In　this　letter,　a　joint　pulse　position　modulation　(PPM)　and　permutation　index　differential　chaos　shift　keying　(PI-DCSK)　modulation　scheme　(PPM-PI-DCSK)　is　proposed　to　increase　the　data　rate　and　improve　performance.　In　PPM-PI-DCSK,　the　bit　stream　is　divided　into　blocks　of　m(p)+m(c)+1　bits,　where　m(p)　bits　are　modulated　by　PPM,　m(c)　bits　are　modulated　by　PI　modulation,　and　the　last　one　bit　is　modulated　by　DCSK.　The　theoretical　bit　error　rate　(BER)　performance　of　the　proposed　PPM-PI-DCSK　is　derived　over　multipath　Rayleigh　fading　channels　and　validated　via　simulations.　Simulation　results　show　that　the　proposed　PPM-PI-DCSK　outperforms　the　benchmark　DCSK-based　schemes.　Furthermore,　the　performance　superiority　is　also　demonstrated　by　the　frequency-modulated　PPM-PI-DCSK　over　a　typical　ultra-wideband　(UWB)　channel.　This　demonstrates　the　superiority　and　feasibility　of　the　proposed　scheme　in　practical　applications.