scholarly journals Hierarchical Slotted Wireless Random Channel Access with Power Control

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Abdelillah Karouit ◽  
Luis Orozco Barbosa ◽  
Fernando Ramírez-Mireles ◽  
Abdelkrim Haqiq
Keyword(s):  
Power Control ◽  
Power Level ◽  
Random Access ◽  
Packet Transmission ◽  
System Throughput ◽  
Channel Access ◽  
Access Scheme ◽  
Control Scheme ◽  
Average System

This paper introduces a hierarchical Wireless Random Access scheme based on power control where intelligence is split among the mobile users in order to drive the outcome of the system towards an efficient point. The hierarchical game is obtained by introducing a special user who plays the role of altruistic leader whereas the other users assume the role of followers. We define the power control scheme in such a way that the leader_first chooses the lowest power to transmit its packets amongNavailable levels whereas the followers re-transmit by randomly choosing a power level picked fromN-1higher distinct power levels. Using a 3D Markovian model, we compute the steady state of the system and derive the average system throughput and expected packet transmission delay. Our numerical results show that the proposed scheme considerably improves the global performance of the system avoiding the well known throughput collapse at high loads commonly characterizing most random channel access mechanisms.

scholarly journals OFDMA Backoff Control Scheme for Improving Channel Efficiency in the Dynamic Network Environment of IEEE 802.11ax WLANs

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5111
Author(s):  
Youngboo Kim ◽  
Lam Kwon ◽  
Eun-Chan Park
Keyword(s):  
Random Access ◽  
Dynamic Network ◽  
Access Point ◽  
Local Area ◽  
Channel Access ◽  
Signaling Mechanism ◽  
Ieee 802.11Ax ◽  
Channel Efficiency ◽  
Control Scheme ◽  
New Feature

IEEE 802.11ax uplink orthogonal frequency division multiple access (OFDMA)-based random access (UORA) is a new feature for random channel access in wireless local area networks (WLANs). Similar to the legacy random access scheme in WLANs, UORA performs the OFDMA backoff (OBO) procedure to access the channel and decides on a random OBO counter within the OFDMA contention window (OCW) value. An access point (AP) can determine the OCW range and inform each station (STA) of it. However, how to determine a reasonable OCW range is beyond the scope of the IEEE 802.11ax standard. The OCW range is crucial to the UORA performance, and it primarily depends on the number of contending STAs, but it is challenging for the AP to accurately and quickly estimate or keep track of the number of contending STAs without the aid of a specific signaling mechanism. In addition, the one for this purpose incurs an additional delay and overhead in the channel access procedure. Therefore, the performance of a UORA scheme can be degraded by an improper OCW range, especially when the number of contending STAs changes dynamically. We first observed the effect of OCW values on channel efficiency and derived its optimal value from an analytical model. Next, we proposed a simple yet effective OBO control scheme where each STA determines its own OBO counter in a distributed manner rather than adjusting the OCW value globally. In the proposed scheme, each STA determines an appropriate OBO counter depending on whether the previous transmission was successful or not so that collisions can be mitigated without leaving OFDMA resource units unnecessarily idle. The results of a simulation study confirm that the throughput of the proposed scheme is comparable to the optimal OCW-based scheme and is improved by up to 15 times compared to the standard UORA scheme.

scholarly journals A Power Control Scheme to Exploit Capture Effect with Fairness Consideration in WLAN

2021 ◽  
Author(s):  
Szu-Lin Su ◽  
Tsung-Hsiu Chih ◽  
Yuan-Chun Tsai ◽  
Hsieh-Cheng Liao ◽  
Yu-Chia Wang
Keyword(s):  
Power Control ◽  
Window Size ◽  
Access Point ◽  
Mass Function ◽  
System Throughput ◽  
Probability Mass Function ◽  
Cross Layer Design ◽  
Capture Effect ◽  
Medium Access ◽  
Control Scheme

AbstractIn this paper, we develop a physical/medium-access-control cross layer design to improve system throughput with the consideration of fairness for IEEE 802.11 WLAN. From PHY layer perspective, when an access collision occurs, the access point can still decode the corresponding data successfully if the received signal to interference plus noise ratio is larger than the threshold. This phenomenon is referred to as the capture effect. To improve system throughput, this work proposes a Differential Reception-Power Power Control scheme to take advantage of the capture effect. However, the proposed power control scheme cannot provide a fair transmission environment even though it improves the system throughput. To resolve this problem, this work proposes two methods: the adjustment of contention window size and the modification of probability mass function for the selection of the backoff value. The simulation results demonstrate that the proposed schemes can not only remarkably improve system throughput, but also provide a fair transmission environment.

