143 research outputs found
Low complexity hybrid precoding designs for multiuser mmWave/THz ultra massive MIMO Systems
Millimeter-wave and terahertz technologies have been attracting attention from the wireless research community since they can offer large underutilized bandwidths which can enable the support of ultra-high-speed connections in future wireless communication systems. While the high signal attenuation occurring at these frequencies requires the adoption of very large (or the so-called ultra-massive) antenna arrays, in order to accomplish low complexity and low power consumption, hybrid analog/digital designs must be adopted. In this paper we present a hybrid design algorithm suitable for both mmWave and THz multiuser multiple-input multiple-output (MIMO) systems, which comprises separate computation steps for the digital precoder, analog precoder and multiuser interference mitigation. The design can also incorporate different analog architectures such as phase shifters, switches and inverters, antenna selection and so on. Furthermore, it is also applicable for different structures, namely fully-connected structures, arrays of subarrays (AoSA) and dynamic arrays of subarrays (DAoSA), making it suitable for the support of ultra-massive MIMO (UM-MIMO) in severely hardware constrained THz systems. We will show that, by using the proposed approach, it is possible to achieve good trade-offs between spectral efficiency and simplified implementation, even as the number of users and data streams increases.info:eu-repo/semantics/publishedVersio
Design of Full-Duplex Millimeter-Wave Integrated Access and Backhaul Networks
One of the key technologies for the future cellular networks is full duplex
(FD)-enabled integrated access and backhaul (IAB) networks operating in the
millimeter-wave (mmWave) frequencies. The main challenge in realizing FD-IAB
networks is mitigating the impact of self-interference (SI) in the wideband
mmWave frequencies. In this article, we first introduce the 3GPP IAB network
architectures and wideband mmWave channel models. By utilizing the
subarray-based hybrid precoding scheme at the FD-IAB node, multiuser
interference is mitigated using zero-forcing at the transmitter, whereas the
residual SI after successfully deploying antenna and analog cancellation is
canceled by a minimum mean square error baseband combiner at the receiver. The
spectral efficiency (SE) is evaluated for the RF insertion loss (RFIL) with
different kinds of phase shifters and channel uncertainty. Simulation results
show that, in the presence of the RFIL, the almost double SE, which is close to
that obtained from fully connected hybrid precoding, can be achieved as
compared to half duplex systems when the uncertainties are of low strength
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