scholarly journals Clustering Transmission Opportunity Length (CTOL) Model over Cognitive Radio Network

Sensors ◽  
2018 ◽  
Vol 18 (12) ◽  
pp. 4351 ◽  
Author(s):  
Mas Mohamad ◽  
Aduwati Sali ◽  
Fazirulhisyam Hashim ◽  
Rosdiadee Nordin ◽  
Osamu Takyu
Keyword(s):  
Dynamic Models ◽  
Wireless Local Area Network ◽  
Cognitive Radio Network ◽  
Local Area Network ◽  
Local Area ◽  
Primary User ◽  
Contention Window ◽  
Collision Probability ◽  
Area Network ◽  
Transmission Opportunity

This paper investigated the throughput performance of a secondary user (SU) for a random primary user (PU) activity in a realistic experimental model. This paper proposed a sensing and frame duration of the SU to maximize the SU throughput under the collision probability constraint. The throughput of the SU and the probability of collisions depend on the pattern of PU activities. The pattern of PU activity was obtained and modelled from the experimental data that measure the wireless local area network (WLAN) environment. The WLAN signal has detected the transmission opportunity length (TOL) which was analyzed and clustered into large and small durations in the CTOL model. The performance of the SU is then analyzed and compared with static and dynamic PU models. The results showed that the SU throughput in the CTOL model was higher than the static and dynamic models by almost 45% and 12.2% respectively. Furthermore, the probability of collisions in the network and the SU throughput were influenced by the value of the minimum contention window and the maximum back-off stage. The simulation results revealed that the higher contention window had worsened the SU throughput even though the channel has a higher number of TOLs.

scholarly journals An Adaptive Contention Window Scheme for 802.11ah WLANs

2018 ◽  
Vol 17 ◽  
pp. 01016
Author(s):  
Renzheng Gao ◽  
Xiaoying Lei ◽  
Qiang Hu
Keyword(s):  
Wireless Local Area Network ◽  
Local Area Network ◽  
Mac Protocol ◽  
Rapid Development ◽  
Window Size ◽  
Local Area ◽  
Contention Window ◽  
Collision Probability ◽  
Sleep Mode ◽  
Area Network

In order to cope with the rapid development of the Internet of things, IEEE working group has proposed a new wireless network technology, 802.11ah. IEEE 802.11ah operates at sub 1GHz band, and can provide long transmission range, wide coverage, while supporting more than 6,000 of station to be connected. In order to alleviate the high collision probability, 802.11ah MAC protocol involves in the RAW (restricted access window) mechanism combined with grouping mechanism. However, in 802.11ah WLAN (wireless local area network), most of the stations operate at sleep mode, and it is expected that at the start of a BI, the network suffers much higher collision probability than at the latter period of the BI. In order to improve these drawbacks, we propose an adaptive contention window scheme based on which an optimum contention window size is adapted at the start of the BI, and then gradually halved when the transmission completes successfully. Through conducting simulations, we prove that our proposed protocol can enhance the performance of 802.11ah WLAN.

scholarly journals The concept of Virtual Contention Window for 802.11 IBSS wireless local area network mathematic modeling

2012 ◽  
Vol 16 (6) ◽  
pp. 39-45
Author(s):  
A.V. Lazebnyi ◽  
Volodymyr Semenovych Lazebnyi
Keyword(s):  
Packet Loss ◽  
Wireless Lan ◽  
Wireless Local Area Network ◽  
Local Area Network ◽  
Local Area ◽  
Wireless Channel ◽  
Contention Window ◽  
Transmission Time ◽  
Area Network ◽  
Mathematic Modeling

The concept of a virtual contention window for assessment of temporal and probabilistic characteristics of the processes occurring in the wireless LAN 802.11 is considered. The relations for determining the transmission time delay of the data package, the uneven of transmission time, throughput of wireless channel, the probability of packet loss for networks with saturated load are proposed in this paper.

scholarly journals Novel Multi-AP Coordinated Transmission Scheme for 7th Generation WLAN 802.11be

Entropy ◽  
2020 ◽  
Vol 22 (12) ◽  
pp. 1426
Author(s):  
Woojin Ahn
Keyword(s):  
Wireless Local Area Network ◽  
Local Area Network ◽  
Markov Chain Model ◽  
Local Area ◽  
System Throughput ◽  
Area Network ◽  
Chain Model ◽  
Transmission Scheme ◽  
High Data ◽  
Transmission Opportunity

