This paper presents a novel carrier frequency offset estimation (CFO) algorithm for orthogonal frequency division multiplexing (OFDM)-based Wireless Local Area Networks (WLANs). Compared with previous approaches, this...This paper presents a novel carrier frequency offset estimation (CFO) algorithm for orthogonal frequency division multiplexing (OFDM)-based Wireless Local Area Networks (WLANs). Compared with previous approaches, this paper extends the whole frequency offset acquisition range by embedding a synthetic algorithm according to the preamble structure of WLANs symbols. The numerical results presented support the effectiveness of this algorithm by which the estimation error of the whole carrier frequency offset in the WLANs is effectively decreased.展开更多
In WLANs, stations sharing a common wireless channel are governed by IEEE 802.11 protocol. Many conscious studies have been conducted to utilize this precious medium efficiently. However, most of these studies have be...In WLANs, stations sharing a common wireless channel are governed by IEEE 802.11 protocol. Many conscious studies have been conducted to utilize this precious medium efficiently. However, most of these studies have been done either under assumption of idealistic channel condition or with unlimited retransmitting number. This paper is devoted to investigate influence of limited retransmissions and error level in the utilizing channel on the network throughput, probability of packet dropping and time to drop a packet. The results show that for networks using basic access mechanism the throughput is suppressed with increasing amount of errors in the transmitting channel over all the range of the retry limit. It is also quite sensitive to the size of the network. On the other side, the networks using four-way handshaking mechanism has a good immunity against the error over the available range of retry limits. Also the throughput is unchangeable with size of the network over the range of retransmission limits. However, the throughput does not change with retry limits when it exceeds the maximum number of the backoff stage in both DCF’s mechanisms. In both mechanisms the probability of dropping a packet is a decreasing function with number of retransmissions and the time to drop a packet in the queue of a station is a strong function to the number of retry limit, size of the network, the utilizing medium access mechanism and amount of errors in the channel.展开更多
With its rapid development in the wireless markets, IEEE 802.11 WLAN is experiencing a huge popularity. However, due to the limitation of frequency bandwidth of WLANs, it is essential that the available radio resource...With its rapid development in the wireless markets, IEEE 802.11 WLAN is experiencing a huge popularity. However, due to the limitation of frequency bandwidth of WLANs, it is essential that the available radio resource should be fully utilized to offer different services to multiple users. In order to maximize system throughput while still guaranteeing the fairness among users, a proportional fairness based algorithm is proposed in this work. Since most of the previous resource allocation algorithms were simply based on the channel conditions without taking into account user's demand, in this paper, we introduce the theory of fuzzy synthetic evaluation(FSE) which also allows us to consider user's demand as an important factor. As such, the fairness among users can be improved based on different users' requirements for services. In addition, a channel state information based rate adaptation scheme is also proposed. Through simulation studies, the results clearly validate that our proposed scheme shows advantages on providing user fairness while still improving the system throughput.展开更多
