scholarly journals The analysis of IEEE 802.11 PCF protocol based on LEO satellite Wi-Fi

2018 ◽  
Vol 189 ◽  
pp. 04014
Author(s):  
Wen He ◽  
Xiaofeng Tao ◽  
Defeng Ren
Keyword(s):  
Propagation Delay ◽  
Paper Analysis ◽  
System Throughput ◽  
Matlab Simulation ◽  
802.11 Dcf ◽  
Transmission Distance ◽  
Hidden Terminals ◽  
Original Scheme ◽  
Improvement Scheme ◽  
Leo Satellite

In view of the problem of long propagation delay, hidden terminals and serious user conflicts in LEO satellite Wi-Fi scenario, this paper analysis the incompatibility of 802.11 DCF protocol briefly. A scheme of PCF polling mechanism based on priority is proposed and the frame format is adaptively modified. Through MATLAB simulation, the system throughput of the original scheme and the improvement scheme over the different transmission distance and nodes are analysed. The simulation results show that the improved PCF protocol can improve the throughput under the multi-user over long distances.

The Design of GPS Digital IF Signal Simulator

2012 ◽  
Vol 490-495 ◽  
pp. 1631-1635
Author(s):  
Bei Zhang
Keyword(s):  
Carrier Phase ◽  
Sampling Rate ◽  
Intermediate Frequency ◽  
Propagation Delay ◽  
Ionospheric Model ◽  
Research Development ◽  
Matlab Simulation ◽  
Gps Navigation ◽  
Matlab Implementation ◽  
Gps System

This paper focuses on the study of digital IF signal simulator's Matlab implementation on the basis of GPS system and GPS navigation signal simulator.It includes the simulator's parameter settings (such as the sampling rate,intermediate frequency), then calculates the sampling signal's code phase and carrier phase by determining the signal's propagation delay. In addition,it introduces and simulates the ionospheric model and the tropospheric model,and corrects the sampling signal's code phase and carrier phase.This paper realizes GPS digital IF signal simulator's Matlab simulation,thus it provides the supporting platform for research,development and testing of the GPS receiver's new algorithm

Propagation Delay Characteristics Analysis in LEO Satellite Multi-Beam Antenna Coverage

2013 ◽  
Vol 791-793 ◽  
pp. 1931-1935
Author(s):  
Ming Ma ◽  
Xi Luan ◽  
Bin Li ◽  
Jian Jun Wu
Keyword(s):  
Satellite Communications ◽  
Propagation Delay ◽  
Satellite System ◽  
Calculation Model ◽  
Propagation Delays ◽  
Characteristics Analysis ◽  
Leo Satellite ◽  
Communications System ◽  
Calculated Analysis

In this paper a calculation model of propagation delays of satellite beams is introduced for LEO multi-beam satellite communications system. Based on actual parameters and beam coverage patterns of the Iridium and Globalstar system, the maximum propagation delay differentials in several typical beams from the center to the edge of the satellites coverage are calculated. Analysis of these results can provide reference for analyzing the feasibility of LEO multi-beam satellite system compatible with uplink synchronization in LTE.

ZPW2000 Rail Transmission Network of Compensation Capacitor Analysis and Ponder

2014 ◽  
Vol 494-495 ◽  
pp. 1473-1476
Author(s):  
Bin Huang ◽  
Jian Jun Wu
Keyword(s):  
Paper Analysis ◽  
Experimental Results ◽  
Transmission Network ◽  
Situation Analysis ◽  
Transmission Distance ◽  
Track Circuit ◽  
Research And Design

In order to better research and design track circuit system, this paper analysis and calculated compensation capacitor of the ZPW2000 no insulation track circuit, and verified the consistency of the experimental results and the practical installation situation. Analysis results also show that, through the appropriate compensation capacitor, the no insulation track circuit transmission distance significantly increased.

scholarly journals Modeling and analysis of medium speed maglev vehicle network based on CPN

2018 ◽  
Vol 176 ◽  
pp. 01016
Author(s):  
Yibo Jiao ◽  
Xiangqian liu ◽  
Xiaoyong Chen
Keyword(s):  
Magnetic Levitation ◽  
Colored Petri Nets ◽  
Network System ◽  
Maglev Train ◽  
Modeling And Analysis ◽  
Maglev Vehicle ◽  
Medium Speed ◽  
Original Scheme ◽  
Improvement Scheme ◽  
Vehicle Network

With the upsurge of magnetic levitation construction and research in China, in order to improve the running speed of mid-low-speed maglev train, the 13th Five-Year Science and Technology Major Proposal put forward a medium speed maglev solution with long stator synchronous traction. According to this new plan, the magnetic levitation subsystem, including the control system, needs re-co-ordination design, and the car network system must be changed accordingly. In this paper, based on the original scheme, a new magnetic levitation vehicle network system is designed to meet the needs of localization. In this paper, colored Petri nets are used to model and analyze the original scheme and the improved scheme. It proves theoretically that the improvement scheme is superior to the original scheme in failure rate and can meet the actual project requirements.

