What is latency?

Latency in LoRaWAN refers to the delay between the moment a device sends a message and the point at which it reaches and is fully processed at its destination. This delay can vary significantly depending on factors such as network infrastructure, architecture, and configuration, ranging from milliseconds in optimal conditions to minutes or even hours in challenging scenarios.

Why is it important?

Latency isn’t just about message delay; it directly affects how quickly real-world events, such as the movement of a valve, are reflected on a dashboard or Human Machine Interface (HMI). Minimizing this delay ensures that everyone has access to the most current information, allowing people and systems to respond as quickly as possible. 

Low latency is especially critical in industrial settings for:

1. Real-Time Monitoring: Many industrial systems depend on real-time data to track equipment, detect inconsistencies, or measure environmental factors like temperature, pressure, and humidity. Any delay in data can lead to inaccurate monitoring and timestamping, potentially causing missed opportunities for intervention.
2. Safety Applications: Safety-critical functions, such as emergency shower activation detection, depend on minimal latency to promptly trigger alerts and enable immediate action when needed.

Factors affecting latency and how to optimize it

1. Device Communication: One of the largest and most variable contributors to latency is the device’s ability to reach a gateway. When a device sends a data packet, it typically expects an acknowledgment packet from the gateway. Using Adaptive Data Rate (ADR) is ideal, as it allows the device to automatically adjust its data rate and transmission power based on network conditions. This helps maintain reliable connectivity to the gateway while minimizing power consumption. 
2. Gateway Placement and Configuration: Gateways form the backbone of your LoRaWAN network. Increasing the number of gateways improves device reach and connectivity, allowing devices to connect to multiple gateways and enhancing network reliability. When a device is barely within reach, it may need to retransmit messages, significantly increasing latency. To reduce this, ensure good network coverage by strategically placing gateways, ideally at a height above most equipment. Avoid long antenna extenders or low-quality materials, as they can degrade signal quality and hurt your range. 
3. LoRaWAN Network Server (LNS) Processing: The LoRaWAN Network Server is critical, as it decrypts messages and handles acknowledgment packets to devices. A fast, stable connection between the gateways and the LNS is essential. If the connection is slow, messages may not reach the LNS in time, delaying the acknowledgment and prompting devices to retransmit their messages. Ensure the server has enough resources to handle the volume of device traffic; high server load and processing delays can directly impact overall latency. In certain cases, an intermediary component may be needed to handle specific decoding and processing requirements. For instance, the Aloxy IIoT Hub or Aloxy.Core provides decoding and processing for Aloxy.Valve sensors, while maintaining low latency.

Data Lake and Visualization Layer: For many applications, the data path doesn’t end at the Network Server. Additional systems, such as data lakes or visualization tools, are often used to display or react to data events. When designing the architecture, keep latency in mind for these downstream components as well; introducing unnecessary delays here (e.g., adding 30 seconds for data processing) can significantly impact responsiveness. Each element in the chain should prioritize low latency to ensure fast reaction times.

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Written by Liam Oorts, Customer Succes Manager