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

Abstract

Millimeter-Wave (mmWave) bands are receiving enormous attention in 5G mobile communications, due to the capability to provide a multi-gigabit transmission rate. In this paper, a two-hop architecture for 5G communications with the capacity to support high end-to-end performance due to the use of Relay Nodes (RNs) in mmWave-bands is presented. One of the novelties of the paper is the implementation of Amplify-and-Forward (A&F) and Decode-and-Forward (D&F) RNs along with a mmWave-band transceiver chain (Tx/Rx). In addition, two approaches for channel estimation were implemented at the D&F RN for decoding the backhaul link. One of them assumes complete knowledge of the channel (PCE), and the other one performs the channel estimation through Least Square (LS) estimator. A large number of simulations, using MATLABTM and SimulinkTM software, were performed to verify the potential benefits of the proposal two-hop 5G architecture in an outdoor-to-indoor scenario. The main novelty in performing these simulations is the use of signals with 5G features, as DL-SCH transport channel coding, PDSCH generation, and SS Burst generation, which is another of the main contributions of the paper. On the other hand, mmWave transmitter and receiver chains were designed and implemented with off-the shelf components. The simulations show that the two-hop network substantially improves the Key Performance Indicators (KPIs), Bit Error Rate (BER), and Throughput, in the communications between the logical 5G Radio Node (gNodeB), and the New Radio User Equipment (NR-UE). For example, a throughput improvement of 22 Mbps is obtained when a 4 × 4 × 2 MIMO D&F with LS architecture is used versus a SISO D&F with PCE architecture for Signal-to-Noise Ratio (SNR) = 20 dB and 64-QAM signal. This improvement reaches 96 Mbps if a 256-QAM signal is considered. The improvement in BER is 11 dB and 10.5 dB, respectively, for both cases. This work also shows that the obtained results with D&F RNs are better than with A&F RNs. For example, an improvement of 17 Mbps in the use of SISO D&F with LS vs. SISO A&F, for the 64-QAM signal is obtained. Besides, this paper constitutes a first step to the implementation of a mmWave MIMO 5G cooperative network platform.

Design and Synchronization Procedures of a D&F Co-Operative 5G Network Based on SDR Hardware Interface: Performance Analysis

“…The presented results show the advantages of inserting D&F relay node in 5G mobile networks. Furthermore, it should be noted that in the case of mmWave communications, the use of relay nodes will be more necessary, as demonstrated in [30,31]. Future research work includes the development and implementation of algorithms for the uplink of the 5G signal.…”

“…Recently, refs. [30,31] designed and implemented a link-level out-of-band co-operative network simulator for the study of mmWave MIMO RN over downlink and uplink 5G signals, respectively. However, the real implementation of the co-operative network over 5G signal has not been deeply approached in literature yet.…”

Advanced Physical-Layer Technologies for Beyond 5G Wireless Communication Networks

“…MIMO is envisaged as a key enabling technology for 5G networks [ 27 ]. In the paper titled A Two-Hop mmWave MIMO NR-Relay Nodes to Enhance the Average System Throughput and BER in Outdoor-to-Indoor Environments [ 28 ], the authors presented the architecture of two-hop out-of-band relay nodes (RNs) with MIMO capabilities to enable 5G communications in the mmWave band. Two relaying strategies, i.e., amplify-and-forward and decode-and-forward, were implemented to assist communications in outdoor-to-indoor environments between 5G radio node and NR user equipment.…”