Analysis of single and multi carrier modulation schemes for 42 GHz broadband wireless systems

Broadband wireless systems (BWS) are becoming more and more attractive due to the huge available bandwidth they can offer coupled with the intrinsic flexibility and lower costs of radio infrastructures. In the framework of studies carried out within ACTS CRABS European Project, this paper presents an evaluation and comparison of performances between single carrier (QPSK, 16 QAM) and multicarrier (OFDM) modulation schemes in the 42 GHz BWS downlink transmission channel. In order to assess the performances of the schemes proposed, a simulator has been implemented including power amplifier characteristics and modeling the propagation effects under various frequency plans. Overall evaluation of the results, though quite complex is in favour of multicarrier modulation only in case of single frequency distribution networks. For other network configurations (not purely distributive), strong constraints imposed by existing microwave technology and not very dramatic radio propagation conditions advise for single carrier modulation schemes