CMS pixel detector upgrade

Starting in 2013, the Large Hadron Collider (LHC) accelerator at CERN will deliver an increased luminosity, with an eventual goal of reaching 10(35) cm(-')(2)s(-')(1), to the Compact Muon Solenoid (CMS) experiment. This increase will happen in two steps creating far reaching implications for the CMS detector, especially for the tracking system. The first step, Phase I, will double the LHC luminosity and only the pixel tracker detector will be replaced. The second step, Phase II or SLHC, will requi re a new granularity of the strip detector which should substitute its strips with short strips or `strixels'. SLHC will also provide an unprecedented track rate and radiation level that demands a completely new readout architecture. This paper addresses these challenges, focusing on the replacement of the CMS inner pixel detector for Phase I and shows the status of the activities.