Questions I would ask AT&T October 1, 2015 11:04
What percentage of your sites are you converting to RRH (remote radio head) technology?
RRH technology takes radios that typically have been at ground level and places them on the towers behind the antennas. The RRH technology is useful in providing better coverage for the higher frequency spectrum. For AT&T, RRH technology would help mitigate the coverage differential between 700MHz and PCS, 700MHz and AWS, and 700MHz and WCS. If low band coverage (700MHz) were represented by a quarter, and mid band coverage (PCS) by a dime; moving the PCS channel to RRH technology would make the PCS coverage grow to the size of a nickel. This would allow AT&T to have similar capacity across a larger amount of their coverage.
Are you using RRH technology only for your high band spectrum or all spectrum except low band?
Applying RRH technology to low band spectrum in rural areas would fill in coverage holes but increasing coverage in urban areas with RRH technology would increase interference.
What percentage of your customers have a device that will operate on 700 MHz (band 17), AWS (band 4), and WCS (band 30)?
The iPhone 6s has an available version that supports the WCS band, but since not all of AT&T’s customers have a phone that supports their entire LTE spectrum, network coverage and capacity enhancements will not be experienced by the entire user base.
How much back haul capacity do you provide to each cell site for each 10 MHz of LTE spectrum?
To prevent back haul from being a bottleneck, 225 Mbps should be provided for each 10 MHz of spectrum (75Mbps per sector).
What is your average monthly back haul cost per cell site ($/Mbps)?
Site back haul costs would surprise many in the analyst community. When sites only supported voice calls, site leases (land and tower) dominated the operations expense. With the move to data, the site lease (average $1500/mo) is dominated by the back haul lease ($8000/mo). This becomes more painful as you consider the need for doubling data capacity which could then double your site back haul expense.