mmWave Amplify-and-Forward MIMO Relay Networks With Hybrid Precoding/Combining Design

Abstract

In this paper, we consider the amplify-and-forward relay networks in mmWave systems and propose a hybrid precoder/combiner design approach. The phase-only RF precoding/combining matrices are first designed to support multi-stream transmission, where we compensate the phase for the eigenmodes of the channel. Then, the baseband precoders/combiners are performed to achieve the maximum mutual information. Based on the data processing inequality for the mutual information, we first jointly design the baseband source and relay nodes to maximize the mutual information before the destination baseband receiver. The proposed low-complexity iterative algorithm for the source and relay nodes is based on the equivalence between mutual information maximization and the weighted MMSE. After we obtain the optimal precoder and combiner for the source and relay nodes, we implement the MMSE-SIC filter at the baseband receiver to keep the mutual information unchanged, thus obtaining the optimal mutual information for the whole relay system. Simulation results show that our algorithm achieves better performance with lower complexity compared with other algorithms in the literature. In addition, we also propose a robust joint transceiver design for imperfect channel state information. arXiv:1910.14182v1 [cs.IT] 30 Oct 2019the small wavelength allows integrating many antennas in a small area. Despite its advantages, the mmWave carrier frequencies suffer from relatively severe propagation losses. Meanwhile, the sparsity of the mmWave scattering environment usually results in rank-deficient channels [2].To overcome the large path losses, large antenna arrays can be placed at both transmitters and receivers to guarantee sufficient received signal power [3]. The large antenna arrays lead to a large number of radio frequency (RF) chains, which greatly increase the implementation cost and complexity. To reduce the number of RF chains, hybrid analog/digital precoding has been proposed, which connects analog phase shifters with a reduced number of RF chains. The main advantage of the hybrid precoding is that it can trade off between the low-complexity limitedperformance analog phase shifters and the high-complexity good-performance digital precoding [4].Despite the help of large antenna arrays, the severe propagation losses still limit mmWave communications to take place within short ranges. Fortunately, the coverage can be greatly extended with the help of relay nodes [5]. Therefore, investigating the performance of hybrid precoding/combining in the relay scenario is important. For the conventional relay scenario, network beamforming in amplify-and-forward (AF) relay networks was studied in [6], [7].For a mmWave relay scenario, large antenna arrays are usually implemented to mitigate the severe path loss. In addition, a hybrid precoding method is adopted. There are two typical hybrid precoding structures: (i) fully-connected structure (where each RF chain is connected to all antennas) [8], and (ii) sub-connected structure (where each RF chain ...

Analysis and Optimization for Robust Millimeter-Wave Communications

“…We can distinguish between full-duplex (FD) and half-duplex (HD) relays [63,64,65], depending on whether the relay node can receive and transmit simultaneously or not. Moreover, we can differentiate between amplify and forward (AF) [66] and decode and forward (DF) relays [67]. The latter decodes, re-modulates, and retransmits the received signal, whereas, the former simply amplifies and retransmits the signal without decoding.…”

Deep Learning Framework for Hybrid Analog-Digital Signal Processing in mmWave Massive-MIMO Systems

“…One of the most prominent techniques for designing HSP systems consists in minimizing the Euclidean distance between the desired FD processor and its hybrid counterpart, which is the objective function used for HBF design in [16]- [23]. Particularly, in [16], [17], compressed sensing techniques are employed to exploit sparse characteristics of the mmWave channels while in [18], [19], a manifold optimization algorithm and a simultaneous matrix diagonalization technique are introduced, respectively, to solve the design problem.…”

Hybrid Precoding Design for Two-Way Relay-Assisted Terahertz Massive MIMO Systems

“…For the DF relay, to mitigate the self-interference (SI), a zero space SI cancellation algorithm and an orthogonal matching pursuit-based SI-cancellation precoding algorithm is proposed in [20] and [21], respectively. Further, in [22], the authors have proposed a mixed-connected structure relay system to compromise power consumption and sum-rate performance. These works are limited to mmWave massive MIMO systems.…”