scholarly journals Sliding Group Window with Rebacking off for Collision Avoidance in High-Efficiency Wireless Networks

Mathematics ◽  
2021 ◽  
Vol 9 (19) ◽  
pp. 2461
Author(s):  
Alaa Omran Almagrabi ◽  
Rashid Ali ◽  
Yasser Difulah Al-Otaibi ◽  
Hadi Mohsen Oqaibi ◽  
Tahir Khurshaid
Keyword(s):  
Collision Avoidance ◽  
High Efficiency ◽  
Mac Protocol ◽  
Markov Chain Model ◽  
Point Estimation ◽  
Collision Probability ◽  
Chain Model ◽  
Collision Point ◽  
Access Channel ◽  
Uniform Dispersion

It is difficult for wireless local area networks (WLANs), IEEE 802.11ax high-efficiency WLAN (HEW), to join next-generation innovations such as 5th generation (5G) and Internet of Things (IoT) because they still have their conventional channel access mechanism as their essential medium access control (MAC) protocol. The MAC protocol uses a traditional binary exponential backoff (BEB) algorithm to access channel resources that depend on the noncognitive increment of contention parameters for collision avoidance. In BEB, the collision issue increases with the increase in connected devices in the network due to a fixed contention window size. The larger the size of the network, the larger the collision in the network. To avoid such a circumstance, in this paper, we propose a sliding group window (sGW) mechanism dependent on collision-point assessment in order to improve the performance of MAC protocol for HEW. The proposed algorithm additionally presents a rebacking off for collision avoidance (ReBOCA) system for sGW, which combines the uniform dispersion of the contention parameters. This variation of an ordinary backoff algorithm permits the reasonable sliding of the user groups in the case of collision. The algorithm explicitly accounts for the peculiarities of dense environments and backward compatibility. Key aspects of the proposed solution include collision-point estimation, rebacking off for collision distribution convergence for fair treatment, and adaptive sliding of group windows to mitigate contention unfairness. We further formulated a closed-form Markov chain model for the performance analysis of our proposed sGW with ReBOCA scheme. Theoretical and practical results prove that our proposed scheme achieved maximal efficiency, even under dense environments. An increase in throughput with a lower packet collision probability was achieved with the proposed mechanism, and the efficiency increased as the number of contending stations increased than compared to traditional BEB performance. Our proposed ReBOCA mechanism enhanced network throughput by 38.18% than compared to the conventional BEB mechanism.

A Backoff Algorithm for LOWPAN Based on the Dynamically Backoff Exponent

2015 ◽  
Vol 713-715 ◽  
pp. 1389-1393
Author(s):  
Ya Jun Zhang ◽  
Jin Liang Shi ◽  
Guo Rong Chen
Keyword(s):  
Ieee 802.15.4 ◽  
Mac Protocol ◽  
Markov Chain Model ◽  
Poor Performance ◽  
System Throughput ◽  
Chain Model ◽  
Backoff Algorithm ◽  
The Poor ◽  
Mathematical Derivation ◽  
Transmission Status

A mechanism that the backoff exponent changes dynamically was proposed aiming at the poor performance of backoff algorithm in IEEE 802.15.4 MAC protocol. The algorithm could adjust the initial backoff exponent according to the previous transmission status and the backoff exponent. A Markov chain model for the algorithm was established and the mathematical derivation for the model was carried out. The theoretical analysis and simulation results show that the model increases the channel access probability and system throughput. The optimized algorithm improves the performance of LOWPAN effectively.

scholarly journals Design and Modeling of Self-Adapting MAC (SaMAC) Protocol with Inconstant Contention Loss Probabilities

2018 ◽  
Vol 2018 ◽  
pp. 1-25
Author(s):  
Ante Kristić ◽  
Julije Ožegović ◽  
Ivan Kedžo
Keyword(s):  
Wireless Networks ◽  
Mac Protocol ◽  
Markov Chain Model ◽  
Loss Probability ◽  
Chain Model ◽  
Industrial Wireless Networks ◽  
802.11 Dcf ◽  
Loss Probabilities ◽  
Congested Networks ◽  
A Chain

Networks based on IEEE 802.11 standard are one of the main options for deployment in industrial environment. Degradation of throughput in congested networks and short-term unfairness are well-known drawbacks of 802.11 DCF and similar MAC protocols. Those shortcomings represent significant limitation in forecasted growth of wireless usage. This is especially important in industrial wireless networks (IWN) where the scalability of wireless MAC is one of the main requirements. In this paper, a novel self-adapting MAC protocol (SaMAC) is defined and mathematically modeled. SaMAC employs constrained countdown freezing enhanced with shifted window mechanism. As a result, the protocol outperforms 802.11 DCF standard as well as shifted contention window (SCW) and constrained countdown freezing (CPCF) protocols in achieved throughput, fairness, and jitter, while keeping simple implementation. Despite protocol’s simple design, it is shown that its mathematical model is extremely complex. For proposed protocol, the assumption of constant contention loss probability, which is normally used for modeling of MAC schemes, does not hold. In the presented multidimensional Markov chain model, a unique iterative method for determining contention loss probability is developed as well as a method for throughput calculation based on such a chain. Accuracy of the presented model is verified in several network scenarios. Considering the performance of the proposed protocol, authors believe that it could be of benefit to deploy it in heavily loaded wireless networks with timing constraints, such as IWNs.

