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
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
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
无线局域网WLANs(Wireless Local Area Network)、通用分组无线服务GPRS(General Packet Radio Service)、通用移动通信系统UMTS(Universal Mobile Telecommunication System)网络都可以为移动用户提供数据服务,它们分别可以满足用户对...无线局域网WLANs(Wireless Local Area Network)、通用分组无线服务GPRS(General Packet Radio Service)、通用移动通信系统UMTS(Universal Mobile Telecommunication System)网络都可以为移动用户提供数据服务,它们分别可以满足用户对不同带宽和不同服务质量的要求.一种融合了这三者的网络架构,并且可以保证移动用户的服务在不同网络中的连贯性,应该成为移动通信系统新的发展方向.在文章最后,还对该网络中使用的移动终端应具有的性能进行了描述.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.
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。
文摘无线局域网WLANs(Wireless Local Area Network)、通用分组无线服务GPRS(General Packet Radio Service)、通用移动通信系统UMTS(Universal Mobile Telecommunication System)网络都可以为移动用户提供数据服务,它们分别可以满足用户对不同带宽和不同服务质量的要求.一种融合了这三者的网络架构,并且可以保证移动用户的服务在不同网络中的连贯性,应该成为移动通信系统新的发展方向.在文章最后,还对该网络中使用的移动终端应具有的性能进行了描述.
