  Systems of small distributed satellites in low Earth orbit (LEO) transmitting
cooperatively to a multiple antenna ground station (GS) are investigated. These
satellite swarms have the benefit of much higher spatial separation in the
transmit antennas than traditional big satellites with antenna arrays,
promising a massive increase in spectral efficiency. However, this would
require instantaneous perfect channel state information (CSI) and strong
cooperation between satellites. In practice, orbital velocities around 7.5 km/s
lead to very short channel coherence times on the order of fractions of the
inter-satellite propagation delay, invalidating these assumptions. In this
paper, we propose a distributed linear precoding scheme and a GS equalizer
relying on local position information. In particular, each satellite only
requires information about its own position and that of the GS, while the GS
has complete positional information. Due to the deterministic nature of
satellite movement this information is easily obtained and no inter-satellite
information exchange is required during transmission. Based on the underlying
geometrical channel approximation, the optimal inter-satellite distance is
obtained analytically. Numerical evaluations show that the proposed scheme is,
on average, within 99.8% of the maximum achievable rate for instantaneous CSI
and perfect cooperation
