R. Alves and A. Gameiro (Portugal)
Infrared, PPM, TCM coding, rate adaptation.
In this communication we consider the use of PPM based
modulation methods, such as the hybrid modulation
method called Amplitude and Pulse-Position Modulation
(APPM) and Overlapping Pulse-Position Modulation
(OPPM) to improve the performance of infrared
WLAN’s, by the use of Trellis-Coded Modulation (TCM)
codes. We derive the best codes for some APPM and
OPPM schemes, and the results show that non-negligible
coding gains without bandwidth expansion can be
obtained with trellis codes of moderate complexity. The
theoretical coding gains are confirmed by simulation.
Finally a set of multirate systems using the derived TCM
coding are evaluated, and their practical benefits observed
in terms of connectivity improvements.