Analytic performance of IEEE 802.11 distributed coordination function that takes into account hidden node problem and unsaturated traffic condition is presented for symmetric networks. This enables us to estimate the performance of practical wireless local area networks more accurately. It is shown that the presence of hidden nodes barely affects the network performance in low traffic conditions, but it causes 33% performance loss in moderate traffic scenarios. Analytical results presented in the paper are backed by simulation results.
"In , the author introduces a two-dimensional Markov chain to represent backoff behavior, and derives the throughput in the saturated situation. In  , the authors extend  so as to consider the influence of hidden nodes. These work can describe accurate behavior of 802.11 "
"Later on,  proposed an accurate unsaturated system analysis. The throughput analysis is shown in  by taking into account a Hidden Node (HN) scenario, which is an important problem inherent to the basic access scheme of DCF. With the ever increasing popularity of IEEE 802.11 standard based WLAN, it is highly probable that a station (STA) is in the coverage area of overlapping Basic Service Set (OBSS), which may result in a HN problem. "
[Show abstract][Hide abstract] ABSTRACT: Recently, the IEEE 802.11 standard based Wireless Local Area Networks (WLAN) have become more popular and are widely deployed. It is anticipated that WLAN will play an important rule in the future wireless communication systems in order to provide several gigabits data rate. IEEE 802.11ac is one of the ongoing WLAN standard aiming to support very high throughput (VHT) with data rate of up to 6 Gbps below the 6 GHz band. In the development of IEEE 802.11ac standard, several new physical layer (PHY) and medium access control layer (MAC) features are taken into consideration, such as employing wider bandwidth in PHY and incrementing the limits of frame aggregation in MAC. However, due to the newly introduced features, some traditional techniques used in previous standards could face some problems. This paper presents a performance analysis of 802.11ac Distributed Coordination Function (DCF) in presence of hidden nodes in overlapping BSS (OBSS) environment. The effectiveness of DCF in IEEE 802.11ac WLAN when using different primary channels and different frequency bandwidth has also been discussed. Our results indicate that the traditional RTS/CTS handshake mechanism faces shortcomings and needs to be modified in order to support the newly defined 802.11ac amendment.
"Based on this assumption, if (1 À a) represents the probability that a contending station will not transmit in a randomly chosen slot time, then according to Refs.   the probability that a hidden station will not transmit during the vulnerable period of y successive slots equals (1 À a) y . However, this assumption violates the characteristics of the Markov chain which requires that the transmission probability in each backoff slot only depends on what happened in the previous slot. "
[Show abstract][Hide abstract] ABSTRACT: In this paper, we present an analytical model to evaluate the hidden station effect on the performance of the IEEE 802.11 Distributed Coordination Function (DCF) in both non-saturation and saturation condition. DCF is a random channel-access scheme based on Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) method and the exponential backoff procedure. DCF is widely used and can support both wireless network with an access point and ad hoc wireless network because of its random channel-access method. On the other hand, this method unavoidably suffers the hidden station effect that causes significant performance degradation. As shown in this paper, hidden stations occur frequently in real-world settings, and the performance impact on the 802.11 DCF is a significant concern, but it has not been adequately studied. We study this problem through a spatial–temporal analysis and a Markov chain model. Our model generalizes the existing work on the performance modeling of 802.11 DCF for both non-saturation and saturation conditions. The scenario of no hidden station can be considered as a special case in our model. The performance of our model is evaluated by comparison with ns-2 simulations.
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