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Since the IEEE 802.11 DCF adopted the Binary Exponential Back-off (BEB) algorithm in its contention window adjustment scheme, many alternative back-off algorithms were proposed in order to enhance the performance. Among them is an Exponential Increase Exponential Decrease (EIED) back-off algorithm, whose performance was simulated and analyzed in a special case of doubling or halving the contention...
The Distributed Coordination Function (DCF) of IEEE 802.11 is one of most commonly used MAC protocol in channel-shared wireless network, but it can't support differentiated services among various applications. In this paper, a novel probability back-off MAC protocol is proposed to provide service differentiation as well as enhance the overall system throughput. We analyze our scheme by using a Markov...
In this paper the throughput, frame discard probability, and average frame delay performance of DCF in IEEE 802.11 are analyzed and evaluated for different parameters, such as the number of users and frame size considering the network delay and the CTS/ACK time out. Related analysis and statements will be helpful to research and development of wireless networks and products.
This paper provides a simple and accurate analysis using Markov chain modeling to compute IEEE 802.11 DCF performance, in the presence of channel errors. We extend the analytical model of IEEE 802.11 DCF from Bianchi model to study throughput performance under noisy situation, where the node's transmit queue may be at times empty and then extension of his model to a nonsaturated environment and also...
In this paper, on the base of comprehensive consideration of game theory and the IEEE 802.11 DCF Distributed Coordination Function, for the characteristics of the wireless sensor network, we make the channel competitive process between nodes molded into incompletely information dynamic game. Then improve DCF by the Nash equilibrium game strategy. The simulation results show that the proposed model...
In this paper, we provide an extended model for analytical analysis of an IEEE 802.11 Wireless Local Area Networks (WLANs) that accommodates the nonsaturated operation of the network, homogeneous traffic and the noisy wireless channel. We propose a modified Distributed Coordination Function (DCF) and model it with a discrete time Markov chain, with the aim of improving the throughput when stations...
IEEE 802.11 protocol is widely used in Wireless Local Area Networks (WLAN) for its high data transmission rates. The formation flying satellite system has a short inter-satellite distance, which is similar to WLAN. It may be a good choice to apply IEEE 802.11 protocol in inter-satellite communication to increase throughput. However inter-satellite distance is longer than what desired by WLAN, so IEEE...
A MAC mechanism of supporting integrated voice and data service in ad hoc networks is presented. The state transition diagram of the proposed mechanism is described, and then throughput and packet time delay performances are analyzed by using Markov model. Moreover, performances comparison between the proposed mechanism and 802.11 DCF are made. Numerical results show that the proposed MAC mechanism...
The distributed coordination function is one of three channel access control protocols specified by the IEEE 802.11 standard. In this paper we present a method of measuring DCF performance using a test bed built with off-the-shelf hardware. Performance is measured by normalized aggregate throughput as a function of the number of stations contending for channel access. We present measurements for both...
Distributed coordination function (DCF) is the main technique of IEEE 802.11, which relies on carrier sense multiple access/collision avoidance (CSMA/CA) to reduce collision among stations. In this paper, a scheme is proposed to improve the throughput performance of the DCF in a hybrid environment, where a ready to send (RTS) frame is used when the length of a packet exceeds a threshold. Suppose,...
This paper presents a novel mathematical model for evaluating the performance of infrastructure wireless local area networks (WLANs) carrying voice and data traffic flows. We evaluate the performance of the access point (AP) flows and of the stations that employ IEEE 802.11 Distributed Coordination Function (DCF) as contention mechanism to access the channel. Metrics as throughput, average delay,...
Extensive research addressing IEEE 802.11 distributed coordination function (DCF) and 802.11e enhanced distributed channel access (EDCA) performance analysis, by means of analytical models, exists in the literature. It started mainly with the famous Bianchi's model and still continues today as several aspects have not been yet covered. Indeed, the ultimate goal is to obtain the model that provides...
Wireless LANs have achieved a tremendous amount of growth in recent years. During this time, user requirements have evolved, so it is necessary to have differentiation mechanisms in the access networks to achieve user requirements. WLAN standard IEEE 802.11 doesn't provide any differentiation between different services to achieve throughput and delay requirement, this paper propose a new modification...
IEEE 802.11 DCF exhibits poor performance as the number of nodes increases in a wireless LAN due to high collision probability on each transmission. In this paper, based on the optimal constant backoff (OCB) window scheme which fixes the backoff window at every backoff stage, a virtual collision solution (VCS) scheme is proposed to reduce the collision probability and to enhance the throughput performance...
This paper investigates the relative performance of unicast and broadcast traffic traversing a one-hop ad hoc network utilising the 802.11 DCF. An extended Markov model has been developed and validated through computer simulation, which successfully predicts the respective performance of unicast and broadcast in a variety of mixed traffic scenarios. Under heavy network traffic conditions, a significant...
This paper presents an analytical model for the performance study of IEEE 802.11 distributed coordination function (DCF). The maximum throughput can be achieved well below the saturated load. The analytical model for finite load must be studied to know the performance of the medium access control (MAC) layer below the saturated load. We extend the Bianchipsilas saturation model for the nonsaturated...
The neighbor turn taking (NTT) Medium Access Control (MAC) protocol is a loosely scheduled MAC, whose intended purpose is for use in wireless ad hoc networking environments where the node mobility is low. This protocol has been previously shown via simulation to perform better than IEEE 802.11 in terms of end-to-end packet latency and rate of successfully transmitted packets under saturated conditions...
A mechanism named virtual collision mechanism (VCM) was proposed to improve IEEE 802.11 distributed coordination function's (DCF) performance, in which a super slot includes two slots. This paper extends the 2-slot VCM into multi-slot VCM and proposes the multi-slot VCM's model, in which a super slot includes several slots. Plenty of simulations and analysis are carried out to evaluate the multi-slot...
Based on the protocol of IEEE 802.11 for ad hoc networks, the distributed coordination function (DCF) of ad hoc networks was modified, and an adaptive minimum contention window binary exponential backoff algorithm (AWBEB algorithm) was presented. We use a 2D Markov chain model to educe the stationary distribution probabilities and the probability that a given node will transmit in an arbitrary time...
The limited number of orthogonal channels and autonomous installations of hot spots and home wireless networks often leave neighboring 802.11 basic service sets (BSSs) operating on the same or overlapping channels, therefore interfering with each other. However, the 802.11 medium access control (MAC) does not work well in resolving inter-BSS interference due to the well-known hidden/exposed-receiver...
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