Despite their excellent range, power and cost, not all Low Power Wide Area Networks (LPWANs) are created equal. You should consider many criteria when selecting an LPWAN technology.
By Ho Nguyen -May 1, 2019
Low Power Wide Area Networks (LPWANs) are the fastest growing IoT communication technology and are a key driver for global IoT connections. With various LPWAN solutions and vendors available today, choosing the right technology for your IoT projects is no easy task. To help you select the right solution for your specific use case and application, here are the top 10 criteria you should consider.
The importance of industry-grade reliability, especially in mission-critical applications, cannot be overstated. High reception rate and minimal packet loss eliminate the need to resend messages, even in unfavorable conditions. This ensures important data arrives quickly while reducing power consumption due to multiplicated transmissions. For LPWAN technologies operating in the increasingly congested, license-free spectrum, interference resilience is a prerequisite to ensure high reliability. An LPWAN’s technical design determines its ability to avoid interference or packet collisions when the traffic is high, which improves the overall reception rate. A robust technology combines a number of versatile approaches like narrow bandwidth usage, short on-air radio time, frequency hopping techniques and forward error correction to minimize contention likelihood.
Message confidentiality, authentication and integrity are core elements of network security. Multi-layer, end-to-end encryption should be natively embedded in the network to protect message confidentiality against eavesdropping and potential breaches. Advanced Encryption Standard (AES) is a lightweight, powerful cryptographic algorithm for data encryption in IoT networks. Typically, 128-bit AES can be used to establish network-level security for data communications over the air interface from end nodes to the base station.
At the same time, Transport Layer Security (TLS) protocol for backhaul connection provides a complementary security layer to protect IP-based data transfer to the cloud. The most secure LPWAN technologies also incorporate rigorous message authentication mechanisms to confirm message authenticity and integrity. This ensures only valid devices can communicate over your network and messages aren’t tampered or altered during transmission.
3. Network Capacity
A large network capacity allows you to scale with your growing demand in data acquisition points without compromising Quality-of-Service. As the radio range is almost identical across LPWAN technologies, network capacity becomes an important indicator of infrastructure footprint. The more end devices and daily messages a single base station can support, the less infrastructure you’ll need. Efficient use of the limited radio spectrum, or spectrum efficiency, is important in achieving a large network capacity. An ultra-narrowband approach with minimal bandwidth usage provides a very high spectrum efficiency, allowing more messages to fit into an assigned frequency band without overlapping each other. Simultaneously, LPWAN systems employing asynchronous communication need a mitigation scheme to prevent packet collisions (i.e.self-interference) as the number of messages and transmission frequency increase.
4. Battery Life
Battery life has a major impact on your Total-Cost-of-Ownership and corporate sustainability goals. Though LPWAN technologies share some common approaches to reduce power consumption, battery life still greatly varies across systems. This is attributed to the significant difference in on-air radio time—or the actual transmission time of a message, which is especially important given that transmission is the most power-intensive activity. In cellular-based LPWANs, synchronous communications with heavy overheads and handshaking requirements also quickly drain power.Despite their excellent range, power and cost, not all Low Power Wide Area Networks (LPWANs) are created equal. You should consider these criteria when selecting an LPWAN technology.
5. Mobility Support
Moving devices, moving base stations or moving obstacles along the propagation path are all sources of Doppler shifts and deep fading that lead to packet errors. LPWAN technologies that lack resistance against Doppler effects can only support data communications from stationary or slow-moving end devices. This limits their applicability in specific IoT use cases such as fleet management. Similarly, these networks may fail to connect nodes operating in fast-changing environments such as a device installed next to a highway with vehicles traveling more than 100 km/hr.
6. Public vs Private Network
When selecting an LPWAN solution, you also need to consider which one suits your requirements better—a public or a private network. The biggest advantage of public LPWANs run by network operators is infrastructure cost savings. However, public LPWANs mean you’ll be dependent on the provider’s network footprint which is often far from global ubiquity. Public LPWANs leave coverage gaps in many areas and nodes operating at the network edge often suffer from unreliable connections. Private networks, on the other hand, allow for rapid deployments by end users with flexibility in network design and coverage based on their own needs. Another major drawback of public networks is data privacy concern over the centralized back-end and cloud server.
7. Proprietary vs. Standard
By supporting multiple hardware vendors, industry-standard LPWAN technologies with a software-defined approach help avoid the problem of vendor lock-in while promoting long-term interoperability. Adopters, therefore, have the flexibility to adapt to future technological trends and changing corporate needs. Passing a rigorous evaluation process, solutions standardized and recognized by a Standards Development Organization also deliver guaranteed credibility and Quality-of-Service.
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8. Operating Frequency
Operating frequency is another element to consider when choosing an LPWAN technology, as it can considerably influence network performance. Due to the high-cost barrier of licensed bands, most LPWAN vendors leverage license-free industrial, scientific and medical (ISM) frequency bands for faster technology development and deployment. While there are many ISM bands available today, there are some major differences between 2.4 GHz band and sub-GHz bands. Typically, LPWAN operating at 2.4 GHz provides higher data throughput at the expense of shorter range and battery life. On top of that, 2.4 GHz radio waves have weaker building penetration and are exposed to much higher co-channel interference.
9. Data Rates
Each IoT application has a different data rate requirement which should be measured against the LPWAN solutions under consideration. It’s worth noting that most IoT remote monitoring applications are rather latency tolerant and only need to transmit data periodically. As faster data rates often come with trade-offs in range and power consumption, opting for the solution that best balance these criteria will benefit your Return-on-Investment (ROI).
10. Variable Payload Size
Payload or user data size should be driven by actual application needs rather than fixed by a certain technology. LPWAN solutions with variable payload size allow users to seamlessly integrate new use cases into their existing network infrastructure—regardless of the payload requirement.
To sum up, the technology and technical design behind an LPWAN solution determine its performance in the criteria discussed above. Selecting the right solution requires weighing these criteria according to your IoT application requirements and measure different LPWAN options based on the defined criteria.