Mobile phone titan Vodafone's upbeat trading statement on Thursday should improve sentiment and encourage a premium rating for the stock, Nomura Research believes. "Vodafone's US exposure should also command a premium given the more co-operative atmosphere at Verizon Wireless," where Vodafone holds a 45% stake. The US mobile phone network is widely expected to resume paying dividends soon, which would provide Vodafone with a welcome additional revenue stream.Nomura said the trading update provided evidence of improving relative performance to Vodafone's peers, with the UK being the main highlight this time round. "Areas of weakness are localised to uncontrolled macro issues," the broker suggested."Data growth picked up to 27% at group level and was stable at 23% in Europe. Rates of smartphone adoption continue to increase rapidly, notably in Italy and Germany this quarter. Overall smartphone penetration of the base is 17% but data attach rates are only 46%. While the attach rates might be seen as disappointing, it also serves to highlight that the smartphone story remains in its infancy," Nomura said.The broker has made some minor tweaks to its earnings forecasts. "We are forecasting group organic growth to fall from 2.1% for fiscal 2011 (FY11) to 0.5% for FY12 before recovering to 2.1% in FY13. We forecast group margin decline by 110bp [basis points] for FY11 and by 10bp for FY12," Nomura said.The broker keeps its "buy" recommendation and target price of 220p.