This report defines and analyzes a general model of macrodiversity in CDMA networks (Code Division Multiple Access). Some differences between the up link (from users to base stations) and downlink (from base stations to users) lead to two different models which are studied in parallel in this report. In order to satisfy the bit rate requirements of users, it is necessary to make use of a control policy of emitted powers. We prove necessary and sufficient conditions of the existence of a power allocation in the network which satisfies all users. These conditions depend on the users requirements and on the geometry of the network. For a finite network on the downlink, we prove a necessary condition on the optimal power allocation policy. This result shows that macrodiversity has a limited impact on the downlink. The analysis of infinite networks is led in the framework of stationary ergodic point processes. On the uplink, there is a necessary and sufficient condition of the existence of a power allocation which guarantee a given set of bit rate requirements for users. This condition is of type «<1», where is function only of the average bits rate requirement of users and on the average number per unit of surface of users and base stations. On the contrary, on downlink , it is proven that if the location of users in space are realisations of a homogeneous Poisson point process, then almost surely there is no power allocation which satisfy all the users' demands whatever is the position and the density of base stations.