Joint Millimeter-Wave Beamforming Design and Access Link Rate Assignment for Integrated Access and Backhaul Networks

When the wireless networks become large, it is hard to connect all base stations (BSs) to the core networks via the wired backhaul due to the increased infrastructure cost. Therefore, the integrated access and backhaul (IAB) networks, where the BS connects to the core networks via the wireless backhaul, has been emerged. In this paper, we consider a millimeter wave (mmWave) beamforming design and backhaul rate assignment in IAB networks. On top of this system model, we derive a closed form expression of the expected sum data rate. Moreover. we formulate the expected sum data rate maximization problem concerning the beamforming design and backhaul rate assignment. Since the formulated problem is a complex form and coupled with the optimization variables, we define a slack variable and divide the original problem into two subproblems. Then, we propose an iterative algorithm to obtain the optimal solution. Moreover, we provide a low-complex algorithm for large-scale networks by using a genetic algorithm (GA)-based approach. Finally, from numerical simulations, we show that the proposed solutions achieve a higher achievable sum data rate than the baseline schemes. We also explore the impacts of the bandwidth partitioning ratio, the biased factor ratio, the density of the user and the number of macro base station (MBS)’s transmit antennas on the achievable sum data rate.