This　paper　proposes　a　novel　M-ary　differential　permutation　index　(DPI)　differential　chaos　shift　keying　(DCSK)　by　using　the　Bahl-Cocke-Jeline-Raviv　(BCJR)　decoding　(DPI-DCSK-BCJR)　for　chaos-based　communications.　By　exploiting　the　characteristics　of　differential　modulation　and　quasi-orthogonality　of　chaotic　signals,　the　proposed　DPI-DCSK-BCJR　can　provide　two　more　calculated　energies　to　decide　the　transmitted　bits.　Theoretical　analysis　of　bit-error-rate　(BER)　is　carried　out　over　multipath　Rayleigh　fading　channel　and　then　validated　via　simulations.　The　proposed　scheme　is　demonstrated　to　outperform　the　conventional　DPI-DCSK　by　2dB　for　different　M.　This　performance　gain　is　especially　increased　over　high-delay　channels.　Furthermore,　the　advantage　of　the　proposed　frequency-modulated　DPI-DCSK-BCJR　is　verified　over　practical　ultra-wideband　(UWB)　wireless　channels.　In　addition,　we　investigate　the　proposed　DPI-DCSK-BCJR　for　more　generalized　multiuser　communications.　The　simulation　result　shows　that　DPI-DCSK-BCJR　can　achieve　performance　gains　up　to　5dB　as　compared　to　the　conventional　PI-DCSK　and　DPI-DCSK　for　both　two　and　three　user　systems.　Consequently,　the　proposed　DPI-DCSK-BCJR　can　be　considered　as　a　low-cost　alternative　for　low-complexity　and　high-rate　chaotic-based　wireless　communication.