共查询到20条相似文献,搜索用时 11 毫秒
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《AEUE-International Journal of Electronics and Communications》2008,62(5):327-337
Since its release in 1999, IEEE 802.11 became the defacto standard for Wireless Local Area Networks (WLANs). Despite its widespread deployment, analytical modeling efforts of the IEEE 802.11 standard have been focusing on the performance under saturated load conditions. This paper aims at analytically modeling and analyzing the performance of the IEEE 802.11-based networks. The model proposed in this paper follows exactly the real implementation of the DCF method. Extensive NS2 simulations are conducted to verify the results of the analytical model. Our model gives a new interpretation for the saturation behavior reported in the literature, relates the critical point (inflection point) to the various system and traffic parameters and analytically explains why the RTS/CTS mechanism is favorable for certain offered loads. 相似文献
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Xiaomin Ma Xianbo Chen 《Communications Letters, IEEE》2007,11(8):686-688
In this letter, saturation performance of broadcast service in IEEE 802.11 is studied analytically and by simulation. Having investigated the features of the broadcast service, we point out that the analytic models for saturation performance evaluation of IEEE 802.11 unicast communication cannot be simply reduced for analysis of broadcast service. Under realistic assumptions, we construct an analytic model to characterize operation of the backoff counter for broadcast, thus obtain closed form solutions to the saturation throughput and packet delivery ratio. Simulation validates the proposed model. Numerical results reveal characteristics of the broadcast service. 相似文献
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IEEE802.11e和IEEE802.15.3两个协议在当今无线网络中应用的十分广泛,在详细描述了两者的信道接入机制的基础上,对协议性能进行了分析对比,并指出了各自适用的范围. 相似文献
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Wireless Networks - In the majority of IEEE 802.11 series wireless networks, the quality of service (QoS) requirements are related to the queueing behavior of buffers in mobile stations, e.g., the... 相似文献
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The IEEE has standardized the 802.11 protocol for wireless local area networks. The primary medium access control (MAC) technique of 802.11 is called the distributed coordination function (DCF). The DCF is a carrier sense multiple access with collision avoidance (CSMA/CA) scheme with binary slotted exponential backoff. This paper provides a simple, but nevertheless extremely accurate, analytical model to compute the 802.11 DCF throughput, in the assumption of finite number of terminals and ideal channel conditions. The proposed analysis applies to both the packet transmission schemes employed by DCF, namely, the basic access and the RTS/CTS access mechanisms. In addition, it also applies to a combination of the two schemes, in which packets longer than a given threshold are transmitted according to the RTS/CTS mechanism. By means of the proposed model, we provide an extensive throughput performance evaluation of both access mechanisms of the 802.11 protocol 相似文献
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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. 相似文献
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IEEE 802.11n MAC Enhancement and Performance Evaluation 总被引:1,自引:0,他引:1
The IEEE 802.11-based WiFi wireless technology is one of the most promising technologies to provide ubiquitous networking
access. The IEEE 802.11 working group has always strived to improve this wireless technology through creating new amendments
to the base 802.11 standard. Recently, IEEE 802.11n amendment was created to enhance 802.11 for higher throughput operation.
Not only new Physical Layer enhancements are standardized, but new Medium Access Control Layer mechanism are also defined.
In this paper, we examine the network performance enhancement by the proposed 802.11n MAC layer features: aggregation, block
acknowledgement, and reverse direction mechanism. We implemented a new 802.11n module in the NS-2 simulation platform. The
simulation results demonstrated the effectiveness of 802.11n MAC layer enhancement. VoIP performance is effectively improved
with 802.11n MAC enhancement. 相似文献
9.
