No abstract

In this paper, some methods allowing automatic discrimination between the types of modulations proposed by the DPRS communication standard are presented. In a non-cooperative context, the receiver must first be able to detect the presence of a modulated signal before eventually carrying out its demodulation (i.e. having access to the information). For this purpose a receiver capable of identifying digital modulations of type M-QAM, 8-PSK and GMSK, proposed by the ETSI-DPRS standard, has been studied. Three detection algorithms have been investigated. The first is based on the observation of the amplitude histograms, the second on the continuous wavelet transform and the third on the maximum likelihood for the joint probability densities of phases and amplitudes. Their performance has been evaluated against signal to noise ratio.

No abstract

SUMMARYA receiver based on the parallel cancellation of multiple access interference by bias compensation is considered here for a direct sequence unipolar optical code division multiple access (DS-OCDMA) system. It relies on the estimation of interferences from undesired users, the regeneration of interfering signals at the output of first canceller stage and their substraction from the received signal after amplification by a bias compensation factor in the second stage. The performance of such a technique is analysed in a synchronous network using orthogonal optical codes and the results are compared with those for different types of conventional receivers.

No abstract