TDD Massive MIMO is already going wide at SoftBank Japan, yielding a 4x-10x capacity improvement on a single channel. Eric Zhao believes Massive MIMO is often the right choice where you need high capacity. Zhao finds early 32 antenna system averaging 450% more capacity in a single band. Many leading engineers agree MM is the way to go.
Worldwide, chief technologists are enthusiastic about Massive MIMO. At Huawei's MBB Forum, Hidebumi Kitahara of SoftBank confirmed the reported results, especially in crowded cells. Later in the day, Huang Yuhong of China Mobile also reported success. Her performance improvement estimates were "only" 3x, but it's early days for the technology. At SoftBank owned Sprint, Günther Ottendorfer reports a 10x improvement. Sanyogita Shamsunder of Verizon a year ago told me, "We must have massive MIMO." Nasser Al Nasser of Saudi Telecom in the release below reports a 6x improvement.