Direct detect modulations of high speed indoor diffused infrared wireless transmission

High speed indoor diffused infrared wireless transmission is greatly needed for data and multimedia applications. We investigated the error rate performance of OOK (on off keying), NRBI (non-return-to zero with bit insertion), M-ary PPM (pulse position modulation), and two novel coded direct detect modulations, DCGPPM (differentially coded and guarded PPM) and MRLC (modified run length code), by adopting representative channel modeling from measurements and simulations. Practical implementation issues have been further considered. From our results, we suggest DCGPPM at 10 M bps, 4-ary PPM or DCGPPM at 20 M bps, OOK or NRBI at 40 M bps; and MRLC at 100 M bps, for the baseband direct detect transmission of indoor wireless optical transmission.