Performance Analysis of Collision using IEEE 802 . 11 (original) (raw)
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Performance Analysis of Collision Avoidance MAC Protocol in Multi-Hop Wireless Ad-Hoc Network
International Journal of Network and Mobile Technologies, 2011
Performance analysis of 802.11Medium Access Control (MAC) protocol has been carried out either by means of simulation or by means of analytical models with simplified back-off rule assumptions. Binary Exponential Back-off (BEB) is the widely used back-off mechanism in many contention-based IEEE 802.11 MAC protocols for its simplicity and good performance, but it has drawbacks especially in multi-hop ad hoc network and some new back-off schemes such as Multiplicative Increase and Linear Decrease (MILD) and Double Increment Double Decrement (DIDD) were proposed. This paper, investigate the performance of collision avoidance MAC protocol in multi-hop wireless ad-hoc network by adopting MILD back-off mechanism. A three state Markov chain is used to model the channel states and node states. These models were used to derive the duration time, steady-state probabilities of the states of node and throughput of Mobile Ad-hoc NETwork (MANET). Simulation results show no matter the value of average number of neighbors , transmission range , and length of DATA frames , the throughput of MANET always achieves the maximum value at some point of persistent probability and also the throughput of a MANETs increases with increase in persistent probability which is influenced by the number of neighbors, transmission range and length of DATA frame. On the other hand the throughput decreases with increase in sensing range which is also influenced by the number of neighbors, transmission range and length of DATA frame.
Modeling and Analysis of Collision Avoidance MAC Protocol in Multi-Hop Wireless Ad-Hoc Network
International Journal of Communication Networks and Information Security (IJCNIS), 2011
The absence of centralized administration, multi-hop transmission, and the nature of wireless channels pose many challenging research area in Mobile Ad hoc NETworks (MANETs). In this paper, a collision avoidance Medium Access Control (MAC) protocol was used for the modeling and analysis of multi-hop wireless ad hoc network, in which RTS/CTS/DATA/ACK handshake and Exponential Increase Exponential Decrease (EIED) back-off mechanism were adopted. A simple n-vertex undirected graph G(V, A) is used to model the topology of MANET while three-state Markov chain was used to model channel state and node state of MANET. Simulation results show that throughput increases with increase in persistent probability, sensing range and length of a DATA frame. Also throughput has a peak value at some point of the persistent probability, sensing range and length of a DATA frame, which is influenced by the number of nodes. In the other hand throughput increases along with the increase of transmission range for some values, then it start decreasing with increase in transmission range. Furthermore throughput decreases with increase in the number of nodes and back-off time. In order to validate the proposed models, a performance comparison of the throughput of existing model with the throughput of the proposed model by considering persistent probability, sensing range, transmission range, length of DATA transmission and back-off time was carried out. The overall results show that the proposed model achieve better throughput than the existing model.
Wireless Personal Communications, 2014
Ad hoc networks have been proposed for emergency communication wherein the required infrastructure is unavailable. However, a major concern in Ad hoc networks is collisions. Even in infrastructure based wireless networks, when the number of contending nodes is high, more number of frame collisions occur which leads to drastic reduction in network performance. In all IEEE 802.11 based wireless and Ad hoc networks, the backoff algorithm dynamically controls the contention window of the nodes experiencing collisions. Even though several algorithms such as Binary Exponential Backoff, Double Increment Double Decrement backoff, Exponential Increase Exponential Decrease backoff, Hybrid Backoff, Binary Negative Exponential Backoff etc. have been proposed in the literature to enhance the performance of IEEE 802.11 Distributed Coordination Function (DCF) protocol, most of them have not been developed for real-traffic scenarios. Also the packet collision rate is high using these algorithms. So, in this paper, a new Contention Window based Multiplicative Increase Decrease Backoff (CWMIDB) algorithm is proposed for the DCF protocol to alleviate the number of collisions. Furthermore, the packet transmission procedure of the DCF protocol is modified to avoid channel capture effect and this is represented with a Markov chain model. A simple mathematical model is developed for transmission probability considering the non-saturated traffic and channel errors. Results show that the proposed CWMIDB algorithm provides superior quality-of-service parameters over existing backoff algorithms.
Throughput Analysis of IEEE 802.11 MAC Protocol in Multi-Hop Wireless Ad-Hoc Network
Journal of Science and Technology Research, 2010
Mobile ad hoc networks are highly dynamic networks characterized by the absence of physical infrastructure. In such networks, nodes are able to move, evolve concurrently and synchronize continuously with their neighbours. There have been many studies on modeling and throughput analysis of single-hop 802.11 wireless networks but only a few on the analysis of multi-hop wireless networks. In this paper, Markov chain based models of a collision avoidance MAC protocol for multi-hop wireless ad-hoc networks is employed. These models are used to derive the duration time, transmission probabilities, transition probabilities and steady-state probabilities of the states of node as well as the throughput of MANETs .Simulation results shows that throughput of a MANETs increases with increase in persistent probability, sensing range and length of a DATA frame and also it has a peak value at some point of the persistent probability, sensing range and length of a DATA frame, which is influenced by the number of nodes.
