PayPal, an eBay Inc. subsidiary, has updated its mobile 2011 projection to $3 billion, marking the third time it has had to change its mobile predictions for this year, Mobile Commerce Daily reported.

The news comes after a study from Forester Research predicted that mobile commerce will total $6 billion in 2011 and hit $31 billion by 2016. That means PayPal will be responsible for half of all generated mobile commerce revenue this year.

The company claims that merchants see sales increase by 37 percent when using PayPal’s mobile platforms. Last year, more than 5 million customers used PayPal’s mobile products, generating $750 million in total payment volume.

PayPal faces growing competition. Google Inc. has announced Google Wallet, a payment device that lets users pay for items on their mobile devices. Isis is planning to roll out its mobile commerce program during the first half of 2012 to let users purchase and redeem offers on their phones.