5 research outputs found
Hardware Impairments Aware Transceiver Design for Full-Duplex Amplify-and-Forward MIMO Relaying
In this work we study the behavior of a full-duplex (FD) and
amplify-and-forward (AF) relay with multiple antennas, where hardware
impairments of the FD relay transceiver is taken into account. Due to the
inter-dependency of the transmit relay power on each antenna and the residual
self-interference in an FD-AF relay, we observe a distortion loop that degrades
the system performance when the relay dynamic range is not high. In this
regard, we analyze the relay function in presence of the hardware inaccuracies
and an optimization problem is formulated to maximize the signal to
distortion-plus-noise ratio (SDNR), under relay and source transmit power
constraints. Due to the problem complexity, we propose a
gradient-projection-based (GP) algorithm to obtain an optimal solution.
Moreover, a nonalternating sub-optimal solution is proposed by assuming a
rank-1 relay amplification matrix, and separating the design of the relay
process into multiple stages (MuStR1). The proposed MuStR1 method is then
enhanced by introducing an alternating update over the optimization variables,
denoted as AltMuStR1 algorithm. It is observed that compared to GP, (Alt)MuStR1
algorithms significantly reduce the required computational complexity at the
expense of a slight performance degradation. Finally, the proposed methods are
evaluated under various system conditions, and compared with the methods
available in the current literature. In particular, it is observed that as the
hardware impairments increase, or for a system with a high transmit power, the
impact of applying a distortion-aware design is significant.Comment: Submitted to IEEE Transactions on Wireless Communication
Simultaneous wireless information and power transfer in full-duplex communication systems
As wireless devices are mostly constrained by their inability to operate independently infinitely away from centralised power sources, radio frequency (RF) energy harvesting (EH) has been identified as a promising technique for future wireless devices. For this reason, this thesis introduces a novelty in RF EH full-duplex (FD) wireless communication systems. Specifically, this thesis investigate the potentials of simultaneous wireless information and power transfer (SWIPT) in FD communication systems. This thesis firstly focuses on optimal transmit strategies, rate maximization and power minimizing approach for SWIPT in FD systems. Using the rate-split method, difference of convex programming, semi-definite programming technique and one-dimensional search, we reformulate complex optimization problems to yield problem formulations that can be efficiently solved, thus we develop rate maximization algorithm for SWIPT in a point-to-point FD system, SWIPT in FD multiple-input multiple-output (MIMO) two-way relay system and power minimization approach for SWIPT in a multiuser MIMO FD system. This thesis also presents research work carried out with the aim of maximising the secrecy sum-rate for SWIPT in FD systems. In this context, we employ the use of an amplify and forward (AF) relay to inject artificial noise (AN) in order to confuse the eavesdropper. Thus, we address the optimal joint design of the beamforming matrix and AN covariance matrix at the relay, and the transmit power at the sources. Comprehensively, we present extensive theoretical and computer simulations to corroborate the need for joint optimization