Examining the Role of Power-Control Theory and Self-Control to Account for Computer Hacking

2020 ◽  
pp. 001112872098189
Author(s):  
Thomas J. Holt ◽  
Kevin F. Steinmetz
Keyword(s):  
Gender Difference ◽  
Control Theory ◽  
Power Control ◽  
Gender Disparity ◽  
Criminological Theory ◽  
Self Control ◽  
Self Report ◽  
Computer Hacking ◽  
Using Data

Criminological inquiry consistently identifies a gender difference in offending rates, which are also evident among certain forms of cybercrime. The gender difference in cybercrime offending is particularly large within computer hacking, though few have specifically addressed this issue through applications of criminological theory. The current study attempted to account for the gender disparity in hacking through a test of power-control theory, which considers the role of class and family structure. This analysis also incorporated an extension of power-control theory through the influence of low self-control. Using data from the Second International Self-Report of Delinquency study (ISRD-2), logistic regression analyses were estimated, producing partial support for both theories to account for hacking. Implications for theory and research were explored in detail.

scholarly journals A Poisson Process-Based Random Access Channel for 5G and Beyond Networks

Mathematics ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 508
Author(s):  
Alaa Omran Almagrabi ◽  
Rashid Ali ◽  
Daniyal Alghazzawi ◽  
Abdullah AlBarakati ◽  
Tahir Khurshaid
Keyword(s):  
Poisson Process ◽  
Random Access ◽  
Communication Technologies ◽  
Channel Access ◽  
Access Channel ◽  
Machine Type Communications ◽  
Equal Chance ◽  
Random Access Channel ◽  
Access Mechanisms

The 5th generation (5G) wireless networks propose to address a variety of usage scenarios, such as enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), and ultra-reliable low-latency communications (URLLC). Due to the exponential increase in the user equipment (UE) devices of wireless communication technologies, 5G and beyond networks (B5G) expect to support far higher user density and far lower latency than currently deployed cellular technologies, like long-term evolution-Advanced (LTE-A). However, one of the critical challenges for B5G is finding a clever way for various channel access mechanisms to maintain dense UE deployments. Random access channel (RACH) is a mandatory procedure for the UEs to connect with the evolved node B (eNB). The performance of the RACH directly affects the performance of the entire network. Currently, RACH uses a uniform distribution-based (UD) random access to prevent a possible network collision among multiple UEs attempting to access channel resources. However, in a UD-based channel access, every UE has an equal chance to choose a similar contention preamble close to the expected value, which causes an increase in the collision among the UEs. Therefore, in this paper, we propose a Poisson process-based RACH (2PRACH) alternative to a UD-based RACH. A Poisson process-based distribution, such as exponential distribution, disperses the random preambles between two bounds in a Poisson point method, where random variables occur continuously and independently with a constant parametric rate. In this way, our proposed 2PRACH approach distributes the UEs in a probability distribution of a parametric collection. Simulation results show that the shift of RACH from UD-based channel access to a Poisson process-based distribution enhances the reliability and lowers the network’s latency.

scholarly journals Route towards efficient magnetization reversal driven by voltage control of magnetic anisotropy

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Roxana-Alina One ◽  
Hélène Béa ◽  
Sever Mican ◽  
Marius Joldos ◽  
Pedro Brandão Veiga ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Random Access ◽  
Low Power Consumption ◽  
Surface Anisotropy ◽  
Magnetization Dynamics ◽  
Storage Density ◽  
Switching Regime ◽  
Major Interest ◽  
Out Of Plane

AbstractThe voltage controlled magnetic anisotropy (VCMA) becomes a subject of major interest for spintronics due to its promising potential outcome: fast magnetization manipulation in magnetoresistive random access memories with enhanced storage density and very low power consumption. Using a macrospin approach, we carried out a thorough analysis of the role of the VCMA on the magnetization dynamics of nanostructures with out-of-plane magnetic anisotropy. Diagrams of the magnetization switching have been computed depending on the material and experiment parameters (surface anisotropy, Gilbert damping, duration/amplitude of electric and magnetic field pulses) thus allowing predictive sets of parameters for optimum switching experiments. Two characteristic times of the trajectory of the magnetization were analyzed analytically and numerically setting a lower limit for the duration of the pulses. An interesting switching regime has been identified where the precessional reversal of magnetization does not depend on the voltage pulse duration. This represents a promising path for the magnetization control by VCMA with enhanced versatility.

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