Projecte de final de carrera realitzat en col.laboració amb Beijing Institute of Technology

This thesis is based on the study of the BER in link level of a cellular CDMA platform developed by Wireless Reserch Group of BIT. For that, and firstly, we have focused on the theory relative to the spread spectrum communications systems. Later, and taking into account that the main goal of the thesis is the empirical comprovation of the improvements introduced by Alamouti technique in the platform, general review of diversity fundamentals are also given, plus a detailed discussion about the Alamouti technique. This first part of the thesis corresponds to the revision of all this concepts, papers and literature, hence it has theoretic orientation.On the other hand, and much more practical, we have built an Alamouti transmiter/receiver using the RUNE toolbox of Matlab. This implementation, whose details and characteristics can be consulted later on, has the goal to show, in the most clearly way, the impact of using the Alamouti technique in the link level performance. Such impact will be obtained from several simulations under some differents settings, whose results will be presented and analized in detail. We will elaborate a set of final conclusions as well