Ask the Quexperts: How to choose between 5G mmWave and sub-6GHz for IoT

Dominikus Hierl
Senior Vice President Sales, EMEA, Quectel Wireless Solutions
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5G mmWave has introduced a new era of high-speed connectivity. Qualcomm, for example, has demonstrated that connectivity speeds on commercial devices can be 16 times faster than 5G operating only in sub-6GHz frequencies. The headline here is that in theory, 5G mmWave is the obvious enabler of a wide range of IoT use cases and applications.

Away from the theory, this isn’t necessarily the case. While 5G mmWave certainly delivers ultra-fast data speeds of 5Gbps and offers greater capacity and the capability to transmit more data in densely populated areas, it is not deployed everywhere. In addition, there are cost implications to rolling out the dense infrastructure that 5G mmWave requires.

The nature of 5G mmWave means that cell sites must be located close to connected devices, as the technology can suffer from transmission loss and signal range is relatively short. In addition factors such as weather, terrain and buildings can negatively impact performance. Higher frequencies can be impeded by rain and other atmospheric conditions while trees, foliage and construction materials such as concrete, steel and energy efficient glass can block signals. In urban settings, mmWave signals can be limited to travelling as far as a single city block.

Application requirements can determine the choice between 5G mmWave and sub-6GHz for IoT

However, for IoT use cases that demand high speed, are deployed in densely populated areas and can support a business case that can pay for 5G and 5G mmWave in particular, the technology has significant attractions. It is one of the few means to ensure devices have access to the low latency, high-capacity networks they need to perform effectively. Sensitive, mission-critical apps such as those in healthcare, assisted driving or public safety certainly need the capacity. In addition, it is ideal in high-traffic environments such as sports stadiums and other large venues where it can support large numbers of connections.

5G mmWave can deliver on many of the requirements of IoT applications but it is not the optimum option in every case and a blend of different approaches to wireless connectivity is needed to ensure IoT performance.

In contrast, sub-6GHz 5G works well in lower traffic, rural areas where devices are not necessarily near to cell towers. The nature of the technology means that sub-6 frequencies travel further and are affected by fewer obstacles, making them well suited for wide area coverage and IoT use cases such as smart cities and healthcare.

Sub-6 frequencies are commonly in the 3.3 to 4.2GHz range and offer transmission speeds of between 50Mbps and 200Mbps. Network latency is between 20-10 milliseconds and bandwidth is approximately 500Mbps. This is clearly far lower performance than that offered by mmWave 5G but sub-6 is far more widely deployed, partly because it can utilize the existing infrastructure of LTE networks.

Sub-6 therefore offers better range and coverage than mmWave 5G and for many IoT applications, this will be a compelling advantage. For data-intensive IoT applications that, for example, involve video streaming, the higher bandwidth and lower latency could prove to be a compelling reason to utilize mmWave 5G. The bandwidth requirements of your use case, the locations in which devices will be deployed and the sensitivity to latency of the service will be the determining factors that make the choice between sub-6 and 5G mmWave for IoT.