Abstract :
[en] This paper studies the non-orthogonal multicast and
unicast coordinated beamforming design for integrated terrestrial
and satellite networks (ITSN), when the channel state information
at the transmitter (CSIT) is imperfect. In order to mitigate the
interference induced by simultaneous multicast and unicast links
along with the spectrum coexisting mechanism for integrated
terrestrial and satellite transmissions, we consider a two-layer
layered division multiplexing (LDM) structure where the mul ticast and unicast services are provided in different layers. We
formulate a coordinated beamforming problem with the objective
to minimize the transmit power under individual quality of
service (QoS) constraints. With regard to the unknown convexity
of the transmit power minimization problem, we transform the
original infeasible optimization into a deterministic optimization
form with linear matrix inequality (LMI) by utilizing S-procedure
and semi-definite relaxation (SDR) methods. Then, we introduce
a penalty function and propose an iterative algorithm with
guaranteed convergence to obtain optimal solutions. Simulation
results demonstrate the superiority of the proposed coordinated
beamforming scheme, especially for the case of imperfect CSIT,
while our LDM based coordinated beamforming scheme signifi cantly outperforms the conventional ones in terms of sum rate.
Index Terms—Integrated terrestrial and satellite networks (IT SN), beamforming, robust, layered division multiplexing (LDM)
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