Downlink Training Sequence Design Based on Waterfilling Solution for Low-Latency FDD Massive MIMO Communications Systems

Future generations of wireless communications systems are expected to evolve toward allowing massive ubiquitous connectivity and achieving ultra-reliable low-latency (URLLC) with extremely high data rates. Massive multiple-input multiple-output (m-MIMO) is a crucial transmission technique fulfill the demands rates in upcoming systems. However, obtaining downlink (DL) training sequence (TS) that feasible for fast channel estimation, i.e., meeting required by future systems, m-MIMO frequency-division-duplex (FDD) when users have different correlations very challenging. Therefore, low-complexity solution designing DL sequences maximize achievable sum rate FDD limited coherence time (CCT) proposed using waterfilling power allocation method. This maximization achieved produced from summation user’s covariance matrices then applying method obtained sequence. The results show TS outperforms existing methods medium SNR regimes while reducing computational complexity. signify TS’s feasibility practical consideration compared designs.