The demand for high-data-rate and time-sensitive applications, such as 4k/8k video streaming and real-time augmented reality (AR), virtual reality (VR), and gaming, has increased significantly. Addressing the inefficiency of distributed channel access and the fairness problem between uplink and downlink flows is crucial for the development of wireless local area network (WLAN) technologies. In this study, we propose a novel transmission scheme for IEEE 802.11be networks that addresses the fairness problem and improves the system throughput. Utilizing the concept of multi-AP coordinated OFDMA introduced in the 7th-generation WLAN IEEE 802.11be, the proposed transmission scheme allows an AP to share a granted transmission opportunity (TXOP) with nearby APs. A mathematically analysis of the throughput performance of the proposed schemes was performed using a Markov chain model. The simulation results verify that the scheme effectively improves the downlink fairness and the system throughput. Combined with the advanced multiuser (MU) features of IEEE 802.11ax, such as TUA, MU cascading sequence, and MU EDCA, the proposed scheme not only enhances downlink AP transmission, but also guarantees improved control over the medium. The scheme is carefully designed to be fully compatible with conventional IEEE 802.11 protocols, and is thus potentially universal.

Link-Level Simulator for Wireless local Area Network

2018 ◽  
Vol 6 (7) ◽  
pp. 314
Author(s):  
Chaithra. H. U ◽  
Vani H.R
Keyword(s):  
Wireless Local Area Network ◽  
Local Area Network ◽  
Local Area Networks ◽  
Local Area ◽  
Long Term Evolution ◽  
Wireless Local Area Networks ◽  
Area Network ◽  
Network Simulator ◽  
Term Evolution

Now a days in Wireless Local Area Networks (WLANs) used in different fields because its well-suited simulator and higher flexibility. The concept of WLAN  with  advanced 5th Generation technologies, related to a Internet-of-Thing (IOT). In this project, representing the Network Simulator (NS-2) used linked-level simulators for Wireless Local Area Networks and still utilized IEEE 802.11g/n/ac with advanced IEEE 802.11ah/af technology. Realization of the whole Wireless Local Area Networking linked-level simulators inspired by the recognized Vienna Long Term Evolution- simulators. As a outcome, this is achieved to link together that simulator to detailed performances of Wireless Local Area Networking with Long Term Evolution, operated in the similar RF bands. From the advanced 5th Generation support cellular networking, such explore is main because different coexistences scenario can arise linking wireless communicating system to the ISM and UHF bands.

PERANCANGAN ANTENA MIKROSTRIPRECTANGULAR

Jurnal Teknik ◽  
2018 ◽  
Vol 7 (1) ◽  
Author(s):  
Heru Abrianto
Keyword(s):  
Dielectric Constant ◽  
Patch Antenna ◽  
Wireless Lan ◽  
Microstrip Antenna ◽  
Wireless Local Area Network ◽  
Local Area Network ◽  
Local Area ◽  
Area Network ◽  
Dual Polarization ◽  
Feeding Technique

Microstrip antenna which designed with dual feeding at 2.4 GHz and 5.8 GHz can meet WLAN (Wireless Local Area Network) application.Antenna fabrication use PCB FR4 double layer with thickness 1.6 mm and dielectric constant value 4.4. The length of patch antenna according to calculation 28.63 mm, but to get needed parameter length of patch should be optimized to 53 mm. After examination, this antenna has VSWR 1.212 at 2.42 GHz and 1.502 at 5.8 GHz, RL -13.94 dB at 2.42 GHz and -20.357 dB at 5.8 GHz, gain of antenna 6.16 dB at 2.42 GHz and 6.91 dB at 5.8 GHz, the radiation pattern is bidirectional. Keywords : microstrip antenna, wireless LAN, dual polarization, single feeding technique

IEEE 802.11 Tutorial

2018 ◽  
Author(s):  
Kiramat
Keyword(s):  
Access Control ◽  
Ieee 802.11 ◽  
Wireless Local Area Network ◽  
Local Area Network ◽  
Local Area ◽  
Physical Layer ◽  
Media Access Control ◽  
Area Network ◽  
Media Access ◽  
Computer Communications

IEEE 802.11 is a set of media access control (MAC) and physical layer (PHY) specifications for implementing wireless local area network (WLAN) computer communications. Maintained by the Institute of Electrical and Electronics Engineers (IEEE) LAN/MAN Standards Committee (IEEE 802). This document highlights the main features of IEEE 802.11n variant such as MIMO, frame aggregation and beamforming along with the problems in this variant and their solutions

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