Impact Of Mobility and Transmission Range On The Performance of Backoff Algorithms For IEEE 802.11-Based Multi-hop Mobile Ad hoc Networks (original) (raw)

A New Backoff Algorithm for Ieee 802.11 DCF Mac Protocol in Mobile Ad Hoc Networks

2011

Backoff algorithms are one class of collision resolution algorithms used in the medium access control protocol in mobile ad hoc networks. When there are different nodes competing to access a shared channel at the same time, the possibility of collision is highly probable, especially in high traffic load networks. Collision is considered as the major problem in wireless networks, so

Performance Comparison of IEEE 802.11 Back-off Mechanisms in Multi-Hop Wireless Ad-Hoc Network

Journal of Engineering Science and Technology , 2009

Binary Exponential Back-off (BEB) is widely used 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 Exponential Increase Exponential Decrease (EIED) were proposed. In this paper, performances of three back-off BEB, MILD, and EIED schemes in a multi-hop ad-hoc network are compared. A Markov chain is used to model the channel states and node states of a contention-based IEEE 802.11 DCF protocol in which RTS/CTS/DATA/ACK handshake and three kinds of back-off mechanisms are adopted. These models are used to derive the duration time and steady-state probabilities of the states of node as well as estimated throughput of MANETs. Simulation results revealed that throughput decreases with increase in back-off time, BEB has the longest back-off time and lowest throughput, MILD has the shortest back-off time and highest throughput while EIED has back-off time and throughput between that of BEB and MILD.

Performance Analysis of Backoff Algorithm in IEEE 802.11 Networks

ijser.org

The primary Medium Access Control (MAC) technique of IEEE 802.11 is called Distributed Coordination Function (DCF). This protocol adopts a Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) with a binary exponential backoff (BEB) algorithm to access the channel. The protocol performance mainly depends on backoff procedure which reduces the probability of collision. With BEB, waiting time of a node gets doubled after every unsuccessful transmission. This introduces fast-growing retransmission delays for the backlog traffic. In a mobile ad hoc network (MANET), it would be worthwhile to slow down the growth-rate of waiting time because the nodes communicating in a MANET might move out of collision range while waiting for retransmission. Moreover, DCF reduces the Contention Window to the initial value after each successful transmission which essentially assumes that each successful transmission is an indication that the system is under low traffic loading. In this paper analyzed the problem with existing Backoff Algorithm.

Performance evaluation of backoff algorithms in 802.11 ad-hoc networks

… international workshop on Performance …, 2006

Understanding the performance of backoff algorithms in multihop ad hoc networks is a key feature to design efficient Medium Access Protocols for wireless networks. The 802.11 backoff algortihm, the Binary Exponential Backoff, and all the enhancement done to this algorithm are studied in depth in a single hop context. Very few analytical studies are done on 802.11 backoff algorithms in a multi-hop context due to the difficulty of modelling. In this paper we propose an analytical study, based on process algebra, of 4 backoff algorithms on 2 multi-hop scenarios. We evaluate the performance of each backoff algorithms from efficiency point of view and when possible from a fairness point of view.

MAC layer back-off algorithm for ad hoc networks

Channel efficiency and channel throughput in any network are affected by packet collisions. Reduction of packet collisions plays a greater role in Mobile Ad hoc Networks (MANETs), due to the open medium topology where carrier sensing is not practical or feasible. Consequently, these collision issues introduce a key problem in MANET networks where researches proposed back-off mechanism to overcome packet collisions. Back-off algorithm is proposed to reduce collisions that happen when more than one node tries sending data on the channel simultaneously. The Binary Exponential Back-off (BEB), the first Back-off algorithm that is deployed in Medium Access Control layer, is used by IEEE 802.11 to avoid collision in MANETs. BEB algorithm uses a uniform random distribution Back-off values to solve the collision problem. In this paper, we propose Fibonacci Liner Increment Back-Off (FLB) algorithm to achieve an effective value for the Back-off timer of the nodes before accessing the channel t...

