Mixed Time Scale Weighted Sum Rate Maximization for Hybrid Beamforming in Multi-Cell MU-MIMO Systems

Hierarchical optimization: A hybrid processing for downlink massive MU‐MIMO mmWave systems

“…The digital part of the hybrid precoder is computed by two stages as F BB = F BB ∈ ℂ N RF t ×KN s , we consider a baseband MMSE filter, whose expression was properly derived in [20] and [32] as follows…”

“…Although these last works offer low latency and decrease channel estimations procedures, they have poor performance in terms of bit error rate (BER) or sum rate compared with adaptive techniques. References [18][19][20] present a hierarchical strategy to divide the hybrid processing problem into analog and digital subproblems. In this strategy, the analog part of the hybrid precoder/combiner is typically computed first.…”

Approximate expressions for BER performance in downlink mmWave MU‐MIMO hybrid systems with different data detection approaches

“…Thus, when the number of antennas is very large, the high cost and power consumptions of the mixed signal components is highly inefficient. In order to surpass these drawbacks, beamforming design with lower number of RF chains than antenna elements has received significant attention for the last years [1–5].…”

On Hybrid Beamforming Design for Downlink Mmwave Massive Mu-Mimo Systems

“…On the other hand, typical approaches for the designing of the analog parts of both the combiner and the precoder are focused on increasing the signal-to-noise ratio (SNR) or the signal-to-interference-plus-noise ratio (SINR) but without presenting bit error rate (BER) results, e.g., [49,50]. In this chapter we propose two simple solutions that are enable decreasing the inter symbol interference while keeping SNR large.…”

“…Note that the considered MMSE filter in the step 4 is a pseudo MMSE linear precoder. A more appropriate expression for the MMSE filter has been demonstrated in [50] and for completeness purpose the deduction applied in our proposals is showed in Appendix A.…”