provided by Semtech. LoRaWAN is a protocol built on the LoRa technology developed and certified by the LoRa Alliance. LoRaWAN is primarily a media access control (MAC) layer protocol that provides great flexibility for applications, but also poses a major challenge to engineers developing complete solutions.

Narrowband IoT (NB-IoT), LTE Cat-M1 and EC-GPRS are all cellular IoT standards that use a multi-vendor ecosystem of chips or devices from multiple vendors. Like other cellular formats, their certification is managed by GCF/PTCRB. You only need to upgrade the software used by your existing cellular infrastructure to support these new technologies. Although they came out a few years later than unlicensed technologies, they were widely adopted by domestic and international companies after their release to support applications that require wide coverage, such as vehicle tracking, logistics and asset tracking.

LTE Cat-M1 is a simplified version of the existing technology, a revision of LTE technology released by 3GPP. It uses simpler and cheaper chipsets and provides faster data rates than other LPWAN technologies. LTE Cat-M1 can also be supported via software updates to existing LTE infrastructure. Cat-M1 was initially deployed in the United States.

NB-IoT is a new technology released by 3GPP, which can be supported by software updates to LTE or existing RAN infrastructure. Compared with other technologies, its advantages are relatively low device cost and good link budget. NB-IoT was initially deployed mainly in Asia or Europe.

EC-GPRS is an improved version of GPRS that can be supported via software updates to existing GSM infrastructure. It achieves better link budgets than GPRS through signal relaying or retransmission.

Other LPWAN formats include Telensa, Ingenu and Weightless. Telensa is a single-vendor device that uses chips from multiple vendors and operates in the sub-GHz band. The vertically integrated manufacturer focuses on smart street lighting and is beginning to enter the parking sensor field. Telensa has been widely deployed in street lighting applications in the UK, US and Asia. Ingenu is based on its proprietary RPMA technology and operates in the unlicensed 2.4 GHz band. Weightless has three different wireless designs and is managed by the Weightless Special Interest Group (SIG).

LPWAN Requirements and Challenges

LPWAN technologies are diverse and different, but they all share some common characteristics in order to meet the requirements of IoT applications.

• Reliability: Provides 10 years or more of operation without human intervention and can automatically recover after an IoT service interruption
• High density: supports a large number of connected devices
• Low cost: Module price is less than $5
• Excellent battery life: up to 10 years, typically several messages can be sent per day, each containing dozens of bytes, to extend battery life
• Coverage: Can cover hard-to-reach or remote areas

Meeting these requirements is a major challenge for IoT device vendors.

• Reliability: To ensure reliability, device manufacturers must recreate different real-world operating scenarios in the lab or at the production line and test them with a high degree of repeatability. They also need to test adverse scenarios, such as IoT server downtime and connectivity failures, to ensure that the device can recover on its own and does not consume excessive power.
• Coverage: To ensure better coverage, manufacturers need to simulate different RF environments, including remote locations, basements, hidden places, concrete buildings, and industrial environments, where RF conditions vary greatly. Device manufacturers need to perform transmitter and receiver characterization to understand the performance of IoT devices under these different RF conditions.
• Longer battery life: To extend battery life, manufacturers need to analyze the current consumption of IoT devices in active, idle, standby and sleep modes. Device manufacturers also need to recreate various operating conditions, such as remote software updates, repeated transmissions under extreme coverage conditions, and conditions where the device cannot connect to the server to fully understand how much current is consumed in each scenario.
• Low component cost: To effectively reduce component costs, many manufacturers use low-cost components and simplify hardware design. The performance of these components must be carefully characterized to ensure that their reliability is not affected. Careful selection of the right test equipment can help reduce component costs. A complete solution can cover the entire product development cycle from design, manufacturing to compliance testing to help customers significantly reduce capital expenditures on test equipment.
• Support for a wide range of formats: Many manufacturers' products use different LPWAN technologies to meet the requirements of different applications and countries. Therefore, they need a test solution that supports the most LPWAN technologies.
• Acceptance or certification testing: Components using cellular technology, such as NB-IoT modules and Cat-M1 modules, must pass certification and regulatory testing such as GCF and PTCRB. You must perform a variety of use case tests on these components to ensure that they comply with the relevant standards.