## 1 Introduction
Without lack of generalizability, and to ease the understanding, we will assume the BS is placed in a Low Earth Orbit (LEO) satellite, with an altitude between 200 and 2000 km. CB transmissions are based on the constructive interference of the signals emitted by each of the motes, so that the signal is added in phase in certain directions, generating a gain similar to that obtained in an antenna array. But in a CB transmission, the generators, which are the motes of the WSN, are independent and each one of them should send the same pass-band signal, with the appropriate offset. In an antenna array, there is a single generator for the band-pass signal, and this signal is distributed by the phase shifters that lead to the antennas of the array. In the classic beamforming we have a single generator, while in CB we have a group of independent generators. The advantage of the CB is that it allows us to use the motes as independent radiators, which is an economic and simple technology to implement, while the classic beamforming employs a single oscillator with expensive electronics. In a CB transmission, one could theoretically emit from all the motes, which are independent radiant elements, and since the motes are spatially distributed throughout the area where the WSN is deployed, this area would in principle be almost unlimited. In the case of a cluster of antennas, the dimensions of the cluster determine the pointing capability and ultimately the gain of the cluster. Large antenna arrays have an extraordinary gain, which allows them to sweep the space with a \"pencil beam\" in radar systems. This improves the possibilities of CB transmission of a WSN, with a large number of motes, spread over a large area, especially considering the eventual cost of such a deployment compared to an antenna of such dimensions. However, CB transmission has not ceased to be a chimera in the face of the challenges posed to the hardware with which the motes are constituted, as can be seen in [8; 9; 10; 11; 12; 13], mainly due to inaccuracy of their clocks and their synchronization. We must not forget that they are very economical devices that have not been designed for this purpose, and we must devise the procedure that would allow us to obtain CB with the limitations imposed by its architecture [14]. In order to achieve the typical pointing of beam-forming applications, delays of the order of a fraction of the wavelength or very small delay times (a small fraction of nanoseconds) are necessary. These small delays are impossible to achieve with the motes currently available on the market [14]. A fixed pointing would be possible if the clocks of the motes could be synchronized, with zero offset for all the motes; the fixed pointing would be achieved with the spatial delays associated with the special separation of the motes. This would require a meticulous spatial deployment by adequately controlling the special position of each mote. Even so, it would be difficult due to the errors of synchronization of the motes mentioned above [14] as well as the lack of the perfect location. Finally, we analyze the viability of these possibilities and propose a form of transmission named Stochastic Cooperative Beamforming (SCB), where it would be possible to achieve pointing gain without the need to demand great features to motes hardware. The rest of this paper is structured as follows. In Section 2 we put in context the work previously done related to CB, in Section 3 we measure WSN communications in a real deployment. In Section 4 we describe the SCB and its implementation. Finally, in Section 5 we conclude the paper.