Cellular has ‘all the ingredients’ for enhanced indoor and IoT precise positioning
Smartphones and other compact 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 peak performance, it still only provides meter-level precision, which is simply not precise enough for industrial and indoor IoT applications. On the other hand, 5G millimeter wave (mmWave), claims Kiran Mukkavilli, senior director of engineering at Qualcomm, can, in some cases, achieve centimeter-level precision.
“Cellular compliments GNSS really well, and if you look at cellular deployments […] they have all the ingredients to get the positioning to work,” Mukkavilli said. “In looking at the kind of deployments that we have. We have the macro deployments in FR1, sub-7 GHz and we have our FR2 millimeter wave [mmWave] deployments, and then we also have some of our indoor deployments.”
Each one of these deployments, he explained, have unique characteristics that aid in positioning. Massive MIMO deployments in the sub-7 GHz band, for instance, have large antenna arrays, which allow for precise angle domain estimation for wide-area positioning. On the other hand, indoor deployments are typically quite dense to enable high capacity communications. Denser mmWave deployment means more bandwidth, and more bandwidth means better positioning accuracy. mmWave, though, has both the benefit of density and lots of spectrum, according to Mukkavilli.
“From a positioning point of view, a lot of bandwidth means very fine and precise time resolution. Small cell deployments also typically means we get denser nodes […] which gives us very fine beams. So putting [together] the bandwidth and the fine beams that we get out of these dense arrays […] we can easily get to the centimeter-kind of accuracy with mmWave,” he said, adding that as a result, mmWave is going to be “a very important component” to Qualcomm’s overall positioning solutions portfolio.
However, because precise time resolution requires a lot of bandwidth for accuracy, applications involving low-power and low-complexity devices like IoT devices, which use smaller bands such as 20 MHz or even 5 MHz, present a positioning challenge. Put simply, time-based precise positioning techniques are not well suited for narrowband IoT devices.
“With small bandwidth, the time resolution is not as what we get with 100 MHz or 400 MHz and that’s where we can make use of […] 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 technique in which an IoT device measures each beam RSRP (Reference Signal Received Power) on a network, using the relative differences between them to estimate the angle of departure (AoD). Then, these measured differences provide horizontal angle and elevation information via pattern matching.
In this way, DL-AoD delivers high-precision positioning for 5G IoT devices with limited bandwidth. In fact, according to Qualcomm’s demo, using an angle-based technique achieved at least a 60% improvement over the median precision accuracy in the 5 MHz bandwidth.
“Put all of this together, what cellular can do for positioning is complement and deliver the less than a meter kind of accuracy most places and even centimeter level positioning […] for industrial IoT and indoor precise positioning,” summarized Mukkavilli.
For a deeper look at all of Qualcomm’s MWC22 demos, visit this resource hub.
