On the Outage Capacity of Orthogonal Space-time Block Codes Over   Multi-cluster Scattering MIMO Channels
  Multiple cluster scattering MIMO channel is a useful model for pico-cellular MIMO networks. In this paper, orthogonal space-time block coded transmission over such a channel is considered, where the effective channel equals the product of n complex Gaussian matrices. A simple and accurate closed-form approximation to the channel outage capacity has been derived in this setting. The result is valid for an arbitrary number of clusters n-1 of scatterers and an arbitrary antenna configuration. Numerical results are provided to study the relative outage performance between the multi-cluster and the Rayleigh-fading MIMO channels for which n=1. 
Lu Wei, Zhong Zheng, Jukka Corander, and Giorgio Taricco
cs.IT math.IT