Space-time-block-code　(STBC)　and　wideband　permutation　index　differential-chaos-shift-keying　(PI-DCSK)　modulation　can　effectively　mitigate　the　multipath　fading.　By　integrating　STBC　with　PI-DCSK,　we　propose　an　M-ary　space-time-block-code　shift　index　differential-chaos-shift-keying　(STBC-SI-DCSK)　scheme.　This　scheme　leverages　low　correlation　between　chaotic　signals　to　minimize　inter　antenna　interference　and　achieve　full　diversity　gain.　Simulation　results　show　that　the　proposed　scheme　improves　bit-error-rate　(BER)　by　about　10　dB　and　5　dB　over　single-input　single-output　(SISO)-aided　PI-DCSK　(SISO-PI-DCSK)　and　STBC-PI-DCSK,　respectively,　at　a　BER　of　10-4.　The　proposed　STBC-SI-DCSK　scheme　also　demonstrates　superior　BER　performance　in　ultra-wide　bandwidth　(UWB)　channels　while　simplifying　the　permutation　operation.　This　results　in　a　transceiver　complexity　comparable　to　that　of　SISO-PI-DCSK,　making　it　well-suited　for　wireless　local　area　network　(WLAN)　applications.　　©　1967-2012　IEEE.