随着WLAN技术快速迭代,传统测试模式在需求分析、用例设计等环节暴露出人工依赖性高、效率低等痛点。大语言模型(large language model,L LM)为测试革新提供了路径,本文提出全智能化测试方案,构建基础层、平台层、应用层技术架构,明确...随着WLAN技术快速迭代,传统测试模式在需求分析、用例设计等环节暴露出人工依赖性高、效率低等痛点。大语言模型(large language model,L LM)为测试革新提供了路径,本文提出全智能化测试方案,构建基础层、平台层、应用层技术架构,明确历史经验和最佳实践提示词工程化、知识分层向量化、数据和关键交付件FewShot化等关键技术路径及分阶段实施策略。实践显示,该方案在用例生成、脚本生成等场景取得突破,能显著提升测试效率与质量,未来将助力下一代WLAN测试方法的突破。展开更多
针对笔记本电脑终端天线,提出了一种适用笔记本电脑无线局域网(Wireless Local Area Network,WLAN)的2.4 GHz、5 GHz、WiFi-6E的高隔离度多输入多输出(Multiple-input Multiple-output,MIMO)天线。为提高MIMO单元天线的端口隔离度,将一...针对笔记本电脑终端天线,提出了一种适用笔记本电脑无线局域网(Wireless Local Area Network,WLAN)的2.4 GHz、5 GHz、WiFi-6E的高隔离度多输入多输出(Multiple-input Multiple-output,MIMO)天线。为提高MIMO单元天线的端口隔离度,将一天线隔离枝节设置于笔记本电脑D壳溅镀层上,并且该天线的溅镀隔离枝节设置于MIMO单元天线之间。通过仿真和实测结果表明,该笔记本电脑WLAN天线在2412~2484 MHz、5150~5850 MHz和5925~7125 MHz内回波损耗均在-6 dB以下,天线效率≥-4.5 dB,隔离度<-20 dB。此外,该天线的溅镀隔离枝节结构简单,加工成本低,能广泛应用于笔记本电脑产品设计。展开更多
基于医院多业务接入复杂性与内外网协同需求,研究无线局域网(Wireless Local Area Network,WLAN)系统的拓扑架构、接入控制、调度机制及资源优化方法。阐述面向角色的动态接入控制策略,介绍覆盖建模与容量规划方法,并在仿真平台上构建...基于医院多业务接入复杂性与内外网协同需求,研究无线局域网(Wireless Local Area Network,WLAN)系统的拓扑架构、接入控制、调度机制及资源优化方法。阐述面向角色的动态接入控制策略,介绍覆盖建模与容量规划方法,并在仿真平台上构建典型场景,开展协同机制与传统机制的性能对比分析。分析结果表明,所提方案在吞吐量、时延控制、信道利用效率方面具有显著优势,具备良好的工程适用性与系统可扩展性。展开更多
Mobile data traffic is going through an explosive growth recently as mobile smart devices become more and more ubiquitous, causing huge pressure on cellular network. Taking advantage of its low cost and easy-to-deploy...Mobile data traffic is going through an explosive growth recently as mobile smart devices become more and more ubiquitous, causing huge pressure on cellular network. Taking advantage of its low cost and easy-to-deploy feature, wireless local-area networks（WLAN） becomes increasingly popular to offload data streams from cellular network, followed by higher and higher density of its deployment. However, the high density of WLAN will cause more interference, which results in degradation of its performance. Therefore, in order to enhance the performance of the network, we aim to minimize the interference caused by high density of WLAN. In this paper, we propose a novel power control scheme to achieve the above aim. We use the quality of experience（QoE） evaluation to coordinate the power of each access point（AP） and finally realize the optimization of the entire network. According to the simulation results, our scheme improves the performance of the network significantly in many aspects, including throughput and QoE.展开更多
针对采用分布式并行方法仿真WLAN(wireless local area network)场景时存在的随终端节点个数增加而效率降低的问题,提出了一种面向WLAN的分布式分层并行仿真方法。基于WLAN的星状网络拓扑结构,令仿真接入节点的进程为主进程,负责WLAN全...针对采用分布式并行方法仿真WLAN(wireless local area network)场景时存在的随终端节点个数增加而效率降低的问题,提出了一种面向WLAN的分布式分层并行仿真方法。基于WLAN的星状网络拓扑结构,令仿真接入节点的进程为主进程,负责WLAN全网中其他仿真节点的时间同步;将所有仿真终端节点的进程均匀分为若干组,由组长负责该组内进程的同步。在主进程广播仿真开始事件后,组长进程先收集本组组员终端节点推进结束消息,当收齐后再向主进程汇报。形成“主进程-组长进程-组员进程”的3层分层结构。在不同计算负荷下,仿真分析并得到了分层仿真方法的时间增益因子闭合表达式。仿真结果表明,与现有不分层的仿真方法相比,当平均计算负荷为1.2倍单位时长、节点个数为100时,所提分层仿真方法的增益可达50%。展开更多
随着智能电网系统中移动终端的增加,其对传输数据低时延、大带宽和高可靠性的需求尤为紧迫。为解决其中无线传输、信息处理和可靠性不足等问题,文章采用“切片分组网(sliced packet network,SPN)+可信无线局域网(wireless local area ne...随着智能电网系统中移动终端的增加,其对传输数据低时延、大带宽和高可靠性的需求尤为紧迫。为解决其中无线传输、信息处理和可靠性不足等问题,文章采用“切片分组网(sliced packet network,SPN)+可信无线局域网(wireless local area network,WLAN)”通信新技术网络架构,建立多种移动终端设备安全无线传输和计算任务卸载的总时延优化卸载模型,提出一种基于交替优化技术的算法。仿真结果表明,该策略不仅保证设备安全高效地接入网络,还可显著降低传输时延,具有优异的成本效益。展开更多
