Japan's KDDI and vendor NEC have begun an LTE trial on the 1.5GHz band ahead of a planned commercial launch in 2012.
The companies are trialing LTE transmissions in an urban area with high population density, NEC said.
The trial commenced last month, and is concentrating on handover performance in areas of heavy radio interference.
The parties previously co-operated on a field trial in the less-heavily populated Nasushiobara area, running from March to August.
KDDI, which now runs 2G and 3G CDMA networks, plans to launch LTE services in both the 1.5GHz and 800MHz bands from December 2012. The company aims to expand its mobile broadband coverage area to 96.5% of Japan by the end of March, 2015.
KDDI awarded LTE rollout contracts to NEC and Motorola in August last year. Under the arrangement, KDDI will use NEC base stations for the first time.
NEC last month revealed it had completed an LTE trial with Globe Telecom in the Philippines.