Not All Sub-1 GHz Spectrum Equal, AT&T Tells FCC

Not all sub-1 GHz spectrum is equal or superior to spectrum in higher bands, AT&T said in a filing posted by the FCC, answering Wireless Bureau questions on AT&T’s proposed buy of spectrum from Club 42 CM Limited Partnership. Much of the response was redacted. But AT&T did not redact details it offered on the difference between sub-1 GHz spectrum bands. AT&T argued that the lower 700 MHz D and E blocks have limitations that mean they shouldn’t be counted with other low-band spectrum as the FCC does a competitive analysis. “These blocks currently can only be used in conjunction with spectrum above 1 GHz, rendering moot many of the ‘inherent benefits’ of spectrum below 1 GHz,” AT&T said. The blocks are also subject to “unique technical limitations,” the carrier said. Pairing the lower 700 MHz B or C blocks with the lower 700 MHz D or E blocks “would create an unacceptable level of self-interference within a device supporting both blocks,” AT&T said. “Such self-interference occurs because these blocks are directly adjacent, and there is not enough frequency separation to mitigate interference.” AT&T has to do substantial work on its towers just to “combat this interference and, in a significant number of cases, even that is ineffective and power must be substantially reduced -- by approximately 6-9 dB -- to limit the impact on B Block operations,” AT&T said. The filing was made in docket 14-145.