Essential one-way latency contribution factors

Test consideration for low latency communication

Make the right design decision and ensure best in class implementation of the latency critical components.

The one-way end-to-end communication latency is a critical performance parameter for the majority of IoT applications. The typical requirements range from minutes for environmental sensors or smart meters to less than 100 ms for voice communication or to less of one millisecond in factory automation. There are several factors influencing the end-to-end latency such as scheduling schemes, link transmission speed or distance. Considering all relevant aspects of the end-to-end packet flow should result in selecting the appropriate architecture, technologies and features to meet the application requirements. Finally, the latency on the wireless communication interface is dependent on the best-in-class RF performance.

Testing low latency designs

For the design of low latency devices and network elements, it is essential to understand the different sources of delay and the influence of changes in configurations. There are various possibilities to measure the latency for this purpose. It could be the good old PING, which just gives a rough estimation of the two way latency or using IETF standards defined originally for service level agreement verification. An example for this is two-way active measurement protocol (RFC 5357), which allows also accurate one-way measurements in case of time synchronized endpoints.

Best-in-class RF performance

The RF performance of a wireless device is one of the key elements for the low latency design. For example, in difficult RF conditions, the packets need to be repeated and there is a need to switch to a more stable modulation scheme. This results in lower communication speed or the use of technologies applying coverage enhancements procedures. Therefore, having an eye on the RF and antenna performance and testing the overall RF performance including receiver sensitivity is of utmost importance.