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In this paper, the uplink in a two-hop 5G new radio co-operative system using Relay Nodes (RNs) in millimeter bands has been simulated and studied. We focus on an uplink Amplify-and-Forward Relay Node (A&F RN) and Decode-and-Forward Relay Node (D&F RN) with an mmWave-band transceiver chain (Tx/Rx). We study two uplink mmWave MIMO D&F relaying protocols assuming, firstly, the complete knowledge of the uplink channel and, secondly, the uplink channel estimation through a Least Square (LS) algorithm. To verify the benefits of the proposed uplink mmWave MIMO co-operative network, a link-level co-operative simulator has been developed using MatlabTM and SimulinkTM software, where an indoor-to-outdoor scenario and mmWave transceiver with off-the shelf components are considered. The main novelty of this link-level co-operative simulator and the implemented relay nodes is the usage of signals with 5G NR features, such as UL-SCH transport channel coding and PUSCH generation, which are the other main contributions of this article. Based on the numerical results in terms of the achievable Bit Error Rate (BER) and throughput, we show that the two-hop uplink co-operative network substantially improves the performance in the communications between the NR-User Equipment (NR-UE) and the logical 5G Radio Node (gNodeB). For example, the results from using uplink mmWave NR-D&F protocols far exceed those achieved with the uplink mmWave NR-A&F algorithm; in the case of the 64-QAM modulation scheme for the SISO technique, an improvement of 6.5 Mbps was achieved using the D&F PCE protocol, taking into account that the 256-QAM constellation is higher by 4.05 Mbps. On the other hand, an average throughput enhancement of 28.77 Mbps was achieved when an uplink mmWave (2 × 4 × 4) D&F PCE strategy was used versus an uplink mmWave SISO D&F LS protocol for a Signal-to-Noise Ratio (SNR) = 20 dB and 64-QAM signal. However, an improvement of 56.42 Mbps was reached when a 256-QAM modulation scheme was employed. Furthermore, this paper introduces the first study to develop an uplink mmWave MIMO 5G co-operative network platform through a Software Defined Radio (SDR) from a practical implementation point of view. |