目前,地铁上使用的自动控制系统是车地无线通信系统,比较成熟的车地无线通信系统有两种方式,即无线局域网(WLAN)和长期演进(Long Term Evolution,LTE)。WLAN系统不适合为高速移动提供技术支持,存在频率干扰、信号不稳定、无法进行优先...目前,地铁上使用的自动控制系统是车地无线通信系统,比较成熟的车地无线通信系统有两种方式,即无线局域网(WLAN)和长期演进(Long Term Evolution,LTE)。WLAN系统不适合为高速移动提供技术支持,存在频率干扰、信号不稳定、无法进行优先调度、不胜任综合承载的缺点;而LTE技术适合高速移动的环境,具有信号覆盖广且均匀、抗干扰能力强等优点。本文以城市地铁中的具体案例为切入点,探讨WLAN技术的车地通信系统,分析LTE技术的车地无线传输技术,提出车地通信系统中信号传输中断的解决方案,以供参考。展开更多
The World WLAN Application Alliance(WAA),a non-profit independent organization,and Informa Tech held the roundtable meeting themed creating a secure and sustainable home Wi-Fi network on February 28 in Barcelona,Spain...The World WLAN Application Alliance(WAA),a non-profit independent organization,and Informa Tech held the roundtable meeting themed creating a secure and sustainable home Wi-Fi network on February 28 in Barcelona,Spain.Sponsored by Huawei Technologies Co..展开更多
We are all witnesses to the widespread use of wireless LANs (WLAN) and their easy implementation in indoor environments. Wi-Fi is the most popular technology for the WLAN. However, interference caused by building mate...We are all witnesses to the widespread use of wireless LANs (WLAN) and their easy implementation in indoor environments. Wi-Fi is the most popular technology for the WLAN. However, interference caused by building materials is a common, yet often overlooked, contributor to poor Wi-Fi performance. This interference occurs due to the nature of radio wave propagation and the characteristics of the wireless communication system. Therefore, during the implementation of these networks, one must consider the quasi-static nature of the Wi-Fi signal and its dependence on the influence of various building materials on the propagation of these waves. This paper presents the effects of building materials and structures on indoor environments for Wi-Fi 2.4 GHz and 5 GHz. To establish the interdependencies between factors influencing electric field levels, measurements were conducted in an experimental Wi-Fi network at different distances from the access point (AP). The results obtained show that the electric field strength of the Wi-Fi signal decreases depending on the distance, the building materials, and the transmitted frequency. Concrete material had the most significant impact on the strength of the electric field in Wi-Fi, while glass had a relatively minor effect on reducing it. Wi-Fi operates within the radio frequency spectrum, typically utilizing frequencies in the 2.4 GHz and 5 GHz bands. Additionally, measurements revealed that Wi-Fi signal penetration is more pronounced at lower frequencies (2.4 GHz) as opposed to the Wi-Fi signal 5 GHz. The findings can be used to address the impact of building materials and structures on indoor radio wave propagation, ultimately ensuring seamless Wi-Fi signal coverage within buildings.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 2004012F33AA), and Education Foundation of Zhe- jiang Education Department (No. 20040125-66), China
文摘This paper presents a novel carrier frequency offset estimation (CFO) algorithm for orthogonal frequency division multiplexing (OFDM)-based Wireless Local Area Networks (WLANs). Compared with previous approaches, this paper extends the whole frequency offset acquisition range by embedding a synthetic algorithm according to the preamble structure of WLANs symbols. The numerical results presented support the effectiveness of this algorithm by which the estimation error of the whole carrier frequency offset in the WLANs is effectively decreased.
