Indian equity benchmarks Sensex and Nifty50 are likely to start Tuesday's session on a positive note. Nifty futures trading on Singapore Exchange -- an early indicator of the Nifty50 index -- were last seen up 17.5 points or 0.1 percent at 18,014.5 ahead of the opening on Dalal Street. Investors globally awaited a key interest rate decision by the Federal Reserve due this week.