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

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1372
Author(s):  
Randy Verdecia-Peña ◽  
José I. Alonso
Keyword(s):  
Channel Estimation ◽  
Mobile Communications ◽  
Channel Coding ◽  
Transmission Rate ◽  
Least Square ◽  
The Other ◽  
System Throughput ◽  
Amplify And Forward ◽  
Relay Nodes ◽  
Decode And Forward

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.

scholarly journals Performance Analysis of Two-Hop mmWave Relay Nodes over the 5G NR Uplink Signal

2021 ◽  
Vol 11 (13) ◽  
pp. 5828
Author(s):  
Randy Verdecia-Peña ◽  
José I. Alonso
Keyword(s):  
Channel Coding ◽  
Software Defined Radio ◽  
Relay Node ◽  
Least Square ◽  
The Other ◽  
Practical Implementation ◽  
Modulation Scheme ◽  
Amplify And Forward ◽  
Relay Nodes ◽  
Qam Modulation

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.

scholarly journals A Comprehensive Review on Channel Estimation in OFDM System

2019 ◽  
Vol 5 (3) ◽  
pp. 6 ◽  
Author(s):  
Neha Dubey ◽  
Ankit Pandit
Keyword(s):  
Channel Estimation ◽  
Mean Square Error ◽  
Orthogonal Frequency Division Multiplexing ◽  
Transmission Rate ◽  
Minimum Mean Square Error ◽  
Estimation Method ◽  
Least Square ◽  
Estimation Methods ◽  
Mean Square ◽  
Mimo Ofdm

In wireless communication, orthogonal frequency division multiplexing (OFDM) plays a major role because of its high transmission rate. Channel estimation and tracking have many different techniques available in OFDM systems. Among them, the most important techniques are least square (LS) and minimum mean square error (MMSE). In least square channel estimation method, the process is simple but the major drawback is it has very high mean square error. Whereas, the performance of MMSE is superior to LS in low SNR, its main problem is it has high computational complexity. If the error is reduced to a very low value, then an exact signal will be received. In this paper an extensive review on different channel estimation methods used in MIMO-OFDM like pilot based, least square (LS) and minimum mean square error method (MMSE) and least minimum mean square error (LMMSE) methods and also other channel estimation methods used in MIMO-OFDM are discussed.

scholarly journals Channel Estimation in DCT-Based OFDM

2014 ◽  
Vol 2014 ◽  
pp. 1-6
Author(s):  
Yulin Wang ◽  
Gengxin Zhang ◽  
Zhidong Xie ◽  
Jing Hu
Keyword(s):  
Channel Estimation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Multipath Fading ◽  
Wireless Channel ◽  
Least Square ◽  
System Throughput ◽  
Multipath Fading Channel ◽  
Channel Response ◽  
Coherent Demodulation ◽  
And Performance

This paper derives the channel estimation of a discrete cosine transform- (DCT-) based orthogonal frequency-division multiplexing (OFDM) system over a frequency-selective multipath fading channel. Channel estimation has been proved to improve system throughput and performance by allowing for coherent demodulation. Pilot-aided methods are traditionally used to learn the channel response. Least square (LS) and mean square error estimators (MMSE) are investigated. We also study a compressed sensing (CS) based channel estimation, which takes the sparse property of wireless channel into account. Simulation results have shown that the CS based channel estimation is expected to have better performance than LS. However MMSE can achieve optimal performance because of prior knowledge of the channel statistic.

scholarly journals Individual Channel Estimation in a Diamond Relay Network Using Relay-Assisted Training

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Xianwen He ◽  
Gaoqi Dou ◽  
Jun Gao
Keyword(s):  
Channel Estimation ◽  
Relay Node ◽  
Spatial Diversity ◽  
Relay Network ◽  
Destination Node ◽  
Training Design ◽  
Amplify And Forward ◽  
Relay Nodes ◽  
Training Scheme ◽  
Data Signal

We consider the training design and channel estimation in the amplify-and-forward (AF) diamond relay network. Our strategy is to transmit the source training in time-multiplexing (TM) mode while each relay node superimposes its own relay training over the amplified received data signal without bandwidth expansion. The principal challenge is to obtain accurate channel state information (CSI) of second-hop link due to the multiaccess interference (MAI) and cooperative data interference (CDI). To maintain the orthogonality between data and training, a modified relay-assisted training scheme is proposed to migrate the CDI, where some of the cooperative data at the relay are discarded to accommodate relay training. Meanwhile, a couple of optimal zero-correlation zone (ZCZ) relay-assisted sequences are designed to avoid MAI. At the destination node, the received signals from the two relay nodes are combined to achieve spatial diversity and enhanced data reliability. The simulation results are presented to validate the performance of the proposed schemes.

scholarly journals Hybrid AF/DF Cooperative Relaying Technique with Phase Steering for Industrial IoT Networks

