Neville Ray's central justification for the merger is that in 5G  "mid-band spectrum will achieve a 52 percent improvement" over 4G. That is not an appropriate figure today.

One reason for the improvement was that 5G allows 100 MHz bands compared to the 20 MHz bands of 4G. Sprint and China Mobile both have blocks of over 100 MHz at 2.6 GHz. The new 4G SuperBAND from Huawei effectively coordinates 100 Mhz of spectrum for a similar result. T-Mobile's vendors, Nokia and Ericsson, should soon be able to do similar.

Ray in a footnote points out he doesn't know whether his claim is accurate. "The spectral efficiency improvements are derived from equipment vendor simulations, internal T-Mobile analysis, and ITU requirements." Those equipment vendors are trying to sell him 5G equipment and have the incentive to make inflated claims. They are not a reliable source. It's easy to imagine testing that produces a preferred result.

There was no test data available when Ray (a first-rate engineer) wrote in June 2018. Fortunately, several vendors can now provide the equipment to provide more accurate figures. I have data from T-Mobile's parent company, Deutsche Telekom, that 5G speeds in 100 MHz of mid-band spectrum are 350-850 megabits. That's slower than the 4G starting to be deployed. 

SuperBAND 4G performance undermines the primary engineering argument for the deal. The early results from 5G suggest the actual testing of 5G will show less benefit than the T-Mobile claim. 

T-Mobile in Manhattan independently tests at 500 megabits down using LTE LAA. This is much faster than Ray's expectation for 5G because of the use of unlicensed spectrum through LAA. That's rapidly deploying across the country.

The FCC should suspend analyzing the deal until T-Mobile supplies current data. I'd expect the actual improvement in sub-6 GHz  is less than the annual 40% improvement Verizon reports for the last several years.

p.s. The filing makes claims about the capabilities of the Sprint network that are no longer true. Sprint cut capex in 2017 to under US$3 billion, leaving them far behind. They are raising capex to US$5-6 billion in 2018 and 2019. The performance already has dramatically improved.

Ray's analysis does not include the use of the 3.5 GHz shared CBRS spectrum, which is going live in the next few months. T-Mobile has demonstrated good results in CBRS. Commissioner Mike O'Reilly is confident hundreds of MHz in 3-7-4.2 GHz will also become available. I believe that spectrum could achieve most of the performance benefits of the merger.