R&D; towards future upgrade of the CMS RPC system

The CMS experiment at the CERN Large Hadron Collider (LHC) is equipped with a redundant muon trigger system based on Drift Tubes Chambers (DT) in the barrel region and Cathode Strip Chamber (CSC) in the endcap regions and Resistive Plate Chambers (RPC) in both regions up to | η | = 1.6. In view of the High Luminosity LHC (HL-LHC) phase, to keep the same muon performance new muon stations will be installed in the forward region (1.6< | η | <2.4) and in the very forward region up to | η | = 2.8. The 3th and 4th stations will be equipped with a new generation of RPC with improved performance (iRPC), capable of handling the challenging con- ditions expected at the HL-LHC. An extensive R&D; program has been undertaken to define the detector design and related electronics that meet the HL-LHC requirements. A summary of iRPC performance results is here reported.