MDD-Enabled Two-Tier Terahertz Fronthaul in Indoor Industrial Cell-Free Massive MIMO

by   Bohan Li, et al.

To make indoor industrial cell-free massive multiple-input multiple-output (CF-mMIMO) networks free from wired fronthaul, this paper studies a multicarrier-division duplex (MDD)-enabled two-tier terahertz (THz) fronthaul scheme. More specifically, two layers of fronthaul links rely on the mutually orthogonal subcarreir sets in the same THz band, while access links are implemented over sub-6G band. The proposed scheme leads to a complicated mixed-integer nonconvex optimization problem incorporating access point (AP) clustering, device selection, the assignment of subcarrier sets between two fronthaul links and the resource allocation at both the central processing unit (CPU) and APs. In order to address the formulated problem, we first resort to the low-complexity but efficient heuristic methods thereby relaxing the binary variables. Then, the overall end-to-end rate is obtained by iteratively optimizing the assignment of subcarrier sets and the number of AP clusters. Furthermore, an advanced MDD frame structure consisting of three parallel data streams is tailored for the proposed scheme. Simulation results demonstrate the effectiveness of the proposed dynamic AP clustering approach in dealing with the varying sizes of networks. Moreover, benefiting from the well-designed frame structure, MDD is capable of outperforming TDD in the two-tier fronthaul networks. Additionally, the effect of the THz bandwidth on system performance is analyzed, and it is shown that with sufficient frequency resources, our proposed two-tier fully-wireless fronthaul scheme can achieve a comparable performance to the fiber-optic based systems. Finally, the superiority of the proposed MDD-enabled fronthaul scheme is verified in a practical scenario with realistic ray-tracing simulations.


Enabling Cell-Free Massive MIMO Systems with Wireless Millimeter Wave Fronthaul

Cell-free massive MIMO systems have promising data rate and uniform cove...

Integrated Access and Backhaul in Cell-free Massive MIMO Systems

One of the major challenges with cell-free (CF) massive multiple-input m...

Subframe resource optimization for massive machine device access in LTE networks

Synchronous massive machine device access can lead to severe congestion ...

Graph Neural Network Based Access Point Selection for Cell-Free Massive MIMO Systems

A graph neural network (GNN) based access point (AP) selection algorithm...

Spectral-Efficiency of Cell-Free Massive MIMO with Multicarrier-Division Duplex

A multicarrier-division duplex (MDD)-based cell-free (CF) scheme, namely...

UxNB-Enabled Cell-Free Massive MIMO with HAPS-Assisted Sub-THz Backhauling

In this paper, we propose a cell-free scheme for unmanned aerial vehicle...

Downlink Precoding for Cell-free FBMC/OQAM Systems With Asynchronous Reception

In this work, an efficient precoding design scheme is proposed for downl...

Please sign up or login with your details

Forgot password? Click here to reset