文摘In WLANs, stations sharing a common wireless channel are governed by IEEE 802.11 protocol. Many conscious studies have been conducted to utilize this precious medium efficiently. However, most of these studies have been done either under assumption of idealistic channel condition or with unlimited retransmitting number. This paper is devoted to investigate influence of limited retransmissions and error level in the utilizing channel on the network throughput, probability of packet dropping and time to drop a packet. The results show that for networks using basic access mechanism the throughput is suppressed with increasing amount of errors in the transmitting channel over all the range of the retry limit. It is also quite sensitive to the size of the network. On the other side, the networks using four-way handshaking mechanism has a good immunity against the error over the available range of retry limits. Also the throughput is unchangeable with size of the network over the range of retransmission limits. However, the throughput does not change with retry limits when it exceeds the maximum number of the backoff stage in both DCF’s mechanisms. In both mechanisms the probability of dropping a packet is a decreasing function with number of retransmissions and the time to drop a packet in the queue of a station is a strong function to the number of retry limit, size of the network, the utilizing medium access mechanism and amount of errors in the channel.
基金partially supported by the Academy of Finland (Decision No. 284748, 288473)
文摘With its rapid development in the wireless markets, IEEE 802.11 WLAN is experiencing a huge popularity. However, due to the limitation of frequency bandwidth of WLANs, it is essential that the available radio resource should be fully utilized to offer different services to multiple users. In order to maximize system throughput while still guaranteeing the fairness among users, a proportional fairness based algorithm is proposed in this work. Since most of the previous resource allocation algorithms were simply based on the channel conditions without taking into account user's demand, in this paper, we introduce the theory of fuzzy synthetic evaluation(FSE) which also allows us to consider user's demand as an important factor. As such, the fairness among users can be improved based on different users' requirements for services. In addition, a channel state information based rate adaptation scheme is also proposed. Through simulation studies, the results clearly validate that our proposed scheme shows advantages on providing user fairness while still improving the system throughput.
文摘随着WLAN技术快速迭代,传统测试模式在需求分析、用例设计等环节暴露出人工依赖性高、效率低等痛点。大语言模型(large language model,L LM)为测试革新提供了路径,本文提出全智能化测试方案,构建基础层、平台层、应用层技术架构,明确历史经验和最佳实践提示词工程化、知识分层向量化、数据和关键交付件FewShot化等关键技术路径及分阶段实施策略。实践显示,该方案在用例生成、脚本生成等场景取得突破,能显著提升测试效率与质量,未来将助力下一代WLAN测试方法的突破。
文摘基于医院多业务接入复杂性与内外网协同需求,研究无线局域网(Wireless Local Area Network,WLAN)系统的拓扑架构、接入控制、调度机制及资源优化方法。阐述面向角色的动态接入控制策略,介绍覆盖建模与容量规划方法,并在仿真平台上构建典型场景,开展协同机制与传统机制的性能对比分析。分析结果表明,所提方案在吞吐量、时延控制、信道利用效率方面具有显著优势,具备良好的工程适用性与系统可扩展性。
基金supported by the WLAN Achievement Transformation based on SDN of Beijing Municipal Commission of Education (201501001)
文摘Mobile data traffic is going through an explosive growth recently as mobile smart devices become more and more ubiquitous, causing huge pressure on cellular network. Taking advantage of its low cost and easy-to-deploy feature, wireless local-area networks（WLAN） becomes increasingly popular to offload data streams from cellular network, followed by higher and higher density of its deployment. However, the high density of WLAN will cause more interference, which results in degradation of its performance. Therefore, in order to enhance the performance of the network, we aim to minimize the interference caused by high density of WLAN. In this paper, we propose a novel power control scheme to achieve the above aim. We use the quality of experience（QoE） evaluation to coordinate the power of each access point（AP） and finally realize the optimization of the entire network. According to the simulation results, our scheme improves the performance of the network significantly in many aspects, including throughput and QoE.
