Evaluating Sub Gigahertz Spreading Factors against Cellular Coverage Enhancement Energy Costs
Sub-GHz LoRaWAN spreading factors consume less baseline battery energy than NB-IoT coverage enhancement repetitions in deep indoor deployments.
Energy per Delivered Message
Meaning
Efficiency metrics quantify the total electrical power consumed to successfully transmit and acknowledge a discrete packet of data across a wireless link. Measuring energy per delivered message allows for the comparison of different radio protocols and hardware configurations regardless of their peak power consumption. This metric accounts for both the active transmission time and the overhead of network synchronization.
Consumption Rate
Small sensors often prioritize this value over raw speed to maximize battery life. A low energy per delivered message indicates that the device spends very little power on retransmissions or idle listening. Optimizing the sleep cycle of the radio module is the most effective way to reduce this figure.
Protocol Overhead
The size of the header and the complexity of the handshake influence the final result.
Battery Longevity
Designing for a specific energy per delivered message helps engineers predict the operational lifespan of a remote device. If the cost of sending one kilobyte of data is known, the total capacity of the cell can be divided by this value to estimate the total number of reports the device will provide. This calculation is essential for qualifying hardware that must operate for years without human intervention.