2 research outputs found
Robust and Secure Resource Allocation for Full-Duplex MISO Multicarrier NOMA Systems
In this paper, we study the resource allocation algorithm design for
multiple-input single-output (MISO) multicarrier non-orthogonal multiple access
(MC-NOMA) systems, in which a full-duplex base station serves multiple
half-duplex uplink and downlink users on the same subcarrier simultaneously.
The resource allocation is optimized for maximization of the weighted system
throughput while the information leakage is constrained and artificial noise is
injected to guarantee secure communication in the presence of multiple
potential eavesdroppers. To this end, we formulate a robust non-convex
optimization problem taking into account the imperfect channel state
information (CSI) of the eavesdropping channels and the quality-of-service
(QoS) requirements of the legitimate users. Despite the non-convexity of the
optimization problem, we solve it optimally by applying monotonic optimization
which yields the optimal beamforming, artificial noise design, subcarrier
allocation, and power allocation policy. The optimal resource allocation policy
serves as a performance benchmark since the corresponding monotonic
optimization based algorithm entails a high computational complexity. Hence, we
also develop a low-complexity suboptimal resource allocation algorithm which
converges to a locally optimal solution. Our simulation results reveal that the
performance of the suboptimal algorithm closely approaches that of the optimal
algorithm. Besides, the proposed optimal MISO NOMA system can not only ensure
downlink and uplink communication security simultaneously but also provides a
significant system secrecy rate improvement compared to traditional MISO
orthogonal multiple access (OMA) systems and two other baseline schemes.Comment: Submitted for possible publicatio
Max-Min Fairness User Scheduling and Power Allocation in Full-Duplex OFDMA Systems
In a full-duplex (FD) multi-user network, the system performance is not only
limited by the self-interference but also by the co-channel interference due to
the simultaneous uplink and downlink transmissions. Joint design of the
uplink/downlink transmission direction of users and the power allocation is
crucial for achieving high system performance in the FD multi-user network. In
this paper, we investigate the joint uplink/downlink transmission direction
assignment (TDA), user paring (UP) and power allocation problem for maximizing
the system max-min fairness (MMF) rate in a FD multi-user orthogonal frequency
division multiple access (OFDMA) system. The problem is formulated with a
two-time-scale structure where the TDA and the UP variables are for optimizing
a long-term MMF rate while the power allocation is for optimizing an
instantaneous MMF rate during each channel coherence interval. We show that the
studied joint MMF rate maximization problem is NP-hard in general. To obtain
high-quality suboptimal solutions, we propose efficient methods based on simple
relaxation and greedy rounding techniques. Simulation results are presented to
show that the proposed algorithms are effective and achieve higher MMF rates
than the existing heuristic methods.Comment: 15 pages, 8 figures, accepted by IEEE Trans. Wireless Commu