According to a study by research firm Juniper, the North American market for mobile games could exceed $3 billion by 2012. Juniper estimates the mobile game market for 2007 in North America represents less than $800 million.

Currently around 18 million Americans download or rent mobile games at least once per year, but Juniper says improvements in the user interface, flat rate data and free trials will boost the user base.

“This try-before-you-buy strategy not only makes the customer more comfortable about purchasing a particular title: it also makes him or her more familiar with mobile gameplay per se, and will provide further encouragement for the consumer to seek out additional titles in the future,” said Windsor Holden, the report’s author, in a statement.

Juniper also estimates that the proportion of ad-funded mobile game downloads will reach 30% by 2012.