  This work provides a comprehensive scaling law and performance analysis for
multi-user massive MIMO relay networks, where the relay is equipped with
massive antennas and uses MRC/MRT for low-complexity processing. CSI error is
considered. First, a sum-rate lower bound is derived which manifests the effect
of system parameters including the numbers of relay antennas and users, the CSI
quality, and the transmit powers of the sources and the relay. Via a general
scaling model on the system parameters with respect to the relay antenna
number, the asymptotic scaling law of the SINR as a function of the parameter
scalings is obtained, which shows quantitatively the tradeoff between the
network parameters and their effect on the network performance. In addition, a
sufficient condition on the parameter scalings for the SINR to be
asymptotically deterministic is given, which covers existing studies on such
analysis as special cases. Then, the scenario where the SINR increases linearly
with the relay antenna number is studied. The sufficient and necessary
condition on the parameter scaling for this scenario is proved. It is shown
that in this case, the interference power is not asymptotically deterministic,
then its distribution is derived, based on which the outage probability and
average bit error rate of the relay network are analysed.
