AT&T scored the highest among top U.S. carriers in a newly released study of mobile video streaming performance.

Global Wireless Solutions said its analysts conducted about 500,000 streaming video tests during the course of driving some 400,000 miles across all 50 states, Puerto Rico and the U.S. Virgin Islands. Its report evaluated the four major domestic carriers based on video loading speeds, picture quality, video freezes and stream reliability.

AT&T led the overall rankings and finished first in reliability, quality and lowest percentage of picture freezing. Videos streamed over its network were successfully completed 98 percent of the time and only froze 0.82 percent of the time.

The telecom giant ranked second in video loading times.

Verizon finished second overall despite coming in third in three categories — loading time, freezing and quality — and finishing second in stream reliability only.

T-Mobile ranked third but led the major carriers in video loading times — at an average of 3.2 seconds — and finished second in freezes and video quality. The carrier ranked third in reliability.

Sprint finished in fourth place across all categories. Videos on Sprint's network loaded in nearly four seconds on average, froze 2 percent of the time and failed at an 8.5 percent clip.

GWS CEO Paul Carter said the report showed gaps between carriers as mobile video becomes increasingly important. Video is expected to fuel a seven-fold increase in data traffic by 2023, he noted.

"Considering that mobile networks are underpinning a revolution in how consumers watch TV and video, this gap should be watched closely," Carter said in a statement.