T-Mobile's "5G" network will be built in 600 MHz spectrum and will only be 25-50% faster than its 4G LTE network, perhaps 400-700 megabits. Ted Rappaport of NYU Wireless, a world-class expert on 5G, emails me:

The low band (600 MHz) systems will always be limited in capacity and are not future proof no matter what special massive Mimo is used- the antennas will be too large and the bandwidths are too small, and simply can't carry the bandwidths of mmwave-- the RF channel allocations are simply too small. The wider bandwidth channels at mmwave is the only way to carry the multi Gbps data rates that will be seen in 5G. And to simultaneously also provide backhaul between cells in the same network.  

The secret sauce in millimeter wave is 400 MHz and 800 MHz channels. The 600 MHz and other low band use 20 and 40 MHz. Tmo' 600 MHz will probably be 400-700 megabits. mmWave is delivering 10gig and 20 gig in the laboratory. Verizon is getting 1 gig to each customer in their trials and can go higher. 

In 4G LTE/LAA, Tmo's 4G is delivering 500 megabits to live customers in Manhattan, pretty darn good. To do much better than that in 20 MHz 5G NR would require breaking the Laws of Physics.

The difference between 4G LTE and 5G NR is actually very small in a fair comparison: same spectrum, same antennas, same generation of equipment. The 2018 LTE goes beyond the gigabit delivering 9 ms latency. Short TTI is in the LTE Release 14 and 5G Release 15. It's most of the latency improvement and it works in 2018 models of both. 

Ted also points out the antenna problem. mmWave antennas are very small; 256 of them fit on a unit the size of a paperback novel. (We have it on film we still need to edit.) Antennas for 600 MHz are much bigger, often only two fit on a tower. When you get to 2500 & 3500, you can use 64 antenna Massive MIMO. That's why 3500 suddenly became hot. Massive MIMO is working very well and solves most of the very short reach problem.

The NY Times is reporting "implausible promises" because they are too cautious to say "lies." 



dave askJuly 2018 Verizon's $20B 5G build is starting to add customers in 2018. Gigabit LTE & Massive MIMO became real in 2017. Verizon U.S. 5G mmWave 5G is firm. Almost all the other "5G" is mid-band, 70%-90% slower + hype. Europe is mostly pr. The term 5G has been bastardized, unfortunately.

Being a reporter is a great job for a geek. I'm not an engineer but I've learned from some of the best, including the primary inventors of DSL, cable modems, MIMO, Massive MIMO, and now 5G mmWave. Since 1999, I've done my best to get closer to the truth about broadband.

Send questions and news to Dave Burstein, Editor. I always want to hear from you, especially if you catch a mistake.