There are always some test results one cannot readily explain. And that often happens when testers do not have the ability to create full "apples to apples" comparisons. Consider comparisons of 4G and 5G speeds.
5G is supposed to be faster than 4G. Higher-frequency channels should deliver faster speeds than lower-frequency channels.
Also, in principle, spectral efficiency should be higher when channels are wider or larger, at least in part because less bandwidth is “wasted” on guard bands. Larger channels, with fewer guard bands, should produce higher efficiency.
That might be the case for a test of 2.6-GHz 5G spectrum on Sprint’s network in Chicago, which found 2.6-GHz spectral efficiency greater than on millimeter wave spectrum.
“Based on RB-normalized throughput and MCS allocations, the Band 41 spectral efficiency was at least 50% higher than 5G millimeter wave for most test scenarios in Chicago when compared with testing did in New York City late this summer,” according to a study of Sprint’s network.
But there are notable elements of the test that likely account for the finding that 2.6-GHz efficiency was higher than that of millimeter wave networks. The Chicago test used some form of carrier aggregation, where both the 2.6-GHz 5G channels and also 4G LTE bandwidth could be used by the phones tested.
In principle, that means the effective 5G bandwidth theoretically could use 120 MHz of spectrum across the 4G and 5G networks. It seems likely that the millimeter tests used channels of less than 120 MHz, since 5G channels can range from 5 MHz up to 100 MHz,
Of course, radio technology also matters, as is the case with different flavors of MIMO (multiple-input, multiple output) radios. It also seems very likely that the Chicago tests used commercially-available phones, while the millimeter wave tests used modems, not phones. Those test elements might have affected results.
But the key explanation most likely includes channel width as the explanation.
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