  We investigate a multi-pair two-way decode-andforward relaying aided massive
multiple-input multiple-output antenna system under Rician fading channels, in
which multiple pairs of users exchange information through a relay station
having multiple antennas. Imperfect channel state information is considered in
the context of maximum-ratio processing. Closedform expressions are derived for
approximating the sum spectral efficiency (SE) of the system. Moreover, we
obtain the powerscaling laws at the users and the relay station to satisfy a
certain SE requirement in three typical scenarios. Finally, simulations
validate the accuracy of the derived results.
