With Dynamic Spectrum Sharing (DSS), Deutsche Telekom is testing a new process to bring 5G to the surface with less bandwidth and speed. Existing cellular antennas from 3G times are used for the parallel operation of LTE and 5G. The old 3G is not (yet) completely switched off.
So far, Deutsche Telekom has not made any official announcements on the subject of DSS, but the technology is already being used, as Tobias Dirking discovered on the basis of an appropriately converted mobile phone location in Wittlich, Rhineland-Palatinate. On his YouTube channel, Dirking goes into the special features of the cell phone location and explains the local implementation of DSS.
Accordingly, Deutsche Telekom in Wittlich is offering the new mobile radio standard on the 5G band n1, which is operated at 2,100 MHz and thus a UMTS frequency (B1), which other providers such as O2 and Vodafone are already using for LTE. This is now also being done by Deutsche Telekom in Wittlich, but in parallel operation with 5G via DSS, which can transmit LTE and 5G with existing antennas after a software upgrade.
Although Deutsche Telekom only has a 10 MHz spectrum (20 MHz from 2021) at 2,100 MHz, the Wittlich site is operated at 15 MHz for LTE and 5G via DSS. UMTS is still active in Wittlich, however, but reduced to a carrier with only 5 MHz instead of 10 MHz, which also overlaps with the LTE / 5G block at 2.5 MHz, so that not a total of 20 MHz, but 17, 5 MHz can be used. It was not possible to determine on site whether this would lead to interference, but speeds of 11 to 13 Mbit / s could still be achieved via 3G and 3G telephony had also been carried out without interference.
The n1 cannot approach the gigabit speed of 5G in the 3,600 MHz range over the n78 band, but at 2,100 MHz the range of the signal increases from less than 1 km to over 2.3 km at speeds of 62 Mbit / s in the downlink and almost 47 Mbit / s in the uplink. The LTE anchor on band 20 required for 5G non-standalone (NSA), which is also used in Wittlich, only managed a maximum of 20 Mbit / s in the downlink, rather 10 to 15 Mbit / s, explained Dirking.
Dirking suspects that the mobile radio standard in Wittlich is an initial field test and that Deutsche Telekom will not initially completely switch off its UMTS network, however, as in Wittlich, will reduce it to a 5 MHz carrier so that LTE and 5G with DSS can be brought into the area, but devices without LTE are still supported. Users without a 5G smartphone will get better LTE coverage, users with 5G smartphones will have extended 5G coverage, and users of a contract without 5G or LTE can continue to use the 3G network.
Source: https://www.computerbase.de/2020-04/deutsche-telekom-5g-dynamic-spectrum-sharing-dss/