Coordinated pilot reuse for multi-cell massive MIMO transmission

In this paper, we propose a coordinated pilot reuse (CPR) scheme for multi-cell massive multi-input multi-output systems to reduce the pilot overhead. Unlike the conventional pilot reuse scheme which allows pilots to be reused only among different cells, CPR allows inter- and/or intra-cell user equipments to reuse the same pilots, efficiently reducing the pilot overhead. For the spatially correlated Rayleigh fading channels, we first present the CPR-based channel estimation and a greedy pilot allocation algorithm. With the channel estimation errors due to CPR taken into account, we then develop a statistically robust transceiver which can guarantee the transmission performance. Monte-Carlo simulations show that compared to the conventional multi-cell pilot reuse scheme, the proposed CPR scheme provides significant performance gains in terms of the net spectral efficiency.