Diversity techniques with multi-h CPM for satellite mobile systems

Abstract

In future mobile satellite systems, a large number of users will have to share the available resources. In order to make possible the existence of truly global and integrated systems it is necessary to use modulations that are both power and bandwidth efficient and that can be used both in the satellite and terrestrial segments of future mobile networks. If this can be achieved, the use of dual-mode terminals will be easier and the handheld cost will be minimised, In this paper, two different multi-h CPM schemes are considered in combination with different types of receiver diversity for the land mobile satellite communication channel. A comparison is made for three types of diversity: selection combining (SC), a post-detection scheme which employs two orthogonal filter banks (for computing metrics) and two Viterbi MLSE decoders followed by post-demodulation selection diversity (PDS) and maximal ratio combining (MRC). Results show that multi-h CPM can achieve good performances when using receiver diversity both in terms of bit error rate and occupied bandwidth. The best results are obtained for the MRC that allows a large gain over the other considered diversity schemes.