SBA: A Simple Backoff Algorithm for Wireless Ad Hoc Networks

NETWORKING 2009, 2009

The performance of ad hoc networks based on IEEE 802.11 DCF degrade when congestion increases. The issues concern efficiency and fairness. Many solutions can be found at the MAC layer in the literature, but very few solutions improve fairness and efficiency at the same time. In this paper, we design a new backoff solution, called SBA. SBA uses only local information and two contention window sizes. By simulations, we compare SBA with IEEE 802.11 and several alternatives to 802.11 in ad hoc networks. We show that SBA achieves a good tradeoff between fairness, simplicity and efficiency.

Effect of Medium Access Control (MAC) on the Throughput of Multi-Hop Wireless Ad-Hoc Network

Journal of Engineering and Applied Sciences, 2011

Medium Access Control (MAC) protocol is the main element that determines the efficiency in sharing the limited communication bandwidth of the wireless channel in IEEE 802.11 wireless networks. This paper, investigate the effect of MAC on throughput of multi-hop wireless adhoc network. A Markov chain is used to model a collision avoidance MAC protocol for multihop wireless ad-hoc networks. In the models, two fundamental issues in MAC, i.e., collisions and spatial reuse in terms of persistent probability, sensing range and back-off time mechanism were considered. Simulation results show that collision avoidance MAC mechanism such as persistent probability; sensing range and back-off time have significant effects on the performance of multi-hop wireless ad hoc networks. The effects of these MAC mechanisms were influenced by the number of neighbors, transmission range and length of data frame. It is observed that throughput increases with increase in persistent probability and also effect of sensing range on the throughput is weakening when the transmission range is short. Similarly throughput increases with increase in sensing range and back-off time when number of neighbors increases. On the other hand throughput decreases with increase sensing range and back-off time when transmission range increases

On a Modified Backoff Algorithm for MAC Protocol in MANETs

International Journal of Business Data Communications and Networking, 2000

In wireless communication environments, backoff is traditionally based on the IEEE binary exponential backoff (BEB). Using BEB results in a high delay in message transmission, collisions, and ultimately wasting the limited available bandwidth. As each node has to obtain medium access before transmitting a message, in dense networks, the collision probability in the medium access control (MAC) layer becomes very high, when a poor backoff algorithm is used. The logarithmic algorithm proposes some improvements to the backoff 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 backoff value. The BEB is used by the local area networks (LANs) standards, IEEE 802.11, MAC. BEB uses a uniform random distribution to choose the backoff value; this often leads to reducing the effect of a window-sized increment. This paper carries out a deeper study and analysis of the logarithmic backoff algorithm that uses logarithmic increments, instead of an exponential extension of the window size to eliminate the degrading effect of random number distribution. Results from simulation experiments reveal that the algorithm subject under study achieves higher throughput and less packet loss, when in a mobile ad hoc environment.

Improving Performance of 802.11 MAC by Optimizing DCF in Mobile ad-hoc Network

2012

Mobile Ad-hoc Network is a self configuring infrastructure-less network of mobile devices connected by wireless They have undergone rapid growth in the past several years because of their application in military and rescue service, disaster recovery operations, mobile conferencing and many other applications. The Media Access Control (MAC) data communication protocol sub-layer provides addressing and channel access control mechanisms that make it possible for network nodes to access common wireless channel through distributed coordination function (DCF). In the proposed work we will include analysis and implementation of conventional DCF protocol and proposes a new enhanced DCF protocol (EDCF) by improvements in the Binary Exponential Back-off Algorithm (BEB) and compare the performance of Enhanced DCF with conventional DCF protocol on different parameters. Keywords—Mobile Ad-hoc Network, Wireless Network, 802.11 MAC, Distributed Coordinated Function (DCF), Point Coordination Functi...

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.