Hybrid MIMO-OFDM for Downlink Multi-User Communications Over Millimeter Channels with no Instantaneous Feedback

Hybrid Beamforming and Resource Allocation Designs for mmWave Multi-User Massive MIMO-OFDM Systems on Uplink

“…Therefore, the objective function in (24) or the set 𝐶 becomes an empty set; that is, all MSs have already been assigned 𝑁 𝑅𝐹 𝑀𝑆 RF chains. The analog beamformer sets the spatial beamforming direction [48]. Therefore, the result of streams assignment can be obtained from the above RF chains allocation, i.e., (𝑛 𝑠,𝑢 = 𝑁 𝑅𝐹,𝑢 ) 𝑢=1 𝑈 .…”

Decoupling Energy Efficient Approach for Hybrid Precoding-Based mmWave Massive MIMO-NOMA With SWIPT

“…To solve the Lagrange dual issue mentioned earlier, we first optimize the PS factor 𝜷 using the provided dual variables (𝝀, 𝝁, 𝝊) using the gradient ascent technique, and then update the dual variables (𝝀, 𝝁, 𝝊) with the optimized 𝜷 using a wellknown sub-gradient methodology [34] to obtain the optimal. 1) We find the gradient direction of the Lagrange objective function in (46) regarding to power splitting factor 𝛽 𝑚 ∀ m to optimize the 𝛽 𝑚 with given variables (𝝀, 𝝁, 𝝊) as follows ) − 𝑝 𝑔,𝑚 𝑟𝑒𝑞 ) (46) where 𝐴 𝑔,𝑚 and 𝐵 𝑔,𝑚 are defined in (33) and (34), respectively. Particularly, 𝛽 𝑚 can be updated using the following formula 𝛽 𝑚 (𝐼𝑡𝑟 + 1) = 𝛽 𝑚 (𝐼𝑡𝑟) + 𝜀(𝐼𝑡𝑟)∇ 𝛽 𝑚 (𝐼𝑡𝑟) 𝚼 (47) where 𝛽 𝑚 (𝐼𝑡𝑟 ) and 𝛽 𝑚 (𝐼𝑡𝑟 + 1) represent the 𝛽 𝑚 in the 𝐼𝑡𝑟-th and (𝐼𝑡𝑟 + 1)-th iterations, respectively.…”

“…Improved spectrum efficiency, along with improvements in energy efficiency, are among the most key performance indicators (KPIs) for 5G, which are projected to result in an approximately 100-fold increase in spectral efficiency compared to present 4G wireless communications. Toward this end, SWIPT, presented for the first time in [45], has gained wide acceptance in the last few years [46], [47]. SWIPT proposes that the same received RF signals may include both information and energy, and that this may be accomplished using power-splitting receivers in practice.…”