"The supplementary statement of objections sent today focuses on certain elements of the "price-cost" test applied by the Commission to assess the extent to which UMTS baseband chipsets were sold by Qualcomm at prices below cost," the European Commission said.
The EU enforcer had in 2015 accused Qualcomm of abusing its market power to thwart Icera between 2009 and 2011, following a complaint from Icera.
Qualcomm expressed disappointment with EU antitrust regulators' decision.
"While the investigation has been narrowed, we are disappointed to see it continues and will immediately begin preparing our response to this supplementary statement of objections," Qualcomm general counsel Don Rosenberg said in a statement.
"We believe that once the Commission has reviewed our response it will find that Qualcomm's practices are pro-competitive and fully consistent with European competition rules," he said.
Qualcomm can face a fine up to 10 percent of its worldwide turnover if found guilty of breaching EU antitrust rules. It was hit with a 997-million-euro ($1.2 billion) penalty in January this year for paying Apple to use only its chips in a bid to squeeze out rival Intel and others.