Soo Young Shin 《AEUE-International Journal of Electronics and Communications》2013,67(8):686-689
This paper evaluates throughput of IEEE 802.15.4 network under the interference of a saturated IEEE 802.11 network using an analytic method. Packet losses due to both collisions among IEEE 802.15.4 and mutual interference between IEEE 802.15.4 and 802.11 are considered for throughput analysis. To include the interference from IEEE 802.11, we modified the state transition probabilities of IEEE 802.15.4 two-state Markov process model. Simulation results closely match the theoretical expressions confirming the effectiveness of the proposed model. 相似文献
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Zhen-ning Kong Tsang D.H.K. Bensaou B. Deyun Gao 《Selected Areas in Communications, IEEE Journal on》2004,22(10):2095-2106
The new standard IEEE 802.11e is specified to support quality-of-service in wireless local area networks. A comprehensive study of the performance of enhanced distributed channel access (EDCA), the fundamental medium access control mechanism in IEEE 802.11e, is reported in this paper. We present our development of an analytical model, in which most new features of the EDCA such as virtual collision, different arbitration interframe space (AIFS), and different contention window are taken into account. Based on the model, we analyze the throughput performance of differentiated service traffic and propose a recursive method capable of calculating the mean access delay. Service differentiation functionality and effectiveness of the EDCA are investigated through extensive numerical and simulation results. The model and the analysis provide an in-depth understanding and insights into the protocol and the effects of different parameters on the performance. 相似文献
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Performance Analysis of IEEE 802.11 DCF in Imperfect Channels 总被引:1,自引:0,他引:1
《Vehicular Technology, IEEE Transactions on》2006,55(5):1648-1656
IEEE 802.11 is the most important standard for wireless local area networks (WLANs). In IEEE 802.11, the fundamental medium access control (MAC) scheme is the distributed coordination function (DCF). To understand the performance of WLANs, it is important to analyze IEEE 802.11 DCF. Recently, several analytical models have been proposed to evaluate the performance of DCF under different incoming traffic conditions. However, to the best of the authors' knowledge, there is no accurate model that takes into account both the incoming traffic loads and the effect of imperfect wireless channels, in which unsuccessful packet delivery may occur due to bit transmission errors. In this paper, the authors address this issue and provide an analytical model to evaluate the performance of DCF in imperfect wireless channels. The authors consider the impact of different factors together, including the binary exponential backoff mechanism in DCF, various incoming traffic loads, distribution of incoming packet size, queueing system at the MAC layer, and the imperfect wireless channels, which has never been done before. Extensive simulation and analysis results show that the proposed analytical model can accurately predict the delay and throughput performance of IEEE 802.11 DCF under different channel and traffic conditions. 相似文献
13.
IEEE802.11系列标准是无线局域WLAN(Wireless Local Area Network)中应用最广的标准。其中IEEE802.11a工作在5.8GHz频段,除了不受向下兼容性的限制外,同频段系统之间的干扰也很小,因而比较适合高密度、高容量的网络。IEEE802.11a采用正交频分复用(OFDM)调制方式,理论最高传输速率可达54Mbit/s,但在实际应用中,其传输净数据率均远低于此。为了评估其数据业务支持能力,指导网络容量规划,文章主要从MAC层协议性能方面对IEEE802.11a WLAN网络的性能进行了分析,并给出了其实际吞吐量。 相似文献
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《AEUE-International Journal of Electronics and Communications》2014,68(7):667-675
The multi-rate transmission mechanism in IEEE 802.11 can improve its reliability and robustness. However, it causes a performance anomaly. After analyzing the reasons for the performance anomaly in multi-rate mechanism, we propose a new scheme to solve the performance anomaly. By adjusting packet size according to the transmission rate, this scheme guarantees that these nodes with different transmit rates can access wireless channel fairly. Theoretical analysis and performance evaluation show that the proposed scheme can well solve the performance anomaly problem. 相似文献
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Performance issues with IEEE 802.11 in ad hoc networking 总被引:1,自引:0,他引:1
Although 802.11 is initially designed for infrastructure-based networks, the distributed coordination function allows mobiles to access the radio medium without the need for a base station. Thus, studies in wireless multihop networks, also called ad hoc networks, often rely on the use of IEEE 802.11 for the physical and MAC layers. However, for a couple of years the use of 802.11 in ad hoc networks has been discussed. Different scenarios show serious performance issues. The performance offered by 802.11 is often low and directly impacts the performance of higher-layer protocols. In this article we provide a summary of the different performance issues extracted so far. We classify basic situations according to the main effects. We then present a quick survey of the possible solutions to these problems. This classification is intended to help design appropriate MAC protocols dedicated to ad hoc networks. 相似文献
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Integrating wireless LAN (WLAN) techniques with the third generation cellular networks has become a promising way to improve the performance of wireless systems. As WLANs play an important role in such heterogeneous systems, the performance of WLANs becomes important to the whole system. It is well known that WLANs provide a physical layer multi-rate capability, and hence MAC layer mechanisms are needed to exploit this capability. In this paper, we propose a novel MAC layer relay-enabled point coordination function (PCF) protocol, called rPCF, to exploit the physical layer multi-rate capability. Since WLAN supports multiple data rates in response to different channel conditions, data packets may be delivered faster through a relay node than through the direct link if the direct link has low quality and low rate. To enable MAC layer relay, the access point needs to collect information about the channel conditions, and notify the mobile nodes which data rate to use and whether to transmit the data through a relay station. We design protocols to achieve this goal and refine these protocols to minimize the control overhead. Simulation results show that rPCF can significantly improve the system performance in terms of system throughput and transmission delay by adding only a negligible control overhead. 相似文献
20.
Chi-Sheng Lin Che-Kang Sun Jia-Chin Lin Bo-Chiuan Chen 《Telecommunication Systems》2013,52(4):1731-1742
A time-domain (TD) channel estimation (CE) technique is proposed in this paper to enhance the CE performance of IEEE 802.11p standards in cases when the pilot density is insufficient to accurately estimate channel states in rich-scattering environments. This technique is based on a least squares (LS) algorithm and assisted from Zadoff-Chu (ZC) sequences arranged into the symbol prefix and training preambles. The channel conditions tested in this paper were comprehensively simulated in urban, suburb and express-way scenarios. 相似文献