1&1's 5G network: On the road in Germany's first Open RAN

With its network from 1&1, there will be a fourth mobile operator in Germany after Deutsche Telekom, Vodafone, and Telefonica. Or rather, there will be, because the 1&1 network is still at the very beginning. We tried it out.

First, the most important technical aspect: 1&1 is building its mobile network differently from existing networks. It is a so-called Open RAN. Open RAN is a new approach to building 4G and 5G mobile networks with standardized components and thus independently of the provider. The abbreviation RAN stands for “Radio Access Network,” i.e., the complete technology of the mobile network, from the backbone connection to the radio heads, i.e., the base stations.

Unlike proprietary networks, which were delivered as a black box from a single source, an Open RAN can be broken down into many standardized components that communicate with each other via standardized, i.e., open and interoperable interfaces. This allows the components to come from different manufacturers. The modular structure makes it possible to virtualize many components, for example, to provide them as a cloud service instead of on local servers, and to embed third-party apps at all network levels.

In addition to a wider selection of components, the advantages of Open RAN include speed in development. The complete network control takes place purely software-based on standard servers. 1&1 does not have to carry along existing infrastructure that has grown over decades with competitors from 2G to 3G and 4G, but is building a 4G and 5G network completely from scratch. 1&1 even defended the designation “the most modern network in Europe” successfully in court; the lawsuit was filed by Telekom.

Over 500 data centers are needed

With only three 5G frequency bands, currently at 2600 and 3500 MHz, the 1&1 network is not overly complex. According to the Federal Network Agency's specifications, 1&1 must have completed a quarter of the expansion by 2025 and half by 2030. That would be 12,600 locations with three antennas each in 390 larger and smaller cities. In addition, there are over 500 regional data centers, 24 edge data centers, and four so-called core data centers. These are connected to each other via fiber optics. The technology at the antenna locations themselves is less complex than in a conventional network.

For the construction of the network, 1&1 has teamed up with the Japanese Rakuten Group, which operates the only other commercial Open RAN network to date. Rakuten acts as a general contractor, bundling the other participating companies—around 80 partners are mentioned. However, as 1&1 assures in the conversation, all contracts are structured in such a way that the company from Montabaur can also work directly with suppliers and partners should problems arise between Rakuten and other providers in some constellations. 1&1 intends to forgo components from Chinese manufacturers in its entire own network.

If you are transmitting in the 5G network with a 1&1 SIM card, you are currently doing so via national roaming over Telefónica. Currently, there are about 1000 own 1&1 antennas live across Germany, distributed across numerous cities and towns. At the time of testing, there were only three in Berlin. 1&1 does not make the exact locations public, but suffice it to say: they are not in the city center or near tourist hotspots, but in peripheral areas with low residential density. It is currently extremely unlikely that 1&1 customers in Berlin will randomly transmit and receive in an Open RAN cell of 1&1, especially since the reception indicator on the smartphone does not provide information about whether the smartphone is registered via national roaming or not.

Faster in Roaming

As a sample, we performed several speed tests in the Berlin 1&1 cells with two SIM cards. An Apple iPhone 13 Pro with a Qualcomm X60 modem and a Nothing Phone (2a) with a Mediatek radio unit were used. With the iPhone, we were able to achieve download speeds between 111 and 341 Mbps, and upload speeds ranged between 30.7 and 54 Mbps. This resulted in average values of 244 and 40.44 Mbps, respectively. The Nothing Phone (2a) showed less strong fluctuations and transferred data back and forth with 293 to 325 Mbps in download and 44.8 to 53.9 Mbps in upload. The average measured values, at 306 Mbps downstream and 47.51 Mbps upstream, were significantly higher than those we achieved with the iPhone.

Quite stable speeds, therefore, but significantly less than what is possible with a 1&1 SIM in Telefónica's partner network. Our measurements via national roaming went far beyond that in terms of download rates. With both smartphones, we repeatedly achieved well over 500 Mbps, with comparable upload rates. Across all measurements, the Nothing Phone (2a) with the Mediatek modem again delivered the more consistent and higher transmission speeds: 397 vs. 380 Mbps in down and 49.4 vs. 40.2 Mbps in upstream. However, unlike in the 1&1 cells, there were isolated cases of noticeably slow measurements between 10 and 30 Mbps down and under 5 Mbps up during roaming operation. However, one minute later, the measurements were back to the usual level.

In national roaming, 1&1 is currently working on the switch from Telefónica to Vodafone. Of all providers, Vodafone, one might say, because there were disagreements with the provider regarding the construction of its network. Radio mast operator Vantage Towers, closely associated with Vodafone, had massively undershot expansion requirements for 1&1, while simultaneously bringing numerous Vodafone locations online. The dispute went all the way to the Federal Cartel Office—outcome open.

(sht)