文摘针对采用分布式并行方法仿真WLAN(wireless local area network)场景时存在的随终端节点个数增加而效率降低的问题,提出了一种面向WLAN的分布式分层并行仿真方法。基于WLAN的星状网络拓扑结构,令仿真接入节点的进程为主进程,负责WLAN全网中其他仿真节点的时间同步;将所有仿真终端节点的进程均匀分为若干组,由组长负责该组内进程的同步。在主进程广播仿真开始事件后,组长进程先收集本组组员终端节点推进结束消息,当收齐后再向主进程汇报。形成“主进程-组长进程-组员进程”的3层分层结构。在不同计算负荷下,仿真分析并得到了分层仿真方法的时间增益因子闭合表达式。仿真结果表明,与现有不分层的仿真方法相比,当平均计算负荷为1.2倍单位时长、节点个数为100时,所提分层仿真方法的增益可达50%。
文摘随着智能电网系统中移动终端的增加,其对传输数据低时延、大带宽和高可靠性的需求尤为紧迫。为解决其中无线传输、信息处理和可靠性不足等问题,文章采用“切片分组网(sliced packet network,SPN)+可信无线局域网(wireless local area network,WLAN)”通信新技术网络架构,建立多种移动终端设备安全无线传输和计算任务卸载的总时延优化卸载模型,提出一种基于交替优化技术的算法。仿真结果表明,该策略不仅保证设备安全高效地接入网络,还可显著降低传输时延,具有优异的成本效益。
文摘目前,地铁上使用的自动控制系统是车地无线通信系统,比较成熟的车地无线通信系统有两种方式,即无线局域网(WLAN)和长期演进(Long Term Evolution,LTE)。WLAN系统不适合为高速移动提供技术支持,存在频率干扰、信号不稳定、无法进行优先调度、不胜任综合承载的缺点;而LTE技术适合高速移动的环境,具有信号覆盖广且均匀、抗干扰能力强等优点。本文以城市地铁中的具体案例为切入点,探讨WLAN技术的车地通信系统,分析LTE技术的车地无线传输技术,提出车地通信系统中信号传输中断的解决方案,以供参考。
文摘The World WLAN Application Alliance(WAA),a non-profit independent organization,and Informa Tech held the roundtable meeting themed creating a secure and sustainable home Wi-Fi network on February 28 in Barcelona,Spain.Sponsored by Huawei Technologies Co..
文摘We are all witnesses to the widespread use of wireless LANs (WLAN) and their easy implementation in indoor environments. Wi-Fi is the most popular technology for the WLAN. However, interference caused by building materials is a common, yet often overlooked, contributor to poor Wi-Fi performance. This interference occurs due to the nature of radio wave propagation and the characteristics of the wireless communication system. Therefore, during the implementation of these networks, one must consider the quasi-static nature of the Wi-Fi signal and its dependence on the influence of various building materials on the propagation of these waves. This paper presents the effects of building materials and structures on indoor environments for Wi-Fi 2.4 GHz and 5 GHz. To establish the interdependencies between factors influencing electric field levels, measurements were conducted in an experimental Wi-Fi network at different distances from the access point (AP). The results obtained show that the electric field strength of the Wi-Fi signal decreases depending on the distance, the building materials, and the transmitted frequency. Concrete material had the most significant impact on the strength of the electric field in Wi-Fi, while glass had a relatively minor effect on reducing it. Wi-Fi operates within the radio frequency spectrum, typically utilizing frequencies in the 2.4 GHz and 5 GHz bands. Additionally, measurements revealed that Wi-Fi signal penetration is more pronounced at lower frequencies (2.4 GHz) as opposed to the Wi-Fi signal 5 GHz. The findings can be used to address the impact of building materials and structures on indoor radio wave propagation, ultimately ensuring seamless Wi-Fi signal coverage within buildings.
