scholarly journals A Simple and Practical Scheme Using Multiple Channels for Improving System Spectral Efficiency of Highly Dense Wireless LANs

2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Jungmin So ◽  
Joosang Lee
Keyword(s):  
Single Channel ◽  
Wireless Lans ◽  
Multiple Channels ◽  
Medium Access ◽  
Simple Scheme ◽  
Carrier Sense ◽  
Hidden Terminals ◽  
Carrier Sensing ◽  
Simulation Results ◽  
Practical Scheme

As the density of wireless LANs increases, performance degradation caused by hidden terminals and exposed terminals becomes significant. These problems come from carrier sensing based medium access control used in current wireless LANs. Hidden terminals are created if carrier sense threshold is too high, whereas exposed terminals are created if carrier sense threshold is too low. A good threshold depends on how far nodes are placed from their destinations, but that cannot be controlled by the system. In this paper, we propose a simple scheme that makes use of multiple channels. Multiple channels could be utilized by equipping multiple radios or using advanced hardware such as SDR to divide a single channel into multiple channels. Nodes are assigned channels based on their estimated distance from the AP. Once the assignment is done, carrier sense threshold for the channel is selected so that as many concurrent transmissions take place as possible, while preventing hidden terminals. Simulation results show that the proposed mechanism achieves significantly higher throughput without causing starvation at the edge nodes.

scholarly journals Dynamic Carrier-Sense Threshold Selection for Improving Spatial Reuse in Dense Wireless LANs

2019 ◽  
Vol 9 (19) ◽  
pp. 3951 ◽  
Author(s):  
Jungmin So ◽  
Joosang Lee
Keyword(s):  
Wireless Lan ◽  
Medium Access Control Protocol ◽  
System Throughput ◽  
Spatial Reuse ◽  
Medium Access ◽  
Packet Losses ◽  
Single Carrier ◽  
Carrier Sense ◽  
Carrier Sensing ◽  
Key Techniques

As density of a wireless LAN grows, per-user throughput degrades severely, deteriorating user experience. To improve service quality, it is important to increase system spectral efficiency. Controlling carrier-sense threshold is one of the key techniques to achieve the goal, because frequently transmissions are unnecessarily blocked by carrier sensing, even though these transmissions can take place without causing packet losses. Using high carrier-sense threshold and allowing nodes to transmit aggressively may increase the system throughput, but this approach can lead to unfair channel share and cause starvation for the edge nodes. In this paper, we propose a medium access control protocol where transmitters include the carrier-sense threshold required to protect its packet in the preamble. Nodes receiving the preamble only transmit concurrently, when they are confident that their own transmission as well as the on-going transmission will both be successfully received at the respective receivers. The simulation results show that this dual-threshold approach can achieve higher system throughput compared to using a single carrier-sense threshold, without penalizing edge nodes.

scholarly journals G-DCF: Improving System Spectral Efficiency through Concurrent Transmissions in Wireless LANs

2019 ◽  
Vol 2019 ◽  
pp. 1-16
Author(s):  
Ayinebyona Eliab ◽  
Yonghwi Kim ◽  
Joosang Lee ◽  
Jeong-Gun Lee ◽  
Jungmin So
Keyword(s):  
Spectral Efficiency ◽  
Mac Protocol ◽  
Wireless Lans ◽  
Performance Evaluations ◽  
System Throughput ◽  
Spatial Reuse ◽  
Fair Share ◽  
802.11 Dcf ◽  
Carrier Sense ◽  
Carrier Sensing

This paper presents G-DCF, a MAC protocol for wireless LANs that can improve system spectral efficiency of wireless LANs by allowing more concurrent transmissions. The 802.11 DCF creates exposed terminals which are nodes that can transmit successfully but are blocked by carrier sensing. More potential exposed terminals are created when APs are densely placed, limiting spatial reuse of channels and thus system throughput. In order to allow concurrent transmissions from exposed terminals, G-DCF establishes groups in the network. Members of a group are nodes located within the carrier sense range of each other but can transmit packets concurrently. Whenever one member of a group wins the channel and transmits its packet, other nodes in the group also start transmission, triggered by the group ID included in the preamble. Contention window is adjusted according to the group size for fair share of the channel. Performance evaluations show that G-DCF can significantly improve system throughput and fairness over 802.11 DCF, especially when the APs are densely deployed.

