scholarly journals Investigation on Mutual Contention Bandwidth Request Mechanisms in Two-Hop Relay Network with ITU-R Path Loss Models

2013 ◽  
Vol 2013 ◽  
pp. 1-13
Author(s):  
Rajesh Anbazhagan ◽  
Nakkeeran Rangaswamy
Keyword(s):  
Path Loss ◽  
Contention Window ◽  
Relay Network ◽  
Failure Model ◽  
Bandwidth Request ◽  
Channel Error ◽  
Mobile Stations ◽  
Failure Models ◽  
Loss Models ◽  
Transmission Failures

The performance of two-hop contention based bandwidth request (BR) mechanism for WiMAX relay networks is investigated under ITU-R path loss models. In conventional WiMAX systems, the mobile stations (MS) update their contention window irrespective of their transmission failures. Those systems update their contention window on collision and due to channel error or unavailability of bandwidth. Further, these failure models have been suggested for single hop networks. The failure model in two-hop systems becomes complex since it may include additional failure events such as improper detection of codes and channel error due to varying path loss. Interestingly, these failure events (collision, channel error, unavailability of bandwidth, and improper detection of codes) do not occur evenly for both hops of a link. Hence, to set the contention window effectively, unique failure models are developed by considering the characteristics of BR mechanism and hop at which the BR is performed. In the proposed system, the two-hop BR is carried out with all combinations of message and code bandwidth request schemes. Among them, the message-code BR mechanism performs better under suburban fixed and outdoor to indoor or pedestrian environment, and code-code BR scheme performs better for vehicular environment.

scholarly journals Path loss models based on stochastic rays

2007 ◽  
Vol 1 (3) ◽  
pp. 602 ◽  
Author(s):  
L.Q. Hu ◽  
H. Yu ◽  
Y. Chen
Keyword(s):  
Path Loss ◽  
Loss Models

scholarly journals Bounding the Practical Error of Path Loss Models

2012 ◽  
Vol 2012 ◽  
pp. 1-21 ◽  
Author(s):  
Caleb Phillips ◽  
Douglas Sicker ◽  
Dirk Grunwald
Keyword(s):  
A Priori ◽  
Path Loss ◽  
Urban Environments ◽  
Production Networks ◽  
Modeling Error ◽  
Propagation Models ◽  
Performance Accuracy ◽  
Rural And Urban ◽  
Standard Models ◽  
Loss Models

We seek to provide practical lower bounds on the prediction accuracy of path loss models. We describe and implement 30 propagation models of varying popularity that have been proposed over the last 70 years. Our analysis is performed using a large corpus of measurements collected on production networks operating in the 2.4 GHz ISM, 5.8 GHz UNII, and 900 MHz ISM bands in a diverse set of rural and urban environments. We find that the landscape of path loss models is precarious: typical best-case performance accuracy of these models is on the order of 12–15 dB root mean square error (RMSE) and in practice it can be much worse. Models that can be tuned with measurements and explicit data fitting approaches enable a reduction in RMSE to 8-9 dB. These bounds on modeling error appear to be relatively constant, even in differing environments and at differing frequencies. Based on our findings, we recommend the use of a few well-accepted and well-performing standard models in scenarios wherea prioripredictions are needed and argue for the use of well-validated, measurement-driven methods whenever possible.

Empirical Path-loss Models for Automated Warehouses

2021 ◽  
Author(s):  
Ognen Ognenoski ◽  
Di Kong ◽  
Boyan Ivanov ◽  
Yu An ◽  
Adam Green
Keyword(s):  
Path Loss ◽  
Automated Warehouses ◽  
Loss Models
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