scholarly journals Adaptive Backoff Algorithm for Contention Window for Dense IEEE 802.11 WLANs

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Ikram Syed ◽  
Byeong-hee Roh
Keyword(s):  
Ieee 802.11 ◽  
Network Performance ◽  
Contention Window ◽  
Collision Probability ◽  
System Throughput ◽  
Channel State ◽  
Backoff Algorithm ◽  
802.11 Dcf ◽  
802.11 Wlans ◽  
Lower Collision

The performance improvement in IEEE 802.11 WLANs in widely fluctuating network loads is a challenging task. To improve the performance in this saturated state, we develop an adaptive backoff algorithm that maximizes the system throughput, reduces the collision probability, and maintains a high fairness for the IEEE 802.11 DCF under dense network conditions. In this paper, we present two main advantages of the proposed ABA-CW algorithm. First, it estimates the number of active stations and then calculates an optimal contention window based on the active station number. Each station calculates the channel state probabilities by observing the channel for the total backoff period. Based on these channel states probabilities, each station can estimate the number of active stations in the network, after which it calculates the optimal CW utilizing the estimated active number of stations. To evaluate the proposed mechanism, we derive an analytical model to determine the network performance. From our results, the proposed ABA-CW mechanism achieved better system performance compared to fixed-CW (BEB, EIED, LILD, and SETL) and adaptive-CW (AMOCW, Idle Sense) mechanisms. The simulation results confirmed the outstanding performance of the proposed mechanism in that it led to a lower collision probability, higher throughput, and high fairness.

WSN02-1: Analysis of IEEE 802.11 DCF with Hidden Terminals

2006 ◽  
Author(s):  
Haitao Wu ◽  
Fan Zhu ◽  
Qian Zhang ◽  
Zhisheng Niu
Keyword(s):  
Ieee 802.11 ◽  
Ieee 802.11 Dcf ◽  
802.11 Dcf ◽  
Hidden Terminals

Research and Simulation Base on Asynchronous Motor Soft Starter

2011 ◽  
Vol 403-408 ◽  
pp. 3615-3619
Author(s):  
Gang Zhao ◽  
Lei Wang
Keyword(s):  
Asynchronous Motor ◽  
Paper Analysis ◽  
Matlab Simulation ◽  
Control Effect ◽  
Squirrel Cage ◽  
Current Limit ◽  
Soft Starter ◽  
Voltage Ramp ◽  
Voltage Limit ◽  
The Impact

Soft-Starter is a new equipment and it is used to control Squirrel-Cage Induction Motors because of its pefect control effect, compared with the traditional Start method. This paper analysis the superiority of Voltage Ramp and current limit control algorithm.The MATLAB simulation result base on 4.7KW Motor shown that the soft-starter can be used to Reduce the start voltage, limit start Current and Reduce the impact on power. Correctness and validity of algorithms is verified by simulation results.

MAP-NPS: A Novel Media Access Protocol Based on Node Pair Sequencing for Underwater Acoustic Networks

2014 ◽  
Vol 568-570 ◽  
pp. 561-567
Author(s):  
Sheng Quan Wang ◽  
Da Jun Sun ◽  
You Wen Zhang
Keyword(s):  
Mac Protocol ◽  
Propagation Delay ◽  
Media Access ◽  
Access Protocol ◽  
Underwater Acoustic ◽  
Node Pair ◽  
Hidden Terminals ◽  
Acoustic Networks ◽  
Underwater Acoustic Networks

In this paper, we propose and analyze an new MAC protocol based on node pair sequencing (MAP-NPS), which requires node pairs achieved successful handshakes to realize multiple transmissions orderly after one-off RTS-CTS competition. We analyze and assess the protocol’s performance via simulations. Compared to the MACA-U [1] protocol and the PCAP [2] protocol, we show that the new protocol have better performance,which can improve throughput, decrease the propagation delay and reduce hidden terminals and exposed terminals.

An Improved Multi-Label Anti-Collision Algorithm of RFID

2013 ◽  
Vol 336-338 ◽  
pp. 1887-1891
Author(s):  
Jian Zhe Chen ◽  
Gui Tang Wang ◽  
Mei Shao ◽  
Ying Ge Li
Keyword(s):  
Search Algorithm ◽  
Data Communication ◽  
Communication Process ◽  
System Throughput ◽  
Redundant Information ◽  
Matlab Simulation ◽  
Throughput Rate ◽  
Rfid System ◽  
Electronic Tags ◽  
Data Collision

When there are multiple electronic tags in the reading range of reader, It arises problem of multiple tags data collision in the data communication process of RFID system, causing the data reader have obtained error. This paper will contrapose the problem of tag collision, analysizing the search number and the system throughput rate of the existing anti-collision search algorithm based on binary, to propose an improved anti-collision algorithm. The improved algorithm reduces the redundant information of the sequence number that the reader have sent, and no longer searchs the tags of one bit collided ,but identify the two collided tags directly, thus reducing the search number of algorithm. Matlab simulation show that this algorithm can reduce the search number of reader identifying tags, improving the identifying efficiency of the RFID system, solving the problem of tag collision effectively.

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