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T-Mobile’s deployment of commercial hardware from Nokia and Intel into a real-world environment is a critical step in deploying nation-wide mobile 5G network, which the carrier has said it would accomplish by 2020.
The deployment is intended to test how millimeter wave radio signals operating at 28 GHz will behave in an urban setting, how they will interact with LTE systems and how they can be integrated with existing networks.
T-Mobile’s 5G plans center on creating a high-speed, low-latency mobile network, but to do that, the 5G international standards need to be finalized, and that’s not expected before 2020. Among other goals, the T-Mobile 5G test is intended to help drive the development of standards and provide a basis for hardware and chipset design.
T-Mobile announced its 5G deployment on Jan. 3, the same day that Verizon announced that it had selected Samsung as the builder for some of its 5G network equipment, primarily home routers. Verizon is focusing its 5G development on fixed wireless hotspots that could be used in both urban and rural settings.
AT&T, meanwhile, has been deploying a form of high-speed mobile networking that it has been calling its High Speed Evolution 5G, but what AT&T has actually developed is high-speed LTE. The difference is that the 5G standards will specify OFDM (orthogonal frequency division multiplexing) which has much lower latency and the potential for higher speeds than LTE.
Sprint, meanwhile, has announced plans to field a 5G network by the end of 2019, but has provided few details. However, that carrier has conducted tests of 5G networking in its 2.5 GHz spectrum.
T-Mobile’s announcement goes hand-in-hand with an announcement that T-Mobile has exceeded the goals of its LTE expansion plans. In an end-of-year blog post, CEO John Legere has said that the company has already achieved gigabit speeds on its LTE network (which is what AT&T is claiming for its “5G” service) and that the carrier is already deploying 5G ready equipment.
Unlike the other carriers which are focusing on millimeter wave technologies for their 5G plans, T-Mobile is working on a plan that includes low, mid-range and millimeter wave technologies. T-Mobile is planning to use its newly acquired 600 MHz band, which it won in the FCC spectrum auction last spring, to deploy much of its mobile capability.
This is because 600 MHz radio signals have a distinct advantage in long distance coverage and in building penetration. The carrier has announced that it will begin selling wireless devices including phones that work on its 600 MHz frequencies in 2018.
T-Mobile also plans to deploy 5G in its mid-range bands around 2 GHz as well as in the millimeter wave frequencies around 28 GHz, which is where the test deployment is operating.
Because of the way OFDM works by sending one data stream divided among many frequencies, it gains some advantages that single frequency millimeter wave communications lacks, including better building penetration.
Because the same stream is divided among many frequencies, OFDM can transmit each portion at a relatively lower speed, and use computing power to accurately combine the data on each of the frequencies into a single high-speed stream.
What this means is that 5G networks, however they’re deployed, have the potential to connect everything. Verizon’s plan would create on-premises hot-spots that devices could connect to in much the same way that cable WiFi works today. With T-Mobile you might be able to skip the hot-spots, but you wouldn’t have to. A mobile 5G solution can also work with hot-spots.
Ultimately, however, both types of 5G, mobile and fixed wireless, are going to be required in a 5G world. In addition, there’s no reason to expect LTE to vanish in the near future.
So what you’re going to see is a communications landscape that includes fixed wireless that will be well-suited for commercial communications, especially some types of IoT implementations where the higher powered radios necessary to reach a cell tower, even one that’s fairly close, aren’t feasible.
But the limitations of millimeter wave transmissions in buildings and in urban areas where wall penetration and reflections are going to cause problems mean that cells will necessarily be quite small and that transmitter power won’t be as critical as it might be otherwise, so hot-spots are a viable solution.
On the other hand, there will be a growing need for 5G networks to be mobile as people with cell phones and devices with 5G capabilities move about in the environment, switching from cell to cell as they move. There, a mobile approach will be necessary.
The same is true for remote IoT devices that need to communicate directly with the network because there won’t be any hot-spots nearby. Such devices will include everything from environmental sensors to vehicle tracking–especially of autonomous vehicles. In fact, the extremely short latency provided by 5G will be critical for those self-driving cars that will need to communicate with each other instantly.
Of the two approaches, T-Mobile’s efforts to deploy a mobile 5G network seem to be heading more in the right direction. A mobile device doesn’t have to move, whereas a fixed wireless approach is just that–fixed. To be competitive, Verizon will have to develop a mobile solution as well. T-Mobile already has that.