  We study and analyze coverage region in MIMO communication systems for a
multiple-relay network with decode-and-forward (DF) strategy at the relays.
Assuming that there is a line-of-sight (LOS) propagation environment for
source-relay channels and channel state information is available at receivers
(CSIR), we consider the objective of maximizing coverage region for a given
transmission rate and show numerically the significant effect of propagation
environment on capacity bounds, optimal relay location and coverage region.
Also, we study the situation in which two adjacent relays cooperate in
transmission signals to the destination and show analytically that the coverage
region is extended compared to noncooperative scenario.
