COOPERATIVE RELAY PROTOTYPE DEVELOPMENT AND PERFORMANCE MEASUREMENT

2015 ◽  
Vol 77 (10) ◽  
Author(s):  
Igbafe Orikumhi ◽  
Muhammad Rushidi Sabirin ◽  
Chee Yen Leow
Keyword(s):  
Power Efficiency ◽  
System Development ◽  
Software Radio ◽  
Path Loss ◽  
Multipath Fading ◽  
Cooperative Relaying ◽  
Cooperative Relay ◽  
Communication Link ◽  
Amplify And Forward ◽  
Prototype Development

To meet the demand for high data rate, the wireless cellular system technology has grown in a steady pace in recent years. However, due to multipath fading, shadowing effects and path loss, the wireless communication links are prone to errors. To improve the communication link, at the cell edge and shadowed environment, cooperative relaying scheme has been proposed. In cooperative relaying, an additional node is placed between the source and destination terminals, to provide redundant path for data transmission. However, existing literature on cooperative relaying only investigates the system performance through theoretical simulations. The real world performance remains unknown because of the lack of prototypes for field testing and measurement. This work focuses on the development of an amplify-and-forward (AF) cooperative relaying prototype. The prototype is developed using the LabVIEW system development platform and the implementations are carried out on Universal Software Radio Peripheral (USRP). The performance of the AF based cooperative relaying prototype is measured in terms of the bit error rate (BER) and compared with the direct communication link without relay. The measured results show that cooperative relay assisted communication achieves significant improvement in terms of signal reliability, coverage distance and power efficiency.

Cross–Layer Relay Selection For Cooperative Relay System In IEEE 802.16j Network

2012 ◽  
Author(s):  
Anis Izzati Ahmad Zamani ◽  
Nurul Nazirah Mohd Imam Ma’AROF ◽  
Farah Buthainah Nor Yusof ◽  
Nurulashikin Satiman ◽  
Sharifah Kamilah Syed Yusof ◽  
...  
Keyword(s):  
Relay Selection ◽  
Base Station ◽  
Cooperative Relaying ◽  
Cooperative Relay ◽  
Cross Layer ◽  
Communication Link ◽  
Mac Layer ◽  
Relay System ◽  
Selection Scheme ◽  
Ieee 802.16J

The IEEE 802.16j amendment has been developed to improve the performance of the IEEE 802.16e standard in terms of its network capacity and coverage area via employment of relay stations. An optional feature of cooperative relay has been initiated to fully utilize multihop network environment. This work focuses on the selection of cooperative relay path/paths through cross–layer approach to forward data from source to destination. The selection scheme jointly considers the signal–to–noise ratio (SNR) from physical (PHY) layer and buffer status from medium access control (MAC) layer. The SNR of the communication link between the base–station and the mobile station has to be compared to a certain threshold before making decision on the optimal cooperative relaying mode. Numerical and simulation results show that cooperative relaying improves the throughput and delay of the IEEE 802.16j system. In addition, the average transmission time of cooperative relay system decreases when the parameter from the MAC layer is considered in the relay selection scheme. Key words: Cooperative relay, IEEE 802.16j, relay selection, cross–layer design

Performance evaluation of AF-relayed mixed FSO/mm-wave-RF link modeled by generalized misalignment and RF fading distributions

Frequenz ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Himanshu Khanna
Keyword(s):  
Wireless Channels ◽  
Path Loss ◽  
Multipath Fading ◽  
Cumulative Distribution ◽  
60 Ghz ◽  
Free Space Optical ◽  
Amplify And Forward ◽  
Error Performance ◽  
Multiuser Transmission ◽  
Vertical Displacements

