A multilevel modulation scheme for high-speed wireless infrared communications

To investigate short-distance, point-to-point, infrared channels, a test-bench and circuits were constructed to determine the limitations ofexisting optoelectronics. Theresults ofthesemeasurements are used to formulate a channel model which is employed for the subsequent analysis of candidate bandwidth efficient modulation schemes. A newmultilevel modulation scheme,Adaptively Biased QAM (AB-QAM), is proposedwhich has an asymptotic 3 dB SNR improvement over PAM and a 4.5 dB improvement over QAM for large constellationswhile maintaining the samebandwidthefficiency. Expressions are derived for the performance of each modulation scheme and are verified in simulation.

• Type: Conference
• Year: 1999
• Where: ISCAS
• Authors: S. Hranilovic, D. A. Johns
• Keywords: Bandwidth Efficient Modulation, Hardware, ISCAS 1999, Limitations Ofexisting Optoelectronics, Modulation Scheme