This paper presents and analyzes a collision avoidance mechanism that increases the throughput and decreases the delay in wireless local area networks. The analysis considers the IEEE 802.11 standard parameters employed in the Distributed Coordination Function used in the Ad Hoc mode operation. The mechanism is based on the Deferral Counter (DC) algorithm proposed in the HomePlug standard. The purpose of the Deferral Counter is to increase the contention window faster than the regular IEEE 802.11 backoff function to avoid collisions. Different from IEEE 802.11, the mechanism increments the contention window of the deferring stations to minimize collisions. We implement this mechanism in the ns-2 simulator in order to compare it with IEEE 802.11. We propose three different functions to use in the Deferral Counter mechanism and evaluate their performance considering network throughput, packet delay, and the percentage of overlapping transmissions. The results show that the proposed mechanism performs better when there are more than four active stations no matter the packet size. Furthermore, we also show that the DC function, which achieves the best network throughput depends on the packet size and the number of active nodes.
Mobile Ad Hoc Network for Collision Avoidance in Mac Protocol Using Logarithmic Back off Algorithm
Abstract: The main application of the VANETS is to provide the routing between the vehicles. During the transmission of data collisions may occur. To avoid the collision problems the Binary Exponential Back off(BEB) Algorithm is proposed. BEB results in a high delay in message transmission, collisions and ultimately wasting the limited accessible data transfer capacity. As every hub needs to get medium access before transmitting a message, in thick systems, the crash likelihood in the Media Access Control (MAC) layer gets to be high when a poor back off calculation is utilized. The Logarithmic calculation proposes some improvements to the back off algorithms that aim to efficiently use the channel and to reduce collisions. The algorithm under study is based on changing the incremental behavior of the back off value. This paper carries out a deeper study and analysis of the logarithmic back off algorithm that uses logarithmic increment instead of exponential extension of window size to eliminate the degrading effect of random number distribution. Keywords: MANETS, Back off Algorithm, Hidden Terminal problem, Exposed Terminal problem, Logarithmic Back off Algorithm. Title: Mobile Ad Hoc Network for Collision Avoidance in Mac Protocol Using Logarithmic Back off Algorithm Author: NAGAPRIYA BAVINENI, TARIK ELTAEIB International Journal of Computer Science and Information Technology Research ISSN 2348-1196 (print), ISSN 2348-120X (online) Research Publish Journals
A Mechanism to Mitigate Collision Rate in Wireless Local Networks
Presently, IEEE 802.11 DCF is MAC protocol applied in wireless local networks. DCF would be inefficient, since there are two types of overload: Collision time and channel's idle time. Present paper, evaluated the performance and proposed an efficient MAC protocol for these networks called D-CW. D-CW will decrease both the channel's idle time and the collision time. D-CW, by dividing the value of contention window (CW) by two, reduces the time required for a successful node forwarding, and by selecting variable contention window for packet forwarding from each node with a random uniform function, what if a successful forwarding or an unsuccessful one, decreases the collision time. Stations, after selecting a value from the window contention own, follow the Backoff mechanism, and after counting the number of their own idle slots, do the forwarding. Simulation results indicate D-CW can improve the throughput of the system, delay reduction and collision rate on 802.11 DCF significantly.
Journal of Communication and Information Systems, 2004
In this paper we present and analyze a collision avoidance mechanism to increase the throughput and decrease the delay in wireless local area networks. The analysis considers the IEEE 802. I I Standard parameters employed in the Distributed Coordination Function used in the Ad Hoc mode operation. The mechanism is based on the deferral counter (DC) algorithm proposed in HomePlug Standard. The purpose of the Deferral Counter is to increase the contention window faster than the regular backoff function from IEEE 802. I I to prevent collisions. Different from IEEE 802.11, the mechanism increments the contention window of the deferring stations to minimize collisions. We implement this mechanism in ns-2 simulator in order to compare it with IEEE 802.11. We propose three different functions to use in the Deferral Counter mechanism and evaluate their performances considering network throughput, packet delay, and the percentage of overlapping transmissions. Results show that the proposed mechanism performs better when there is more than four active stations no matter the packet size. Furthermore, we also show that the DC function that achieves the best network throughput depends on the packet size and the number of active nodes.
Mobile Ad Hoc Network for Collision Avoidance in Mac Protocol Using Logarithmic
The main application of the VANETS is to provide the routing between the vehicles. During the transmission of data collisions may occur. To avoid the collision problems the Binary Exponential Back off (BEB) Algorithm is proposed. BEB results in a high delay in message transmission, collisions and ultimately wasting the limited accessible data transfer capacity. As every hub needs to get medium access before transmitting a message, in thick systems, the crash likelihood in the Media Access Control (MAC) layer gets to be high when a poor back off calculation is utilized. The Logarithmic calculation proposes some improvements to the back off algorithms that aim to efficiently use the channel and to reduce collisions. The algorithm under study is based on changing the incremental behavior of the back off value. This paper carries out a deeper study and analysis of the logarithmic back off algorithm that uses logarithmic increment instead of exponential extension of window size to eliminate the degrading effect of random number distribution.
Analytical modelling in 802.11 ad hoc networks
Computer Communications, 2011
In this paper, we propose an analytical model for 802.11 ad hoc wireless networks. Our model consists in replacing a finite number of nodes by an equivalent continuum -characterized by a density of nodes -and disseminated in the network according to some distribution function. The key feature of the proposed model is that it permits taking into account the effect of interference, the CSMA/CA mechanism and radio propagation aspects in an easy and straightforward way. All assumptions in the model are assessed with extensive simulation results. Closed form formula of the signal to noise ratio and the mean capacity per node will be given, corroborated by extensive simulation results in ns-2.