We study a relay-aided downlink cellular network with one
NB-antenna BS, L MIMO FDRs, and L single-antenna users,
as illustrated in Fig. 1. Each FDR is equipped with Nt transmit
antennas and Nr receive antennas, and performs decode-andforward
transmission to avoid noise/interference amplification.
IRI is considered between any two relays. Similar to [18] [19],
we assume that the direct links between the BS and the users
are ignored due to severe path loss and blockage. Typically,
the users are dispersed geographically in a cell and associated
with different relays. While more than one user may exist in
each relay’s coverage, we consider a simplified model where
each relay selects only one user to serve1: the data intended
for user i is first received and decoded by relay i on feeder
link i, and then re-encoded and forwarded to user i on access
link i. To account for the case that users can possibly be
located at the coverage overlap of adjacent relays, MUI is
considered for each user from relays other than its serving
relay. This model can be prospectively extended to the more
general scenario with multiple users served by each relay in a multi-cell network, which is left for future works.