Joint Source-Relay Design for Full-Duplex MIMO AF Relay Systems

Abstract

Abstract-The performance of full-duplex (FD) relay systems can be greatly impacted by the self-interference (SI) at relays. By exploiting multi-antenna in FD relay systems, the spectral efficiency of FD relay systems can be enhanced through spatial SI mitigation. This paper studies joint source transmit beamforming and relay processing to achieve rate maximization for FD MIMO amplify-and-forward (AF) relay systems with consideration of relay processing delay. The problem is difficult to solve due mainly to the SI constraint induced by the relay processing delay. In this paper, we first present a sufficient condition under which the relay amplification matrix has rank one structure. Then, for the case of rank one amplification matrix, the rate maximization problem is equivalently simplified into an unconstrained problem which can be locally solved using gradient ascent method. Next, we propose a penalty-based algorithmic framework, called P-BSUM, for a class of constrained optimization problems which have difficult equality constraints in addition to some convex constraints. By rewriting the rate maximization problem with a set of auxiliary variables, we apply the P-BSUM algorithm to the rate maximization problem in the general case. Finally, numerical results validate the efficiency of the proposed algorithms and show that the joint source-relay design approach under the rank one assumption could be strictly suboptimal as compared to the P-BSUM-based joint source-relay design approach.Index Terms-Full-duplex relaying, MIMO, joint source-relay design, penalty method, BSUM. I. INTRODUCTIONTo simplify transceiver design and reduce implementation cost, traditional relay systems work in half-duplex (HD) mode, where the source and relay transmit signal in two orthogonal and dedicated channels. This inherently results in a waste of channel resources and incurs loss of spectrum efficiency. As compared to the HD relaying, full-duplex (FD) relaying, where the relay node can simultaneously transmit and receive signals over the same frequency band, has potential to approximately double the system spectral efficiency. Hence, with the recent advance of self-interference cancellation technologies, FD relaying has received a great deal of attentions [1]- [5].When the relay operates in the FD mode, the loopback interference, also known as self-interference (SI), occurs due

Spectral Efficiency Optimization For Millimeter Wave Multiuser MIMO Systems

“…A general proof of this theorem can be found in [28]. Note that Robinson's condition is a constraint qualification condition which is often used to characterize the first order optimality condition of nonconvex problems [33]- [37]. For the problem at hand, it is equivalent to the commonly used Mangasarian-Fromovitz constraint qualification (MFCQ) condition.…”

Network Slicing for Service-Oriented Networks Under Resource Constraints

“…In particular, after fixing the values of the binary variables to determine the service instantiation, the remaining flow routing can be realized by solving problem (10), which is an LP problem. To ensure that the routing problem always has a feasible solution, we adopt a strategy similar to PSUM-R, i.e., modify the link capacity constraints by (23) and set the objective function to g + τ ∆.…”

Hardware Impairments Aware Transceiver Design for Full-Duplex Amplify-and-Forward MIMO Relaying

“…• Due to the joint consideration of hardware distortions in the receiver and transmit chains, we observe an interdependent behavior of the relay transmit covariance and the residual self-interference covariance in an FD-AF relay, i.e., the distortion loop effect. Note that this behavior may not be captured from the prior works based on simplified residual interference models, e.g., assuming a perfect SIC via estimation at the receiver [22]- [24], via transmit beamforming [25]- [30], assuming a known self-interference signal with perfect hardware [35], [36], or assuming a known (fixed) residual self-interference covariance [31]- [34]. In Section III, the relay operation is analyzed under the effect of distortion loop, and the instantaneous end-to-end signal-to-distortion-plus-noise ratio (SDNR) is formulated in relation to the statistics of the noise and hardware impairments.…”

“…Moreover, the performance of MuStR1 is improved by introducing an alternating update (AltMuStR1) at the cost of a slightly higher computational complexity compared to MuStR1. Similar to the previous parts, this approach differs from the rank-1 FD-AF relaying schemes proposed in [33,Subsection 3.2] and [30,Section III], where the impact of distortions are not considered in the design of transmit/receive strategies. Numerical simulations show that for a system with a small thermal noise variance, or a high power or transceiver inaccuracy, the application of a distortion-aware design is essential.…”