In the past, carriers have been guarded if not purposely opaque about things like radio network planning, infrastructure rollouts, and other competitive details. With the smartphone boom well underway, many of those curtains are starting to fall as customers get more and more savvy with air interfaces and asking the important questions. This morning on Reddit, a T-Mobile RF engineer started an AMA, no doubt with official T-Mobile backing, to answer some LTE rollout and network modernization questions. Update: I was dropped a line and notified the AMA is being done without any official T-Mobile backing, but has been confirmed, and is nevertheless very interesting.
I obviously could not resist the temptation to ask a few questions myself, and got some interesting replies.
My questions:
T-Mobile RF engineer replies:
So there you have it. Interestingly enough, the 1 million iPhones number seems a bit low, although it's likely this is a ballpark estimate - I suspected an even larger number given the unlocked iPhone 4S sales and AT&T's post-subsidy unlock program. T-Mobile going with Remote Radio Heads (RRH) for LTE, UMTS, and GSM is also interesting - in the USA, AT&T, Sprint, and Clearwire have all gone with RRH deployments which move the power amplifiers up the mast and next to the antennas, dramatically minimizing cable losses which are generally around 2-3 dB depending on length. This leaves Verizon the sole player in the USA using the traditional power amplifier at the bottom of the tower architecture. Finally, there's official confirmation that T-Mobile will be 5 MHz FDD-LTE initially, at launch. For comparison, Verizon is 10 MHz FDD everywhere in the US, and AT&T is 10 MHz FDD or 5 MHz FDD depending on the market.
Update: The T-Mobile AMA source has dropped a few other interesting tidbits, as the AMA has progressed. Among mundane things like equipment failures, copper theft and vandalism are a major source of problems for T-Mobile in some markets, along with the usual kind of things like animal encroachment. In addition, the source uses a Samsung Galaxy S 3, and noted the use of disguised cell sites.
Source: Reddit