AbstractThe performance of a generalized mixed free-space-optical (FSO)/millimeter (mm)-wave radio-frequency (RF) two-hop link model is investigated in this work. The first-hop FSO channel considers the influence of path loss, atmospheric turbulence which is modeled by the gamma–gamma (GG)-distribution, and generalized misalignment errors which incorporate the effects of non-zero boresight errors, different jitter standard deviations along the horizontal and vertical directions, and correlation between the horizontal and vertical displacements. The second-hop RF link is modeled by an extended-generalized-K (EGK) distribution which is a versatile distribution and can characterize various fading conditions in mm-wave wireless channels where the transmission frequency is in excess of 60 GHz, and considers non-homogeneous propagation, interference effects due to multiuser transmission, multipath fading and shadowing effects observed in mm-wave RF wireless channels. The considered system employs fixed-gain amplify-and-forward (AF) relay-assisted transmission. The statistical characteristic for the end-to-end SNR, i.e., cumulative distribution function (cdf), is obtained for the considered system model in this work. Based on the obtained result for cdf, the outage and error performance is evaluated, and closed form expressions for the same are derived. The derived analytical results have been illustrated through numerical plots.

scholarly journals NLOS Path Loss Model for Low-Height Antenna Links in High-Rise Urban Street Grid Environments

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Juyul Lee ◽  
Myung-Don Kim ◽  
Hyun Kyu Chung ◽  
Jinup Kim
Keyword(s):  
Path Loss ◽  
Field Measurements ◽  
Propagation Path ◽  
Delay Spread ◽  
Communication Link ◽  
Channel Measurements ◽  
Loss Model ◽  
Path Loss Model ◽  
Power Delay Profile ◽  
High Rise

This paper presents a NLOS (non-line-of-sight) path loss model for low-height antenna links in rectangular street grids to account for typical D2D (device-to-device) communication link situations in high-rise urban outdoor environments. From wideband propagation channel measurements collected in Seoul City at 3.7 GHz, we observed distinctive power delay profile behaviors between 1-Turn and 2-Turn NLOS links: the 2-Turn NLOS has a wider delay spread. This can be explained by employing the idea that the 2-Turn NLOS has multiple propagation paths along the various street roads from TX to RX, whereas the 1-Turn NLOS has a single dominant propagation path from TX to RX. Considering this, we develop a path loss model encompassing 1-Turn and 2-Turn NLOS links with separate scattering and diffraction parameters for the first and the second corners, based on the Uniform Geometrical Theory of Diffraction. In addition, we consider the effect of building heights on path loss by incorporating an adjustable “waveguide effect” parameter; that is, higher building alleys provide better propagation environments. When compared with field measurements, the predictions are in agreement.

scholarly journals Analysis of transmission characteristics of non-line-of-sight ultraviolet light under complex channel conditions

2021 ◽  
Vol 336 ◽  
pp. 01012
Author(s):  
Xuan Zheng ◽  
Yanfeng Tang ◽  
Jingyi Du
Keyword(s):  
Ultraviolet Light ◽  
Path Loss ◽  
Mie Scattering ◽  
Spherical Particles ◽  
Dust Particles ◽  
Line Of Sight ◽  
Communication Link ◽  
Communication Quality ◽  
Long Distance ◽  
Non Line Of Sight

Using the multiple scattering model of non-line-of-sight ultraviolet light to simulate and analyze the atmospheric channel characteristics in the complex environment of haze and dust. The Mie scattering theory and T matrix method are used to analyze the path loss of spherical particles and non-spherical particles with particle concentration at different communication distances. The results show that when the communication distance is less than 50 meters, the communication quality under severe haze is the best, and for long-distance communication, the path loss under severe haze increases almost proportionally. In the non-line-of-sight ultraviolet light communication link, the higher the concentration of dust particles, the better the communication quality of the non-line-of-sight ultraviolet light communication transmission. Analysis of the scattering coefficient of spherical particles is significantly greater than that of non-spherical particles.

scholarly journals Linear Multi-hop Amplify-and-Forward (AF) Cooperative Relay Channels

10.7125/40.10 ◽  
2015 ◽  
Vol 40 (0) ◽  
pp. 64 ◽  
Author(s):  
Li Suet Mok ◽  
Chee Kyun Ng ◽  
Nor Kamariah Noordin
Keyword(s):  
Cooperative Relay ◽  
Relay Channels ◽  
Amplify And Forward

Modified genetic algorithm based power allocation scheme for amplify-and-forward cooperative relay network

