scholarly journals An Improved Backoff Scheme and Its Performance Analysis for Full Duplex MAC Protocols in VLC Networks

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8263
Author(s):  
Yuta Sawa ◽  
Kosuke Sanada ◽  
Hiroyuki Hatano ◽  
Kazuo Mori
Keyword(s):  
Performance Analysis ◽  
Markov Chain Model ◽  
Visible Light Communication ◽  
Packet Transmission ◽  
Data Packet ◽  
Performance Evaluations ◽  
Full Duplex ◽  
Chain Model ◽  
Transmission Technique ◽  
Directional Transmission

IEEE 802.15.7 Visible Light Communication (VLC) networks suffer from performance degradation caused by the hidden device collisions due to the directional transmission with narrow beamwidth. One of the solutions for mitigating the hidden device collisions is to employ a full-duplex transmission technique. As a side effect of the full-duplex transmission in the VLC networks, however, the data-packet discard due to the retransmission limitation occurs frequently in the networks. This paper proposes an improved backoff scheme and its performance analysis to suppress the packet discard. The proposed backoff scheme increases the Backoff Exponent (BE) and the Number of Backoff stage (NB) in IEEE 802.15.7 only when the data packet transmission fails. To evaluate the system performance theoretically, this paper also provides the Markov-chain model for channel access with the proposed scheme. The performance evaluations through simulation and theoretical analysis show the effectiveness of the proposed scheme.

scholarly journals Performance Analysis on Transfer Platforms in Frame Bridge Based Automated Container Terminals

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Hongtao Hu ◽  
Byung Kwon Lee ◽  
Youfang Huang ◽  
Loo Hay Lee ◽  
Ek Peng Chew
Keyword(s):  
Markov Chain ◽  
Performance Analysis ◽  
Markov Chain Model ◽  
Container Terminal ◽  
Container Terminals ◽  
Automated Guided Vehicles ◽  
Chain Model ◽  
Quay Cranes ◽  
Automated Container Terminal ◽  
Multistory Frame

This paper studies a new automated container terminal (ACT) system which utilizes multistory frame bridges and rail-mounted trolleys to transport containers between the quay and the yard. Beside typical ACT systems use trucks or automated guided vehicles for transporting containers between quay cranes and yard cranes, the new design uses three types of handling machines, namely, ground trolleys (GTs), transfer platforms (TPs), and frame trolleys (FTs). These three types of handling machines collaborate with one another to transport containers. This study decomposes the system into several subsystems. Each subsystem has one TP and several FTs and GTs dedicated to this TP. Then, a Markov chain model is developed to analyze the throughput of TPs. At last, the performance of the new ACT system is estimated. Sensitivity analyzes the numbers, and the processing rates of trolleys are conducted through the numeric experiments.

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