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 937
Author(s):  
Sangku Lee ◽  
Janghyuk Youn ◽  
Bang Chul Jung
Keyword(s):  
Spectrum Sharing ◽  
Low Cost ◽  
Relay Node ◽  
Access Point ◽  
Radio Spectrum ◽  
Cooperative Relaying ◽  
Amplify And Forward ◽  
Relay Nodes ◽  
Decode And Forward ◽  
Industrial Iot

For the next generation of manufacturing, the industrial internet of things (IoT) has been considered as a key technology that enables smart factories, in which sensors transfer measured data, actuators are controlled, and systems are connected wirelessly. In particular, the wireless sensor network (WSN) needs to operate with low cost, low power (energy), and narrow spectrum, which are the most technical challenges for industrial IoT networks. In general, a relay-assisted communication network has been known to overcome scarce energy problems, and a spectrum-sharing technique has been considered as a promising technique for the radio spectrum shortage problem. In this paper, we propose a phase steering based hybrid cooperative relaying (PSHCR) technique for the generic relay-assisted spectrum-shared WSN, which consists of a secondary transmitter, multiple secondary relays (SRs), a secondary access point, and multiple primary access points. Basically, SRs in the proposed PSHCR technique operate with decode-and-forward (DF) relaying protocol, but it does not abandon the SRs that failed in decoding at the first hop. Instead, the SRs operate with amplify-and-forward (AF) protocol when they failed in decoding at the first hop. Furthermore, the SRs (regardless of operating with AF or DF protocol) that satisfy interference constraints to the primary network are allowed to transmit a signal to the secondary access point at the second hop. Note that phase distortion is compensated through phase steering operation at each relay node before second-hop transmission, and thus all relay nodes can operate in a fully distributed manner. Finally, we validate that the proposed PSHCR technique significantly outperforms the existing best single relay selection (BSR) technique and cooperative phase steering (CPS) technique in terms of outage performance via extensive computer simulations.

scholarly journals A Comparative Experimental Study of MIMO A&F and D&F Relay Nodes Using a Software-Defined Radio Platform

Electronics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 570
Author(s):  
Randy Verdecia-Peña ◽  
José I. Alonso
Keyword(s):  
Channel Coding ◽  
Software Defined Radio ◽  
Software Radio ◽  
Block Codes ◽  
System Throughput ◽  
Maximum Throughput ◽  
Relay Nodes ◽  
Transport Channel ◽  
Core Element ◽  
Shared Channel

The relaying technologies in co-operative systems are considered a core element in actual and future wireless communications, assisting the network by enhancing its reliability and improving its capability through exploiting co-operativity. In this paper, a co-operative system testbed based on Software Defined Radio (SDR) through Universal Software Radio Peripherals (USRPs) and the MATLABTM software is presented. The main novelty in this development of the platform is the implementation of 4G signal features, such as Physical Downlink Shared Channel (PDSCH) and Downlink Shared Channel (DL-SCH) for transport channel coding, which is one of the main contribution of the paper. The developed SDR Multi-Input and Multi-Output (MIMO) co-operative platform is capable of developing prototypes for the Relay Nodes (RNs). More specifically, the Amplify-&-Forward (A&F)—with or without Zero Forcing (ZF) and Mean Maximum Square Error (MMSE) Pre-Equalization—and Decode-&-Forward (D&F) protocols were implemented. Both Single-Input and Single-Output (SISO) and MIMO modes are supported by our testbed. The developed A&F and D&F MIMO co-operative systems in this paper utilize Orthogonal Space-Frequency Block Codes (OSFBCs) for the transmission of data symbols from the source to the destination. Our results show that RNs can substantially improve the Bit Error Rate (BER) and throughput in communications between the eNodeB and User Equipment (UE). In particular, the maximum throughput achieved by conventional MIMO A&F is 9.3Mbps at Signal-to-NoiseRatio(SNR)=16dB, which is 4Mbps higher than throughput of MIMO Non-Co-operative. It also shows the capacity improvement when considering the pre-equalization in the A&F schemes, compared to the conventional A&F RN. For example, with MIMO A&F-MMSE pattern, a value os 11.8 Mbps is achieved for SNR=16dB, which is 84.8% of the maximum system throughput (13.95 Mbps). On the other hand, the obtained results with D&F schemes far exceed those obtained with A&F strategies, achieving the maximum performance with the 2×2 MIMO D&F protocol from SNR=8dB.Furthermore, this work constitutes a first stage to the implementation of a 5G New-Radio Co-operative System platform.

scholarly journals Performance Evaluation of OFDM System using Pseudo-Pilots with Particle Swarm & Moth Flame (Hybrid) Optimization

