Project Fi uses Sprint Band 26, which is 800 MHz ESMR spectrum.

Why is LTE Band 26 useful?

Google’s Project Fi uses Sprint LTE Band 26 spectrum, where we used to compete head-to-head with Nextel, until Nextel bought our channels. As it was fifteen years ago, the wavelengths in the general vicinity of LTE Band 26 & 5 (850 MHz cellular) are ideal for building penetration (phone indoors). Akin to LTE bands 12,13 and 14 in the low bands (700 MHz), LTE band 26 at 806-861 MHz gives better long range coverage.

Sprint and other high/low band LTE carriers nowadays use carrier aggregation and at least LTE on the low-frequency (long-range) band as well as the high frequency band. Someday when I get a chance I would like to see how the maximum range of LTE compares to iDEN. Not just the testset lab conditions you see in the literature, but with the fading, fluttering and scintillation seen in the 40 km plus distances like I did with iDEN.

Why did Sprint shutdown Clear WiMAX?

Sprint’s 2.5GHz Band 41 WiMAX termination drivers included 10x LTE spectral efficiency. The need to pair high-frequency LTE Band 41 good for short range, high density use with band 26 good for suburban/rural is essential to modern mobile network operations. Back when I used Sprint WiMAX as an early adopter of 4G, it was frustrating to lose the 4G WiMAX signal when I walked beside my house with the tower about a kilometer away. This was not the fault of WiMAX, rather it was because of the 2.5 GHz wavelength and free space loss.

So in short the reasons to abandon Clear’s 2.5 GHz WiMAX were:

  1. short wavelength no good for standalone carrier (best blended with longer wavelength bands for less dense areas)
  2. WiMAX is not nearly as spectrally efficient as LTE.

Downside: band 26 is not available in all 2017 phones

Some high-end phones like the Blackberry KEYone GSM model BBB100-1 lack LTE band 26, yet band 26 is included in the CDMA model BBB100-3. Other top-end phones like the Google Pixel do include lots of LTE bands including band 26. As phone technology advances each year, I expect band 26 will be included in increasing numbers of phones.

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