PERFORMANCE EVALUATION OF A REQUEST-TDMA/CDMA PROTOCOL FOR WIRELESS NETWORKS

2001 ◽  
Vol 02 (01) ◽  
pp. 49-67 ◽  
Author(s):  
MAINAK CHATTERJEE ◽  
SAJAL K. DAS
Keyword(s):  
Wireless Networks ◽  
Waiting Time ◽  
Multiple Access ◽  
Transition Probabilities ◽  
Mac Protocol ◽  
Markov Chain Model ◽  
Time Frame ◽  
Chain Model ◽  
Request Message ◽  
Code Division Multiple

This paper proposes a new medium access control (MAC) protocol, called Request-TDMA/CDMA, for supporting multimedia traffic in wireless networks. In this hybrid protocol, CDMA (code division multiple access) is laid over TDMA (time division multiple access), where a time frame has two kinds of slots, namely data slots and control slots. The data slots are used to the user to transmit their data while the control slot holds the information for the next frame's slot allocation. Each data slot in a frame can be simultaneously used by multiple users with the help of uniquely assigned codes. Whenever a user needs to transmit a message, he first sends a request message to the central controller and enters the contention process. The controller takes into consideration the time of generation of a call, the bit rate requirement and the message length while reserving slots for the entire length of the message generated. The user then goes into the transmission phase if he is successful in the contention process, and continues to transmit his data till the entire message is sent. Three scheduling algorithms for the allocation of data slots are proposed and their performance are studied for four classes of traffic. We also analyze our protocol using a two-dimensional Markov chain model, and compute the state transition probabilities and derive the average waiting time for a given system load. By simulation experiments we show that our request-TDMA/CDMA protocol is able to effectively combine the orthogonality of both time and code division multiplexing. Further enhancements are also proposed to decrease the waiting time and increase the average channel utilization.

scholarly journals A multi-channel load awareness-based MAC protocol for flying ad hoc networks

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Bo Zheng ◽  
Yong Li ◽  
Wei Cheng ◽  
Huaxin Wu ◽  
Weilun Liu
Keyword(s):  
Ad Hoc Network ◽  
Ad Hoc ◽  
Mobile Ad Hoc Network ◽  
Model Simulation ◽  
Mac Protocol ◽  
Markov Chain Model ◽  
Chain Model ◽  
Distributed Coordination ◽  
Network Bandwidth ◽  
Priority Queueing

Abstract Flying ad hoc network (FANET) is a promising and special mobile Ad hoc network, connecting large number of flying unmanned aerial vehicles (UAVs) on battlefield through wireless link. Designing a multi-priority traffic differentiated medium access control (MAC) protocol with low delay, large capacity, high flexibility, and strong scalability is a great challenge in the researches and applications of FANETs. In order to overcome the disadvantages in IEEE 802.11 distributed coordination function (DCF) and time division multiple access (TDMA) protocols, a novel multi-channel load awareness-based MAC protocol for FANETs is presented in this paper. The multi-priority queueing and service mechanism, and the multi-channel load-based backoff mechanism involved in the protocol are intensively described. We further model the multi-priority queueing and service mechanism by the multi-class queueing theory, and model the backoff mechanism using the Markov chain model. Simulation results show that the protocol can differentiate services for different priorities in FANETs according to real-time channel state, providing effective QoS guarantee for transmissions of various information, and the network bandwidth resource is efficiently utilized.

Analysis of the Multi-Channel MAC Protocols in Wireless Networks

2013 ◽  
Vol 756-759 ◽  
pp. 2734-2738
Author(s):  
Chun Guang Shi ◽  
Hai Tao Zhao ◽  
Yi Tang ◽  
Yun Feng Zhou
Keyword(s):  
Wireless Networks ◽  
Markov Chain ◽  
Single Channel ◽  
Mac Protocol ◽  
Markov Chain Model ◽  
Mac Protocols ◽  
Protocol Design ◽  
Network Throughput ◽  
Chain Model

This paper discusses the problems that may be encountered in a multi-channel MAC protocol design. Furthermore, the normalization network throughput of multi-channel MAC is analyzed based on a Markov chain model. The simulation shows that compared to single channel 802.11, multi-channel MAC can improve the normalization network throughput. Moreover, the greater is the number of divided sub-channels, the higher is the normalization network throughput.

scholarly journals Dynamic Channel Slot Allocation Scheme and Performance Analysis of Cyclic Quorum Multichannel MAC Protocol

2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Xing Hu ◽  
Linhua Ma ◽  
Shaocheng Huang ◽  
Tianyu Huang ◽  
Shiping Liu
Keyword(s):  
Single Channel ◽  
Mac Protocol ◽  
Markov Chain Model ◽  
Chain Model ◽  
Distributed Coordination ◽  
Quorum System ◽  
Slot Allocation ◽  
Dynamic Channel ◽  
Simulation Results ◽  
Multichannel Mac

In high diversity node situation, multichannel MAC protocol can improve the frequency efficiency, owing to fewer collisions compared with single-channel MAC protocol. And the performance of cyclic quorum-based multichannel (CQM) MAC protocol is outstanding. Based on cyclic quorum system and channel slot allocation, it can avoid the bottleneck that others suffered from and can be easily realized with only one transceiver. To obtain the accurate performance of CQM MAC protocol, a Markov chain model, which combines the channel-hopping strategy of CQM protocol and IEEE 802.11 distributed coordination function (DCF), is proposed. The results of numerical analysis show that the optimal performance of CQM protocol can be obtained in saturation bound situation. And then we obtain the saturation bound of CQM system by bird swarm algorithm. In addition, to improve the performance of CQM protocol in unsaturation situation, a dynamic channel slot allocation of CQM (DCQM) protocol is proposed, based on wavelet neural network. Finally, the performance of CQM protocol and DCQM protocol is simulated by Qualnet platform. And the simulation results show that the analytic and simulation results match very well; the DCQM performs better in unsaturation situation.

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