  With the development of wireless communication, higher requirements arise for
train-ground wireless communications in high-speed railway (HSR) scenarios. The
millimeter-wave (mm-wave) frequency band with rich spectrum resources can
provide users in HSR scenarios with high performance broadband multimedia
services, while the full-duplex (FD) technology has become mature. In this
paper, we study train-ground communication system performance in HSR scenarios
with mobile relays (MRs) mounted on rooftop of train and operating in the FD
mode. We formulate a nonlinear programming problem to maximize network capacity
by allocation of spectrum resources. Then, we develop a sequential quadratic
programming (SQP) algorithm based on the Lagrange function to solve the
bandwidth allocation optimization problem for track-side base station (BS) and
MRs in this mm-wave train-ground communication system. Extensive simulation
results demonstrate that the proposed SQP algorithm can effectively achieve
high network capacity for trainground communication in HSR scenarios while
being robust to the residual self-interference (SI).