2019 ◽  
Vol 8 (9S) ◽  
pp. 127-130
Keyword(s):  
Channel Estimation ◽  
Orthogonal Frequency Division Multiplexing ◽  
Transmission Rate ◽  
Signal To Noise Ratio ◽  
Particle Swarm ◽  
Least Square ◽  
Coherent Detection ◽  
Receiver Design ◽  
Recursive Least Square ◽  
High Data

This paper is focused on the advanced signal processing techniques for the multi-carrier modulation especially on the orthogonal frequency division multiplexing (OFDM). OFDM has high data rate and robust against the frequency selective multi-path channels. Channel estimation is crucial for the receiver design in coherent detection. In this paper we are investigating and examining the pilot aided system for channel estimation and its special effects on the performance of the OFDM based system. In this paper new technique is proposed which make use of conventional Least Square (LS) and Recursive Least Square (RLS) hybridization techniques for the channel estimation afterwards we apply Particle Swarm Optimization (PSO) and Hybrid PSO (PSO+ Moth Flame Optimization(MFO)) optimization for obtaining more optimize techniques. In the proposed system, to estimate channel impulse response we are using pseudo-pilots instead to pilots as it is useful to overcome the pilot overhead and decrease the complexity by using pseudo random symbol (PRS). The performance of the proposed techniques and the weighted scheme are compared and verified using computerized simulation carried out using Matrix Laboratory (MATLAB) software. It is demonstrated on the basis of graph between BER and signal to Noise Ratio (Eb/NO), that the proposed technique reduces the execution time and increase the transmission rate with low or zero overhead.

scholarly journals On the Coverage Extension and Capacity Enhancement of Inband Relay Deployments in LTE-Advanced Networks

2010 ◽  
Vol 2010 ◽  
pp. 1-12 ◽  
Author(s):  
Abdallah Bou Saleh ◽  
Simone Redana ◽  
Jyri Hämäläinen ◽  
Bernhard Raaf
Keyword(s):  
Relay Node ◽  
System Capacity ◽  
System Level ◽  
System Throughput ◽  
Relay Nodes ◽  
Decode And Forward ◽  
Radio Access ◽  
Lte Advanced ◽  
Coverage Extension

Decode-and-forward relaying is a promising enhancement to existing radio access networks and is currently being standardized in 3GPP to be part of the LTE-Advanced release 10. Two inband operation modes of relay nodes are to be supported, namely Type 1 and Type 1b. Relay nodes promise to offer considerable gain for system capacity or coverage depending on the deployment prioritization. However, the performance of relays, as any other radio access point, significantly depends on the propagation characteristics of the deployment environment. Hence, in this paper, we investigate the performance of Type 1 and Type 1b inband relaying within the LTE-Advanced framework in different propagation scenarios in terms of both coverage extension capabilities and capacity enhancements. A comparison between Type 1 and Type 1b relay nodes is as well presented to study the effect of the relaying overhead on the system performance in inband relay node deployments. System level simulations show that Type 1 and Type 1b inband relay deployments offer low to very high gains depending on the deployment environment. As well, it is shown that the effect of the relaying overhead is minimal on coverage extension whereas it is more evident on system throughput.

scholarly journals HD/FD and DF/AF with Fixed-Gain or Variable-Gain Protocol Switching Mechanism over Cooperative NOMA for Green-Wireless Networks

Sensors ◽  
2019 ◽  
Vol 19 (8) ◽  
pp. 1845 ◽  
Author(s):  
Thanh-Nam Tran ◽  
Miroslav Voznak
Keyword(s):  
Wireless Networks ◽  
Full Duplex ◽  
System Throughput ◽  
Amplify And Forward ◽  
Decode And Forward ◽  
Variable Gain ◽  
Switching Mechanism ◽  
Half Duplex ◽  
Protocol Switching

This article studied the application of multiple protocol switching mechanism (PSM) over cooperating Non-Orthogonal Multiple Access (NOMA) networks to minimize the probability of outage and maximize the system throughput and energy efficiency (EE). This study investigated six scenarios: (1) a cooperative NOMA system with half-duplex (HD) and decode-and-forward (DF) protocols at the relay; (2) a cooperative NOMA system with full-duplex (FD) and DF protocols at the relay; (3) a cooperative NOMA system with HD and amplification amplify-and-forward (AF) with fixed-gain (FG) protocols at the relay; (4) a cooperative NOMA system with HD and amplification AF with variable-gain (VG) protocols at the relay; (5) a cooperative NOMA system with FD and amplification AF with FG protocols at the relay; (6) a cooperative NOMA system with FD and amplification AF with VG protocols at the relay. Based on the results of analysis and simulations, the study determined the transmission scenario for best system performance. This paper also proposed a mechanism to switch between HD/FD and DF/AF with FG/VG protocols in order to improve the quality of service (QoS) for users with a weak conditional channel. This mechanism can be deployed in future 5G wireless network sensors. Finally, EE was also assessed in relation to future green-wireless networks (G-WNs).

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