2018 ◽  
Vol 69 ◽  
pp. 628-641 ◽  
Author(s):  
Anand Gachhadar ◽  
MHD Nour Hindia ◽  
Faizan Qamar ◽  
M. Hassam Shakil Siddiqui ◽  
Kamarul Ariffin Noordin ◽  
...  
Keyword(s):  
Genetic Algorithm ◽  
Power Allocation ◽  
Relay Network ◽  
Cooperative Relay ◽  
Allocation Scheme ◽  
Amplify And Forward ◽  
Modified Genetic Algorithm ◽  
Cooperative Relay Network

Improving the Performance of HALE UAV Communication Link Through MIMO Cooperative Relay Strategy

2020 ◽  
Vol 113 (2) ◽  
pp. 1051-1071
Author(s):  
Mohammadreza Tarihi ◽  
Mohammad Mahdinejad Noori ◽  
Mohammadhossein Madani
Keyword(s):  
Cooperative Relay ◽  
Communication Link

Review of LiFi Technology and Its Future Applications

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Safwan Alfattani
Keyword(s):  
Traffic Management ◽  
Path Loss ◽  
Hard Core ◽  
Cost Effective ◽  
Multipath Fading ◽  
Radio Spectrum ◽  
Hybrid Technique ◽  
Light Spectrum ◽  
Rf Systems ◽  
High Data

AbstractIn order to respond to the increasing demand of capacity and bandwidth caused by the high number of wireless applications and users, LiFi technology was introduced. It uses the visible light spectrum instead of the radio spectrum to transmit data wirelessly through the illumination of LED lamps. The main advantage of this technology is to provide wireless communications with high data rates. Other advantages include efficiency, availability, security and safety. Also, this technology uses free unlicensed spectrum, and it is cost-effective. Additionally, unlike RF systems, no multipath fading and the transmitter and receiver circuits are not complex. However, LiFi has several issues, which include high path loss, sensitivity to blockages and Non-line-of-sight (NLOS) situations. Probably, the biggest issue of LiFi is the uplink communication which is difficult to implement due to practical and cost reasons. Several future applications of this technology include places where RF is restricted such as hospitals and airplanes. Also, it can be used for traffic management, underwater communication, and outdoor access to the Internet. Moreover, it can be combined with WiFi technology either in hybrid technique or aggregated technique. It is found that later technique gives better results. Another possible application is the optical attocells. It is found that the hexagonal cells model is the best for deterministic deployments of optical APs, whereas the hard-core point process (HCPP) model is the best for random deployments. Furthermore, LiFi can be used for multiuser access with high data rate by using non-orthogonal multiple access (NOMA) technique. Due to the great features of LiFi, more applications and everyday life devices will adopt this technology in the future. However, Because of its limitations, it may not totally replace RF technology, but they will work collaboratively to achieve a better performance.

scholarly journals LOS-Based Equal Gain Transmission and Combining in General Frequency-Selective Ricean Massive MIMO Channels

Electronics ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 79 ◽  
Author(s):  
Qiuna Yan ◽  
Yu Sun ◽  
Dian-Wu Yue
Keyword(s):  
Spatial Correlation ◽  
Scaling Laws ◽  
Mimo System ◽  
Cooperative Relaying ◽  
Power Scaling ◽  
Hardware Complexity ◽  
Amplify And Forward ◽  
Decode And Forward ◽  
Frequency Selective ◽  
General Frequency

In general frequency-selective Ricean fading environments with doubly-ended spatial correlation, this paper investigates the spectral efficiency of a broadband massive multiple-input multiple-output (MIMO) system. In particular, in order to reduce overhead of channel estimation effectively, it proposes a scheme of equal gain transmission and combining, which is only based on line- of-sight (LOS) component and has low hardware complexity. With the scheme, several interesting transmit power scaling properties without and with spatial correlation are derived when the number of antennas at the transmitter or the number of antennas at the receiver grows in an unlimited way. Furthermore, the asymptotical rate analysis is extended to the cooperative relaying scenarios with decode-and-forward and amplify-and-forward protocols, respectively, and then two novel power scaling laws are given.

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