5G brings precise positioning to the Internet of Things

Cellular has ‘all the ingredients’ to enhance precise positioning indoors and for IoT

Smartphones and other small positioning devices use satellite systems like GNSS to provide positioning. However, to be most effective, GNSS requires a clear line of sight to multiple satellites, and even at its highest performance, it can only provide meter-level accuracy, which is not precise enough for industrial and indoor IoT applications. On the other hand, 5G mmWave can achieve centimeter-level accuracy in some cases, according to Kiran Mukkavilli, senior engineering director at Qualcomm.

“Cellular works really well for GNSS, and if you look at cellular deployments, they have all the ingredients in place to make this positioning work,” Mukkavilli said. “Look at our deployments. We have our macro deployments in FR1 below 7 GHz, we have our FR2 millimeter wave deployments, and we have some indoor deployments as well.”

He explained that each of these deployments has unique characteristics that aid in positioning. For example, massive MIMO deployments in the sub-7 GHz bands have large antenna arrays, which allow for accurate angular domain estimates for wide-area positioning. On the other hand, indoor deployments are typically very dense to enable high-capacity communications. Denser mmWave deployments mean more bandwidth, and more bandwidth means better positioning accuracy. However, Mukkavilli said that mmWave has both the advantages of density and large amounts of spectrum.

“From a positioning perspective, lots of bandwidth means very fine and precise temporal resolution. Small cell deployments also typically mean that we get denser nodes [...], which gives us very fine beams. So putting together the bandwidth and the fine beams that we get from these dense arrays [...], we can easily get to centimeter-level accuracy with millimeter wave,” he said, adding that millimeter wave will therefore become “a very important component” of Qualcomm’s overall positioning solutions portfolio.

However, applications involving low-power and low-complexity devices (such as IoT devices using smaller frequency bands such as 20 MHz or even 5 MHz) present positioning challenges, as precise time resolution requires a large amount of bandwidth to ensure accuracy. In short, time-based precise positioning techniques are not well suited for narrowband IoT devices.

“With small bandwidths, the temporal resolution is not as good as what we get with 100 MHz or 400 MHz, and that’s where we can exploit [...] spatial resolution,” Mukkavilli explained, offering an angle-based positioning technique called DL-AoD, or downlink angle of departure positioning, as an alternative.

DL-AoD is a device-based positioning technology where IoT devices measure the RSRP (reference signal received power) of each beam on the network and use the relative differences between them to estimate the angle of departure (AoD). These measured differences then provide horizontal angle and elevation angle information through pattern matching.

In this way, DL-AoD provides high-precision positioning for bandwidth-limited 5G IoT devices. In fact, Qualcomm demonstrated at least a 60% improvement in median accuracy within a 5 MHz bandwidth using the angle-based technique.

“Putting all of this together, what cellular can do for positioning is to complement and provide sub-meter accuracy in most places, and even centimeter-level positioning for industrial IoT and indoor precision positioning […],” Mukkavilli concluded.