PNT Roundup: Positioning integral to system design of 5G cellular networks

The cellular 5G standard targets latencies under 1 millisecond, data rates of up to 10 gigabits per second, extremely high network reliability and better accuracy in positioning. With location awareness becoming an essential feature in many new markets, positioning is considered as an integral part of the system design of upcoming 5G mobile networks.

The cellular industry is currently implementing Long-Term Evolution (LTE)-Advanced, which might be called “4G” mobile broadband. Simultaneously, the industry is preparing the next step, a fifth-generation (5G) system. It will process communication 10 times faster than 4G, according to experts. 5G rollout will be complete in many international metropolitan areas by 2020.

Positioning Performance for 5G NR and other technologies in different environments. (Image: Fraunhofer IIS)

Adaptive array antennas

In addition to the precise positioning it will afford, 5G shares another characteristic with GPS/GNSS: adaptive array antennas for digital beamforming (DBF). Adaptive arrays have many advantages for PNT, primarily in mitigation for multipath, jamming and spoofing.

Adaptive antenna arrays with DBF are becoming increasingly important for PNT in challenging signal environments. DBF combines multiple antenna inputs to generate gain in arrival direction of the desired satellite signal and to create spatial nulls in the direction of jamming. (See the January 2017 Innovation column “Correlator beamforming for low-cost multipath mitigation” and the February follow-up, “Mitigating interference with a dual-polarized antenna array in a real environment.”)

Picocells

Emerging applications of DBF in 5G involve dense networks of picocells, small cellular base stations that typically cover a small indoor area. Picocells extend coverage where outdoor signals do not reach well, and add network capacity in areas with very dense phone usage. 5G architectures will use adaptive array technology to achieve high data rates, spectrum reuse and communications robustness.

The implications for PNT are that 5G will require improved (relative) PNT to operate effectively, and picocells will be a source of PNT information in constrained environments.

5G involves massive directional communications via multiple-input, multiple-output (MIMO), enabling high-bandwidth communications in fading (multipath) channels by using multiple antenna inputs to adapt to channels. It can do this without knowledge of user location, but it adds to the processing complexity. The directional capability can enable multiple users to be serviced in a picocell at different frequencies, while permitting spectrum re-use by nearby picocells through narrow beamwidth and the limited range of millimeter-wave (mmWave) frequencies.

The PNT implications of 5G architectures, according to Gary McGraw of Rockwell Collins, are that 5G picocells will be synergistic with PNT in challenged environments — naturally, indoor and dense urban. They will necessitate development of distributed, networked PNT processing and infrastructure.

Fraunhofer

The 5G positioning framework will integrate a multitude of sensors into a hybrid positioning scheme, according to the Fraunhofer Institute for Integrated Circuits (IIS) in Germany. Fraunhofer IIS is currently prototyping low-latency and high-precision positioning systems for legacy LTE and future 5G New Radio (5G NR).

5G NR enables positioning by providing high bandwidths for precise timing, new frequency bands at mmWave, massive MIMO for accurate angle-of-arrival estimation and new architectural options that support positioning. Improved accuracy, robustness and latency can be achieved, according to the institute.
5G provides fast and reliable access to moving objects to achieve time-critical process control and optimization in industrial environments. Increased contextual awareness of goods, parts, machines and workers will enable new interaction and collaboration, the institute said.