The upcoming service will add a new ADSL standard called Annex A.ex to the existing Annex A and Annex C standards supported by BB Technologies using the Yahoo! BB brand name, Yahoo! spokesman Masanori Satake, said.
The technology will allow the subscriber's modem to choose the most suitable of the three standards to use based on the line condition and speed, Satake said. The service has been the subject of trials by 200 users in central Japan since mid-March this year.
Few subscribers are likely to be able to achieve the top speed, but the trial service found that the average user was able to squeeze an extra 1Mbps out of their connection, Satake said. At present, most Japanese ADSL subscribers on 8Mbps services in urban areas enjoy speeds of around 4Mbps to 5Mbps.
A trial of the service involving 3,000 subscribers will begin from 1 July and the company plans to start a commercial service, based on the results of the trial, on 1 August. Users will pay ¥2,080 (£11) for the basic service and modem rental - an increase of ¥400 (£2.20) on the 8Mbps charge - plus an additional ¥1,290 (£7) for Internet service.
The Japanese broadband market will be watching subscriber interest in the service closely. The competitive marketplace was quick to adopt 8Mbps service and the launch of BB Technologies' service just under a year ago gave the market a jolt with its low price. Soon after launch, many competing services slashed their prices to come closer, and the lower prices in turn attracted more users.
According to the Ministry of Public Management, Home Affairs, Posts and Telecommunications (MPHPT), Japan had three million ADSL subscribers at the end of May this year, a large jump from 180,000 subscribers a year earlier.
In contrast, there were 1.5 million cable Internet and 35,000 fibre to the home subscribers at the end of April, the most recent month for which figures are available.