NTT DoCoMo has selected nine partners for a new keyword search feature to be included at the top of the i-Mode homepage. The prime location is one of the most valuable pieces of screen real estate in Japan, reaching DoCoMo’s 46.7m i-Mode subscribers.

It will enable customers to search the official i-Mode sites (of which there are about 6200), the numerous unofficial sites and information on the wider internet.

MSN is the only global search engine brand chosen for the new feature, while Google and Yahoo are noticeably absent from the list of partners.

Microsoft’s relationship with the Japanese operator has been improving in recent months, with DoCoMo launching a number of Windows Mobile-based handsets and experimenting with Microsoft’s DRM technology for mobile music downloads.

Access to the ever expanding range of mobile internet content is becoming a significant challenge for network operators. Directory-based structures, which organise content in hierachal levels, are proving inadequate because users seem unwilling to stray far from the first couple of layers. The result is a viscious circle in which those companies excluded from the prime spots cannot get enough traffic to survive and service development is concentrated on a few ‘tier one’ players who get access to the top level of the hierachy.

Search engines are one way of improving content discovery on mobile handsets, but most have been designed with desktop computers in mind, where the dynamics of input and usage time are very different.

There are also strategic considerations, with many network operators concerned by the mobile ambitions of the major search engines. Operators currently command a hugely influential position in the value chain because they control the homepage; if search engines become the most popular method of access, operators could lose this key strategic asset. Portals such as Google, MSN and Yahoo can also leverage users’ affinity for existing services, such as Gmail and Hotmail, to attract mobile subscribers.

However, some operators are embracing the opportunity and pre-empting competitive tensions by agreeing partnerships with the portals. Earlier this year Vodafone and Google signed a deal which will see the world’s largest operator linking to the search engine from its mobile internet homepage.

Google has made no secret of its mobile ambitions, launching versions of its Mail, Maps and Froogle services for mobile customers. Users can also access their Google personal homepage from their mobile device.

The portal’s search technology optimises web pages so they can be viewed more easily on the small screen of a handset. This has raised concerns among both operators and content providers, as it hands defacto control of the user experience to Google.

The result is a market where the ambitions of various factions throughout the value chain are delicately balanced while each weighs the benefits of future collaboration. DoCoMo, in choosing its search partners, appears to have focused on maintaining tight control over its content experience.