Separable MSE-Based Design of Two-Way Multiple-Relay Cooperative MIMO 5G Networks

Abstract

While the combination of multi-antenna and relaying techniques has been extensively studied for Long Term Evolution Advanced (LTE-A) and Internet of Things (IoT) applications, it is expected to still play an important role in 5th Generation (5G) networks. However, the expected benefits of these technologies cannot be achieved without a proper system design. In this paper, we consider the problem of jointly optimizing terminal precoders/decoders and relay forwarding matrices on the basis of the sum mean square error (MSE) criterion in multiple-input multiple-output (MIMO) two-way relay systems, where two multi-antenna nodes mutually exchange information via multi-antenna amplify-and-forward relays. This problem is nonconvex and a local optimal solution is typically found by using iterative algorithms based on alternating optimization. We show how the constrained minimization of the sum-MSE can be relaxed to obtain two separated subproblems which, under mild conditions, admit a closed-form solution. Compared to iterative approaches, the proposed design is more suited to be integrated in 5G networks, since it is computationally more convenient and its performance exhibits a better scaling in the number of relays.

A Two-Hop mmWave MIMO NR-Relay Nodes to Enhance the Average System Throughput and BER in Outdoor-to-Indoor Environments

“…In this subsection, the presented architecture is compared with previous works evaluating similar architectures [ 34 , 35 , 36 , 37 ], in terms of the type of implemented RNs in the architecture, the working frequency of the backhaul and access links, and if the architecture under analysis was implemented by hardware, as shown in Table 4 . In general, in these works, the operation of the A&F and D&F protocols were analyzed and compared, showing that the use of D&F RNs presents an improvement in the performance of the architecture compared to A&F RNs.…”

“…This paper also proposes a hardware implementation of the relay nodes through the design of mmWave transmitter and receiver chains with off-the shelf, having considered in the simulations the non-linearities of the used subsystems. On the other hand, our proposal has the disadvantage of working in Half Duplex mode, compared to the Full Duplex operation of the other architectures considered [ 34 , 35 , 36 , 37 ], which will be addressed in further research.…”

Impacts of interpersonal distancing on-board trains during the COVID-19 emergency

“…Alternative actions that could be implemented to mitigate crowding are: The introduction of advanced traveler’s information systems to monitor in real time trains/stations inflows and outflows, and to inform travelers about possible service unavailability or presence of queues due to overcrowding, using both electronic displays installed at bus stops / stations and mobile travel apps (see, for instance, [ 9 ]); The introduction of seat reservation systems to access trains and/or stations, similar to those for ex-urban services. …”

“…The introduction of advanced traveler’s information systems to monitor in real time trains/stations inflows and outflows, and to inform travelers about possible service unavailability or presence of queues due to overcrowding, using both electronic displays installed at bus stops / stations and mobile travel apps (see, for instance, [ 9 ]);…”

Adaptive Relay Selection Scheme by Using Compound Channel

“…For same data rate, two-way relaying protocol improves transmission power consumption and spectral than one-way relaying protocol [8]. For this reason, two way relaying protocols have been studied actively to improve performance [9,10]. The relay can be used to decentralize the overload of cell nodes in a heterogeneous UDN system [11].…”