scholarly journals Wireless Multiple Access and Analog Oscillation Analysis in Microgrids: A Prony Approach

2012 ◽  
Vol 8 (10) ◽  
pp. 932683
Author(s):  
Shuping Gong ◽  
Husheng Li
Keyword(s):  
Multiple Access ◽  
System Stability ◽  
Modal Characteristics ◽  
Oscillation Analysis ◽  
Access Scheme ◽  
Measurement Units ◽  
Response Modes ◽  
Different Response ◽  
Code Division Multiple ◽  
Time Division

A key challenge in smart grid is to monitor the system modal characteristics of disturbance over a microgrid for system stability and diagnosis. The measurements at different phasor measurement units (PMUs) need to be reported to a processing center. Therefore, a multiple access scheme for wireless transmission is necessary to collect the measurements from PMUs. An analog oscillation analysis is carried out without demodulating the received signal. Both schemes of time-division multiple access (TDMA) and code-division multiple access (CDMA) are discussed. In both schemes, the Prony-based algorithms using the received signal to estimate the system modal characteristics, including the eigenvalues of the linear system and the amplitudes of different response modes, are proposed and analyzed. Two countermeasures, max-min ratio measure (MMRM) and variance measure (VM), are also proposed to prevent possible attacks of false reports. Numerical simulation results demonstrate the effectiveness of Prony-based algorithms and the two countermeasures.

Performance Analysis and Validation of Precision Multisatellite RF Measurement Scheme for Microsatellite Formations

2021 ◽  
Author(s):  
Chen Lin ◽  
Xiaojun Jin ◽  
Shiming Mo ◽  
Cong Hou ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Multiple Access ◽  
High Performance ◽  
Large Scale ◽  
Measurement Accuracy ◽  
Media Access Control ◽  
Satellite Measurement ◽  
Measurement Scheme ◽  
Rf Measurement ◽  
Code Division Multiple ◽  
Time Division

Abstract Almost all existing studies on inter-satellite radio frequency (RF) measurement have focused on two-satellite formations. Although some frequency division multiple access and code division multiple access multisatellite RF measurement schemes have been proposed, their poor scalability does not satisfy the inter-satellite measurement requirements of multisatellite formations, especially large-scale formations. Two-way ranging (TWR), which is based on a time division mechanism, is an effective solution that has been used for inter-satellite links in the global positioning system and Beidou navigation constellations. However, the high measurement accuracy achieved with TWR in these navigation constellations is heavily reliant on high-performance atomic clocks and the assistance of navigation ephemeris, which are not available on microsatellite platforms. This work focuses on a scalable multisatellite measurement scheme that adopts a distributed broadcast-based time division multiple access mechanism as the media access control layer and uses an asymmetric double-side TWR method as the physical layer. The measurement performance of the proposed scheme is evaluated through in-depth theoretical modeling, simulation verification, and experimental validation, along with a comprehensive comparison with the conventional TWR method. The experimental results show that centimeter-level measurement accuracy can be achieved with the proposed scheme when only a common miniaturized frequency source is used. This accuracy level is two orders of magnitude better than that of the TWR method, and thus satisfies the application requirements of general large-scale microsatellite formations.

Cost Models for Telecommunication Networks and Their Application to GSM Systems

2011 ◽  
pp. 143-150
Author(s):  
Klaus D. Hackbarth ◽  
J. Antonio Portilla ◽  
Ing. Carlos Diaz
Keyword(s):  
Mobile Networks ◽  
Multiple Access ◽  
Business Models ◽  
The United States ◽  
Telecommunication Networks ◽  
Cost Models ◽  
Saturation Stage ◽  
Key Issues ◽  
Code Division Multiple ◽  
Time Division

Currently mobile networks are one of the key issues in the information society. The use of cellular phones has been broadly extended since the middle 1990s, in Europe mainly with the GSM (Global System for Mobile Communication) system, and in the United States (U.S.) with the IS-54 system. The technologies on which these systems are based, Time Division Multiple Access (TDMA) and Code Division Multiple Access (CDMA) are completely developed, the networks are completely deployed and the business models are almost exhausted1 (Garrese, 2003). Therefore, these systems are in the saturation stage if we consider the network life cycle described by Ward, which is shown in Figure 1.

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