Linear baseband precoding strategies for millimeter wave MIMO multi-X channels

Abstract

This paper focuses on the design of linear baseband precoding and combining techniques for millimeter wave (mmWave) multiple input multiple output (MIMO) backhaul networks. We consider a scenario known as MIMO multi-X channel with L transmitter base stations and K receiver base stations, each equipped with multiple antennas, where each transmitter base station communicates simultaneously with all receiver base stations. The extremely short wavelength of mmWave requires the use of large antenna arrays at the base stations (BS) to combat the high path loss to achieve sufficiently high link gains, enabled by directional beamforming. As signal processing with large antenna arrays lead to implementations that are associated with high power consumption and high hardware complexity, hybrid (analog/digital) precoding/combining has been proposed recently to overcome these limitations. The design of such hybrid precoders/combiners is typically performed separately for the analog and the digital domains. In this work, we propose several novel low-complexity schemes suited for the digital part of such hybrid precoders/combiners. Our solutions are based on block-diagonalization and minimum mean squared error (MMSE) techniques and assume the availability of partial knowledge of CSI at each BS in the network. Finally the simulation results demonstrate the potential gains of the proposed algorithms

Antenna array configurations for terrestrial backhaul links at Ka-band frequencies

“…To achieve better performance, hybrid analog-digital solutions were suggested e.g. in [3]- [7]. In our papers [6], [7], we focused on the digital step of the hybrid analog-digital BF.…”

“…in [3]- [7]. In our papers [6], [7], we focused on the digital step of the hybrid analog-digital BF. Our approaches exploit block diagonalization and MMSE techniques that require full channel state information (CSI) [6] or a partial CSI [7].…”

“…In our papers [6], [7], we focused on the digital step of the hybrid analog-digital BF. Our approaches exploit block diagonalization and MMSE techniques that require full channel state information (CSI) [6] or a partial CSI [7]. Performance of the proposed interference mitigation techniques was demonstrated in selected 2D scenarios by assuming isotropic radiating elements with perfect cross polarization discrimination (XPD).…”

Spectrum sharing in hybrid terrestrial-satellite backhaul networks in the Ka band

“…This scenario can be understood as a multi-point to multipoint case (MPTTMP) and is referred as K-user MIMO X network in the literature [10]. Unlike the precoding schemes based on decomposing the K-user MIMO X network [11] , we first propose a simple yet efficient fully digital scheme based on dominant eigen-mode transmission (DET) and MMSE combining at each Tx and Rx, respectively. This scheme cancels interference at the Rx and is referred to as DET-MMSE in the following.…”

Interference mitigation in mm-wave backhaul networks with limited channel-state information

“…A good overview of the state of the art can be found in [5]. Most beamforming algorithms require channel-state information to cancel the interferences [6]. To measure and to feedback the channel, however, ties up radio resources, which makes channel estimation expensive for large antenna arrays [7].…”