This paper introduces a hybrid pilot-aided channel estimation technique formitigating the effect of pilot contamination for the uplink of multi-cellmultiuser massive MIMO systems. The proposed hybrid pilot is designed such thatit enjoys the complementary advantages between time-multiplexed (TM) pilot andtime-superimposed (TS) pilot, and thereby, allows superior solution to theconventional pilot schemes. We mathematically characterize the impact of hybridpilot on the massive MIMO uplink by deriving a closed-form approximation forthe uplink achievable rate. In large-number-of-antennas regime, we obtain theasymptotically optimal solution for hybrid pilot by jointly designing the TMpilot and the TS pilot. It is shown that either TM pilot or TS pilot has theadvantages for large frame-size and limited frame-size transmission,respectively, while the hybrid pilot scheme can offer a superior performance tothat employing either TM pilot or TS pilot. Numerical results demonstrate theeffectiveness of the proposed design.
展开▼
