A Performance Study of Massive MIMO Heterogeneous Networks with Ricean/Rayleigh Fading

摘要

Massive multiple-input and multiple-out (massive MIMO) systems and heterogeneous networks (HetNet) are envisioned to meet the new performance objectives of evolving networks. Now, the main challenge of massive MIMO with HetNet in two-tier networks is how to alleviate interference generated by the randomly deployed femtocells to the macro cells. In this paper, we investigate massive MIMO with HetNet, where the intended macro base station (MBS) transmission follows Ricean fading and interfering femto BS transmissions follow Rayleigh fading. Then, by exploiting matrix and stochastic geometric tools, we derive tight approximations for the intended signal power and aggregated interfering power signal. And derive the signal-to-interference (SIR) with the convolution of the two power signals. Then, we obtain the performance objectives: coverage and outage probabilities, and area spectral efficiency. Further, to reduce the cell edge effects and improve the SIR, we study the role of massive MIMO beamforming coordination with the high-powered MBSs. Thus, we develop maxi-min optimization to control the MBS transmit power. Numerical results show that the coverage and outage performance converge for different user locations, pathloss and Ricean factor. The monotonic increase in Ricean factor improves the SIR of a user located within coverage region. Optimal values of macro BS antenna and transmit power guarantee rate-fairness between the coordinating MBSs, and avoid strong Ricean channel correlation. Also, the performance gain is dependent on the user location, but independent of the cell size.