FSO-Based Analysis of LTE-A MAC Protocols to Achieve Improved QoS

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Prabhjot Kaur ◽  
Hardeep Singh Saini
Keyword(s):  
Data Transmission ◽  
Orthogonal Frequency Division Multiplexing ◽  
Optical Signal ◽  
Transmission Efficiency ◽  
Mac Protocols ◽  
Wireless Access Networks ◽  
Free Space Optical ◽  
Medium Access ◽  
Carrier Sense ◽  
Efficient Data

AbstractFiber wireless (Fi-Wi) communication network is the amalgamation of optical and wireless access networks, which provides better bandwidth for achieving efficient data transmission. Medium access control (MAC) protocols are used in the wireless network for controlling the data flow from the transmitter to the receiver end. The delay produced by these protocols tells about the system efficiency. This paper shows a Fi-Wi system in the long-term evaluation-advanced (LTE-A) environment, which incorporates the dependency of delay generated by the specific MAC protocols during the transmission process. This paper aimed to scrutinize the effects of Carrier Sense Multiplexing Access with Collision Detection (CSMA/CD), Carrier Sense Multiplexing Access with Collision Avoidance (CSMA/CA) and Slotted ALOHA on the performance of the Fi-Wi system. Free space optical (FSO) channel is incorporated to forward the data to user end. In such system, the optical signal is multiplexed using the Orthogonal Frequency Division Multiplexing (OFDM) technique and finally the data are fetched at the receiver end and different criterions such eye-height, Q-factor and bit error rate are evaluated. Simulation results are performed using MATLAB software. The comparative analysis is also performed in terms of data transmission efficiency, delay and throughput of MAC protocols. This shows the effective results of the proposed system according to the delay produced by MAC protocols.

scholarly journals Generalization of the model-independent Laurent–Pietarinen single-channel pole-extraction formalism to multiple channels

2016 ◽  
Vol 755 ◽  
pp. 452-455 ◽  
Author(s):  
Alfred Švarc ◽  
Mirza Hadžimehmedović ◽  
Hedim Osmanović ◽  
Jugoslav Stahov ◽  
Lothar Tiator ◽  
...  
Keyword(s):  
Single Channel ◽  
Multiple Channels ◽  
Model Independent

WLC10-5: Performance Analysis of Slotted Carrier Sense IEEE 802.15.4 Medium Access Layer

2006 ◽  
Author(s):  
Sofie Pollin ◽  
Mustafa Ergen ◽  
Sinem Coleri Ergen ◽  
Bruno Bougard ◽  
Liesbet Van Der Perre ◽  
...  
Keyword(s):  
Performance Analysis ◽  
Ieee 802.15.4 ◽  
Medium Access ◽  
Carrier Sense

scholarly journals Review of MAC Protocols for Vehicular Ad Hoc Networks

Sensors ◽  
2020 ◽  
Vol 20 (23) ◽  
pp. 6709
Author(s):  
Mengyuan Ma ◽  
Kai Liu ◽  
Xiling Luo ◽  
Tao Zhang ◽  
Feng Liu
Keyword(s):  
Ad Hoc Networks ◽  
Vehicular Ad Hoc Networks ◽  
Ad Hoc ◽  
Single Channel ◽  
Hierarchical Structures ◽  
Mac Protocols ◽  
Medium Access ◽  
Design And Optimization ◽  
Advantages And Disadvantages ◽  
Hoc Networks

Vehicular ad hoc networks (VANETs) need to support the timely end-to-end transmissions of safety and non-safety messages. Medium access control (MAC) protocols can ensure fair and efficient sharing of channel resources among multiple vehicles for VANETs, which can provide timely packet transmissions and significantly improve road safety. In this paper, we review the standards of some countries for VANETs. Then, we divide the MAC protocols proposed for VANETs into single-channel MAC protocols and multi-channel MAC protocols according to the number of physical occupied spectrum resources. Both are further discussed based on their hierarchical structures, i.e., distributed and centralized structures. General design and optimization mechanisms of these commonly used MAC protocols for VANETs are reviewed. From the viewpoint of 7 aspects, we compare the advantages and disadvantages of these typical MAC protocols. Finally, we discuss the open issues to improve the MAC performance and future work on MAC design for VANETs.

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