OpenSignal has released the next installment of its State of LTE report, which tracks the coverage, speed and overall performance of 4G networks worldwide. The report includes data on 183 operators globally drawn from our crowdsourced network of smartphone users in the three months between June and August.

According to the report, there are surprisingly fast networks emerging in Eastern Europe as operators launch powerful LTE networks over multiple frequency bands. East Asia is starting to show off new LTE-Advanced networks and expand 4G coverage far and wide. In South Korea you can now expect to get an LTE signal 97 percent of time, making 4G nearly as ubiquitous as 2G and 3G.

But some of LTE earliest movers fall behind the curve. The U.S., Sweden and Japan were among the first countries to launch LTE,and consequently they have some of the highest coverage networks in the world. All three, however, are losing ground in terms of speed. The U.S. may have one of the highest concentration of LTE devices in the world, but its 4G networks are also among the slowest in the world even despite recent upgrades.

Thre is also an evidence of LTE in various states of maturity around the world. Latecomers are launching networks using the latest technology advances and spectrum, and since their networks are still lightly loaded, they?re able to demonstrate some truly astonishing speeds. Meanwhile 4G old timers are starting to suffer from their own success. Their huge subscriber bases are eating up capacity and taxing their network resources. Some like South Korea and Singapore have managed to remain on top through upgrades and plowing more spectrum into their networks, while others are having trouble keeping up.

U.S. LTE status

The U.S. has fallen to No. 55 in LTE performance, according to OpenSignal's report.

The average download speed on U.S. 4G networks inched up to 10Mbps in the June-August quarter. That was an improvement from 9Mbps in the previous quarter, but the country's global ranking fell from 43rd as users in other countries enjoyed much larger gains.

New Zealand scored the highest average speed in the quarter with 36Mbps, coming up from nowhere in the rankings. But perennial standouts like South Korea and Singapore kept getting faster, too. The average LTE speed in Korea is now 29Mbps (up by 4Mbps), and in Singapore it's 33Mbps, up by 5Mbps.

Within the U.S., time coverage and speed varied widely among the major carriers, according to OpenSignal. Verizon was at 84 percent time coverage, followed closely by AT&T at 81 percent, but Sprint hit just 64 percent coverage. T-Mobile USA fell in between with 77 percent.

T-Mobile and Verizon tied for speed at 12Mbps, while AT&T averaged 8Mbps and Sprint came in at 6Mbps.

You can see all of the data and read analysis in the full report.