Telstra "delivered 5X data growth at fixed cost by FY21." That required productivity improvement of 37%/year. Verizon estimates 40%/year. CEO Vestberg puts it another way: "Our cost per bit is 1/10th of what it was." Deutsche Telekom estimates 1/8th. None of these figures are exact, but the trend is obvious.

Wireless technology is improving at a ferocious rate. As we all know, demand for bits continually increases. The improvements in technology have generally matched the growth in traffic demand. Now that traffic growth is slowing, overcapacity is likely. 

The rough equivalence between capacity and demand is confirmed by the financial reports of Telstra, Verizon, and most other telcos. Capital spending has been flat while generally meeting demand. Speeds have gone up dramatically.

Supply and demand explain much of what's happening in telco networks. 

 The demand for more data has been strong since the iPhone changed everything. For the first few years, traffic grew as much as 100%/year as people upgraded their phones. Once most people had smartphones, the growth rate dropped. In the US, it's now down to 30-40%; some carriers in 2018 were below 30%.

The network improvements took off around 2015. Carrier aggregation suddenly turned "junk spectrum" to production. 2x2 MIMO (multiple antennas) became common. Soon, 256 QAM coding raised capacity by as much as a third. MIMO climbed to 4x4. 

Massive MIMO was introduced in China and Japan in 2016. By using 64 antennas or more, capacity roughly tripled on average. Since Nokia, Ericsson, and Samsung caught up with Massive MIMO equipment in 2019, it is being widely used. Huawei has shipped 600,000 Massive MIMO radios and virtually all but low-band 5G radios are MM.

Without raising capex, telcos are able to deliver in 2020 10-25 times as much capacity as in 2016. NTT, Orange, and AT&T are seeing the cost of capacity falling so rapidly they are cutting capex. (Contrary to rumor, 5G is generally less expensive than 4G or about the same cost.)

Telcos now have a good problem: How to fill networks.