Deutsche Telekom has flown a High Altitude Platform (HAP) project out of stealth mode, revealing both successful trials and ambitious plans to develop a new aircraft that pushes the boundaries of High Altitude Platforms (HAPs) for cellular coverage.
DT took the wraps off a project that it has been working on over the past five years, announcing that it had successfully provided coverage to mobile devices on the ground from an aircraft flying at 14km.
The demo, of a remotely-piloted aircraft, was the first that integrated a HAP with a commercial terrestrial network. It used a 10MHz channel in DT’s 2.1MHz LTE band, creating a cell range of 10km from an altitude of 45,000 feet. The aircraft was able to interwork with the commercial phone network on the ground, with drive test users handing over from terrestrial cells to cells provided by the aircraft. The tests delivered DL throughput of 70Mbps and added only a ms to the observed terrestrial latency.
Although DT was delighted with the tests, it is its future development for the platform that it is really excited about. CEO Timothy Hotges was on hand to hail the work as an example of European innovation, and of DT’s own innovation via its TIP investment pot.
The trials were part of a joint project between DT and SPL, a UK-based company formed in 2014 that DT has been investing in since 2016.
Richard Deakin, Managing Director of DT’s partner company SPL, said that the company is developing a platform that could stay in the air for nine days, carry a 140km payload, and provide service day and night.
The new aircraft would be powered by liquid hydrogen fuel cell. That means it can operate day and night, unlike solar, and also provide more power for flight and for the on-board base station. The aircraft is designed to carry and provide power to a massive 3m by 3m antenna, with 2048 phased antenna elements, providing beam-formed coverage of 200 “cells” over a ground area diameter of 140km.
Deakin said the plan is to have a factory production of 200 of the new aircraft a year. The first flights of the new platform are expected in 2022.
DT said it is working on both sub 6GHz and mmWave antenna versions, and sees applications for direct indoor coverage at lower bands, and also for a fixed broadband alternative by connecting to a FWA CPE.
With a single aircraft creating hundreds of cells, DT said that it could theoretically cover all of Germany with 30 aircraft, Kenya with 50 and all of the USA with 670.
As it can fly to an automated pattern or be remotely controlled, it can also provide more accurate coverage than stratospheric balloons, according to DT CEO Timothy Hotges. Where coverage overlaps and cells are in the same frequency, the coordination techniques will be necessary, and DT is also working on that aspect, the company said.